Repeatability and Reproducibility of Tear Film Evaporation Rate Measurement using a new Closed-Chamber Evaporimeter

This study evaluates the repeatability and reproducibility of tear film evaporation rate measurement using a commercially available handheld closed-chamber evaporimeter (VapoMeter, Delfin Technologies, Finland).

This was a randomized observational study, in which two visits were required. At visit 1, screening tests were performed on the participants. Subsequently, tear evaporation was measured thrice by examiner 1 (E1). The procedure was then repeated by examiner 2 (E2) at visit 2.

40 healthy participants with no ocular diseases were recruited for this study. A closed chamber evaporimeter was used in this study (VapoMeter, Delfin Technologies, Finland). Primary investigations, including slit-lamp examination, tear production test, and ocular discomfort, were performed during the first visit for the purpose of screening.

The mean of the three measurements of tear evaporation obtained by examiner 1 at visit 1 was 19.38 ± 0.79 g/m²/h, and the mean of the three readings obtained by examiner 2 at visit 2 was 20.49 ± 0.48 g/m²/h. The average Intraclass Correlation Coefficient (ICC) among the three readings of tear evaporation was 0.84 and 0.63 with a 95% confidence interval (CI) at visits 1 and 2, respectively. A comparison of the reliability of the measurements from the two examiners revealed an ICC of 0.69 with a 95% CI.

The VapoMeter provides repeatable and reproducible measurements of tear film evaporation. This study demonstrates that the VapoMeter could provide clinicians with a readily available method for rapid evaluation of tear film evaporation. By considering the significance of tear evaporation as a diagnostic tool for dry eyes, the VapoMeter may help to diagnose better and manage dry eye syndrome.