The sun supports life on our planet, but its life-giving rays also pose dangers. The sun’s primary danger is in the form of ultraviolet (UV) radiation.
Most people are aware of how harmful UV radiation is to the skin. However, many may not realize that UV radiation can harm the eyes.
While the eye is recessed within the anatomy of the head and shielded well by the brow ridge, the eyebrows and the eyelashes, these anatomical adaptations are of limited use in UV protection. Even the mechanisms like the constriction of the pupil and the closure of the eyelids, which minimize the penetration of the sun’s rays into the eye, are activated by bright visible light, but not by UV radiation. Therefore, the effectiveness of these natural defence systems in protecting against UV damage is limited.
Cataracts are the most common cause of vision loss in people over age 40 and is the principal cause of blindness in the world. With age, some of the eye protein may clump together and start to cloud an area of the lens, causing Cataract. Even though cataracts appear to different degrees in most individuals as they age, they appear to be enhanced by exposure to UV radiations. Cataracts can be surgically removed and an artificial lens or other means of optical correction can restore vision.
Every year some 16 million people in the world suffer from blindness due to a loss of transparency in the lens. WHO estimates suggest that up to 20 per cent of cataracts may be caused by overexposure to UV radiation and are therefore avoidable.
The longer the eyes are exposed to solar radiation, the greater the risk of developing cataracts or macular degeneration later in life. It is not clear how much exposure to solar radiation will cause damage. Therefore, whenever you spend time outdoors, wear quality sunglasses that offer UV protection. To provide adequate protection for your eyes, sunglasses should:
- block out 99 to 100 percent of both UV-A and UV-B radiation
- screen out 75 to 90 percent of visible light
- have lenses that are perfectly matched in color and free of distortion and imperfection and
- have lenses that are gray for proper color recognition.