Eyepatch

An eyepatch (or eye patch) waa a device worn over the eye, generally used to protect an eye that was injured or missing.

In an alternate timeline where Britain was a fascist republic state, that timeline's version of Alastair Lethbridge-Stewart wore an eye patch. (TV: Inferno)

Amy Pond likened the Eye Drive worn by Madame Kovarian to an eyepatch. (TV: The Almost People)

Behind the scenes
Nicholas Courtney frequently retold an anecdote from the filming of Inferno at fan conventions. For the serial's reveal of the alternate Brigadier, he began with his back facing the camera and then spun around in the office's swivel chair. When Courtney spun the chair around, the entire cast and crew had also put on eyepatches but he managed to continue as if nothing had happened. "Everybody was wearing an eyepatch" became closely associated with Courtney, and was among the tributes to him written into The Wedding of River Song after he passed away in 2011.