Sunglasses, often worn as a fashion statement or to shield eyes from the sun’s glare, have a function more valuable – protecting your eyes from damage and disease caused by overexposure to Ultraviolet (UV) rays. Ultraviolet (UV) rays are an invisible form of radiation from sunlight.

UV Exposure – You are at Risk

Any factor that increases your exposure to sunlight, increases your risk of eye damage. These factors include:

Damage to Your Eyes

Acute eye damage may be caused from single outings on very bright days. Excessive exposure to ultraviolet light reflected off sand, snow, water or pavement can damage the eye’s surface. Similar to a sunburn, eye surface damage usually disappears within a couple of days, but may lead to further complications.

Long-term exposure to UV radiation (“sunburn rays”) may contribute to the development of various eye disorders, such as macular degeneration, the leading cause of vision loss among older Americans, and cataracts, a major cause of visual impairment and blindness around the world.

What to Look For in Sunglasses

There are thousands of sunglasses available today. Below are the important features to look for to ensure your eyes are protected.

UV Coating

Plastic and glass lenses absorb some UV light; however, the UV protection in the plastic and glass lenses can be improved by adding a special coating to the lenses. Polycarbonate lenses offer 99 percent UV protection. Some labels read “UV protection up to 400nm” – this means 100 percent UV absorption. Be careful of purchasing sunglasses that state they “block UV” without saying how much, they need to block 99 to 100 percent of UV rays.

Mirror Coating

Mirror finishes are just thin layers of various metallic coatings on ordinary lenses. Although mirror coating reduces the amount of visible light reaching your eyes, do not assume they will protect your eyes from UV radiation. Check the label to ensure the sunglasses block 99 to 100 percent of UV rays.

Gradient Tint

Gradient lenses are permanently shaded from top to bottom or from top and bottom toward the middle. There are single gradient lenses (dark on top and lighter on the bottom) and double gradient lenses (dark on top and bottom and lighter in the middle). The single gradient lenses are useful for driving because they reduce glare while allowing you to see clearly, but are not good for sports. Double gradient lenses are the opposite – they are better for sports where light reflects up off the water or snow, but not for driving, because they make the dashboard appear dim. Tinting has little to no effect on UV protection.

Color and Darkness

The color and degree of darkness do not tell you anything about the lenses ability to block UV rays. UV coating itself is colorless. Color choice is a personal decision based on your needs and wants. Each color has different qualities to consider:

A medium tinted lens is good for day-to-day wear, but if you use the glasses for very bright conditions, select darker tinted lenses. But, don’t be fooled into thinking darker lenses offer more protection. The degree of darkness does not represent the lenses’ ability to block UV light, so be sure to check the label.

Polarized

Polarized lenses are the best way to reduce reflected glare, such as sunlight that bounces off of smooth surfaces like snow or water. These lenses are useful for skiing, fishing and driving. Polarization does not have any relation to UV light absorption, but many lenses are now combined with a UV coating. Be sure to check the label before making your purchase.

Blue Blocking

Whether blue light is harmful to the eye is still being debated; however, there is some scientific evidence the retina may be more sensitive to blue visible light. Lenses that block all blue light are tinted amber. This tint allegedly makes distant objects appear more distinct, especially in snow or haze. These lenses are popular with skiers, hunters, boaters and pilots.

Wraparound

Wraparound sunglasses are designed to keep light from shining around the frames and into your eyes, protecting your eyes from all angles.

Photochromic

Depending on the amount of UV rays exposed to, photochromic lens will change from light to dark. Although some photochromic lenses may be good UV-absorbent sunglasses, it takes time for them to adjust to different light conditions. The majority of the darkening takes place in about thirty-seconds; however, the lightening takes about five minutes.

Where Can I Get More Information?

Your Eye M.D. can provide information on sunglasses and UV protection, as well as eye health and safety. If you would like more information on sunglasses and UV safety, please visit the American Academy of Ophthalmology’s public information Web site at www.medem.com/eyemd.

Approved by: The Eye Health and Public Information Task Force. November 2003. American Academy of Ophthalmology ®