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.*
Historical developmentVarious 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 strabismus. This early and traditional form of vision therapy was the foundation of what is now known as orthoptics.*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.*
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.*
Current definitions in clinical practiceVision Therapy encompasses a wide variety of non-surgical methods* which may be divided into two broad categories:
Orthoptic visual therapyOrthoptics 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:
There is widespread acceptance of orthoptic therapy indications for:
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 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 (eye)|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 * 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 therapyBehavioural VT aims to treat problems including difficulties of visual attention and concentration, 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. Some assert that poor eye tracking affects reading skills, and that improving tracking can improve reading.*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:
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.*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 therapyIn 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 stereopsis recovery.* However, the woman described by Sacks, Susan R. Barry|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|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."*Practitioners in Behavioral optometry (also known as functional optometrists or optometric vision therapists) practice methods that have been characterized as a alternative medicine|complementary alternative medicine practice.* A review in 2000 concluded that there were insufficient controlled studies of the approach* and a 2008 review concluded that "a large majority of behavioural management approaches are not evidence-based, and thus cannot be advocated."*The consensus among Ophthalmologists, Orthoptists and Pediatricians is that "visual training" in non-strabismic Behavioural Vision therapy lacks documented scientific evidence of effectiveness.* 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),* change a person's refractive error, improve general physical fitness or agility or improve intelligence. It is probable that they do not change the accommodative/convergence ratio nor change the amplitude of accommodation to postpone or delay presbyopia.* It has been considered that they are unlikely to a person to develop the ability for stereopsis;* nonetheless recent Stereopsis recovery#Stereopsis following training procedures|experimental investigations into dedicated perceptual learning exercises, inspired by Barry's recovery of stereopsis, have shown some promise.*
Eye exercisesThe 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
The eye exercises used in Behavioural Vision Therapy, also known as Developmental Optometry is practiced primarily by Behavioural Optometrists. Behavioural Vision Therapy 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:
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