Longitudinal cohort study of patients with birdshot chorioretinopathy. I. Baseline clinical characteristics

Abstract

Purpose: To describe baseline clinical characteristics of a cohort of 80 patients with birdshot chorioretinopathy in anticipation of a longitudinal study, and to identify relationships between visual acuity, symptoms, and ophthalmic findings.

Design: Single-center cross-sectional study.

Methods: A standardized examination was performed in the same order on a single day for each patient. A grading system for birdshot lesions was established prospectively to evaluate the following lesion characteristics: quantity, distribution, morphology, and pigmentation. Relationships between clinical features of disease were sought in multivariate analyses that adjusted for age, duration of uveitis, and treatment.

Results: Mean age at baseline examination was 55.6 years. Median best-corrected visual acuity (BCVA) was 0.8 (range, counting fingers to 1.2). There were no relationships between BCVA and any birdshot lesion characteristic. The most common cause of BCVA < or =0.4 was macular edema. Visual symptoms were present in 78 patients (97.5%), including 17 (94.4%) of 18 patients with BCVA > or =1.0 in both eyes. Blurred vision was associated with decreased BCVA (P = .02) and macular edema (P = .022). Increased lesion pigmentation was associated with complaints of blurred vision (P = .030), vibrating vision (P = .011), and nyctalopia (P = .056).

Conclusions: Symptoms are common in patients with birdshot chorioretinopathy, even among those with good BCVA. Lesion pigmentation may be a marker of decreased visual function that is not reflected in central visual acuity. These findings highlight the limitation of using visual acuity measurements for monitoring patients with birdshot chorioretinopathy and as an outcome measure for studies of this disease.