As stated in this quote, forget about what is realistically possible and go for the achievable. It will take a lot less time and it will be much more convincing. It would be well worth it to try and slide the parts of the eye over the vitreous body (Retina? Sorry I’m not an optical expert…) especially since, unless you have realistic veins (which I assume you won’t copying Pixar), as long as you fake it well, won’t be able to see the vitreous body actually move (because it hsould be all one color).
I have been venturing into Tex Avery style characters and have found it more convincing to model an oddly shaped eye with morph targets. Lattices won’t work. Your eye will keep shape until you venture beyond a certain radius. At that point it stretches your important parts of the eye and is not acceptable. You could spend weeks writing a script and fail than just doing it the old fashioned, hard and tedious way. When you think about the work involved in trying to shape the iris and cornea via lattices, sculpt deformers, or code you might as well make your eye one mesh and set up 30 morph tagerts, which, incidentally will only cost you a half days work if you are handy.
I know others will completely disagree. That’s fine. They probably know the right way to do it but when I asked the same question in a Maya forum 3 years ago I got the same responses you did. My technique was the only thing to solve it.
Sorry so long winded and if others think I’m steering you wrong, listen to them. I just have found no other way as of now?