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Ziwei Wu, Carolyn G Begley, Ping Situ, Trefford L Simpson; Blinking and the Sensory Response to Increasing Air Stimulation at the Ocular Surface. Invest. Ophthalmol. Vis. Sci. 2014;55(13):3647.
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© ARVO (1962-2015); The Authors (2016-present)
Understanding the ocular surface inputs for blinking and sensation is important for dry eye and related conditions, particularly since the ocular surface input for blinking is controversial. The purpose of this study was to determine how increasing ocular surface stimulation affected blinking and sensation, while controlling task concentration.
Ten healthy subjects played video games to control their concentration, while seated behind a slit lamp biomicroscope fitted with a custom device generating air flow (AF) toward the central cornea. After estimating the AF threshold resulting in increased blinking, 6 levels of stimuli were randomly presented 3 times each and subjects used visual analog scales to record their sensory responses. The interblink interval (IBI) and the AF were recorded simultaneously and MATLAB programs determined IBI, sensory response and corresponding AF for each trial. A blink increase threshold (BIT), the AF associated with a statistically significant decrease in IBI, was calculated for each subject.
Blinking was highly variable between subjects at baseline, with a mean IBI (±SD) of 5.69±3.92sec. The BIT (±SD) was 98±26 ml/min air flow with IBI=2.84±1.19sec (permutation test, p<0.001). After log transformation, there was a significant linear function between increasing AF and decreasing IBI within each subject (-0.859≥ Pearson’s r≥ -0.987, p<0.05). The IBI was correlated with watery, discomfort and cooling ratings (Pearson’s r= -0.737, -0.606 and -0.632, p<0.001).
In normals, ocular surface stimulation increases blinking, following a dose response relationship. Blinking was correlated with ocular surface sensation, presumably due to their common ocular surface input. The BIT, a novel metric introduced here, may provide additional endpoints for dry eye or other ocular surface studies.
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