Automated evaluation of parapapillary choroidal microvasculature in thyroid eye disease

The purpose of the study was to investigate the parapapillary choroidal microvasculature in thyroid eye disease (TED) using optical coherence tomography angiography (OCTA).

Only one eye of each subject was included in the study. Patients with TED and controls were included in the study. Participants were divided into three groups: control, inactive TED (ITED) and active TED (ATED). OCTA scans of the optic discs were obtained in a 4.5 × 4.5-mm rectangular area. Radial peripapillary capillary (RPC) density and peripapillary retinal nerve fibre layer (pRNFL) thickness were automatically calculated by the device software. Parapapillary choroidal microvasculature (PPCMv) density was automatically calculated using MATLAB software.

Forty-one patients with TED and 40 controls were included in the study. RPC density was significantly decreased in the ATED and dysthyroid optic neuropathy (DON) group compared to the controls and ITED group. There was significant increase in pRNFL in the ATED group. PPCMv density increased in the ATED group compared to the controls in whole ring area. The RPC density was significantly correlated with the TSHr Ab level (r < - 0.396, p < 0.001). Clinical activity score correlated positively with PPCMv density (r = 0.349, p = 0.001) but negatively with RPC density (r = - 0.321, p = 0.004).

Changes in peripapillary microvascular perfusion may play a role in the development of DON. As the severity of TED increases with clinical activity, so do the changes observed in peripapillary parameters. The decrease in RPC density may be due to compression caused by optic disc oedema, which may result in reduced blood flow. The increase in PPCMv density may be related to factors such as orbital congestion.