Are those scabs around her face on the left side? It could be that she possibly has some fowl pox that have affected her eye. Fowl pox can create a right environment for secondary infection. Mucus, foam, or pus in the eye with swelling can be mycoplasma gallisepticum (MG,) a respiratory disease that is common around some backyard flocks. Tylosin powder in the water or Tylan injectable can help treat symptoms. You can get tylosin powder for pigeons online, but Tylan injectable may be harder to find in feed stores. Your local vet may be helpful.
MG is a chronic disease that may come and go. Most people close their flocks with MG. It can be transmitted vertically through hatching eggs.
