Evaluation of peripapillary vascular flow in patients with Thyroid-Associated Ophthalmopathy (TAO) by OCT Angiography

Purpose: To evaluate changes in peripapillary vascular blood flow indices (PVBFI) in patients with thyroid-associated ophthalmopathy (TAO) using OCT angiography (OCTA) technology. Methods: Patients with TAO and control subjects matched for age and sex were included in the study. Eye examination, Clinical Activity Score (CAS) evaluation and OCTA scan analysis (Topcon ImageNet 6; DRI OCT Triton, Topcon Corporation) were performed. In particular, PVBFI of the superficial capillary plexus (SCP), deep capillary plexus (DCP), outer retina (OR) and choriocapillaris (CC) layers were obtained by OCTA and extracted from 8-bit greyscale OCT images using the ImageJ software package. Results: Twenty-six patients with TAO (19 females, mean age 54.7 ± 5.2 and 7 males, mean age 51.4 ± 16.3) were compared with 26 healthy subjects (15 females, mean age 48.2 ± 14.1 and 11 males, mean age 53.1 ± 15.2). Both DCP-PVBF and CC-PVBFI were significantly reduced in TAO patients compared to control eyes (28.6 ± 2.1 vs. 29.7 ± 0.93, p = 0.002; 46.5 ± 1.72 vs. 47.2 ± 1.2, p = 0.019 respectively); on the other hand, no statistically significant differences were found in SCP-PVBFI and OR-PVBFI in TAO patients compared to healthy subjects (p > 0.05). Also, CC-PVBFI was associated with elevated values of CAS (p = 0.018) and ROC curve showed that patients with elevated CC-PVBFI were correlated with active TAO (CAS > 3) (p = 0.012). Conclusions: TAO disease may be associated with changes in DCP-PVBFI and CC-PVBFI; also, CC-PVBFI seems to correlate with disease activity.