Department of Optics and Photonics, Wroclaw University of Science and Technology, Wroclaw, Poland.
Department of Optometry and Vision, Faculty of Optics and Optometry, Complutense University of Madrid, Madrid, Spain.
Optom Vis Sci. 2020 Nov;97(11):954-961. doi: 10.1097/OPX.0000000000001592.
While evaluating the tear-film breakup time, a careful set of precise instructions should be given to the subjects regarding the blink type because it substantially impacts the assessment of tear-film surface quality.
The purpose of this study was to determine to what extent the type of blink affects the tear-film breakup time and its assessment using two types of videokeratoscopes and the fluorescein test.
Thirty-three volunteers were assessed considering two different types of blinks: natural (short) and forced (unnaturally prolonged). Objective noninvasive breakup time estimation was performed using Oculus Keratograph 5M and Medmont E300, both equipped with tear-film analysis modules, followed by the fluorescein test. In addition, while overviewing videokeratoscopy recordings, noninvasive breakup time was assessed subjectively by one experienced observer marking the first noticeable distortion in the Placido-disk pattern. Statistical analyses included two-way ANOVA and paired-sample t test. The agreement between blinking and measuring modalities was assessed using Bland-Altman plots.
Forced blink significantly shortened the tear-film breakup time in all measuring modalities (two-way ANOVA, P = .003). The mean difference between breakup time after natural and forced blink was 3.2 (P = .002), 2.4 (P = .005), and 2.1 seconds (P = .002), for Keratograph 5M, E300, and fluorescein test, respectively. The group median of differences between objective and subjective noninvasive breakup time was less than 1 second with both videokeratoscopes. The objective noninvasive breakup time measured with Keratograph 5M was significantly longer than those with E300 and fluorescein test (both P < .001). No statistically significant difference was found between E300 objective assessment and fluorescein test (P = .19).
Forced blinks affect the assessment of tear-film stability. Hence, attention should be given in instructing the subjects before tear-film breakup time evaluation irrespectively to the method of measurement.
在评估泪膜破裂时间时，应该向受检者仔细说明眨眼类型，因为眨眼类型会极大地影响泪膜表面质量的评估。
本研究旨在确定眨眼类型在多大程度上影响使用两种角膜地形图仪和荧光素测试评估泪膜破裂时间。
对 33 名志愿者进行评估，考虑两种不同类型的眨眼：自然（短）和强制（不自然延长）。使用配备泪膜分析模块的 Oculus Keratograph 5M 和 Medmont E300 进行客观非侵入性破裂时间估计，然后进行荧光素测试。此外，在回顾角膜地形图记录的同时，一位经验丰富的观察者通过标记在 Placido 盘图案中首次出现的可察觉变形来主观评估非侵入性破裂时间。统计分析包括双因素方差分析和配对样本 t 检验。使用 Bland-Altman 图评估眨眼和测量方式之间的一致性。
强制眨眼在所有测量方式下均显著缩短了泪膜破裂时间（双因素方差分析，P=0.003）。自然眨眼和强制眨眼后破裂时间的平均差异分别为 3.2（P=0.002）、2.4（P=0.005）和 2.1 秒（P=0.002），分别为 Keratograph 5M、E300 和荧光素测试。两种角膜地形图仪的客观和主观非侵入性破裂时间之间的组中位数差异小于 1 秒。Keratograph 5M 测量的客观非侵入性破裂时间明显长于 E300 和荧光素测试（均 P<0.001）。E300 客观评估与荧光素测试之间未发现统计学差异（P=0.19）。
强制眨眼会影响泪膜稳定性的评估。因此，在评估泪膜破裂时间之前，无论测量方法如何，都应注意向受检者说明。
