I hear a lot of talk about Rx calculator's for wrap frames, but not much about verifying PD. The common practice of verifying a PD is to take a ruler and measure the distance from the front of the frame. After tracing these frames we have found that the frame PD comes out narrow, so we will take a frame PD prior to blocking and inset the lens more depending on the difference. The PD then verifies correct.

I am questioning whether this is correct and how does it affect the patient? If you take a PD from the minus side you will get a narrower reading. By doing what we are doing is this creating too narrow of a PD for the patient? So, what is correct? Am I hallucinating here or is this a valid point?

Bob