Determination of the normal range of exophthalmometric values for Ethiopian adults at Menelik II Hospital, Addis Ababa, Ethiopia

Abstract

Background: Many orbital diseases can cause proptosis, including thyroid-associated orbitopathy, tumors, inflammation, head and orbital trauma, and craniofacial abnormalities. In patients for whom orbital diseases are suspected, exophthalmometry is an established method of routine evaluation. The objective of this study was to establish a set of exophthalmometric values in a normal Ethiopian adult population.

Subjects and Methods: A cross-sectional study of clinically normal Ethiopians in the age range of 18 years and above, attending the outpatient department of ophthalmology in Menelik II Hospital, Addis Ababa, from May to September 2018, were included in the study. Hertel’s mirror exophthalmometer was used to determine inter-orbital distance and exophthalmometric values of both eyes. Data were collected using a structured format, entered in an Excel spreadsheet, and analyzed using Stata version 14 statistical package.

Results: A total of 2,133 subjects were included in the study, of whom 1,220 (57.20%) were males and 913 (42.80%) were females. The ages ranged from 18 to 98 years (mean=40.79±16.84 years). The mean inter-orbital distance was 113.16±3.99mm. The mean exophthalmometric value for the right eye and left eye in both sexes was 115.77±2.65mm and 115.71±2.62mm, respectively. The mean inter-orbital distance was 114.33mm for males and 111.61mm for females. This value difference was statistically significant with p=0.00. The mean inter-orbital distance and mean exophthalmometric values in different age ranges, ethnic groups and sex were statistically significant, (p=0.00) and (p=0.04) respectively. The mean exophthalmometric values for left eye was 15.80mm for males and 15.58mm for females. This difference was statistically insignificant (p=0.05).

Conclusions: The normal inter-orbital distance of Ethiopian adults was found to be 113mm, and exophthalmometric values for right eye and left eye were 15.77mm and 15.71mm, respectively. The exophthalmometric values were consistent between right and left eyes, with a maximum relative difference of 2mm. Sex and ethnicity had a significant effect on inter-orbital distance while, sex, age range and ethnicity had a significant effect on protrusion of right and left eyes. Ethiop. J. Health Dev. 2019; 33(4):269-275]

Key words: Inter-orbital distance, exophthalmometry, ethnicity, Ethiopian adults