Preretinal arterial loops and retinal arterial occlusion.

A 19-year-old man had bilateral congenital preretinal arterial loops emerging from the optic disk into the vitreous cavity. The loop in the right eye was associated with an inferior papillary arterial occlusion. Extensive examination to determine a systemic cause of the occlusion was negative; twisting or kinking of the loop may have had a role. The major arterial blood supply in each eye was cilioretinal in origin and in the left eye, the inferior preretinal arterial loop supplied blood to both the retina and the choroid. In three previous cases and our case of preretinal arterial loops associated with branch retinal arterial occlusion, none had emboli or associated systemic factors. All involved solely arterial supply to the inferior retina. The ages of three of the four patients ranged from 19 to 22 years.