Often I have patients who buy sunglasses at a drugstore, at the beach,etc. -then start to wonder about the quality of the lenses.The sun is so bright in the mountains around Fort Collins it’s hard to get by without something when you forget. Optics aside (we know they are often poor even in very inexpensive sunglasses off a rack), the question is do they provide adequate protection from ultraviolet radiation (UV). UV is divided into 3 bands; UV-C is mostly absorbed by the atmosphere and not a concern, UV-B passes into the eye and causes the most problems, UV-A adds to this damage. Visible blue light is the one that snuck up on us-studies are still showing contradicting results but it does appear regular blue light like you see outside every day causes retinal damage and on a cumulative basis, kind of like radiation exposure. Macular Degeneration is a leading cause of blindness in seniors so it is an important issue.
The American National Standards Institute (ANSI) is a private non-profit organization that administers and coordinates the U.S. voluntary standardization and conformity assessment program. ANSI developed a standard for non prescription eyewear (Z80.3 – 2008), Nonprescription Sunglasses and Fashion Eyewear – Requirements). One safety issue that consumers do tend to be aware of is protection from ultraviolet radiation (UVA and UVB). The amount of UVA and UVB protection needed depends upon how a consumer uses the sunglasses, with two types of use classified as Normal ( home to the car to the office) or High and Prolonged Exposure (at the beach, fishing, skiing). Lenses are also classified for intended function as special, dark, general purpose or cosmetic tint. The combination of the intended function and the type of use gives a total of eight UV transmittance specifications. Sunglass manufacturers with a long track record that meet ansi standards are what you want. Since in some ways it is a voluntary system with few penalties for non-comliance or misrepresentation, the best value usually comes from known suppliers of quality (which may not be the most expensive brands). Remember, If you do choose a pair of blue sunglasses that states it blocks uv, that is all pretty meaningless (It could block 1%) and meanwhile the tint is dilating the pupil allowing more UV than normal to come in due to the dilation.Unfortunatley some of this light is now blue causing further damage. Eye Doctors Offices are very adept at providing you with UV protection in precription eyewear and you should insist it be included with your lens options. Ask advice when it comes to non prescrition lenses. Not only can you proect your eyes from damage you can insure continued comfortable contact lens wear-a case of snowblindness is a type of pain you don’t want to experience! Face wrap sunglasses, especially the type we carry that add a lite foam seal around the eyes, can be very helpful in sports activities to prevent dry eyes and stinging.