DIFFUSER CONTACT-LENSES RETARD AXIAL ELONGATION IN INFANT RHESUS-MONKEYS

In each of five monkeys, one eye was fitted with a diffuser lens at bi rth. This lens allowed pattern vision, but also reduced contrast by ab out 1 log unit. In four out of five monkeys, the treated eyes were sho rter and more hyperopic than the untreated fellow eyes. At 25 weeks of age, interocular differences (OD-OS) of the experimental group were s ignificantly greater than interocular differences of age-matched norma l monkeys for both axial length (P < 0.05) and refractive error (P < 0 .02). In addition, while the treated eyes were significantly different from normal eyes for both axial length measurements (P < 0.01) and re fractive error (P < 0.01), there were no significant differences betwe en the untreated fellow eyes and normal eyes. In primates less severe pattern deprivation appears to produce an effect on eye growth that is opposite to that of severe pattern deprivation (little or no pattern vision), which typically results in axial myopia.