From Walter Kaplan
J. R. Scott (Letters, 10 June) protests against Jonathan Beard’s suggestion that close work can contribute to the development of myopia (This Week, 13 May), leans on genetic predisposition as the cause of myopia, aided by a growth spurt at puberty and a deficiency of protein in the diet.
Apparently, Scott is not familiar with Francis A. Young’s 1969 study of “The Transmission of Refractive Errors Within Eskimo Families” (American Journal of Optometry and Archives of the American Academy of Optometry, vol 46, p 676).
Young found “virtually no myopia among grandparents and parents” who had had, in most cases, no more than six years of ungraded schooling (and all whom had been through puberty). He found “approximately 58 per cent of the offspring … myopic”, the offspring having “had typical American-style schooling” which covers grades 1 to 12, with much close work. The youngsters were eating the typical Eskimo diet of caribou, whale and other mammal foods, ruling out the protein deficiency Scott felt was a factor.
I believe the high and significant correlations Young found between siblings allows for a possible genetic predisposition as Scott suggests, but that the almost zero myopia correlation between parent and child suggests that environmental factors are needed to make that genetic predisposition for myopia manifest itself as measurable myopia.
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Other studies by Young, and by others, as well as the clinical experience of many optometrists, support the idea that judiciously selected convex lenses can have a slowing or braking effect on the development of myopia. There are other therapy methods used by many optometrists to improve visual efficiency which seem also to slow the development of myopia.
