A pilot study of the impact of repeated blink refrainment on ocular surface temperature and the interblink period.

Abstract

This study examines a potential stress test of repeated blink refrainment and its effects on the interblink period and the rate of evaporative ocular surface cooling. Such a test could aid in the study of computer vision syndrome, in which screen users unconsciously delay blinking, leading to onset of symptoms. This study aimed to examine the relationship between the length of the maximum achievable interblink time and the rate of ocular surface cooling under stress test conditions of repeated refrainment from blinking for as long as possible. Subjects acclimated to the examination room for 10 minutes before measurement and then were asked to hold the eyes open and refrain from blinking for as long as possible (the maximum blink interval), while ocular surface temperature was recorded using an infrared thermographic video camera. Subjects completed 20 trials with four successive blinks separating each trial. Fifteen subjects (8 female and 7 male subjects) completed the study. The grand mean ocular surface cooling rate was -0.027°C/s (range, -0.338 to +0.014°C/s). A faster ocular surface cooling rate was significantly related to an exponentially shorter maximum blink interval (p<0.001). An increasing number of trials was related to a clinically insignificant increase in the length of the maximum blink interval overall, and a post hoc analysis revealed subject subgroups for whom the stress test was effective or ineffective. The ocular surface evaporatively cools exponentially during periods of blink refrainment. With a subgroup of subjects with initially stable tear films and normal lipid layer thickness, cumulative tear film stress from repeated, longer-term blink refrainment could contribute to tear evaporation and symptoms of computer vision syndrome.