I don't see why the entire process couldn't be automated. A machine could ask me "which is better A or B or are they the same?"
There are other parts of the exam that are more related to eye health, but I don't see why they vision prescription process and the eye exam have to be combined. How many people that don't wear glasses ever get their eyes examined?
"Which is better?" is the subjectivity people are hoping can be eliminated, the patient's, not the examiner's. This is an interesting black-box problem, I suppose it's possible that with the examination of enough eyes a system could suggest corrections, but I am skeptical.
There are other parts of the exam that are more related to eye health, but I don't see why they vision prescription process and the eye exam have to be combined. How many people that don't wear glasses ever get their eyes examined?