Here Comes the Sun

Sunglasses are more than a fashion accessory. They’re a first-line defence against eye damage caused by ultraviolet (UV) and blue light filtering through the atmosphere. To protect your eyes, wear good-quality sunglasses and let fashion sense meet vision care.

Ultraviolet light, the invisible part of the light spectrum, comes in two forms: UVA and UVB. Both can be absorbed by the eye in much the same way they’re absorbed by the skin. While you can’t see or feel the effects of UV rays right away, by the time you reach your fifties, the eye damage they cause is permanent.

Blue light, found in the blue portion of the colour spectrum, can also harm vision. The glare from this intense light impairs the eye’s ability to focus properly. Health Canada warns that recurrent exposure to blue light—for example, in light reflecting off snow or water—promotes premature aging of the retina and increases the risk of becoming blind.

Different light, different damage

As the eye absorbs light, heat is generated and a chemical reaction takes place in the eye tissue. Prolonged exposure to both UV and blue light over time overwhelms the eye’s natural ability to heal itself, leading to permanent damage.

The type of damage to the eye depends on the type of light.

• UVB rays are absorbed by the cornea and conjunctiva, a membrane that covers the outside surface of the eyeball, and are less damaging than UVA rays.
• UVA rays are absorbed by the lens, which hastens the formation of cataracts, causing cloudiness, dim vision, colour fading, and increased light sensitivity.
• Blue light is absorbed by the retina, the lining at the back of the inner eyeball that controls visual acuity. It speeds up retinal damage and can result in age-related macular degeneration (AMD), the leading cause of severe eyesight loss and blindness among middle-aged and older people.

Who needs protection?

Everyone who works or plays in the sun needs eye protection. If you’re taking photosensitizing drugs, you have to be even more careful. Older people and those with lighter-coloured eyes are more at risk because they have less melanin, which acts as the body’s natural sunscreen protection.

Working with computers and/or under bright fluorescent fixtures can also damage eyes. For indoor use, wear sunglasses with an invisible UV protective coating that has a clear lens colour.

We’re exposed to harmful UV light on overcast and hazy days, not just sunny ones, so grab your sunglasses and protect your eyes.

Levels of sun protection

When choosing sunglasses, look for those that offer proper UV and blue light protection for the level of sunlight and your activities. Use Health Canada’s three grades of sunglasses to select the best type. Keep in mind that labelling standards are voluntary.

Note: some sunglasses are now labelled UV400; they offer full protection against UV rays.

Tips on choosing the right sunglasses

Once you’ve decided on the level of UV protection, check out the type, quality, and colour of the lenses.

• Choose lenses that are dark enough to stop you from squinting against bright light, but not so dark that you have trouble seeing, especially if you’re driving.
• Select blue blockers with amber, grey, brown, or green lenses, in a medium to dark tint if glare from snow or water is a problem. Polarizing lenses are also a good choice to cut glare, as long as they also have UV protection.
• Pick plastic or mirror lenses with a scratch-resistant coating. Without this coating they can scratch easily, allowing light to filter through.
• Be wary of cheap drugstore glasses whose thin lenses warp easily, causing vision distortion. To test, look at a rectangular pattern when trying on the sunglasses, moving your head up and down and sideways. If the lines distort, the glasses can cause eye strain. Choose thicker, impact-resistant lenses that hold their shape.
• Wear wraparound glasses that cover your temples and prevent rays from entering from the sides if you’re light sensitive or spend a lot of time outdoors.

Already wear prescription glasses? Consider photochromic lenses, which react to the sun’s intensity by automatically darkening, creating built-in sunglasses.