Abstract
Purpose :
To evaluate variation of the ovality index of optic disc caused by horizontal duction.
Methods :
Fundus photography was performed in 17 right eyes of 17 normal volunteers in central gaze and 5, 10, and 15 degrees of adduction and 5 degree of abduction. The ovality index was assessed by the maximal-to-minimal optic disc diameter ratio. We compared the ovality index between central gaze and each horizontal duction.
Results :
The mean maximal optic disc diameter didn’t change during horizontal duction, while minimal optic disc diameter decreased during adduction and increased during abduction. The mean ovality index was 1.19 ± 0.13 in central gaze. The ovality index decreased during adduction (1.14 ± 0.14 in 5-degree, 1.12 ± 0.14 in 10-degree, and 1.13 ± 0.14 in 15-degress adduction) and increased during abduction (1.23 ± 0.16). Compared to ovality index in central gaze, there were significant changes of ovality index by horizontal duction. (p = 0.0001, 0.002, 0.002, 0.007, respectively)
Conclusions :
The ovality index of the optic disc measured using fundus photograph is affected by horizontal duction.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.