Microvascular and Structural Characterization of Birdshot Chorioretinitis in Active and Inactive Phases.

Objective: This study aimed to examine microvascular changes and identify predictors of short-term quiescence in active birdshot chorioretinitis (BSCR). Methods: An observational, prospective, 12-month follow-up cohort study was conducted. BSCR eyes were clinically assessed at baseline, categorized as active or inactive, and reevaluated at 12 months. Based on their clinical activity at both timepoints, eyes were divided into three subgroups: active-to-inactive (A-I), consistently active (A-A), and consistently inactive (I-I). Structural OCT, OCT-angiography (OCT-A), and ultra-widefield imaging were utilized. Exam data from fundus and nasal subfields were analyzed for microvascular changes and quiescence predictors. Results: Sixty eyes from 30 BSCR patients (47% women, 53% men, mean age 59.7 ± 12.3 years) were included. In the A-I group (16 eyes), vascular density and perfusion indices increased in all subfields post-quiescence, contrasting with the other groups. Perifoveal looping in the superficial capillary plexus predicted quiescence at 12 months compared with the A-A group. Conclusions: Vascular density rises after complete inflammation control in BSCR, and perifoveal capillary loops serve as potential predictors of short-term quiescence in active BSCR.