Department of Ophthalmology, Faculty of Clinical Medicine Mannheim, University of Heidelberg, Mannheim, Germany. Jost.Jonas@augen.ma.uni-heidelberg.de

PURPOSE: To evaluate for which range of refractive error the optic disk size depends on, or is independent of, the refractive error. DESIGN: Clinical observational study. METHODS: The study included 1999 eyes of 1011 subjects with a mean refractive error of -0.97 +/- 2.72 diopters (range, -24.25 to +9.4 diopters). Optic disk photographs were morphometrically evaluated. RESULTS: The relation between optic disk area and refractive error showed a curvilinear shape, with a steep increase toward high myopia starting at -8 diopters, and a decrease toward high hyperopia starting at +4 diopters. CONCLUSION: The optic disk size depends on the refractive error with an increase in highly myopic eyes beyond -8 diopters and a decrease in highly hyperopic eyes beyond +4 diopters. Confirming histomorphometric studies, the limits of -8 diopters and +4 diopters may be discussed to refine the definitions of high hyperopia and high myopia.