Clinical investigation of the cup/disc ratio

1,277 white and 387 black male veterans were studied in an attempt to determine the racial difference, if any, between the distribution of cup/disc ratios in these two groups of non-glaucomatous patients. The data show a highly significant statistical difference between white and black patients in regard to normal variation of their C/D ratios. Although there were no differences between the prevalence of C/D ratios of 0.3 and less, there were important differences in the prevalence of ratios of 0.5 and greater. Blacks had C/D ratios of 0.5 and greater at almost five times the frequency of whites.