Abstract

Degradation of the retinal image for extended periods of time causes axial elongation and myopia ("deprivation myopia") in both animals and humans. In chickens, even little image degradation for short periods of time is sufficient to produce longer eyes and "deprivation myopia", given that no intermittant "normal" visual experience occurs. If chicks are kept in the dark for the remaining time, 3 hours of vision per day through frosted occluders is sufficient to produce deprivation myopia (Schwahn and Schaeffel, 1994). On the other hand, 30 minutes of intermittent normal vision reduce deprivation myopia down to 50% (e.g. Napper et al., 1995). There is plenty of evidence showing that the central pathways of accommodation have no major effect on induced refractive errors in animal models (e.g. Diether and Schaeffel, 1997), possibly with one exception (Wildsoet and Wallman, 1995). Therefore, in first approximation, one can restrict the analysis to a retinal mechanism.

© 1998 Optical Society of America