My tortoise had the same case around 1 month before. I went to the fish stall to buy something called "turtle eyedrops" to it. It gradually improves and sometimes, I use cotton buds to clean her eyes if she's got some tissues on it.
The other useful thing is to put the tortoise under the sunshine for long. It could help them to cure the virus and get better.
BTW, tortoises might eat vegetables. It's good to give some vegetables to them everyday to keep them healthy. Especially those old tortoises. This is what the vet told me last time.