Repeatability of infrared ocular thermography in assessing healthy and dry eyes

To investigate the inter-image, inter-occasion and inter-examiner repeatability of NEC infrared thermo-tracer TH 9260 in assessing healthy and dry eyes.

Ocular surface temperature (OST) was recorded using NEC infrared thermo-tracer TH 9260 on 21 healthy and 15 dry eyes. Data from the right eyes were analyzed. Marking of the ocular surface and OST acquisition was performed using a new 'diamond' demarcation method. Twelve OST indices were obtained at three different time points following a blink: 0s, 5s and 10s. Inter-image, inter-occasion and inter-examiner repeatability of the infrared ocular thermography was evaluated by calculating coefficients of repeatability (COR).

Ten out of the twelve tested OST indices had good repeatability with small inter-image variability (%COR: 0.2-0.9), inter-occasion variability (%COR: 2.1-3.7) and inter-examiner variability (%COR: 1.5-3.7) for the three studied time points. Two of the OST indices (temperature standard deviation of the region of interest and radial temperature difference) had poor repeatability with much larger inter-image variability (%COR: 8.9-140.7), inter-occasion variability (%COR: 47.5-153.5) and inter-examiner variability (%COR: 54.7-142.0) for the three studied time points.

Most of the metrics adopted in this assessment can be considered to be highly repeatable.