The Right Type of Sunglasses: What’s the Difference?
Apr 03, 2014 • 99 VIEWS • All articlesLASIK & vision facts

The Right Type of Sunglasses: What’s the Difference?

Sunglasses aren’t just for fashion. The right pair provides excellent protection against glare, ultraviolet rays, and everyday physical hazards, but not all kinds are created equal. Knowing what type of sunglasses to look for—and what defense they offer—is critical before making a purchase.

UV Protection

The most important defense any pair of sunglasses can offer is against ultraviolet (UV) rays. There are two types of UV rays that penetrate the atmosphere: UVA and UVB. Of the two, UVB is far more dangerous, since long-term exposure can cause permanent retinal damage. Sunglasses with a UV coating block UVB rays, preventing them from reaching your eyes. Good-quality lenses provide 100 percent UV protection, in addition to other benefits such as dark tint or a mirrored finish. Never assume that price equals quality; a $200 pair of sunglasses may be no better than a $10 pair. Always look for a label on the packaging or the glasses themselves indicating they block UV light—some pairs block not only UVB but UVA and blue light. Defense against all three types better protects your eyes and can improve visual contrast. Generally speaking, these sunglasses are worth the cost.

Glare and Gradients

The type of sunglasses you choose may also have one or more other protective features, such as amber-coloured lenses that limit blue light and improve contrast. These are often used by hunters, skiers, and pilots. Mirror-finish sunglasses have a shiny surface coating that reduces the total amount of light entering your eye; the same effect can be achieved with a darker tint. Anti-reflective sunglasses have a coating on the inside lens surface that minimizes light reflected into your eyes. Polarized lenses, meanwhile, work by reducing horizontal light scatter—this occurs when light bounces off a smooth surface; instead of scattering equally in all directions, light tends to run horizontally, causing glare. Using polarized glasses eliminates this glare but can make it more difficult to see LED displays such as those on phones or car dashboards.

If you spend large amounts of time behind the wheel, you may want to consider gradient sunglasses, which have a dark tint at the top and are brighter at the bottom; this helps protect from top-down light. Double-gradient sunglasses have a dark tint at both the top and bottom—great for a day at the beach when both sun above and water below provide glare. Finally, photochromic lenses automatically adjust their tint level based on the amount of UV light in the environment. If you choose a pair of photochromic lenses, make sure to test them for transition speed—cheaper pairs may take a long time to lighten or darken, making them a liability.

Impact Protection

All sunglasses made in Canada and the United States also have to meet a minimum standard of impact protection. This means under normal conditions they won’t shatter and damage your eyes if struck. Plastic or polycarbonate lenses offer improved shatter protection over actual glass, but they cannot provide the same level of scratch resistance. Although sunglasses shouldn’t be confused with protective eyewear such as ski goggles, hockey visors, or safety glasses, they are nonetheless better than an unprotected eye.

General Use

Everyone should wear sunglasses when outside, driving a vehicle, or in any situation with high glare. Sunglasses are also critical if you’ve had any kind of laser vision correction performed on your eyes; both to protect your eyes and your investment. It is for this reason it’s recommended to always wear sunglasses if you’ve had Standard, or Advanced Custom Wavefront LASIK.

Not all sunglasses offer the same level of protection. While style and price are important considerations in any decision, make sure you know what kind of UV and glare reduction is offered by any type of sunglasses before you make a purchase. Just like laser vision correction, you want the best balance of price and performance.

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