Chatfield's Sketch of Henry Wirz, Andersonville Commandant

Captain Henry Wirz, Andersonville commandant
What was it about Wirz's left eye that intruded upon Edward's consciousness 51 years after having endured the trauma of Andersonville?

This hand-sketch of Captain Wirz (with eye emphasis) was found buried within the pages of Chatfield's personal copy of Norman P. Chipman's 1911 book, The Tragedy of Andersonville