Manual interferometric device for routine non-invasive tear film break-up time assessment

Purpose: To determine the feasibility of non-invasive tear break-up time (NIBUT) assessment using the Handheld tear lipid layer thickness assessment instrument and compare it with the standard tear break-up time (TBUT) test and other dry eye tests.Subjects and methods: 108 subjects were enrolled, 56 with and 52 without dry eye symptoms. Schein questionnaire was used to determine the severity of dry eye symptoms. Ocular signs were assessed by NIBUT, TBUT, lipid layer thickness (LLT), lid-parallel conjunctival folds (LIPCOF), conjunctival hyperemia, and corneal staining.Results: Median NIBUT and TBUT, and other clinical test values significantly differed among the dry eye symptoms group and control group. NIBUT yielded the most significant difference between the groups (NIBUT: 7 sec vs. 17.5 sec, p < .001, Z = 5.94; TBUT: 5 sec vs. 10 sec, p < .001, Z = 4.38; LLT: p = .007; LIPCOF: p < .001, conjunctival hyperemia: p < .047, corneal staining: p < .010). Spearman's test showed a significant correlation between NIBUT and TBUT (p < .001), NIBUT and LLT (p = .001), NIBUT and LIPCOF (p = .019), NIBUT and conjunctival hyperemia (p = .002), and NIBUT and corneal staining (p = .012) in the dry eye symptoms group. NIBUT did not significantly differ among the three measurements in both groups of patients (p = .061, p = .096), while TBUT values did in the control group (p < .001). Short NIBUT values were the main predictors and indicators of dry eye complaints (AOR = 0.87, p < .001), superior to TBUT (AOR = 0.88, p = .008) and other tests even after adjustment for age and gender.Conclusion: NIBUT measured by Handheld instrument is a simple, accessible, practical, and, most of all, reproducible and objective method that might allow NIBUT assessment on a regular basis.