Thermal Imaging of the Ocular Surface in Thyroid Eye Disease: A Comparison between Active, inactive and Healthy Eyes

Aim: To report the temperature differences on the ocular surface using infrared thermal imaging (TI) in thyroid eye disease (TED) and healthy eyes Methods: Prospective, consecutive, comparative case series comparing TI parameters between active and inactive TED with healthy controls. The data captured included baseline demography, activity of TED and the TI parameters. Area under the receiver operating characteristic curves (AUROC) were calculated for the temperature values to determine the sensitivity and specificity in distinguishing active from inactive TED. The Youden index and the predictor cut off values were also reported. Results: The study included 11 eyes with active TED, 46 eyes with inactive TED and 40 eyes healthy patients. Temperatures of pre-determined points on the ocular surface in degrees were compared between the three groups. Temperature at the caruncle, medial and lateral conjunctiva was noted to be significantly higher in the active TED group compared to inactive TED and healthy eyes. The most favorable Youden index (0.7) was noted for the caruncle with an AUROC value of 0.91, a sensitivity of 91% and a specificity of 79%. Correlation coefficient for the caruncular temperature with the corresponding CAS (clinical activity score) was 0.65 (95% C.I. 0.45 to 0.78, p < .0001). Conclusion: Thermal imaging in TED is an objective way of documenting surface inflammation by the surrogate marker of temperature change. It supplements CAS in clinically evident cases and could be useful in staging eyes with subtle clinical signs as well as those where signs have reduced following initiation of treatment.