Correlations among ocular surface temperature difference value, the tear meniscus height, Schirmer's test and fluorescein tear film break up time

Purpose To report the use of a thermographer for measuring ocular surface temperature, and to evaluate the correlation among the obtained temperature difference values (TDVs) and dry eye parameters (tear meniscus height (TMH); Schirmer's test results; fluorescent tear breakup time (FTBUT)). Methods Forty-three participants (age 40.2 ±14.7 years; range 21-67 years) from Far Eastern Memorial Hospital, Taiwan were recruited for the study. The surface temperature was measured at the centre of the ocular surface for 4 s after blinking. TDV was defined as the change in corneal surface temperature relative to that of the preceding eye opening, where TDV01, TDV02, TDV03, and TDV04 represent the values obtained 1, 2, 3, and 4 s after blinking, respectively. Anterior segment optical coherence tomography (AS-OCT) was employed to measure the lower TMH. Schirmer's test with topical anaesthetic was conducted to measure the basal tear secretion. The FTBUT was recorded using a digital camera. Results TDV measurement exhibited high reliability (intraclass correlation coefficient=0.91). TDV03 exhibited the highest significance and strongest positive correlation with the TMH (r=0.52, p=0.0003) and Schirmer's test value (r=0.39, p=0.008), whereas the TDV03-FTBUT correlation was non-significant. Age correlated negatively and significantly with the TDV (r=-0.35, p=0.021), TMH (r=-0.33, p=0.031), and Schirmer's test value (r=-0.31, p=0.044). TDV03 remained significantly correlated with the TMH and Schirmer's test value after adjustment for age. Conclusions The thermographer was effective in capturing temperature changes in the ocular surface. The temperature difference 3 s after blinking appears to be correlated with lower TMH and Schirmer test values.