Comparison of non-invasive and fluorescein tear film break-up time in a 65-year-old Norwegian population: a cross-sectional study.

Abstract

Measurement of tear film stability is central in dry eye disease (DED) diagnosis. In this study, we aimed to compare the performance of two methods of tear film stability measurement: non-invasive tear break-up time (NIBUT) and fluorescein tear film break-up time (FTBUT). Cross-sectional study. The study involved 132 subjects of 65-year-old inhabitants of the Oslo region who were not seeking ophthalmic care. The participants underwent a battery of DED tests, including NIBUT measured on Oculus Keratograph 5M and a traditional method using fluorescein drops (FTBUT). Oculus Keratograph 5M measures two types of NIBUT:; appearance time of the first dry spot (NIBUT_First) and average NIBUT_Avg. 74 participants (56%) were female and 58 were male (44%). Subjects presented with varying degrees of DED signs and symptoms. Mean values of NIBUT_First and FTBUT from all the participants were significantly different (6.2±4.9 s vs 8.6±6.2 s, p<0.0001). There was also a significant difference between NIBUT_First and NIBUT_Avg values (6.2±4.9 s vs 8.3±5.5 s, p<0.0001). In contrast, no difference was observed between FTBUT and NIBUT_Avg values (8.6±6.2 s vs 8.3±5.5 s, p=0.655). The receiver operating characteristic curve analysis was performed to compare NIBUT and FTBUT in regards to other clinical tests (Ocular Surface Disease Index, ocular surface staining, blink interval, eye redness, corneal sensitivity, lid debris, Schirmer I test, tear osmolarity, meibum quality, meibum expressibility, lid hyperemia, tear meniscus height,. irregular lid margin, conjunctival hyperaemia, margin telangiectasia, lipid layer and meibomian gland drop-out). While FTBUT demonstrated results with area under the curve>0.6, neither NIBUT_First nor NIBUT_Avg showed significant results. NIBUT_First was shorter than FTBUT. Low correlation between NIBUT and FTBUT indicates that these diagnostic tests are not interchangeable. Other DED tests had correlation, though low, while NIBUT did not demonstrate correlation.