Effect of Different Intensities of Blue Light Shielding on Visual Function of Normal Adults

Abstract

Objective: To investigate the influence of different intensities of blue light shielding on the visual function of healthy adults. Methods: This self-controlled study enrolled 20 healthy adults who were students volunteers of Tongji University from August 2016 to March 2017. The subjects completed a 75-min reading task illuminated by blue light (440 nm) at shielding intensities of 0%, 20%, 30%, 40%, and 60%. Twenty-four color partial scoreswere calculated to detect variations in color discrimination. After completing the reading task, visual fatigue, accommodation response, and lens accommodation were assessed and compared amongthe five intensities of blue light shielding. The results were analyzed by signed-ranked test. Results: The scores of many colorswere significantly lower at blue light intensities of 30%, 40%, and 60% compared to 0% intensity shielding (P < 0.05). The differences in color scores between 0% and 20% intensity shielding were not statisticallysignificant. After completing the reading task, the visual fatigue scores were lower with 20%, 30%, 40%, and 60% intensity shielding compared to 0% intensity shielding (all P < 0.05). The difference between before and after reading task in accommodation amplitude and positive relative accommodation were significantly lower at 20%, 30%, 40%, and 60% intensity shielding compared to 0% shielding (P < 0.05). Difference between before and after reading task in native relative accommodation were significantly lower at 40% and 60% intensity shielding compared to 0% shielding (P < 0.05). The differences betweenthe before and after reading task values of the 20% and 30% shielding were not significantly different from the 0% shielding. Lastly,differences between before and after reading task in lens accommodation at 20%, 30%, 40%, and 60% intensity shielding were not significantly different from 0% shielding. Conclusions: With blue light (centered at 440 nm) shielding of 20% to 60% intensity 20 band wavelength, the accommodation and visual fatigue of healthy adults improved.When the shielding intensity was 30% to 60%, the color perception was worse. Key words: blue light; video terminal syndrome; accommodation responses; visual fatigue; color discrimination