Ultraviolet (UV) Radiation and Your Eyes
Did you know that UV and other radiation from the sun also can harm your eyes? Extended exposure to the sun's UV rays has been linked to eye damage, including cataracts. macular degeneration , pterygia and photokeratitis that can cause temporary vision loss.
Dangers of Ultraviolet Radiation to Your Eyes
To protect your eyes from harmful solar radiation, sunglasses should block 100 percent of UV rays. Frames with a close-fitting style provide the best protection because they limit how much stray sunlight reaches your eyes from above and beyond the periphery of your sunglass lenses.There are three categories of invisible high-energy UV rays:
- UVC rays. These are the highest-energy UV rays and potentially could be the most harmful to your eyes and skin. Fortunately, the atmosphere's ozone layer blocks virtually all UVC rays.
- UVB rays. These rays are filtered partially by the ozone layer, but some still reach the earth's surface. In low doses, UVB radiation stimulates the production of melanin (a skin pigment), causing the skin to darken, creating a suntan. But in higher doses, UVB rays cause sunburn that increases the risk of skin cancer. UVB rays also cause skin discolorations, wrinkles and other signs of premature aging of the skin.
- UVA rays. These are closer to visible light rays and have lower energy than UVB and UVC rays. But UVA rays can pass through the cornea and reach the lens and retina inside the eye. Overexposure to UVA radiation has been linked to the development of certain types of cataracts, and research suggests UVA rays may play a role in development of macular degeneration.
To protect your eyes outdoors, wear broad-brimmed hats and sunglasses with 100 percent UV protection. Include a UV coat on your spectacles , or look into having sighted sunglasses or photomatic lenses fitted. Your optician will be able to guide you on your options. Various eye problems have been associated with overexposure to UV radiation. As an example, UVB rays are thought to help cause pingueculae and pterygia. These growths on the eye's surface can become unsightly and cause corneal problems as well as distorted vision. In high short-term doses, UVB rays also can cause photokeratitis, a painful inflammation of the cornea. "Snow blindness" is the common term for severe photokeratitis, which causes temporary vision loss usually lasting 24-48 hours. The risk for snow blindness is greatest at high altitudes, but it can occur anywhere there is snow if you don't protect your eyes with UV-blocking sunglasses. Because the cornea appears to absorb 100 percent of UVB rays, this type of UV radiation is unlikely to cause cataracts and macular degeneration, which instead are linked to UVA exposure. Anyone who spends time outdoors is at risk for eye problems from UV radiation. Risks of eye damage from UV depend on a number of factors, including:
- Geographic location. UV levels are greater in tropical areas near the earth's equator. The farther you are from the equator, the smaller your risk.
- Altitude. UV levels are greater at higher altitudes.
- Time of day. UV levels are greater when the sun is high in the sky, typically from 10 a.m. to 2 p.m.
- Setting. UV levels are greater in wide open spaces, especially when highly reflective surfaces are present, like snow and sand. In fact, UV exposure can nearly double when UV rays are reflected from the snow. There is less risk of UV exposure in urban settings, where tall buildings shade the streets.
- Medications. Certain medications, such as tetracycline, sulfa drugs, birth control pills, diuretics and tranquilizers, can increase your body's sensitivity to UV .
Surprisingly, cloud cover doesn't affect UV levels significantly. Your risk of UV exposure can be quite high even on hazy or overcast days. This is because UV is invisible radiation, not visible light, and can penetrate clouds.
Kids Need UV Protection Even More Than Adults
The risk of damage to our eyes and skin from solar UV radiation is cumulative, meaning the danger continues to grow as we spend time in the sun throughout our lifetime.
With this in mind, it is especially important for kids to protect their eyes from the sun. Children generally spend much more time outdoors than adults.
In fact, experts say as much as 80 percent of our lifetime exposure to UV rays occurs by age 18.
Therefore, make sure your kids' eyes are protected from the sun with good quality sunglasses.
Sunglasses That Protect Your Eyes From Rays
To best protect your eyes from the sun's harmful UV rays, always wear good quality sunglasses when you are outdoors.
Look for sunglasses that block 100 percent of UV rays. Your optician can help you choose the best sunglass lenses for your needs.
To protect as much of the delicate skin around your eyes as possible, try at least one pair of sunglasses with large lenses or a close-fitting wraparound style.
The amount of UV protection sunglasses provide is unrelated to the color and darkness of the lenses. A light amber-colored lens can provide the same UV protection as a dark gray lens. Your optician can verify that the lenses you choose provide 100 percent UV protection.
In addition to sunglasses, wearing a wide-brimmed hat on sunny days can reduce your eyes' exposure to UV rays by up to 50 percent.
More Tips About Sunglasses and UV Exposure
This UV Index devised by the Environmental Protection Agency and National Weather Service provides a color-coded warning system to alert people to the dangers of being outdoors on certain days.
Many misconceptions exist about the right sun protection for your eyes. Keep these tips in mind:
- Not all sunglasses block 100 percent of UV rays.
- Remember to wear sunglasses even when you're in the shade. Although shade reduces your UV exposure to some degree, your eyes still will be exposed to UV rays reflected from buildings, roadways and other surfaces.
- Some brands of contact lenses have a UV blocking agent incorporated into the lenses; Ask your optician for these;
- Even if your contact lenses block UV rays, you still need sunglasses. UV-blocking contacts shield only the part of your eye under the lens. UV rays still can damage other tissues not covered by the lens. Wearing sunglasses protects these delicate tissues and the skin around your eyes from UV damage.
- If you have dark skin and eyes, you still need to wear sunglasses. Although your dark skin may give you a lower risk of skin cancer from UV radiation, your risk of eye damage from UV rays is the same as that of someone with fair skin.