I found my hen with a bubble like substance in her eye. They are itchy and she has been rubbing them. I started all of them on Dimethox. Not sure if its the right treatment. But its better then nothing.
She has a lot of eye drainage with it too I see. Have you had any respiratory disease in the past with your flock? Di-methox works well on coryza. Does she have a bad odor about her head? Coryza typically does. MycoplasmaG. is another disease they can get, and sometimes they can have both at the same time. For mycoplasma G. Tylan 50 by mouth or by injection 1/2 to 1 ml for 3 to 5 days is good. Here is info on the different resp. diseases: http://edis.ifas.ufl.edu/ps044
I would probably just put some neosporin or triple antibiotic ointment in her eye. Gentamycin is for gram negative bacteria, and I'm not a vet so I wouldn't tell you to use them. Someone else may know, but you don't know for sure what you are dealing with yet.
I did not notice a smell. I do have LA 200. Would that work? Or should I just get the tylan. I do have terramycin for eyes. About 5 years ago I had an old english game bantam that had the same thing. She died. No other birds got infected and I never found out what it was. And didnt know what to treat it with. So I never treated it. She ended up growing tumors or something out of her eye and inside her beak. Was like a soft cheesy tumor.
LA200 will treat CRD (also called mycoplasma or MG.) Tylan is usually the first drug listed for treatment of any respiratory disease when it is unknown. The soft cheesy tumor that grew out of your chicken's eye and beak could have been pus that hardened. It is really important to know what you are dealing with, so think about getting a necropsy of one of your birds by the state vet or at least tested by your county extension agent. Here is a thread on LA200: https://www.backyardchickens.com/t/631458/miracle-la-200-dosage-and-vetrx-for-crd-treatment
I would use the LA200 if I thought it was mycoplasma gallisepticum, or I would use the sulfadimethoxine (Di-methox) if I thought it was coryza. I'm not sure that I would use both at the same time. In the link in post # 4 It gives recommendations on drugs for the various diseases. Someone else with more experience may disagree with me.