Central corneal thickness of Caucasians and African Americans in glaucomatous and nonglaucomatous populations.

OBJECTIVE: To determine whether there is a difference in central corneal thickness between African American and Caucasian patients. If present, a difference might alter the measurement of intraocular pressure and potentially the assessment and management of glaucoma in these populations. METHODS: Central corneal thickness was measured by means of ultrasound pachymetry in African American (n = 56) and Caucasian (n = 32) patients with suspected or confirmed glaucoma and control populations of African American (n = 26) and Caucasian (n = 51) subjects in whom there was no evidence of elevated intraocular pressure or glaucomatous optic nerve damage. Measurements of central corneal thickness were then compared between different subpopulations by means and population distribution analysis. RESULTS: A statistically significant difference was noted between the mean (+/-SD) central corneal thickness of all African American (including those with and without glaucoma) (right eye, 531.0 +/- 36.3 microm; left eye, 530.0 +/- 34.6 microm) and all Caucasian (including those with and without glaucoma) (right eye, 558.0 +/- 34.5 microm; left eye, 557.6 +/- 34.5 microm) patients. Similar results were found when subpopulations were tested. Distribution analysis of central corneal thickness measurements noted the largest cluster of African American patients around 520 to 540 microm, whereas the largest cluster of Caucasian patients was between 580 and 600 microm. CONCLUSIONS: African Americans were found to have thinner central cornea thickness measurements than Caucasians. This finding in African Americans may lead to lower applanation intraocular pressure readings compared with those of Caucasians, potentially resulting in an underestimation of the actual level of intraocular pressure.