Visual acuity and visual field as a function of disease duration in patients with birdshot chorioretinitis.

Background: Birdshot chorioretinitis (BSCR) is a chronic bilateral posterior uveitis, which can affect central as well as peripheral vision. The aim of this study was to assess how visual acuity and visual field evolved over time in patients with BSCR.

Methods: This was a prospective, observational, single-centre study based on data from the CO-BIRD cohort. Patient visits were categorised based on the time elapsed since the first symptoms, and groups of patients with different disease duration were defined. The main outcome measures were the best corrected visual acuity (BCVA), the mean deviation (MD) and the standard pattern deviation (PSD).

Results: The study included 447 Caucasian patients (181 males and 266 females), all of whom HLA-A29 carriers. From onset to 30 years of disease duration, the number of patients in each consecutive 5-year period was 237, 250, 196, 147, 78 and 32, respectively. Overall, the range of visual acuity and visual field results increased with disease duration. BCVA gradually decreased and showed a significant decline after 11-15 years after the first symptoms. Among the visual field indices, PSD significantly increased after 16-20 years, while MD showed a significant decline after 21-25 years. No major gender differences were found in visual outcomes, indicating comparable severity. The intereye correlations of MD and PSD were stronger than those of BCVA.

Conclusions: BSCR resulted in a large heterogeneity of visual outcomes, which increased with time. Our data provide an overview of the visual consequences of BSCR as a function of disease duration.