Sustained Gazing Causes Measurable Decline in Visual Function of Patients with Dry Eye

Purpose: To assess the effects of sustained gazing on visual function of dry eye patients. Design: Prospective, comparative before-and-after study. Methods: A total of 176 patients with dry eye and 33 control subjects ≥50 years old were included. Dry eye symptomatology along and clinical parameters were assessed. Out-loud reading speed was measured using the International Reading Speed Test (IReST) as words per minute (wpm). Reading speed was repeated using different IReST excerpts following 30-minute silent reading. Results: At baseline, there were no differences between dry eye patients and control subjects with respect to reading speed (172 vs 180 wpm, respectively; P = 0.21) or the time to read the excerpt (33 vs 30 seconds, respectively; P = 0.17). After silent reading, the dry eye patients had decreased reading speed and increases in the length of time to read the passage compared to baseline (161 vs 172 wpm, respectively; P = 0.002; and 38 vs 33 seconds, respectively; P < 0.001). The control subjects did not show significant differences for either parameter. There were significant differences with respect to both parameters between the dry eye and control groups after sustained gazing (161 vs 188 wpm, respectively; P = 0.006; and 38 vs 31 seconds, respectively; P = 0.003). Each 1-point increase in baseline corneal staining score (0-6) led to a 5-wpm reduction in reading speed (95% confidence interval, −8 to −1; P = 0.01). Conclusions: Sustained gazing, such as in silent reading, has a measurable negative impact on visual performance of dry eye patients. Corneal staining represents a clinical parameter relevant to visual function.