Ethnic differences in optic nerve head topography.

Purpose: To investigate ethnic differences in optic nerve head topography.

Methods: This is a cross-sectional university-based comparative study of 180 normal subjects (43 African-American, 45 Asian, 48 Hispanic, and 44 white subjects) ages 19-40 years. Optic nerve head parameters including optic disc size, cup-disc ratio, rim area, rim volume, cup volume, and maximal cup depth were measured using a confocal scanning laser ophthalmoscope (Heidelberg Retina Tomograph). Differences among groups were evaluated using analysis of variance.

Results: Disc area, cup volume, maximal cup depth, and vertical cup-disc ratio were largest in African-Americans, intermediate in Asians and Hispanics, and smallest in whites; for these parameters the differences between African-Americans and whites were statistically significant. Significant differences were also found between African-Americans and Hispanics for cup volume, and between African-Americans and Asians for vertical cup-disc ratio and maximal cup depth. Rim volume and rim area were not significantly different among the four ethnic groups.

Conclusions: Ethnic differences in the normal optic nerve are present and should be taken into a ccount when evaluating the optic disc for glaucoma and other optic neuropathies.