Sun protection, which includes the use of sunglasses, is one of the Ten Essentials. No wonder. Sunglasses protect your eyes from harmful ultraviolet (UV) rays, reduce eye strain in bright conditions and protect you from flying debris and other hazards.
The material used in your sunglass lenses will affect their clarity, weight, durability and cost.
All sunglass lenses are tinted to cut down on overall brightness and enhance terrain definition. But your choice of tint colors affect your vision by influencing 1) how much visible light reaches your eyes, 2) how well you see other colors, and 3) how well you see contrasts.
The more expensive the sunglasses, the more likely it has several layers of coatings. These can include a hydrophobic coating to repel water, an anti-scratch coating to improve durability and an anti-fog coating for humid conditions or high-energy activities.
Two methods are commonly used. Lenses made via the injection process offer the best in optical clarity, but are more expensive. The bent-sheet process is used to make both performance and inexpensive glasses. High-end styles use a longer process to offer similar optical clarity as injected models, while lower-cost styles used a simplified process that yields a bit less clarity.
Some styles come with interchangeable (removable) lenses of different colors. These multi-lens systems allow you to tailor your eye protection to your activities and current conditions. Consider this option if you need reliable performance in a wide variety of situations.
Polarization is a great feature if you enjoy water sports or are especially sensitive to glare. When light reflects off of flat surfaces, such as a lake, the light waves align in horizontal patterns, creating intense glare. The filters in polarized lenses block these horizontal light waves, substantially reducing blinding glare and its resulting eyestrain.
In some instances, polarized filters react with the tints in windshields, creating blindspots and diminishing the visibility of LCD readouts. If this occurs, you should consider mirrored lenses as a glare-reducing alternative for driving.
The method used to polarize lenses affects both the optical-quality and cost of the sunglasses.
Ultraviolet (UV) rays from the sun can damage your eyes by contributing to cataracts, macular degeneration and growths on the eye, including cancer. All of the sunglasses offered at REI block 100% of UV light.
UV protection information should be printed on the hangtag or price sticker of any sunglasses you buy, no matter where you buy them. If it isn't, find a different pair. Also keep in mind that cheap, tinted sunglasses with limited UV protection can actually do more harm than good, as they cause your eye lenses to open up wider, leaving them even more vulnerable to UV rays. Kids' eyes are especially vulnerable to UV light, since they don't have the same level of natural protection as adults.
The amount of light that reaches your eyes through your lenses is called Visible Light Transmission (VLT). Measured as a percentage, VLT is affected by the color and thickness of your lenses, the material they're made of and the coatings they have on them.
Choosing a frame is nearly as important as the lenses, since it contributes to the comfort, durability and safety of your sunglasses.
These depend on the frame material. On most nylon frames, hinges feature a molded pin that's actually part of the frame material. This creates a very durable hinge. Metal, acetate and zyl frames must use either a barrel-hinge or spring-hinge design. These offer the advantage of extra flex to fit larger heads, at the cost of some durability. Higher-quality frames may use nickel-silver hinges that are more rugged and reliable.
If you plan on working up a sweat, look for styles that have rubber nosepieces or earpieces that help keep your glasses from sliding down your nose.
Here are some tips when trying on a pair of sunglasses:
Shopping online? Look for product descriptions that include fit guidelines such as "fits smaller faces" or "fits medium to large faces" for guidance. A few brands offer temples that are adjustable or come in several lengths.
If you choose a metal or wire-core frame, you can usually adjust the fit by carefully bending the frame at the bridge and/or the temples. You may also be able to adjust the nosepieces, by pinching them closer together or farther apart, to rest on your nose more comfortably.
There are no right or wrong lens shapes, but consider these guidelines:
The American Academy of Ophthalmology advocates wearing sunglasses anytime you're outdoors, but particularly when:
In addition, if you have an eye disease, have had cataract surgery or are taking photosensitizing drugs, you should wear sunglasses whenever you go outside.
A $20 pair of sunglasses can look pretty similar to a $150 pair, so why pay more? The difference is in the technology, which offers more comfort, durability and performance. For around-town wear and while driving, an inexpensive casual pair may be all that you need. But for regular outdoor activities, especially high-impact ones such as cycling, performance glasses are usually well worth the investment.
By Steve Tischler
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Last updated: 10/05/2012
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