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.
Fortunately, most of the reasons for blurry vision donât threaten your eyesight. But there are times when you should visit an emergency room or at least call your doctor as soon as possible: If your vision changes suddenly and doesn't get better after you blink your eyes; If you have pain in your eye; If you have no vision in a specific area