medical eyepatch

An eyepatch worn for medical purposes. It may be held by an elastic strap or an adhesive strip.

In Japan, these are typically square-shaped and white (Danbooru post #1272300).
They might also include holes for ventilation (Danbooru post #129447).

If a character's eye is covered by bandages, use bandage over one eye instead.

This tag implicates eyepatch (learn more).