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.
Millions of people wear contact lenses safely every day. But there is a risk of getting an eye infection from them. Keratitis is the most common infection from wearing contact lenses. It is when the corneaâthe clear, front window of the eye â becomes infected. In some cases, it can scar the cornea, affecting your vision. If the cornea is severely scarred, a cornea transplant may be needed to have clear vision again.