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Ultra-Violet (UV)
Radiation and Sunlight The Bottom Line Without proper ultra-violet (UV) protection, you increase your risk of skin cancer, cataracts, and macular degeneration. Background Sunlight is composed of 3 types of UV
radiation: UV-A and UV-B (which are both dangerous), and UV-C (which is
absorbed by the ozone layer). UV-B can cause sunburn and lead to
cancer. The cornea (front surface of the eye) and the lens inside the eye
absorb more than 99% of this form of radiation to protect (as much as possible)
the retina in the back of the eye. UV-A radiation penetrates deeper into
the eye and can cause damage to the retina. Damage to the Eyes Photokeratitis - Occurs after overexposure to UV radiation over a short period of time. The front surface of the cornea absorbs UV-B radiation and the cells melt together. This "sunburn of the eye" can cause foreign body sensation, light sensitivity and excessive tearing. Effects are usually temporary with no long-term effects. Cataracts - Occur after cumulative long-term exposure (over a lifetime) to UV radiation. Cataracts occur in the lens, which is located just behind the pupil. The lens helps focus light onto the retina to give you a clear image. The center of the lens absorbs UV-B radiation, which causes an opacity or cloudiness. Thus, when a cataract forms, you see a blurry image that cannot be improved with glasses. Though cataracts can be surgically removed and replaced with a prosthetic lens, why not prevent them if you can? Age-Related Macular Degeneration (AMD) - Some clinicians have projected that extended exposure to UV radiation can contribute to the aging process of the retina which can lead to AMD. Laboratory studies show that both UV and deep blue light cause retinal damage. As well, chronic exposure to short-wavelength visible light (blue light) can cause damage to the macula. Pterygium - This is an overgrowth of blood vessels and fibrous tissue that starts on the white of the eye (as a pinguecula) and grows onto the cornea, possibly causing vision loss. It is prevalent in people who work outdoors in the sun and wind. Pterygia can be surgically removed, but recurrence can occur. Skin Cancer - Most people know about this risk and apply sun block accordingly. But not many think about the risk to eyelids and the skin around the eyes that could be covered by sunglasses. Protection A chemical UV protective coating on the lens surface
of sunglasses should block 99-100% of both
UV-A and UV-B radiation. The American Optometric Association offers a Seal
of Acceptance to sunglasses that meet these standards. You should be aware
that some sunglasses may have a label that declare an amount of UV protection,
but these labels may be misleading or lack any guarantee. Do blue-blocking
sunglasses provide more protection? Scientists disagree on whether blue
light even causes any damage to the eyes. But, this isn't a big concern
during the summer months (or those locations where the sun shines most of the
time), since the highest exposure to blue light comes from snow reflection.
Prevent Blindness America - www.preventblindness.org
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