Understanding the Difference Between 100% UV Protection & Polarized Sunglasses

When we get a sunburn, it’s the ultraviolet light that causes the burn, so it’s no secret that ultraviolet rays can be harmful. It’s also no secret that too much exposure to ultraviolet light over time can cause changes in the skin and even skin cancer. But did you know that ultraviolet light can also affect your eyes? Studies have shown that prolonged exposure to UV rays can lead to:

  • Cancerous changes to the skin on the eyelids
  • Changes on the surface of the eyes, like Pingueculae and Pterygium
  • A type of corneal sunburn called Solar Keratitis
  • Cataracts
  • Macular degeneration
  • Cancers inside the eye like Choroidal Melanoma

Now that summer is upon us and we’re all spending more time outdoors, it’s good to remember that the eyes need protection from UV light. Since Ultraviolet light exposure is almost always greater at higher altitudes, and since Calgary is at a moderately high altitude (1,048 meters, or 3,438 feet), it’s even more important where we live.

Calgary enjoys an average of 333 days of sunshine each year, totalling 2396 hours. That’s a lot of sunshine to make us feel light-sensitive! This highlights the importance of having adequate eye protection while we’re out enjoying the sunshine and warm weather.

Two types of sunglasses are 100% UV protection and polarized sunglasses. In this article, we address the important differences between the two.

What Are 100% UV Protection Sunglasses?

Sunglasses with 100% UV protection are designed to block 100% of harmful ultraviolet (UV) rays from the sun. These rays are invisible to the naked eye and can be damaging to both the eyes and the skin. There are three types of UV rays: UVA, UVB, and UVC.

  • UVA (Ultraviolet A) - UVA rays have longer wavelengths and can penetrate deep into the skin and eyes. Prolonged exposure to UVA rays can lead to premature skin aging, wrinkles, and an increased risk of skin cancer. They can also contribute to certain eye conditions like cataracts and macular degeneration.
  • UVB (Ultraviolet B) - UVB rays have shorter wavelengths and primarily affect the outer layers of the skin and eyes. Overexposure to UVB rays is the main cause of sunburn and can also lead to skin cancer, cataracts, and other eye issues.
  • UVC (Ultraviolet C) - UVC rays have the shortest wavelengths and are the most harmful, but fortunately, they are almost entirely absorbed by the Earth's atmosphere and do not reach the surface.

Sunglasses labeled as providing 100% UV protection are equipped with lenses that block both UVA and UVB rays. The lenses contain special coatings or additives that filter out these harmful rays, preventing them from reaching your eyes and reducing the risk of eye damage and related issues.

Expert Tip: A common misconception about sunglasses is that they should only be worn in the sun, but it’s equally as important to wear sunglasses in the shade as UV rays reflected from other surfaces are dangerous.

What Are Polarized Sunglasses?

Polarized sunglasses are a type of eyewear specifically designed to reduce glare from surfaces like water, snow, glass, and other reflective surfaces. They achieve this by incorporating a special polarizing filter into the lenses.

Glare occurs when light waves from the sun or other sources reflect off a flat surface and become aligned in a horizontal pattern. This concentrated, intense light can be uncomfortable and harmful to the eyes, causing eyestrain and reducing visibility. Polarized lenses work by blocking these horizontally oriented light waves while still allowing vertical light waves to pass through.

The polarizing filter in the sunglasses lenses is usually using a chemical film that is vertically aligned. When horizontally polarized light hits the filter, it cannot pass through, effectively reducing the amount of glare that reaches your eyes. This enhances visual clarity, reduces eye strain, and improves overall comfort when dealing with intense light conditions.

Polarized sunglasses are particularly popular among outdoor enthusiasts, such as fishermen, boaters, skiers, and drivers, as they help to provide a clearer view of their surroundings and improve safety. However, it's essential to note that polarized sunglasses may not be suitable for certain activities, such as viewing LCD screens or some instruments, as the polarization can interfere with these displays.

When choosing polarized sunglasses, make sure to get them from reputable brands and retailers to ensure the lenses effectively block glare and provide the intended benefits.

Expert Tip: Digital screens emit polarized light, so Polarized Sunglasses block out parts of the image and are not ideal for digital devices. Also, Polarized Lenses eliminate reflections from the surface of a puddle on the road, creating a risk for motorcyclists and cyclists. Elite golfers who judge the lay of the green by the reflection of the surface of the blades of grass will notice that this is more difficult wearing Polarized Lenses that eliminate these reflections.

UV-Blocking Sunglasses vs Polarized Sunglasses: Which is Right For You?

Light sensitivity comes from two sources: UV exposure and glare. Since there are negative health effects from Ultraviolet light exposure, all sunglasses sold in Canada must be UV-blocking, by law. That’s not necessarily true at the swap meet on your tropical holiday, though. The good news is that UV Protection is part of every pair of Sunglasses purchased at Doig Optometry. We can also ensure that your clear eyeglasses are UV-blocking.

Since there are no negative health effects from glare, there’s no legal requirement that your sunglasses eliminate glare. Patients who still experience light sensitivity in their UV-blocking sunglasses sometimes think that their sunglasses aren’t dark enough. However, it’s more likely that the remaining light sensitivity is actually glare sensitivity, which can be eliminated with a quality pair of polarized sunglass senses.

UV Blocking Sunglasses protect your eyes from dangerous ultraviolet rays and are crucial to good eye health. Polarized Sunglass Lenses can make your eyes more comfortable by eliminating glare. Whether you are deciding between simple UV-blocking sunglasses or Polarized Sunglasses, one of our friendly and helpful team members will help you find the best lenses for you. See Sharp, Look Sharp, Love Your Glasses®!

To find the right sunglasses for you, call Doig Optometry today for a consultation!

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