The Bates method, elixirs, potions and other cures for myopia: how do they work?

Studies have documented a very high prevalence of myopia among urbanized Asian countries over recent decades,1 reaching epidemic levels of around 70–80% of young adults living in East Asian countries such as Taiwan, Japan, Hong Kong and Singapore.2 Prevalence levels are typically lower in young Western adults at around 15–30%, but remain significant.1 Although myopia can be relatively easily corrected with spectacles, contact lenses or refractive surgery, all can have some negative effects on quality of life in younger patients in terms of perceived appearance and convenience (spectacles, especially higher-powered spectacles), convenience (contact lenses) and significant symptoms and functional impairment for those with complications from refractive surgery.3 In addition, high myopia is associated with a variety of abnormal conditions, including lacquer cracks, posterior staphyloma, chorioretinal atrophy, choroidal neovascularisation, macular atrophy, retinal detachment, cataracts, glaucoma and poorer visual acuity.4, 5 It is therefore not surprising that there are large numbers of available treatments. Those treatments that have been appropriately assessed to date have shown limited effectiveness in slowing the progression of myopia6-8 and many of the myopia 'cures' available on the internet (these include vitamins, fish oils, essential oils and herbs9) have not been assessed. Could some of these alternative therapies work, and if so, how? One of the most commonly used alternative therapies is the Bates method, developed by the New York ophthalmologist William Horatio Bates (1860–1931).10 This is still promoted in many books, including the original best-seller 'Perfect sight without Glasses' (1920) or copies, plus recent translations in both Chinese and Spanish, The American Vision Institute's 'Improve your vision without glasses or contact lenses'11 and Barnes' Improve Your Eyesight: A Guide to the Bates Method for Better Eyesight Without Glasses12 amongst others.13 It also seems to be promoted by some behavioral optometrists and vision therapists.10, 11 Bates attributed nearly all sight problems to habitual strain of the eyes and felt that glasses were harmful. Many people have reported anecdotal improvements in their vision with the techniques (take a look at the comments left by readers of the various books on Amazon websites), most famously the author Aldous Huxley (1894–1963).10 The Bates method includes palming, visualization, movement (or 'shifting') and sunning. None of these techniques appear to have any plausible rationale for treating myopia.14 For example, although increased time spent outdoors appears to reduce myopia progression,1 Bates' 'sunning' originally involved looking directly at the sun (now well known to cause solar retinopathy15) although he later changed that advice to allowing direct sunlight onto the 'white of the eye' subsequent to sunlight exposure to closed eyelids and later books omit this part of the method.10 'Palming' involves covering the closed eyes with the palms of the hands, without putting pressure on the eye, which he claimed would help the eyes relax.10-13 Hopefully no pressure would be exerted by the palms as short-term mechanical pressure on the eye can increase intra-ocular pressure, leading to transient increases in axial length and myopia.16 This begs the question of what is the cause of the improvements in vision reported by people who use these methods? It could be partly due to the placebo effect, in that randomized controlled trials have shown significant improvements in visual acuity and symptoms with placebo 'treatments' of glasses with no power17 or 'sugar pills'.9 Given that the placebo effect appears to be greater the more dramatic the treatment (four placebo sugar pills a day are more effective than two for eradicating gastric ulcers, salt water injections are a more effective treatment for pain than sugar pills),18 perhaps the regimen proposing the largest array of strenuous eye exercises would provide the largest placebo effect. Part of any improvement may be simply memorisation, in that most of the Bates method books include a Snellen letter chart for readers to monitor their visual acuity and with repetitive measurements, some learning of the subset of letters is likely.19, 20 However, the most likely causes of improvements in vision are blur adaptation21-26 (in the short-term) and perceptual learning27-30 (in the longer term and if demanding visual tasks are involved in the treatment). Both of these topics are discussed in articles in this issue of OPO by Sotiris Plainis and colleagues of the University of Crete.26, 30 It is now well known that with sudden blur (such as when taking off myopic glasses or when blur lenses are added in research experiments), the visual system will adapt to improve visual acuity,21-26 likely by increasing the gain of high spatial frequency channels and decreasing the gain of low frequency channels.23 Improvements of more than two lines of acuity have been reported22, 24, 26 and these are typically greater in myopes22, 26 and possibly greatest in high myopes.26 However, blur adaptation seems short-lasting (the time course of the condition is as yet unclear) and long-term improvements may be more likely using perceptual learning (which may trigger and/or enhance the process of blur adaptation)29 which has been shown to lead to improvements in distance visual acuity in adult amblyopes27, 28 and in the 'good eye' of patients with severe impairment in the other eye30 and improvements in near visual acuity to a level where reading glasses were not necessary in early presbyopes.29 The suggestion is that perceptual learning (repeated practice on a demanding visual task) can increase the efficiency of neural processing in order to perform 'de-blurring' of blurred images and retrieve the information for further processing.29 Given that the Bates method emphasizes repeated relaxation of the eyes, rather than repeated practice on a demanding task, it seems likely that its positive effects are dominated by blur adaptation plus the placebo effect and memorisation rather than perceptual learning. What clinical implications do these findings have? In the short-term, optometrists should certainly be well aware of blur adaptation, perceptual learning and the placebo effect and understand what effects they could have on their patients' vision and be able to answer any questions about the efficacy of alternative treatments for ametropia in an informed manner. In the longer term, there seem to be a plethora of questions to answer: what is the time course for blur adaptation? Does blur adaptation give some low myopes sufficiently good vision (there appears to be significant variation in the amount of blur adaptation individual patients have25; plus blur tolerance also seem to be variable between individuals and linked to personality type31) in most situations? It is possible that the reason some adult-onset low myopes tend to get glasses for driving and particularly night driving, despite reporting good vision for other tasks, might be that in the night driving situation decreasing the gain of low frequency selective channels to allow an increase in the gain of high spatial frequency channels (i.e. blur adaptation23) is not effective in improving overall vision of a low luminance, low contrast scene. The effect of blur adaptation on new part-time myopic glasses wearers should also be considered. Will their vision be poorer when they take their new spectacles off than their 'unaided' vision before they got the glasses? Might this make them think that the glasses had 'made their eyes worse'? What advice should be given to them? Should blur adaptation and its effects be explained? Could low myopes cope without glasses given perceptual learning? Should we be using perceptual learning techniques to improve visual acuity in myopes, absolute hyperopes, astigmats and presbyopes as well as amblyopes and others? Myopia and its treatment are a hot topic at the moment and are likely to be so for many years given its high prevalence and currently limited treatment (as opposed to correction) options. I am therefore delighted to report that one of the next issues of OPO will be a feature issue entitled 'Understanding and controlling myopia – where we are now', which is a compilation to honour the research achievements and mark the passing of Josh Wallman and will be led by feature issue editors Christine Wildsoet, Debora Nickla, Jeremy Guggenheim and Nicola Logan. It promises to be a landmark issue.