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Eye health begins with protection from risky UV rays
 You slather on the sunscreen to protect your skin against the well-known dangers of UV radiation, but you should also be shielding your eyes from harmful UV rays, say the eye experts. Why? UV rays can cause significant damage to eye tissues, inside and out, which can put you at risk for vision loss and cancer. The Health Journal spoke with Dr. Ralph Chou, MSc, OD, associate professor at the University of Waterloo's School of Optometry, in Waterloo, Ontario, about health hazards of UV exposure for your eyes, and how to guard against them.
The Health Journal: Why are UV rays dangerous to the eyes?
Dr. Ralph Chou: The eye is built to transmit light to the back of the eye so we can see. That includes UV light, so some UV wavelengths can penetrate quite deeply into the eye. We know that the tissue in the eye is vulnerable to UV damage, and unlike the skin, the eye does not have any protection against UV damage. The skin responds to UV damage with a tan. Skin pigment forms in the tanned skin, which protects the underlying tissue from further damage. However, the pigmentation, or the tan itself, indicates that some damage has occurred in the superficial layers of the skin. We do not have any kind of protective pigmentation formed in the eye at all. It does not matter what your skin or hair colour happens to be, your eyes are always vulnerable to UV radiation. We know that overexposure is going to result in some kind of damage.
THJ: Can your eyes get a sunburn?
RC: The most common reaction of this type is not caused from the sun, but from exposure to an electric welding arc, which produces UV light. However, it is possible for people to have a similar reaction if they are out on snow or water for a long time without protecting their eyes. We refer to it as "snow blindness," but it's basically a sunburn to the front of the eye from UV radiation and sunlight. Although fairly rare, it does occur. And it really does damage the tissues at the front of the eyes.
THJ: We know that overexposure to the sun can cause skin cancer. Can it also cause eye cancer?
RC: Yes. Overexposure can lead to the development of cancers within some of the eye tissues over the long term. The more common concern we have is that people who sunburn their eyelids can develop skin cancer there. This becomes a significant problem, and cancer of the eyelids is a fairly common form of skin cancer. It can be very disfiguring, because portions of the eyelids have to be cut out. One of the problems with having a tumour on the eyelid is that you have to remove so much of that eyelid tissue. It disrupts the function of the lid to channel tears from the tear ducts, so you have problems controlling the flow of tears over the eye. It's hard to keep the eye moist, and there could be other effects as well - not to mention the cosmetic results. The type of cancer determines whether it will be aggressive and widespread (squamous cell carcinoma) or slow-grow-ing and confined (basal cell carcinoma), which can be excised with-out too much disfigurement.
THJ: Should people be concerned about using sunbeds?
RC: People who frequent tanning salons or who have extensive sun exposure can develop pigmented skin cancers, the malignant melanomas. We also know that, occasionally, some of the pigmented tissues within the eyes may develop malignant melanomas. You can have either primary or secondary tumours. Primary tumours develop when UV exposure on the rest of the body triggers a tumour formation in the eye tissue. Secondary tumours result when a malig-nant melanoma in the skin has a cell break off, which then travels through the blood to the eye. It becomes lodged in the eye tissue and starts to grow there.
If you have one of these types of cancer resulting from overexposure to UV rays, without sunburns but with a deep tan, you could lose an eye. What is fortunate is that it is not common, but it can be devastating to the person involved.
THJ: What other effects can be caused from long-term chronic exposure to UV rays?
RC: One of them is cataracts. We know that UV radiation does accelerate aging of the tissues of the eye just as it does to skin aging. When that happens in the eyes, it creates an area of haze that even-tually clouds the lenses to the point where it starts to substantially impair vision. Cataracts occur more frequently in people who are out in the sun as part of their work or their daily lives. They are the ones that show more accelerated aging changes in the eyes.
THJ: What is the best way to protect our eyes from UV exposure?
RC: We are looking at what the Canadian Cancer Society refers to as sun avoidance. We can choose to play tennis or hit the golf course at a time of the day when the UV rays are not at their peak. Except for job-related activities, you can change your schedule so you can enjoy yourself without unnecessarily exposing yourself to the sun. If you can't avoid the sun, try to reduce your exposure by wearing protective gear, such as sunglasses, a wide-brimmed hat and sunscreen.
THJ: Do you recommend any particular types of lenses?
RC: If someone needs prescription lenses, the modern, plastic photochromic are very good. They darken in sunlight and are clear indoors, blocking 100 percent of UV radiation. They are effective outside in providing both glare reduction and UV sun protection. Plastic sun lenses that are labelled as UV-blocking and polarizing sun lenses also have good sun-blocking properties,
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