Electrophysiologic studies in birdshot chorioretinopathy

We investigated retinal function in 16 patients with birdshot chorioretinopathy. Consistent abnormalities of dark adaptation, color vision, visual field, electro-oculography, electroretinography, and visual-evoked cortical potentials were found. They included raised thresholds of dark adaptation, acquired dyschromatopsia, mainly of the blue-yellow type, an electroretinogram with reduced amplitude, increased latency of the b-wave and absent oscillatory potentials, an abnormal electro-oculogram, and in many a marked disturbance in the pattern reversal visual-evoked cortical potential. The a-wave of the electroretinogram, the fast oscillations of the standing potential, and the flash visual-evoked cortical potential were well preserved. The nature of the abnormalities suggests that dysfunction was caused by inner retinal disease. Little evidence indicated outer retinal dysfunction resulting from choroidal inflammation.