Anterior segment optical coherence tomography angiography in the evaluation of thyroid eye disease: a pilot study

Current grading systems for thyroid eye disease (TED) are subjective, highlighting the need for objective assessment tools. This pilot study evaluated whether anterior segment optical coherence tomography angiography (AS-OCTA) can detect characteristic vasculature changes in TED. A prospective comparative case series at Moorfields Eye Hospital included patients with TED and healthy controls. AS-OCTA images were captured using the AngioVue system, and masked-image analysis quantified the vessel density index (VDI) and fractal dimension (FD). Twenty-nine TED patients (58 eyes) and 13 controls (26 eyes) were included. In total, 965 images were analysed (671 TED, 294 controls). Mean VDI was significantly higher in TED patients (33.3%) than in controls (20.7%) (p = 0.01). Highest VDI occurred in the conjunctival/episcleral complex in both groups. TED patients had higher episcleral/scleral VDI than conjunctival epithelium; the inverse was observed in controls. Active TED (CAS = 3-7) exhibited the highest VDI versus inactive TED (CAS = 0-2) and controls. FD was higher in TED, increasing progressively from controls to inactive and active TED. Four patients (6 eyes) underwent decompression surgery with non-significant reductions in VDI and FD. AS-OCTA detects significant differences in vascular parameters between TED and healthy controls, supporting its potential as a non-invasive, quantitative adjunct in TED grading systems.