Sunglasses: What You Need to Know

Sunglasses are more than just a fashion statement: wearing a good pair of shades is one of the most important things you can do for your eyes. UV rays can damage eyes that aren’t protected, putting you at risk for eye disease later in life. Fortunately, CNIB has the info you need to choose sunglasses with confidence. Confused about mirror coatings? Polarized lenses? Lens colour? The difference between cheap and expensive shades? Here’s what you need to know.

Do darker sunglasses (that you can’t see my eyes through) protect from UV rays better than lenses that are lighter in colour?

No. Dark lenses don’t necessarily provide more UV protection than lighter shaded ones. While darker-tinted lenses are appropriate for very bright conditions (or for people whose eyes are particularly light sensitive), experts recommend medium-tinted lenses for ordinary, day-to-day use.

Does it matter what lens colour I choose?

Yes. For the best colour perception, lenses should be gray, amber, brown or green. The American Academy of Ophthalmology (AAO) recommends green lenses (which offer good colour contrast and minimal colour distortion) for ordinary, day-to-day use. On the other hand, red, orange, blue or purple tints can cause colour distortion and let in too much light.

Do I need expensive sunglasses or are inexpensive ones just as good?

You don’t need expensive shades. Look for a label or tag indicating the level of UV protection. A cheap pair of sunglasses offering high UV protection is a safer bet than expensive shades with low UV protection.

What percentage of UV protection should I look for in sunglasses?

There are two kinds of UV rays: UVA and UVB. CNIB recommends shades that block 99 to 100 per cent of UV radiation – and make sure that includes both UVA and UVB.

If you buy a pair of sunglasses that don’t block UV rays, you could be doing even more damage to your eyes. Sunglasses that merely shade your eyes without adequately blocking UV radiation can cause your pupils to dilate in the sun, allowing in more rays.

What is the best style of sunglasses to protect my eyes?

Large-framed, close-fitting, wraparound shades offer the best protection. The lenses should be big enough to shield your eyes from all angles (above, below, left and right) and block light coming in around the frames. If you wear shades while playing sports, make sure the lenses are made from shatter-resistant polycarbonate, not glass.

When should I wear my sunglasses? What about children?

You should wear them anytime you are outside – winter or summer – and experiencing sunlight or reflected light (for example from water or a ski hill).

Anyone who spends a great deal of time outdoors at work or play should be particularly vigilant. Shades are also recommended for people who have had cataract surgery or take certain medications, such as tranquilizers, sulfa drugs and birth control pills, which can increase the sensitivity of your eyes to light.

Children who play outdoors should also wear sunglasses. Children’s shades should be impact resistant, with bendable frames and unbreakable, polycarbonate (not glass) lenses. Get your child to try on the sunglasses before buying them to make sure they fit properly.

With UV exposure, your risk of eye disease builds over time. The more UV rays your eyes absorb over a lifetime, the greater your risk of conditions such as age-related macular degeneration (AMD) and cataracts later on. So taking steps now can really pay off down the line.

What are polarized lenses for?

Polarized sunglasses block glare caused by reflection from flat surfaces. For this reason, they are recommended for driving, boating, fishing, skiing or any other activity where there is a chance of glare from water, snow or the ground.

What about photochromic lenses that lighten or darken in response to UV light? Are they sufficient in bright conditions?

Yes, they are sufficient for bright conditions. However, be aware that photochromic lenses take a few minutes to lighten or darken when going from one light situation to another.

What about lenses that clip on to my existing glasses? Do they work?

Clip on sunglass lenses are worn over prescription eyeglasses. While handy, clip-ons might not fully cover your eyeglass lenses – be sure they do before you buy. Clip-on shades can also scratch prescription lenses or cause reflections. When choosing a clip-on shade, speak to your optician or optometrist for professional advice.

Do mirror coatings protect your eyes?

Not really. Mirror coatings consist of thin layers of metallic finishes on ordinary lenses. The mirror coating will reduce the amount of visible light hitting your eyes, but doesn’t necessarily provide greater protection from UV radiation.