The Colonel's body, with the mind of the Prisoner, takes out a pair of National Health spectacles from the breast pocket of his jacket. He attaches two different coloured eye pieces over the lenses so to read the message created by a number of slides. This to discover the whereabouts of Professor Seltzman.
Well that is all well and good, and in the past there has been some discussion on whether or not the Prisoner's voice would be the same, seeing as his handwiting remains the same. So where's the question here? Well I don't recall the Prisoner-No.6 actually wearing glasses in the Village. The only time he does, is when he is pretending to be a doctor in 'Dance of the Deda,' when he finds a pair of spectacles in the breast pocket of a white coat. So I can only assume that the Colonel wear spectacles, and those seen worn belong to the Colonel. But if the Prisoner's handwriting is the same, would the Prisoner-No.6's mind really need spectacles when he doesn't wear them in the Village? I suppose that would all depend on how well the Prisoner-No.6 sees through the eyes of the Colonel!
Footnote: In reality I can only assume that the spectacles worn by Nigel Stock are his own, and not those of Patrick McGoohan, as we see him wearing his own spectacles in 'Dance of the Dead.'
Be seeing you