That's some really cool information. I've read through the second study, and it seems that condition is dependent on the plasticity of the lenses of your eyes. Children can adapt to it and learn, but lose the ability as they grow older. I imagine that despite that, it's still possible to adapt and become accustomed to looking underwater to some degree while swimming. But don't expect perfect vision either. However, some myopic folk's visual acuity is bad enough that the deformity of their retinas allows them to see underwater is if they had perfect vision!