Vision therapy

Vision therapy, also known as vision training, is used to improve vision skills such as eye movement control and eye coordination. It involves a series of procedures carried out in both home and office settings, usually under professional supervision by an orthoptist or optometrist.^[1]

Vision therapy can be prescribed when a comprehensive eye examination indicates that it is an appropriate treatment option for the patient. The specific program of therapy is based on the results of standardized tests, the needs of the patient, and the patient's signs and symptoms. Programs typically involve eye exercises and the use of lenses, prisms, filters, occluders, specialized instruments, and / or computer programs. The course of therapy may last weeks to several years, with intermittent monitoring by the eye doctor.^[2][3]

Scope

Vision Therapy encompasses a wide variety of non-surgical methods^[4] which may be divided into several broad categories:

• Orthoptic Vision Therapy, also known as orthoptics.

Orthoptics is a field pertaining to the evaluation and treatment of patients with disorders of the visual system with an emphasis on binocular vision and eye movements.^[5] Commonly practiced by orthoptists, optometrists, behavioral optometrists, pediatric ophthalmologists, and general ophthalmologists, traditional orthoptics addresses problems of eye strain, visually induced headaches, strabismus, diplopia and visual related skills required for reading.

• Behavioral Vision Therapy, or Visual Integration Vision Therapy (also known as behavioral optometry).^[6]

Orthoptic visual therapy

Orthoptics aims to treat binocular vision disorders such as strabismus, and diplopia. Key factors involved include: Eye Movement Control, Simultaneous Focus at Far, Sustaining Focus at Far, Simultaneous Focus at Near, Sustaining Focus at Near, Simultaneous Alignment at Far, Sustaining Alignment at Far, Simultaneous Alignment at Near, Sustaining Alignment at Near, Central Vision (Visual Acuity) and Depth Awareness.^[7]

Some of the exercises used are:

• Near point of convergence exercises (i.e. "pencil push-ups"),
• Base-out prism reading, stereogram cards, computerized training programs are used to improve fusional vergence.^[8]
• The wearing of convex lenses
• The wearing of concave lenses
• "Cawthorne Cooksey Exercises" also employ various eye exercises, however, these are designed to alleviate vestibular disorders, such as dizziness, rather than eye problems.^[9]
• Antisuppression exercises - this is being less commonly practiced, although occasionally it may be used.

There is widespread acceptance of orthoptic therapy indications for:

• Convergence insufficiency. Patients who experience eyestrain, "tired" eyes, or diplopia (double vision) while reading or performing other near work, and who have convergence insufficiency may benefit from orthoptic treatment. Patients whose outward drift occurs at distance rather than at near distance are less ideal candidates for treatment.
• Intermittent exotropia.^[10] This is often linked to convergence insufficiency.

Convergence insufficiency is a common binocular vision disorder characterized by asthenopia, eye fatigue and discomfort.^[11] Asthenopia may be aggravated by close work and is thought by some to contribute to reading inefficiency.^[6] In 2005, the Convergence Insufficiency Treatment Trial (CITT) published two large, randomized clinical studies examining the efficacy of orthoptic vision therapy in the treatment of symptomatic convergence insufficiency. Although neither study examined reading efficiency or comprehension, both demonstrated that computerized home orthoptic exercises, when combined with weekly in-office vision therapy, were more effective than "pencil pushups" (a commonly prescribed home-based treatment) for improving the symptoms of asthenopia and the convergence ability of the eyes.^[12][13] The design and results of at least one of these studies has been met with some reservation, questioning the conclusion as to whether intensive office-based treatment programs are truly more efficacious than a properly implemented home-based regimen.^[14] The CITT has since published articles validating its research and treatment protocols.^[15][16] Its most recent publication suggested that home-based computer therapy ^[17] combined with office based vision therapy is more effective than pencil pushups or home-based computerised therapy alone for the treatment of symptomatic convergence insufficiency.^[18]

Behavioural visual therapy

Behavioural VT aims to treat problems including difficulties of visual attention and concentration,^[19] which behavioral optometrists classify as visual information processing weaknesses. These manifest themselves as an inability to sustain focus or to shift focus from one area of space to another.^[20] Some assert that poor eye tracking affects reading skills, and that improving tracking can improve reading.^[21]

This includes vision therapy for: Peripheral Vision, Color Perception, Gross Visual-Motor, Fine Visual-Motor, and Visual Perception.^[7]

Some of the exercises involve the use of:

• Marsden balls
• Rotation trainers
• Syntonics
• Balance board/beams
• Saccadic fixators
• Directional sequencers

Behavioral vision therapy is practiced primarily by optometrists after doing extra studies in this area. Major optometric organizations, including the American Optometric Association, the American Academy of Optometry, the College of Optometrists in Vision Development, and the Optometric Extension Program, support the assertion that non-strabismic visual therapy does not directly treat learning disorders, but rather addresses underlying visual problems which are claimed to affect learning potential.^[22]

Major organizations, including the International Orthoptic Association and the American Academy of Ophthalmology have alternatively so far concluded that there is no current validity for clinically significant improvements in vision with Behavioural Vision Therapy, therefore they do not practice it.

Efficacy of behavioral visual therapy

In 1988, a review of 238 scientific articles was published in the Journal of the American Optometric Association widely defined vision therapy as "a clinical approach for correcting and ameliorating the effects of eye movement disorders, non-strabismic binocular dysfunctions, focusing disorders, strabismus, amblyopia, nystagmus, and certain visual perceptual (information processing) disorders." - and thereby did not discriminate between orthoptic and behavioural visual therapy. The paper was positive about vision therapy generally: "It is evident from the research that there is scientific support for the efficacy of vision therapy in modifying and improving oculomotor, accommodative, and binocular system disorders, as measured by standardized clinical and laboratory testing methods for patients of all ages for whom it is properly undertaken and employed."^[23]

A more recent (2005) review concluded less positively that: "Less robust, but believable, evidence indicates visual training may be useful in developing fine stereoscopic skills and improving visual field remnants after brain damage. As yet there is no clear scientific evidence published in the mainstream literature supporting the use of eye exercises in the remainder of the areas reviewed, and their use therefore remains controversial."^[24]

In 2006, noted neurologist Oliver Sacks published a case study about "Stereo Sue", a woman who had regained her stereo vision, absent for 48 years, after undergoing vision therapy. The article was published in The New Yorker magazine, which is fact-checked but not peer-reviewed, very few details were given of the exact therapies used and the article discussed only one case of stereopsis recovery.^[25] However, the woman described by Sacks, Susan Barry, a neurobiology professor at Mt. Holyoke College, subsequently published a book, "Fixing My Gaze." The book discusses multiple case histories and details the therapy procedures and the science underlying them.

A systematic review of the literature on the effects of vision therapy on visual field defects published in 2007 concluded that it was unclear to what extent patients benefited from vision restoration therapy (VRT) as "no study has given a satisfactory answer." The authors concluded that scanning compensatory therapy (SCT) seemed to provide a more successful rehabilitation, and simpler training techniques, therefore they recommended SCT until the effects of VRT could be defined.^[26]

A 2008 review of the literature concluded that "there is a continued paucity of controlled trials in the literature to support behavioural optometry approaches. Although there are areas where the available evidence is consistent with claims made by behavioural optometrists ... a large majority of behavioural management approaches are not evidence-based, and thus cannot be advocated."^[27]

Other than for strabismus (such as intermittent exotropia^[10]) and convergence insufficiency, the consensus among ophthalmologists, orthoptists and pediatricians is that non-strabismic visual therapy lacks documented evidence of effectiveness.^[24][28] In 1998, the American Academy of Pediatrics, American Academy of Ophthalmology, and American Association for Pediatric Ophthalmology and Strabismus issued a policy statement regarding the use of vision therapy specifically for the treatment of learning problems and dyslexia. According to the statement: "No scientific evidence exists for the efficacy of eye exercises ('vision therapy')... in the remediation of these complex pediatric neurological conditions."^[29] More recently, in 2004, the American Academy of Ophthalmology released a position statement asserting that there is no evidence that vision therapy retards the progression of myopia, no evidence that it improves visual function in those with hyperopia or astigmatism, or that it improves vision lost through disease processes.^[30] This was also supported by the International Orthoptic Association.^[31]

The Joint Statement mentioned above^[29] was criticised at the time by Merrill Bowan, a vision therapy enthusiast, for being biased, with the author of a rebuttal concluding "The AAP/AAO/AAPOS paper contains errors and internal inconsistencies. Through highly selective reference choices, it misrepresents the great body of evidence from the literature that supports a relationship between visual and perceptual problems as they contribute to classroom difficulties.".^[32] The author also states that the Joint Statement presents an unsupported opinion by implication that Optometrists claim that vision therapy cures the learning problem. A similar criticism could be levelled at the 2004 American Academy of Ophthalmology paper which implies that vision therapy is claimed to treat "vision lost through disease processes". There is a common theme that critics of vision therapy seem to do by placing vision therapy under the same banner with alternative therapies.^[33] By implication, the lack of evidence for the alternative therapies is cited as a lack of evidence for vision therapy. No supporting evidence is given that vision therapy is actually used to treat eye disease or vision lost through disease processes.

Some optometrists take a slightly different view. In 1999 a joint statement by the American Academy of Optometry, the American Optometric Association, the College of Optometrists in Vision Development and Optometric Extension Program Foundation reported: "Many visual conditions can be treated effectively with spectacles or contact lenses alone; however, some are most effectively treated with vision therapy....Research has demonstrated that vision therapy can be an effective treatment option for ocular motility problems, non-strabismic binocular disorders, strabismus, amblyopia, accommodative disorders (and) visual information processing disorders."^[34]

Practitioners in Behavioral optometry (also known as functional optometrists or optometric vision therapists) practice methods that have been characterized as a complementary alternative medicine practice.^[35] A review in 2000 concluded that there were insufficient controlled studies of the approach^[36] and a 2008 review concluded that "a large majority of behavioural management approaches are not evidence-based, and thus cannot be advocated."^[27]

The consensus among Ophthalmologists, Orthoptists and Pediatricians is that "visual training" in non-strabismic Behavioural Vision therapy lacks documented scientific evidence of effectiveness.^[24][28] Although Ophthalmologists and Orthoptists believe that exercises can improve binocular vision control, they believe it does not purely improve monocular visual acuity such as that in amblyopia (rather, occlusion is the therapy of choice),^[37] change a person's refractive error. It is probable that they do not change the accommodative/convergence ratio nor change the amplitude of accommodation to postpone or delay presbyopia.^[28] It has been considered that they are unlikely to a person to develop the ability for stereopsis;^[28] nonetheless recent experimental investigations into dedicated perceptual learning exercises, inspired by Barry's recovery of stereopsis, have shown some promise.^[38][39]

Eye exercises

The eye exercises used in vision therapy can generally be divided into two groups; those employed for "strabismic" outcomes and those employed for "non-strabismic" outcomes, to improve eye health.

Some of the exercises used are

• Near point of convergence training, or the ability for both eyes to focus on a single point in space,
• Base-out prism reading, stereogram cards, computerized training programs are used to improve fusional vergence.^[40]
• The wearing of convex lenses^[41]
• The wearing of concave lenses
• "Cawthorne Cooksey Exercises" also employ various eye exercises, however, these are designed to alleviate vestibular disorders, such as dizziness, rather than eye problems.^[9]
• Antisuppression exercises - this is no longer commonly practiced, although occasionally it may be used.

The eye exercises used in Behavioural Vision Therapy, also known as Developmental Optometry is practiced primarily by Behavioural Optometrists. Behavioural Vision Therapy aims to treat problems including difficulties of visual attention and concentration, which may manifest themselves as an inability to sustain focus or to shift focus from one area of space to another.

Some of the exercises used are:

• Marsden balls
• Rotation trainers
• Syntonics
• Balance board/beams
• Saccadic fixators
• Directional sequencers

Ophthalmologists and orthoptists do not endorse these exercises as having clinically significant validity for improvements in vision. Usually they see these perceptual-motor activities being in the sphere of either speech therapy or occupational therapy.

Fusional Amplitude and Relative Fusional Amplitude training

• Designed to alleviate convergence insufficiency. The CITT study (Convergence Insufficiency Treatment Trial) was is a randomized, double blind multi-centre trial (high level of reliability) indicates that Orthoptic Vision Therapy is an effective method of treatment of convergence insufficiency (CI). Both optometry and ophthalmology were co-authors of this study.
• Designed to alleviate intermittent exotropia^[42] or other less common forms of strabismus.

Other forms

Certain do-it-yourself eye exercises are claimed by some to improve visual acuity by reducing or eliminating refractive errors. Such claims rely mainly on anecdotal evidence, and are not generally endorsed by orthoptists, ophthalmologists or optometrists.

^[43][44] Chinese school children always do eye exercises twice per day during school, which are compulsory. They are also part of other forms category's as they are also do-it-yourself exercises although quite a few scientists say that they actually harm the children's eyes^[45]

The German optician Hans-Joachim Haase developed a method to correct an alleged misalignment. His method, called the MKH method, is not recognized as an evidence-based approach.^{[46][47][48][49]}

Controversy

Some physicians are skeptical about the efficacy of "vision therapy" stating that it lacks data and is mostly anecdotal.^[50] In 2009, the American Academy of Pediatrics along with the American Academy of Ophthalmology "essentially declared war" on developmental optometry, as Judith Warner wrote in a New York Times article.^[50][51] Even within the field of optometry the U.K. College of Optometrists noted the "Continued absence of rigorous scientific evidence to support behavioral management approaches" in the second college of Optometrists report.^[51] The American Academy of Pediatrics also essentially declared war on behavioral optometry. In 2009 it reviewed 35 years of the literature in support of vision therapy and issued a statement — in conjunction with other ophthalmological associations — condemning the therapy and its contention that it could help with learning disabilities. Visual problems, it claimed, are not the basis for learning disabilities.^[51] It issued a stern warning about the seductions of treatments that sound convincing but aren’t based on science: "Ineffective, controversial methods of treatment such as vision therapy may give parents and teachers a false sense of security that a child’s learning difficulties are being addressed, may waste family and/or school resources and may delay proper instruction or remediation."^[51] The website by the American Association for Pediatric Ophthalmology and Strabismus states: "Behavioral vision therapy is considered to be scientifically unproven" and "There is no evidence that vision therapy delays the progression or leads to correction of myopia."^[52]

History

Development

Various forms of visual therapy have been used for centuries.^[28] The concept of vision therapy was introduced in the late nineteenth century for the non-surgical treatment of strabismus. This early and traditional form of vision therapy was the foundation of what is now known as orthoptics.^[53]

In the first half of the twentieth century, orthoptists, working with ophthalmologists, introduced a variety of training techniques mainly designed to improve binocular function. In the second half of the twentieth century, vision therapy began to be used by optometrists and paramedical personnel to treat conditions ranging from uncomfortable vision to poor reading and academic performance. It has also been used specifically to improve eyesight, and even to improve athletic performance.^[28]

At the beginning of the twenty-first century, most vision therapy is done by optometrists, while traditional orthoptics continues to be practiced by orthoptists and ophthalmologists. Based on assessments of claims and studies of published data, ophthalmologists claim that, except for near point of convergence exercises, vision therapy lacks documented evidence of effectiveness.^[28]

See also

• Bates method, a controversial method aimed at correcting refractive errors
• Behavioral optometry
• Brock string, invented by Frederick W. Brock
• Scotopic sensitivity syndrome, a controversial disorder often treated with colored glasses or overlays
• Orthoptist

References