New materials and chemistry involved inside the most recent generations of the lenses have created significant progress in addressing the 2 fundamental standards for choice :
Older generations (and a few existing generations) retain a yellow or somewhat jaundiced hue even when not exposed to extremely violet light (indoors by way of example). The most recent generation Transitions are broadly regarded to become the most effective available and almost completely obvious within the absence of extremely violet.
Most more recent photochromatic lenses make a fast transition from mild to darkish as they are exposed to extremely violet - the real check and the differentiation may be the price at which they regress in the darkest tint to very clear. Again Transitions lenses are extensively thought to be greatest in school in this regard.
Transitions lenses are a broadly held trademark for any distinct (latest) generation of components and technologies which might be combined and sold beneath the "Transitions" brand name. Other (but comparable) names aren't the identical, and are typically regarded to be not as very good, as they are from more mature technology photochromatic technology.
Finally - never count on your photochromatic lenses (regardless of which manufacturer or technology) to make considerably of the distinction while driving, because the windscreen of the vehicle is made to absorb most of the UV ahead of it enters the cabin - hence the lenses in your eyeglasses have nothing at all to react with. In the event you require or would really like tinted lenses while driving, you are far better off getting two pairs on the identical body with prescription very clear and prescription tinted lenses.