Optic disc size smallest in white-American glaucoma, suspect patients, study finds

J Glaucoma. 2009;18(8):595-600.

The mean optic disc size of a population of white-American glaucoma and glaucoma suspect patients was significantly smaller than the optic disc measurements of African-, Asian-, Hispanic- and Filipino-American patients, a study found.

"In our glaucoma clinic-based population, white-Americans had smaller optic discs than all other races, and there were no optic disc size differences among the other races studied," the authors said. "Optic disc size had no significant relationship to age, sex, [central corneal thickness], cylindrical refraction or diagnosis and a small direct relationship to [spherical equivalent refraction]."

The study looked at 576 eyes of 319 patients who had received Heidelberg Retina Tomograph 2. Of those eyes, 215 were white; 178 were Asian, non-Filipino; 67 were African; 66 were Hispanic; and 50 were Filipino. Correlation between optic disc size and race, age, sex, diagnosis, central corneal thickness, spherical equivalent refraction and cylindrical refraction were measured with multivariate regression analysis.

The study found that the mean optic disc size of white-Americans was 2.15 mm²; in African patients, it was 2.55 mm²; in Asian patients, 2.38 mm²; in Filipino patients, 2.48 mm²; and in Hispanic patients, 2.57 mm² (P = .0007).

"Our results suggest that optic disc size may vary with race, implying that our reliance on clinical cup-to-disc ratio may be of particular importance ethnically," the researchers said. "White-Americans in our population, because of their smaller disk sizes, are likely to manifest smaller cup-to-disc ratios for a given amount of neuroretinal rim area than other races."