Characterization of Retinal Microvascular Abnormalities in Birdshot Chorioretinopathy Using Optical Coherence Tomography Angiography

Abstract

Purpose : We performed a retrospective, observational, single-center study to characterize changes in the retinal microvasculature in eyes with birdshot chorioretinopathy (BCR) using optical coherence tomography angiography (OCTA).

Methods : This study included 53 eyes from 28 patients with a diagnosis of BCR and 110 eyes from 59 age-matched controls. En-face OCT angiograms of the superficial capillary plexus (SCP) and deep capillary plexus (DCP) of each eye were used to assess for the presence of microvascular abnormalities and for extracting vessel analysis measures including vessel area and foveal avascular zone (FAZ) area. A multivariable analysis was performed to identify factors associated with each computed vessel analysis parameter. Further longitudinal analysis was performed among a representative cohort of 23 BCR eyes from 16 patients at baseline and at a two-year timepoint. Quantitative parameters for vessel analysis including whole-image vessel density (VD, %), extra-foveal avascular zone (extra-FAZ) VD (%), and FAZ area (%) were evaluated between control and BCR eyes.

Results : In the SCP and DCP, whole-image VD and extra-FAZ VD were lower in the BCR group compared with controls (P < 0.0001), while in the DCP, FAZ area was lower in controls (P = 0.0008). In the SCP and DCP, increasing logMAR (worse BCVA) was significantly associated with a decrease in whole-image and extra-FAZ VD (SCP: P < 0.0001; DCP: whole-image VD [P = 0.0046] and extra-foveal VD [P = 0.0049]). Multivariable analysis, with vessel analysis parameters as outcomes, demonstrated that in the DCP, increasing age, increasing disease duration, lower CST, and treatment-naïve eyes (compared with those on only biologics) demonstrated a significant decrease in both whole-image and extra-FAZ VD. In the SCP, longer disease duration was associated with a significant decrease in both whole-image and extra-FAZ VD. Finally, longitudinal analysis demonstrated no significant difference in any vessel analysis parameters except for a significant increase in DCP FAZ area.

Conclusions : Quantifying VD in the retinal microvasculature may be a useful prognostic biomarker for monitoring disease progression in patients with BCR. Further studies with extended longitudinal follow-up are needed to characterize its utility in monitoring disease progression and treatment response.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.