Do photochromatic glasses cause any harm to the eyes?

Question

Do they block UV radiation? Are photochromatic glasses better than UV coated sunglasses?

Answer 1

Some of the above information is incorrect.

They don't have to be in the darkened state to give the UV protection, it is always there. So the time it takes them to darken doesn't matter, the UV protection is there anyway...the UV protection has nothing to do with the color. They give 100% UV protection at all times.

I think he must have lenses that are a few years old, because the last generation of Transitions gets very dark outside.

Indoors they take a few minutes to get completely clear, that is true , but it is no worse than walking into a building with your Rx sunglasses on, then having to switch glasses to clear ones.

The only disadvantage of Transitions, is that they won't change inside a car. The windshield blocks the UV rays that activate them.

Transitions, ( photochromics) were never designed for, nor advertised as a replacement for a real sunglass.

They give good protection if you don't have a sunglass , but they don't really replace it.

Answer 2

Transitions lenses that are plastic do have uv filters in them already. Glass photochromic lenses do not have uv  protection until they are darkend and the silver hallide chrystals have turned ont heir side. Even then they do not block as much as the Transitions lenses do. The Glass ones will turn dark a bit under the windsheild, but they are heavy and really uncomfortable for most people. Phto chromics usually do not cause nayone any harm. I have seen some incidents of chilren being put in them too early in life and causeing some photophobia becuase their eyes never had to learn to get used to light on their own, but after not wearing them for a few days they went back to normal light sensitivities.  In 27 years I have only seen this twice. Just some FYI.