Characterization of Gaze Metrics and Visual Search Pattern Among Glaucoma Patients While Viewing real-world Images.

Abstract

Prcis: We quantified and compared the gaze metrics during target-oriented visual search tasks between glaucoma and healthy controls. Based on a mathematical concept we showed that due to glaucoma, focal search becomes prominent over global search.

Purpose: Visual Search (VS) which is essential for target identification and navigation is significantly impacted by glaucoma. VS metrics can be influenced by differences in cultural exposure or coping strategies, leading to varying VS patterns. The aim of this study was to explore and label the pattern of VS based on gaze metrics quantified using eye-tracking technology.

Methods: Twenty-seven glaucoma subjects and thirty healthy controls (median age 51 (14) and 54 (19) years respectively) underwent a VS experiment during which they had to identify specific targets from real-world images. Eye movements were recorded using a remote eye-tracker and gaze metrics - Fixation Count (FC), Fixation Duration (FD), Saccade Amplitude (SA), and VS Time (VST) were computed and compared between the study groups. A Z-score-based coefficient 'K' was derived to label the search patterns as global (K ≤ - 0.1: short FD with long SA), focal (K ≥ +0.1: long FD with short SA), or a combination (K between +/-0.1).

Results: Similar to other ethnicities, Indian glaucoma subjects also exhibited statistically significantly increased FC, FD, and VST (P=0.01). Healthy controls presented a comparable proportion of focal (47%) and global (42%) search patterns while glaucoma subjects exhibited predominantly focal (56%) than global search patterns (26%, P=0.008).

Conclusions: This study suggests that glaucoma subjects perform more focal search during active gaze scanning. This change in viewing behavior reflects underlying compensatory strategies adapted for coping with their visual impairments. These search patterns can be influenced by factors such as saliency which requires further investigation.