Abstract
Purpose :
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 single-center study based on data from the CO-BIRD prospective cohort. The main outcome measures were the best corrected visual acuity (BCVA) and the mean deviation (MD) evaluated by Humphrey 30-2 perimetry over the course of the disease. The disease duration was approximated by the time elapsed since the first symptoms and divided into 5-year periods spanning up to 30 years. If a patient had multiple visits during such a period, the middle visit was selected. Thereby, data from the same patient was not included more than once in any given 5-year period but was used over multiple periods if allowed by the duration of the follow-up.
Results :
The study included 447 Caucasian patients (181 males and 266 females), all of them HLA-A29 carriers. From onset to 30 years of disease duration, the number of patients in each 5-year period were 237, 250, 196, 147, 78 and 32 respectively. Overall, the spread of visual acuity and visual field results increased with disease duration. During the first 5 years after the disease onset, the median LogMAR BCVA was 0.00 (0.00—0.10) and later declined by a mean of 0.033±0.004 per 5-year period. By contrast, the median MD, which was initially -3.7 (-7—-1.4) dB, remained stable for 15 years, but decreased by a mean of -2.27±0.35 dB per 5-year period thereafter. On a per eye basis, the deficits of BCVA and MD correlated more strongly with increasing disease duration as indicated by a rise in the Pearson correlation coefficient from 0.14 at onset to 0.49 after 25 years. In each period, the between-eye correlation of MD was stronger than that of BCVA.
Conclusions :
BSCR resulted in a large heterogeneity of visual outcomes which increased over the duration of the disease. Central vision loss was gradual from the onset of BSCR symptoms, whereas peripheral vision within 30° decreased primarily after 15 years. The correlation between central and peripheral vision measurements increased over time. The between-eye symmetry of peripheral visual field loss was greater than that of central visual acuity loss. Our data provides a global overview of the visual consequences of BSCR as a function of disease duration.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.