To evaluate corneal endothelial cell morphology in patients with thyroid-associated ophthalmopathy (TAO).

Seventy-two eyes of 36 patients with TAO presenting to the ophthalmology department between January 2018 and January 2022 were included in the study. The findings were compared with 98 eyes of 49 healthy individuals. Mean endothelial cell density (ECD), coefficient of variation (CV), maximum cell area, minimum cell area, average cell area, and hexagonality ratio were obtained using non-contact specular microscopy. The thicknesses of peripapillary retinal nerve fiber layer (RNFL) and macular ganglion cell complex (GCC) were measured using optical coherence tomography (OCT).

The TAO group consisted of 36 patients, 11 (30.6%) men and 25 (69.4%) women, and the control group of 49 healthy individuals, 14 (28.6%) men and 35 (71.4%). No significant differences were determined between the TAO and control groups in terms of the specular microscopy findings of mean ECD, CV, or hexagonality ratio values (p > 0,05). However, the mean Hertel values differed significantly between the two groups (p = 0.001).

When the TAO group was divided into two subgroups based on patients who had previously received prednisolone therapy and those who had not, significant differences were observed in terms of mean ECD, CV, and hexagonality ratio values (p > 0.05).

Comparison of patients diagnosed with active TAO and receiving prednisolone therapy and the TAO patients with inactive disease revealed lower ECD, higher CV values, and lower hexagonality ratios in the prednisolone therapy group. These findings all suggest that inflammation in patients undergoing active disease affects the corneal endothelium.