I've done searches on Google with terms like "healing time for face wounds," and read the Wikipedia pages on "wound healing" and "facial trauma." I didn't find anything about how long it might take to heal.
The idea I'm going for is that someone took a knife to my character's face (male, if that makes any difference, which I don't believe it should). The cut runs from the side of the forehead, over the left eye, and down diagonally over the lips.
I'm not very clear on exactly what the effects would be. First of all, I know there is obviously not a lot of skin between the knife and the bones of the face, so would there be damage caused to the bones beneath? Also, I imagine he would lose the eye, and so then I wonder if the scar formed across the face would shut the eyelid permanently if it was closed during the healing process. A third problem I have is how it would affect the muscles of the face. Would he lose the use of the muscles of his face if they were damaged by the wound?
Most importantly, though, is how long it would take to heal. I have no sense of perspective on how long wounds like that take to heal. Any help would be hugely appreciated!
ETA: As far as the nature of the wound, it would have been inflicted by someone deliberately intending to badly wound him, and probably holding him down (the details are somewhat up in the air at this point). So it ought to be a pretty deep wound, including cutting the eye, which is why I'm curious about how severe the effects of something like that are.