Firstly, what is the PD? It’s not such a silly question; we know the acronym represents ‘pupillary distance’ or ‘inter-pupillary distance’ but in what context? It could be a simple distance PD or a near PD; it may of course be a monocular PD that is required, or maybe one taken in the spectacle plane rather than on the face, if the vertex distance is particularly large. The vertical position of the optical centre is vital when dealing with many prescriptions and lens forms, and so it continues.
When asked for a PD, a reasonable reply could be: “Which one?” The law is very clear as to what information needs to be recorded on a prescription and, at present, it does not include a PD. We have long argued that the PD (whichever form of that measurement is required) is a dispensing function and not part of the refraction result. It is true that some optometrists measure a rough PD to position the trial frame or phoropter in front of the patient’s eyes. Such information is rarely, if ever, recorded on the patient record as it has limited clinical significance in that situation.
So, a patient requesting their PD of you, a dispensing optician, will have no concept of what they are asking for. Likewise, they will not realise that giving their PD to an internet supplier would not automatically mean that their spectacles will be centred correctly. When asked for a PD it is quite normal to feel insulted (“What a cheek!” may go through your head). It is always good advice when met with unintentional (or intentional) rudeness to keep calm and reply with great courtesy. If the patient is new to your practice, you may say with confidence that you do not have that information to give them. It is slightly more complicated if it is an existing patient whose measurements you would have on file. If you refuse to give the information, the patient may insist on their right to see their records and obtain the information that way. You may then, as politely as possible, reply that the information you hold is out of date and not compatible with their latest spectacle prescription, for the complex reasons given above. Many will not believe you and still demand their rights; you cannot reasonably refuse them copies of their records within a time frame and cost laid down in the law.
Of course, you may choose to give the PD on request, for goodwill or simply for a quiet life. It is then recommended that the information is issued in writing on the form found in the Advice & Guidelines section of the ABDO website. It protects you from claims that wrong information was issued deliberately. Of course, you must be sure of the accuracy of the measurement issued; if it is incorrect and spectacles are made up with that error, you would be liable in a court of law for damages.
The choice is yours; I would suggest you judge each situation on its merits. There will be occasions when you wish to be helpful and others when the request really sticks in the craw and you want to refuse, always politely, but in the full possession of the facts and the consequences of your actions.