What index of plastic would be good for the lenses of my gles?

i think it depends which frame you are going for, if you are going for a rimless i would go thinner than a 1.6, I don't agree with the other person that answered.. however if you are going for a thick rimmed plastic frame a 1.57 would be fine, because the frame ( if glazed correctly.i.e all the thickness at the back) would hide the lens quite well.