it can naturally heal/calm down on its own but a cream like Terramycin or neosporin (its cheaper and more easily found) can help it from getting an infection. If there is discharge or if it gets cut from her scratching her eye then I'd definitely put the cream on her. You can purchase either from amazon or a local walmart or pharmacy.If your chicken has bubbles in either eye your likely dealing with MG. MG can be caught by basically anything, wild birds can pass it and then your chickens will pass it quickly. If there aren't any bubbles then you fine, probably just a sting or someone pecked at her eye. Good luck!