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M. E. Jansen, C. G. Begley, N. L. Himebaugh, M. Chen; Blinking and Tear Break-Up in Soft Contact Lens Wearers. Invest. Ophthalmol. Vis. Sci. 2008;49(13):4836.
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It is well known that the frequency of blinking decreases with tasks requiring concentration, and that contact lens (CL) wear is associated with more frequent blinking. However, blinking patterns of CL wearers engaged in different tasks have not been measured. The purpose of this study was to determine whether CL wear affects tear stability, the fullness of the blink, and the interval between blinks when subjects were involved in different tasks.
Ten subjects (6 female, 4 male), who had not worn their soft contact lenses for 24 hours were seated behind a slit lamp biomicroscope custom equipped to simultaneously measure blinking via a high speed video camera (120 Hz) and tear break-up with retroillumination (RI) of the pupil using infrared light. Three measurements of 55 sec each were taken while subjects listened to music and then played a video game. These procedures were then repeated with the subjects’ habitual contact lenses. Each subject completed the Current Symptoms Questionnaire (CSQ) before and after each set of tasks to determine symptoms of ocular irritation.
Without CL, the interblink interval (IBI) significantly increased (AVG music=3.0±1.0sec; AVG game=7.5±2.1sec), and the blink amplitude (BA) decreased (AVG music=77.1%±14.2%; AVG game=53.1%±21.5%) when subjects played a video game versus listened to music (paired t-test, p≤0.001). With CL, the BA significantly decreased (AVG music=84.0%±11.0%; AVG game=65.3%±9.6%, p<0.001), but the IBI showed only a minimal increase (AVG music=1.8±0.5sec; AVG game=2.5±0.9sec). The RI images often showed horizontal lines of tear disruption marking the extent of the blink both with and without CL. Ocular symptoms increased after playing the game with CL.
During tasks requiring concentration, the blink rate decreased (IBI increased) and there were many incomplete blinks (BA decreased) without CL. With CL, tear film instability increased. Blinking frequency also increased, but it remained high when subjects played the video game, and symptoms of ocular irritation increased. Increased blinking with CL may be due to vision disruption secondary to tear instability and drying of the lens, resulting in symptoms of ocular discomfort.
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