If you put terramycin on the eyes and it's the right medicine, it'll help. If you put it on and its the wrong medicine, it in itself won't do very much, but the condition will get worse. You could try Gentamicin eye drops. Just make sure that it does not have steroids in it. I suggested Neo-Poly-Dex, which is a good drop for conjunctivitis....only if there are no ulcers or scratches. Neo-Poly-Dex is neomycin and polymyxin B- two good broad spectrum antibiotics, and dexamethasone, which is a steroid.
If you can't truly can't afford a vet, I would try some kind of antibiotic drop or ointment. I prefer drops to ointment, but ointment works, too. Terramycin or Gentamicin won't hurt anything- and chances are will clear up the problem if there are no ulcers. Personally I would choose terramycin ointment. It's a very old drug, but it's usually a very effective one.
There is also tobramycin, which is probably the broadest spectrum. I don't know how you'd get that without going to a vet. If I had to choose between everything, I would get tobramycin. It's very broad-spectrum and also is effective against Gentamicin-resistant Pasteurella and Pseudomonas infections.
All that being said, self-medicating does carry a higher risk. Your main risk here is the infection getting worse. But yes, the one thing you need to remember- NO steroids in the eyes if there are any suspected ulcers or other problems.
