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HOW TO BUY SUNGLASSES ONLINE
Sunglasses are now made by hundreds of designers, in thousands of combinations. To find the best sunglasses for your needs, you should begin by defining your needs. Where will you be using your sunglasses mostly? On the water, on the beach, biking, tennis, in the car, motorcycling, golfing, or just looking good? Most people say “all of the above”, but some people are doing a lot of one type of activity.
Sunglasses made by the big fashion houses are designed for looking good, and for blocking out some sunlight. They are usually not designed for outdoor activities. The most popular sunglasses brands nowadays are Ray-Ban, Gucci, Prada, Oakley, and Maui Jim. Oakley and Maui Jim have turned activity-based sunglass designs into “cool” sunglasses, aimed at a younger crowd.
There are many different features in a pair of sunglasses, but prescription sunglasses have become very popular in the last few years. You can design your own custom prescription sunglasses in the same way that you make your own prescription glasses. Shop for a frame, add a lens with your prescription, and then pick the lens tint and coatings that are best for your needs and lifestyle. Prescription sunglasses are a great way to see in the sunshine. Prescription sunglasses can be made with single vision, bifocal, or progressive lenses, and in a variety of lens materials and colors.
Brown and gray are the most popular colors for sunglass lenses. Brown is the best color overall because it allows the wearer the widest light spectrum through to the eye, while blocking blue light and offering optimum contrast. Brown is great for applications where distances need to be constantly judged, like tennis or golf or skiing or other sports requiring acute visual perception and contrast differentiation. Brown is also best for lower light situations, like fishing in the late afternoon or early morning.
Grey tint is best for bright light situations like water sports because it blocks out the brightest of the sun’s rays. Other colors like green and blue are used more for fashion purposes than for utility. Blue is the overall worst color of all for the wearer because it enhances blue light, which creates more glare. If you like blue as a fashion choice, consider a custom-made lens tinted brown but with a blue flash mirror coating. Yellow is used to heighten contrast without blocking too much light, and it is commonly used for shooting and skiing on cloudy days. Bolle makes a special green tint that is designed specifically for tennis (the Competivision lens). The green tint helps to accentuate the yellow color of the tennis balls and make the white lines stand out.
Prescription sunglass lenses are tinted by leaving them in a bath of tint solution. The longer they are left in the solution, the darker the tint becomes. Lenses bathed in tint colors can assume just about any color shade or color density. The lens actually absorbs the tint color into the lens material. Tint density is defined as a percentage, where 0% is completely clear, and 100% permits no light to pass through (solid). A 10% to 20% tint is used for a fashion tint, and a 50% to 80% tint is used for outdoor protection from the sun. For sun protection, you would use a 50% tint for all around use, both during midday and during morning and evening hours when there is less available light. A 50% tint is a better all-around lens. For bright light situations, like midday sun on the water, an 80% tint provides maximum protection from the bright sun.
Sun-sensitive lenses are also know by the brand name Transitions, and the technical name “photochromic”. Sun-sensitive lenses automatically darken to a moderate shade when they are exposed to the ultra-violet rays of direct sunlight. When the direct sunlight is removed, the lenses lighten again. Sun-sensitive lenses are typically only available in brown and grey, but are available in the normal range of vision correction for prescription sunglasses. A photochromic lens has some limitations. First, the lens needs ultra-violet light to darken, and it will darken more slowly or incompletely if the lens is not in direct sunlight. For example, if you are wearing a hat, if it is cloudy, or if you are inside an automobile, the lenses may darken slowly or not completely. Second, it could take up to eight minutes for lenses to transition from dark back to clear. So if you are in-and-out of the sun, the lenses may not be dark or clear when you want them to be. Third, photochromic lenses do not become completely clear indoors, but retain a light tint that may not appeal to people who want completely clear lenses indoors.
Polarized sunglass lenses are tinted lenses that block vertical light from hitting your eye and causing eye strain. Hunters, boaters and fishermen, golfers, and drivers are the most common users of polarized lenses. Any surface can create glare in sunlight, including water, sand, snow, windows, vehicles, and buildings. Polarized lenses ease eye stress and fatigue in the sun, and lenses are available in several color and density options. However, in some situations, glare can be beneficial. For example, polarized lenses could make it difficult for a driver to see ice on the road, or for a skier to see ice on the ski slope, or for a seaplane pilot to see the water when landing. Polarized lenses function similar to window blinds with horizontal slats when open. You view the slats on the edge so they are very thin, and these edges hold the tint color. Polarized lenses block the vertical light that tries to enter your eye from down below or up above, and it only allow the horizontal light to pass through the lens. Polarized lenses are available in the normal range of vision correction for prescription sunglasses.
Anti-Reflective (AR) coating goes on the backside (side closest to your face) of prescription sunglasses and non-prescription sunglasses. Backside AR prevents light and glare from coming in to either side and from behind you, bouncing off the inside of the lens and into your eye. This kind of glare is very common in sunny situations, it is extremely disruptive and it is very valuable to eliminate this glare from your vision.
Clip-on sunglass lenses are tinted lenses that clip on to regular prescription glasses, effectively turning them into prescription sunglasses. The clip-ons usually match the eyeglasses frame in shape and color, and attach either by clips or with magnets. Regular clip-ons require two hands to add and remove the clips, but magnetic clip-ons (they hold to the frame with magnets instead of clips) can be added or removed with just one hand. Clip-ons have advantages and disadvantages. It is convenient to be able to convert your eyeglasses into sunglasses and back again. However, wearing a clip-on means adding a significant amount of reflected glare. Light passes through the clip, reflects off the front of the frame, reflects off the back of the clip, and bounces around in there, causing significant additional glare and eyestrain that does not occur with prescription sunglasses.
There are also sunglasses that are designed to fit over your eyeglasses, covering them completely. These “fit-overs” are useful for eyeglasses that do not have matching clip-ons, and they also serve to block out light from entering around the sides of your glasses. Side-glare is extremely annoying, especially on the water, so fit-overs may be a better solution that sunglass clip-ons.
Contributing Expert Mark Agnew is the founder and CEO of Eyeglasses.com, an online retailer of eyeglasses, prescription lenses, and
sunglasses since 1999. |
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