[Magdalen] Specs advice?

[Roger Stokes]

On 27/05/2018 03:35, Ann Markle wrote:
> You do need a measurement of pupillary
> distance, which was available from the last time I purchased glasses from
> an optometrist/optician practice. That measurement doesn’t change much,
> even with significant weight loss or gain.

That constancy is one of the reasons it is used in face recognition such 
as at border control. The apparent distance can vary as a result of 
spectacle lenses refracting the light which is why it's "no glasses" 
when doing that check.

Roger