Ultraviolet light (UV) Radiation

What Is UV Radiation?

Most people are aware of the danger of sun exposure to the skin, but many don't realize that exposure to the sun is also dangerous to our eyes. The earth's ozone layer helps block out harmful UV rays, but, unfortunately, the ozone layer is thinning. UV-related eye disorders are expected to increase within the next decade.

Sunlight that causes damage to the skin and eyes is called ultraviolet or UV radiation. Ultraviolet light is most intense when it is reflected off bright surfaces, such as concrete, snow, sand or water. Damage to the eyes caused by sunlight is cumulative with either immediate or long-term consequences.

Appropriate sunscreen and sunglasses should be used year round, but be especially careful in the summer, at the beach, and on the ski slopes. Be sure and wear appropriate goggles when using tanning beds as well. UV-emitting lamps used in tanning beds are extremely intense and can cause severe damage to the skin and eyes, even blindness. Both the American Academy of Ophthalmology (AAO) and the American Academy of Dermatology (AAD) discourage the use of tanning beds because of the potential UV dangers. If you do choose to visit a tanning bed, insist that the salon provides you with appropriate eye goggles to wear.

What is the difference between UV rays?

Three types of UV radiation exist, including UVA, UVB and UVC. However, only UVA and UVB rays reach the earth's surface and cause damage to our skin and eyes. UVC is absorbed by the atmosphere and never reaches the ground. The following describes the differences between UVA and UVB rays.

UVA rays:

Pass through glass
Are weaker and longer-wave lengths than UVB rays
Are a suspect in the development of cataracts, and might contribute to macular degeneration and aging of the retina
Burn deeper into the skin than UVB rays, and may lead to skin cancer
Cause wrinkling of the skin, premature aging and eye damage
UVB rays:

Damage the cornea (surface of the eye)
Affect the health of animals, and might retard the growth of plants
Are stronger and shorter than UVA rays
Are most intense at high altitudes and low latitudes
Can't pass through glass
Cause sunburns and skin cancer
What factors affect the intensity of UV radiation?

Environment. You receive higher UV exposure on snow, sand, water or concrete because these surfaces reflect UV rays.
Altitude. You also get more UV radiation at high altitudes, such as the mountains, and low latitudes, such as areas close to the Equator or the Caribbean. UV rays become weaker at the earth's poles.

Length of time outdoors. The more time you spend in the sun, the more ultraviolet light you receive.
Attire. Summer clothes expose the skin to more UV rays. Not wearing appropriate sunglasses expose the eyes to more harmful rays.

Time of day. UV radiation is highest between 10 a.m. and 2 p.m. In other words, if your shadow is shorter than you, UV radiation is at high intensity. If your shadow is longer, UV radiation is at lower intensity.

Season. UV radiation is the least intense in the winter, highest in the spring and summer (May to August), and lower in the fall.
Weather. Do not be fooled by a cloudy day. Be careful under haze and thin clouds. It may not be very hot outdoors, but the sun's rays can still burn.
Who is at risk for eye damage caused by ultraviolet light?

Everyone, even children, is at risk for vision loss caused by UV radiation. Any element that increases your exposure to sunlight, including certain prescription drugs that increase sensitivity to UV light, can increase your risk of eye disorders. People who work outdoors or engage in leisure activities outdoors, especially in the snow or near water, are at the highest risk. People who are fair-skinned and have light eye color also are more at risk.

Can UV Radiation Damage Our Eyes?

Did you know that the same rays that age and damage your skin can also hurt your eyes?

The following are eye disorders commonly associated with the sun and UV radiation:

Burns – Overexposure to ultraviolet light, such as a day at the beach without proper eye protection, can cause a temporary, but painful burn to the surface of the eye (cornea), similar to a sunburn on the skin. Artificial light from sources like welding arcs or tanning beds, and reflected sunlight (from snow, for example) are particularly dangerous. Staring directly at the sun can permanently scar the retina, the area at the back of the eye responsible for vision.

Pterygium – An abnormal, but usually noncancerous, growth on the corner of the eye near the nose. A pterygium can grow over the cornea, partially blocking vision, and sometimes requires surgery to be removed.

Cancer – Repeated overexposure to UV rays can cause cancer of the eyelids and surrounding skin.

Cataracts – Exposure to UV radiation over several years may lead to cataracts, a clouding of the lens.

Macular degeneration – Some studies suggest that repeated exposure to UV radiation can contribute to development of this eye disease. Macular degeneration is an eye disorder, which causes damage to the central part of the retina, called the macula. It is the major cause of blindness among Americans over age 55.

UV Protection - What you may not know is those same UV rays.

To learn more about UV radiation or the ozone layer, contact the following resources:

National Institutes of Health (http://www.nih.gov)

National Association of Physicians for the Environment (http://www.napenet.org)

The Institute for Energy and Environmental Research (http://www.ieer.org)

American Academy of Dermatology (http://www.aad.org)

Eye Cancer Network (http://www.eyecancer.com)

Climate Predication Center (http://www.cpc.ncep.noaa.gov)