# Extraction of three-dimensional shapes in glaucoma patients in response to monocular depth cues

## TL;DR

This study shows that glaucoma patients have trouble perceiving 3D shapes using monocular depth cues, even when their visual field appears normal.

## Contribution

The study reveals that perceptual deficits in glaucoma patients extend beyond visual field loss to include 3D shape perception.

## Key findings

- Glaucoma patients had reduced accuracy in distinguishing 1D luminance brightness and larger depth errors for 3D-SfM and 3D-SfS.
- Patients with 100% VFI still showed larger depth errors for 3D-SfM compared to healthy volunteers.
- No correlation was found between error-in-depth values and VFI values in glaucoma patients.

## Abstract

To assess the impact of glaucoma on perceiving three-dimensional (3D) shapes based on monocular depth cues.

Clinical observational study.

Twenty glaucoma patients, subjected to binocular visual-field sensitivity (binocular-VFS) tests using a Humphrey Visual Field Analyzer, and 20 age-matched healthy volunteers, underwent two tasks: identifying the nearest vertex of a 3D shape using monocular shading (3D-SfS), texture (3D-SfT), or motion (3D-SfM) cues, and distinguishing elementary one-dimensional (1D) features of these cues. The association of the visual-field index (VFI) of binocular-VFS with 3D shape perception in glaucoma patients was also examined.

Glaucoma patients demonstrated reduced accuracy in distinguishing 1D luminance brightness and a larger "error-in-depth" between the perceived and actual depths for 3D-SfM and 3D-SfS compared to healthy volunteers. Six glaucoma patients with a 100% VFI for binocular-VFS exhibited a similar error-in-depth to the other fourteen glaucoma patients; they had a larger error-in-depth for 3D-SfM compared to healthy volunteers. No correlation between the error-in-depth values and the VFI values of binocular-VFS was observed.

The 3D shape perception in glaucoma patients varies based on the depth cue's characteristics. Impaired 1D discrimination and larger thresholds for 3D-SfM in glaucoma patients with a 100% VFI for binocular-VFS indicate more pronounced perceptual deficits of lower-level elementary features for 3D-SfS and higher-level visual processing of 3D shapes for 3D-SfM. The effects of the location and degree of binocular visual-field defects on 3D shape perception remain to be elucidated. Our research provides insights into the 3D shape extraction mechanism in glaucoma.