Assessment of silent reading ability among glaucoma patients using an eye tracking system with horizontally scrolling text.

Purpose: There have been many reports suggesting that glaucoma patients with visual field defects may have decreased silent reading ability compared with individuals without glaucoma. This study used an eye tracking system to assess the ability of glaucoma patients to silently read horizontally scrolling text.

Methods: Glaucoma patients who met the following criteria were recruited: age of ≤ 70 years, at least one eye with a 10 - 2 threshold on standard automated perimetry, a mean deviation value of n 4.0 dB or less, and corrected decimal visual acuity of 0.7 or better in both eyes. Using heat map images created from data from an eye tracking system operating during presentation of a video in which a sentence scrolled horizontally from right to left, reading time, average gaze position, and average fixation time (AFT) were compared between normal eyes (23 individuals, 46 eyes) and glaucomatous eyes (25 patients, 45 eyes). Four styles of sentences (large slow, large fast, small slow, and small fast) were scrolled in the top or bottom sections of the screen.

Results: Primary open-angle glaucoma was the most common type of glaucoma in 34 eyes (75.6%), followed by secondary glaucoma in six eyes (13.3%). In comparison with normal eyes, the reading time among right eyes was significantly longer in glaucomatous eyes when reading large fast text that was shown in the bottom area and left glaucomatous eyes showed a leftward shift in gaze position in the top, bottom, or both sections with all four sentence types. There was no significant difference in AFT between glaucomatous and normal eyes across the four sentence styles. In the left eye with inferior visual field loss, text presented at the top consistently showed a correlation with leftward shift of the gaze position across all scenarios.

Conclusion: Glaucoma patients with central visual field defects in their left eyes may experience greater difficulty reading horizontally scrolling text than individuals with normal eyes.