If you are like me you got Transitions lenses for you presciption glasses last time you got a prescription glasses thinking this is great, no need to change glasses when going out in the sun, and they will change back to clear when you go inside automatically. You thought that you didn’t need to take the sunglasses with you everywhere you went. Before spending the extra money for this type of glasses I did the research. I thought I had everything covered with the research, but seems like I missed one major item. And I have been miserable ever since.
The way that Transitions glasses work is they will darken when you go outside and go back to clear when you come back inside. The way they do this is with the UV rays. When the UV rays are detected, they will darken. They reduce the glare and keep you from squinting outside in the bright sunlight. According to their website, it works with photochromic dyes which darken when exposed to ultraviolet rays from the sun. Once there are no ultraviolet rays from the sun they will clear up. So when you are out in the sun, they act like sunglasses, when you come back in a building they are like regular glasses. Since ultraviolet rays can damage your eyes, the glasses are blocking 100% of the rays, and in the long run will protect your eyes.
Now the problem comes when you are driving a vehicle or a passenger and it is very sunny outside.
From my research most factory windshields are built with a vinyl interlayer between the glasses that you really can’t see they are then fused together. According to the information I found at Carlite, who manufactures factory quality windshields for many vehicles, this layer is also a solar tint which absorbs Ultraviolet rays from entering the vehicle. This interlayer doesn’t darken the windshield that you can really notice, but instead by blocking the UV rays, which prevents the Transitions lenses from getting darker while in a vehicle. While you are in a vehicle, your glasses don’t get darker, and you are left squinting. Granted you are not being damaged by UV rays, but if you can’t see because of the sun you run the risk of getting in an accident.
To test this out, I took my glasses off (while the passenger) and held them out the window and they darkened, back in the car they became clear again. I did notice that on the windshield there is a little tag etched in the windshield that says UV. So it does tell you on the windshield that it will give you UV protection from the windshield.
I also emailed the people at Transitions.com who make these special lenses to ask about the way Transitions lenses perform inside the vehicle. They sent back a real nice email explaining about the UV protection built into the windshield that protects the inside of the cars from damage from the sun and the people in the car from harmful UV. And they did agree that the glasses will not darken due to this fact. They did also state that these glasses are not meant to replace sunglasses. The main objective of these glasses is light control. They also prevent 100% of UV protection.
If you are squinting while wearing Transitions lenses in the vehicle, it’s really not your imagination. These lenses will not darken inside a vehicle as they do outside. You may still need to wear sunglasses if you are bothered by the sun while driving.
Resouces:
http://us.transitions.com/healthysight/visionandglare.htm
http://www.carlite.com/whycarlite.html
