Hemi-Retinal Form Deprivation: Evidence for Local Control of Eye Growth and Refractiv

[ODwire.org NewsBot]

Hemi-Retinal Form Deprivation: Evidence for Local Control of Eye Growth and Refractive Development in Infant Monkeys. Invest Ophthalmol Vis Sci. 2009 Jun 3; Authors: Smith EL, Huang J, Hung LF, Blasdel TL, Humbird TL, Bockhorst KH PURPOSE. To determine whether refractive development in primates is mediated by local retinal mechanisms, we examined the effects of hemi-retinal form deprivation on ocular growth and the pattern of peripheral refractions in rhesus monkeys. METHODS. Beginning at about 3 weeks of age, 9 infant monkeys were reared wearing monocular diffuser lenses that eliminated form vision in the nasal field (nasal field diffusers, NFD). Control data were obtained from the non-treated fellow eyes, 24 normal monkeys, and 19 monkeys treated with full-field diffusers (FFD). Refractive development was assessed by retinoscopy performed along the pupillary axis and at eccentricities of 15, 30 and 45 deg. Central axial dimensions and eye shape were assessed by A-scan ultrasonography and magnetic resonance imaging (MRI), respectively. RESULTS. Hemi-retinal form deprivation altered refractive development in a regionally selective manner, typically producing myopia in the treated hemi-fields. In particular, 6 of the NFD monkeys exhibited substantial amounts (-1.81 to -9.00 D) of relative myopia in the nasal field that were most obvious at the 15 and 30 deg nasal field eccentricities. The other 3 NFD monkeys exhibited small amounts of relative hyperopia in the treated field. The alterations in peripheral refraction were associated with local, region-specific alterations in vitreous chamber depth in the treated hemi-retina. CONCLUSIONS. The effects of form deprivation on refractive development and eye growth in primates are mediated by mechanisms, presumably retinal, that integrate visual signals in a spatially restricted manner and exert their influence locally. PMID: 19494197 [PubMed - as supplied by publisher]

More...