Do Glasses Make Your Vision Worse?
Commission on Behavioral and Social Sciences and Education 1989. Myopia: Prevalence and Progression http://books.nap.edu/openbook.php?isbn=0309040817&page=21
Morgan and Rose 2005 "How genetic is school myopia?" http://www.ncbi.nlm.nih.gov/pubmed/15555525
Rose, Morgan et al 2008 "Outdoor activity reduces the prevalence of myopia in children" http://www.ncbi.nlm.nih.gov/pubmed/18294691
Theodore Grosvenor 2003 "Why is there an epidemic of myopia" http://www.optometrists.asn.au/ceo/backissues/vol86/no5/2312
Garner et al 1999 "Prevalence of myopia in Sherpa and Tibetan children in Nepal" http://www.ncbi.nlm.nih.gov/pubmed/10375242
Thorn et al 2005 "Refractive status of indigenous people in the northwestern Amazon region of Brazil" http://www.optvissci.com/pt/re/ovs/abstract.00006324-200504000-00011.htm
2. Negative-diopter, or "minus" lenses are prescribed as corrective lenses to give clear distant vision to nearsighted people. They work by transforming distant images to images that can be seen clearly by an eye that is adjusted for the near point. Through minus lenses, the eye must focus closer in order to see objects clearly at any distance. They make midrange work require near focusing, and make near work require intensively near focusing. Thus, while initially alleviating the symptoms, the minus lenses prescribed as corrective lenses for myopia intensify one the risk factors for myopia.
Reference: any optics textbook
3. Full-time wear of minus lenses makes normal-sighted animals myopic.
Hung/Crawford/Smith 1995 "Spectacle lenses alter eye growth and the refractive status of young monkeys." http://www.ncbi.nlm.nih.gov/pubmed/7585177
Zhu/Winawer/Wallman 2003 "Potency of Myopic Defocus in Spectacle Lens Compensation" http://www.iovs.org/cgi/content/abstract/44/7/2818
Norton et al 2006 "Effectiveness of Hyperopic Defocus, Minimal Defocus, or Myopic Defocus in Competition with a Myopiagenic Stimulus in Tree Shrew Eyes" http://www.iovs.org/cgi/content/abstract/47/11/4687
Kee et al 2007 "Temporal Constraints on Experimental Emmetropization in Infant Monkeys" http://www.iovs.org/cgi/content/abstract/48/3/957
Shen & Sivak 2007 "Eyes of a lower vertebrate are susceptible to the visual environment." http://www.ncbi.nlm.nih.gov/pubmed/17898310
4. Full-time wear of minus lenses prevents recovery in myopic animals that would otherwise recover.
McBrien et al. 1999 "Optical correction of induced axial myopia in the tree shrew: implications for emmetropization."
Wildsoet & Schmidt 2000 "Optical correction of form deprivation myopia inhibits refractive recovery in chick eyes with intact or sectioned optic nerves." http://www.ncbi.nlm.nih.gov/pubmed/11008143
5. The effect of "corrective" minus leans wear on animals who become myopic in their normal environment (e.g. caged animals, house dogs) has not been tested.
"Negative evidence" is hard to come by. However, here are two articles on naturally myopic dogs:
Myopia and refractive error in dogs (Murphy, Zadnik, and Mannis 1992) http://www.iovs.org/cgi/content/abstract/33/8/2459
Naturally occurring vitreous chamber-based myopia in the Labrador retriever (Mutti & Zadnik 2005) http://www.iovs.org/cgi/content/abstract/40/7/1577
If there had been an experiment correcting naturally myopic animals, it surely would have shown up under the "Similar articles in PubMed" link. No such article can be found. It is also telling that neither paper explicitly mentions the prospect of correcting the myopic dogs to determine the effect of correction on myopia. Contacting the authors of these papers confirmed that no follow-up studies putting corrective lenses on spontaneously myopic dogs had been performed or were planned.
6. The above considerations strongly suggest that corrective lenses for myopia, particularly in children, will cause myopia to increase: unaided distance vision will get worse, dependence on eyeglasses will increase, and a stronger prescription will be required for perfectly clear distance vision. However, the precise effect that corrective lenses have on the course of myopia has not been tested. In studies of children using who wear corrective lenses, the amount of myopia has been found to increase for a period of years as the strength of the lenses are increased. Some modifications of the standard prescription have been tested, including a slightly lowered prescription, or spectacles with a weaker-powered area in the bottom half to be used for reading (bifocals). In randomized clinical studies involving such glasses, the course of myopia has been found to be approximately the same as with normal glasses. This does not mean that minus lenses do not cause increased myopia. Even a less than full prescription amounts to an increase in "minus" power at all distances, and in the case of bifocals, the minus lens segment, though intended for distance viewing, can be used for midrange and near work as well. In the one peer-reviewed study that actually compared those who did not wear glasses at all with those who wore them as normally prescribed, the full time minus lens wearers had an increase in their myopia twice as much as those who never wore their glasses. Unfortunately the experiment was retrospective in design and the sample size was too small to permit a firm conclusion.
Wildsoet 1997 "Active emmetropization--evidence for its existence and ramifications for clinical practice." http://www.ncbi.nlm.nih.gov/pubmed/9390372
Extrapolation of these findings to humans predicts that ... refractive correction of myopia will lead to accelerated progression.
Ong et al 1999 "Effects of spectacle intervention on the progression of myopia in children." http://www.ncbi.nlm.nih.gov/pubmed/10416930
the nonwearers exhibited an age-adjusted 3-year progression approximately one-half that of the full-time wearers.... Further investigation using a larger sample is warranted.
Wallman & Winawer 2004 "Homeostasis of Eye Growth and the Question of Myopia" http://www.neuron.org/content/article/fulltext?uid=PIIS0896627304004933
Related to this, there has been a view, which has existed on the margins of science for decades, that most myopia is iatrogenic, in that the eye doctor, instead of letting the myopia stabilize at the level that brings the page into focus, corrects the vision with negative lenses, which reimposes the original error that caused the myopia in the first place. Needless to say, this idea has not been explicitly tested, as that would require randomly assigning some myopic children to be uncorrected, a procedure unlikely to be tolerated by parents or institutional review boards.Back to library...