Longitudinal cohort study of patients with birdshot chorioretinopathy. IV. Visual field results at baseline.

To describe visual field parameters at baseline examination of 80 participants in a longitudinal cohort study of birdshot chorioretinopathy and to identify relationships between these parameters and visual acuity, symptoms, clinical findings, and results of laboratory tests. Single-center cross-sectional study. Standardized Fastpac, full-threshold Humphrey 30-2 (Carl Zeiss Meditec, Dublin, California, USA) visual field studies were performed for both eyes of all patients. A standardized protocol identified foveal threshold and mean deviation, specified categories of total deviation, and assigned visual field pattern descriptors. These parameters were compared with best-corrected visual acuity (BCVA), symptoms, color confusion score (CCS), cataract, vitreous inflammatory reactions, retinal vasculitis, birdshot lesion characteristics, and ocular coherence tomography (OCT) and fluorescein angiography parameters. Each visual field parameter was closely related to the others, although mean deviation could be abnormal in the presence of a near normal foveal threshold. Mean deviation was related to BCVA, but the correlation was moderate (the Spearman correlation, -0.55; P < .001). It was also related to CCS and the symptoms of blurry vision, poor contrast sensitivity, and nyctalopia. The most common visual field patterns were multiple foci and arcuate defects. Among clinical and laboratory findings, visual field parameters were most closely related to absence of the third highly reflective band on OCT (P < .001). Patients with birdshot chorioretinopathy may have a variety of visual field abnormalities, even with normal BCVA. Abnormalities seem to be associated with retinal damage. Automated visual field testing may provide objective measures for monitoring disease activity.