Normalized ocular surface temperature models for tear film characteristics and dry eye disease evaluation

To construct normalized ocular surface temperature (NOST) models for different tear film characteristics and evaluate its potential in dry-eyes screening. We included 227 right eyes of 227 patients. Tear film characteristics were categorized into 4 types according to fluorescein tear film breakup time (FTBUT) and Schirmer test results, namely type 1: FTBUT >5 s and Schirmer >5 mm; type 2: FTBUT ≤5 s and Schirmer >5 mm; type 3: FTBUT ≤5 s and Schirmer ≤5 mm; and type4: FTBUT >5 s and Schirmer ≤5 mm. Ocular surface temperature was measured by a video-thermographer. Mean temperatures of the central cornea were calculated from the videos of each frame during the 4-s blink interval. We first constructed individual NOST model for every tear characteristic. Participants were included for further analysis when their OSDI was ≥23, FTBUT ≤5 s, and Schirmer >5 mm. They were subdivided into short-BUT and short BUT with SPK subgroups according to the absence or presence of corneal fluorescein-stain. The NOST models of the normal, short-BUT and short BUT with SPK groups were separately constructed and the potential of screening analyzed via ROC curves. Each tear film type had a different NOST model. At 3 s after blinking, the order of NOST was type 4 >type 1 >type 3 >type 2. In dry-eye screening, the NOST was normal > short-BUT > short BUT with SPK. The NOST displayed a sensitivity 0.87, specificity 0.80, and AUC 0.88 for diagnosing short BUT with SPK. NOST models are useful in differentiating tear film characteristics and screening dry-eyes. It alleviates the discomfort and inconvenience encountered during conventional dry-eye diagnosis.