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Sunglasses

Wednesday, 8 April 2009 | Tags:

We all need sunglasses, whether running around town, up a mountain or down a hill. Plus, a good pair will help protect your eyes from sun damage and reduce squinting (and wrinkles). Here are some buying tips.

The Basics

  • The sun’s UVB rays produce tanning of the skin and can also cause skin cancer and several eye diseases and ailments (e.g. cataracts). UVA rays are also harmful to the eye.

  • In terms of UVA/UVB protection, today’s sunglasses have come a long way. Many inexpensive brands provide UV protection. They don’t all block the same amount however.

  • Voluntary industry standards for manufacturer labelling are set by the American National Standards Institute, the UV Labeling Program of the Sunglass Association of America, or the CSA Standard Z94.5-95 for Nonprescription Sunglasses published by the Canadian Standards Association. Sunglasses complying with these standards have tags or stickers that tell you in which group the sunglasses belong:

    • Cosmetic sunglasses are usually lightly tinted for use in non-harsh sunlight, and block anywhere between 0 and 60% of UVA. They must also block between 87.5 and 95 per cent of UVB. Cosmetic lenses are not recommended for driving unless specifically indicated by the manufacturer.

    • General Purpose sunglasses must block between 60 and 92% of UVA and 95 – 99% of UVB. Wear these sunglasses on days when harsh light from the sun forces you to squint, and when driving.

    • Special Purpose sunglasses may block up to 98.5% UVA and at least 99% UVB. They may be labeled as suitable for high and prolonged sun exposure.

  • If you spend extended periods of time in an environment with intense glare, like on snow or water, then glasses that block blue light are recommended.

  • Choose lenses that are dark enough to counteract brightness, but not so dark as to interfere with vision. The brighter the environment, the darker the lenses:

  • Regular lenses reduce brightness of everything uniformly.

  • Polarized lenses work specifically to cut glare that bounces off water or snow, or the road and other cars while driving.

  • Photochromic lenses change colour or tint according to the amount of light (UV) cast on the lens. More UV means the lens darkens.

  • Flash or mirror lenses reflect all or part of the unwanted light rather than just absorbing it like reglar lenses do. The metallic coatings can scratch easily.

  • Sunglass lenses come in a wide range of colours.

    • Gray lenses are a good basic choice because they darken evenly and don’t distort colour. They work well for land sports like golf, running, and cycling.

    • Higher contrast lenses like brown or amber are good for water because they block blue light and increase clarity of distant objects in blue haze, but may not reduce intensity of the light enough for some people.

    • Highest contrast colours like yellow and orange and are good for cloudy days and activities in bad weather, and are used by pilots and skiers.

  • Sunglasses are made from a variety of material:

    • Glass isn’t commonly used anymore. They don’t scratch much, but are heavy and fragile.

    • Plastic lenses are the norm these days. Thin lenses are always made from plastic as it is tougher than glass and thus more resistant to breakage.

    • Polycarbonate is a type of plastic popular in sport sunglasses because it’s particularly tough and can withstand more impact than regular plastic. Get the kind with a scratch-resistant coating.

  • Frames are typically made from either plastic or metal. Plastic is more flexible than metal and is a good choice for sports.

  • Many frame styles still allow for a lot of sun to get in around the sides. For children and those who spend extended periods of time in the sun, look for wraparound or sideshield sunglasses, but make sure the wraparound arm doesn’t impair your peripheral vision.

  • Fit is important yet simple:

    • First, try them on for comfort, paying attention to behind the ears and across the nose. Make sure when you tilt your head forward that they don’t slide down. Glasses with plastic nose-pieces minimize slippage.

    • Frames should sit straight on your face, even though they may not sit straight on the table. Many of us have one ear lower than the other!

    • The arms of the sunglasses should not stick out the back of your head, through your hair or below your ears. Most arms can be heated and bent to suit your head shape.

  • Check lenses for distortion before you buy. Distortion can cause eyestrain and headaches. To check, put them on and look at a rectangular pattern such as floor tiles. Move your head up and down and side to side. If the lines stay straight, the distortion is negligible.

Other Considerations

  • Children should start wearing sunglasses as early as possible.

Be Aware

  • With polarized lenses, LCD displays (e.g. digital cameras, PDAs, car dashboards) can be invisible.

  • The frames of glasses can stretch. To minimize this, try to avoid wearing your sunglasses on the top of your head.

OUR TOP PICK

Finding the right sunglasses for your face and needs is a personal thing. But if you’re like us, you often lose your sunglasses, so consider how much you spend. Also, keep them in a case to prevent scratches.

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