Abstract
Abstract: :
Purpose: It is well known that African Americans are much more likely to develop glaucoma than Caucasians and much more likely to progress to blindness. Recent studies show that central corneal thickness is a factor that predicts the development of primary open angle glaucoma (POAG). In these studies, the authors did not differentiate people of African decent into African Americans and Caribbean Islanders. This study was undertaken to compare the central corneal thickness measurements of Caucasians, African Americans, and Caribbean Islanders. Methods: One hundred and forty–five subjects were prospectively examined. Ethnicity and age were self–reported. Subjects with glaucoma or prior ocular surgery were excluded from the study. The average of three readings using ultrasound pachymetry were taken by single examiner on each eye and recorded as a measure of central corneal thickness. Mixed linear models were used to determine whether any association between central corneal thickness and gender, age, and ethnicity existed. Results: One hundred and forty–five participants (290 eyes) were included in the study with the following characteristics: 1. Ethnicity: Caucasian 39.3%, African American 39.3%, Caribbean Islander 21.4% 2. Sex: Caucasian 77.2% female, African American 59.6% female, Caribbean Islander 67.7% female 3. Mean Age: Caucasian 64.4 years, African American 51.2 years, Caribbean Islander 56.2 years We found no univariate effect of gender or age on central corneal thickness, making this a statistically valid comparison between ethnicities. Ethnicity was a significant predictor of central corneal thickness. Mean corneal thickness was 586 um (micrometers) +/– 5 um for Caucasians, which was significantly greater (p<0.0001) than for Caribbean Islanders (507 um +/– 8 um) and for African Americans (525 um +/– 5 um). Mean thickness did not statistically differ among the latter two groups (p=0.131) Conclusions: This study suggests that African Americans and Caribbean Islanders have thinner corneas than Caucasians. No significant differences in corneal thickness were found between African Americans and Caribbean Islanders. The Ocular Hypertension Treatment Study found that African American race was not an independent variable in predicting the development of POAG. It is possible that African decent is a marker for a thin cornea. There may be structural characteristics associated with a thin central cornea that predispose to POAG. We are uncertain as to why a thin central cornea predisposes to the development of glaucomatous changes.
Keywords: intraocular pressure • clinical (human) or epidemiologic studies: risk factor assessment • cornea: clinical science