I wouldn't bother with the antibiotics unless you see symptoms. Doxycycline ,erythromycin , gentamicin , cephalexin . Sometimes they will get a hard disc of solid puss cover the eye like a shield . You have to pinch it out , like you would a contact lense. Unfortunately once the eye gets infected and balloons out cutting across the eyelid and scraping the cheese out is the only option.
This might just have been triggered by a foreign body in the eye or a peck. Even sinusitis has similar symptoms .So hopefully it was exclusive to her and your other birds won't be in any danger.
Be sure to disinfect her quarantine area.
Thanks. She had no puss in the eye at all. It was just shut. so perhaps you are right that she had either sinus or a scratch.