t0ny:

 

So OPSM told me that they do a PD check when you buy the glasses from them. A standard eye test which they give prescription for does not include a PD check. This all sounds too dodgy and iam surprised no one has investigated this practice

 

That's completely logical reasoning, and I'm not sure what there actually is to investigate.

There is no reason to do measure PD for a standard eye check as it's nothing to do with eye health and only necessary when you're actually fitting glasses. 

Yes PD is essential for a correct prescription, but most glasses sites have their own methods and the numerous apps out there to measure PD are essentially doing the exact same thing as the tablet apps now commonly used by optometrists.