Orthotic Vision Therapy - Clinical Medical Guidelines Bulletins (2023)

Number: 0489

Policy

Observations:

This guideline addresses orthoptic vision therapy, which is considered an active intervention (eg, a combination of eye exercises and vision training maneuvers). This policy does not apply to the use of passive orthoptic or pleoptic devices such as B. Occlusion (eye patch), which is considered medically necessary in the case of amblyopia, and prism adjustment, which is considered medically necessary prior to strabismus surgery. .

Orthoptic or pleoptic devices are considered durable medical devices.>

Some Aetna plans specifically exclude vision therapy (orthoptic training) benefits. Review benefit plan descriptions. Under these plans, fees for orthoptic and/or pleoptic training (eye exercises) and training aids or vision therapy for any diagnosis must be disallowed due to this contractual exclusion.

In addition, most Aetna benefit plans exclude benefits, treatment, educational testing or training related to learning disabilities or developmental delays. Review benefit plan descriptions.

medical necessity

For plans without such an exclusion, Aetna will consider up to 12 orthoptic vision therapy visits or sessions as medically necessary to treat convergence insufficiency.

Orthoptic vision therapy requests of more than 12 visits for this indication are subject to medical review. Members should transition to a convergence insufficiency home exercise program (eg, pencil push-ups).

experimental and investigative

Orthoptic vision therapy is considered experimental by Aetna and experimental for all other indications (eg, anisometropic amblyopia, concussion, intermittent exotropia, traumatic brain injury, and vertical heterophoria).

The use of visual information processing assessments is considered experimental by Aetna and their clinical value has not been established.

Online/digital therapeutic vision training software (eg, RevitalVision) is considered experimental and investigational by Aetna for the treatment of amblyopia and all other indications due to insufficient evidence in the peer-reviewed literature. peers.

The digital eye-tracking system (eg, the CureSight system) is considered experimental and experimental by Aetna for the treatment of amblyopia and all other indications, as its efficacy has not been validated in well-designed prospective clinical studies. .

Related Policies

1. CPB 0078 - Learning disabilities, dyslexia and vision
2. CPB 0250 - Occupational Therapy
3. CPB 0321 - Behavioral Vision Therapy and Vision Restoration Therapy
4. CPB 0469 - Transcranial Magnetic Stimulation and Cranial Electrical Stimulation

background

Vision therapy includes a variety of non-surgical methods to correct or improve specific vision problems. It is a term used by optometrists and is defined as "an attempt to develop or enhance visual skills and abilities, improve visual comfort, ease, and efficiency, and alter visual processing or interpretation of visual information." exercises in the office and at home, carried out over weeks or months. In addition to exercises, lenses ("training glasses"), prisms, filters, patches, electronic dartboards, or balance boards may be used" (AAPOS, 2020b, 2020c ) Other modalities used by vision therapy advocates include sensory activities , motor and perception.

Orthoptic vision therapy may include occlusion (patching) therapy, over-less glasses, and orthoptic exercises. These interventions are considered "passive" or "active" vision therapy methods. Passive vision therapy usually involves part-time alternating occlusion (patching) of one eye and is used in younger children with intermittent exotropia to prevent or reduce oppression. Myopic glasses prescription is another method of passive vision therapy that is also used for intermittent exotropia, a common form of strabismus. Active vision therapy involves a combination of eye exercises and vision training maneuvers that can be prescribed at home or performed in weekly or more frequent office meetings (Coats & Paysse, 2021). Active vision therapy has been used primarily in the treatment of strabismus and other disorders of binocular function and ocular motility. A variety of devices and techniques are used, including flashlights and mirrors, biofeedback, video games, image tracing, puzzle solving, etc. In some cases, electronic or computerized optical instruments are used to enhance treatment. These activities are aimed at stimulating the proper functioning of the visual system or building compensatory systems to alleviate deficiencies that have been used to correct vision problems. This guideline does not address the medical necessity of so-called "passive" vision therapy, that is, the treatment of vision problems with eye patches, miotics, prisms, red filters, or lenses.

According to the American Association for Pediatric Ophthalmology and Strabismus (AAPOS), optometrists classify vision therapy into three main categories: orthoptic vision therapy (which includes eye exercises to improve binocular function and are taught in the office and performed at home), behavioral/perceptual vision therapy (including eye exercises to improve visual processing and visual perception), and vision therapy to prevent or correct nearsightedness (nearsightedness). According to the AAPOS, orthoptic eye exercises, as prescribed by pediatric ophthalmologists, orthoptists, and optometrists, may be beneficial in the treatment of symptomatic convergence failure; However, behavioral therapy is considered scientifically unproven. Also, there is no evidence that vision therapy slows the progression or corrects myopia. Evidence does not support the use of eye exercises or visual behavioral/perceptual therapy to improve long-term academic performance in children with learning disabilities (AAPOS, 2020b, 2020c).

Ortho-optics and pleoptics are common forms of vision therapy. Orthoptics are exercises to improve the function of the eye muscles. Proponents believe these exercises are particularly useful for treating strabismus and other binocular vision abnormalities. Pleoptics are exercises to improve poor eyesight if there are no indications of organic eye diseases.

For convenience, the term vision therapy is synonymous with the term orthoptics, and the terms are used interchangeably. Both vision therapy and orthoptics are related to eye movement and eye focusing exercises. Vision therapy is performed by optometrists, while orthoptics is generally performed by certified orthoptists who practice under the supervision of ophthalmologists. A key difference between optometric vision therapy and ophthalmic orthoptics is that optometrists primarily perform vision therapy in the office, while orthoptists typically prescribe exercises to be performed at home.

Vision therapy has been prescribed to relieve a variety of visual symptoms, including diplopia (double vision), blurred vision, and "asthenopia." Asthenopia is a term used for ailments that result from visual disturbances, including headaches, eyestrain, and excessive eye rubbing. Active vision therapy has also been recommended as a treatment for learning disabilities and to improve sports performance, focusing on the development of specific visual skills in athletes.

There is a wide spectrum of vision therapy techniques and methods among practitioners who perform vision therapy, making it difficult to standardize and evaluate vision therapy practice. The National Eye Institute (NEI) of the National Institutes of Health (NIH) recognizes the need for clinical trials of non-invasive treatments (such as orthoptics and vision training) to determine the presence of improvement in ocular alignment. and visual function in patients with early vision impairment, such as amblyopia and stereoscopic vision impairment. The American Academy of Ophthalmology (AAO) accepts eye exercises and other non-surgical treatments, usually performed by an orthopedist (a professional eye specialist working under the supervision of an ophthalmologist).The main thing) as beneficial for people with problems of the eye muscles. However, the AAO believes that these treatments should not be confused with vision therapy.

The American Academy of Pediatrics (AAP), AAPOS, the American Association of Certified Orthopedics (AACO), and the AAO (2009; reaffirmed 2014) issued a joint policy statement on learning disabilities, dyslexia, and vision that states : “There is no evidence to support the view that subtle eye or vision problems cause learning problems. Furthermore, the evidence does not support the concept that vision therapy or polarized lenses or filters are directly or indirectly effective in treating learning disabilities. Therefore, the claim that vision therapy improves vision cannot be proven. Diagnostic and treatment approaches without scientific evidence of efficacy are not supported or recommended."

Expert opinions on the effectiveness of vision therapy are divided. The stated positions of the American Optometric Association (AOA) and the College of Optometry in Vision Development (COVD) are not consistent with those of the AAO, AAP, and other organizations of medical professionals (AOA, 2009).

From a review of the literature, several general conclusions about vision therapy can be drawn.

• Assessing the effectiveness of vision therapy has been extremely difficult due to the small number and generally low quality of clinical trials investigating the effectiveness of vision therapy.
• Assessing the effectiveness of vision therapy is complicated by the lack of standard treatment methods or protocols. Often, the studies do not adequately specify the patient selection criteria or the methods and duration of the treatments used.
• Most of the literature on the efficacy of vision therapy is based on expert opinions of optometrists and ophthalmologists and on non-systematic retrospective reviews of cases seen in a particular practice. Few studies on the efficacy of vision therapy have used comparison groups and, with the exception of vision therapy for convergence insufficiency, virtually no adequate randomized controlled clinical trials of vision therapy have been published. There is also little evidence for the long-term effectiveness and durability of these treatments.
• Almost all published studies have small sample sizes and most studies lack statistical analysis of the data.
• Many of the studies cited to support the efficacy of vision therapy are old. Studies published before the development and introduction of modern clinical research methods do not provide basic information about the criteria used to select study participants, adequate descriptions of the treatments administered, or descriptions of the criteria used to determine success or outcome. treatment failure.
• Reviews of the literature by advocates of vision therapy have been particularly uncritical of the evidence. These reviews often fail to describe important weaknesses in the studies used to support the effectiveness of vision therapy, such as: B. Selection bias and poorly reported results. Due to poor methodology and reporting of these older studies, no conclusions about efficacy could generally be drawn from them.
• Many vision therapy reviews cite abstracts, unpublished manuscripts, and doctoral theses. These papers have not been peer-reviewed, are generally not widely available, and often do not meet rigorous research standards, and the results are often equivocal and ambiguous.
• The authors of vision therapy studies failed to identify or point to important weaknesses in their study design and important limitations in the conclusions that could be drawn from their studies. Often these studies do not report patient selection criteria, prior treatment, volume, intensity, and duration of activities. Little attempt is made to control for confounding variables, such as types of prior treatment. In most studies, the research design does not include a control group.

Most controlled trials on the efficacy of vision therapy have not used random assignment, and the comparison groups used in non-randomized trials have not been carefully matched for factors influencing therapy outcome. These studies also often lack therapist-observer blinding, independent statistical design, and independent analysis and evaluation of effects. Some do not provide a statistical analysis of the data and many do not control for confounding variables. Control subjects in several studies received no dummy or placebo treatments. The studies also reported their results in terms of mean scores and did not provide subgroup or group analyzes to identify the characteristics of patients most likely to respond to vision therapy. Furthermore, many of the studies reported high dropout rates and these studies did not use intention-to-treat analysis of the results.

The lack of standardization of vision therapy techniques and methods, as well as differences in the frequency and duration of vision therapy, make it difficult to make generalizations about the effectiveness of vision therapy from the results of a single study (Beauchamp, 1986).

Many vision therapy regimens incorporate non-optometric interventions such as general body movement, exercise, diet, and most importantly, standard healing education techniques. Studies reporting the results of such vision therapies are difficult to interpret, as the effectiveness of these therapies may be due more to non-optometric interventions such as B. Standard corrective education techniques applied than to the vision therapy itself. Furthermore, these other elements may be better provided by professionals who are not optometrists, such as e.g. B. healing teachers. Beauchamp notes that "one may legitimately question an optometrist's ability to work on such complex issues" outside of optometry (Beauchamp, 1986).

accommodation disorders

The term "accommodation" refers to the adjustment of the eye to see at different distances and is achieved by changing the shape of the lens through the action of the ciliary muscle, thus focusing a clear image on the retina. Accommodation deficits include excessive accommodation, inability to accommodate, insufficient accommodation, poorly maintained accommodation (Suchoff, 1986), and paresis of accommodation (Scheinman & Wick, 1994). Accommodative paresis, seizures, and poorly maintained accommodation are relatively uncommon, and accommodative insufficiency and inability are the two most common types of accommodative deficit.

Excess accommodative (also known as accommodative spasm) is a more accommodative response to a given stimulus than is considered normal (Suchoff, 1986). Accommodative inability (also called accommodative laziness) is defined as laziness to move from one level of accommodation to another (Suchoff, 1986).

Accommodative insufficiency is a condition in which the patient's range of accommodation is below that expected for their age (Suchoff, 1986). Clinical diagnosis can be made by direct measurement of the amplitude, for example using the "push-up" method, in which the fine print is brought closer to the eye until the print appears blurred. The clinical diagnosis can be made indirectly by certain forms of dynamic retinoscopy.

Poorly sustained accommodation is a form of accommodative insufficiency in which the amplitude of accommodation is normal under normal testing conditions, but reduces or becomes "inadequate" over time (Suchoff, 1986). The clinical diagnosis is made by symptoms together with certain dynamic retinoscopy techniques that sample the accommodative response over time while the patient maintains fixation and accommodation on a target.

Accommodative paresis (also called accommodative paralysis) is the inability to elicit an accommodative response (Scheiman & Wick, 1994). The disorder is usually the result of disease or trauma.

Symptoms common to all types of accommodation disorders are reduced near visual acuity, general inability to maintain near visual acuity, asthenopia, excessive eye rubbing, headache, periodic blurred distance vision after a prolonged near vision, periodic near double vision, and excessive vision Fatigue at the end of the day (Suchoff, 1986).

The optometric literature proposes a variety of tests to detect the presence of accommodation disorders. Standardized test methods, normal values, and controlled studies are lacking for many of these tests. The sensitivity, specificity, and positive and negative predictive values ​​of accommodation tests remain undefined. Beauchamp (1994) states that "[a]comfort impairments/'disability', convergence abnormalities, and tracking impairments or smooth tracking have not been defined or demonstrated beyond vague hints. Indeed, studies carefully controlled tests do not reveal these alleged deficiencies.

These tests may not adequately differentiate between abnormal and normal children. For example, a New York State vision screening battery that tested visual efficiency and perceptual function identified 53% of an unselected group of 1,634 schoolchildren as "abnormal" (Visual Development Task Force, 1988). The literature on vision therapy for learning disabilities has been undermined by a "poor assessment of what constitutes normal variation" (Levine, 1984).

Press (1993) described tests used to assess accommodative ability in a school-age child. This includes testing the range of accommodation, which is clinically determined using the push-up or minus lens-to-blur method. Accommodation delay, an index of near-point accuracy, is primarily determined by the monocular estimation method (MEM) of near-point retinoscopy. As the child reads words binocularly into a target attached to a retinoscope, the examiner briefly places lenses in front of one eye to confirm the estimate of movement. Other methods of assessing delay include book retinoscopy, which is essentially the same as MEM except that the examiner notes the answer while the child continues to read a story; and bell retinoscopy, in which the examiner observes the change in reflex when a broken bell is brought toward the child and then withdrawn. Capacity and resistance tests are carried out with lens wings of +/-2.00 diopters and numbers 20/30. The diagnosis of an accommodation disorder depends on the number of lens rotation cycles that can be corrected in a given time.

Scheiman and Wick (1994) described general treatment strategies for patients with accommodative dysfunction. First, the optician must correct any refractive errors, including farsightedness (farsightedness), nearsightedness (nearsightedness), anisometropia (marked difference in the refractive power of each eye), and astigmatism. Although any refractive errors found must be corrected to improve visual acuity, there is little evidence that refractive errors are the cause of vision problems. Studies in age-matched populations have failed to show significant differences in the prevalence of refractive errors between children with reading difficulties and children without such problems (Coleman, 1972; Helveston, 1985; Hoffman, 1980).

Second, additional lenses are used to correct accommodation defects (Scheiman and Wick, 1994). Accommodative insufficiency and poorly maintained accommodation are thought to respond to additional positive lenses, as they are believed to stimulate accommodation. Patients with accommodation weakness and excess accommodation are less likely to benefit from additional lenses.

Third, vision therapy is used to restore normal accommodation disorder. According to Scheiman and Wick (1994), vision therapy is generally necessary in the treatment of accommodative excess and incapacity and is also important in many cases of accommodative insufficiency and poorly maintained accommodation.

Press (1993) described the components of vision therapy for accommodative dysfunction. He stated that the main technique used to correct accommodation disorders is "accommodative rock". This can be achieved by changing the power of the lens or by changing the fixation distance. Accommodative rocking with lenses is typically performed with loose round plastic lenses (best used in the monocular phase) or with flipper-mounted lenses (best used in the binocular phase). Swinging with glasses is believed to increase a child's ability to focus while reading for long periods of time.

Accommodative rocking by changing fixation distance is performed using large and small Hart diagrams consisting of ten rows of ten letters each (Press, 1993). The letters on the large Hart chart have a visual intensity of 20/20 at a distance of 20 feet. The Small Hart Chart is a small version of the Large Hart Chart. Children using these charts practice keeping their places as they move from far to near. Rocking in this manner is believed to enhance the child's ability to maintain precise focus when accommodation is alternately stimulated and inhibited, as is the case when a child is copying from a blackboard.

The general advance in therapy is to start with monocular activities and then progress to biocular and then binocular activities (Press, 1993). Monocular activities are performed with a patch. Biocular activities are performed with a loose positive or negative lens in front of one eye and a loose prismatic lens in the other eye to dissociate the Hart diagram. Binocular activities are generally performed with lenses attached to flippers.

Symptoms of accommodative insufficiency include blurred vision, headaches, eye strain, double vision, reading problems, fatigue, difficulty focusing from one distance to another, and sensitivity to light (Scheiman & Wick, 1994). Patients may also complain of a lack of concentration, loss of comprehension over time, and words that move around the page. All these symptoms are associated with reading or other close work. Some patients with accommodative insufficiency are asymptomatic. In such cases, the most likely explanation is avoiding reading or other close work. In such a case, avoidance should be considered a symptom and, according to Scheiman and Wick, is as important a reason for recommending treatment as any other symptom associated with accommodative insufficiency.

The most characteristic sign of insufficiency of accommodation is an amplitude of accommodation below the limit of the expected value for the patient's age. Scheiman and Wick (1994) suggested using the Hofstetter formula to determine a patient's lower limit, which states that the lower limit is equal to 15 - 0.25 (patient's age). If the amplitude is 2 diopters or more below this value, it is considered abnormal.

In 1922, Duane was the first to describe vision therapy as a method of curing "subnormal accommodation" or accommodative insufficiency as it is known today. In 1942, Hofstetter recommended that "exercises" be used to improve function where there is evidence of poor control of accommodation. However, none of these papers provided information on treatment methods or efficacy. As Suchoff and Petito (1994) noted, until relatively recently, many clinicians performed various accommodative functions despite a lack of evidence, other than anecdotal evidence or simple case reports, that accommodative function could be improved.

Several studies have been cited as evidence that subjects can be taught to voluntarily control their accommodation (Marg, 1951; Cornsweet & Crane, 1973; Randle & Murphy, 1974; Provine & Enoch, 1975). Each of these studies involved a small number of normal subjects. Because these studies included normal individuals, they do not show that individuals with accommodative dysfunction can improve their accommodative abilities through exercise. Furthermore, the results of these studies may not even apply to the majority of normal individuals, since the study subjects were selected from groups expected to have maximal accommodative capacities. In one study, subjects were selected on the basis of their "reported ability to change housing voluntarily" (Marg, 1951). The other studies (Cornsweet and Crane 1973, Rundle and Murphy 1974, and Provine and Enoch 1975) included young, college-age subjects whose accommodative capacity was considered normal.

In 1951, Marg noted the existence of voluntary stimulation and inhibition of accommodation. He instructed seven subjects to look closer and then further away at an object placed between 0.20 diopter and 5.00 diopter lenses. Six of the 7 test persons showed different degrees of voluntary accommodation. Several study participants reported symptoms when trying to stimulate accommodation. Marg (1951) interpreted these findings to support the theory that the symptoms arose from the need to make an effort to improve the accommodation reflex. She postulated that training in the control of voluntary accommodation may alleviate symptoms in patients with defective reflex accommodation.

Cornsweet and Crane (1973) used auditory and visual biofeedback to train individuals to voluntarily control accommodation. In the first experiment, 2 subjects were fitted with headphones. One tone, the pitch of which was adjusted by the researchers, was delivered to one ear, while a second tone, the pitch of which was controlled by the subject's adaptive response (measured with an infrared optometer), was delivered to the other ear. Subjects were asked to match the pitch between the two ears. After about 3 hours of practice, both subjects were able to solve the task. Cornsweet and Crane (1973) conducted a second experiment with the 2 subjects who participated in the first experiment to determine if they could voluntarily control accommodation in a different situation. Subjects looked at 2 horizontal lines on an oscilloscope screen. The experimenter fixed the position of one of the horizontal lines, and the position of the other horizontal line was controlled by the subject's accommodative response measured with an optometer. Subjects were asked to place one line on top of the other. Both subjects were able to perform this task after only a few seconds and demonstrated that the accommodation control they had learned could be easily transferred to new stimulus conditions.

Subsequently, Randle and Murphy (1974) conducted an experiment to determine which components of voluntary control of accommodation could be improved by visual biofeedback. Four college students were asked to practice following sine or square wave stimuli of different lengths. Students were tested every 3 waking hours for 7 days. Although the latency (reaction time) of the accommodative response remained constant over the 7 days, some students were able to increase the rate (speed) of their accommodative response with practice. The students were able to improve the gain (magnitude) and phase lag (reduced difference between stimulus and response waves) of their responses. Randle and Murphy showed that the speed, gain, and phase lag of the accommodative response can be improved with practice.

Provine and Enoch (1975) also conducted an experiment to show that individuals can learn to control their adaptive responses. Subjects had -9.00 diopter contact lenses placed in one eye while viewing a distant target and were instructed to focus on the target until they could see it clearly. After practice, all subjects were able to focus through the lens on the target. They found that once voluntary accommodation was learned, it could be activated on command, even in total darkness.

A second set of studies has attempted to determine whether patients with accommodation deficits improve after vision therapy (Liu et al., 1979; Bobierand Sivak, 1983; Daum 1983a; Daum, 1983b; Duckman, 1984; Hung et al., 1986; Cooper et al, 1987; Russelland Wick, 1993; Al-Qurainy, 1995). Most of these studies included a small number of patients and none included a control group. Because these studies were not controlled, there is no way of knowing whether the results could be due to various sources of bias, such as regression, natural history of the disease, placebo effects, investigator bias, or patient desire. to report improvements to the therapist

Liu and colleagues (1979) observed the accommodative response of 3 patients undergoing vision therapy for accommodative insufficiency and inability. Accommodation responses were measured using an infrared dynamic optometer, an instrument that electronically measures the various dynamic components of accommodation. Each patient was prescribed standard optometric vision therapy for 20 to 30 minutes daily. Patients' accommodation responses were measured prior to treatment and weekly thereafter. After 4 to 7 weeks of training, all 3 patients reported a significant improvement in amplitude and accommodative capacity, and a reduction or elimination of symptoms. Patients were found to have an increased rate of accommodative response to changing stimuli as measured by the dynamic optometer. A reduction in response latency was also observed in one patient.

Bobier and Sivak (1983) performed a similar experiment using a different objective means to measure the accommodation response. Five patients with accommodative disability were included in the study. Four patients were prescribed standard home vision therapy for 20 minutes per day and the fifth patient was an untreated comparator. Dynamic photorefraction was used to measure objective improvements prior to the training period and weekly thereafter. Clinical findings were also monitored weekly. Training ended after the subjects reached a predetermined minimum performance criterion. Three of the 4 treated patients showed statistically significant improvements, while no improvement was observed in the untreated patient.

Duam (1983) reviewed the medical records of 114 patients who were referred to a university binocular vision clinic and who were subsequently diagnosed with accommodation disorder. 96% of these patients were diagnosed with insufficiency of accommodation or accommodation disorder. Most patients have also been diagnosed with other vision problems. Patients received standard office vision therapy every 1 to 2 weeks and were prescribed vision exercises 3 times per week to perform at home. The median duration of treatment for treatment of accommodative symptoms alone was 3.7 weeks; The total duration of treatment for vision problems for all patients was not reported. 94 of the patients completed the treatment. Of the patients who completed treatment, 53% were considered fully successful (defined as resolution of symptoms and signs of accommodation deficiency), 43% partially successful (with at least some reduction in signs or symptoms), and 4 % unsuccessful (no relief of signs). or symptoms).

To determine whether the results obtained were durable, the investigator examined mean accommodative range data from 24 patients followed for various periods of time after completion of vision therapy (Daum, 1983). The mean amplitude of accommodation had decreased by a mean of 2 diopters (from a mean of 12 diopters to a mean of 10 diopters), but the mean amplitude of these patients was greater than that of the patients before vision therapy (8 diopters). .

Duckman (1984) reported the results of vision therapy in 60 children with cerebral palsy, none of whom could clear (focus through) a +2 diopter lens and 31 of whom could not clear with a 2 diopter lens. . (The inability to clean the lenses +/- 2 diopters is a sign of accommodative insufficiency.) Patients received standard vision therapy for 10 to 30 minutes, 3 to 4 days a week for 1 year. Of the 60 children, only 36 completed the therapy. The study did not report whether dropouts were due to lack of improvement. Of the children who completed therapy, 20 were able to clear the +2 diopter and -2 diopter lenses. A significant increase in the range of accommodation was reported in 34 of the 36 children. The author concluded that the results suggest that amplitude and accommodative capacity in children with cerebral palsy could be improved by standard vision therapy techniques, although he acknowledged that this study had significant shortcomings.

A third set of studies has attempted to show that improvements in accommodation elicited by vision therapy lead to improvements in performance on various tasks. Weisz (1979) examined the results of vision therapy on near vision in children with accommodation deficits. A total of 28 children diagnosed with some type of accommodation disorder were divided into 2 groups matched by age and school level. One group received visual accommodative therapy and the other received perceptual motor training without accommodative therapy. Both groups received two 30-minute sessions per week and were treated for the same amount of time. All patients were assigned a paper-and-pencil task before and after training that required near-point fine discrimination to assess the transfer effects of accommodative therapy on this task. The group treated with accommodative therapy achieved a normal level of accommodation in an average of 4.5 sessions and showed a significant decrease in the number of errors on the paper-and-pencil task after therapy compared with the group receiving motor training. perceptual.

Although this study has been cited to support the conclusion that accommodative training improves accuracy in tasks involving close range performance, there are a number of issues that make interpretation of Weisz's study difficult. First, subjects were selected for the study if they met one or more of the 9 criteria for diagnosing accommodation disorders. Therefore, we do not know if the results could be biased due to differences in the nature or extent of the accommodation deficits between the two groups. Second, the children were not randomly assigned to the 2 groups, which raises the question of whether systematic assignment of the children to the 2 groups affects the outcome. Third, the outcome measures were not adequately described; For example, one measured outcome was reduced time to test completion, "adjusted for" the number of errors on the test; however, the document does not define how this adjustment was made. Fourth, there is no evidence that the paper-and-pencil test used to measure progress has a valid relationship between practical reading and writing tasks.

Symptomatic patients then received vision therapy and were reassessed on completion. Three of the symptomatic patients dropped out of the study before starting vision therapy and 1 did not complete the vision therapy program, leaving 17 symptomatic patients for analysis. Symptomatic patients with accommodation or vergence disorders received weekly 30-minute vision therapy sessions in the office for 8 to 16 weeks, supplemented by daily 15-minute exercises at home. Symptomatic patients who had both accommodation and vergence disorders received twice as much weekly vision therapy and daily home therapy. After vision therapy, a statistically significant proportion of symptomatic subjects shifted toward the mean of asymptomatic subjects for tonic accommodation (a measure of distortion of the accommodation system) and the slope of the fixation disparity curve (related to the "gain" or amplitude of vergence). In a large but statistically insignificant number of symptomatic patients, the slope of the accommodative/stimulus response curve (related to gains in accommodation), the CA/C ratio (related to gains in accommodation/vergence interaction) shifted toward the mean for normal asymptomatic patients. subjects. All symptomatic patients had higher rates of monocular accommodative change (a measure of accommodative ability) after vision therapy. Significant reductions in symptoms were reported in 9 patients. To determine whether changes in these parameters persisted, 3 symptomatic patients were reassessed 6 to 9 months after vision therapy (Hung, 1986). In each of the 3 subjects, all but 1 of the measured parameters remained close to the value obtained immediately after completion of vision therapy. The parameter that changed after long-term follow-up was different for each of the 3 subjects.

However, the study by Hung and his colleagues had serious limitations. The study lacked an appropriate control group (asymptomatic college students were only used to establish norms for parameters examined in the study, and symptomatic college students were not assigned to treatment and comparison groups), and only 3 patients were followed up. to determine if changes in accommodative ability after vision therapy were durable. Furthermore, the accommodative measures that changed after vision therapy were not the same as the accommodative measures, which were found to be significantly different between asymptomatic and symptomatic subjects. Different levels of accommodative capacity were found to persist in each of the 3 subjects observed long-term.

Scheiman et al. (1998) demonstrated that accommodation disorders were significantly less common in older children than in younger children, suggesting that in most affected children the condition resolves spontaneously with age or that measurement of accommodation disorders in younger children it is not reliable. The fact that the verbal and numerical format of the accommodation tests caused problems in younger children suggested that measures of accommodation deficiency before and after exercise were more reliable in older children and young adults than in younger children.

The literature on the efficacy of vision therapy for ocular motor disorders and accommodation disorders is largely characterized by anecdotes, case reports, or case series with a small number of cases. Because case series are by definition uncontrolled, their results do not allow one to determine whether improvements that occur are due to therapy or are an artifact of maturation effects, trial-and-repeat effects, and nonspecific gains. that were accumulated simply by the giving of gifts. more attention to a child (Levine, 1984). Interpretation of these case series is also hampered by the relative lack of knowledge about the natural history of untreated visual impairment.

Amblyopia

Amblyopia is a visual impairment in an eye that did not develop normal vision in early childhood (AAO, 1992). It is sometimes called "lazy eye." It is estimated that the prevalence of amblyopia is at least 2%. There are 3 main causes including image loss (eg, congenital cataracts, blepharoptosis, corneal scarring), anisometropia (unequal refractive error in the 2 eyes), and strabismus (misalignment of the visual axes of the eyes). Accepted treatment methods include optical correction, occlusion, optical defocusing (also called cycloplegic defocusing or atropinization).

Amblyopia is distinct from suppressed squint and abnormal retinal correspondence (ARC), which are also commonly associated with abnormal visual experiences, although unlike amblyopia, they are often the result of intermittent squint. Suppression of strabismus and ARC are not defects but adaptations of binocular vision; they can help the affected individual by eliminating diplopia without undermining the ability for normal visual function. In contrast, amblyopia is of no value to the affected subject (Greenwald & Parks, 1994).

There is no evidence that vision training is equal to or superior to occlusion therapy in the treatment of suppressive amblyopia in children.

Although the term "amblyopia" meant "impaired vision" for many centuries, today the word has become synonymous with oppressive amblyopia in children. Suppression amblyopia refers to the suppression of central vision in one eye, when the images in the two eyes are so different that they cannot be merged into one.

Amblyopia is often accompanied by strabismus and is most effectively treated with occlusion therapy. As one authority stated, "complete occlusion of the preferred eye is the most effective method of treating strabismus amblyopia" (Greenwald and Parks, 1994). In occlusion therapy, the closed eye is deprived of all vision during the day, except for a brief period in which the child has the opportunity to maintain the closed eye's ability to set the degree of preference for one eye or another. another and for judge. The usual method of occlusion is a patch that is adhered to the skin around the eyelids.

Amblyopia can also accompany other causes of poor vision, such as: B. congenital cataract, pronounced anisometropia, or corneal scarring. In children with amblyopia and straight eyes, partial occlusion is the preferred treatment method. According to Greenwald and Parks, "[p]art-time occlusion is an appropriate therapy for straight-eyed amblyopia or for maintaining good vision after completion of primary treatment."

In some cases, amblyopia can be effectively treated by creating blurred vision in the preferred eye (Greenwald and Parks, 1994). This is most commonly accomplished by creating cycloplegia in the non-amblyopic eye through the administration of atropine. Blur can also be created with glasses or contact lenses.

Occlusion and optical methods of treating amblyopia work by forcing the patient to be visually dependent on an eye with reduced visual acuity and allowing the undisturbed visual experience to improve the functioning of the amblyopic eye. "This strategy undoubtedly works in the vast majority of cases, even if the amblyopic eye initially functions very abnormally" (Greenwald and Parks, 1994).

Despite the effectiveness of occlusion therapy, a variety of other approaches have been proposed to treat amblyopia, including vision therapy. However, there is no reliable evidence that vision therapy is superior to or as effective as occlusion therapy in the treatment of amblyopia. As one authority noted, "Occlusion therapy for amblyopia has been in use for more than 2 centuries and, despite its many disadvantages, is still without equal" (Greenwald and Parks, 1994).

The AAO concluded that vision therapy in the treatment of amblyopia is of "little clinical value" (AAO, 1992). The AAO Preferred Practice Pattern for Amblyopia states: "Eye range-of-motion exercises, 'passive' occlusion, or methods to stimulate or suppress vision using flashing lights or high-contrast rotating patterns have not been validated as clinically effective in controlled studies."

In contrast, the AOA has concluded that vision therapy has a place in the management of patients with amblyopia. The AOA Optometric Clinical Practice GuidelineCare of the patient with amblyopia(1994) state: "[a]ctive therapies of monocular and binocular amblyopia, in contrast to passive management (eg, occlusion), reduce the total treatment time required to achieve the best visual acuity" and that " are designed to address deficits that address four specific areas: eye movement and fixation, spatial awareness, accommodative efficiency, and binocular dysfunction.According to an AOA position statement on vision therapy for amblyopia, "[l] The most frequently encountered amblyopia generally requires 28 to 40 hours of outpatient therapy."

Garzia (1987) and Ciuffreda (1991) reviewed the literature on the effectiveness of vision therapy for amblyopia. Although both authors advocate the effectiveness of vision therapy for amblyopia, these reviews indicate that the evidence for the effectiveness of vision therapy for amblyopia consists almost entirely of case reports and small uncontrolled case series (Kageyama et al. Loomis, 1980; Wick, 1973; Selenow and Ciuffreda). , 1983; Ciuffreda et al 1979 Etting 1978 Jenkins and Pickwell 1982 Shippman 1985 Francoisand James 1955 Leyman 1978 Thamand Comeford 1983 Selenow and Ciuffreda 1986 Griffin et al 1978 van Noorden et al., 1970; Gould et al., 1970; Callahan and Berry, 1970 ; Pickwell, 1976; Lowndes-Yates, 1977; Banks et al., 1978; Campbell et al., 1978; Brown, 1980; Willshaw et al., 1980 Doba 1981 Lennerstrand et al. 1981 Dalziel 1980 Carruthers et al. 1980 Southwaite et al. 1981 Nyman et al. 1983 Lennerstrand and Samuelsson 1983 Lennerstrand and Lundh 1980 Wick et al., 1992; Saulles, 1987). The only comparative study cited by Garzia found no difference in treatment efficacy between vision therapy with occlusion and occlusion alone (quoting Francois and James (1955)). Two other small case series on vision therapy for amblyopia have been published since Garzia's 1987 review (Wick (1992); Saulles (1987)). Both studies looked at the treatment of amblyopia in people aged 6 years and over, and both studies failed to compare vision therapy and occlusion with occlusion alone.

In a review of the treatment of amblyopia, Greenwald and Parks (1994) stated that "a rigorous evaluation of the benefits [of vision therapy] has not been performed." The authors cited the story of the CAM stimulator for amblyopia as an example of the dangers of relying on uncontrolled case reports and case series. Researchers at the University of Cambridge have developed this device that provides visual stimulation to a treated amblyopia. The first series of cases reported spectacular results. However, Greenwald and Parks noted that "[when] efforts were made to confirm early findings in carefully controlled studies, no significant difference between treatment and control groups could be demonstrated."

Furthermore, Greenwald and Parks argued that vision therapy is not necessary for the treatment of amblyopia because "it is quite possible that the day-to-day demands and experiences of the patient's environment are as effective in this regard as those developed by the therapist. "It can be".

Eye Tracking Devices to Treat Amblyopia

NovaSight offers the CureSight system, a non-invasive cloud based eye tracking monitoring for amblyopia treatment that offers patients an alternative to standard eye patch treatment. The CureSight system allows the patient to use a portable display with NovaSight-supplied 3D glasses that use eye-tracking technology when the patient watches videos and TV shows and uses social media and online streaming services at home. The CureSight system uses eye-tracking technology to blur the dominant eye's center of vision based on gaze position, while keeping the rest of the image sharp. At the same time, the amblyopic eye sees a clear view of the content being viewed. This encourages the brain to fill in the blurry information from the amblyopic eye, improving its visual acuity and developing stereoscopic acuity as the eyes learn to work together. The system can automatically adapt the treatment plan to the patient's progress based on eye-tracking information and artificial intelligence (AI) algorithms, and provide reports to caregivers via a mobile app and cloud-based platform. . According to NovaSight, the CureSight is a research device restricted by federal (or US) law for research purposes (NovaSight, 2021). FDA, could lead to agency approval of the technology.

Occlusion therapy for the treatment of sensory deprivation amblyopia

Sensory deprivation amblyopia (SDA) develops due to an obstruction in the passage of light as a result of a condition such as cataracts. The obstruction prevents the formation of a clear image on the retina. Sensory deprivation amblyopia can be resistant to treatment, resulting in a poor vision prognosis; and probably represents less than 3% of all cases of amblyopia, although exact estimates of its prevalence are unknown. In developed countries, most patients present before the age of 1 year; In less developed parts of the world, patients are likely to be older at the time of presentation. The mainstay of treatment is cataract removal and then closure of the better-seeing eye, but therapies vary, can be difficult to administer, and have traditionally been thought to produce disappointing results. In a Cochrane review, Antonio-Santos et al. (2014) evaluated the effectiveness of occlusion therapy in SDA to determine realistic treatment results. When data were available, these investigators reviewed the evidence for dose-response effects and assessed the effect of duration, severity, and causative factor on the magnitude and direction of treatment effect. These investigators searched CENTRAL (containing the Cochrane Eyes and Vision Group's Trials Register) (The Cochrane Library 2013, Issue 9), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to October 2013), EMBASE (January 1980 to October 2013), the Latin American and Caribbean Literature in Health Sciences (LILACS) (January 1982 to October 2013), PubMed (January 2013). 1946 to October 2013), the metaRegistry of Controlled Trials (mRCT) (www.controllered-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). They did not use date or language restrictions when searching for court cases electronically. The last search of the electronic databases was on 28 October 2013. These investigators included randomized and quasi-randomised controlled trials in participants with unilateral ADS with visual acuity less than 0.2 logMAR or equivalent. They did not specify any restrictions on enrollment based on age, gender, race, comorbidities, medication use, or number of participants. Abstracts of studies identified by the electronic search were independently assessed by two reviewers. They did not identify any studies that met the inclusion criteria specified in the protocol for this review. The authors concluded that they found no evidence of the effectiveness of any treatment for ADS. Furthermore, they stated that future randomized controlled trials are needed to assess the safety and efficacy of occlusion, duration of treatment, actual vision achievable, impact of age of onset and extent of visual defect, optimal occlusion scheme. and the factors associated with satisfactory and satisfying vision. unsatisfactory results using different interventions for SDA.

Online digital programs to treat amblyopia

RevitalVision, formerly NeuroVision, (Talshir Medical Technologies Ltd.) has received FDA clearance for its vision training software program that provides therapeutic vision training at home for patients 9 years and older with amblyopia. RevitalVision offers a treatment option to improve vision in amblyopic adults when patch therapy is no longer effective. RevitalVision's vision training web application technology platform is delivered from the patient's home computer during three to four 30-minute home training sessions per week for three months. According to the manufacturer, repeated practice of defined visual tasks trains the brain to process visual information more efficiently. RevitalVision's specialized algorithms analyze performance and continually adjust workouts to improve vision, adapting to the specific needs of patients. A physician can closely monitor the patient's progress through a personal office visit to measure actual vision improvement after 20 and 40 sessions, remotely monitor the patient's training activity by actively accessing the management portal and receive automated system reports.

Yalcin and Balci (2014) conducted a prospective study to evaluate the efficacy of neural vision therapy, also called perceptual therapy, in improving best-corrected visual acuity (BCVA) and contrast sensitivity function in amblyopic patients. The study enrolled 99 subjects between the ages of 9 and 50 previously diagnosed with unilateral hyperopic amblyopia. Subjects were divided into two groups, with 53 subjects (53 eyes) in the Perceptual Visual Therapy group and 46 subjects (46 eyes) in the control group. Because the nature of the treatment requires hard work and strict adherence, the authors enrolled the minimum number of subjects necessary to obtain statistically significant results. A statement of consent was obtained from all subjects. The phases of the study included an initial evaluation, a series of 45 perceptual vision therapy training sessions, and a final evaluation. BCVA and contrast sensitivity function at 1.5, 3, 6, 12, and 18 cycles per degree of spatial frequencies were obtained for statistical analysis in both groups. All subjects had follow-up visits within 4-8 months. With the exception of one study group subject and two control group subjects, all subjects had infantile occlusion. The study was not blinded. The Perceptual Learning Therapy Program (RevitalVision LLC) is a non-invasive, software-based, patient-specific, interactive perceptual learning tool based on visual stimulation. Facilitates neural connections at the cortical level through a computer-assisted visual training program that uses Gabor patches to improve contrast sensitivity and visual acuity. The results of the study group showed a mean improvement of 2.6 log lines of the minimum angle of resolution (logMAR) in visual acuity (from 0.42 to 0.16 logMAR). Contrast sensitivity function was improved at spatial frequencies of 1.5, 3, 6, 12, and 18 cycles per degree. The control group did not show significant changes in visual acuity function or contrast sensitivity. None of the treated eyes showed a decrease in visual acuity. Manifest refractions remained unchanged throughout the study. The authors concluded that the results of their study demonstrate the efficacy of cognitive therapy in improving visual acuity. The improvement in visual acuity by 2.6 logMAR lines is encouraging and consistent with the results of previous studies. However, long-term follow-up and further studies are needed.

Visual therapy in anisometropic amblyopia

In a systematic review, Hernández-Rodríguez and Pinero (2020) examined the evidence on the effectiveness of vision therapy in children and adolescents with anisometropic amblyopia. These investigators performed a search using 3 search strategies in 4 different databases (PubMed, Web of Science, Scopus, and PruQuest). The quality of the included articles was assessed using 2 tools to assess risk of bias, ROBINS-I for non-randomized intervention studies (NRSI) and ROB 2.0 for randomized clinical trials. The search yielded 1,274 references; however, only 8 of them met the inclusion criteria after full text review. The articles finally included included 2 RCTs and 6 NRSIs. These articles provided evidence of the effectiveness of vision therapy for the treatment of anisometropic amblyopia in children and adolescents. The risk of bias assessments showed a reasonable risk of bias for the RCTs, but a high risk of bias for the NRSI. A major source of risk of bias for NRSI was in the area related to outcome measurement due to the lack of double-blind studies. The authors concluded that active vision therapy is a promising therapeutic option for anisometropic amblyopia in children; However, there is still limited high-quality scientific literature on the subject. Therefore, further research is needed to improve our understanding of the effectiveness of treatment protocols involving vision therapy in amblyopia and to determine which neural mechanisms are specifically involved. Furthermore, these investigators suggested that combined vision therapy and patch treatment is a potentially more suitable therapeutic option for anisometropic amblyopia, allowing the clinician to optimize processing time, minimize the psychosocial effects of prolonged patch use, and improve adherence to therapy to improve and attract attention. to more visual abilities than just visual acuity (VA). This needs to be further investigated in future RCTs with stricter inclusion criteria and methods.

excess convergence

The AOA defines convergence excess as "a sensory and neuromuscular abnormality of the binocular visual system characterized by an excessive degree of convergence" (AOA, 1995). Convergence excess is a vergence abnormality in which the esophoria or esotropia is greater near than far. The diagnosis usually implies the presence of eso-nearfield deviation of at least 2 to 6 prism diopters (Shorter, 1993). Patients may have a higher than normal convergence to accommodation (AC/A) ratio.

Symptoms of excess convergence include diplopia, headache, asthenopia (eye spots), blurred vision, and avoidance or inability to maintain near visual tasks. Symptoms are often triggered after prolonged near vision tasks (AOA, 1995).

Textbooks and anecdotal accounts have advocated vision therapy as a treatment for overconvergence (see Shorter, 1993). The AOA guidance on over-convergence states that over-convergence is often successfully treated with therapeutic lenses and/or prisms, but ortho-optics/vision therapy may also be required (AOA, 1995).

The AOA states that 28 to 36 hours of vision therapy is normally required, but that a longer duration of treatment may be required for excessive convergence complicated by esotropia, oculomotor dysfunction, an accommodation disorder, other visual abnormalities, or associated conditions. such as stroke, head trauma, or systemic diseases (AOA, 1995).

Few clinical reports have been published on the effectiveness of vision therapy for convergent excess. In one of the few reports, Shorter (1993) described an uncontrolled retrospective study of the optometric records of 12 non-presbyopic patients with excessive convergence (Shorter, 1993). Subjects received different types and durations of vision therapy treatment and were treated by different physicians. Subjects received vision therapy office visits as often as once per week to once per month, with home exercise prescribed 4 to 6 days per week in addition to office therapy. Three of the subjects were also treated with bifocals. The median duration of vision therapy was 4 months. Of 11 subjects with symptom status recorded after treatment, 8 (73%) reported improvements in symptoms of headache, blurred vision, eyestrain, intermittent diplopia, and/or reading problems (Shorter, 1993). However, there were no statistically significant improvements in areas of vergence after vision therapy.

Due to limitations of the study design, no conclusions could be drawn about the effectiveness of vision therapy for excess convergence. In the absence of a control group, we cannot determine whether the improvements in the subjects could be due to placebo effects, regression phenomena, and/or the natural history of the disease (Shorter, 1993).

convergence insufficiency

According to AAPOS, convergence insufficiency is the inability to maintain binocular function (keep both eyes working together) while working in close proximity. “With convergence insufficiency, a misalignment of the eye occurs when focusing on close objects. Occasionally, in a patient with non-convergence, there is well-controlled intermittent near exotropia (outward rotation of the eye); however, with convergence insufficiency, the deviation is symptomatic and occurs spontaneously only when focusing on close objects” (AAPOS, 2020a).

There is consensus in the professions of optometry and ophthalmology that vision/orthoptic therapy is an effective treatment for convergence insufficiency. Early uncontrolled studies had shown that convergence insufficiency responded rapidly and reliably to simple exercises such as "push-ups" in almost all cases (Mann, 1940; Cushman, 1941; Lyle, 1941; Hirsch, 1943; Duthie, 1944; Mayou , 1945). ; Mellick, 1950; Passmore, 1957; Norm, 1966; Hoffman, 1973; Wick, 1977; Daziel, 1981; Kertesz, 1982; North, 1982; Patano, 1982; Cohen, 1984; Daum, 1984; Deshpande, 1991a; Deshpande, 1991b). The rapidity and consistency of this response made it less likely that the results of these uncontrolled studies could be due to bias such as regression to the mean, natural history of disease, or placebo effects, although these causes account for both bias and error. bias due to test. -Retest phenomena cannot be ruled out. More recently, controlled clinical trials have demonstrated the efficacy of vision therapy for convergence insufficiency.

Published clinical trials of orthotics/vision therapy for convergence insufficiency indicate that a limited number of physician visits are required to resolve convergence insufficiency. Published clinical studies of vision/orthoptic therapy for convergence insufficiency indicate that the average number of physician visits for convergence insufficiency is typically less than a dozen. Only Hoffman (1973) reported a much higher mean number of doctor visits (24); All vision therapy exercises were performed in the office. The orthoptic (ophthalmic) literature reports successful treatment of convergence insufficiency with fewer physician visits than the optometric vision therapy literature. Orthoptists/ophthalmologists rely more on home practice, while optometrical optical therapists tend to perform more therapy in the office.

Although not all of these studies described the specific vision therapy methods used, many reported successful treatment with simple exercises that can be performed at home after brief instruction.

Griffin and Grisham (1995) recommend office visits once a week to monitor patient progress, prescribe and teach new training procedures, and keep the patient motivated. The authors reported that, in their experience, most patients with exophoric convergence failure can be treated in 6 to 8 weeks with a home exercise program with regular physician visits, and that most patients with exophoric convergence failure exotropic convergence generally require longer periods of exercise, perhaps 8 to 10 weeks. or more. Grisham et al. (1991) studied the effectiveness of vision therapy in 4 patients with convergence insufficiency and 2 controls and found that vergences in treated patients improved to normal values ​​in a period of 5 to 8 weeks.

Treatment of convergence insufficiency can be completed in as little as 12 weeks. Christenson reported on a case study of a patient with convergence insufficiency who was treated with weekly physician visits and home exercise over a 10-week period (cited in Griffin & Grisham, 1995). Patano (1982) reported the successful treatment of 207 patients with convergence insufficiency with daily 20-minute home exercises for one month. Cohen and Soden (1984) reported the treatment of patients with convergence insufficiency with weekly 45-minute sessions in the office accompanied by home therapy. The average number of practice therapy sessions was 12.

Daum (1984) analyzed the results of vision therapy in 110 patients with convergence insufficiency from 2 to 46 years of age. Most of the training in this series of patients was done at home. The mean training time was 4.2 weeks. Dalziel (1981) reported the successful treatment of 100 patients with convergence insufficiency with weekly visits to the physician and daily exercise at home. The researchers reported that the average duration of therapy was 6 weeks, with a range of 2 to 16 weeks, but found that the average patient only received two 45-minute sessions in the office.

Convergence insufficiency exercises can be performed at home and patients with convergence insufficiency should be transferred to a home program. Examining the comparative effectiveness of home therapy versus office treatments, Deshpande and Ghosh (1991) reported the success of vision therapy in 2162 patients with convergence insufficiency. Patients received 10 doctor visits or 3 weeks of exercise at home. They concluded that the response to therapy was "comparably equal" between the two therapies.

esotropía

Esotropia, or convergent squint, is an apparent inward deviation of the eye. It can be present at birth (congenital) or appear later in life (acquired). Esotropia can be constant or intermittent. Alternating esotropia refers to the displacement of esotropia from one eye to the other. Vision/orthoptic therapy has been used in the treatment of esotropia.

Active vision therapy (also known as vision training, orthoptics, eye training, and eye exercises) includes a variety of non-therapeutic approaches, including biofeedback, eye movement exercises, and more complex training with optical and electronic instruments (Hoffman, 1987).

Strabismus is an apparent deviation of the visual axes, commonly known as rolled or crossed eyes. Esotropia is a type of strabismus, in which there is a marked inward deviation of the eyes. The deviation in strabismus can occur in multiple directions, it can be distant, close, or both, and it can be intermittent or constant.

A Pediatric Ophthalmology Committee of the AAO Care Quality Committee published a Preferred Practice Pattern on Esotropia (AAO, 1992). Treatment modalities for this disorder include refractive error correction (75% success; should be used for clinically significant astigmatism, anisometropia, hyperopia, and/or near-to-far mismatch), miotics (anticholinesterase agents that reduce the effort of accommodation stimulating the decrease of the cilia). muscle contraction), prism therapy (for small symptomatic esosdeviations and to alleviate diplopia in older children who have acquired esotropia after exotropia surgery), surgery (should only be performed when the most conservative methods fail, about 25% of patients).

There is a lack of evidence on the effectiveness of vision therapy for esotropia. In the clinical practice guideline for the treatment of esotropia, the AAO (1992) concluded that orthoptic/active vision therapy is "no longer considered effective" in the treatment of esotropia and "its use should be discouraged".

Several authors of reviews of the optometric literature on the effectiveness of vision therapy for esotropia have drawn conclusions about overall effectiveness by summarizing "success rates" from observational studies of vision therapy for esotropia and by summarizing studies of Different designs, strengths, and weaknesses (Flax, 1978), no attempt is made to critically appraise the inherent limitations of these studies or the difficulties in drawing conclusions about the effectiveness of vision therapy from them. The authors refer to 'controlled' studies, which implies that these studies are controlled clinical trials, although these studies were in fact observational studies with non-contemporaneous comparison groups.

Studies should be grouped by design, with the strongest studies (ie those studies that are designed to have the least potential for bias) being given the greatest weight (Anderson, 1990). The only prospective, randomized, controlled clinical trial published to date of optometric vision therapy for esotropia has found no benefit from active vision therapy (Fletcher, 1969). This study was ignored in reviews of the effectiveness of optometric vision therapy for esotropia.

Published case series on vision therapy for esotropia report widely different durations of treatment and frequencies of physician visits, with no consistent association between longer duration of treatment and frequency of physician visits with better outcomes. Cooper and Medow (1993) noted that "[o]thoptic orthoptic therapy is primarily administered to the patient at home, whereas optometric orthoptic therapy utilizes both office and home therapy."

Although the AOA states that treatment for intermittent esotropia requires 40 to 52 hours of office visits and the more common constant esotropia generally requires 60 to 75 hours of office treatment, their guidance provides no evidence to support this claim.

The literature on the effectiveness of vision therapy has reported an orthoptic treatment of esotropia that requires far fewer office visits. In a report on the treatment outcomes of 57 patients with esotropia, Wick (1987) reported a mean duration of treatment of 4.57 weeks for intermittent esotropia, with basic intermittent esotropia requiring treatment on average 1.5 weeks longer than intermittent esotropia with excess convergence. He found that "constant strabismus had a significantly longer course of treatment [an average of 6.65 weeks] than intermittent splinting." Forrest (1978) reported treatment of a patient with esotropia in 5 office visits (1 every 4 months) plus home exercise. Knapp (1971), reporting his experience in treating 139 patients with accommodative esotropia, reported that orthoptic training, when indicated, required as little as 1 week and up to "a couple of weeks". Griffin and Grisham (1995) state that most cases of overconvergence esotropia occur with a home training program with weekly field trials and training visits for 2–4 months, underdivergence esotropia for 3 to 4 months and esophoria for 8 to 12 months. months Office visits can be treated. They state that with basic esotropia, after 1 to 2 months of vision training, clinicians can determine which patients need surgery and which do not, stating that “if the strabismus patient has not achieved satisfactory binocular vision within 6 months , active vision training with compliance, we propose surgical evaluation and in most cases we support the surgeon's recommendation."

Kertesz and Kertesz (1986) report on an esotropia treatment that was completed in 9 orthoptic therapy visits. Layland (1971) reported that esotropia was treated in 15 visits. Fletcher and Silverman (1966), reporting the success rate in treatment of a series of more than 1000 consecutive cases of esotropia, noted that "long-term ortho-optics were not used". Lyle and Foley (1957) reported cases of postoperative esotropia requiring no more than 12 visits (13). Mann (1947) reported that treatment of esotropia required an average of 9 visits. Weinstein (1972) reported that treating esotropia and exotropia with Opto-Illuminator required only 5-6 sessions. Etting (1978) reported treatment of strabismus with twice weekly visits for 3 months.

There is no evidence that optometric orthoptics, which are largely performed in the office, are superior to orthopedic orthoptics, which are primarily performed by the patient at home. The results of long-term inpatient treatment of constant or intermittent esotropia have not been shown to be superior to home therapy with regular follow-up. Therefore, prolonged vision therapy/orthoptic treatment for esotropia is not only necessary for tests, but also from a medical point of view. Patients with esotropia can be transferred to a home vision therapy program with regular follow-up.

intermittent exotropia

Intermittent exotropia, a common type of horizontal squint, is an inconsistent outward deviation of one or both eyes. Intermittent exotopia manifests predominantly with distant fixation and may progress to near fixation over a variable period of time. Patients with intermittent exotropia are often asymptomatic. The most common presentations are parents reporting that the child has one eye closed when she walks in bright light or that an occasional deviation has been noted. However, various symptoms may be reported, including transient diplopia, diplophotophobia, micropsia, and complaints of eye strain, blurred vision, headache, and prolonged reading difficulty (Kaur and Gurnani, 2021).

The classification of intermittent exotropia based on distance and near deviations includes the following four types (Kaur and Gurnani, 2021):

• Basic type: when the difference between distance deviation and near deviation is less than 10 prism diopters. These patients have normal fusion, accommodation, AC/A ratio, and proximal convergence.
• Excess True Divergence: Based on a patch test, the distance deviation exceeds the near deviation by at least 10 prism diopters. These patients may be associated with a high or normal AC/A ratio. Patients with a high AC/A ratio have the potential for overcorrection when operated for distance deviation.
• Poor convergence: the deviation for near exceeds the deviation for distance by at least 10 prism diopters.
• Pseudodivergence Excess: When the distance deviation exceeds the near deviation by more than 10 prism diopters, but after monocular patch testing, the difference between the distance and near deviation decreases to less than 10 prism diopters. The patch test disrupts the associated higher tonic fusion convergence in these patients, and therefore an increase in near deflection is seen after this test, bringing the near deflection closer to the far deflection values. This was described by Kushner as persistent proximal fusion.

Coffey et al. provided evidence of the efficacy of vision therapy for intermittent exotropia. (1992) revised. Researchers identified and summarized evidence for the effectiveness of treatments for intermittent exotropia, including optical correction, prisms, occlusion, strabismus surgery, and vision therapy. The researchers concluded that the pooled success rates for vision therapy were higher than those for any other treatment. Coffey et al. however, he noted that "nearly all of the studies were retrospective, lacked the controls necessary to determine whether the conclusions were valid, contained subsample sizes so small that interpretation of the results is questionable, and suffered between-patient selection bias" . or results reported in a way that made interpretation difficult.”

Assessment of a patient's ability to control an intermittent exotropic shunt is generally done through subjective means such as observation of office monitoring, patient and/or family interviews for home monitoring, and reports of monocular closure. of the eye in bright light (Stathacopoulos, 1993). ).

The number of doctor visits required and the duration of treatment for a specific indication also differ significantly between orthoptists and vision therapists. As Cooper and Medow (1993) noted in a review of intermittent exotropia, "orthoptic orthoptic therapy is primarily administered to the patient at home, whereas optometric therapy utilizes both office and home therapy." on the effectiveness of orthoptic exercises reported in the orthoptic and optometric literature. The AOA, in its Clinical Practice Guideline on Strabismus (1995), stated that optometric vision therapy generally requires 25 to 75 hours of office visits. However, the duration of treatment reported in the literature varies widely, with no consistent relationship between the number of physician visits, duration of treatment, or transfer to home exercise programs, and treatment outcomes.

In a series of studies on the effectiveness of optometric vision therapy, Daum reported median treatment durations for intermittent exotropia of 4.3 weeks (Daum, 1984a), 5.5 weeks (Daum, 1984b), and 7.6 weeks ( Daum, 1984c). In the largest published study of vision therapy for intermittent exotropia, Patano (1982) reported an average duration of treatment of 1 month. The second largest study of vision therapy for intermittent exotropia by Cooper and Leyman (1977) reported a treatment duration of 12 to 15 weeks. Newman and Mazow (1981) reported the longest mean duration of treatment, reporting a mean treatment duration of 12 months. However, its reported success rate was below the average for all studies of vision therapy for intermittent exotropia.

The AAO Pediatric Ophthalmology/Squint Panel guidance on “Esotropia and Exotropia” (AAO, 2012) stated that “potential benefits of esotropia treatment include promotion of binocular vision and normal visual function in each eye. When binocularity is achieved, the number of surgical procedures throughout a lifetime and the overall cost to society can be reduced. Fusion and stereopsis are necessary for some careers and can also be useful in others, such as sports activities and activities of daily living. Furthermore, binocular alignment is important for developing a positive self-image and improves social interactions by normalizing appearance and eye contact. Potential benefits of exotropia treatment include promoting binocular vision and normal visual function in each eye. Normal binocular alignment promotes a positive self-image. After strabismus surgery, adults have reported an improvement in self-confidence, self-esteem, and interpersonal interactions... Wit H spectacle treatment is generally preferred over surgery because of the risk of subsequent esotropia and diplopia afterward. of the surgery. If the deviation is intermittent, many ophthalmologists delay surgery in young children with fusion to avoid complications related to postoperative esotropia. These complications include oppression, amblyopia, and loss of binocular vision, particularly stereoscopic acuity. This guideline did not mention vision therapy as a therapeutic option.

Hatt and Gnanaraj (2013) noted that the clinical management of intermittent exotropia [X(T)] has been widely discussed in the literature, but clarity regarding indications for intervention, the most effective form of treatment, and whether or not There is an optimal moment in the development of the disease in which treatment should be given. In a Cochrane review, these investigators analyzed the effects of various surgical and non-surgical treatments in randomized trials in participants with X(T), reported intervention criteria, and determined the importance of factors such as age in relation to outcome. These investigators searched the Cochrane Central Register of Controlled Trials (CENTRAL) (containing the Cochrane Eyes and Vision Group's Trials Register) (The Cochrane Library, Issue 4, 2012), MEDLINE (January 1966 to May 2012). , EMBASE (January 1980 to May 2012), Latin American and Caribbean Literature in Health Sciences (LILACS) (January 1982 to May 2012), the metaRegistro de Ensayos Controlados (mRCT) (www.control-trials .com), ClinicalTrials.gov (www.clinicaltrials.gov) and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). They did not use date or language restrictions when searching for court cases electronically. The last search of the electronic databases was on 4 May 2012. These investigators no longer searched the UK Clinical Trials Gateway (UKCTG) for this review. They handsearched the British Orthooptic Journal up to 2002 and the registries of the European Strabismus Association (ESA), the International Strabismus Association (ISA), and the American Academy of Pediatric Ophthalmology and Strabismus (AAPOS) meeting up to 2001. They contacted researchers who are working in the field for information on other published or unpublished studies. These investigators included randomized controlled trials ( RCTs ) of each surgical or non-surgical treatment of X(T). Abstracts of studies identified by electronic and handsearches were independently assessed by each reviewer. The authors' analyzes were then compared and the full articles of eligible studies were obtained. They found 1 randomized trial eligible for inclusion. This study showed that unilateral surgery was more effective than bilateral surgery in correcting the basic type of X(T). The authors concluded that the available literature consisted mainly of retrospective case reviews that are difficult to reliably interpret and analyze. The 1 included randomized study found that unilateral surgery in basic X(T) is more effective than bilateral surgery. However, in all identified studies, measures of severity, and therefore intervention criteria, were poorly validated and reliable natural history data did not appear to be available. They stated that there is therefore an urgent need for improved measures of severity, a better understanding of the natural history, and carefully designed treatment clinical trials to improve the evidence base for the management of this condition. Vision therapy was not mentioned as a therapeutic option in this review.

Joyce et al. (2015) noted that the evidence for the efficacy of interventions to treat childhood X(T) is unclear. These investigators conducted a systematic review to locate, assess, and synthesize evidence of efficacy, including 12 electronic databases, supplemented by manual research and expert contacts. They included RCTs, quasi-experimental, and cohort studies with a comparison group evaluating interventions for excess divergence, sham excess divergence, or basic type X(T) in children up to and including 18 years of age followed up for at least 6 months. A double extraction of data and a critical evaluation were carried out, and a narrative synthesis was carried out. A total of 11 studies met the selection criteria; 7 examined the comparative efficacy of 2 surgical procedures; 4 compared surgery with other procedures, including botulinum toxin A therapy, orthoptic exercises, occlusion, binocular vision training, and watchful waiting. The retrieved evidence was of limited size and quality, with differences between studies in outcome assessment and the most appropriate time to measure long-term outcomes. When comparing unilateral recession/resection (R&R) with bilateral lateral rectus recession (BLR), mixed results were found for improving the angle of deviation, making it difficult to recommend either surgical option with confidence. Although non-surgical interventions appear less effective in improving deviation angle, they are rarely associated with adverse outcomes. The authors concluded that, given the limited evidence base, better designed studies are needed to address the question of the most effective management for the treatment of childhood X(T); More importantly, it requires consensus on what constitutes a successful outcome and agreement on how it should be measured.

The American Association for Pediatric Ophthalmology and Strabismus (2015) stated that X(T) can be congenital or acquired. Acquired forms of X(T) include intermittent X(T), sensory X(T), and consecutive X(T) (exotropia that develops after surgery to treat strabismus). Non-surgical treatment of X(T) may include spectacles, and in some cases, patch therapy may be recommended. If the eyes are misaligned more often than they are straight, eye muscle surgery may be recommended to realign the eyes. Exercise or vision therapy have been suggested to treat some cases of intermittent X(T), but have not been shown to effectively treat intermittent X(T).

AAPOS (2019) notes that exercise or vision therapy have not been shown to be effective in treating intermittent exotropia.

An updated review of "Causes of horizontal strabismus in children" (Coats and Paysse, 2021) includes treatment of intermittent exotropia. The authors state that “a variety of treatments have been proposed for intermittent exotropia. However, no single treatment has been shown to be superior in all cases, and long-term follow-up shows a high recurrence rate, regardless of the initial therapy. As a general rule, if the exotropia is infrequent, the prognosis is normal binocular vision and stereopsis is good. Intervention in these children should be decided on a case-by-case basis, at the discretion of the physician and the parents." The authors state that "active vision therapy consists of a combination of eye exercises and vision training maneuvers. This therapy can be prescribed to be performed at home or in weekly or more frequent meetings in the office. In a randomized controlled trial of 221 children (9 to 17 years of age), an intensive in-office vision therapy program with home reinforcement was more effective in reducing signs and symptoms than multiple home therapies. "Active" vision therapy consisted of a rigorous protocol, including a variety of exercises to improve vergence and accommodation. Placebo therapy consisted of procedures designed to provide true vision. Simulate therapy/orthoptics without the expectation of vergence, accommodation, or saccadic function are necessary to determine whether office therapy is superior to equally intensive home therapy."

Kaur and Gurnani (2021) state that treatment for intermittent exotropia ranges from observation to surgical or non-surgical intervention, depending on the deviation, control, and patient discomfort. Supporting the detection of double vision in misaligned eyes and creating fusion reserves to control exodeviation. The authors discuss various non-surgical treatment options, including:

• ametropia correction
• Orthooptics – This can be used to improve deviation control. The objective is to make the patient aware of the manifest deviation. Convergence exercises are useful for patients with a remote near the point of convergence or for patients with weak fusion convergence amplitudes. Active antisuppression and diplopia awareness techniques are useful in suppressed patients.
• Overcorrected negative lenses
• partial occlusion
• Prismotherapy

Kaur and Gurnani (2021) state that if exotropia persists, orthoptic exercises, including antisuppression exercises or fusion exercises, should be continued until alignment is achieved.

Non-strabismic disorders of binocular vision

The diagnosis of binocular vision disorder is a problem of visual efficiency.

Non-strabismic binocular vision disorder is defined as a condition in which a person must exert excessive effort to maintain continuous single binocular vision (Suchoff, 1986). Non-strabismus binocular vision disorders are related to accommodation deficits, problems with fusion convergence (ie, divergence and convergence), or both. A binocular vision disorder is always secondary to these diagnoses. A diagnosis of binocular dysfunction is secondary to diagnoses of convergence, divergence, or accommodative function.

A non-squint disorder of binocular vision is distinguished from intermittent squint, a condition in which there is at least one overt intermittent rotation of the eyes. In practice, a patient who has continuous comfortable binocular monocular vision may exhibit non-strabismic binocular vision impairment due to fatigue or the optical or cognitive demands of a particular situation. Similarly, in demanding situations such as B. prolonged reading, he shows intermittent squint.

The main consequence of a patient with non-strabismus binocular vision disorder is asthenopia, a sensation of ocular or visual discomfort (Suchoff, 1986). The patient with asthenopia may complain of eyestrain, eye pain, frontal and occipital headaches, and eyes that tire easily.

According to the optometric literature, non-strabismus binocular vision disorders are associated with accommodation deficits, problems with fusion convergence (ie, divergence and convergence), or both (Suchoff, 1986). Thus, vision therapy aims to improve binocular vision by increasing the efficiency of the accommodation system and/or improving fusion vergences. Therefore, the efficacy of vision therapy for a non-strabismus binocular dysfunction disorder would depend on its efficacy for the underlying causative disorder.

nystagmus

Congenital nystagmus is an ill-defined abnormality present at birth or detected in the first months of life during which visual fixation develops (Dell'osso, 1991; Abplanalp, 1983). Most people affected by congenital nystagmus can identify a visual field in which the intensity of the nystagmus, but not the frequency, is minimal. This particular gaze position is known as the null zone, which is usually stable for long periods of time in most patients. These individuals often use sustained head rotation to bring their eyes to a position of lower nystagmus, allowing them to keep their eyes relatively stable when looking directly toward the midline of the body. Traditional therapies for congenital nystagmus rely on the existence of a null zone and generally only reduce eye movements in the gaze position (Dell'osso, 1991; Abplanalp, 1983).

Drug-induced nystagmus is most commonly caused by alcohol, barbiturates, tranquilizers, phenothiazine, and anticonvulsant therapy. Spontaneous onset of nystagmus may indicate the presence of brainstem, cerebellar, or vestibular labyrinthine disease (Dell'osso, 1991; Adams, 1989). Any recent nystagmus should be evaluated by a neurologist and will not improve with vision therapy or biofeedback therapy.

Vision therapy has been used to treat nystagmus. Most studies of vision therapy to treat nystagmus have used biofeedback techniques. However, the development of biofeedback techniques was preceded by several reports on the use of vision therapy to treat nystagmus.

Healey (1952) provided case reports of 4 children with esotropia and congenital nystagmus. The children's nystagmus transiently disappeared when fusion occurred at the patient's deviation angle. The author found that nystagmus was reduced or eliminated after exercise and/or surgery to reduce esotropia in children. However, this is one of the only reports in the literature of resolution of nystagmus after correction of esotropia.

Stohler (1973) reports on the "afterimage treatment" of 6 patients aged 6 to 19 years with congenital nystagmus. Each patient sat in a dark room and a flashlight was turned on in front of the patient. After the flash, a light positioned behind the patient began to flicker to create both positive and negative afterimages. The patients worked to reduce the amplitude of the nystagmus by stabilizing the afterimages. These residual images essentially created a visual means of biofeedback and alerted the patient to her nystagmus. The patients practiced with the strobe light in practice for one hour a day on two consecutive days. The patients were then allowed to take the flash and practice at home every day for 2 months. At least minor improvements in visual acuity were noted in each patient after the two-month practice period. Two of the patients were able to reduce the frequency of the nystagmus movements, but in another 2 patients the frequency of the nystagmus movements was increased. Stoehler concluded that "it is not yet possible to draw many conclusions from the six patients we treated because our sample was too small and our follow-up was too short." Reviewing Stoehler's study, Stegall (1973) noted: "I would like to emphasize that the treatment presented in this article [by Stoehler] did not cure the nystagmus but only altered it, which would indicate that further study is needed."

The remaining studies on visual therapy for nystagmus have focused exclusively on the use of auditory biofeedback (Abdai et al., 1980; Ciuffreda et al., 1980; Goldrich et al., 1981; Ciuffreda et al., 1982; Kirschen, 1983; Ishikawa et al., 1985; Mezawa, 1990). In general, an auditory biofeedback device for nystagmus suppression consists of an infrared eye movement monitor that detects horizontal eye movements and, after appropriate calibration, records the horizontal position of the eye relative to the fixation target (Abplanalp , 1983; Kirschen, 1983). . Eye movement signals are collected by sensors and electronically converted into tones that indicate the direction and amplitude of the eye position error. The direction of the error is communicated to the patient by the ear in which the sound is heard: errors to the right are heard in the right ear, and errors to the left are heard in the left ear. Also, the sound quality in the two ears is different. The amplitude of the error is indicated to the patient by the frequency of the tone: low frequencies represent small errors in eye position and high frequencies represent large errors. A dead band, the width of which is controlled by the operator, is inserted coincident with the fixed target. The dead zone represents the angular distance that the patient can move their eyes without activating the acoustic feedback loop. For other protocols, the dead zone may produce a different tone, such as B. a series of soft clicks. The goal is to silence the audio tones for as long as possible or keep the clicks soft. Initially, the dead zone is large. As the patient gains control of his fixation nystagmus, the dead zone gradually reduces, forcing a more stable and precise fixation (Abplanalp, 1983; Kirschen, 1983).

Ciuffreda et al. (1982) investigated the use of auditory biofeedback on eye movements in the control of nystagmus. The horizontal position of the eyes was controlled by a photoelectric technique used in weekly training sessions (3 to 15 weeks) of 1 hour in 5 men aged 25 to 49 years. Patients had congenital twitch nystagmus (manifest or latent) or acquired pendulum nystagmus. They were asked to try to reduce the fluctuating sound quality that reflected changes in the horizontal position of the eyes. TV acuity was assessed before each session, without attempting to control nystagmus, and after each session with patients using the newly learned training strategies but without auditory biofeedback to reduce nystagmus and increase visual acuity, as suggested by Snellen- Letter and "Tumbling E". set graphics.

Total auditory biofeedback time received during therapy ranged from 53 to 342 minutes (Ciuffreda, 1982). All five patients were able to reduce their nystagmus within the first or second session and in one patient after only 15 minutes of training. As training progressed, the patients could reduce the amplitude and/or frequency of the nystagmus. The maximum group mean reductions in nystagmus amplitude, slow phase peak velocity, and rate with auditory biofeedback were 82, 86, and 34%, respectively. When the audio signal was suppressed periodically during training and testing, all patients were able to maintain their reduced nystagmus for several minutes. Additionally, subjects were able to reduce nystagmus at will without auditory biofeedback but with conscious effort while engaging in conversations and other tasks with the experimenters. The improvement in visual acuity following a subject's conscious effort to control nystagmus without the aid of biofeedback averaged 10% Snell Sterling (1 to 4 lines on a standard Snellen eye test chart). Of the 2 patients who returned for a post-exercise study several months later, 1 was able to reduce nystagmus to 50% of its pre-exercise level within a few seconds without the aid of biofeedback. Both subjects were able to reduce their nystagmus to the maximum values ​​reached during training with the help of a few seconds of auditory biofeedback. The authors concluded that auditory biofeedback should be considered in the treatment of nystagmus, either alone or in combination with orthoptic and/or surgical procedures.

Kirschen (1983) reported the use of auditory biofeedback in the control of congenital nystagmus in 5 patients. Horizontal eye movements were recorded by an infrared eye movement monitor. The eye movement signals were electronically converted into auditory tones that helped the patient control her abnormal eye movements. Less than 1 hour was required for all patients to learn to use auditory biofeedback. The results of 3 patients were presented.

Reductions in eye movement amplitude measured from eye movement monitor recordings ranged from 41 to 73%, but the frequency was not significantly reduced (Kirschen, 1983). In fact, the frequency of eye movements in one patient increased from 2.2 to 2.8 Hz. There was an increase in Snell-Sterling visual acuity from 48.4 to 56% in one patient. In another patient, contrast sensitivity was measured before and during biofeedback. At very low spatial frequencies (1 and 2 cycles/degree) contrast sensitivity was reduced during biofeedback, but at higher spatial frequencies (4 and 8 cycles/degree) sensitivity was increased. The reason for this discrepancy was not clear. Furthermore, 1 patient was able to control his nystagmus 1 year after his first training session in the laboratory. He was able to control his eye movements for 1 minute or more without the aid of auditory biofeedback. The author suggested that auditory biofeedback of eye position might be useful in treating congenital nystagmus.

Mezawa et al. (1990) studied the changes in the congenital nystagmus waveform associated with biofeedback therapy in 7 patients aged 7 to 20 years (3 women and 4 men). The 7 patients had congenital horizontal nystagmus: 4 of the jerk type and 3 of the pendulum or pseudopendular type. Each subject participated in auditory biofeedback for nystagmus suppression 5 to 6 times over a 6-month period. The right retina of each subject was viewed with an infrared television fundus camera and the fundus image was recorded on videotape. The eye position recorded with the fundus camera during nystagmus was analyzed at 1/60 second intervals. The change in degrees between the fixation target projected onto the retina and the foveola was measured for each interval.

Using auditory biofeedback, patients were able to suppress nystagmus at will and prolong foveation time (Mezawa, 1990). On average, intensity (amplitude x frequency) decreased by about 40% and foveation time (milliseconds) increased by about 190%. After completing the training program, all 7 patients reported a subjective improvement in their vision with suppression of their nystagmus. These investigators concluded that it is possible that biofeedback training reduced nystagmus and increased foveation time, thus improving fixation ability.

Ishikawa et al. (1985) also reported the use of biofeedback treatment in 30 patients with congenital twitch-type nystagmus. Patients received biofeedback regarding eye positions and tension in the muscles of the eyelids, neck, pharynx, shoulders, and diaphragm. After 1 year, the results were rated as excellent in 10 subjects; moderate at 12; poor at 6; no effect on 1; and 1 patient dropped out of the study.

While there is limited evidence that biofeedback can reduce the intensity and velocity of nystagmoid eye movements, conclusive evidence of its long-term efficacy is lacking. To make biofeedback an established method for the treatment of nystagmus, well-substantiated experimental studies with large sample sizes and long-term observations are required.

In summary, many studies suggest that biofeedback may be effective in the treatment of various visual disorders such as nystagmus, strabismus, amblyopia, myopia, and blepharospasm. However, almost all of these reports were internal publications, abstracts of conference proceedings, case studies, or uncontrolled studies with small sample sizes. Where robust experimental studies with control groups, randomization, blinding, and statistical analysis have been conducted, biofeedback has not been shown to be effective in the treatment of anterior visual disturbances. Due to the lack of objective data, the efficacy of biofeedback in the treatment of various visual disorders remains unclear. More research with a better experimental design is needed to determine the efficacy of biofeedback in treating vision problems and the long-term efficacy of any improvements.

oculomotor dysfunction

The term oculomotor dysfunction refers to difficulty in moving the eyes. Vision therapy has been used in patients with saccades and tracking problems.

Eye movements have long been a concern of optometrists due to their importance in reading. Eye movements include saccades and chases. Saccadic movements are eye movements that allow us to quickly redirect our gaze so that the point of interest stimulates the fovea (Scheiman and Wick, 1994). In reading, saccadic eye movements are made as the reader moves along a line of print.

Most of the symptoms associated with poor saccades are believed to be related to reading, such as: B. Head bobbing, frequent loss of space, word skipping, line skipping, slow reading speed, and poor comprehension ( Scheiman and Wick, 1994). A short attention span is also said to be related to problems with saccadic movements.

Chases involve eye tracking and allow us a continuous clear view of objects moving in space (Scheiman & Wick, 1994). Activities can be stimuli-generated or voluntary. Stimulus-generated chases are activated when a child is instructed to follow a moving target, while voluntary chases are activated when the child is instructed to follow a stationary path.

Although tracking difficulties have been reported in children with reading difficulties, tracking disorders are more likely to interfere with activities such as sports (Scheiman & Wick, 1994).

Press (1993) described tests used to diagnose ocular motility problems in a school-age child. Ocular motility tests deal with saccadic fixations and activities.

There are several tests to assess the saccadic ability of the child (Scheiman & Wick, 1994). These include objective eye movement recorders such as Visagraph and Eye-Trac, standardized tests such as the Developmental Eye Movement (DEM) test, and direct medical observations. Although eye movement recorders such as Visagraph and Eye-Trac provide objective and accurate measurements of eye movement, they are expensive, time consuming, and difficult to use with young children. The DEM and other tests that use a visual-verbal format assess oculomotor function based on the speed with which a series of numbers can be accurately seen, recognized, and verbalized; These tests are inexpensive, easy to perform, and provide a quantitative assessment of eye movement in a simulated reading environment. Physician assessment of the child's eye movements through direct observation is highly subjective and the results are difficult to quantify.

Methods have been developed to measure stimulus-elicited and voluntary tracking eye movements. The most common method of eliciting a stimulus-elicited chasing movement is to ask the child to follow a flashlight or a bright object (Scheiman & Wick, 1994). The movements are horizontal, vertical, diagonal, rotating, in and out (z axis). The examiner observes how closely the child follows the target.

A commonly used clinical test of voluntary motion tracking is Groffman Visual Tracings. This test, which requires the child to visually trace a path between a letter on one side of the sheet and a number on the opposite side of the sheet, requires a significant level of visual perception. However, one shortcoming of the Groffman Visual Tracings test is that no study has been done on its reliability and validity.

Press (1993) described vision therapy techniques used to improve oculomotor performance. This includes chase training and saccadic activities. Tracking training includes oculorotary exercises such as pie pan spins, in which the child follows the circular path of a marble that is tilted around the inner axis of a pie pan, and the Marsden ball, in which the child follows the vertical trajectory of a ball. thrown to the ball hangs from the ceiling. Another commonly used follow-training exercise is the vertical rotator, in which the child follows a visual target placed on a tripod that rotates clockwise or counterclockwise.

Saccadic activities are performed using the large Hart diagram (Press, 1993). The child begins wide-angle saccades by calling out the first and last letters of each line. The child then makes saccades with smaller angles by reading each letter aloud in turn.

Both the chases and the saccadic movements can be trained with activities that involve hand-eye coordination (Press, 1993). There are plenty of such activities, such as the Wayne Sakcadic fixer and the pegboard rotator. The Wayne Saccadic Fixator includes a central fixation point and a circular array of lights. The child is asked to touch the button next to each light that is on. The pegboard rotator involves a rotating tabletop with holes into which pegs are inserted. The child is instructed to visually align the pin over the hole and follow it one revolution before placing the pin in the hole.

Scheiman and Wick (1994) noted that vision therapy for eye movement skills in general involves more than just treatment techniques for saccades and tracking. As a general rule, binocular and accommodative vision techniques are included in the therapy program, since eye movement abnormalities are often associated with accommodative, binocular, or visual perception disorders.

Wold and colleagues (1978) reviewed the records of a series of 100 consecutive patients with learning disabilities who had undergone vision therapy for a variety of problems including malaccommodation, binocular dysfunction, and oculomotor dysfunction. Vision therapy consisted of three one-hour visits per week that continued for 22 to 53 weeks. Eye movements were rated on the Heinsen-Schrock scale, a 10-point ordinal scale for observing and rating saccadic eye movement tracking and performance. The researchers found that before therapy, only 6% of children had adequate saccadic and tracking function, whereas after vision therapy, 96% had adequate eye movement function. However, almost all patients had binocular and accommodative vision disorders in addition to eye movement disorders. Wold's study was an uncontrolled retrospective study of consecutive cases seen in private practice; The uncontrolled and retrospective nature of the study makes it fraught with significant biases. Possible sources of bias are maturation effects, test-retest bias, placebo effects, and regression to the mean. The author was able to report statistically significant results through the inappropriate use of statistical tests applied on ratio or interval scales to the 100-point visual function order scale that the author created. As Andersen explained, "parametric statistical tests [such as Student's t-test] that use means and standard deviations (ie, require arithmetic operations on the original results) should not be used with data on an ordinal scale." over 100 consecutive vision therapy cases with different types of binocular dysfunction reported without breakdown of cases by specific diagnosis. Therefore, we are uncertain about the effectiveness of these techniques in patients with a specific diagnosis of oculomotor dysfunction. Finally, there is no information on whether any of these learning disabled patients had vision-related symptoms or the impact of vision therapy on those symptoms.

Solan (1967) examined the results of vision therapy in 63 normal high school students. Subjects received twelve 2-hour group treatment sessions consisting of tachistoscope work, controlled reading, vocabulary, skimming and scanning, and study skills. Although the researchers noted increased reading speed, fewer fixations, and fewer regressions after treatment, the subjects received other forms of treatment in addition to vision therapy. This report does not provide information on the effectiveness of vision therapy in relieving symptoms associated with oculomotor dysfunction. The later work of Solan (1985a; 1985b) has been cited to support the efficacy of vision therapy for oculomotor disorders; these works report on a few selected cases, so no conclusions can be drawn about the efficacy of vision therapy in oculomotor dysfunction.

Rounds and colleagues (1991) studied eye movement reading before and after eye movement therapy in 12 adults with dyslexia and compared these results with those of 9 adults with dyslexia who received no intervention. Eye movement therapy consisted of 3 hours per week to improve oculomotor skills for 4 weeks. The researchers used a Visagraph to assess eye movement reading before and after therapy. Although the treatment group showed significant improvements in certain measures of eye movement compared to the untreated group, there were no statistically significant differences between the treated and untreated groups in reading efficiency and reading comprehension at the end of the study. The fact that measures of "eye movement efficiency" showed significant improvement without corresponding significant improvements in reading comprehension and reading efficiency also raises the question of whether eye movement efficiency is related to reading ability. Other problems with the study have to do with the fact that the control group received no treatment but a sham treatment. First, there was no blinding of subjects, observers, or therapists. Second, the lack of sham treatment raises the possibility that any differences between the two groups at the end of the study are due to the extra attention given to the treatment group. Third, this study examined improvements in reading efficiency through vision therapy; This study does not address the question of whether vision therapy is effective in relieving symptoms of oculomotor dysfunction.

Young (1982) evaluated the effects of vision therapy on 13 children from a learning center who had failed a vision test. There are no reports of any of these children reporting vision-related symptoms. Each child received three 5-minute vision therapy sessions per day, 4 days per week, for 6 weeks. The exercises were performed by a school teacher. Eye movements were recorded before and after Eye-Trac therapy. After therapy, the schoolchildren were found to have a significant decrease in the number and duration of fixations and an increase in their reading speed. Two major flaws in this study were the lack of a control group and the fact that the researchers measured eye movement efficiency rather than reading comprehension and reading efficiency. Furthermore, this study attempted to measure the effectiveness of vision therapy in improving reading ability, not in alleviating symptoms associated with oculomotor dysfunction.

Hung and colleagues (1986) measured various parameters prior to vision therapy in 21 symptomatic college students diagnosed with accommodation and/or vergence disorders and compared them to those measured in 22 visually normal, asymptomatic college students. The purpose of measuring visual parameters in asymptomatic subjects was to establish standards for the dynamic tests developed by the authors. Statistically significant differences were identified between symptomatic and asymptomatic subjects for a single variable: the slope of the open accommodation fixation gap curve. There was a statistically non-significant difference between symptomatic and asymptomatic subjects in the slope of the accommodative response to a stimulus. Symptomatic patients then received vision therapy and were reassessed upon completion of therapy. However, asymptomatic subjects were not retested at the end of the study and therefore were not a true control group.

The study by Hung and colleagues (1986) has several problems that make interpretation of the results difficult. First, because this study is uncontrolled, we don't know if the improvements in symptoms were due to vision therapy. Second, the variables that differed significantly between asymptomatic and symptomatic subjects were not those that changed significantly with orthoptic therapy. Third, symptom severity was measured on a scale of exponential order, and symptom reduction was considered "significant" if it fell by an arbitrary number of points; However, we cannot say whether this reduction in symptoms was clinically significant. Finally, although this study was cited as supporting the effectiveness of vision therapy for oculomotor dysfunction, the study only measured changes in accommodation and vergence with vision therapy.

Punnett and Steinhauer (1984) compared the results of eye movement vision therapy with and without feedback in 6 children, ages 9 to 12, who were diagnosed with oculomotor problems and who were reading well below grade level. Four of the children were assigned to vision therapy with reinforcement and 2 were assigned to a control group that received no sham treatment. Children's eye tracking, reading comprehension, accuracy, and reading level were measured before and after treatment. Although reading comprehension and reading levels appeared to increase more in children receiving vision therapy, statistical analysis could not be performed due to the small number of subjects in each group. The study did not specify whether the children were randomly assigned to the groups, and children in the control group did not receive placebo or sham treatment. The study examined the efficacy of vision therapy in improving the reading skills of learning disabled children with oculomotor dysfunction, but did not examine the efficacy of vision therapy in relieving symptoms associated with oculomotor dysfunction.

Busby (1985) studied the efficacy of vision therapy in improving eye movement control, hand-eye coordination, and pattern-copying and imagery skills in 59 special education students ages 7 to 10 with neurological and speech difficulties. The students received 30-minute group vision therapy sessions twice a week for 9 months. Visual therapy was performed by teachers in the classroom. Students generally improved on each of the tests after vision therapy. But reading and teaching performance after one year was only measured qualitatively. The students also attended other courses during this time, so it is not known how much of the improvement on these tests can be attributed to vision therapy. There was no control group, so it is not known if the improvements could be due to ripening effects. Finally, the study examined the effectiveness of vision therapy in controlling eye movement, hand-eye tasks, and visuomotor skills rather than oculomotor dysfunction symptoms.

Heath and colleagues (1976) studied the efficacy of oculomotor and convergence exercises in 80 second- and third-grade children who had scored below the 40th percentile on a reading test and in the poor range on an oculomotor follow-up exam. . Subjects were randomly assigned to 4 groups: group 1 received oculomotor and convergence exercises with proprioceptive (touch) reinforcement; group 2 received exercises without reinforcement; group 3 received sensitization exercises (sham treatment); and Group 4 received no treatment. 17 of the 80 subjects dropped out before the end of the study; however, an intention-to-treat analysis was not performed. Subjects were treated over a 12-week period; the frequency of vision therapy visits was not specified. Group 1 (proprioceptive exercise) showed significantly greater improvements in measures of aspiration and convergence than the other groups, including Group 2, which received only vision therapy exercises. On tests of reading and eye tracking, Group 1 performed significantly better than the group that received no treatment (Group 4); Differences in reading improvement between Group 1 and Groups 2 and 3 were not statistically significant. The study did not determine whether the group that received vision therapy alone (Group 2) performed statistically significantly better than the group that received sham treatment (Group 3) and the group that received no treatment (Group 4) on each one of these variables). It is unclear whether the improvements in Group 1 were the result of convergence exercises or exercises to improve oculomotor function. Finally, this study examined the effectiveness of vision therapy in improving reading-related skills, rather than the effectiveness of vision therapy to alleviate symptoms associated with oculomotor dysfunction. .

Two studies by Schroeder and Holland (1968; 1969) have been cited in support of the efficacy of biofeedback in improving motor function of the eye. Both uncontrolled studies involve normal university volunteers, 3 in 1 study and 6 in the other. None of these students had oculomotor dysfunction. Therefore, no conclusions can be drawn from these studies about the effectiveness of vision therapy in patients with oculomotor dysfunction.

Biofeedback has been used by other investigators to improve oculomotor skills in patients with nystagmus and eccentric fixation, which is discussed in separate sections below.

The literature on the efficacy of vision therapy for ocular motor disorders is largely characterized by anecdotes, case reports, or uncontrolled studies with small numbers of cases. These case series cannot determine whether there was bias due to maturational effects, retest and retest effects, and non-specific gains that accrued simply from paying more attention to the child (Levine, 1984). . Interpretation of these case series is also hampered by the relative lack of knowledge about the natural history of untreated visual impairment.

In a review of the literature on vision therapy for reading problems, Beauchamp (1986) found that oculomotor search or "tracking" deficiencies are claimed. However, there is evidence that these "deficits" disappear when the content is corrected for reading level and "the oculomotor control of dyslexic children is similar to that of normal children" (Black, 1984). Reports demonstrating abnormal seeking in samples of children with dyslexia do not provide unbiased sample measures of abnormal seeking problems in the general population for comparison (Sherman, 1973).

Most controlled trials on the efficacy of vision therapy have not used random assignment, and the comparison groups used in non-randomized trials have not been carefully matched for factors influencing therapy outcome. These studies also often lack therapist-observer blinding, independent statistical design, and independent analysis and evaluation of effects. Some do not provide a statistical analysis of the data and many do not control for confounding variables. Control subjects in several studies received no dummy or placebo treatments. The studies also present their results as averages and do not provide subgroup or group analyzes to identify the characteristics of patients who are more likely to respond to vision therapy. Furthermore, many of the studies reported high dropout rates and these studies did not use intention-to-treat analysis of the results.

The lack of standardization of vision therapy techniques and methods, as well as differences in the frequency and duration of vision therapy, make it difficult to make generalizations about the effectiveness of vision therapy from the results of a single study (Beauchamp, 1986).

According to Keogh, there is also "inconsistency and confusion in the types of samples used" in studies of vision therapy (Keogh, 1985), which limits the conclusions that can be drawn from research on vision therapy for children with reading difficulties. Furthermore, investigators often fail to identify and quantify visual disturbances in treated patients (Beauchamp, 1986).

Many vision therapy regimens incorporate non-optometric interventions such as general body movement, exercise, diet, and most importantly, standard healing education techniques. Studies of such vision regimens are difficult to interpret, as the efficacy of these regimens may be more likely due to non-optometric interventions, such as standard remedial education techniques, rather than vision therapy itself. Furthermore, these other elements may be better provided by non-ophthalmic professionals such as opticians. B. healing teachers. Beauchamp notes that "one may legitimately question an optometrist's ability to work on such complex issues" outside of optometry (Beauchamp, 1986).

There is also a lack of information on whether the results achieved with vision therapy are permanent (ie persist over time) or if the effects of the therapy are transient and short-lived.

Beauchamp (1986) concluded that it is not enough to speculatively recommend an intervention such as optometric vision therapy for dyslexia because "time and financial resources are finite". "It is not unlikely that focusing efforts on educational methods will provide a more direct and cost-effective intervention" (Beauchamp, 1986).

The AAO, the American Association for Pediatric Ophthalmology and Strabismus, and the AAP (March 1992) concluded that vision therapy is not an effective treatment for reading problems and other learning disabilities.

The AOA concluded that the most common oculomotor dysfunction requires up to 18 hours of vision therapy. However, the AOA has not presented any evidence or justification for this conclusion. As the above review shows, most clinical trials of vision therapy for oculomotor dysfunction have used much less than 18 hours of office therapy.

Most studies of vision therapy for oculomotor dysfunction have focused on exercise at home. Optometric orthoptic therapy has focused on in-office therapy, while orthopedic orthoptic therapy has focused on home exercise. However, there is no evidence that office orthotics are superior to home exercise. Therefore, patients receiving treatment for oculomotor dysfunction can switch to a regimen that emphasizes exercise at home.

traumatic brain injury

The visual system may also be affected in patients with TBI. The most common visual problems associated with TBI are binocular dysfunction, blurred vision, ocular motility deficits, visual field loss, and visual motor perception deficits. These visual disturbances may be related to damage to the cranial nerves, particularly the III (oculomotor), IV (trochlear), and VI (abducens) nerves. It should be noted that patients with TBI may perform poorly in visually mediated activities as a result of attention and problem-solving deficits, poor manual dexterity, or ataxia rather than visuospatial deficits per se. There is currently a paucity of research linking visual perception deficits with dysfunctional performance of activities of daily living.

Most rehabilitation efforts focus on patients with severe TBI (loss of consciousness for 6 hours or more). In the early stages of rehabilitation, inpatient services include physical, occupational, and speech therapy and emphasize the development of cognitive skills, compensatory techniques, emotional adjustment, physical fitness, and health maintenance. In the later stages of rehabilitation, when a patient has returned home but continues to have physical or neurobehavioral problems, an outpatient program may be recommended. Currently, vision therapy is not an integral part of inpatient and outpatient rehabilitation programs for patients with TBI.

Some optometrists have advocated for optometric therapy to play a role in the treatment of patients with traumatic brain injury. However, there are limited data on the use of vision therapy and its benefits in TBI patients. In a case study, Aksionoff and Falk (1992) reported that optometric therapy helped a 70-year-old man suffering from a left-hemisphere stroke. After 1 year of weekly 45-minute sessions, the patient showed improved cognition and spatial relationships: he no longer complained of bumping into objects and was able to use the phone successfully again. Cohen (1992) described the optometric treatment of binocular dysfunction in 2 patients. The first patient was a 25-year-old man who sustained a closed frontal head injury when his bicycle was struck by a truck. He had exotropia, poor convergence, and difficulties with motor planning. After 30 vision therapy sessions, he was able to read more accurately and comfortably, but still had significant difficulties with order and writing. The second patient was a 20-year-old man who sustained a closed head injury in a car accident. He had esotropia as a result of 6th cranial nerve palsy. After 50 sessions of therapy in the office, his visual acuity was 20/20 (compared to 20/50 before therapy) and his field of vision was full in almost all directions, with a slight limitation that was evident. when looking to the right. .

In a retrospective study, Gianutsos et al. (1988) The effects of optometric rehabilitation services in a group of TBI patients. The visual function of a total of 55 patients was evaluated and it was found that more than 50% required treatment. Twenty-six patients were referred to a rehabilitative optometrist specializing in low vision. It was reported that 24/26 patients receiving therapy had an improved functional outcome. Unfortunately, the details of the outcome, as well as the improvement, were not disclosed in this study. As in the case reports described above, this study did not have a control group, making it difficult to determine whether the observed improvements in visual function were due to optometric therapy or other therapies in the rehabilitation program and/or spontaneous recovery. More importantly, the relevance of vision therapy for functional performance, particularly in activities of daily living, must be demonstrated through clinical research before this type of therapy can be considered an integral part of a vision rehabilitation program. TBI.

There are few data documenting the use of vision therapy to treat visual impairment in patients with TBI. More research is needed, particularly studies demonstrating the long-term benefits of vision therapy (its impact on activities of daily living and its impact, if any, on other areas of rehabilitation) before it is considered a part Comprehensive traumatic brain injury. rehabilitation program.

Traumatic brain injury and concussion

The American Medical Society for Sports Medicine statement on "Concussion in Sports" (Harmon et al., 2013) and the Ontario Neurotrauma Foundation Guidelines for the Diagnosis and Treatment of Pediatric Concussion (2014) do not mention the vision therapy as a management tool.

Also, UpToDate reviews on "Concussion and Mild Traumatic Brain Injury" (Evans, 2016a), "Post-Concussion Syndrome" (Evans, 2016b), and "Children and Adolescent Concussion: Management" (Meehan and O'Brien, 2016) do not mention vision therapy as a management tool.

Traumatic Brain Injury and Neurovision Technology

Rasmussen and colleagues (2018) found that 30-35% of people experience severe and often persistent visual impairment after stroke. Vision may be considered the most important human sense, and even minor permanent injuries can drastically reduce quality of life (QOL). Recovery from visual field defects occurs only to a small extent during the first month after brain injury, and therefore the window for spontaneous improvement is limited. Within a month after visually impaired brain injury, patients are often chronically visually impaired and the need for compensatory visual rehabilitation is significant. The aim of this study is to investigate whether rehabilitation with Neuro Vision Technology leads to a significant and lasting improvement in functional performance in people with chronic visual impairment after brain injury. Vision improvement is expected to improve both physical and mental functioning and thus improve QoL. This is an open-label prospective study evaluating participants with chronic visual field defects before and after the procedure. Participants typically suffer from a stroke or traumatic brain injury and are recruited from hospitals and the Institute for the Blind and Visually Impaired. Treatment is based on Neuro Vision Technology, a supervised training course where participants are trained in compensatory techniques using specially designed equipment. Through the Neuro Vision Technology process, each individual's vision problems are carefully examined and personal data is used to organize individual training sessions. There will also be face-to-face cognitive assessments and self-assessment questionnaires on quality of life and quality of vision before and after the training. Financing took place in June 2017; Results are expected in 2020. The sample size is calculated for 23 participants. Due to age, transport difficulties and time-consuming intervention, up to 25% demolition can be expected; therefore, these investigators aim to include at least 29 participants. The authors concluded that this study will evaluate the effects of Neuro Vision Technology therapy in the rehabilitation of compensatory vision. In addition, cognitive and quality of life improvements associated with increased quality of life will be examined.

Vertical deviations

Vertical deviations refer to unconjugated eye movements in the vertical plane (up and down). They are a rare type of strabismus (squinting). Vision therapy was used to correct the vertical deviations.

Hyperphoria or hypertropia occurs when one line of vision is higher than the other. It is present on the right when the right line of sight is higher than the left, and on the left when the left line of sight is on the right. Hypertropia is also known as vertical squint.

Symptoms of vertical deviation include asthenopic symptoms (headache, fatigue, drowsiness, blurred vision), loss of reading space, dizziness, nausea, and motion sickness (Cooper (1988) citing Amos (1987) and Scobee (1950)). Large vertical deviations can result in loss of binocular vision, cosmetically disturbing hypertropia, and overt diplopia. With vertical deviations due to paralysis of the upper oblique muscles, compensatory torticollis, turning the face or tilting the head to the opposite shoulder, is common. Chronic torticollis can lead to asymmetrical facial development and postural plagiocephaly ("banana face" deformity).

Von Noorden (1996) quoted Adler (Moses, 1970) when he reported that hyperphoria of 1 prism diopter in both eyes produced symptoms; therefore, only a hyperphoria of 0.5 prism diopters can be considered within the physiologic range. These levels are clinically significant and require treatment, but only if they cause symptoms. However, von Noorden noted that the clinical significance of vertical deviations and other heterotropies depends less on their absolute values ​​than on correlated findings, such as fusion amplitudes.

Caloroso and Rouse (1993) found that 2 characteristics of the abnormality, extension and frequency, are the main factors that determine which patients undergo surgery. As a general guide, they stated that if the patient's smallest deviation, measured with best correction, is greater than 10 prism diopters for vertical tropia, surgery will be necessary to reduce or eliminate the vertical deviation so that the patient can align comfortably. both eyes in open spaces.

With respect to vertical deviations and aesthetics, Flom (1958) found that vertical squint is generally imperceptible to a lay person when he has less than 10 prismatic diopters of vertical hypertropia.

Evidence on the effectiveness of orthoptic treatment for vertical deviation is scant and conflicting. Based on his clinical experience, Layland (1971) concluded that hypertropia is unlikely to respond to orthoptic treatment. Mann (1947) commented on his experience and concluded that paralytic forms of vertical deviation never respond to orthoptic treatment, but orthoptic treatment may help some patients with non-paralytic vertical deviation.

The AOA position paper on vision therapy for strabismus mentions only use in esotropia and exotropia (American Optometric Association, undated). There is no statement on the effectiveness of vertical deflections. In addition, the AOA Clinical Guidelines on Strabismus mention the use of vision therapy only for esotropia and exotropia (AOA, 1995).

There are few published clinical studies on the effectiveness of orthoptics on vertical deviation. Six studies were identified; All of these studies combined reported orthoptic outcomes in fewer than 70 patients. Of these, 2 were selected case reports. Three of the studies included only 3 patients each, 1 study included 10 patients with vertical deviations, 1 study included 13 patients with vertical deviations, and 1 study included 37 patients with vertical deviations. All of these studies included a retrospective review of optometric records. None of these studies used control or comparison groups. And none of these studies provided a statistical analysis of the results.

The two largest studies (Ettinger, 1978; Ludlam, 1960) excluded dropouts from the analysis and Ludlam also excluded patients who were still completing treatment from the analysis. All patients with vertical deviations in the 3 largest studies had associated esotropia or exotropia; therefore, we have almost no information on the effectiveness of orthoptics in patients with isolated vertical deviations. Zaki (1972) and Etting (1978) found lower functional cure rates in patients with strabismus than in patients with strabismus without vertical deviations. However, Ludlam (1960) found that cure rates for horizontal strabismus were the same regardless of the presence of associated vertical deviation.

Few small studies have reported the effectiveness of orthoptic treatment for vertical deviation. Cooper (1988) described 4 patients with large vertical deviations, 3 patients with intermittent hypertropia, and 1 patient with alternating hyperesotropia (range of deviation 6 to 12 diopters of vertical tropia), who were treated with a combination of prismatic and ortho-optic spectacles. The treatments resulted in relief of symptoms and a reduction in the need to use vertical prisms, although fusion areas improved in only 1 of 4 subjects.

Robertson and Kuhn (1985) used orthoptics to treat 3 hyperphoric patients (range of deviation 1.5 to 4 diopters of vertical phoria). All 3 reported symptom relief. However, although the orthoptic exercises emphasized vertical fusion range expansion, only one subject's vertical fusion ranges were significantly improved. Finally, no conclusions can be drawn from these selected case reports on the effectiveness of orthoptic treatment of patients with height deviations.

Zaki (1972) reported the results of orthoptic treatment of 120 children aged 5 to 7 years with less than 12 degrees of strabismus, including 10 children with hypertropia, 6 with concomitant exotropia, and 4 with concomitant esotropia. Children received orthoptics twice weekly for a total of 12 weeks (24 visits). The investigator reported a successful outcome in only 2 of the 10 patients (angle is between 0 and 5 degrees with and without spectacles, with good fusion, binocularity, and stereoscopic acuity). The rest of the patients required surgery.

Hoffman et al. (1970) reviewed the results of orthoptics in 55 consecutive strabismus observed in a private optometry clinic over 2 years. Only 3 of the cases had vertical deviation (in all 3 cases the vertical deviation was associated with esotropia) and their results with orthoptic treatment were not reported separately.

One of the largest studies on the effectiveness of orthoptics in patients with vertical deviation was carried out by Etting (1978) who analyzed the optometric records of 86 patients aged 6 to 40 years with strabismus who had orthoptics, including 13 patients with vertical deviation. had associated exotropia. Subjects excluded if the strabismus appeared before the age of 6 years or if they dropped out before the completion of 24 visits were also excluded from the study. The investigators measured both functional cure rates and cosmetic cure rates. Functional cure included comfortable clear vision, normal near point of convergence, normal stereopsis, and fusion areas. Cosmetic healing was defined as a final deviation angle of 15 prism diopters or less, or if there was less deviation at baseline, improvement of abnormal fusion.

Of 13 subjects with vertical deviations and exotropia, 6 (46.1%) were functionally healed after vision therapy and another 5 (38.4%) achieved cosmetic healing (Etting, 1978). This compares with a functional cure rate of 70.9% and a cosmetic cure rate of an additional 19.7% in the total sample. Five subjects with vertical deviations had prior surgery; 2 of these patients (40%) achieved functional healing and another 2 patients (40%) achieved cosmetic healing. Six subjects with vertical deviations also had amblyopia; only 2 of these 6 subjects (33%) achieved a functional cure and another 2 subjects (33%) were cosmetically healed.

The presence of normal retinal correlation was an important factor in functional healing: 6 of 8 subjects (75%) with vertical phoria and normal retinal correlation achieved functional healing with orthoptics, and an additional 1 subject (12.5%) achieved healing. aesthetics (Etting, 1978). ). But none of the 5 subjects with vertical phoria and abnormal retinal correspondence achieved functional cure; 4 (80%) achieved cosmetic healing. Therapy was offered in the office for half an hour, twice a week. In addition, up to half an hour of home therapy was assigned. On average, 48 office therapy sessions were used to treat patients with vertical deviation.

Ludlam (1961) reviewed the medical records of 517 patients treated in an orthoptic clinic over a 4-year period, of whom 284 had strabismus. Patients who were still in training (n=51), dropped out before completing 8 orthopedic training courses (n=48), had paralytic strabismus (n=8), had a deviation that could be corrected only with glasses (i.e., accommodative esotropia ) were excluded) (n = 9) or if they had been operated on previously (n = 19). The results of the remaining 149 cases have been reported. Of the 149 patients with strabismus, 37 had hypertropia (range 2 to 22 prism diopters), of which 17 were associated with esotropia (hypersotropia) and 20 with exotropia (hyperexotropia). Patients received office orthoptic training once or twice a week, supplemented by home exercise in almost all cases. Functional cures were those who had clear and comfortable binocular vision, normal near point of convergence, stereopsis, and normal ranges of motor fusion. The "almost clear" category included includes patients who fit the "functionally cured" category, except that they do not have stereopsis, may present with diplopia squint up to 5% of the time, and/or may require significant amounts of prism for binocular viewing. . keep vision. Of the 17 patients with hyperesotropia, 4 (23.5%) achieved functional cure with orthoptics and 10 (58.8%) were almost cured. Of the 20 patients with hyperexotropia, 8 (40%) were functionally cured and 7 (35%) were nearly cured. This compares to a 46.5% functional cure rate for exotropia and a 26.6% functional cure rate for esotropia. Therefore, the presence of a vertical component did not appear to affect the cure rates of esotropia and exotropia. Ludlam noted that this finding contradicts previous reports that vertical deviation was a major barrier to functional healing with orthoptics. In patients who achieved functional cure, the average number of practice sessions was 23 for exotropia and 32 for esotropia.

In a later study, Ludlam (1965) reported the long-term results of orthoptic treatment of strabismus. In 1963, the investigator reexamined 82 patients from the earlier study who were considered at least moderately cured at the time of their discharge from vision training between 1956 and 1960. Of 12 patients with hyperesotropia who returned for reassessment in 1963, 5 they had improved since they finished the training, 5 remained unchanged and 2 worsened. Of 14 patients with hyperexotropia who returned, 6 improved since discharge from training, 9 remained unchanged, and 2 worsened.

There was a wide variation in the number of doctor visits needed to treat the vertical deviation. Zaki (1972) and Ludlam (1960) reported a mean treatment duration of 32 visits or less, while Etting (1978) reported a mean treatment duration of 48 visits. Despite the increased number of office visits, Etting's success rates were lower than Ludlam's.

In contrast to isolated reports of the effectiveness of orthoptics for height deviations, the results of larger prospective case series on surgery for height deviations have been published. Saunders (1995) reports that surgical strengthening of the oblique muscles, often performed in combination with surgery of other extraocular muscles, is effective in concomitant hypertrophy due to superior oblique muscle palsy. However, it is not known whether early strabismus surgery can prevent or reverse postural plagiocephaly from chronic torticollis.

Saunders (1995) states that patients with small vertical deviations of less than 10 prism diopters and no symptoms of torsion can sometimes be successfully treated with prism spectacles. If surgery is necessary, superior oblique tendon lift is appropriate as the primary procedure in patients with less than 10 prism diopters of hypertropia in primary gaze position.

Successful results (elimination of torticollis and hypertrophy in and around the primary position) can be as high as 90% in selected populations (Saunders (1995), citing Toosi (1979) and Saunders (1986)).

Most patients who undergo a superior oblique tendon lift for indications do not require a second operation (Saunders, 1995). Davis and Biglan (1995) state that patients with diplopia and a vertical deviation greater than 5 prism diopters require reoperation for vertical deviation. Other indications for reoperation are residual head postures or tilts. If the amount of remaining or new torticollis exceeds 10 to 15 prism diopters, it is sufficient to consider additional surgery.

Vertical deviations may occur as a new finding after horizontal strabismus surgery, or they may occur as a result of under- or over-correction of previous hypertropia (Davis, 1995). Vertical deviations may also occur de novo as part of the natural history of a strabismus condition, such as B. A dissociated vertical deviation after horizontal correction of infantile esotropia.

Helveston (1979) found that for strabismus in general, a patient requiring reoperation has a 30% chance of needing another operation to achieve a satisfactory result.

Sprague (1995) reported that suturing may be an alternative in the treatment of patients with dissociated vertical deviation (spontaneous superduction of one eye when the patient is tired or daydreaming). But Esswein et al. (1992) retrospectively compared upper rectal suture surgery with major upper rectal recessions for dissociated vertical deviation and found better results with recession alone.

Buckley (1995) noted that there is little information on the efficacy of botulinum toxin injections in the treatment of vertical strabismus and that botulinum toxin may be contraindicated in some cases.

Although a comprehensive review of studies on the effectiveness of vertical shift surgery is beyond the scope of this review, one of the first studies on the effectiveness of vertical shift surgery is described below.

Lyle and Foley (1957) reported the results of surgical procedures with and without orthoptics in 107 patients with congenital paralytic strabismus; Of the 107 patients, 92 had binocular vision before the operation and 15 did not. The study outcome included freedom from symptoms and restoration of single binocular vision, including equal visual acuity, normal retinal correspondence, fusion, and stereopsis. Of the 15 patients without binocular vision, 3 had paralysis of horizontally acting extraocular muscles, 7 had paralysis of vertically acting muscles with secondary esotropia, and 5 had paralysis of vertically acting muscles with secondary exotropia. In no case was orthoptic treatment performed; The treatment consisted solely of an operation to improve the cosmetic appearance.

Of the 92 patients with congenital paralytic strabismus with binocular vision, 76 had vertical deviation (Lyle and Foley, 1957). Of the 76 with vertical deviation, 13 had an associated horizontal deviation and 63 did not. Of the 63 patients with isolated vertical deviation, 55 complained of symptoms before the operation. Fifty-one of the 55 symptomatic patients had complete relief and the other 4 partial relief of symptoms after surgery. Of the 8 patients with isolated vertical abnormalities who did not have symptoms, 7 had simple binocular vision after surgery and 1 required reoperation.

Of the 13 patients with a vertical deviation associated with a horizontal deviation, 9 had associated exotropia (Lyle and Foley, 1957). Eight of these 9 patients complained of symptoms before the operation; Six of these symptomatic patients (75%) had no symptoms after surgery and the other 2 symptomatic patients improved significantly. One of 9 children with vertical deviation associated with exotropia was asymptomatic before operation but had a compensatory head position. After the operation, the boy had binocular vision and his head position was normal.

Four patients had vertical deviation associated with esotropia (Lyle and Foley, 1957). Two of these patients were symptomatic before surgery. Both symptomatic patients also had a compensatory head position. Symptoms in one patient were relieved and head posture was normal after surgery. In the other patient, simple binocular vision was restored after surgery, but head posture remained abnormal. Two asymptomatic children with vertical deviations and esotropia also had compensatory head posture; After the operation, both had binocular vision and normal head posture.

Lyle and Foley (1957) also reported the results of surgery with and without orthoptics in 287 children under 10 years of age with nonparalytic esotropia, 213 of whom were nonaccommodative (ie, not correctable with spectacles). Fifty of the 213 children (24%) with nonaccommodative esotropia also had vertical deviation. Eight of 48 children (16.6%) treated with surgery alone achieved simple binocular vision, and 16 of 138 children (11.6%) treated with surgery and orthoptics achieved simple binocular vision See. But none of the 27 children treated with only orthoptics achieved simple binocular vision. Although a detailed analysis was not presented, the investigators concluded that the prognosis is not worse in patients with esotropia and vertical deviation, provided the vertical deviation is corrected by surgery. Lyle and Foley (1957) also reviewed the results of 121 children and adults with nonparalytic exotropia. The authors did not discuss the impact of associated vertical deviations on the outcomes in these patients.

heteroforia vertical

Vertical heterophoria (VH) is a form of binocular vision disorder (BVD) that results from a vertical misalignment of the eyes. It occurs when one eye is slightly misaligned and symptoms can include asthenopia, diplopia, dizziness, eye pain/tension, headaches including migraines, motion sickness, nausea, photophobia, sensory overload, and spatial disorientation. Treatment of OAB consists of correcting the misalignment with therapeutic prism glasses. There is a lack of published controlled clinical trials on the effectiveness of orthoptic vision therapy for the treatment of AH.

Assessment of visual information processing

Visual processing is a group of skills used to interpret and understand visual information. Visual Information Processing Assessment (VIPE) identifies problems in processing information to enhance academic and/or social development. Assessment may include tests of visuospatial orientation skills, visual analysis skills including auditory-visual integration, visuomotor integration skills, and rapid naming skills.

Goldstand et al. (2005) compared visual and visual information processing skills between children with and without mild reading and academic difficulties and examined their incidence of visual deficits. A total of 71 seventh grade students, classified as proficient (n = 46) and unskilled (n = 25) readers, were compared on scores on a recognized vision test, visual cognition tests, visuomotor integration tests, and academic performance. In addition, academic performance and visual information processing were compared between children who failed and passed the vision test. Vision problems were found in 68% of the participants, with significantly more boys than girls. Illiterate people had significantly worse school performance and vision exams than literate people. Participants who passed the visual test performed significantly better on visual perception than those who failed. The authors concluded that visual function differed significantly between children with and without mild school problems, as well as in terms of visual cognition scores. The high incidence of visual deficiencies among the participants justifies the inclusion of visual deficiencies in schoolchildren with academic difficulties. In addition, these researchers noted that "because the participants represent a convenient sample of seventh graders from a single middle school, caution should be exercised when generalizing the study results." This type of subject selection, combined with the relatively limited number of participants, means that the results obtained are not necessarily representative of the entire population. A larger sample, where participants are selected using random sampling techniques, would increase the ability of the investigators to extrapolate from results that increase the possibility of making type I or II errors when using t-test analyzes in group comparisons, the results of our study should be interpreted with caution." In summary, there is currently insufficient evidence to support the use of visual information processing assessments to aid in the diagnosis of reading or learning problems Well-designed studies with larger sample sizes are needed to establish the diagnostic utility of this technique.

Other indications

Optometrists have used vision therapy techniques to improve athletic performance in normal individuals. These include the use of binocular strings (Brock String), reverse card exercises, ball on a string (Marsden Ball), tachistoscopic exercises, eye-hand and eye-body coordination exercises, and the use of complicators (Kirscher, 1993). .

Vision therapy to enhance athletic performance is not considered medically necessary as, in this context, it is not intended to diagnose, prevent, or treat any disease or medical condition, but rather to enhance the performance of normal individuals.

The term "vision therapy" or "vision training" encompasses various practices related to the manipulation of the eyes with optical aids and eye movements, often in conjunction with proprioceptive exercises, biofeedback, cognitive style modeling, nutritional counseling, about family systems, psychology, and reading tutorials. As one authority explained, "the necessary and sufficient components of optometric vision training have not been specified (the practices are remarkably diverse), which precludes scientific evaluation of these practices" (Beauchamp, 1994).

Furthermore, there is no reason to believe that vision training would be an effective treatment for learning difficulties. This is because studies have shown no difference in ocular function between children with and without learning disabilities, and because there is no evidence that ocular dysfunction causes learning difficulties (Beauchamp, 1994).

Discussing the role of the eyes and vision in learning disabilities, Beauchamp concluded that "[t]here is a consensus that refractive errors, strabismus, and other eye disorders are not associated with academic functioning."

Specifically, regarding problems with visual tracking, studies have not found an increased incidence of tracking or movement disorders or other ocular motility abnormalities in children with learning disabilities. Carefully controlled studies have shown that "there is no increased incidence of ocular, optic, or ocular peripheral motility abnormalities" in children with learning disabilities (Beauchamp, 1994).

Visual deficits in children with learning disabilities are symptoms of a pervasive disorder and are not the cause of the learning difficulties. As Beauchamp explained, "[t]he group of individuals in whom a learning disability is accompanied by perceptual deficits related to visual input are more likely to present a symptom of a pervasive process than a primary or causal deficit" (Beauchamp, 1994).

In addition, the question arises as to whether optometrists are adequately trained to provide the non-ophthalmic elements of vision training, since "the ability of optometrists to work independently on such complex issues has been called into question" (Beauchamp, 1994). .

Beauchamp concluded that "in the absence of evidence of effectiveness [of vision therapy], the ophthalmologist is likely to recommend that the child's and family's resources (time and money) be directed to efforts most likely to produce positive results." ".

The main reason many children have been prescribed vision therapy is to treat reading problems (dyslexia) and learning problems by improving vision. However, there are no adequate studies to support the claim that visual, perceptual, or gross motor exercises help the weak reader. Helveston and colleagues (1985) found that there are no demonstrable relationships between academic performance and visual functioning. Other population-based studies have failed to find differences in visual function between normal and learning disabled individuals (Beauchamp, 1994). Therefore, there is little reason to train the vision of dyslexics and other people with learning disabilities.

Another problem in the vision training literature is the tendency to interpret findings narrowly, so that, for example, difficulty maintaining concentration during reading may be seen as a symptom of lack of visual efficiency rather than of a broader manifestation of attention deficit disorder in all modalities. Levin, 1984).

Furthermore, the vision therapy literature focuses on a single aspect of vision, eg, oculomotor tracking, and interprets an association or relationship as a problem, eg. B. Dyslexia as having causal implications. However, the evidence for such a causal relationship between visual performance and reading problems is "less convincing" (Beauchamp, 1986). In a review of vision training, Keogh and Pelland (1985) stated that "[i]n where visual impairment is not the cause of reading problems, vision training is not the treatment of choice..."

Beauchamp (1986) concluded that it is not enough to speculatively recommend an intervention such as optometric vision therapy for dyslexia because "time and financial resources are finite". direct and economic intervention" (Beauchamp, 1986).

The AAO, the American Association for Pediatric Ophthalmology and Strabismus, and the AAP (2009) issued a joint statement concluding that vision therapy is not an effective treatment for dyslexia or learning disabilities.

The above policy is based on the following references: