Continuous ambient lighting and lens compensation in XXXX monkeys.

@entity1 @entity2516 @entity9340 @entity735 @entity2608
PURPOSE: Protracted daily lighting cycles do not promote @entity735 in @entity1 monkeys as they do in a variety of avian species. However, observations in @entity1 suggest that ambient lighting at night may reduce the efficiency of the emmetropization process in primates. To test this idea, we investigated the ability of @entity1 monkeys reared with continuous light to compensate for optically imposed changes in @entity2516 . METHODS: Beginning at about 3 weeks of age, a hyperopic or myopic @entity9340 was imposed on 12 @entity1 @entity2608 by securing either a -3 D or +3 D lenses in front of one eye and a zero-powered lens in front of the fellow eye. Six of these monkeys were reared with the normal vivarium lights on continuously, whereas the other six lens-reared monkeys were maintained on a 12-h-light/12-h-dark lighting cycle. The ocular effects of the lens-rearing procedures were assessed periodically during the treatment period by cycloplegic retinoscopy, keratometry, and A-scan ultrasonography. RESULTS: Five of six animals in each of the lighting groups demonstrated clear evidence for compensating anisometropic growth. In both lighting groups, eyes that experienced optically imposed hyperopic defocus (-3 D lenses) exhibited faster axial growth rates and became more myopic than their fellow eyes. In contrast, eyes treated with +3 D lenses showed relatively slower axial growth rates and developed more @entity2516 . The average amount of compensating @entity9340 (continuous light, 1.6 +/- 0.5 D vs. control, 2.3 +/- 0.5 D), the structural basis for the @entity2516 , and the ability to recover from the induced @entity2516 were also not altered by continuous light exposure. CONCLUSION: Ambient lighting at night does not appear to overtly compromise the functional integrity of the vision-dependent mechanisms that regulate emmetropization in higher primates.
