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11. Effects of optical defocus and spatial contrast on anterior chamber depth in chicks

Author

Barutchu, A, Crewther, S, and Crewther, D

Subjects
genetic structures, sense organs, eye diseases
Abstract

The goal of this study was to investigate the effect of optical defocus and spatial contrast on refractive development and, in particular,on anterior chamber growth. Ninety chicks were raised from day 4-10 post-hatching wearing monocular lenses (+/-10 Dor 0 D), in an environment with either high, low or no spatial contrast patterns: 30%, 6% or 0% contrast, respectively. At day 10, the chicks' refractive state and ocular components were assessed using retinoscopy and A-scan ultrasonography. Ocular defocus resulted in sign-dependent significant differences in refractive error, axial length and vitreous chamber depth. Lens wear also led to significant spatial contrast dependent changes in anterior chamber depth. Varying ambient spatial contrast in the chick's environment did not inhibit emmetropization processes; however, anterior chamber growth was particularly susceptible to changes in spatial contrast.

Published
2002

20. THE CAT AS A MODEL FOR VISUAL DEPRIVATION.

Author

CLELAND, B. G., CREWTHER, S. G., and CREWTHER, D. P.

Abstract

Both behavioural and neurophysiological changes can be observed in cats that have experienced interference with their normal visual environment. This visual deprivation may result from alterations to the path of light forming the normal image on the retina, and includes changes that cause the image to fall on an inappropriate part of the retina so that normal binocular interactions are affected. While some neurophysiological changes can be observed at the level of the lateral geniculate nucleus they become more prominent as information reaches the visual cortex, where cells commonly receive neural excitation from both eyes and require the information to come from corresponding parts of the two retinas and that the stimulus should have appropriate orientation and direction of movement. Many of the observations of deprivation in animals have clear parallels in the human environment. [ABSTRACT FROM AUTHOR]

Published
1985
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