How long can uveitis persist before there can be a permanent eye damage?

Hello doctor,

My daughter has been diagnosed with posterior idiopathic uveitis, and she also has type one diabetes. The diagnosis was made about six weeks ago, and three weeks ago she was put on Prednisone, but I am not sure. Her eyesight was originally blurred around the periphery, which became clearer after she went on the treatment. But, it became distorted as if she was looking through a funhouse mirror, but is still improving. Since she has begun tapering the medicine, the doctor told her the condition is turning worse, although not as bad as it was. She is scheduled to go in a week from today to discuss other options, among them, injections directly into the eye. Through reading about uveitis on websites, this seems to be the correct flow of treatment regimen. My question is, how long can this condition persist before there can be a permanent eye damage? Is it possible to ascertain?