For some reasons, VR headsets are known to improve myopia and crossed eyes. I don't know for cataracts but myopia don't seem to be a huge issue wrt VR uses.
As a layperson, that would be unsurprising if myopia is being caused due to short focal distances. It's not like your eyes are actually focusing on something an inch or two in front of them. As far as they're concerned, they're looking at something potentially several feet (or miles!) away.
