Some pirates wear eye patches. Right? It's because something must have happened to that eye, and they're just covering it up. Plus it also makes them look a tad more badass than usual. But as it turns out, that's not the actual reason.

Of course, not all pirates wear them eye patches.

But they aren't doing it for the reasons you think they are.

Those eyepatches were worn to keep one eye adapted to the dark so when they went under deck, they could switch the patch to the other eye and see right away.

Sounds like a genius hack to me!

And so they did have two eyes.