[Robe]

Looks like her prescription hasn't changed in years, coke bottles then and now

[Boogieman]

It's not the thickness of the lens, because that would be the same no matter what. It's the type of lens that is what is different. Check out the left eye vs the right eye in the newer photos. The left eye has a prismatic fresnel lens, you can see a little light scattering from it. The right eye still has a regular prescription lens.

For reference, here is a good picture of fresnel projector lens that shows the same kind of light effect: