To analyze and quantify the changes in ocular surface parameters under conditions with different exposures to blue light from visual display terminals (VDTs).

This was a prospective intervention study. Fifteen non-medical administrative staff members at Hankou Aier Eye Hospital were recruited from October to December 2018 and were sequentially tested under 4 test conditions with different exposures to blue light. Then all subjects were sequentially tested under conditions without blue light for 2 hours (non-2 h group), with a low dose of blue light for 2 hours (low-2 h group), with a high dose of blue light for 2 hours (high-2 h group) and with a high dose of blue light for 4 hours (high-4 h group). Each test was conducted over an interval of 2 days to eliminate the effects of the previous test. Symptoms of subjects were evaluated by the Standard patient evaluation of eye dryness (SPEED) questionnaire. The other examinations were as follows: Lipi view ocular surface interferometer, OCULUS Keratograph 5M and slit-lamp microscopy. All examinations were repeated before and after each test. A general linear regression analysis, paired t test and rank sum test were used for statistical analysis.

With the non-2 h group as the control, the SPEED scores of the low-2 h group, high-2 h group and high-4 h group increased 2.07 points, 2.13 points and 4.20 points, respectively (P=0.001, P=0.001, P<0.001). The tear film break-up time decreased by 1.83 s, 0.27 s and 1.99 s, respectively (P=0.028, P=0.746, P=0.017). Compared to the non-2 h control group, the cornea and conjunctiva fluorescence staining scores in the high-4 h group and high-2 h group increased by 0.47 points, 0.43 points and 0.33 points, 0.30 points, respectively (P=0.008, P=0.014; P=0.036, P=0.048). The SPEED scores in the high-4 h group increased by 2.07 points compared to the high-2 h group (P=0.002), and by 2.13 points in the high-4 h group compared to the low-2 h group (P=0.003). There was a 0.4 point increase in corneal staining score in the high-2 h group compared to the low-2 h group (P=0.029). There were no statistically significant differences among other parameters.

The illuminance of blue light from VDTs and the operating time of VDTs affects the occurrence and development of dry eye disease. Reducing the dose of blue light from VDT screens can decrease the damage to the epithelial cells of the cornea and conjunctiva. Even with a low dose of blue light exposure, the group that was exposed to the VDT for 2 hours show a decrease in tear film stability and an increase in symptoms.

visual display terminal; blue light; dry eye; tear film