Vision therapy

Vision therapy, also known as visual training, vision training, or visual therapy, is a broad group of techniques aimed at correcting and improving binocular, oculomotor, visual processing, and perceptual disorders."

Historical development

Various forms of visual therapy have been used for centuries. The concept of vision therapy was introduced in the late nineteenth century for the non-surgical treatment of misaligned eyes (strabismus). This early and traditional form of vision therapy is what is now known as 'orthoptics' - although this term does not limit the work of Orthoptists who today often work beyond the realm of strabismus. Collaboration of some Eye care professionals with educators and neuroscientists produced an expansion of vision therapy into the treatment of other eye coordination (binocular) deficits as well as dysfunctions in visual focusing, perception, tracking and motor skills.

As a result of this expansion and ensuing confusion over what the term "vision therapy" includes, there is some controversy as to the use of vision therapy for individuals with learning disorders.

Current definitions in clinical practice

Vision Therapy encompasses a wide variety of non-surgical methods which some have divided into two broad categories based on their clinical acceptance and general practice by eyecare professionals:

• 1) Orthoptic Vision Therapy, also known as orthoptics.

It may be prescribed to patients with problems of visual related skills required for reading, eye strain, visually-induced headaches, strabismus and/or diplopia It is commonly practiced by optometrists and behavioral optometrists - however, more specialized problems are co-managed between orthoptists and ophthalmologists.

• 2) Behavioral Vision Therapy, or Visual Integration Vision Therapy (also known as behavioral or developmental optometry).

Behavioural Vision Therapy does not limit itself to disorders of the visual system. For example, Behavioral Optometrists hold that the sensitivity of a Professional athletes peripheral vision on the playing field may have enhanced responsiveness to fast moving objects with vision therapy, beyond the normal realm general improvement with practicing their sport. 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, occupational therapy or physical therapy.

Orthoptic Visual Therapy

for more detail, see also Orthoptics.

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. .

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.
• 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.
• 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. This is often linked to convergence insufficiency.

Convergence insufficiency is a common binocular vision disorder characterized by asthenopia, eye fatigue and discomfort. Asthenopia may be aggravated by close work and is thought by some to contribute to reading inefficiency. 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 in-office vision therapy was more effective than "pencil pushups" (a commonly prescribed home-based treatment) for improving the symptoms of asthenopia and the convergence ability of the eyes. 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. The CITT has since published articles validating its research and treatment protocols. Its most recent publication suggested that home-based computer therapy[2] 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.

Behavioural Visual Therapy

Behavioral vision therapy is practiced primarily by optometrists who specialize in this field. Behavioural VT 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.

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

Some of the exercises involve the use of:

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

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.

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.

Advocates cite a number of indications for the use of non-strabismic vision therapy. Some assert that poor eye tracking affects reading skills, and that improving tracking can improve reading.

Efficacy of behavioural 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."

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."

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 stereo rehabilitation. 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.

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."

Other than for strabismus (such as intermittent exotropia) and convergence insufficiency, the consensus among ophthalmologists, orthoptists and pediatricians is that non-strabismic visual therapy lacks documented evidence of effectiveness. 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." 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. This was also supported by the International Orthoptic Association.

The Joint Statement mentioned above 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." . 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. 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."

Although skeptics assert that vision therapists may have a financial bias in proclaiming the efficacy of the practice, proponents and advocates of vision therapy claim that other eye professionals have a similar bias in rejecting its claims. In either case, most insurance companies do not cover vision therapy services, partly because of the lack of support for vision therapy in evidence-based literature.

See also

• Bates method, a controversial method aimed at correcting refractive errors
• Scotopic sensitivity syndrome, a controversial disorder often treated with colored glasses or overlays
• Orthoptist