We all are cheered up by a bright, sunny day, but the effect of all that sunlight on the eyes can be very harmful to our eye health. Both UV radiation and the glare caused by sunlight can create a variety of medical issues ranging from temporarily irritating to irreversible damage.
There are basically two kinds of light that we need to concern ourselves with when thinking about choosing sunglasses ... rays that we can see (visible spectrum) and UV rays that we can't. The visible spectrum of light is what causes us to squint on a sunny day, and requires a tint on our glasses to absorb some of the light to keep us from squinting. UV light, however, is not affected by any tint on our glasses, but requires a special clear coating to absorb UV rays before they can enter our eye. So, even a very dark pair of sunglasses may not protect us at all from UV light, while a clear, untinted lens with a UV coating can block virtually all UV light!
Here are some frequently asked questions about the role of sunglasses in protecting the eyes from harm:
What are UV rays? UV stands for ultraviolet, a spectrum of light invisible to the eye. Ultraviolet light consists of UVA, UVB, and UVC rays. UVC rays are stopped by the Earth's atmosphere before they reach the eye, but UVA and UVB can both reach the eye and potentially damage it.
How does UV radiation affect unprotected eyes? UV rays can cause proteins inside the eye's lens to become opaque or cloudy, a condition known as cataracts. Cataracts can interfere with night vision, reduce your ability to see colors, and make reading difficult. Cataract changes cannot be reversed, they can only be surgically removed. UV rays can damage the neurological inner layer of the eye called the retina, and can also cause a temporary but extremely irritating "sunburn" of the outside of the eye called photokeratitis.
How do I know my glasses will protect my eyes? Choose sunglasses that claim to block at least 99 percent of UV rays -- UVA as well as UVB. Look for a label reading "UV 400," since this designation means that the glasses block UV rays as small as 400 nanometers, providing 100 percent eye protection. But don't forget, you should put UV protection on all your glasses since the UV coating is clear, To protect your eyes from the glare caused by visible light, you will need a sunglass tint. A gray tint tends to distort colors less than other color tints, but if that's not a concern, any dark color tint will do. The tint color and density you choose should block 75 to 90 percent of visible light.
What are polarized lenses? Polarized lenses are specially designed to filter out certain types of glare that tend to radiate upward from horizontal surfaces when sunlight reflects off of them. They are recommended for tasks such as boating, fishing, skiing, golfing, jogging, and driving. Most polarized lenses will bear a label identifying them as such.
What types of glasses can I choose from? We are able to provide you with a wide range of stock sunglass options from well-known sunglass manufacturers like Bausch & Lomb and Maui Jim.. If you normally wear prescription glasses, you may be happy with a non-prescription pair of "clip-ons" or wraparound glasses that simply fit over your lenses. If you prefer, we can make prescription sunglass lenses, including polarized, for a frame of your choosing. We can also provide you with lenses that darken when exposed to bright light that go by the trade names "Photogray" and "Transitions".
What additional types of protection should I consider? If you're concerned about the light that can "leak in" through the sides or top of your sunglasses, you can wear a broad-brimmed hat to reduce some of this exposure. If you wear contact lenses, you may want to consider getting contacts that have a UV-blocking filter in them. These UV-blocking contacts can be worn along with a good pair of non-prescription sunglasses for optimum eye protection.
If you want to know more about choosing the right sunglasses, with or without prescription lenses, please call our office. We're happy to help!