Almost everyone is aware of the damage solar energy, including ultraviolet (UV) radiation, can do to the skin. What is not as well known is the damage UV radiation does to the eye. This UV exposure is cumulative, so the exposure while on the beach as a child will add to the effects that result in damage later in life.

Solar radiation reaching the surface of the eye is focused and concentrated by the cornea, the clear outermost layer of the eye. The rays that pass through the pupil of the eye are absorbed by the lens of the eye. This UV radiation may cause cataracts in the lens of the eye. Studies show that the UV radiation that reaches the eyes from above, below, and the sides is concentrated and focused when it reaches the tissue on the opposite side of the eye. This radiation may cause changes to the tissue there. Small tissue elevations, called pingueculea and pterygia, may result.

The American Optometric Association (AOA) recommends the use of sunglasses that block 99-100% of UV-A and UV-B rays to protect the eyes from this radiation. However, many styles of sunglasses do not protect the eyes from the solar radiation entering from the sides or around sunglasses.

Additional protection is offered by some contact lenses. These contact lenses absorb UV radiation by reducing the amount of radiation that reaches the surface of eye. The contact lenses also protect the areas of the eye from the radiation that comes from above or around the sides of sunglasses.

The U.S. Food and Drug Administration (FDA) has standards for UV-blocking contact lenses based on American National Standards Institute (ANSI) Z80.20 standards. There are two different classifications of UV-blocking lenses:

  • FDA Class I blocker- recommended for high exposure environments such as mountains or beaches. The lenses in this classification must block more than
    • 90% of UVA (316-380 nm wavelengths) and
    • 99% of UVB (280 – 315 nm)
  • FDA Class II blocker – recommended for general purposes. These lenses must block more than
    • 70% of UVA and
    • 5% of UVB

For people who wear contact lenses and do not wear wrap-style sunglasses, the amount of protection from UV radiation can be increased by wearing contact lenses that block UV.

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Sunglasses Shopping Guide

On August 25th, 2010, posted in: UV Protection by

People sometimes buy sunglasses the way they buy the rest of their fashion accessories: New pair every spring with an emphasis on fashion over function. They often don’t forget about being in the sun and the effects of ultraviolet (UV) radiation.

While doctors advise the use of eye protection, the multi-billion dollar sunglass marketplace is anything but easy to navigate.

The American Optometric Association has important information on sunglass function that can make sunglass shopping easier. Keep in mind that sunglass function and fashion are not incompatible.

WHY PEOPLE NEED SUNGLASSES

People need sunglasses for:

  • UV Protection. The sun’s UV radiation can cause cataracts; benign growths on the eye’s surface; cancer of the eyelids and skin around the eyes; and photokeratitis, sometimes called snow blindness, which is a temporary but painful sunburn of the eye’s surface. Wide-brimmed hats and caps can block about 50 percent of UV radiation from the eyes but optometrists say that is not enough protection.
  • Blue-Light Protection. Long term exposure to the blue and violet portion of the solar spectrum has been implicated as a risk factor for macular degeneration especially for individuals that are “sun sensitive.”
  • Comfortable vision. The sun’s brightness and glare interferes with comfortable vision and the ability to see clearly by causing people to squint and the eyes to water.
  • Dark adaptation. Spending just two or three hours in bright sunlight can hamper the eyes’ ability to adapt quickly to nighttime or indoor light levels. This can make driving at night after spending a day in the sun more hazardous.

People should wear sunglasses outdoors whether they are working, driving, participating in sports, taking a walk, running errands or doing anything in the sun.

WHAT PEOPLE NEED IN SUNGLASSES

People need sunglass lenses that:

  • block 99 to 100 percent of both UV-A and UV-B radiation;
  • screen out 75 to 90 percent of visible light;
  • are perfectly matched in color and absorption and are free of distortion and imperfection;
  • are gray for proper color recognition.

More info:
AllAboutVision.com – Sunglasses

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  • UV Protection with Contact Lenses
  • Sunglasses Shopping Guide

Protecting Your Eyes from Solar Radiation

The sun supports all 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. UV radiation is a component of solar radiation, but it can also be given off by artificial sources like welding machines, tanning beds and lasers.

Most are aware of the harm UV radiation can do to the skin, but many may not realize that exposure to UV radiation can harm the eyes or that other components of solar radiation can also affect vision.

There are three types of UV radiation: UV-C is absorbed by the ozone layer and does not present any threat; UV-A and UV-B radiation can have adverse long- and short-term effects on the eyes and vision.

If your eyes are exposed to excessive amounts of UV radiation over a short period of time, you are likely to experience an effect called photokeratitis.

Like a “sunburn of the eye”, photokeratitis may be painful and include symptoms such as red eyes, a foreign body sensation or gritty feeling in the eyes, extreme sensitivity to light and excessive tearing. Fortunately, this is usually temporary and rarely causes permanent damage to the eyes.

Long-term exposure to UV radiation, however, can be more serious. Scientific studies and research have shown that exposure to small amounts of UV radiation over a period of many years increases the chance of developing a cataract and may cause damage to the retina, a nerve-rich lining of the eye that is used for seeing. Additionally, chronic exposure to shorter wavelength visible light (i.e. blue and violet light) may also be harmful to the retina.

The longer the eyes are exposed to solar radiation, the greater the risk of developing later in life such conditions as cataracts or macular degeneration. Since it is not clear how much exposure to solar radiation will cause damage, the AOA recommends wearing quality sunglasses that offer UV protection and wearing a hat or cap with a wide brim whenever you spend time outdoors. Also, certain contact lenses can provide additional UV protection ( See: UV Protection with Contact Lenses ).

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;
  • be perfectly matched in color and free of distortion and imperfection; and
  • have lenses that are gray for proper color recognition.

The lenses in sunglasses should be made from polycarbonate or Trivex® material if you participate in potentially eye-hazardous work or sports. These lenses provide the most impact resistance.

If you spend a lot of time outdoors in bright sunlight, wrap around frames can provide additional protection from the harmful solar radiation.

Don’t forget protection for children and teenagers. They typically spend more time in the sun than adults.

Be sure to see your doctor of optometry at least every two years for a comprehensive eye examination. It is a good way to monitor your eye health, maintain good vision and keep track of your solar radiation protection needs as well as new advances in eye protection.

UV Radiation Checklist

If you can answer “yes” to one or more of the following questions, you could be at higher risk for harm to the eyes from UV radiation:

  • Do you spend a great deal of time outdoors?
  • Do you spend time skiing, mountain climbing or at the beach?
  • Do you use a sunlamp or tanning parlor?
  • Do you live in the mountains or the United States Sunbelt?
  • Are you a welder, medical technologist or do you work in the graphic arts or in the manufacture of electronic circuit boards?
  • Do you take prescription or over-the-counter drugs that can increase your sensitivity to UV radiation (check with your optometrist, pharmacist, or physician)?
  • Have you had cataract surgery in one or both eyes?

 

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