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.
But eye diseases arenât the only thing that can cause your vision to be blurry. This issue can affect one eye or both eyes, and can occur often or rarely. Either way, if you notice your vision becomes blurry, contact your eye doctor sooner rather than later.