Get UV protected
UVA and UVB are the same invisible rays of light that we protect our skin from to prevent getting sunburnt. When sunlight enters the eye it creates heat or chemical reactions in the eye tissue. Much of this light is absorbed by the structures of the eye without any damage, however, these reactions can cause problems if the eye’s natural ability to cope with this is overwhelmed – either by intense exposure to strong sunlight or repeated exposure to UV over a period of time. Children are at the greatest risk from UV damage. Youngsters have bigger pupils and clearer lenses which allow up to 70 per cent more UV light to reach the retina than in an adult's eye. Kids also tend to spend more time outside without eye protection than many adults do. In fact, by the age of 18, more than half a lifetime's worth of ultraviolet light will have been absorbed by a child's eye. Our eyes are naturally ten times more sensitive to UV light than our skin. Certain medications can also increase our eyes' sensitivity to light.
Short-term effects of unprotected exposure to UV
Over exposure to UV light, such as a day at the beach or on the ski slopes – without proper eye protection, can lead to a sunburn-like condition called photokeratitis. This is an inflammation of the outer layer of the cornea and typically occurs after 6 - 12 hours exposure. Symptoms can be painful and include red, swollen and Symptoms can be painful and include red, swollen and watery eyes. In severe cases it can also lead to temporary loss of vision. These symptoms should clear up relatively quickly, say within 24 - 48 hours, and cause no permanent damage. (If they don’t, always seek advice from your optometrist.) This is the good news. However, the bad news is that cumulative exposure to UV, even on cloudy days, can greatly increase your risk of developing more serious, sight threatening conditions.
Long-term effects of unprotected exposure to UV
Studies have shown that repeated exposure to UV radiation can damage the central part of the retina and contribute to the development of age-related macular degeneration (AMD). AMD affects over 600,000 people in the UK and is the leading cause of sight loss in the UK. Across the country 300 AMD sufferers are registered blind every single week. Long-term exposure to UV can also lead to cataracts – a clouding of the lens. Cataracts affect approximately one in three Brits aged 65 and over (three million people). Every year over 300,000 cataract operations are performed on the NHS. When the cataract is removed, a small plastic lens is implanted into the eye known as an intraocular lens implant. Modern IOLs are now designed to block out the harmful effects of blue UV light. Other potential eye health problems related to long periods of UV exposure include Pterygium – a growth on the white of the eye which encroaches onto the cornea and can obscure or partially block your vision. In severe cases surgery is required to remove the growth. Repeated over exposure can also increase your risk of cancer of the eyelid and the skin surrounding the eye.
Protecting your eyes from the sun
The best way to protect your eyes against damage from UV light is to stop the rays entering the eyes with a UV protective lens. Nowadays many prescription lenses have a built-in UV filter, so, if you wear glasses or contact lenses it is worth asking your optometrist if your lenses provide protection from the sun. Sunglasses are also an excellent way of protecting your eyes from UV light. Always look out for a CE Mark or the British Standard BSEN 1836:2005 when buying sunglasses to ensure they provide adequate UV protection. Good sunglasses don't need to be expensive. It's the degree to which the lens filters UVA and UVB light that counts - not the price tag! Other safety precautions recommended by the Eyecare Trust include: wearing a wide brimmed hat and staying out of the sun between 12 noon and 3pm – when the sun’s rays are strongest.
Choosing the right lenses
Sunglasses are marked with a filter category from one to four where one is the lightest and four is the darkest. Category three is the most common tint. It is an excellent all-rounder providing comfort for sunny days, water sports and beach activities .Category four is heavily tinted for exceptionally light conditions. Many skiers find these provide comfort from the clear bright sun at high altitudes. However, the darkness of the tint on category four lenses means they are unsuitable for driving. Glasses with slim arms are particularly suitable for drivers as they allow greater all-round vision than those with heavy frames. Drivers should never wear sunglasses when driving at night or in poor light. Polarised lenses can help reduce glare from reflective surfaces such as snow or water by filtering out horizontal UV light waves. Another way to protect your eyes from UV rays is to wear a pair of photochromic lenses. These automatically darken when exposed to UV light making them an excellent choice for everyday wear.
Remember UV damage can accumulate even on cloudy days so be smart and get UV protected.
copyright: Eyecare Trust 2008