Relative Stability of Regional Facial and Ocular Temperature Measurements in Healthy Individuals

Abstract

Purpose: Non-contact measurement of facial temperature using infrared thermography has been used for mass screening of body temperature during a pandemic. We investi-gated the relative stability of temperature measurement in different facial regions of healthy individuals. Methods: Twenty healthy subjects underwent two experiments. In the first experiment, subjects washed their faces with a 20°C wet towel for 1 minute. Temperature changes compared to baseline in the forehead, cornea, inner canthus, and outer canthus were determined using an infrared camera for 10 minutes. In the second experiment, lubri-cating eye drops at 20°C were instilled over one eye. Temperature changes in the same regions of interest were monitored for 5 minutes. Results: Baseline temperatures before face washing in the forehead and cornea, inner canthus, and outer canthus of the right eye were 33.4°C ± 0.8°C (mean ± SD), 33.3°C ± 0.8°C, 34.3°C ± 0.7°C, and 32.8°C ± 0.7°C, respectively. Reductions in temperature due to face washing were most significant for the forehead and least significant for the cornea. One minute after face washing, the corresponding changes were −2.8°C ± 0.6°C, −0.3°C ± 0.6°C, −0.6°C ± 0.7°C, and −0.9°C ± 0.7°C for the forehead, cornea, inner canthus, and outer canthus, respectively. After administering the eye drops, no significant temperature changes were observed. Conclusions: When facial temperature was exogenously cooled, the cornea had the most stable temperature readings. Translational Relevance: When using infrared thermography to screen facial tempera-ture, the measurement of corneal temperature is probably a better representative if the stability of temperature readings is critical.