Disc edge veins of Kraupa: rare exit anomalies of the retinal vein.

Disc edge veins of Kraupa are anomalies of the retinal venous system in which blood flows from the retina through a single venous trunk at or near the edge of the disc instead of at its centre. We report two examples of patients with these anomalies and illustrate the appearance of the anomalies with fundus photographs and a fluorescein angiogram. In one patient the retinal vein exited the eye through the sclera at the margin of the optic disc; in the other it disappeared into the disc tissue near the disc margin.