Normative Exophthalmometry Measurements Vary Among Ethiopian Adults and the Major Ethiopian Ethnic Groups.

Abstract

Periocular and orbital anthropometric values vary among races. No studies have established normative exophthalmometry values for Ethiopians or the many Ethiopian ethnic groups. This study established a set of normative anthropometric values for exophthalmometry, and further evaluated whether these measurements differed based on sex or ethnic group. A cross-sectional study was performed in the ophthalmology department at St. Paul's Hospital in Addis Ababa, Ethiopia. Two hundred ninety-six participants were recruited for the study. Sex, primary Ethiopian ethnic subgroup, and exophthalmometry measurements were recorded. Differences between ethnicities and sexes were evaluated using independent samples t test. Average proptosis for the total cohort was 15.88 ± 2.49 mm, with 582 eyes measured. Females (15.87 ± 2.53, n = 286) and males (15.89 ± 2.49, n = 296) were not significantly different in their proptosis measurements. Within the 3 largest ethnic groups measured, Amhara (16.12 ± 2.67, n = 204), Oromo (15.43 ± 2.51, n = 172), and Gurage (16.23 ± 2.59, n = 98), the difference in proptosis measurement was significant between the Amhara and Oromo groups (p = 0.01), and the Oromo and Gurage groups (p = 0.01). The only ethnic group that was significantly different between sexes was Gurage, of which average female proptosis was 15.51 ± 2.74 (n = 54), while male proptosis was 17.13 ± 2.11 (n = 44) (p < 0.01). Mean Ethiopian proptosis values vary across ethnicities, are similar to those measured in other African populations, but are lower than those established in African-American populations. This study provides an important resource that Ethiopian ophthalmologists can use when evaluating patients with suspected ophthalmic and orbital disease.