Q. Is it normal to get blurred vision when exercising?
A. Matthew Gardiner, director of ophthalmology emergency services at the Massachusetts Eye and Ear, says that some people occasionally experience visual changes during exercise, but it’s not a common complaint and should not happen often in people who are healthy. “The eye needs oxygen and it needs fuel,” he says, both of which depend on blood flow. “Alterations can certainly cause blurry vision,” he says, but the blood vessels in the eye are usually able to regulate blood flow in a way that keeps your vision normal as you exercise.
A temporary vision change while exercising could simply be a sign that you didn’t eat enough that day and have low blood sugar or low blood pressure. Environmental factors can also be a cause: Vision can blur when eyes are dry from running in the cold or wind, or irritated from sweat and sunscreen.
But if blurred vision happens frequently without an obvious cause, Gardiner says it’s worth getting checked out by a doctor as it could be a sign of an underlying health problem. Visual disturbances during exercise are sometimes a feature of migraines, and they are associated with some rarer health conditions as well. Certain people with multiple sclerosis, for instance, notice vision changes that are exacerbated by high body temperatures. A rare condition in which the pigment from the eye’s iris becomes dislodged can also cause blurred vision during exercise. A cardiovascular problem may also be to blame.