Choroidal Findings in Eyes With Birdshot Chorioretinitis Using Enhanced-Depth Optical Coherence Tomography

The purposes of this study were to describe choroidal findings observed using optical coherence tomography with enhanced depth imaging (EDI-OCT) in eyes with birdshot chorioretinitis (BSCR) and to test the hypothesis that these findings are related to participant demographics, clinical characteristics, and treatment.

In a multicenter, cross-sectional study, 172 eyes of 86 individuals with BSCR underwent a standardized clinical evaluation, including defined protocols for EDI-OCT imaging, with macular and peripapillary volume scans. Choroidal findings were compared to demographic information, ophthalmic examination findings, and treatment history, using logistic regression models. EDI-OCT images were evaluated by two independent, masked graders.

Median age was 56 years old; 54 participants (62.8%) were female. One or more choroidal lesions (a predefined hyporeflective zone) were identified in 105 eyes (63.6%). Median choroidal thickness was 293 μm. Choroidal lesions were associated with longer disease durations (odds ratio [OR]: 1.08; P = 0.03), increased vitreous haze (>0.5+; OR: 4.43; P = 0.02), presence of macular edema (OR: 3.00; P = 0.02), and thick choroids (OR: 3.89; P = 0.001). Use of immunomodulatory therapy was associated with lower risk of thin choroids (lower 25th percentile, OR: 0.17; P = 0.001) or thick choroids (upper 25th percentile, OR: 0.22; P = 0.002). At least some choroidal lesions did not have corresponding, clinically apparent "birdshot lesions" on fundus examination.

Choroidal abnormalities identified by EDI-OCT imaging are common in the macular and peripapillary regions of eyes with BSCR. Choroidal lesions were associated with clinical signs of inflammation, suggesting that they represent foci of disease activity. EDI-OCT may provide useful information about disease mechanisms and response to treatment in future, longitudinal studies of BSCR.