Most of us, when we get into our 40s, need reading glasses. There comes a time when our arms are not long enough! Interestingly, by my late 50s, I was able to read clearly without my glasses. Although I wore "progressive lenses" with corrections for distance, the computer, and reading, I found it easier to take the glasses off when looking up items in the files. This resulted in some amusing incidents when I couldn't find my glasses and discovered them in one of the file drawers I'd been looking at! I strongly suspect that most higher-ranking officers, certainly those over age 40, needed glasses for reading.
I've read that General Meade was quite nearsighted and wore glasses, accounting for the "goggle eyed old snapping turtle" nickname. He refused to be photographed in glasses. I'm sure there were others.
I've just ordered a rather decent pair from an online retailer,here in the U.K (Ineedspeks,i apologise for the spelling),they will fit lenses,according to one's prescription,and charge a reasonable £30 with no p+p,apparently,they are based closely on a known period example and there is a choice of gold or grey finish,i thought it was about time i obtained a pair as i'm "short sighted" and squinting just gives me headaches a'plenty.