# 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.

## Key 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.