Alamo Optometry Blog

June 1, 2008

U.V. Light

Filed under: U.V. Light — Tags: — admin @ 10:58 pm

(As appeared in Alamo Today June 2008 edition, pg.26)

Now that we are entering the summer months, I often get asked about UV (ultraviolet) protection in glasses. There seems to be some confusion about what UV light is and how we can protect ourselves.

First of all, ultraviolet light is invisible and is divided into the categories of UV-A, UV-B, and UV-C. Generally speaking, UV-A and UV-B are most harmful to the eyes. Repeated and prolonged exposure to UV light can cause many eye conditions. The important thing to remember is that exposure to ultraviolet light is cumulative; meaning a person starts absorbing UV as a child and each day we live we add more. A person will receive about two-thirds of their entire lifetime UV radiation by the time they are 18 years old.

Depending on the duration of UV exposure, different eye conditions can occur. The most common result of a sudden amount of UV-B radiation is photokeratitis, or “sunburn on the eyes”. The most common cause is excessive glare off the snow during skiing or the water during water sports. These can be very painful, but after treatment, usually resolve within a few days.
Long-term exposure has been linked with an early onset of cataracts, pinguecula formation, and ocular melanomas. As we age, we will all develop cataracts; however, continued exposure to sunlight can speed up the process. It has been shown that people that live close to or on the equator get cataracts about 10 years sooner than people who live closer to the poles. This is due to the fact that on the equator, one receives the same amount of UV light each day. We here in California still receive UV everyday, but we receive much more in the summer months and less in the wintertime. A pinguecula is the yellowish-looking bump on the “white part” of the eye, and is a direct result of long-term UV light exposure. Most people, including myself, have them and they are completely benign. However, over time they can become red and irritated, which just makes them grow faster.

Now that we know what ultraviolet light is and what harm it can do to the eyes, what kind of defense is there? The easy one is to never leave your house, but that is not very practical. Our next best choice is UV-blocking lenses in our glasses or sunglasses. The UV coating on your lenses is a clear coating and it does not change the appearance, color, or thickness of the lenses. It is important to understand that just having your standard plastic lenses tinted dark does absolutely nothing for UV protection. All that will do is block some visible light from getting to your eyes, but will not block any more UV than clear plastic lenses. Some options include using polycarbonate, transitions, or polarized lenses in your glasses. Polycarbonate lenses have several advantages: in addition to blocking UV light, they make your lenses thinner, impact-resistant, and come inherent with a scratch-resistant coating. Transition lenses are also an option; these lenses become darker outside and clear indoors, and come with UV protection in the lenses. Polarized lenses for your sunglasses, with an inherent UV block, eliminate glare, can be tinted gray or brown, and are great for overall outdoor comfort, especially if you participate in snow or water sports.

Most, if not all, non-prescription over-the-counter sunglasses have UV protection in them. Even the inexpensive child and adult sunglasses found at local discount stores will still have this protection. The primary difference between the high quality sunglasses and the lower quality is in the craftsmanship and optics of the lenses. For example, some of the brands in our office like Maui Jim and Oakley have polarized lenses and an anti-glare coating that provides clear and sharp vision while outdoors. In addition, we can make them in prescription and adjust them to fit you specifically, just like your regular glasses.

I believe it is a good idea for all kids and adults to have some sun protection for their eyes. I like to call UV protection “suntan lotion for the eyes”. We are trained to put on suntan lotion when outdoors for a period of time, and we need to start doing it more for our eyes.

Dr. K. at Alamo Optometry is your hometown eye doctor for outstanding service, vision care, and designer eyewear. He can be reached at 820-6622.

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