Development of optical quality in the infant monkey (Macaca nemestrina) eye.

Behavioral measures of the development of spatial vision, such as contrast sensitivity and acuity, do not distinguish between optical and neural contributions to the emergence of adult visual sensitivity in primates. The optical contribution to visual development in monkeys was estimated by measuring retinal image quality in the eyes of seven infant monkeys ranging in age from 2 days to 9 months. Results from both longitudinally and cross-sectionally tested monkeys indicate that the optics in infant monkeys are good at birth but that improvements with age can be found. The optical modulation transfer function shows that contrast transmission through the optics increases with age at all measurable spatial frequencies. Adult levels of optical quality are seen by 13 weeks of age. In comparison to the large improvements found during development in contrast sensitivity in monkeys. the optical changes are small and probably pose no major limit to the development of spatial vision in this species.