My Elderly Mother (age 93) Has Had A Serious Eye

My elderly mother (age 93) has had a serious eye infection for almost a year. She has a VERY dry eye and has seen several eye doctors (optometrists and ophthalmologists) and has been treated with ointments, drops, oral antibiotics, etc. Since mid-February she has been on vancomycin drops every two hours. Last week her dr could see that the infection is still present and put her on an additional drop - Gatifloxacin. Can you tell me anything about these meds and if there is something else we should be doing?