Choosing Eyeglass Lenses: Is UV coating important?
When buying eyeglasses, you may be confused by the number of options you are presented with. Once you’ve chosen your frames, you will need to decide if you want any of a number of available coatings for the lenses. These choices involve coatings that protect you from the sun’s rays, but it is important to understand the difference and why UV protection is particularly important for your eyes.
The sun’s ultraviolet or UV rays are damaging both to the skin and the eyes. For the skin, UVB rays are the most dangerous, but for the eyes, the UVA rays are equally damaging. There is also a third type, UVC, but these are generally blocked from us by the ozone layer. This situation could change in the future, however, due to ozone layer depletion.
UVA and UVB Rays
You don’t have to understand all of the science of light rays to know that it is important to protect your eyes from the sun. Without protection, UVA rays can penetrate your eyes down to your retina, while UVB rays that do not penetrate as deeply can still cause cataracts, macular degeneration and a condition called pterygia, which is the presence of visible growths on the surface of the eye. UVB rays also cause the effect of being “snow blind,” which is technically a corneal inflammation called photokeratitis.
Most people put on sunglasses on sunny days simply because it is more comfortable and they can see more clearly with them on, but it’s important to understand that eye protection from the sun’s rays is necessary for much more important reasons than simple comfort. The sun is present in the sky even on cloudy days, so your eyes should have UV protection no matter what the weather.
Blue Light
Today many of us spend a lot of time looking at computer, tablet or cell phone screens. This type of light can also be damaging to the eyes. Screen light is generally called blue light, and it is not the same as the sun's UV rays. Excessive exposure to blue light can add to the overall problem of damage to the eyes from exposure to various types of light both indoors and out.
Photochromic Lenses
UV coating should not be confused with photochromic treatment. Photochromic lenses are the type that darkens gradually when exposed to sunlight, and return to normal when you go back indoors. UV coating alone does not provide this color change. UV rays are invisible, and UV coating does not block out visible light. Photochromic lenses block visible light to make things look darker the way that sunglasses do.
One limitation of photochromic coating is that because most car windshields have UV protection built in, photochromic lenses don't darken while you are driving or in the passenger's seat of a car. It is often necessary for drivers with who have photochromic glasses to wear additional visible light protection glasses like sunglasses.
Prescription Sunglasses
Another option for people who wear glasses is prescription sunglasses. Someone who wears glasses may have a hard time finding comfortable and attractive sunglass options. Sunglasses that are designed to fit over eyeglasses are often bulky, and clip-on lenses can scratch the lenses of your glasses or not fit correctly. Prescription sunglasses offer clear vision, full UV protection and visible light protection in one pair of glasses.
Contact lens wearers should always wear sunglasses when outdoors, and for even more UV protection, it is possible to purchase contact lenses that have UV protection built in. Contact lenses do not cover your entire eye, however, so wearing sunglasses with contact lenses is always best.
Remember that not all sunglasses are alike. While it may be tempting to purchase inexpensive sunglasses, you should look for certain things when shopping for sunglasses to make sure that they will actually protect your eyes from the sun’s harmful rays. Choose sunglasses that have a sticker or tag that indicates how much of the sun’s UV rays they block. Sunglasses should block at least 99 percent of the sun’s UVA and UVB rays, and screen out 75 to 90 percent of visible light. Sunglasses come in many lens colour options, and while this is to some extent a matter of personal preference, grey lenses are best for allowing you to see colours properly. Also keep in mind that wraparound sunglasses are the best for fully protecting your eyes.
Prescription vs Inexpensive Sunglasses
The difference between prescription sunglasses and inexpensive over the counter sunglasses is how the UV protection is added. In inexpensive sunglasses it can simply be a coating on the surface of the lens. This will wear off over time so even if the lenses are labeled as 100% UV protection this will diminish over time. Good quality sunglasses have a UV film embedded in the lens so it is protected. It will not change over time and will continue to offer the same level of UV protection.
Protect Eyes At An Early Age
Protecting our eyes from the damaging rays of the sun is important from the time we are babies and first exposed to outdoor light. Parents should be certain to protect their children’s eyes by having them wear hats or sunglasses when they are old enough. Children are susceptible to greater UV damage to their eyes than adults because the eye’s lens is clearer in children. This allows the UV rays to penetrate even more deeply. We spend our lives in danger of the sun’s rays, so the habit of wearing proper eye protection should start at an early age so it will last for a lifetime.
It’s Not Too Late
People who wear eyeglasses are usually protected from UV light because most glasses come UV protection built in. If your glasses are a type that do not have UV protection be sure to ask us about having UV coating added.
Stop by our office to see our large selection of frames and let us help you pick out the best lenses for your needs.