You look at a little house in a field. Then you look at a spot and they blow air into your eye.
Nothing much to it.
You look at a row of letters with each eye and then you look at them again through a bunch of different lenses.
Finally you get drops in the eyes and after a while get another examination..
If you are lucky and your eyes have changed you get to pick some new frames and lenses to look through.
I actually got an added benefit - genuine Polaroid to cover my eyes when I walked outside because my eyes were dilated from the drops and the glare can be pretty intense.
Not bad for about an hours time.