High-altitude retinopathy.

Thirty-nine healthy subjects were examined before and after a stay at 5,360 m by ophthalmoscopy and by retinal photography. Twenty of them were also tested for visual acuity, scotomata, and capillary leakage. Vascular engorgement and tortuosity and disc hyperemia were seen in all subjects at altitude and are a "normal" response to hypoxia. Twenty-two (56%) of the subjects had retinal hemorrhages and one showed "cotton-wool spots". These changes are abnormal reactions and are considered high-altitude retinopathy. After maximal exertion on a cycle ergometer, fresh hemorrhages were observed in seven of 34 subjects. The incidence of hemorrhage associated with exercise was significantly greater than predicted. Fluorescein leakage was noted after exercise in eight of 20 persons tested and was associated with exercise-induced hemorrhages. Two persons developed premacular hemorrhages.