Eye Patch (3.5e Equipment)
From D&D Wiki
A mundane piece of cloth, worn over the eye. It can be used to cover a missing or curious looking eye. When wearing an eye patch over your dominant eye (the same side as your dominant hand, if you have no preference, assume the character is right handed), the character takes a -2 on spot checks, and -1 on all ranged attacks.
Variant rule: Light sensitivity
Eye patches can be used, by people with two working eyes, as a means of preserving vision.
After the patch has been worn for twenty four hours, if the user is in shadowy illumination, the character can move the eye patch from one eye to the other, using a standard action. Doing this allows the character to see as though he were in bright lighting, to represent his night adjusted eye. However, if the character, while using this ability, is exposed to bright light, he will suffer day blindness, as though he were drow. This effect can be canceled simply by switching eyes again. Removing they eye patch ends the effect completely.
This wouldn't have ever made it into documentation had it not been for a ranger in our party, who took the habit of wearing an eye patch, not because he had a missing eye, but because he liked it. It was also his character that created the variant rule, after a brief experiment of our own.