My chinese water dragon died unexpectedly, what happened?

I have had my chinese water dragon for 3 years, about 2 years ago he escaped his cage, and was injured while he was out. He broke his back to legs, and his hip. He seemed to have healed fine after about 6 months, and he was back to hunting crickets on his own, and moving around the cage regularly. Last night I had him out to feed him fruit, which we do regularly. He seemed fine, but one thing that I have noticed is that he has not shed his skin for close to a year, and he was unusually small for his age. After I got home from work I went to get him out. One of his eyeballs almost looked like it was eaten out, and you could see all the way into where his brain would be. The other eye was closed, but blackened out. I don't know what happened to him. He was on what seemed to be a good diet since we were able to feed him most fruit. The crickets came from Flukers Farms and they seemed pretty healthy. I fed the crickets lettuce, and gut stuffer calcium stuff. The little orange cubes. Why did my lizard die, and if we get another one, I want to make sure that I'm doing the right stuff. We also have an expensive lizard light that the vet recommended.