I've done a bit of research into Ortho-K. It certainly does produce short-term improvements in myopia, but at the expense of thinning of the central cornea. I haven't found what the implications of this thinning are. There haven't been too many proper scientific trials of Ortho-K, but the ones I found are:
The Berkeley Orthokeratology Study in the American Journal of Optometry & Physiological Optics. It's findings were that the refractive error fluctuated considerably during the period of follow-up and these fluctuations tended to be larger in those subjects who had shown greater changes in refractive error.
They concluded that it is possible to reduce myopia about 1D; however, the change is not permanent. Results indicate that the level of vision during periods of nonlens wear would be unstable, making it difficult to predict what the quality of vision would be under a retainer lens wear program. They concluded that orthokeratology produces modest reductions in myopia; however, the effect will not persist without continued lens wear and therefore is of limited clinical value in permanently reducing myopia.
An evaluation of orthokeratology in Ophthalmology, Vol 87, 729-744, Copyright © 1980 by American Academy of Ophthalmology found that analysis of the information in this study demonstrates that an OK procedure utilizes techniques of fitting that differ from standard contact lens techniques. The responses to OK are unpredictable and uncontrollable. The quality of uncorrected vision is worse than with contacts or glasses, and the chances of attaining 6/12 (20/40) uncorrected vision are small. Once lenses are removed, the corneal parameters return toward prefit levels.
Pinhole glasses have been used for a long time to evaluate eyes. Next time you are at the doctor, have a look at the black disc that they use to cover your eye while they test the other one. It usually has one or more pinholes in the other end. Looking through a pinhole will negate the effect of just about any refractive error, and therefore allow the doctor to determine whether a reduction in visual acuity is due to a refractive error or to some other eye pathology. It doesn't relax the eyes, it just allows relatively parallel light rays to reach the eye, and therefore removes the need for the eye to focus. It's the same as the greatly increased depth of focus that you get with an SLR camera when you use a small aperture setting(i.e. a large f number). So a pinhole will allow you to focus on objects, but obviously has no practical use because of the reduction in field of view, and the reduction of the amount of light reaching the eye.
If anyone can explain to me how the eye exercises work, I would love to know. The muscles which operate the lens of the eye, and therefore change the focal length of the system, are relaxed when looking at distant objects, and contract to focus on near objects. I can see how exercising these muscles may potentially improve near vision, but not distant vision. Myopia, or problems with distant vision, is usually a function of the shape of the cornea, or of the shape of the eyeball itself. That's how Ortho-K and laser refractive surgery works, by changing the shape of the cornea.
I'm very interested in this, so would welcome any feedback.
Cheers,
ausdoc