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PE Foeller, DV Bradley, AM F Wong, L Tychsen; Early Versus Delayed Repair Of Infantile Strabismus In Macaque Monkeys: Effects On Cerebral Ocular Motor Circuits . Invest. Ophthalmol. Vis. Sci. 2002;43(13):216.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: The purpose of the study was to determine how early vs. late repair of strabismus influences the development of ocular motor behavior and brain pathways in primates. Methods: Infant macaques were fitted with goggles on day 1 of life. The early repair group (2 experimental and 1 control) wore the goggles for a period of 3 wks (the equivalent of 3 mos in humans). The delayed repair groups (4 experimental and 2 control) wore the goggles for a period of 3 mos or 6 mos (the equivalent of 12-24 mos in humans). The experimental animals wore prism goggles to induce optical strabismus of 11.4 - 22.8 deg while the control animals wore goggles with plano lenses. At age 1 year, the monkeys were trained to perform visual fixation and tracking tasks, and eye movements were recorded using search coils. After eye movement recording, neuroanatomic tracers were injected and the cerebral cortex was sectioned and analyzed. Results: The early repair monkeys regained normal eye alignment and showed stable fixation as well as robust short latency fusional (disparity) vergence eye movements. Monocular horizontal smooth pursuit and large field OKN movements were symmetric. In contrast, the delayed repair monkeys showed persistent heterotropias, subnormal or absent fusional vergence, pursuit/OKN asymmetry, latent nystagmus, and DVD. The ocular motor deficits correlated with abnormalities in binocular connections between ocular dominance columns within layers 2-4 of the striate cortex. Conclusion: Early repair of strabismus in primates prevents the constellation of ocular motor defects that typify infantile esotropia. The ocular motor abnormalities in late repair cases appear to be due primarily to connectivity defects within specific area V1 cortical laminae.
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