Sorry for the confusion, Snake is the name of my chinchilla.
I caused the receptionist at the vets to run and hide because she actually thought I had a snake... you'd think she'd wouldn't be scared being a receptionist at the vets...
They're being treated with 'Fucithalmic' which is an antibiotic eye drop. We were 99% certain Snake's eye infection was due to a foreign body and not contagious. None of the others caught it. It was only after she was fully recovered that Cheech got the infection weeks after.
A little update: I found Cheech with her head and eyes in the area where they all pee. Basically they pee from one of the top levels and she was underneath that with her head in the corner, I don't know why. I'm going to clean the area and secure some wood there so they can't pee in it. I think perhaps the two eye infections are unrelated, but still any suggestions would be very much appreciated.