If you’re a thrifty sort, you’re going to love their two-in-one benefits: they look like regular clear lenses fitted on regular eyeglasses while you’re indoors but automatically darken when you step outdoors into the sunlight. Magic you think? Not so! Clever engineering no doubt. The ultraviolet (UV) rays from the sun affect the molecules in photochromic lenses, making them change color, making them darken even on overcast days when you step out because as we know, UV rays can penetrate clouds. Thanks to these nifty photochromic lenses, your eyes will always be protected from harmful UV rays.What’s more, photochromic lenses provide you with the best possible vision in all lighting through different shades of tint, without you even realizing that you need it. Also known as ‘transition lenses’, ‘adaptive lenses’ or ‘auto-tinted lenses’ photochromic lenses serve multiple purposes. Not to be confused with polarized glasses (sunglasses) that only provide superior glare protection, especially on the water, that block intense reflected light outdoors. These only have a set tint that isn’t changeable and don’t adapt to light the same way photochromic lenses do.

How Do Photochromic Lenses Work?

You might be wondering why would you need these when you have a perfectly good pair of sunglasses. Regular sunglasses block specific wavelengths of light with either colored filters or via polarization. However, since photochromic lenses are carbon-based, the molecules react to UV rays to become darker. The more intense the UV rays, the darker the lenses get. So, they adapt from clear (while indoors) to different shades of dark depending on the levels of UV light. It can take up to 30 seconds for the tint to darken on photochromic lenses and between two to five minutes to return to normal when you go back indoors.

Usually made from either plastic, glass or polycarbonate, photochromic lenses are available as different prescription glasses for people who wear corrective prescription eyeglasses. Plastic photochromic lenses are usually favored over glass because of their molecular structure because the tint on plastic lenses tends to be more evenly distributed than on photochromic glass lenses. Invented in the 60s, photochromic lenses didn’t gain popularity until the 70s, but they are all the rage today, thanks to their ability to double up as eyeglasses and sunglasses.

Who Needs Photochromic Glasses?

Since they can be worn all day, every day, like regular glasses, anyone who wears glasses for vision correction would benefit, but especially those who regularly move from indoors to outdoors. Particularly good for children who are unlikely to be able to handle two separate pairs of glasses, and definitely need a pair of sunglasses given how much time they spend outdoors playing.

So, Are Photo Chromatic Glasses Right For You?

Here are some facts to help you make up your mind.