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

Abstract

Purpose: 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.

Methods: 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.

Results: 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).

Conclusions: 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.