It is because you are not blinking as much when you read and when you are on a computer. Every time you blink, your eye releases oils and makes your tear form uniform so it is nice and together so you’re looking through a clean windshield. As you are driving your windshield gets dirtier, dirtier, and dirtier. If you forget to turn the wipers on, now and again, to clean it off then it is going to get very foggy. That is the analogy that I like to give my patients. Every time you blink, it's like using your wiper fluid to clean the windshield.
If you don't blink while driving you are going to get bugs and everything else on it that's going to make it foggy. Just keep blinking. Then, some people have such dry eyes that they actually have dry patches on their eyes that can interfere with their vision, but that would be more of a constant thing instead of just an intermittent blurry vision.
Dr. Jenna Zigler and Dr. Travis Zigler