Eye function and physiology following a 161-km foot race

Significant visual impairment occurs in a small percentage of ultramarathon participants and is thought to be due to corneal edema. Yet, the usual effects of prolonged exercise on the eye have not been previously reported. Eight study volunteers who completed the 161-km Western States Endurance Run underwent pre-race and post-race binocular and monocular visual acuity, intraocular pressure, and corneal thickness measurements. None was symptomatic with visual impairment during the race and they demonstrated no changes from pre-race to post-race in visual acuity (p = 0.11-0.95 for right, left and combined), intraocular pressure (p = 0.11-0.43 for the both eyes) and corneal thickness (p = 0.30-0.99 for both eyes at three corneal areas). We conclude that there is no evidence that ultramarathon running has an acute effect on eye function or physiology when the runner has no symptoms or findings of visual impairment.