The majority of customers interested in purchasing photochromic eyewear usually have valid concerns regarding the darkening performance of the lenses. These are especially important for individuals wearing prescription photochromic eyewear.

Thoroughly addressing these concerns depends on the type of glasses and the environmental conditions. However, understanding some basics regarding photochromic eyewear will provide a solid start for making the best choice.

  1. How do photochromic lenses work?

Photochromic compounds are built into the lens, and the sun’s UV rays trigger the compounds to darken. Away from sunlight, lenses reverse back to a clear state through a thermal process. Beyond this basic process, environmental conditions can significantly impact the performance of photochromic eyewear.

  1. How well do photochromic lenses work in cold weather?

They actually get their darkest in cold weather, which makes them more suitable for snow skiers than beachgoers. However, once inside and away from the triggering UV light, cold lenses take longer to regain their clear color than warm lenses.

Photochromic Performance In Heat

High temperatures don’t allow photochromic lenses to get as dark as they normally would.

  1. How well do photochromic lenses work in hot weather?

The higher the temperature, the less dark photochromic lenses will be. This thermal effect is called “temperature dependency” and prevents photochromic lenses from achieving true sunglass darkness in very hot weather. If you’ll spend a lot of time in extremely hot and bright conditions, such as the desert or a tropical beach, photochromic lenses will probably not perform to your satisfaction. For these conditions, consider purchasing prescription sunglasses or traditional sunglasses instead.

  1. How well do photochromic lenses work for driving?

Most windshields have UV protection built in, which significantly reduces the amount of UV light reaching lenses. This prevents the photochromic compound from working to its fullest, so lenses will darken considerably less in a car with built-in UV protection.

Clear Photochromic

Lenses that have a clear, neutral state will never get as dark as those that start out darker.

  1. What should I look for if I want the darkest photochromic lenses possible?

Lenses that have a clear, neutral state will never get as dark as those that start out darker. For darker lenses, try starting with a lens that is already at least slightly shaded. Look for glasses with lenses that are medium or light gray in their neutral state since their transition in the sun will be closer to a sunglass feel than lenses that start as clear.

Understanding the basics of photochromic eyewear hopefully helps individuals considering purchasing them make the choice that is right for them and the conditions they most frequently find themselves in. Fortunately, there’s likely a solid solution for every situation, so be sure to make sure all questions are completely addressed by an eyecare professional.