The Superfocus e-mail contained this:
We know that you will be eager to try your Superfocus glasses once the package arrives. However, we strongly encourage you to take your Superfocus glasses to a local optometrist/optician for proper fitting. You can use the Fitting Certificate that has been included with your Superfocus glasses and we will pay the optometrist/optician for the fitting, directly. A custom fitting is the best way to enjoy maximum comfort while minimizing the risk of Superfocus damage due to improper adjustment.
This was not mentioned in the detailed comments made recently here by "villager".
I'll probably ask my optometrist (probably an optician will actually do it). It's a bit awkward since I ordered the glasses directly from Superfocus. In the fall of 2011 I stopped by and asked the opticians whether Superfocus was supported and they had never heard of it. Neither had my ophthalmologist retina specialist who examined my eyes a couple of weeks ago but who does not provide prescriptions.