2024-06-25
Why This Question Matters More Than Most
Driving is probably the activity where you spend the most time in bright sunlight and where the consequences of poor vision are the most severe. Glare from oncoming traffic, low sun on a westbound highway, wet pavement reflecting headlights after rain: these are situations where the right sunglasses are a genuine safety tool. The wrong ones, or none at all, can leave you temporarily blinded at exactly the wrong moment.
But choosing driving sunglasses is more complicated than it seems because the inside of a car creates unique optical conditions that do not exist anywhere else. Your windshield, your dashboard displays, and the fact that you are sitting still while the world moves past you all interact with different lens technologies in ways that can help or hinder your vision.
Polarized Lenses: Mostly Excellent for Driving
Polarized lenses are widely considered the best option for driving, and in most situations, they are. Road glare, the blinding reflection of sun off pavement, other cars, and wet surfaces, is almost entirely horizontally polarized light. Polarized lenses filter out horizontal light waves specifically, which eliminates road glare while leaving the rest of the scene visible. The effect is dramatic. A wet highway that looks like a sheet of blinding white through regular sunglasses becomes a clearly visible road surface through polarized ones.
On a sunny Alberta highway, the difference is safety-critical. You can see road markings, spot the car ahead of you, and judge distance to the next exit without squinting through reflected glare. For straightforward daytime driving, polarized sunglasses are hard to beat.
The Dashboard Display Problem
Here is the catch. Many modern cars use LCD screens for dashboards, infotainment systems, and heads-up displays. LCD screens emit polarized light. When you look at a polarized screen through polarized sunglasses, the two polarization axes can interact in ways that make the screen appear dim, discoloured, or completely black depending on the angle.
If your car has a heads-up display (HUD) projected onto the windshield, polarized sunglasses can make it disappear entirely. Some drivers also notice that their instrument cluster or centre screen looks oddly dark or shows rainbow patterns through polarized lenses.
Before buying polarized driving sunglasses, test them in your car. Sit in the driver's seat with the engine running and look at every screen: instrument cluster, infotainment display, any HUD projection. Tilt your head slightly side to side. If everything remains readable, you are fine. If screens go dark or show interference patterns, you may need to consider non-polarized alternatives or a different polarization angle.
Photochromic Lenses: Great in Theory, Problematic in Cars
Photochromic lenses that darken in sunlight and lighten indoors seem like the perfect driving solution. Put them on when you get in the car and they automatically adjust to the brightness. The problem is that most photochromic lenses are activated by UV light, and modern windshields block the vast majority of UV light. So when you are sitting behind your windshield, your photochromic lenses barely darken at all.
You end up with lenses that are nearly clear while driving in bright sun, which defeats the purpose entirely. This catches a lot of people off guard because those same lenses work beautifully outdoors where UV is plentiful.
The Workaround
Some newer photochromic lens technologies are designed to react to visible light as well as UV, which means they do darken behind a windshield. These are specifically marketed as "driving" or "behind-the-windshield" photochromic lenses. They cost more than standard photochromic, but they actually work in the car. If photochromic is what you want for driving, ask specifically for a visible-light-activated version and verify that it darkens behind your windshield before committing.
The Best Tint Colours for Driving
Grey: The Default
Grey is the most common tint for driving sunglasses because it reduces brightness evenly without altering colours. Traffic lights look the right colour. Brake lights are clearly red. The car ahead of you is the colour it actually is. For driving, where colour accuracy matters for reading signs, signals, and road markings, grey is the safest choice.
Brown and Copper: Enhanced Contrast
Brown and copper tints reduce brightness while slightly enhancing contrast. Road surfaces and obstacles stand out a little more against the background. Some drivers prefer this, particularly on long highway drives where the monotony of grey pavement against grey sky can be fatiguing. The slight warmth of a brown tint makes the landscape feel more defined.
The trade-off is that brown tints alter colour perception slightly. Traffic signals and signs still look recognizable, but they are not perfectly colour-neutral the way they are through grey lenses.
Yellow and Amber: Low Light Only
Yellow-tinted driving glasses are sometimes marketed for night driving or fog. They do enhance contrast in flat, low-light conditions, and some drivers find them helpful for dusk driving or foggy mornings. But they do not reduce glare from oncoming headlights (that requires polarization, which does not help with headlight glare either since headlight light is not consistently polarized). And during the day, yellow lenses let in too much light to serve as proper sunglasses.
If you drive regularly at dusk or in fog, a lightly tinted amber pair can be a useful supplement to your regular driving sunglasses. They are not a replacement for them.
Lens Features That Matter for Driving
Anti-Reflective Coating on the Back Surface
This is an underrated feature. Light entering from behind you, through the rear window or from bright side windows, can bounce off the back surface of your sunglass lenses and create distracting ghost images. An anti-reflective coating on the inner lens surface eliminates this. Most premium sunglasses include it. Budget pairs often do not. For driving, it makes a noticeable difference, especially when the sun is low and behind you.
Gradient Tinting
Gradient lenses are darker at the top and lighter at the bottom. For driving, this means the bright sky and glare from the road surface get maximum tint, while the dashboard and instruments in your lower field of vision remain more visible through the lighter bottom section. This is a practical feature for driving, not just a fashion choice.
Prescription Driving Sunglasses
If you need corrective lenses for distance vision, prescription driving sunglasses are a safety essential. Squinting against the sun while wearing clear prescription glasses, or wearing sunglasses that do not correct your vision, both compromise your ability to drive safely.
For progressive lens wearers, driving sunglasses deserve some thought. The intermediate and reading zones of a progressive lens are in the lower portion, which is where you look at the dashboard and centre console. Make sure the progressive corridor in your driving sunglasses allows you to read your instrument cluster and GPS screen comfortably. A gradient tint pairs well with progressives since the lighter bottom section preserves the near-vision zone.
Our Recommendation
For most drivers, grey polarized lenses with a back-surface anti-reflective coating are the best all-around choice. Test them with your specific car's screens before buying. If you have a heads-up display that conflicts with polarization, switch to a grey tinted non-polarized lens. And if you want photochromic convenience, make sure you get a visible-light-activated version that actually works behind a windshield.
We fit a lot of driving sunglasses in our shop. Bring your prescription in and we will walk through the options that work with your vehicle and your vision needs.