If only one eye gets cloudy after running or other exercise, especially if you get hot, you need to see a doctor.

“If one eye gets cloudy with exercise or increased body temperature, this could be a sign of Uhtoff’s phenomenon, which is associated with MS,” says Kaushal M. Kulkarni, MD, board certified ophthalmologist and neuro-ophthalmologist in private practice in New York.

Uhtoff’s phenomenon refers to the worsening of MS and some other neurological disease symptoms as a result of overheating from exercise (or hot tubs, saunas and fever).

“In MS, the myelin sheath around the optic nerve becomes thinned, which causes decreased conduction in the optic nerve,” says Dr. Kulkarni.

“With an increased body temperature, nerve impulses are either blocked or slowed down in a damaged nerve, but once the body temperature is normalized, signs and symptoms may disappear or improve.”

Can any condition other than MS cause one eye to become cloudy during or after running or other exercise?

Dr. Kulkarni says, “Any cardiovascular abnormality that leads to decreased blood flow to the eye could also get worse with exercise.

“These symptoms should be evaluated by an ophthalmologist or neurologist to determine the next steps.”

Dr. Kulkarni has a special interest in optic nerve regeneration.
Lorra Garrick has been covering medical, fitness and cybersecurity topics for many years, having written thousands of articles for print magazines and websites, including as a ghostwriter. She’s also a former ACE-certified personal trainer.