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==External links==
==External links==
*[http://www.dmoz.org/Health/Senses/Vision/ DMOZ Open Directory - Vision]
*[http://www.dmoz.org/Health/Senses/Vision/ DMOZ Open Directory - Vision]
*[http://www.i-see.org/ ISee International Society for the Enhancement of Eyesight ]






Revision as of 20:34, 18 October 2007

The Bates method of natural vision improvement is a program created by ophthalmologist William Horatio Bates, M.D., which aims to correct what Bates, and teachers of the Bates method, see as faulty vision habits through relaxation techniques, exercises and optional activities and games.[1] Bates claimed that his program improves sight and reverses ocular disorders to normal. It is argued by proponents that it works by eliminating "mental strain" of any kind and by restoring the "natural habits" of seeing. The Bates Method is the backbone of the natural vision improvement movement . The Bates method was first described in 1920 in a book entitled Perfect Sight Without Glasses, and then subsequently in his monthly magazine entitled Better Eyesight (1919-1930).

Although many people claim to have been helped by the method, the efficacy of the Bates method is controversial.[2] His theory that the eye does not focus by changing the power of the lens, but rather by elongating the eyeball, through use of the extraocular oblique muscles, was contradicted by mainstream ophthalmology and optometry of his day and is still today.[3][4]

Bates' Publications

In 1943 Bates' widow, Emily Bates, published an abridged version of his book Perfect Sight Without Glasses under the title Better Eyesight Without Glasses. These abridged versions watered-down many of the wilder claims, such as "imagining black" being a suitable substitute for anaesthesia or claims related to staring at the sun (see below).[4] Because the copyrights are over 70 years old the original version is available free on the internet (see links).

Bates' theories

Bates theorized that various types of "mental strain" were responsible not only for refractive errors (such as myopia, hyperopia, astigmatism, and presbyopia), but also for other abnormal eye conditions including strabismus, cataracts, glaucoma, amblyopia, conjunctivitis, blepharitis, and diseases of the optic nerve and retina.[5] According to Bates, relaxation was the only cure for each type of strain.[5]

Accommodation by extraocular muscle squeezing

Accommodation is the process by which the eye increases optical power to maintain focus on the retina. So when the eyes change from viewing a distant object to a near object accommodation is taking place.

Bates rejected the orthodox view that accommodation was brought about by the action of the ciliary muscle on the eye's crystalline lens[6], and claimed that focus was maintained by varying elongation of the eyeball caused by the extraocular muscles. Bates claimed that the lens played no part in accommodation and reported that the extraocular muscles, and in particular the oblique muscles, squeeze the eyeball to obtain focus by elongation. Excessive tension of the recti muscles may also make, according to Bates, the eyeball too short (leading to hyperopia, and excessive tension of the oblique and recti muscles makes the eye astigmatic).

Bates regarded the superior and inferior oblique muscles as "the muscles of accommodation".[7]

Refractive errors due to extraocular muscle squeezing

Bates regarded the refractive state of the eye as variable and disregarded the notion that permanent changes in the shape of the eyeball caused refractive errors. Instead, he stated that the shape of the eyeball responded instantly to the action of the extraocular muscles upon it.[8]

Bates claimed that straining to see at the near-point led to shortening of the eyeball resulting in hypermetropia (farsightedness), and that straining to see at the far-point led to lengthening of the eyeball leading to myopia (nearsightedness). At first this seems back-to-front, but by straining to see at the near-point Bates did not mean habitual close-work, or even tensing of the muscles, he meant 'straining' in a mental sense.[citation needed] He makes this clear in his chapter entitled 'strain' where he says, "if the muscles respond to the minds desire, they do so without strain". Some have assumed that Bates saw prolonged tension in the extraocular muscles as directly causing eyeball deformation [9]. His 'mental strain' is quite unconnected with muscle tension, and he sees the maladjustment as being in the brain, not the eye[citation needed].

Bates concluded that myopia was related to apprehension, or what some may call "anxiety". He reportedly felt that good vision was nature's way, and that any other way was a strained way of seeing. Bates believed that it was impossible to consciously relieve the eyes of this tensing, and instead developed his method as a means of effecting subconscious relaxation.

The concept that relaxing the extraocular muscles can reliably or predictably reduce refractive error has not been substantiated by patients whose muscles are loosened during strabismus surgery. Although small refractive changes may occur following this type of muscle loosening surgery (recession), these alterations are generally small, clinically insignificant, transient, and occur in both directions (stronger and weaker). [10] Additional evidence that the genetic theory[citation needed] is wrong comes from research where scientists[citation needed] deliberately created strabismus in normal monkeys by surgically reattaching an extraocular muscle to the wrong place. They found it difficult to create a permanent state of strabismus and all the monkeys spontaneously straightened their eyes within a few weeks. [11]

Close work

Bates Method advocates believe that viewing books, computer monitors, and other near-vision activities are harmless, in fact a good exercise, as long as a person maintains correct vision habits. They also believe that eyeglasses are at best a crutch and at worst actually make vision with the naked eye worse.

Eyeglasses

Bates wrote: "At their best it cannot be maintained that glasses are anything more than a very unsatisfactory substitute for normal vision."[12] He claimed that eyeglasses injured the eyes and did not restore normal vision.[12] The refractive condition of the eye, he maintained, is constantly changing, from day to day and from hour to hour, and so the prescribing of corrective lenses can only ever be right at the time they are fitted, after which they force the eye to adjust to them.

Bates cited many disadvantages to eyeglasses, maintaining that they adversely affected color perception, contracted the field of vision, and caused dizziness and headaches when the wearer viewed objects off-axis.[12] `

Bates' techniques

Bates claimed to have discovered that people with abnormal vision use their eyes differently than people with normal vision, and then created a system designed to help people to relearn the right vision habits. Advocates of the Bates Method claim that these vision habits are inseparably connected to normal vision. They assert that the Bates Method is a natural method that improves movement, relaxation, and circulation of the whole visual system. Bates' "exercises" are not aimed at muscle strengthening, but, like many yoga practices, are aimed at procuring a state of relaxation. Bates indicated that for his techniques to be effective eyeglasses must be discarded entirely, not simply worn less frequently or in a lower prescription.[13]

Relaxation is at the core of the Bates Method, involving a set of practices which Bates advocates term "exercises in relaxation" and "movement exercises" [14]. They emphasize that the term "exercise" is used in the same sense as "memory exercise" and does not imply muscle strengthening.

Swinging involves deliberate movements of the body with relaxed awareness of vision.

Palming or cupping is one technique that advocates claim achieves relaxation of the mind and the eyes. Palming requires a person to gently cup the palms of the hands over the closed eyelids, and attempt to see "perfect black" in order to give the mind and the visual system as much rest as possible. Then the person sits for five to fifteen minutes (or as long he or she wants) breathing deeply and easily with good posture.

Sunlight exposure involves looking at the sun through closed eyelids. Bates considered light to be the "lifeblood" of healthy eyes. See the discussion on safety below regarding this controversial aspect of his program.

Central fixation was considered very important by Bates. Recognizing that only a very small part of the retina is capable of the highest resolution, he claimed that many people, when reading, allow the central fixation needed to maintain a sharp image to wander, so that they are attempting to focus using a low resolution part of the retina. He emphasized that good fixation is about relaxing and allowing the eyes to change gaze rapidly and naturally, rather than straining to fixate, which results in staring. Staring is the result of tension, according to Bates, and very bad.

Aldous Huxley and Margaret Corbett

The British writer Aldous Huxley (author of Brave New World) was a famous advocate of the Bates method. Huxley claimed to have achieved successful results in his book entitled The Art of Seeing. Huxley was among the students of Margaret Corbett, A "Bates Practitioner", who trained with Dr. Bates in 1930 and later authored Help Yourself to Better Sight.

However, while Huxley undoubtedly believed his vision had improved, Bennett Cerf thought otherwise. In 1952 Cerf was present when Huxley spoke at a Hollywood banquet, wearing no glasses and apparently reading his paper from the lectern without difficulty:

"Then suddently he faltered—and the truth became obvious. He wasn't reading his address—he had learned it by heart. To refresh his memory he brought it closer and closer to his eyes. When it was only an inch away he still couldn't read it, and had to fish for a magnifying glass in his pocket to make the typing visible to him. It was an agonizing moment."[15] (p. 241: quotes Bennett Cerf re Huxley's vision in 1952)

In 1941, Margaret Corbett was brought to trial in California on a charge of practicing medicine without a license, but was acquitted. Later, together with others, including Huxley, she successfully fought a State Bill which would have banned teaching methods of sight improvement and relaxation without a medical or ophthalmic license. [16]

Criticisms of the Bates Method

Theories of accommodation/focusing and refractive errors

Critics of the Bates Method reject the theory that human eyes accommodate, or focus, due to elongation of the eyeball caused by “squeezing” of the extraocular muscles, as has been claimed to happen in some animals. Critics of the Bates Method instead support the mainstream theory set forth by Hermann von Helmholtz that human eyes accommodate, or focus, due to the actions of the ciliary muscle (an intraocular muscle) and zonules changing the shape of the crystalline lens. To support this theory, critics of the Bates Method point to the action of various cycloplegic agents which temporarily paralyze accommodation by relaxing the ciliary muscle but leave the extraocular muscles, which control eye movements, unaffected. Modern equipment, not available to Bates, has made possible the observation of the eye in great detail. Modern observations have shown the lens changing shape when the eye accommodates. [17] Elwin Marg, writing in 1952 points out that "it would take about one millimeter change in axial length of the eyeball for each 3 diopters change of refractive power. Hence, a youth accommodating 15 D would shorted his globe by five millimeters." He continues: "to the writer's knowledge, no corresponding anterior-posterior corneal movement has ever been reported." [4] Another problem with this theory is that if it was true, intraocular lenses couldn't be used to cure presbyopia. [citation needed]

Bates' other source of evidence was the ability of some aphakics to accommodate. Firstly, these cases are exceptionally rare and therefore should be considered exceptions to the rule rather than the rule [4] and, secondly, evidence has been presented that there is no change in the refractive power of the eye in these cases. [18][19]

Critics of the Bates Method contend that if the cause of myopia is continuous tensing of the muscles, either ciliary or extraocular, the Bates Method theory is that it should be possible to cure (or noticeably improve) it by causing intentional relaxation of the muscles; a process most commonly done using injections or topical administration of atropine. The mainstream consensus on this, however, is that no significant improvement of the vision is obtained when muscles are relaxed in this manner. Although Bates claimed that the evidence against the orthodox theory of accommodation was "overwhelming", he acknowledged that the effect of atropine supported the orthodox theory in "about nine cases out of ten".[6][17]

Efficacy

Some behavioral vision therapists continue to practice the Bates method despite research demonstrating lack of efficacy.

Optometrists and ophthalmologists that are aware of his work remain skeptical, to say the least. Skeptic Martin Gardner characterizes Bates's book in Fads and Fallacies in the Name of Science, as "a fantastic compendium of wildly exaggerated case records, unwarranted inferences and anatomical ignorance." Bates theory of accommodation suggested the contraction of the ocular muscles resulted in changes in focusing power rather than changes in the lens and contraction of the lens zonules. Gardner argues that current high-resolution dynamic ultrasonic biomicroscopy has shown Bates' theory of accommodation (by elongation of the eyeball) to be false. Gardner suggested that the Bates method may however work, to a limited degree, by increasing the trainee's ability to interpret and extract information from blurred images.[15]

The purported benefits are generally anecdotal and medical research often shows no clinical benefit. The medical community is often critical of the Bates method and lack of evidence-based medical support.[17][20][21][22]

In the eighties and nineties, interest in biofeedback in turn stimulated some research into the Bates method. It was found in one study that myopes could improve their visual acuity with biofeedback training, but that this improvement was "instrument-specific" and did not generalise to other measures or situations. [23] In another study an "improvement" in visual acuity was found but the authors concluded that this could be a result of subjects learning the task [24] Finally, in an evaluation of a training system designed to improve acuity, "no significant difference was found between the control and experimental subjects" [25] A 1997 review of this biofeedback research concluded that "controlled studies to validate such methods ... have been rare and contradictory." [26]

A 2005 review of the literature on eye exercises concluded that: "Small controlled trials and a large number of cases support the (use of eye exercises in) treatment of convergence insufficiency. Less robust, but believable, evidence indicates visual training may be useful in developing fine stereoscopic skills and improving visual field remnants after brain damage."[2] However, the report also concluded that "no clear scientific evidence" exists for the efficacy of eye exercises in the treatment of "vergence problems, ocular motility disorders, accommodative dysfunction, amblyopia, learning disabilities, dyslexia, asthenopia, myopia, motion sickness, sports performance, visual acuity, and general well-being." [2]

Safety

Avoidance of conventional treatment

Advocates believe the Bates Method to be safe. Critics concede that most of the Bates techniques are harmless, apart from the possibility that faith in the Bates system could deter people with eye conditions requiring prompt care from seeking conventional treatment. Professional Bates Method teachers use a disclaimer, which must be signed by the student, that emphasizes that a Bates Method teacher is not an Ophthalmologist.[27]

In humans the eye and brain development continues until approximately 8-10 years of age. For proper development of the visual pathways in the brain it is essential that clear images fall on the retina. Therefore it is very important that any refractive error is fully corrected in childhood in order to prevent the development of amblyopia.

Sunlight exposure

Bates gives several examples of patients' vision improving after having looked directly at the sun,[28] which in some situations may be dangerous. Figures in Chapter 17 of Bates' 'Perfect Sight Without Glasses' show several individuals looking at the Sun "without discomfort" and figure 48 shows somebody "Focussing the Rays of the Sun Upon the Eye of a Patient by Means of a Burning Glass" implying that this is a safe thing to do.[28] Regarding "sun-gazing" as beneficial he goes so far as to say that: "In some rare cases... complete cures have been effected by this means alone."[28] Regarding looking directly at the sun, Bates also remarks that:

"In my experience such light has never been permanently injurious. Persons with normal sight have been able to look at the sun for an indefinite length of time, even an hour or longer, without any discomfort or loss of vision. Immediately afterward they were able to read the Snellen test card with improved vision, their sight having become better than what is ordinarily considered normal."[28]

According to Thomas R. Quackenbush, Bates modified this suggestion after having written Perfect Sight Without Glasses by stating that the sun should only be allowed to shine on closed eyes.Cite error: The <ref> tag has too many names (see the help page).

Other eye-exercise methods

In recent years, the growing interest in alternative medicine has led to an increase in the popularity of the Bates Method and other methods claiming success via visual training through eye exercises. One particularly controversial area is the efficacy of eye exercises in the treatment of myopia (near-sightedness) and whether the use of eyeglasses makes myopia progressively worse.

Several points of view exist about the use of eye exercises to treat vision problems:

  • Traditional mainstream ophthalmologists and optometrists use eye exercises to treat a limited range of problems, particularly problems involving muscular imbalances and problems with coordination of eye movement between the two eyes. (See orthoptics.)
  • Functional optometrists and optometric vision therapists are licensed, credentialed doctors of optometry, who specialize in treatment that involves eye exercises. They hold that such exercises are useful in improving a wide range of visual conditions, including focusing problems. The methods used are said to be backed by clinical studies and publications in peer-reviewed journals. (See vision therapy.)
  • The Bates method differs from other health systems that use eye exercises in a way that can be categorized as alternative medicine. Like homeopathic medicine, the treatments used and the explanations of how they are said to work are rejected by mainstream medicine[15], despite personal testimony[29] by people who claim to have been helped by such methods.

The See Clearly Method

The See Clearly Method is one program developed by four doctors calling themselves the American Vision Institute and based on their book Improve Your Vision Without Glasses Or Contact Lenses : A New Program Of Therapeutic Eye Exercises. It is an eye-based exercise program marketed as an alternative to the use of glasses, contact lenses, and eye surgery to improve vision. It combines elements of the Bates method, but Bates practitioners are keen to distance themselves from it.[29] The effectiveness of the See Clearly Method is disputed by scientists and mainstream eye care practitioners. According to the official website, eye muscles are like any other muscles, and need regular exercise, although the website also concedes that "no formal research studies have been done yet on the See Clearly Method."

Tom Miller, the Attorney General of Iowa, filed a consumer fraud lawsuit against Vision Improvement Technologies, the promoter of the See Clearly Method, in 2005. In February 2006 an Iowa court issued a temporary injunction restricting certain aspects of the company's marketing.[30]

In November 2006, a court order halted sales of See Clearly kits and ordered the company to pay $200,000 into a restitution fund for consumers allegedly duped into buying the kits through misleading advertising. Iowa Attorney General Tom Miller said that See Clearly made "dramatic claims for its product that could not be substantiated" and "used a combination of misleading and unfair marketing tactics to sell their kits,"[31][32] A consent decree was issued under which the company was ordered to halt sales, offer restitution to customers, clear customers' credit records of any filings related to See Clearly purchases, and halt operations as of December 2006. The company did so [29] and on December 21, 2006, the company's web site stated, "As of November 1, 2006 The See Clearly Method is no longer available for sale."

Pathogenesis and control of myopia: the modern debate

Although not alone in his endeavors, Bates is commonly recognized as one of the first in the modern era to attempt to prevent, arrest, or reverse myopia and other refractive errors. His techniques (designed to eliminate "mental strain") have been largely rejected by mainstream ophthalmology as ineffective[3], but certain pharmaceuticals, contact lenses, and surgeries have achieved varying degrees of success (at least on a temporary basis), as have vision therapy and plus lenses in the treatment of pseudomyopia.[citation needed]

In direct contrast to research over the past ten to twenty years which has implicated heavy amounts of near-work as a contributing factor to the development of myopia[33][34], Bates emphasized that that near-work and "overuse of the eyes" were not necessary to cause myopia, and claimed that he "made many dogs myopic by inducing them to strain to see a distance object". To Bates, refractive errors were due to a "loss of mental control" brought about by "strain", specifically "strain of the mind". He wrote: "The remedy is not to avoid either near work or distant vision, but to get rid of the mental strain which underlies the imperfect functioning of the eye at both points."

Despite considerable evidence that blurred images appear to trigger changes in the axial length of the eyeball through a complex feedback mechanism,[citation needed] some Bates advocates hold the original hypothesis that "mental strain" is ultimately responsible for the development of refractive error through extraocular muscle squeezing of the globe. They contend that various eye exercises could affect a person's refractive error by altering the structure of the eyeball; however, there is no modern research that directly supports these claims.

Natural vision improvement

Bates is credited for being the founder of the Natural vision improvement.[1] Various self-help books and programs exist claiming to improve vision "naturally" by various means.[35][36]

Steven M. Beresford agrees with Bates regarding the possibility of improving eyesight naturally, saying in his book : "Pretending that the traditional use of 'corrective' lenses is safe and effective is no longer acceptable. The public must be told the truth and given accurate information about the alternative methods of treatment now available." In the book, Beresford et al assert that corrective lenses are neither safe or effective and that vision can be improved without the use of glasses or contact lenses.[11]

Natural Vision Improvement markets itself as a lifestyle method of improving eyesight by holistic means without the use of optical devices. It uses the Bates method "merged" with modern theories of brain function, character and responsibility for one’s self and state of being. [37]

See also


References

  1. ^ a b Quackenbush, Thomas. R. (2000). Better Eyesight The complete magazines of William H. Bates. North Atlantic Books. pp. page 643. ISBN 1-55643-351-4. {{cite book}}: |pages= has extra text (help) Cite error: The named reference "Quackenbush" was defined multiple times with different content (see the help page).
  2. ^ a b c 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.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  3. ^ a b Robyn E. Bradley (September 23, 2003). "ADVOCATES SEE ONLY BENEFITS FROM EYE EXERCISES" (PDF). The Boston Globe (MA).
  4. ^ a b c d Marg, E. (1952). ""Flashes" of clear vision and negative accommodation with reference to the Bates Method of visual training". Am J Opt Arch Am Ac Opt. 29 (4): 167–84.
  5. ^ a b William Bates. "Better eyesight without glasses, Chapter 10".
  6. ^ a b William Bates. "Better eyesight without glasses, Chapter 6".
  7. ^ William Bates. "Better eyesight without glasses, Chapter 4".
  8. ^ William Bates. "Better eyesight without glasses, Chapter 7".
  9. ^ http://www.iblindness.org/articles/gottlieb-psych/ch2.html
  10. ^ Preslan M, Cioffi G, Min Y. "Refractive error changes following strabismus surgery". J Pediatr Ophthalmol Strabismus. 29 (5): 300–4. PMID 1432517.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  11. ^ a b Steven M. Beresford, David W. Muris, Merril J. Allen, Francis A. Young. Improve Your Vision Without Glasses Or Contact Lenses : A New Program Of Therapeutic Eye Exercises ( Page 36 and 37 ). Fireside, Inc; 1996. ISBN 0-684-81438-2. Cite error: The named reference "Beresford" was defined multiple times with different content (see the help page).
  12. ^ a b c William Bates. "Better eyesight without glasses, Chapter 8".
  13. ^ William Bates. "Better eyesight without glasses, Chapter 24".
  14. ^ http://www.seeing.org/intro/faq/faq05.htm
  15. ^ a b c Gardner, Martin (1957). Fads and Fallacies in the Name of Science. Reprint: Courier Dover. ISBN 0-486-20394-8.
  16. ^ Cobett's 'Help yourself to better sight'.
  17. ^ a b c Pollack P. The Truth about Eye Exercises. Philadelphia: Chilton Co., 1956, Chapter 3. available online
  18. ^ Bettman, J . W. (1950). "Apparent Accommodation in Aphakic Eyes". Amer. Jour. Ophthal. 33: 921–928.
  19. ^ Hirsch, Monroe J. (1950). "Apparent Accommodation in Aphakia". Amer. Jour. Optom. and Arch. Amer. Acad. Optom. 27: 412–414.
  20. ^ Kavale K, Mattson P.D. "One Jumped Off The Balance Beam": Meta-analysis of Perceptual-motor Training. Journal of Learning Disabilities 16:165-174, 1983.
  21. ^ Keogh BK and Pelland, M. Vision training revisited. Journal of Learning Disabilities 18:228-235, 1985.
  22. ^ Koller H. Is vision therapy quackery? Review of Ophthalmology March:38-49, 1998
  23. ^ Randle RJ (1988). "Responses of myopes to volitional control training of accommodation". Ophthalmic Physiol Opt. 8: 333–340.
  24. ^ Gallaway M, Pearls SM, Winkelstein AM; et al. (1987). "Biofeedback training of visual acuity and myopia: A pilot study". Am J Optom Physiol Opt. 64: 62–71. {{cite journal}}: Explicit use of et al. in: |author= (help)CS1 maint: multiple names: authors list (link)
  25. ^ Koslowe KC, Spierer A, Rosner M; et al. (1991). "Evaluation of accommotrac biofeedback training for myopia control". Optom Vis Sci. 68: 252–4. {{cite journal}}: Explicit use of et al. in: |author= (help)CS1 maint: multiple names: authors list (link)
  26. ^ G Rupolo, M Angi, E Sabbadin, S Caucci, E Pilotto, E Racano and C de Bertolini (1997). "Treating myopia with acoustic biofeedback: a prospective study on the evolution of visual acuity and psychological distress". Psychosomatic Medicine. 59 (3): 313–317.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  27. ^ Disclaimer http://www.visionsofjoy.org/disclaimer.htm
  28. ^ a b c d William Bates. "Better eyesight without glasses, Chapter 17".
  29. ^ a b c Visions of Joy. "Reaction to this court order by the natural vision improvement movement".
  30. ^ Iowa district attorney's office. "Press release on consent decree".
  31. ^ Rob Murphy, Marilyn Haddrill. "The See Clearly Method: Do Eye Exercises Improve Vision?".
  32. ^ Council of Better Business Bureaus, Inc. "Compliance with Iowa court order (Word document)". Electronic Retailing Association. {{cite web}}: |author= has generic name (help)
  33. ^ "Lifestyle causes myopia, not genes". 8th July 2004. {{cite web}}: Check date values in: |date= (help)
  34. ^ Jiang BC, Schatz S, Seger K. (2005). "Myopic progression and dark focus variation in optometric students during the first academic year". Clin Exp Optom. 88 (3): 153–9.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  35. ^ Online Books. Imagination Blindness.
  36. ^ Russell S. Worrall OD, Jacob Nevyas PhD, Stephen Barrett MD. "Eye-Related Quackery". Quackwatch. Retrieved 2007-02-12.{{cite web}}: CS1 maint: multiple names: authors list (link)
  37. ^ Janet Goodrich. Natural Vision Improvement. Greenhouse Publications, 1986. ISBN 0-89087-471-9

Free online books and articles by Bates

Sites critical of the Bates Method