In terms of UV protection, since ultraviolet radiation is ‘invisible light’, it’s not affected by any ‘visible tint’. That being said, the tint on the lens is important for brightness, glare, and contrast: gray tints block all light equally, while brown lenses preferentially block greens, and rose or amber (‘blue-blockers’) improve contrast by reducing scatter. Polarized lenses block reflected light from flat surfaces including snow and water, making them ideal for skiers and boaters. In short, tints are selected mainly based upon patient preference, while coatings and materials are selected for protection.
With sunglass prices ranging from less than $10 to as much as $500, this is a good question. Remember that higher prices do not always indicate better quality, and designer labels often carry designer pricing. Providing that the frame is durable and comfortable, and the lens provides 100% UV protection while minimizing distortion, an inexpensive pair of sunglasses may be more than adequate. More expensive sunglasses, however, incorporate anti-reflection coatings, photochromic lenses, and/or polarization, and be worth the added expense. Our practice selection includes Maui Jim, Kaenon, RayBan, Hugo Boss, and others, in styles and at price points to accommodate everyone.
Contrary to popular belief, the actual tint (color) of the lens is not as important as the material or coating, which are responsible for UV blocking. It is critical that all UV-A and UV-B rays are blocked: look for your lens to have CSA or ANSI approval to indicate that it provides full UV protection. Wrap-around frame styles are beneficial in preventing UV from reaching the eye around the frame, and when accompanied by a brimmed hat, can provide excellent protection and comfort.
For the same reason that you need to wear sunscreen: the sun’s ultraviolet radiation damages tissue, causing at best sunburn and dry eye, and at worst melanoma and age-related macular degeneration. Sunglasses are essentially sunscreen for your eyes. A quality UV-blocking lens doesn't have to be expensive, but is critical for anyone spending any amount of time outdoors, whether winter or summer, bright or overcast.