Why does my vision get blurry when I run?

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Kelly asks: Why does my vision get blurry during the later part of runs?

Exercise impacts blood pressure. There may be some temporary and transient changes in your blood pressure late in your runs that could affect blood flow to the part of your brain that governs your vision clarity.

There could also be some temporary changes in the pressure inside your eye, which could cause transient blurriness. Assuming this is a regular occurrence with your runs and does not cause a permanent change, the vision blurring may have no significance.

There is a difference between blurry vision and double vision. Double vision usually means the eyes are not tracking together, and the eyes not tracking together could be due to blood flow changes in the brain or fatigue in a muscle that controls eye tracking. I would expect the eye muscle fatigue to occur with reading or computer work and not during running.

It's probably worth having your eyes examined by an optometrist or ophthalmologist. A single episode of blurring during exercise could be a signal of something worse going on like a retinal detachment, although this condition is often accompanied by floaters, flashing lights or a curtain-like change across the visual field. Although this seems like it should be a problem for older eyes, the condition is distributed in fairly equal numbers across all age groups after age 14. This condition would not go away on its own.