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

https://doi.org/10.1016/S0002-9394(03)00424-0Get rights and content

Abstract

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 μm 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.

Section snippets

Design

This was a retrospective cross-sectional observational study.

Methods

Charts of 2,479 eyes of consecutive patients undergoing presurgical examinations for refractive surgery without ocular pathology between July 1999 and June 2002 at a multisurgeon refractive surgery center (Laser One, Inc.) in New York City were reviewed retrospectively. Pertinent information was transcribed into the computer database.

A total of 1,976 eyes were studied, of which 1,482 Caucasian (74.86%), 172 Asian (8.68%), 118 African-American (5.96%), and 204 Hispanic eyes (10.45%) had central

Results

The mean age of the population was 37.36 ± 9.71 years. The breakdown of age by ethnic groups is shown in Table 1.

Age and GAT do not appear to be related in this sample population (Figure 1). Regression between age (X) and GAT (Y) yielded: Y = 14.307 + 0.016* X; R^2 = 0.004. Correlations coefficient: 0.06; P = 0.063. This may be a reflection of the relative youth of the population studied.

Mean GAT by total population and the four ethnic groups (Table 2) were not significantly different. Mean

Discussion

A large-scale population study of central corneal thickness, corneal curvature, and GAT in different ethnic groups is difficult. As a substitute for such a study, we chose to review charts of patients who underwent presurgical examinations at a refractive surgery center. That is not an ideal unbiased population in terms of comparing racial variations, but our primary intention was to collect a sufficiently large database for statistical comparison of other parameters. It was our concern that

Acknowledgements

We acknowledge statistical consultation by Ms Melissa L. Earl, MPH, Director, Innovative Medical and Epidemiology Data Solutions, Moreno Valley, California.

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