Repeated UV exposure has been linked to eye diseases such as cataracts and macular degeneration, as well as damage to the surface of the eye. Polaroid sunglasses protect you from the glare of the sun. If you wear sunglasses and you squint with your sunglasses on, you are glare sensitive and a Polaroid or mirrored lens would be more appropriate for you. Tints are personal preference and do not affect the sunglasses' ability to block out UV rays. Brown tints tend to change the color of things, while with green and gray tints this is less noticeable.
Smaller frames are stylish now.
Because light can come around the frames, extra protection such as a hat is helpful in preventing UV exposure, if you are exposed to the sun on a frequent basis. Wraparound sunglasses that provide side shields are the best at blocking out harmful rays.