title: Ethnic differences in optic nerve head topography.
abstract: OBJECTIVE
  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.
authors.affiliation: Department of Ophthalmology, University of California, San Diego, La Jolla, California, U.S.A.
authors.forename: C S
authors.initials: CS
authors.lastname: Tsai
authors.forename: L
authors.initials: L
authors.lastname: Zangwill
authors.forename: C
authors.initials: C
authors.lastname: Gonzalez
authors.forename: I
authors.initials: I
authors.lastname: Irak
authors.forename: V
authors.initials: V
authors.lastname: Garden
authors.forename: R
authors.initials: R
authors.lastname: Hoffman
authors.forename: R N
authors.initials: RN
authors.lastname: Weinreb