Myopia is common among the students or persons particularly females who have a height less than 5 feet. Mostly its incidence is directly proportional with the shortness of height. We observed that it is less common among the taller students particularity in males who are generally taller than the females.
In most of these patients myopia gradually increase from --1 to --3, and even more within few years after starting to use concave lens.
Causes of this myopia and its deterioration may be due to at least two factors:
1. Students commonly use reading desk with same standard height in the school and at home. Students with short stature have to focus their eyes at a closer distance than taller students. To compensate this closer vision, optical power of the eyes begins to increase during early teenage period and these students become myopic.
2. During correction of myopia ophthalmologists prescribe negative lens usually for constant use. Although these concave lens are not needed for near vision, but due to constant use of the lens according to the physician’s advice, the optical power of the eyes increase gradually to compensate the concave lens and the student increasingly become more myopic. This is a vicious cycle. In this way myopia continues to increase at least during their studentship period. So use of reading desk at school and home with appropriate height of the students should prevent myopia and avoidance of concave lens used for distant vision or use of appropriate lens during closer vision will prevent further deterioration of the affected students or people.
Interesting model Tom, but where are the studies to support your assertion?
Undercorrection seems to accelerate progression.
Probably at young ages, overplusing the subject (I mean correcting more myopia than what he or she actually needs, e.g. because of measuring certain amount of accommodation as well) for long times may induce reemetropization (I mean growth of the eye ball to emmetropize the system spectacle + eye). This way you will progressively increase myopia by the use of minus lenses.
Minus lenses can increase myopia. But when the patient with myopia doesn't wear a glasses for near he/she can increase exo's phoria and trophia
Due to animal models and different studies as the COMET, some theories has raised about why using opthalmic concave lenses can aid in mypia progression during scholarship. It seems more related to a hyperopization of the peripheral retina rather than an increase on accomodation demand. Beyond genetics, it seems that exposure to sunlight acts as a protective factor against myopia. See the works by Donald Mutti and Kathryn A. Rose. I'd especially recomment you the work by Logan et al: Posterior Retinal Contour in Adult Human Anisomyopia Invest Ophthalmol Vis Sci. 2004;45:2152–2162) DOI:10.1167/iovs.03-0875.
Interesting model Tom, but where are the studies to support your assertion?
Undercorrection seems to accelerate progression.
Under correction does not accelerate progression of myopia, but the opposite, it slows it. Children with no correction had slower myopia rate of progression in this study:
Effect of uncorrection versus full correction on myopia progression in 12-year-old children. Graefe's Archive for Clinical and Experimental Ophthalmology. 2017, Volume 255, Issue 1, pp 189–195
which confirmed:
Medina A. A model for emmetropization : The effect of corrective lenses. Acta Ophthalmologica.1987; 65: 565-571, a study of 26 eyes concluding that "the use of corrective lenses changes the future refraction of the eye".
and:
The progression of corrected myopia. A. Medina. Graefe's Archive for Clinical and Experimental Ophthalmology. 2015, Volume 253, Issue 8, pp 1273–1277
https://dspace.mit.edu/handle/1721.1/105227
Negative lenses aggravate myopia while positive lenses can prevent it. Medina’s feedback theory predicts that correction of myopes makes their myopia progress linearly and that partial correction of hyperopia prevents myopia. See the results with patients at:
https://dspace.mit.edu/handle/1721.1/105227
https://link.springer.com/article/10.1007%2Fs10792-017-0493-7
There is a huge amount of data supporting association of myopia with more near work (so logically under-correction, rather than overcorrection should aggravate myopia). use of atropine to limit myopia progression also points in the same direction. Sample the studies: Nature 519, 276–278 (19 March 2015), Ophthalmology 2013;120:1080–1085 & Ophthalmol Vis Sci. 2012;53:7169–7175 (outdoor activity reduces myopia); Ophthalmology 2015;122:1489-1497 (higher education aggravates myopia), etc. There are also several recent meta-analyses and reviews. One (Lancet 2012; 379: 1739–48) points that it's the peripheral hyperopic focus in high myopia which may contribute to myopia progression; but even this was a short term effect. So I'm afraid both of your beliefs about myopia progression (short stature and constant use of myopic glasses may be speculative).
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