What does "axis" mean, in eyeglass prescriptions?

Answer 1

"imaginary line in an eyeglass lens that passes through the optical centers of both surfaces."

In other words, you have astigmatism. If you didn't have astigmatism, the axis would not be on the Rx.

Remember protractors? The degrees go from 0 to 180. Same principle. The axis designation is where you see the clearest when you have an astigmatism.

Answer 2

1