What is ultraviolet radiation?

Ultraviolet radiation is made up of high energy rays from the sun that lie just beyond the end of the visible light spectrum. Most of the UV radiation is absorbed by the anterior structures of the eye, but some may reach the light-sensitive retina.

Based on how it travels, UV radiation is divided into three bands: UVA, UVB and UVC. 		 
 
UVA radiation reaches the earth in very large amounts. It enters the eye and is a contributor to aging and cancer of the skin around your eyes. UVA rays remain constant year round.
 
UVB radiation, called "sunburn rays," is high energy radiation. UVB rays cause sunburn, which is skin damage, and snow blindness, which is sunburn of the retina. UVB radiation can cause keratitis (cornea irritation) and has been linked to the development of cataracts. UVB also may cause cataracts, macular degeneration, and other harmful eye diseases that cause permanent, irreversible damage. UVB rays are more intense during the summer months.
 
UVC radiation is absorbed by the ozone layer and never reaches the earth's surface.
 
Who is at risk for UV overexposure?
EVERYONE is at risk for UV damage. No one is immune to sun-related eye disorders and ocular damage caused by exposure to ultraviolet radiation.

You are at an even greater risk for damage if you:
  • have light-colored eyes
  • are sensitive to light
  • live in a high altitude
  • live close to the equator
  • spend a great deal of time outdoors
  • wear contact lenses
  • commute during high-glare conditions
  • have had refractive or cataract surgery
  • are a child or senior citizen
  • taking certain medications, particularly birth control, antibiotics, sulfa drugs, diuretics and tranquilizers
If you are in an elevated risk group, you should ALWAYS wear sunglasses designed to block UVA and UVB radiation. In fact, everyone should wear sunglasses regularly to prevent eye damage.
 
What kind of damage can UV radiation cause?
Exposure to ultraviolet radiation can cause irreparable damage to you eyes and your vision. Everyday exposure to UV rays can lead to or cause:
  • Macular degeneration, the leading cause of vision loss in people over 50.
  • Cataracts, a cloudiness in the focusing lens inside the eye.
  • Melanoma, the deadliest form of skin cancer, including in the eyelids and around the eyes.
  • Pterygium, tissue growth that can block vision and cannot be removed without surgery.
  • Photokeratitis, or sunburn of the outer surface of the eye, which is excruciatingly painful and can damage the cornea.
  • Blurred vision.
  • Changes in color vision.
  • Degradation of night vision.
  • Skin aging, particularly fine lines and wrinkles around the eyes.
 
How does UV radiation affect children?
Children's developing eyes let in more ultraviolet rays than adults'. And children tend to spend more time outdoors than their parents. Protecting your skin and eyes from sun damage during the first 18 years of life may reduce the risk of cancer and other eye diseases by more than 50%.
 
Is it safer in the shade or when it's cloudy? In the winter?
As long as it is daytime, you are always at risk for exposure to UV radiation. Clouds can cut down the amount of UV radiation, but the risk is still high, even for sunburn and damage. In some instances, UV radiation can even penetrate clouds, mist and fog.

It is better in the shade, but shade does not eliminate risk. A considerable amount of UV radiation comes not directly from the sun, but scattered in the atmosphere.

UV risk is highest in summer and lowest in winter, but winter conditions do not eliminate risk. In snowy situations, risk for damage is even greater because of the reflectivity of snow. Fresh snow reflects up to 80% of the sun's rays, which can cause both sunburn and snow blindness, which is just another way of saying retinal sunburn. Winter sports enthusiasts are at high risk for damage and should always protect their eyes and exposed skin from sun damage.
 
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04.25.07