Would it make you feel better if I told you I once spilled superglue on an expensive calculator and stuck the keys in the 'up' position? The calculator mfgr used acetone (regular nailpolish remover) to take off the glue. BUT regular nailpolish remover melts ordinary plastic - that's why they make non-acetone remover for false nails. So, it depends what your brother's glasses are made out of. If they're plastic lenses or frames, I'd try a TINY area somewhere on them with a Qtip and a little nailpolish remover first. If it goes soft and cloudy, try to find an optometrist to help you.