Blink rate, blink amplitude, and tear film integrity during dynamic visual display terminal tasks

The present study aimed at investigating the influence of the level of dynamism of two different visual display terminal tasks on spontaneous eyeblink rate, blink amplitude, and tear film integrity.

A total of 25 healthy, young volunteers participated in the study. Blink rate and blink amplitude were recorded in silent primary gaze conditions and while subjects were playing two computer games of similar cognitive demands but different rate of visual information presentation. For each experimental condition, tear volume was evaluated by measuring meniscus height and with the red phenol thread test. Fluorescein and non-invasive break-up time tests, as well as the observation of interference patterns and the estimation of the dry area extension, were employed to assess tear stability.

Statistically significant differences were revealed in blink rate (F = 595.85, p < 0.001) and blink amplitude (χ(2) = 34.00, p < 0.001), with blink rate during fast- and slow-paced game play decreasing to almost 1/3 and 1/2 of baseline levels, respectively, and with a larger percentage of incomplete blinks during dynamic tasks. Fluorescein and non-invasive break-up time tests and dry area extension were able to differentiate between experimental conditions in general (F = 408.42, p < 0.001; F = 163.49, p < 0.001; χ(2) = 20.74, p < 0.001), as well as between fast- and slow-paced games, thus suggesting that tear quality was more affected than tear volume.

Blink rate, blink amplitude, and tear film stability were compromised during the most dynamic visual display terminal task, suggesting a negative influence of not only the cognitive aspects of the task, but also of the rate at which new visual information is presented. Frequent breaks and blinking awareness training are recommended for visual display terminal users requiring prolonged periods of visually demanding dynamic computer play or work.