Fowl pox can cause a scab like that, and eye infections can be common afterward. There is no treatment for fowl pox which lasts 2-3 weeks, but an eye infection should be treated with Terramycin or other antibiotic eye ointment or drops, Vetericyn, etc. Many chickens lose sight in an eye after an eye infection, so treatment is important. Let us know how she is getting along in a couple of days.
