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

TL;DR

This study introduces a new automated method to detect glaucoma by measuring macular asymmetry using OCT scans, showing strong diagnostic potential.

Contribution

A novel linearization program was developed to objectively quantify macular asymmetry for glaucoma detection.

Findings

The Vertical and Quadrantal Asymmetry Scores showed significantly higher accuracy in detecting glaucoma compared to mean retinal thickness.

All parameters showed significant differences between healthy and glaucomatous eyes (p < 0.001).

The method demonstrated high diagnostic performance with AUC values of 0.967 and 0.946 for the Vertical and Quadrantal Asymmetry Scores, respectively.

Abstract

What is already known:

Macular inner retinal layer asymmetry is associated with glaucoma, but objective and standardized quantification has been limited.

What this study adds:

A fully automated linearization program was developed to align the disc–fovea and temporal raphe axes, enabling reliable macular asymmetry scoring with high diagnostic performance.

How this might affect practice:

Objective asymmetry metrics may help identify unilateral or asymmetric glaucomatous changes and support standardized macular OCT interpretation; external validation in broader and bilateral-disease cohorts is required.

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.

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