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Dorota Helena Szczesna-Iskander, Clara Llorens Quintana, Kasandra Swiderska; The effect of blinking pattern on tear film break-up time. Invest. Ophthalmol. Vis. Sci. 2018;59(9):4911.
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To assess the tear film break-up time (BUT) after natural and forced blinks using standard fluorescein test (FBUT) and two videokeratoscopes providing the non-invasive tear film break-up time (NIBUT) assessment. Additionally, the purpose was to test the performance of two videokeratoscopes in objective and subjective NIBUT evaluation.
K5M (Oculus, Germany) giving objective non-invasive Keratograph break-up time (NIKBUT) and E300 (Medmont, Australia) giving objective non-invasive break-up time (NTBUT) were used. Thirty-two volunteers (24F/8M) aged between 23 and 33 (25±2) years were recruited. They were asked to blink either naturally or forcefully and suppress further blinking for maximum 25s. The NIBUT was additionally assessed subjectively by one observer marking the first noticeable distortion in Placido rings reflection: NIKBUT_sub and NTBUT_sub for K5M and E300, respectively. The average of two NIBUT and three FBUT measurements was taken into analysis. At least 3 minutes break was kept between non-invasive measurements. The statistical analyses included nonparametric Wilcoxon test, ANOVA (Friedman), and post-hoc analysis with Tukey-Kramer correction.
The forced blink significantly shortened BUT measured and assessed with all applied methods (p<0.05). Statistically significant differences were found between NIKBUT, NTBUT and FBUT after natural and forced blink (χ2=0.31, p=0.016; χ2=9.19, p=0.010, respectively). K5M was identified as giving significantly different results to FBUT test after natural blink and to both FBUT and E300 after forced blink. However, no statistically significant differences were found between NIKBUT_sub and NTBUT_sub after both natural (p=0.619) and forced (p=0.059) blinks. There were no significant differences between NTBUT and NTBUT_sub (p=0.172) and NIKBT and NIKBUT_sub (p=0.380) after natural blink and between NTBUT and NTBUT_sub after forced blink (p=0.089), however there were differences between NIKBUT and NIKBUT_sub (p=0.030) studied after forced blink.
Attention should be given in instructing the subjects before BUT evaluation irrespectively to the method of measurement because a non-natural blink may affect the tear film spreading and hence the tear film stability. A forced blink could also result in differences in automatic estimators of tear film stability employed in instruments.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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