Inter-week variation of meibometry and tear break-up time in healthy subjects

Clinical relevance: Variation with time in the tear film parameters should be considered by the clinician since measurements are made can influence proper diagnosis. Background: A hallmark of dry eye is an unstable tear film associated with variability in objective daily measures. The purpose of the present study was to evaluate the inter-week repeatability of meibometry, break-up time (BUT) and maximum blink interval (MBI) in healthy subjects. Methods: Forty healthy subjects were recruited for the study. Meibometry, BUT and MBI were performed twice in two sessions, one-week apart. Meibum from the lower eyelid was collected and quantified with the Meibometer MB550. Five meibomian curves were generated by tape and each peak value was averaged as a mean value per session. BUT and MBI were determined three times after fluorescein instillation and recorded by a DV-3 camera attached to the slit lamp. BUT and MBI videos were analysed by a second masked observer. Both BUT and MBI values were calculated by averaging the two most similar measurements of the three evaluated. Results: No statistical difference between inter-week sessions was obtained for the meibometry (p > 0.340; Wilcoxon test), BUT (p > 0.326; Wilcoxon test) and MBI values (p ≥ 0.248; Wilcoxon test). Inter-week differences were low for BUT and MBI when time intervals were no longer than 15 seconds (both p ≥ 0.586; Wilcoxon test). A correlation between BUT and MBI was found (r ≥ 0.668, p < 0.001; Spearman Rho), while no statistical correlation was obtained between meibometry results and BUT or MBI (all p ≥ 0.194; Spearman Rho). Conclusion: Meibum secretion and the tear film stability present good intersession repeatability, and are stable along with sessions in healthy patients.This study was funded by the Spanish Ministry of Science and Education and the Institute of Health Carlos III (ISCIII) through research project [PI10/01098].S