To evaluate the change in blink rate in adolescents according to the type and duration of computer tasks and to analyze the risk of ocular dryness using an ocular protection index.

Fifteen male high school students played computer games and viewed Internet lectures for 20 minutes each. Blink rate was measured by USB camera, and ocular protection index (OPI, the ratio of BUT to inter-blink interval) was calculated for each subject during the two tasks. In addition, 7 of the 15 subjects played computer games again for 40 minutes on another day, and the change in blink rate according to the duration of computer games was observed.

The average blink rate was 5.44±3.29 per minute (median 5, range 2-12.75) while playing computer games and 20.63±11.21 per minute (median 18.25, range 4.93-42.2) while viewing Internet lectures, and this difference was statistically significant (p=0.001). The percentage of subjects with OPI values less than 1 was 53& for computer games and 13& for Internet lectures (p=0.025). While playing computer games for 40 minutes, the mean of total blinks during ten-minute intervals decreased over time: 59.43 times (median 57) during the first 10 minutes, 33.86 times (median 41) during the last 10 minutes.

The blink rate in adolescents was significantly lower and the risk of ocular dryness was higher while playing computer games compared with that of viewing internet lectures. As playing time increased, the blink rate decreased and risk of ocular dryness increased.