Abstract
Abstract: :
Purpose: Differences in corneal thickness can be a source of error in the measurement of intraocular pressure (IOP) by applanation tonometry. La Rosa, et al recently reported thinner corneas in African-Americans compared with Caucasians. The Ocular Hypertension Treatment Study also identified similar findings in its subjects. The present study compares previously characterized corneal thickness data for African-Americans and Caucasians with that for Latino-Americans, the most rapidly growing segment of the U.S. population. Methods: Central corneal thickness (CCT) was measured by ultrasonic pachymetry in Latino-American patients with suspected or confirmed glaucoma (n=34) and in control Latino-American patients (n=54) with no evidence of elevated IOP, optic disk cupping, or visual field defect. These measurements were then compared with corneal thickness data previously obtained from glaucomatous (n=56) and nonglaucomatous (n=26) African-Americans and glaucomatous (n=32) and nonglaucomatous (n=51) Caucasians. Results: A statistically significant difference was noted between mean (+/- SD) CCT of all Latino-American patients (right eye, 547.3 +/- 34.7 microns; left eye, 548.8 +/- 35.6 microns) and all African-American patients (right eye, 531.0 +/- 36.3 microns; left eye, 530.0 +/- 34.6 microns). The difference between mean (+/- SD) CCT of all Latino-American patients and all Caucasian patients (right eye, 558.0 +/- 34.5 microns; left eye, 557.6 +/- 34.5 microns) was not statistically signifcant. Latino-American corneas were thicker than African-Americans' and thinner than Caucasians' across all glaucomatous and nonglaucomatous subpopulations. There was a positive association between CCT and IOP (r=0.17, p=0.007) in the total population of control eyes, with a 0.75 mmHg increase in IOP for every 50 micron increase in CCT. Conclusion: African-Americans, as previously reported, have thinner corneas than Caucasians. Latino-Americans were found to have thicker central corneal thickness measurements than African-Americans and thinner central corneal thickness measurements than Caucasians, although the latter relationship was not statistically significant. This finding further supports existing evidence of ethnic or racial differences in CCT, suggesting that "normal" ranges of IOP, as measured by applanation tonometry, may vary depending on the population being evaluated.
Keywords: 444 intraocular pressure • 369 cornea: clinical science