Retinal Changes in Different Grades of Retinal Artery Occlusion: An Optical Coherence Tomography Study

Purpose: To investigate layer-by-layer changes in retinal thickness and reflectivity regarding the severity grade of acute retinal artery occlusion (RAO) using spectral-domain optical coherence tomography (SD-OCT). Methods: This study is a retrospective, observational case-control series that took place in an institutional setting and included 148 eyes from 74 patients diagnosed with acute RAO (central or branch). SD-OCT examinations were taken at baseline. Based on OCT findings, RAO was categorized into three grades (incomplete, subtotal, total). The thickness and reflectivity of selected retinal layers were measured from SD-OCT images. The data were compared across the three grades and against the contralateral eyes (controls). The main outcome measures were thickness and reflectivity of selected retinal layers. Results: The thickness of the inner and middle retinal layers differed significantly across the three RAO groups (P < 0.001), whereas the outer retinal layer thickness remained not significantly different. Reflectivity values showed statistically significant differences in the inner, middle, and outer retinal layers, but not in the vitreous body (P < 0.001). Conclusions: The reflectivity changes of selected retinal layers differ significantly regarding different grades of RAO. SD-OCT reflectivity measurement may be used as a noninvasive method to estimate the grade of retinal ischemia in RAO.