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

Background/Aims: 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 diagnosed with open-angle glaucoma in one eye, with the other eye being normal. Spectral-domain OCT images were automatically processed by a program we developed to straighten the disc-macula and macula-temporal raphe lines. The following parameters were then analyzed: 1) Mean inner retinal thickness difference between the superior and inferior segments, 2) Vertical Asymmetry Score, and 3) Quadrantal Asymmetry Score. These parameters were automatically measured, and their values were compared between the two eyes.. Results: We analyzed 37 healthy eyes and 37 POAG eyes. After linearization, the mean inner retinal thickness for the normal and POAG groups was 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). Conclusion: The developed linearization program and asymmetry scores have shown promise as parameters for detecting glaucomatous changes in macular scans using spectral-domain OCT.