What was his sickness?
If he had an eye injury, it's possible that this is a permanent scar.
If he had just developed that, I'd say optical mareks. But you say he had it since before four weeks (the usual earliest incubation period of mareks) and so, not knowing his illness, I'd be inclined to say this is less likely.
But can you describe what happened with his illness? How it appeared, how it progressed, how it cleared, and over what exact period of time (2 days to 3 weeks for example)?
If he's healthy otherwise, I would not worry about it and hug that chicken! Birds can survive quite well with one usable eye, and his looks more than functional - just cloudy.
If the shape of the pupil changes, then I'd suspect optical Mareks. Again he can potentially live a long full life with this. I had a rooster who had it (before I knew what it was) and lived for nine years at least! I just lost him to old age this year.
I'm guessing though that Wheezy had a respiratory illness?
I dunno - just a hunch.