How Do Polarised Sunglasses Block UV Rays?

Woman wearing polarised sunglasses

Let’s get one fact straight:

We all know that wearing polarised sunglasses is vital, in any weather condition! They don’t just cut out the glare from the sun, but a good pair adds to the vision positively!

But have you wondered how your sunglasses do all of that:

Apart from making you look cooler, of course? So, here it is. Sunglasses aid in about four things and they are:

The main bit:

Your trusty pair of shades will help you block ultraviolet rays (UV) from the sun, you knew that, right?

UV rays (over a long period of time) can damage/harm your corneas, and weaken your eyesight. But if you have a good pair of polarised sunglasses, it will help filter that out.

What are UV Rays?

The effect of UV Rays

UV rays are present in the sun and constitute about 10% of the sun’s total light volume. There are two types of UV rays: UVA (this is the one responsible for skin cancer and premature ageing) and UVB (responsible for sunburn). Both types have higher frequencies than the visible light our eyes can perceive. They damage our eyes the same way they damage our skin, even in the shade reflected rays pose a threat to our eyes.

Polarised sunglasses protect from intense light

Duke Glassic

This is one of the main purposes of sunglasses:

To put things into perspective, it’s vital to understand how light functions. As we all know that sunlight is the main source of light, right? When it reaches the earth, sunlight is absorbed, reflected and refracted in all elements we see—elements are water, glass, plastics, and the ground.

But here’s the kicker:

Once it’s reflected, this light travels in a horizontal direction and enters our eyes, causing visual uneasiness, and in some cases, even temporary blindness. We have all been in situations when surplus sunlight has hindered the view especially near lakes or the beach, right? This situation can be eluded with sunglasses.

“We have all been in situations when surplus sunlight has hindered the view especially near lakes or the beach, right? This situation can be eluded with sunglasses.”

Polarisation—a way to cut glare and UV Rays

How sunglasses work

Light waves vibrate just like sound waves do. When a group of light waves come together but are travelling in different directions, a glare occurs. Polarisation filters built into sunglasses (a film sandwiched in between the lenses) are made up of molecules that adjust the light waves with each other and eliminate the glare.

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What are the key advantages of polarised sunglasses?

Glare can cause strain in your eyes. And polarised sunglasses can offer better visual comfort and clarity, by cutting that out. For drivers going on road trips in the summer, polarised sunglasses reduce glare from the vehicle’s hood or smooth road surfaces. There are similar effects when you are near water bodies.

Sunglasses eliminate specific frequencies of light

As noted before, sunglasses can eliminate specific frequencies of light. Certain light frequencies can cause blurred vision, while other frequencies enhance the contrast between colours. Choosing the right colour for your sunglasses lets them work better in specific situations.

Tints on sunglasses determine the amount of light

You may be familiar with polarised lenses that come with colour gradients or tints, such as green, yellow or blue. They’re not just for looks, tints provide extra protection from overhead sunlight when you are driving, allowing enough light to filter through the bottom so that you can see where you’re going.  

Polarised sunglasses

Different tint colours are suitable for different environments. Sunglasses with yellow tints are great for foggy or low light conditions, while frames with brown tints are suitable for the sunny weather.

Light waves vibrate just like sound waves do. When a group of light waves come together but are travelling in different directions, a glare occurs. Polarisation filters built into sunglasses (a film sandwiched in between the lenses) are made up of molecules that realign the light waves with each other and eliminate the glare.

To wrap things up, here are some questions we would like to answer:

If the sun doesn’t bother my eyes, do I still need to wear sunglasses?

Yes. You should. The effect of UV rays that can cause problems like Photokeratitis, Pinguecula and permanent retinal damage.

What exactly are UV Rays?

UV rays are present in the sun are constitute about 10% of the sun’s total light volume. There are two types of UV rays: UVA (this is the one responsible for skin cancer and premature ageing) and UVB (responsible for sunburn).

When do UV Rays affect my eyes?

The sun’s rays are strongest between 10 am and 2 pm, but that’s not the only time UV rays can affect your eyes.

Can certain medical problems increase my risk for damage from UV rays?

Yes. People with cataracts (and those who have had cataract surgery), macular degeneration or retinal dystrophies should be extra careful.

What are the options to prevent UV damage to my eyes?

You must wear sunglasses to prevent damage to your eyes. While some contact lenses provide UV protection, they don’t cover your whole eye, so you still need sunglasses.

Do darker sunglass lenses provide more UV protection than lighter lens tints?

Darker sunglasses decrease the amount of visible light that passes through the lenses compared with lighter lens tints, but they don’t necessarily provide greater protection from UV rays. For 100% UV protection check and see if you can get sunglasses that are 100 polarised.


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