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.
The rumor: You can damage your eyes by looking at a computer screen for too long After staring at a monitor for hours on end, have your eyes ever felt dry, itchy or irritated? Has your vision become blurry, or have you even seen double?