The basic concept that the ray ban white sunglasses work on is that no matter how wide open your pupils are only the central portion is receiving light. The pieces of plastic or metal inbetween the holes makes sure to keep light from reaching the outer edges of your pupil which in turn increases your focus and vision.
An easy way to demonstrate the affect of the ray ban sale is to close one eye while making a fist and holding it up to your open eye. Now slowly open your fist so just enough light shines though for you to see. If you do this correctly your vision will be remarkably better than when a full amount of light is hitting your pupil.