Intraocular pressure, Goldmann applanation tension, corneal thickness, and corneal curvature in Caucasians, Asians, Hispanics, and African Americans

PURPOSE: This is to investigate whether there are differences in Goldmann applanation tonometry (GAT), central corneal thickness, and corneal curvature among four racial groups. If differences are present, they may alter GAT reading, diagnosis, and management of glaucoma in the population. DESIGN: Observational retrospective cross-sectional study. METHODS: Charts of patients who have had keratorefractive surgery were examined. Central corneal thickness, corneal curvature, refractive power, and GAT were measured in 1,482 Caucasian, 172 Asian, 204 Hispanic, and 118 African,American eyes (total 1,976 eyes). Refractive components and GAT were compared. We compared intraocular pressure (IOP) adjusted by GAT, central corneal thickness, and corneal curvature among the four groups. RESULTS: There was a statistically significant difference between the mean (+/- standard deviation) central corneal thickness of African American (535.46 +/- 33.39) and Caucasian (552.59 +/- 34.48) eyes. Mean central corneal thickness was near 550 mum in Caucasians, Asians, and Hispanics. No significant difference was noted in corneal curvature in the four groups. There was a significant correlation between central corneal thickness and corneal curvature, and GAT was similar among the four groups. When IOP was adjusted for central corneal thickness, it was significantly greater in African Americans (16.12 +/- 3.27) than in Caucasians (14.32 +/- 2.93). Corneas of women were significantly thinner than corneas of men. CONCLUSIONS: African Americans had significantly thinner central corneal thickness than Caucasians, Asians, or Hispanics, causing the underreading of true IOP. Significant correlation between central corneal thickness and corneal curvature was demonstrated. Uncorrected GAT underreading of African Americans may lead to delay in diagnosis, inadequate treatment target setting, and higher morbidity. Goldmann applanation tonometry needs to be corrected by central corneal thickness and corneal curvature for proper diagnosis and management of glaucoma. (C) 2003 by Elsevier Inc. All rights reserved.