Multiple Pinhole Glasses
Pinhole glasses are definitely a useful tool for Vision Education: they are equally definitely not a substitute for it. They are not an instant panacea, but used with intelligence and imagination will certainly aid in the quest for better vision. These notes have been compiled, and are now included here in an updated form in response to many requests for information on this subject.
Multiple pinhole 'glasses' have been in use for about thirty-five years. Slightly different versions have appeared on the market at various and sometimes excessive prices. The more expensive ones are generally better made and finished but there is no clear evidence as to whether the optical qualities are any different. Various claims have been made for their efficiency both as a visual aid, and as a means of improving unaided eyesight. Manufacturers often refer to the Bates Method in their promotional material and some have taken to supplying Dr Bates' book together with their product.
The general consensus among Bates teachers is that these devices are useful but that the claims sometimes made for them as a complete solution to visual problems, or as a replacement for, or improvement on, the Bates Method are exaggerated and misguided. The remainder of this article describes how they work and makes some suggestions for their use.
When an object is viewed through a very small aperture (a pinhole) a clear image will always be formed because only coherent rays of light are able to pass through, so that the 'blur circle' normally formed by an out of focus eye is reduced almost to the clear point that would be seen if it were in focus. This means that, provided there is no opacity of the eye or impairment of the retina, the object will appear clear regardless of any refractive error. The image through a single pinhole is very small and dim, but by using a regular array of similar sized holes it is possible to enlarge the field of vision and improve the overall brightness of the image while still retaining most of the clarity of at least the central area.
In practice, the holes are of course rather larger than an ideal pinhole (which would be infinitesimally small!) and the size of hole is a compromise between clarity of resolution and brightness of illumination. Similarly, in theory the lens material should be infinitesimally thin (and at the same time perfectly opaque); in practice most versions are rather thick so that the light travels through a 'tunnel' with rather unpredictable optical results.
The initial experience for many people is of a form of 'insect vision', with distinct but multiple images overlapping in rather a confusing way. Every movement gives rise to a pronounced flicker which many people find quite disturbing at first. Some complain of increased strain and headaches at first use. This indicates that some manufacturers' claims that the eyes 'automatically' relax when using these things are a touch over-enthusiastic. Rather, as with so many other beneficial things, you have to find out how to relax in order to be able to use them, which some find easier than others. The flicker of movement must be just accepted - the Bates Method has a lot to say about the experience of visual movement - and after a while it becomes possible to find a way of centralising a particular object so as to eliminate the multiple images, at least from the central area. When this can be done the central object becomes noticeably clearer than its surroundings which is a useful demonstration of Dr Bates' principle of central fixation.
Advantages for Vision
According to Dr Bates, wearing glasses adds to the strain which underlies poor vision: however, until one learns more relaxed ways of using the eyes simply taking glasses off can also make matters worse. Since when wearing pinhole specs the dioptrics of the eye are irrelevant, it follows that at the very least one can be freed from the need to conform to the pattern of strain for which the glasses were fitted, while enjoying vision sufficiently clear to largely eliminate the urge to strain to see better. This does not in itself promote improvement, but by reducing the 'need' to strain and the time spent wearing glasses, increases the chances of success by other means.
It is fundamental to the Bates approach that vision is a constant learning process based on the feedback of information between eyes and brain. The traditional Bates practices are designed both to increase the sense of contact with what is seen and the awareness of variations in vision. This line of thought is developed further by at least one manufacturing company who design their holes to limit rather than eliminate the 'blur circle'. The idea is that, at the worst, the vision is good enough to make it easy to maintain relaxed interest and to improve the basic flow of information, but that it is possible for improved function to bring about noticeable improvement so that there is also a flow of feedback about the behaviour of the eye (which would not be so with true pinholes): in this way the eyes are constantly encouraged and good behaviour is rewarded. This idea is certainly plausible and broadly in agreement with Dr. Bates' principles. It can perhaps be developed yet further by the use of a modular kit incorporating different sizes of hole and grid spacing for different purposes: small holes to maximise the vision: larger ones to emphasise the learning curve, and a small to medium size for general purposes, perhaps.
The multiple array encourages two important aspects of normal visual behaviour, shifting and centralisation. In turn it is found that these can only be achieved if the use of the eyes is basically relaxed, so palming before use and attention to the principle of relaxation during use are recommended.
In general the use of pinhole glasses is two fold: as a developmental tool in vision improvement, and as a straightforward substitute for glasses in certain situations.
They can be freely used as a substitute for glasses in any situation where they are found to give adequate vision, although not for driving or any other potentially hazardous activity. Generally they will be easier to use in good light than poor. If it possible to use them for visually static tasks like TV and computer use they are much preferable to glasses since they encourage more mobility in the eyes, but not everyone finds this feasible.
In Bates or other vision improvement work it may be very good to try various practices, such as swings and chart exercises, alternately using the pinholes and unaided, rather than using the pinholes exclusively. It has been found, by myself and others, that relaxed 'central fixation' practice with a test card using rather large holes is followed by a definite improvement in the unaided acuity. As well as using the glasses in the conventional way, a sheet of the mesh, or similar material can be used as a multi-directional shifter, to hold in front of the eyes and move rapidly in all directions while looking through: this has a very powerfully stimulating effect on the saccades. This has been confirmed by a leading manufacturer of perforated plastics who has experience of staff operating machines which produce perforated plastic complaining of strain and dizziness from watching the material roll by, but also finding subsequently that their vision is improved!
One possible drawback of the multiple pinhole array is that it will often be impossible for the two central sightlines of a pcrson's cycs to be perfectly aligned on a single object through two corresponding holes. This makes it impossible to have normal binocular vision with normal convergence and probably accounts for many of the experiences of strain and headache reported by a few users. Many versions of the 'glasses', however, come with removable lenses and this can be very helpful. If one of the lenses is removed, the relatively clear vision from the 'pinholed' eye can be integrated with the unobstructed field of the other, avoiding the convergence problem and giving rather good vision overall. If this is done for short periods alternating the eyes it may also encourage better vision in the unassisted one. Work with alternate single eyes is used a great deal in the Bates Method, commonly using 'patching glasses' with a blacked-out 'lens'. This can be enhanced by having one eye blacked out and the other 'pinholed'.