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Rules of the Road

Can You Drive With Sunglasses?

February 13, 2024

5 min read

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Sam Plant

Content Writer

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When Emperor Nero first watched gladiator battles through an emerald, he probably didn’t realise that, 2000 years on, we’d be using a similar technique to avoid sun glare when travelling through the streets in coloured metal boxes. But sunglasses are now an essential driving accessory, helping keep us safe in low or bright sun, wet and snowy conditions, where dazzle is most likely to cause accidents.

They come in every shape, size and style, but when you’re using them behind the wheel, some sunglasses are superior — and others not suitable at all. Here’s what you should look for when choosing a pair of driving sun-specs — and when you should ditch them altogether, in favour of natural light.

Driving in sunglasses: the rules

girl sitting on car wearing sunglasses

Dazzled by the sun? The Highway Code rule 237 recommends slowing down, and, if necessary, pulling over until you can see properly again. But sunglasses can help to prevent things from getting this bad.

As your vision is your most important sense as a driver, it’s important that anything you wear enhances, rather than restricts, it. Sunglasses should therefore keep your vision clear and let enough light through so that you can see properly.

Which sunglasses lens tints are suitable for driving?

Some sunglasses are barely tinted at all, others block out almost all natural light, and most fall somewhere in between. To find a pair that are suitable for driving, you need to look at the small print. Legally, all sunglasses lenses must be graded from category 0 to category 4; the higher the grading, the less light they allow through.

Category 0 lenses aren’t going to help you much when driving in the daytime. They’re almost clear, and won’t filter out much sunlight at all.

Category 1 lenses are suitable in low sunlight. They transmit a fair bit of light (43-80%), so probably won’t stop you getting dazzled when it’s especially bright – but are still too dark to use for night driving.

Category 2 lenses are your best bet for driving in the daytime. They reduce glare, while still allowing plenty of light back to your eyes.

Category 3 lenses are pretty dark. You can use them in particularly bright weather, but they may affect your vision inside the car. Remember, you still need to see your controls.

Category 4 sunglasses are entirely unsuitable for driving. They should carry a label saying as much (it’s a legal requirement), as they only transmit 3-8% of light. They’re more likely to be something you’d wear on the ski slopes, rather than day-to-day.

Types of sunglasses lenses

dog wearing sunglasses

Not only do you need to consider the degree of tint, but you also need to look at the type of lens. Who knew there were so many things to think about?

Variable lenses

Photochromic lenses are those that change their tint density depending on the light they detect. In particularly bright conditions, they should get darker to compensate. However, some only work using UV light. This is filtered out by car windscreens, so the lenses aren’t able to work properly.

So if you’re after a pair of sunglasses with variable lenses for driving, check that they’re able to react to visible light too.

Fixed tint lenses

Most sunglasses you come across stay the same colour, regardless of the brightness they encounter. These are called fixed tint lenses, and so long as they fall within category 1-3 (and preferably category 2) on the lens tint scale, they are fine to drive with during the daytime.

Polarised lenses

Some fixed tint lenses are polarised, meaning they have a special filter on them that aims to dramatically reduce glare, particularly from light reflecting off puddles or snow. Some people don’t get on with them, but for many they’re an option worth considering to keep your eyes comfortable and your vision clear.

Graduated lenses

While some sunglasses lenses are tinted evenly, others fade from a darker tint at the top of the lens to a lighter tint at the bottom. Some drivers find this helpful, as the glasses filter the bright sunlight from outside the vehicle, but give you a good view of your controls within the car, where it’s naturally darker.

What style of sunglasses are best for driving?

sunglasses on display

The sunglasses market caters to a whole range of face sizes and shapes, personal preferences and style. Somewhere out there, there’s a pair (or probably 38,781,146 pairs) that will suit you. But for driving, there’s one extra style requirement you need to think about.

Peripheral vision is how you see things that aren’t in your direct line of sight. When you’re driving, it helps you to glimpse potential hazards out of the corner of your eye. So your optimum pair of sunny driving specs are ones that don’t obstruct your side view too much.

That’s partly why aviators became so popular with pilots back in the day. They have thin arms (the sunglasses, not necessarily the pilots), enabling a wide range of vision. Some other styles are less well suited to driving. But if you avoid really thick frames, you can’t go too far wrong.

Keep them clean

Cleaning your sunglasses regularly, and keeping them scratch-free will also help with tip-top vision. When you’re not wearing them, keep your specs in a protective case, and invest in some glasses cleaner, a good cloth or some glasses wipes to remove smudges.

Prescription sunglasses

If you usually wear prescription glasses on the roads, you’ve got two options when the sun makes it difficult to see. Your best bet is contacting your optician, who can give you proper guidance on which choice is best for you.

Clip-on lenses

Some glasses are compatible with clip-on tinted lenses. Since you can usually flip them up or off when the weather dulls, they’re a good option for driving, as there’s no break in clear vision. And bonus: they’re often usually cheaper than a pair of prescription sunglasses.

Prescription sunglasses

Alternatively, you can opt for a pair of prescription sunglasses. Visit your optician to see the range they offer, and keep in mind the style and tint advice above. It's recommended that you get your eyesight checked every two years as an adult — and remember that you'll have to replace your prescription sunglasses every time your prescription changes.

Other ways to reduce sun glare

Sunglasses aren’t the only form of defence against getting dazzled. Sun visors are there to block out some of the brightness too — and they don’t just protect you against the sun when it's straight ahead. Most detach at one end, so that you can swing it round against the front side windows if that’s where the light is coming from.

Reflections are another common cause of glare. And while there’s not a whole lot you can do about the sun bouncing off snow and puddles (apart from wearing your sunglasses of course), you can invest in a little spring cleaning to reduce reflections from your bonnet, windscreen or side mirrors.

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