Eye Disorders
Strong UV radiation from the Sun can cause inflammation of the cornea, the outer coating of the eyeball, leading to photokeratosis or "snow blindness". Symptoms of this kind of infection include the reddening of the eyes, a sensitivity to light, enhanced excretion of tears, the feeling of having some dirt in one's eye, and pain. The trauma appears 3-12 hours after exposure. Thanks to the quick regeneration of the eye cells, symptoms will normally disappear within a few days. A long-term exposure to UV radiation however, may cause permanent damage to the cornea.
UV radiation also enhances the dimming of the eye's lens, which means that potential cataracts begin to evolve at earlier ages. A cataract is a partial or complete opacity of the lens of the eye and the largest cause of blindness in the world. Part of the UV radiation reaches the back of the eye, causing cells in the retina to slowly begin to deteriorate. Damage will in time particularly occur to near vision. If not operated upon blindness can occur. Radiation is partly absorbed in the lens of an adult eye, but will go right through the lens of a child, reaching the back of the eye. For this reason, children's eyes in particular should be protected against strong sunlight.
Other common eye diseases associated with increased UV radiation are eye cancer, conjunctivitis and pterygium. Conjunctivitis is an inflammation of the membrane covering the anterior portion of the eyeball. Pterygium is a thickening of the membrane that covers the eyeball.
A loss of ozone in the stratosphere will increase the amount of UV radiation reaching the Earth's surface. If stratospheric ozone decreases by 10% during the spring and summer, the UV radiation dose increases by about 12%. Unlike the skin, which can adapt to UV radiation by becoming browner and thicker, the eye does not have any such defence mechanisms. On the contrary, research shows that eyes become more sensitive with increased exposure to UV radiation. Increased exposure to UV radiation from ozone depletion is expected to increase the number of people experiencing cataracts and other eye disorders. A 1% decrease in stratospheric ozone may result in 100,000 to 150,000 additional cases of blindness due to eye cataracts worldwide.
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