I was having a discussion about my front windshield sun shade at work and my co-worked shared an interesting thought. He used to use a sun shade but stopped because he was wondering about damage to the windshield from the heat build up. His theory is the heat would get trapped between the shade and glass and could weaken the glass. And then if the heat was esacping out of the top it could be really hot towards the top of the glass. Is there any truth to this, it sounds right but i am not sure if its factually correct. It gets pretty hot around here in the summer, 90+ a lot of the days. I wonder if the heat buildup could damage the eyesight system.