Non-invasive method of monitoring retinal vasculitis in patients with birdshot chorioretinopathy using optical coherence tomography

Background/aims To investigate the utility of using montaged optical coherence tomography (OCT) thickness maps to monitor perivascular thickness as a marker of vasculitic activity in patients with large-vessel retinal vasculitis. Methods This is a retrospective cohort study of 22 eyes of 11 patients with a history of retinal vasculitis associated with birdshot chorioretinopathy (BCR). Patients had serial spectral domain 6x6mm cube OCT scans centred on the fovea, optic nerve and proximal branches of the superior and inferior retinal vessels. OCT thickness change maps for each respective region were analysed. Changes in perivascular thickness were confirmed by assessing vasculitic activity on fluorescein angiography (FA), when clinically indicated. Results In three patients, montaged OCT scans were acquired at diagnosis and serially through initial treatment. In all three patients, montaged OCT demonstrated reduced perivascular thickening with oral prednisone treatment, which was confirmed by FA showing reduced vascular leakage in both eyes. Eight patients had serial montaged OCT scans after diagnosis and initial treatment of BCR. Four of these patients showed fluctuations in perivascular thickness during flares and treatment that were confirmed by either increased or decreased vascular leakage on FA. The other four patients remained quiet on their immunosuppressive treatment regimens, and no changes in perivascular thickness were detected. Conclusions Evaluating large-vessel perivascular thickness on OCT scans may be a useful method for non-invasively monitoring posterior pole large-vessel retinal vasculitis.