Retinal branch vessel occlusion in acute intermittent porphyria

Three patients with acute intermittent porphyria were noted to have retinal branch vessel occlusion. Branch "vein" occlusion, segmental optic atrophy, and soft exudate were the most common ocular manifestation. Two patients had labile elevated hypertension. When patients present with retinal branch vessel occlusion and a constellation of bizarre symptoms that might include hypertension, abdominal pain, acute psychotic behavior and/or cutaneous photosensitivity, the diagnosis of acute intermittent porphyria should be considered.