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M. Chen, C. Begley, H. Liu, N. Himebaugh; Analysis of Blink Parameters and Tear Film Instability With Tasks. Invest. Ophthalmol. Vis. Sci. 2010;51(13):3367.
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While it is recognized that the purpose of the blink is to lubricate the corneal surface, few have studied the relationship between blinking and the tear film. This study investigated how the parameters of the blink changed with concentration (internal controls) and surface anesthetic (external controls) and whether the blink adequately rewetted the corneal surface.
Ten subjects (2 males and 8 females) completed the Dry Eye Questionnaire (DEQ). A small reflective dot was placed on one eye and 2µl of 2% sodium fluorescein was instilled. Tear film stability and blinking (via tracking of dot) were monitored by 2 digital cameras while listening to music and playing a computer game, with and without anesthetic. Blink rate (BR) and amplitude (BA), and up (UPV) and down phase velocity (DPV) and the area of tear break-up (TBU) were analyzed using custom designed MATLAB programs.
BR (AVG/min ±Std) was significantly slowed (paired t-test, p<0.02) during the game (8.87±6.06 without and 5.63±5.75 with anesthetic) compared to music (15.12±10.43 without and 14.3±10.57 with anesthetic). Other blink parameters (%BA, UPV%/sec, DPV%/sec) were the following: game with (59.08/2.31/7.08) and without anesthetic (66.84/2.44/7.93); music with (66.03/1.95/6.26) and without (67.98/1.9/6.83) anesthetic. Both UPV and DPV were significantly increased with the game compared to music and the DPV was significantly decreased with anesthetic (t-test, p<0.01). The AVG TBU% (before/after each blink) was significantly greater during the game, both with (25.31/14.15) and without (15.17/10.66) anesthetic, compared to music with (17.96/12.29) and without (10.52/8.77) anesthetic.
. During the game, the BR slows and UPV and DPV increase, suggesting that central/internal controls over blinking act to minimize interruption of concentration by the eyelids. Anesthetic slowed the DPV, which suggests an ocular surface/external input to blinking. Our results also indicate that many blinks are not full, especially when concentrating on a task, and often do not fully re-lubricate the corneal surface.
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