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I don't think that these drugs alone are going to cure it for you. And kittens should NEVER be given Terramycin because it can cause severe tooth staining and other problems.
If the problem is serious, my vet would put the cats on one of the antiviral drugs such as acyclovir (Zovirax), vitamin A and lysine, and tetracycline (Terramycin used only in adult cats) ophthalmic ointment or oral doxycycline (Vibramycin).
Keep in mind that these symptoms can be because of herpes virus. In this case, they could need supportive care for a lifetime.
These drugs that you have will not only be ineffective but they can also hurt the cats.
Let me know if you have more questions about this.