Photochromic: One Word, Many Technologies

If you think you know what photochromic lenses are, think again. Chances are, there’s more to them than you realize.

The word photochromic comes from Greek—photo meaning light, and chroma meaning color. So, photochromic quite literally means something that changes color with light. But light is a complex subject, and because of that, not all photochromic lenses work the same way.

The Classic Photochromic Lens

The most common type of photochromic lenses uses molecules and pigments that react to UV light. Step outdoors, and within 10 to 20 seconds, they darken through a chemical reaction. It’s a clever solution—but not without its limitations.

For starters, the transition back to clear can take time—anywhere from 2 to 3 minutes, depending on the lens. They’re also temperature-sensitive: colder weather slows them down and can cause the lenses to stay dark longer than needed.

Another downside? They don’t work inside cars. Windshields block UV rays, so the lenses don’t get the signal to darken. Since UV light is invisible to the human eye, the lenses might appear dark even when you’d prefer them clear. Still, this technology offers a good level of light adaptation at a fairly accessible price.

Over time, manufacturers have introduced new types of photochromic lenses to tackle these issues. Some lenses now offer limited activation behind windshields, though they still don’t get dark enough and remain slow to react.

Eventually, companies decided to take a completely different approach—and that’s when electrochromic lenses entered the scene. These lenses incorporate an electronic system. When an electrical impulse is applied, the lenses darken—much like the windows on airplanes.

This innovation brought some improvements: faster transitions, but not instant. And because of the high energy requirements, they need batteries—adding weight, bulk, and the hassle of recharging. While that might be acceptable in stationary environments, it’s not ideal for portable gear like sunglasses or ski goggles. Unsurprisingly, electrochromic technology never really took off in the outdoor sports world.

The New Generation: IRID® Lenses

A much more recent advancement has emerged in the form of IRID® lenses—electronic photochromic lenses that solve many of the issues faced by earlier technologies.

These lenses darken in less than one second without the need for batteries, thanks to a built-in solar panel. The panel senses the intensity of visible light—not UV—and powers a liquid crystal film that adjusts the lens tint in real time.

IRID® lenses go from nearly clear (Category 1) to dark sun protection (Category 3), smoothly covering all the shades in between. Since they operate on visible light, they react to the light you actually see. They’re also not affected by temperature changes, making them a reliable choice in any environment.

This is the same type of fast-reacting liquid crystal technology used in high-performance welding masks—now adapted for sports and outdoor use.

There may be no such thing as the “perfect” lens—but the right lens does exist for your specific needs, sport, and budget.

We hope this breakdown has helped you better understand the wide variety of photochromic lens technologies out there. So next time someone says “photochromic lenses,” you’ll know there’s a lot more than just one kind.