Does being hungover cause blurry vision?

Hungover. The hangover itself does not cause blurring. However, since alcohol is a diuretic, the body becomes dehydrated, and the eyes dry out, leading to blurred vision. If your eyes feel dry, you can try using some artificial tears, such as refresh or systane.
Yes. Being hungover can lead to dehydration or headache which can make vision blurry. After adequate rehydration, food, and possibly some mild analgesic such as aspirin, acetominophen or ibuprofen, blurriness should improve. If it persists it may indicate a more serious problem which needs medical evaluation.