The role of optical defocus in regulating refractive development in infantmonkeys

Early in life, the two eyes of infant primates normally grow in a coordinat ed manner toward the ideal refractive state. We investigated the extent to which lens-induced changes in the effective focus of the eye affected refra ctive development in infant rhesus monkeys. The main finding was that spect acle lenses could predictably alter the growth of one or both eyes resultin g in appropriate compensating refractive changes in both the hyperopic and myopic directions. Although the effective operating range of the emmetropiz ation process in young monkeys is somewhat limited, the results demonstrate that emmetropization in this higher primate, as in a number of other speci es, is an active process that is regulated by optical defocus associated wi th the eye's effective refractive state. (C) 1999 Elsevier Science Ltd. All Fights reserved.