There is a lot of confusion and conflicting information regarding Serengeti's famous photochromic lenses and whether or not they darken behind a windshield.
Serengeti lenses are right at home on the road, which they were designed for. Their flagship lens is even called the Drivers lens. Their marketing is heavily geared toward driving and similar conditions. From my own experience and the experiences of all the happy customers Serengeti has sold lenses to since 1985, the product really does live up to the marketing.
You would think then, that the photochromic lenses would darken and brighten based on the conditions while behind a windshield. But it isn't so simple.
Despite having some patents that imply the photosensitivity of the lenses may not only rely on UV light exposure to work, Serengeti has confirmed that their lenses do work with UV rays alone:
"As the pioneer of Photochromic technology, Serengeti® leads the industry in creating lenses that adapt to any light condition in any setting. Serengeti® Photochromic lenses are activated by the amount of UV radiation in the atmosphere and engineered to transition from light to dark, gradually.
In bright conditions, UV radiation is more intense. The lens molecules expand in size, darkening the lenses. Less light can then pass through.
In darker conditions, UV radiation is less intense. The molecules shrink and separate, lightening the lenses. More light can pass through.
Your eyes are always protected and receive the optimal amount of light needed at any times and in all weather conditions.
You are able to discern shapes and colors more quickly while eliminating eyestrain."
Modern cars have had windshields that are 100% UV protective for several decades. The development of UV-protective glass for windshields began in earnest in the 1980s and 1990s as awareness of the harmful effects of UV radiation grew. By the early 2000s, most new cars were equipped with windshields that provided nearly 100% protection against UVB rays and a significant amount of UVA rays. Today, it is standard for windshields in almost all vehicles to offer complete UV protection. This is achieved through the use of laminated glass that has a plastic layer (usually polyvinyl butyral, or PVB) sandwiched between two layers of glass, which effectively blocks UV radiation. Keep in mind that the Drivers lenses were introduced in the 80s.
(It's interesting to note that Transitions Drivewear does darken behind a windshield and does not rely on UV rays to do so).
So do Serengeti lenses change behind a car windshield or not?
SportRX has put out several videos over the years that explicitly say that Serengeti lenses do darken in cars.
In this video at the 5:55 mark, Rob says exactly that.
Now I know that Rob Tavakoli knows a lot more about sunglasses than I do, but I needed more confirmation.
I reached out to Serengeti and this is what they sent me:
"Indeed, the lens reacts to the amount of UV radiation in the atmosphere, engineering to transition from light to dark gradually. Depending on how much light is being transmitted through your windshield you will notice a gradual change."
I pushed them to be specific:
"Can you please clarify? If the windshield is 100% UV protective will the lens not adjust at all or will it still adjust based on some other factors like visible light exposure?"
And this is what they replied:
I also found an old SportRX chat I had in which I asked the same question:
So there is a bit of confusion regarding what happens to the lenses.
In my experience of wearing all of Serengeti's lenses for years, in all conditions and seasons, I am sure they get darker in a car, but only partially.
Firstly, it is important to note that Serengeti lenses are only moderately photochromic. Even in the darkest room, they are still dark category 2 lenses with a full tint. In full sun, they do darken, but it is hard to notice the difference visually. It is noticeable how the slightly darker tint is more comfortable to look through in full sun, but the change is not easily apparent to the eye.
Secondly, though windshields nowadays block nearly 100% UV light, passenger windows do not (which is also important to know for skin protection if the sun is shining from the side on a long drive). I think the UV light that comes in through the side and rear windows changes the tint somewhat and that could be why there is some conflicting information.
That is also why regular transition lenses that change from fully clear to fully dark will still get somewhat of a tint when in a car, but not a full tint. For Serengeti, that slight change is enough to add comfort to the tint in full sun.
This is what I've concluded driving in overcast conditions and full sun. I am convinced the lenses get slightly darker when it's sunny outside.
Another factor that should be considered is the necessity of having a very dark tint when under a shaded roof. Since, for most of the day, the roof of the car shields the driver from direct sunlight even more than a hat does, there is less need for a very dark tint. For most people, a 15-18% VLT is probably the sweet spot while driving. Since Serengeti Drivers are a 23% to 9% VLT, even having a slight darkening effect in full sun gets the lenses right where they need to be. When the driver leaves the car and the protection of the roof, the lenses can then adjust to add even more protection and comfort.
In conclusion, while Serengeti’s photochromic lenses might not fully darken behind a modern UV-protective windshield, they still offer exceptional comfort and clarity. The slight darkening that does occur, combined with their overall quality, makes them an excellent choice for driving and other activities. I highly recommend Serengeti lenses for anyone seeking reliable and comfortable eyewear on the road.
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