While makeup has now added function to its fashion, sunglasses have done the reverse. Most lenses have been protecting the eyes from UV rays for years but now they look good in the process.

UVA rays can permanently damage an eye's retina and UVB rays are absorbed by the cornea, according to Chris Cummings of Smith Sport Optics.

UV protection is colorless, according to Chris Cummings of Smith Sport Optics, so the color of the lens doesn't matter from a practical standpoint. It only matters as a personal preference -- both in how you see the world and how the world sees you.

Eye color mixed with lens color can change your "vision," says Cummings.

Smith Sport, which targets its sunglasses toward cyclists, hikers, skiers and other outdoor enthusiasts, offer a polarized collection, which reduces horizontal glare.

Polarized lenses are actually two glass lenses with a film in between, Cummings explains. The process cuts down on horizontal glare, acting like a Venetian blind.

Accessories designer Kate Spade says UV standards are the most important factor in creating sunglasses, but the fashion aspect cannot be ignored.

"Sunglasses are particularly personal because they are on your face. They are the first thing people will notice," says Spade, who recently launched her first line of eyewear.

Since her background is fashion, she enjoyed experimenting with different lens colors, and details on the bridge and arm. And the perfect marriage of fashion and function is big lenses because they keep the sun out and make a statement.

There is something about big sunglasses that give people, and women in particular, a presence, observes Spade. She carries two pairs in her purse -- one with round frames, the other square.

3- Shades