MadSci Network: Medicine

Re: Are all kinds of man-made Ultraviolet light harmful to human vision?

Date: Sat Sep 11 09:37:01 1999
Posted By: Jeffrey Utz, M.D., Neuroscience, pediatrics, Allegheny University
Area of science: Medicine
ID: 936039502.Me

It does not matter what the source of UV light is (whether it is from the 
sun or manmade). All forms of UV light can be harmful to the eyes and 
skin. (You asked specifically about eyes, however, a lot of damage is done 
to the skin, so I included damage to the skin as well in my answer.)

As you mention, UV light is divided by wavelength into three groups, UV-A, 
UV-B and UV-C. 

UV-C light is the most dangerous, but it is filtered out by the 
atmosphere. Because of this, it will not be discussed further.

UV-B light does not penetrate into deeply into the skin, but can cause 
skin cancer. This light is partly filtered out by the atmosphere.

UV-A light penetrates more deeply than UV-B and causes damage to the skin 
and the connective tissues supporting the skin. This light also causes sun 
tans and sun burns.

All of these forms of UV light can cause skin cancer, wrinkling and aging 
of the skin. In addition, UV light cause cataracts, which is a clouding of 
the lenses of the eyes which requires artifical lens implanted during 
surgery. THis is such a big problem that cataract surgery is the mostc 
common surgery of the elderly in the US. It can also cause macular 
degeneration, which is the most common form of blindness in those over 50 
years of age.

IN addition to sun exposure during the summer, sun exposure during the 
winter can be damaging as well. For example, the UV light reflected by sun 
can cause a really bad sunburn. This is true for the light reflected by 
the beach and water in the summer as well.

You did not mention a specific way UV light is made by man. There are 
special UV lights that are used in medicine, for example, to see fungal 
infections on the skin or scratches on the surface of the eyes. However, 
these lights are not of the right type to really damage the eyes during 
the short duration that the eyes are exposed to the light. However, other 
sources of UV light can be damaging to the eyes. One is the UV light that 
is made when someone is arc welding. This light can cause a burn to the 
surface of the eye, cuasing damage similar to a sunburn of the eye.

Other sources of information including from the Centers for Disease 
Control and Prevention (for skin cancer, mostly; and from the American 
Acadamy of Opthamology (eye stuff;

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