Analysis of Ocular Surface Temperature in Patients with Dry Eye

Abstract Background: Ocular surface temperature (OST) has been widely investigated using the principle of recording the infrared radiation (IR) emitted by the ocular surface.OST changes have been reported in different ocular diseases, such as glaucoma, choroidal abnormalities, and dry eye. Aim of Study: The objective of this study was to investigate the relationship between tear film evaporation rate and ocular surface temperature in patients with mild to moderate dry eye. Material and Methods: Twenty-five patients with dry eye (average age, 42.61±9.77 years) were recruited for this study. An infrared camera was used to measure the ocular surface temperature. The geometric center of the cornea was estimated manually by drawing a circle with approximately 4-mm diameter at its center, and the mean temperature of this circle area was calculated. Thermal images of the ocular surface were continuously recorded for 60 seconds at a frame rate of 30Hz. The tear film evaporation rate was determined using a handheld closed chamber evaporimeter. Three measurements were obtained; then, the average value was calculated. Results: The measured ocular surface temperature was lower in the dry eye group (33.74±0.058ºC) than in the control group (33.92±0.57ºC). The tear evaporation rate was signifi-cantly greater in patients with dry eye (77.37±23.07) than in the control group (49.53±15.36g/m2/h). Conclusion: This study demonstrates that the ocular surface of patients with dry eye is cooler compared to that of healthy individuals (<0.2ºC). The significantly increased tear film evaporation rate may explain the reduction in ocular surface temperature (OST) among patients with dry eye.