On 09:05 11 May 2021, jon said:

I have surveyed several on line suppliers of prescription spectacles
and found that most seem to use a similar web page arrangement and
source the ordered item from the US, although through a UK office.
This web page ordering system is very simple and is heavily biased
to making a sale at all costs. The short comings are that they only
have a certain number of frame fitting sizes and in order to get
exactly what I want is impossible.

I ordered some £30 prescription rimless reading glasses which were
quite well made, but because I could not get a 16mm nose bridge my
eye pupils were not in the centre of the 50mm wide lenses.

The pupil distance of the final specs should not be affected by the
width of the bridge.

Unless the position of each pupil was positioned within each lens but
that's a strange way of doing it. Normally you measure the pupil to
pupil distance and ask the specs are made up to suit that.