I picked up prescription sunglasses today. And I put sunglasses in front of my laptop computer and suddenly I found out there are about 4 burning spot on surface of each lens. When I wear it, I could not recognize it. Only I can recognize it see through the LCD monitor. Is this normal or manufacturing defect? Thanks

What you are seeing is the polarization effect of the lenses. If you rotate the lenses while you look through them, you will find varying degrees of light being filtered and unfiltered. There is nothing wrong with your lenses and is quite normal.