The Effects of Chewing Gum in Preventing Eyestrain

Abstract

Purpose. To investigate the effects of chewing gum and tablet candy to reduce eyestrain in healthy individuals. Materials and Methods. A double-blinded crossover trial was conducted. Forty-six healthy individuals (23 men, 23 women) between 20 and 59 years old, feeling eyestrain, were enrolled. Each 10-year age group included 12 individuals except the 30s group, which included 10 individuals. A visual task was performed on reading material displayed on a computer screen at a fixed distance for 60 min. Gum or tablet candy of two pieces were chewed for two 15-min periods starting 15 and 45 min after starting to read. Subjects chewed gum on Day 1 and tablet candy on Day 2, and vice versa. Primary outcome is as follows: subjective eye fatigue (eye tiredness, eye heaviness, blurred vision, double vision, and eye dryness) using a visual analog scale (VAS). Secondary outcomes are as follows: subjective accommodation from near and far points of accommodation measured with a D’ACOMO, spherical equivalent refraction, and eye dryness by analyzing ring break-up time (RBUT) measured with the RT-7000 Auto Ref-Topographer. Results. The VAS scores of subjective eye fatigue were not significantly changed between chewing gum and tablet candy ( $P=0.397-P=0.909$ ). Those scores of eye tiredness and eye heaviness were significantly longer before and after the visual task with tablet candy ( $P=0.013$ and $P=0.025$ , respectively) but not with chewing gum. The changes of subjective accommodation were significantly lower after the visual task between chewing gum and candy ( $P=0.043$ ). There were significant differences among each age group (20 s vs. 30 s, $P=0.594$ ; 20 s vs. 40 s, $P=0.002$ ; 20 s vs. 50 s, $P=0.002$ ). After reading, the changes of spherical equivalent refraction did not indicate a shift toward myopia ( $P=0.267$ ). In the RBUT, there were no significant differences between the samples ( $P=0.680$ ). Conclusions. Chewing gum helps improve the ability of the eye to focus, especially in young adults.