Subfoveal serous retinal detachment associated with extramacular branch retinal vein occlusion

PURPOSE: To study the pathophysiology of subfoveal serous retinal detachment (SRD) observed in eyes with extramacular branch retinal vein occlusion (BRVO). METHODS: We retrospectively reviewed the medical records of nine patients (nine eyes) with extramacular BRVO with macular complications that were examined using optical coherence tomography (OCT). RESULTS: Extramacular BRVO was observed in the inferior area in three eyes, in the superior area in five eyes, and in the nasal area in one eye. Visual acuity was moderately disturbed (median, 0.6; range, 0.2–0.9, measured using the Landolt chart). One eye showed extensive SRD that was connected to the area affected by BRVO through the subretinal space. In eight of the eyes, focal SRD was observed beneath the fovea without subretinal connections to the area affected by BRVO. However, all these eyes showed marked retinal swelling in the outer retina, particularly in the outer plexiform layer. In two of the eyes, detailed OCT examinations showed a small break on the external surface of the retina connecting the swollen outer retina with the underlying SRD. All eyes showed hyperreflective foci in the outer retina, most frequently along the inner boundary of the outer plexiform layer and external limiting membrane. CONCLUSION: Extramacular BRVO is often accompanied by focal SRD beneath the fovea. Leakage from the retinal capillaries affected by BRVO travelled via the outer plexiform layer and caused SRD under the fovea.