'Blind' characters should have whitened eyes on their portrait. Like, not all-white, but just a medium-grey pupil with a light-grey iris, or something.
There is also the case of people getting blind from a bad wound, sickness, old age, ...
The cause of the blindness determines a lot of its consequences on the organism and on the skills of the character affected, so I guess it would be a bit tedious to list all the possible causes, don't you think?
And what about one-eyed characters? And the squinting ones ?
