Objective: To explore the impact of glaucoma on the retinal nerve fiber layer (RNFL) optical density ratio (ODR) by volumetric optical coherence tomography (OCT) under different analytical radii.
Methods: Twenty-five eyes identified as healthy and 57 eyes with a glaucoma diagnosis (23 mild and 34 moderate-advanced cases) underwent volumetric OCT scans centered at the optic nerve head. Cross-sectional images were obtained through 5 distinct analytical circles with varying radii. The distribution of RNFL ODRs was analysis and compared between normal eyes and glaucomatous eyes.
Results: RNFL ODRs displayed significant variation in relation to their location across all examined eyes and respected the ISTN rule (inferior > superior > nasal > temporal, all p < 0.05). The ODRs differed significantly between normal and glaucomatous groups (all p < 0.001), decreasing as glaucoma progresses, both on average and in each quadrant of all analytical circles (all p < 0.001). The RNFL ODRs correlated significantly with the MD (R2 ranging from 0.553 to 0.585, all p < 0.001), with the most pronounced difference noted in the inferior-temporal sector between groups.
Conclusions: RNFL ODRs by OCT imaging could serve as a valuable tool for detecting retinal nerve fiber defects in glaucomatous eyes.
Keywords: Optical coherence tomography; glaucoma; image analysis; optical density ratio; retinal nerve fiber layer.