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Carolina T. Pinto, Denny M. Garcia, Antonio Augusto V. Cruz; Spontaneous Blink Rate And Interblink Time Distributions. Invest. Ophthalmol. Vis. Sci. 2011;52(14):4703.
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© ARVO (1962-2015); The Authors (2016-present)
It is agreed that subjects with identical spontaneous blink rate (SBR) may display different distributions of the time interval between consecutive blinks (interblink time interval or IBI). The purpose of the present work is to report an analysis of SBR over a long period of observation.
Twenty subjects divided into two groups of 10 (controls and patients with Graves orbitopathy) had their SBR measured when watching a commercial movie during one hour. The control group was formed by 5 men and 5 women aged 27 to 61 (46.0 ± 13.6; mean ± SD). The Graves group comprised of 3 men and 7 women, aged 33 to 61 (46.7± 8.9; mean ± SD) with Graves upper eyelid retraction. Magnetic search coil was employed to continuously register the spontaneous blinking movements during the experiment.
Neither the overall mean SBR (controls = 19.8 ± 4.9 SD, Graves = 17.6 ± 5.4 SD) or IBI time (controls = 5.2 ± 3.1 SD, Graves = 7.9 ± 3.5 SD) differed between the two groups. When the number of blinks was plotted in bins of 5 minutes, both parameters were quite variable along the time of observation. The coefficient of variation of the means for controls and Graves were SBR = 29.6 % and 36.7 %; IBI = 44.9% and 44.6%. When the whole time of observation was considered, the IBI distributions of all subjects were highly positively skewed with skewness coefficient greater than 1.0. However, when the individual distributions were analyzed in bins of 5 minutes of duration a wide dispersion of the skewness of coefficient was verified with some subjects showing coefficients ranging from -1.0 to 1.0.
Despite the highly variability of the SBR over time all IBI distributions were positively skewed including those of the patients with Graves orbitopathy. This means that the spontaneous blinking process is characterized by a high number of blinks with short time interval followed by a decreasing number of longer interblink periods. Our results indicate that the finding of different classes of IBI distributions is a sampling artifact resulting from the small size of the samples analyzed.
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