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."^[1]

Historical development

Various forms of visual therapy have been used for centuries.^[2] 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.^[3][4] 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^[5] 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^{[citation needed]} It is commonly practiced by optometrists and behavioral optometrists - however, more specialized problems are co-managed between orthoptists and ophthalmologists.^[3][6]

• 2) Behavioral Vision Therapy, or Visual Integration Vision Therapy (also known as behavioral or developmental optometry).^[1]

Behavioural Vision Therapy does not limit itself to disorders of the visual system. For example, Behavioral Optometrists hold that the sensitivity of a professional athlete's 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.^{[citation needed]} Ophthalmologists and orthoptists do not endorse these exercises as having clinically significant validity for improvements in vision. Furthermore, absent of any visual pathology they view perceptual-motor deficiencies as being in the sphere of either speech therapy, occupational therapy or physical therapy.

• 3) Perception (motor) Therapy

Although the problems may have visual consequences, the visual system itself may be intact. Common management of dyslexia and sensory processing disorders by Speech Pathologists and Occupational Therapists for pathological or neurological conditions such as hemispatial neglect is viewed as outside of the realm of what is classified here as 'behavioural vision therapy'. This differentiation is primarily based on these disorders having widespread and independent efficacy of treatment.

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.^[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.^[1] 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.^[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 [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.^[17]

Behavioural visual therapy

Behavioural 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.^{[citation needed]} Some assert that poor eye tracking affects reading skills, and that improving tracking can improve reading.^[18]

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.^[19]

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 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."^[20]

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."^[21]

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.^[22] 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.^[23]

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."^[24]

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.^[2][21] 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."^[25] 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.^[26] This was also supported by the International Orthoptic Association.^[27]

The Joint Statement mentioned above^[25] 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.".^[28] 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.^{[citation needed]}

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."^[29]

Economic bias in efficacy

Some skeptics assert that vision therapists may have a financial bias in proclaiming the efficacy of the practice,^[30][31] Common initial assessment prices in the UK range around £300 to £400 ^[32] but in the USA may amount to thousands of dollars for a series.^[33] Most insurance companies do not cover vision therapy services, partly because of the lack of support for vision therapy in evidence-based literature.

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 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.^[34]
• 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 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^[35] or other less common forms of strabismus.

The consensus among Ophthalmologists, Orthoptists and Pediatricians is that "visual training" in non-strabismic Behavioural Vision therapy lacks documented scientific evidence of effectiveness.^[2][36] 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, improve general physical fitness or agility or improve intelligence. It is probable that they do not change the accommodative/convergence ratio or enable someone to develop the ability for stereopsis. It is likely that they do not change the amplitude of accommodation to postpone or delay presbyopia.^[38]

Behavioral optometrists

Main article: Behavioral optometry

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.^[39] A review in 2000 concluded that there were insufficient controlled studies of the approach^[40] and a 2008 review concluded that "a large majority of behavioural management approaches are not evidence-based, and thus cannot be advocated."^[24]

Other forms

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.^[30][41]

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

References

1. ^ ^{a b c} American Academy of Ophthalmology. Complementary Therapy Assessment: Vision Therapy for Learning Disabilities. Retrieved August 2, 2006.
2. ^ ^{a b c} Helveston, EM (2005). "Visual training: current status in ophthalmology". American journal of ophthalmology 140 (5): 903–10. doi:10.1016/j.ajo.2005.06.003. PMID 16310470. 
3. ^ ^{a b} http://www.ranzco.edu/orthoptists-and-prescribing-in-nsw/view?searchterm=None
4. ^ Georgievski Z, Koklanis K, Fenton A, Koukouras I. Victorian orthoptists' performance in the photo evaluation of diabetic retinopathy. Clinical & Experimental Ophthalmology, 2007, 35(8): 733-738. [Pubmed Link]
5. ^ Aetna. Aetna Clinical Policy Bulletins: Vision Therapy. Retrieved August 2, 2006.
6. ^ http://joboutlook.gov.au/pages/occupation.aspx?search=skillshortages&code=2514
7. ^ ^{a b} COVD. [1] Retrieved July 27, 2010.
8. ^ ^{a b} Bartis, MJ. Convergence Insufficiency. eMedicine. January 25, 2005.
9. ^ http://www.dizziness-and-balance.com/treatment/cawthorne.html
10. ^ ^{a b} Zhang KK, Koklanis K, Georgievski Z. Intermittent exotropia: A review of the natural history and non-surgical treatment outcomes. Australian Orthoptic Journal, 2007, 39(1): 31-37.
11. ^ Bartiss M. "Convergence Insufficiency." eMedicine.com. Retrieved August 2, 2006.
12. ^ Scheiman, M; Mitchell, GL; Cotter, S; Cooper, J; Kulp, M; Rouse, M; Borsting, E; London, R et al. (2005). "A randomized clinical trial of treatments for convergence insufficiency in children". Archives of ophthalmology 123 (1): 14–24. doi:10.1001/archopht.123.1.14. PMID 15642806. 
13. ^ Scheiman M, Mitchell GL, Cotter S, Kulp MT, Cooper J, Rouse M, Borsting E, London R, Wensveen J. "A randomized clinical trial of vision therapy/orthoptics versus pencil pushups for the treatment of convergence insufficiency in young adults." Optom Vis Sci. 2005 Jul;82(7):583-95. PMID 16044063.
14. ^ Kushner, BJ (2005). "The treatment of convergence insufficiency". Archives of ophthalmology 123 (1): 100–1. doi:10.1001/archopht.123.1.100. PMID 15642819. http://www.visiontherapy.org/vision-therapy/pdfs/editorial.pdf. 
15. ^ Kulp et al.Convergence Insufficiency Treatment Trial (CITT) Investigator Group Feasibility of using placebo vision therapy in a multicenter clinical trial.Optom Vis Sci. 2008 Apr;85(4):255-61.
16. ^ Convergence Insufficiency Treatment Trial (CITT) Study Group.The convergence insufficiency treatment trial: design, methods, and baseline data. Ophthalmic Epidemiol. 2008 Jan-Feb;15(1):24-36.
17. ^ Convergence Insufficiency Treatment Trial Study Group: Randomized clinical trial of treatments for symptomatic convergence insufficiency in children. Arch Ophthalmol 126: 1336-1349, 2008
18. ^ http://www.childrensvision.com/vision_therapy.htm
19. ^ "Vision, learning and dyslexia. A joint organizational policy statement of the American Academy of Optometry and the American Optometric Association". Journal of the American Optometric Association 68 (5): 284–6. 1997. PMID 9170793. http://www.aoa.org/x1910.xml. 
20. ^ The 1986/1987 Future of Visual Development/Performance Task Force. "Special Report: The efficacy of optometric vision therapy." J Am Optom Assoc. 1988;59:95-105. PMID 3283203
21. ^ ^{a b} Rawstron JA, Burley CD, Elder MJ (2005). "A systematic review of the applicability and efficacy of eye exercises". J Pediatr Ophthalmol Strabismus 42 (2): 82–8. PMID 15825744. 
22. ^ Oliver Sacks (June 19, 2006). "A Neurologist's Notebook: "Stereo Sue"". The New Yorker. pp. 64. 
23. ^ Bouwmeester L, Heutink J, Lucas C. (2007). "The effect of visual training for patients with visual field defects due to brain damage: a systematic review". J Neurol Neurosurg Psychiatry 78 (6): 555–64. doi:10.1136/jnnp.2006.103853. PMC 2077942. PMID 17135455. http://jnnp.bmj.com/content/78/6/555.long. 
24. ^ ^{a b} Brendan T. Barrett (2008). "A critical evaluation of the evidence supporting the practice of behavioural vision therapy". Ophthalmic and Physiological Optics 29 (1): 4–25. doi:10.1111/j.1475-1313.2008.00607.x. PMID 19154276. 
25. ^ ^{a b} "Policy Statement: Learning Disabilities, Dyslexia, and Vision". American Academy of Pediatrics, American Association for Pediatric Ophthalmology and Strabismus, American Academy of Ophthalmology.. September, 1998. http://www.aao.org/about/policy/upload/Learning-Disabilities-Dyslexia-and-Vision.pdf. 
26. ^ "Complementary Therapy Assessment: Vision Training for Refractive Errors". American Academy of Ophthalmology. 2004. Archived from the original on 2007-10-15. http://web.archive.org/web/20071015183505/http://aao.org/education/guidelines/cta/training.cfm. Retrieved 2008-04-09. 
27. ^ http://www.internationalorthoptics.org/
28. ^ Bowan, M. Learning disabilities, dyslexia, and vision: a subject review--a rebuttal, literature review, and commentary. Optometry. 2002 Sep;73(9):553-75.
29. ^ "Vision Therapy a joint organizational policy statement". American Academy of Optometry. 1999. http://covd.org/Portals/0/Vision-Therapy%20-%20JOPS%20AAO%20&%20AOA.pdf. 
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31. ^ http://www.quackwatch.com/01QuackeryRelatedTopics/eyequack.html
32. ^ http://www.childopt.co.uk/pricelist.htm
33. ^ http://www.srmhp.org/archives/vision-therapy.html
34. ^ http://www.dizziness-and-balance.com/treatment/rehab/cawthorne.html
35. ^ Zhang KK, Koklanis K, Georgievski Z. Intermittent Exotropia: A Review of the Natural History and Non-surgical Treatment Outcomes. Australian Orthoptic Journal, 2007;39(1):31-37.
36. ^ Rawstron JA, Burley CD, Elder MJ (2005). "A systematic review of the applicability and efficacy of eye exercises.". J Pediatr Ophthalmol Strabismus 42 (2): 82–8. http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=15825744&query_hl=13&itool=pubmed_DocSum.
37. ^ Georgievski, Z; Koklanis, K; Leone, J (2007). "Orthoptists' management of amblyopia - a case-based survey". Strabismus 15 (4): 197–203. doi:10.1080/09273970701631975. PMID 18058356. 
38. ^ name="Helveston">Helveston, EM (2005). "Visual training: current status in ophthalmology". American journal of ophthalmology 140 (5): 903–10. doi:10.1016/j.ajo.2005.06.003. PMID 16310470. 
39. ^ Torin Monahan. "Vision Control and Autonomy Constraints: Managed Care Confronts Alternative Medicine." June 1998. Accessed September 19, 2006.
40. ^ Jennings (2000). "Behavioural optometry – a critical review". Optom. Pract. 1 (67). 
41. ^ Rob Murphy, Marilyn Haddrill (December 2006). "The See Clearly Method: Do Eye Exercises Improve Vision?". AllAboutVision.com. http://www.allaboutvision.com/buysmart/see_clearly.htm.