Impact of environmental adaptation on tear film assessments

Purpose. - The purpose of this study was to investigate the effect of ocular environmental adaptation on clinical tear film assessment. Method. - Thirty subjects (male, mean age 23 +/- 2.5) participated in this study. A number of clinical tear film tests were applied, including: fluorescein tear break-up time (FTBUT), Schirmer test and tear prism height test (TPH). The tear physiology of each subject was evaluated twice, once immediately when they arrived from the external environment, and then after 30 minutes adaptation in the exam room environment. Results. - The mean values were: Schirmer test A (22.1 +/- 2.99), Schirmer test B (24.2 +/- 2.63), FTBUT A (8.00 +/- 1.94), FTBUT B (9.13 +/- 2.04), TPH A (0.179 +/- 0.026) and TPH B* (0.187 +/- 0.023). Statistical testing using Witcoxon-signed rank test showed a significant difference between the Schirmer test results measured at the different times (P = 0.008). Also, the FTBUT and tear prism height test results showed significant differences between the two evaluation times, (P = 0.081, 0.011, respectively) (A: tear assessed when the subject comes from the outside environment, B: tear film assessed after 30 min adaptation in the clinical environment). Conclusion. - This study showed a significant difference between the tear film test results evaluated when the subjects were assessed immediately from the outside environment and after an adaptation time in the clinic environment. Practitioners must consider the effect of differences between external and clinical environment adaptation on clinical tear film physiology. (C) 2018 Elsevier Masson SAS. All rights reserved.