Disturbance in visual function can result from the hypoxia of altitude and the effects of cold.

High altitude eye problems: Disturbance in visual function can result from the hypoxia of altitude and the effects of cold. Hypoxia and a drying effect on the cornea from the increased evaporation of the tears,especially in windy conditions, can cause corneal swelling (edema). In normal eyes, this usually causes no visual disturbance though after corneal refractory surgery, refractory changes can occur. High altitude and hypoxia also affect the retina. Retinal hemorrhage is common but usually asymptomatic. However, if the macula is involved severe visual difficulties can occur.