Corneal Opacity in a Participant of a 161-km Mountain Bike Race at High Altitude.

Visual dysfunction is a relatively uncommon complaint among athletes during ultraendurance races. The pathophysiology of most of these cases is unknown. Corneal opacity has been speculated as the etiology for most of reported cases. We are presenting a case of a 56-year-old man with a partial unilateral corneal opacity and edema at kilometer 150 of a 161-km mountain bike race in high altitude. He was not able to finish the race (12-hour cutoff) because of his visual symptoms. He completely recovered in 3 days with no sequelae.