Alternate theory

so they didn't stitch up the wound? I don't think a patch would help if they aren't even closing the wound.

Patches are easier to look at than the scarred hole where an eye used to be

so eye patches are for vanity?

If they actually lost an eye, yeah. Otherwise, sailors and pirates did use them to make sure one eye was always adjusted to the dark.

Why was it only sailors or pirates losing eyes, why were they so prone to eye related hazards?

Splinters from cannonball impacts mostly

so they didn't have wood or cannons on land?

On land they had stone fortifications, whose shrapnel would be more likely to kill you.

cannons weren't used on battlefields? Battlefields normally covered in trees because large scale tree felling for agriculture wasn't yet mechanized so clearing areas not immediately used for farming would be redundant?