I would try a warm wet compress using saline to soften the crust, to see if it can be removed. The apply some Terramycin or Neosporin to keep it from drying.
Here are some examples with pictures of pecked heads and healed injuries:
https://www.backyardchickens.com/threads/whole-top-of-pullet’s-head-been-lifted-off-by-bully-chicken-what-do-i-do.1584007/...
Yes, other chickens will do this, especially to a new one. It can take weeks to heal the skin, keeping it moist with ointment to not let the tissue dry out.
Are the OEG’s in with other chickens or alone in a coop/run? Could she have been wounded by another chicken? Or could a raccoon have grabbed her through fencing? I would flush the eye twice a day, and use either Terramycin ointment (from a feed store) or Neopsorin ointment on it 2-3 times a day...