Dynamic Transparency Sunglasses

Imagine glasses that use some technology to make portions of the glasses darker, on the fly. You would be able to darken out most of the field of view, while allowing what you are actually looking at to be un-darkened. A camera follows your pupils, which lets your glasses know where what direction your eyeballs are looking. The sunglasses then darken all portions of the sunglasses except for where your eyes are focused.

Extra feature: it would have a camera facing out, to block extra heavy light. Say you are trying to look into the sun. It will detect the direction of the sun, and, calculating the position with reference to your eyeballs, will make a portion of the eyeglasses extra dark. allowing everything to be brighter because your pupils don't have to contract as much.

This idea would look exactly like a cartoon. A spot follows your eye direction, it would look like large eyeballs on sunglasses. This way, you can't stare at the girls without them knowing.