I'm not so certain that the issue is the definition of the term normal, so much as it is the value (positive or negative) or association (healthy vs. unhealthy) the term implies in a medical or social context.
One of the most common reasons for blurry vision while wearing contacts is that your eyes are dry. Some people have a medical condition that causes dry eyes, called dry eye syndrome, but others' eyes are irritated by the contacts themselves.
Francis says to tell your eye doctor if you're experiencing blurry vision, eye pain, headaches, or loss of vision. The doc will also check you for drooping eyelids (a sign that a blood vessel may have ruptured or is leaking), increased pressure in your eye, bleeding in the retina, and swelling of your optic nerve. Crossed eyes can be another sign of bleeding in the brain, possibly from an aneurysm or even a stroke.