Our Martha had that. She ultimately lost use of her right eye, and the right side of her face never fully recovered. I mean, it's not still red or yucky or anything, but it turned white where the pox fell off & it left her blind on that side. It has been 2 months since she got over the fowl pox, but the eye is permanently damaged. She has always been a sickly chicken, though. I doubt she'll ever lay. She's been here almost 6 months and was about 6 weeks old when we got her, but she's not any bigger or more developed than my 13-week-old mutt pullet. We really need to cull her, but she's DH's baby & he doesn't have the heart to do it. We agreed when we got chooks that he would do the culling as he has done it before, no big deal.... except that when he was a kid and had chickens, they weren't pets & didn't have names. He can't bring himself to give Martha The Mole the serious neck-pulling she needs.
But, as long as she's eating and drinking and pooping and foraging for bugs and stealing treats from our hands, I guess we'll just keep her.