I used one medically, they were an option on early Zeiss retina cameras. But over the years they mostly were put in storage. Zeiss hasn't made the fundus camera it goes with since 1995. They were mostly used on the 1960's version of the camera. Later photographers realized that motor drives really made life easier. So the camera is probably 1960s vintage. May need some work if it has been sitting in storage.
I too looked at one to replace a IIIc I had with a 25 f4 Nikkor. Made some offers to the hospitals I knew had them but they wouldn't sell to a private party at that time. There was a comparible Zeiss Contax without a rangefinder. The IIIc with the 25 went everywhere with me, would have liked to upgrade it.