Early in life, at ages corresponding to the rapid infantile phase of ocular growth in humans, visual feedback can modulate refractive development in monkeys and many other species. To determine if vision-dependent mechanisms can still influence refractive development in primates during the slow juvenile phase of ocular growth, the time period when myopia typically develops in human children, we examined the effects of patterned visual deprivation on adolescent monkeys. The onset of visual deprivation was between 3.7 and 5 years of age, which corresponds to onset ages between about 15 and 20 years. The ocular effects of pattern deprivation were assessed by cycloplegic retinoscopy and A-scan ultrasonography. At the onset of pattern deprivation, all 4 monkeys were isometropic (equal refractive error in the left and right eyes) and the axial dimensions in the 2 eyes were well matched. Following 71 to 80 weeks of pattern deprivation, all of the visually deprived ey es had bec ome relatively more myopic than their fellow non-treated eyes and they exhibited relative increases in vitreous chamber depth and axial length. Therefore, we have now demonstrated that vision-dependent mechanisms can influence ocular growth and refractive development in "teenage" monkeys. These results raise the possibility that visual experience may be involved in the genesis of school-age myopia in children. FUNDING University of Houston $10,000 9/01/96 - 4/30/99 PUBLICATIONS Smith, EL III, Bradley, D.V., Fernandes, A. and Boothe, R.G. Form deprivation myopia in adolescent monkeys. Optom. Vis. Sci. (In press). P51RR00165-38 1/1/98 - 12/31/98 Yerkes Regional Primate Research Center