Objective Macular Asymmetry Metrics for Glaucoma Detection Using a Temporal Raphe-Based OCT Linearization Algorithm

Background/Objectives: We aim to develop an image linearization process and a program capable of quantifying vertical and left-right asymmetries observed in macular scans. We then sought to verify its applicability in clinical settings. Methods: In this single-center cross-sectional study, we examined 37 consecutive patients with unilateral open-angle glaucoma and analyzed paired data (glaucomatous eye vs. fellow normal eye). Spectral-domain OCT images were automatically processed by a custom program to align the disc-fovea axis and temporal raphe, and the following parameters were evaluated: (1) mean inner retinal thickness difference (superior-inferior), (2) Vertical Asymmetry Score, and (3) Quadrantal Asymmetry Score. Results: We analyzed 37 healthy eyes and 37 POAG eyes. After linearization, the mean inner retinal thicknesses for the normal and POAG groups were 93.4 µm (interquartile range [IQR]: 90.1-98.5) and 80.3 µm (IQR: 77.3-85.0), respectively. The Vertical Asymmetry Score was 6.80 (IQR: 6.15-7.25) for healthy eyes and 9.69 (IQR: 9.16-11.58) for POAG eyes. The Quadrantal Asymmetry Score was 6.35 (IQR: 5.94-7.19) for healthy eyes and 8.47 (IQR: 8.11-9.63) for POAG eyes. Significant differences were found between groups for all parameters (p < 0.001). The Vertical Asymmetry Score (AUC = 0.967, p < 0.001) and Quadrantal Asymmetry Score (AUC = 0.946, p < 0.001) demonstrated significantly greater accuracy in detecting glaucoma compared to the mean inner retinal thickness (AUC = 0.743). Conclusions: The developed linearization program and asymmetry scores have shown promise as parameters for objectively quantifying macular asymmetry using spectral-domain OCT. External validation in independent cohorts, including bilateral disease, is warranted.