Choosing Sunglasses

March 16, 2004

Consider this question. What’s more important to you: warm and dry feet, a comfortable pack, a breathable rain jacket, or your eyesight? Not a difficult decision, is it. So why do so many of us gladly dish out for the best shells, packs, and boots, only to put little or no thought into our eyewear?  

Now ponder these facts: The cornea is 300 times more sensitive to sunlight than skin (which we grease up with protective sunblock without second thought). Overexposure to sunlight can cause eye disorders including cataracts, damage to the cornea and retina, and snow blindness. According to a 1998 report from the Journal of the American Medical Association, exposure to even low amounts of sunlight increases the risk of eye damage.  

Sunlight exposure increases about 10 percent for every 3,000 feet of elevation gain, and is most severe between 10 a.m. and 4 p.m. Reflective surfaces magnify the hazard even more: Fresh snow reflects 85 percent of sunlight, water reflects 20 percent, and sand 35 percent.  

Prolonged exposure to sunlight’s visible spectrum can cause dizziness, discomfort, strain, a temporary reduction of vision, and even pain, but the primary threat to our eyes is invisible ultraviolet, or UV, light. And the danger is not just on bright, sunny days — the majority of UV light penetrates cloud cover as well. 

The answer is simple and familiar: sunglasses. But not just any shades will protect your eyes properly — you need sunglasses that block UV light. The U.S. Food and Drug Administration (FDA), which regulates sunglasses, advises looking for a label that specifically states that the sunglasses offer 99 to 100 percent UV protection. Sport sunglasses, those made for outdoor activities with more durable frames than fashion sunglasses, also generally block 75 to 90 percent of visible light, depending on whether you want them for low-light, moderately bright, or very bright situations. Tinted sunglasses that don’t block UV can be worse than no protection at all, causing the pupil to dilate and allowing even more harmful rays to enter your eye.  

Everyone needs eye protection, especially kids. With wider pupils and more sensitive ocular tissues, children’s eyes are more affected by sunlight than those of adults. Some sunglasses are designed for the smaller faces of children, like the Julbo Peekaboo ($30, for age 6 – 10) and Spot ($25, for age 3 – 6). Both extend to the eyebrow for greater protection, because kids frequently look up.  

Price isn’t a barometer of eye protection — $20 shades can offer UV protection, as long as they’re so labeled, provide full eye coverage (see below), and haven’t been scratched or otherwise distorted. So what do you get when you spend more? Having used numerous models of sunglasses in a range of prices, what I’ve typically noticed with the more expensive versions is superior clarity in a broader range of light conditions, sturdier frames, better polarization (meaning less glare), and a closer fit that keeps the frame from sliding down my nose. For instance, the Kaenon Kore ($180) has a pliable frame that stays put on my face, provides excellent clarity in shade and bright sunshine, and comes in three sizes.  

Besides UV protection, here are a few other factors to consider as you outfit your eyes this season.  

Sunglasses are ineffective unless they fit well. They should not slide down your nose even with abrupt head movements and should protect your eyes from light and wind on all sides — an ideal fit will have no gaps between the frames and your face, but still provide enough space for your eyelashes to move without brushing the lenses. Wrap-around models are most effective, like the Kavu Perma Grin ($82 polarized, $64 non-polarized), which give me full eye coverage when I’m cycling and backcountry skiing. Rubber patches on the frames also effectively keep shades stuck to your head, and pads at the ears enhance comfort. Two models I’ve used shine in this regard: the Oakley Half Jacket XLJ ($100 to $145, depending on frames and lenses) and the Action Optics Vector ($135 to $160) both have excellent pads at the nose and temples that are comfortable and keep the sunglasses glued to my head in any activity.  

Whether metal or plastic, the frames should be built to withstand some abuse; check them out before buying, and reject any that appear flimsy. Sunglasses typically break at the hinges; metal frames and hinges are most durable, though lighter-weight plastic frames can be more comfortable to wear and often stay in place better.  

Lens Material
Lenses are made from either glass or polycarbonate — i.e., plastic. Glass offers superior optical quality and is more scratch-resistant, but polycarbonate lenses are less expensive, lighter weight, and much less likely to shatter — important in activities that could involve an impact, like competitive sports, skiing, and cycling.  

Lens Color and Clarity
Green, brown, and smoked (gray) tints are best for bright sunlight. Warm lens colors like orange, brown, yellow, and red improve depth and detail perception, while cool tints like gray and gray-green are easier on your eyes but flatten light, affecting depth perception. Blue works best in moderately bright light, such as hazy sunshine. Yellow and orange are best for low-light situations like mountain biking in the woods.  

Polarized and Photochromic Lenses
Available in any color and darkness, polarization reduces glare off reflective surfaces like water, ice, snow, roads, cars, and even buildings, and is always worth looking for, though it increases cost by $30 to $50. Polarization increases visual acuity and reduces the eye fatigue and discomfort caused by glare. Models like the Bollé Slice ($60 to $100) are made for high-glare conditions such as sea kayaking in bright sun; a coating on the backside of their polycarbonate lenses even eliminates light reflection off your face back onto the lenses.  

Photochromic lenses adjust to the amount of light present, and are good for outdoor activities involving significant shifts in light or for transitioning from indoor to outdoor conditions. They’re useful with prescription sunglasses, but are only available in glass.  

Interchangeable Lenses
Some models come with two to four different sets of tinted lenses that can be readily changed to accommodate varied light situations. The lenses should pop in and out easily, not get scratched in the process, yet be secure when in the frames, as with the Julbo Reflex ($89), which has four interchangeable polycarbonate lenses for various conditions.  

Some sunglass manufacturers rate their lenses according to a standard adopted in Europe in 1995, which created five categories of protection. Category 0 is clear or slightly tinted lenses (80 to 100 percent of visible light transmitted); 1 is slightly tinted, for partially obscured sunlight (43 to 80 percent transmitted); 2 is a medium tint for average sunlight (18 to 43 percent transmitted); 3 is a dark tint for strong sunlight (8 to 18 percent transmitted); 4 is very dark for exceptionally strong sunlight—think glacier goggles, not driving shades (3 to 8 percent visible light transmitted). Sport sunglasses will generally fall within category 2 or 3, or category 4 for the very darkest models.  

Take time to get the right sunglasses with the right fit. Your eyes will thank you for it.

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Michael Lanza

AMC Outdoors, the magazine of the Appalachian Mountain Club, inspires readers to get outside and get engaged. Learn more.