I had advanced retinopathy which I thought was incurable (as in, can stop it getting worse but can't get any better) but after lots of laser and an eye op, I saw the photos of my eyes with the doc and was astounded that a lot of the damage (cotton wool spots, exudates) is no longer there.
Also I used to get this flicker sensation in my vision first thing in the morning, as the blood supply to the eyes was impaired, but now this has gone (as there is less retina to supply with blood I suppose, the laser took a lot out)
So retinopathy can be reversed even at advanced levels.