The original intention was to have one vertically and one horizontally mounted barbers pole in the pilot’s peripheral vision to provide guidance during approach and landing. This configuration was not very effective, I'm not sure if any aircraft actually used it in service.
AFAIK, there was only one civil aircraft that had this capability, and in fact only one particular model...the Grumman Gulfstream One, and that aircraft was owned by the US television and radio personality, Arthur Godfrey.
This aircraft was FAA approved, at the time, for CATIII hand flown approaches.
PVD...very effective, if used properly.