Vision therapy

Vision therapy, also known as visual training, vision training, or visual therapy, is a group of techniques attempting variously to correct or improve presumed ocular, oculomotor, visual processing, and perceptual disorders." ^[1] Vision therapy encompasses a wide variety of non-surgical methods^[2] which some have divided into two broad categories: 1) orthoptic vision therapy, also known as orthoptics, and 2) behavioral vision therapy, also known as behavioral or developmental optometry.^[1]

Orthoptics aims to treat binocular vision disorders such as strabismus, and diplopia. It is practiced by optometrists and ophthalmologists, as well as orthoptists under the guidance of some ophthalmologists and pediatric ophthalmologists.

Behavioral vision therapy is practiced primarily by optometrists who specialize in this field. It treats additional problems including difficulties of visual attention and concentration, which may manifest as an inability to sustain focus or to shift focus from one area of space to another. The ability to shift the focus of visual attention from one place in space to another affects many aspects of life including reading, most vocations and most avocations. Eye doctors may also prescribe vision therapy to sufferers from eye strain and visually-induced headaches. However, not all such therapy is limited to disorders of the visual system. Professional athletes, for example, may use vision therapy to enhance sensitivity to peripheral vision on the playing field or increase responsiveness to fast moving objects.

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History

Various forms of visual therapy have been used for centuries.^[3] The concept of vision therapy was introduced in the late nineteenth century for the non-surgical treatment of misaligned eyes. This early and traditional form of vision therapy is what is now known as 'orthoptics.' Collaboration of some eye care professionals with educators and neuroscientists produced an expansion of vision therapy into the treatment of other eye teaming (binocular) deficits (the use of the flow through the right and left eyes simultaneously to the brain) 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.

Although ophthalmologists and orthoptists often perform several components of visual therapy, most non-strabismic VT is performed by optometrists.^[3]

Indications

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.

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 vision therapy does not directly treat learning disorders, but rather addresses underlying visual problems which are claimed to affect learning potential.^[4]

Advocates cite a number of indications for the use of vision therapy. Some assert that poor eye tracking affects reading skills, and that improving tracking can improve reading.^[5]

Efficacy

In 1988, a review of 238 scientific articles was published in the Journal of the American Optometric Association defining 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." The paper concluded, "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."^[6]

Convergence insufficiency is a common binocular vision disorder characterized by asthenopia, eye fatigue and discomfort.^[7] Asthenopia may be aggravated by close work and is thought by some to contribute to reading inefficiency.^[1] In 2005, the Convergence Insufficiency Treatment Trial 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.^[8][9] 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.^[10]

Skepticism

Other than for near point of convergence exercises, the consensus among ophthalmologists is that visual training lacks documented evidence of effectiveness.^[3] 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." ^[11] In 2004, the American Academy of Ophthalmology released a similar position statement asserting that there is no evidence that vision therapy retards the progression of myopia, that it improves visual function in those with hyperopia or astigmatism, or that it improves vision lost through disease processes.^[12]

Although skeptics assert that vision therapists may have a financial bias in proclaiming the efficacy of the practice^[13], proponents of vision therapy claim that other eye professionals have a similar bias in rejecting its claims.^[14]

References