# Unraveling Visual Field Asymmetry: Insights Into Left-Right Differences in Glaucoma Patients

## TL;DR

This study examines left-right visual field differences in glaucoma patients and finds that asymmetry is not useful for distinguishing between glaucoma types, but is linked to eye structure in primary open-angle glaucoma.

## Contribution

The study identifies anterior chamber depth as a novel factor influencing visual field asymmetry in primary open-angle glaucoma.

## Key findings

- No significant visual field asymmetry differences were found between primary and secondary glaucoma types.
- In primary open-angle glaucoma, shorter anterior chamber depth correlates with greater left-right visual field differences.
- 24.6% of primary open-angle glaucoma patients showed a 10 dB or greater left-right difference in visual field tests.

## Abstract

Purpose: Primary open-angle glaucoma (POAG) typically exhibits bilateral symmetry in visual field defects, while secondary glaucoma often manifests substantial left-right differences. This study investigates the diagnostic relevance of left-right differences in the Humphrey visual field (HVF) test and explores the factors influencing these differences.

Study design: This is a cross-sectional study.

Methods: Parameters were assessed in 201 glaucoma patients, including age, sex, glaucoma disease type, central corneal thickness (CCT), corneal endothelial cell density (ECD), axial length, anterior chamber depth, refractive power, intraocular pressure (IOP), glaucoma drug score, and mean deviation (MD), pattern standard deviation (PSD), and visual field index (VFI) for both eyes in HVF. Patients were categorized into type 1 (POAG in both eyes) and type 2 (secondary glaucoma). Multivariable analysis was conducted to explore factors influencing left-right visual field test differences.

Results: No significant differences were found between type 1 and type 2 in left-right MD, PSD, and VFI (p=0.13, 0.26, 0.09). Type 2 exhibited significant inter-eye differences in ECD, CCT, IOP, and glaucoma drug scores (p=0.02, <0.01, <0.001, 0.01). In the type 1 group, the left and right MD values were statistically significantly correlated (r=0.40, p<0.000001), but 24.6% of patients showed a left-right difference of 10 dB or more. Multivariable regression analysis identified anterior chamber depth as the sole significant factor influencing left-right MD differences in POAG (p=0.03).

Conclusion: Asymmetry in the visual field cannot distinguish between glaucoma disease types. In POAG, a shorter anterior chamber depth is associated with increased left-right MD differences, emphasizing its significance in understanding the progression of visual field defects.