Best sunglasses to protect your eyes from ultraviolet (UV)
You probably know that too much exposure to the sun's ultraviolet (UV) rays can cause sunburn and skin cancer. Did you know UV also can harm your eyes?
Extended exposure to the sun's UV rays has been linked to eye problems, including cataracts,, pingueculae, pterygia and photokeratitis.
Protecting your eyes from UV
To protect your eyes from harmful solar radiation, you should wear sunglasses that block 100 percent UV whenever you are outdoors in daylight hours. Your eyes need protection even on cloudy days because the sun's damaging UV rays penetrate through cloud cover.
What is UV?
While many people refer to ultraviolet radiation as "UV light," this term technically is incorrect because you cannot see UV rays. Ultraviolet radiation is invisible.
There are three categories of UV radiation:
These are the highest energy UV rays and would be the most harmful to your eyes and skin, but fortunately, the atmosphere's ozone layer blocks virtually all UVC rays.
This also means that depletion of the ozone layer could potentially allow high-energy UVC rays to reach the Earth's surface and cause serious UV-related health problems.
UVC rays have wavelengths that range from 100 to 280 nanometers (nm).
UVB rays have slightly longer wavelengths (280-315 nm) and lower energy than UVC rays. These rays are filtered partially by the ozone layer, but some still reach the Earth's surface.
In higher doses, UVB rays cause sunburn that increases the risk of skin cancer. UVB rays also cause skin discolourations, wrinkles and other signs of premature ageing of the skin.
As the cornea appears to absorb 100 percent of UVB rays, this type of UV radiation is unlikely to cause cataracts, which instead is linked to UVA exposure (see below).
UVA rays are closer to visible light rays and have lower energy than UVB and UVC rays, but UVA rays can pass through the cornea and reach the lens and retina inside the eye.
Overexposure to UVA radiation has been linked to the development of certain types of cataracts, and research suggests UVA rays may play a role in development of macular degeneration.
UV risk factors
Anyone who spends time outdoors is at risk for eye problems from UV radiation. The actual dose of UV radiation you get outdoors depends on a number of factors, including:
UV exposure is greater in tropical areas near the earth's equator. The farther you are from the equator, the smaller your risk.
UV exposure is greater at higher altitudes.
Time of day
UV exposure is greater when the sun is high in the sky, typically from 10 a.m. to 2 p.m. Recent research has shown that for people who wear glasses, the period when the sun is lower in the sky, say 2pm to 4pm, allows UV rays to reflect off the back of their lenses and onto their eyes, even if they are walking away from the sun.
UV exposure generally is greater in wide open spaces, especially when highly reflective surfaces are present, like snow and sand. In fact, UV exposure can nearly double when UV rays are reflected from the snow. UV exposure is less likely in urban settings, where tall buildings shade the streets.
Certain medications, such as tetracycline, sulphur drugs, birth control pills, diuretics and certain anti-anxiety medications, can increase your body's sensitivity to UV radiation.
Children need UV protection, too
The risk of damage to our eyes and skin from solar UV radiation is cumulative — meaning the danger continues to grow the more time you spend in sunlight throughout your lifetime.
With this in mind, it's especially important for kids to protect their eyes from the sun. Children generally spend much more time outdoors than adults.
In fact, some experts say that because children tend to spend significantly more time outdoors than most adults, up to half of a person's lifetime exposure to UV radiation can occur by age 18.
Also, children are more susceptible to eye damage from UV rays because the lens inside a child's eye is clearer than an adult lens, enabling more UV to penetrate deep into the eye.
Make sure your children's eyes are protected from the sun with good quality sunglasses or photochromic lenses when they go outdoors. Sunglasses are now part of Cancer Council Australia and Cancer Society New Zealand's recommendations - slip, slop, slap, seek and slide - slip on a shirt, slop on sunscreen, slap on a hat, seek shade and slide on sunnies, all helping to reduce UV exposure.
Sunglasses that protect your eyes from UV
To best protect your eyes from the sun's harmful UV rays, always wear good quality sunglasses when you are outdoors.
Look for sunglasses that block 100 percent of all UV rays. Your optometrist can help you choose the best sunglass lenses for your needs.
To protect as much of the delicate skin around your eyes as possible, try at least one pair of sunglasses with large lenses or a close-fitting wrap-around style.
The amount of UV protection sunglasses provide is unrelated to the colour and darkness of the lenses.
For example, a light amber-coloured lens can provide the same UV protection as a dark grey lens. Your optometrist can verify that the lenses you choose provide 100 percent UV protection.
More tips about sunglasses and UV exposure
Many misconceptions exist about sun protection for your eyes. Keep these tips in mind:
Not all sunglasses block 100 percent of UV rays
If you're unsure about the level of UV protection your sunglasses provide, ask your optometrist. Some eye care professionals have instruments that can measure the amount of UV radiation your lenses block.
Remember to wear sunglasses even when you're in the shade
Although shade reduces your UV and HEV exposure to some degree, your eyes still will be exposed to UV rays reflected from buildings, roadways and other surfaces.
Sunglasses are needed year-round
Sunglasses also are important in winter, when you're skiing fresh snow can reflect 80 percent of UV rays, nearly doubling your overall exposure to solar UV radiation. If you ski or snowboard, choosing the right lenses is essential for adequate UV protection on the slopes.
Even if your contact lenses block UV rays, you still need sunglasses
UV-blocking contacts shield only the part of your eye under the lens. UV rays still can damage your eyelids and other tissues not covered by the lens. Wearing sunglasses protects these delicate tissues and the skin around your eyes from UV damage.
If you have dark skin and eyes, you still need to wear sunglasses
Although dark skin colour may give you a lower risk of skin cancer from UV radiation, your risk of eye damage from UV rays is the same as that of someone with fair skin.
Everyone enjoys a sunny day, but be safe and make sure you have the right sunglasses to shield your eyes from the sun's harmful UV rays.