Exophthalmometry values of Turkish adult population and the effect of age, sex, refractive status, and Hertel base values on Hertel readings.

PURPOSE To establish normal exophthalmometry values in the adult Turkish population, and the impact of age, gender, interpupillary distance, Hertel base selection, and refractive status on globe position. METHODS Exophthalmometry measurements and refractive status of 2477 subjects were conducted in one tertiary and five primary health care centers. Change of globe position by age, intersex differences in terms of globe position, correlations of Hertel base with exophthalmometry results, and interpupillary distance (IPD) were evaluated. Multiple linear regression analysis was performed to test determination effect of each variable on final Hertel reading. RESULTS Median Hertel reading was 13 mm, and 95% of the population had an upper limit of 17 mm for both eyes. There was a negative correlation between spherical equivalent of refractive status and exophthalmometry results and a weak positive correlation between IPD and exophthalmometry result. Mean Hertel value was found to decrease significantly after the third decade. Hertel base value was found to have moderate linear correlation with Hertel results. A weak correlation was detected with Hertel base/IPD ratio with final Hertel results. Multiple linear regression analysis was performed and only 13% and 20% of change in Hertel values bilaterally were found to be determined by other variables (age, IPD, refractive status, and Hertel base value) for females and males. CONCLUSIONS Normative dataset for exophthalmometry results of the Turkish population is established to be used in clinical practice and research. Only 13% to 20% of change in Hertel values was detected to be determined by age, IPD and Hertel base values.