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J. Huang, L.-F. Hung, R. Ramamirtham, Y. Qiao-Grider, E. Smith III; Effects of Form Deprivation on the Pattern of Peripheral Refractive Errors in Infant Rhesus Monkeys. Invest. Ophthalmol. Vis. Sci. 2007;48(13):1033. doi: https://doi.org/.
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Myopic human eyes typically exhibit relative hyperopic refractive errors in the periphery. To determine if vision-induced axial elongation can produce both central myopia and relative peripheral hyperopia, we investigated the effects of form deprivation on peripheral refractive errors in developing monkeys.
Monocular form-deprivation was produced in 10 rhesus monkeys by securing diffuser lenses in front of the treated eyes at 3 weeks of age. To examine the role of central vision in the resulting refractive changes, the fovea and most of the perifovea (the central 10-12 degrees of the retina) of the treated eye was also ablated with an argon laser in 8 of these monkeys at the start of the lens-rearing period. Each eye’s refractive status was measured by retinoscopy along the pupillary axis and at 15 degree intervals along the horizontal meridian out to 45 degree eccentricities. Control data were obtained from 5 normal monkeys and 5 monkeys that had monocular foveal ablation and were allowed unrestricted vision.
At ages corresponding to the end of the lens-rearing treatment (about 150 days of age), normal monkeys exhibited a low degree of hyperopia in the central retina and small degrees of relative myopia in the periphery; the pattern of peripheral refractive errors was well-matched in the two eyes. Monocular foveal ablation, by itself, did not alter either central or peripheral refractive development. On the other hand, monocular form deprivation, either with or without foveal ablation, altered central as well as peripheral refractive development. Specifically, eight of the 10 form-deprived eyes exhibited more myopic/less hyperopic central refractive errors than their fellow non-treated eyes. Moreover, the eyes with relative central myopia also showed relative peripheral hyperopia and the degree of relative peripheral hyperopia increased with the degree of relative central myopia.
In addition to producing central axial myopia, form deprivation can alter the pattern of peripheral refraction producing relative peripheral hyperopia. Thus, both central and peripheral refractive errors are influenced by visual experience in primates. However, visual signals from the fovea are not essential for either of these vision-dependent changes.
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