Why do pirates wear an eye patch?

Some assume pirates wore eye patches to cover a missing eye or an eye that was wounded in battle, but in fact, an eye patch was more likely to be used to condition the eye so the pirate could fight in the dark. read more

Pirates frequently had to move above and below decks, from daylight to near darkness, and Sheedy says the smart ones "wore a patch over one eye to keep it dark-adapted outside." When the pirate went below decks, he could switch the patch to the outdoor eye and see in the darkness easily (potentially to fight while boarding and plundering another vessel). read more