My father only had sight in one eye after a retina detachment when he was young. The 'good' eye was very short sighted requiring a glasses lens which only had actual lens in the centre. If it carried on to the edge it would have been a couple of inches thick. Later he had a contact lens which was two or three Dioptres stronger than the manufacturer officially made them.
After a cataract operation in which the old lens is ultrasonically destroyed then removed by syringe and a new lens implanted - all through a 2mm cut, he had perfect vision from arm's length to infinity and only needed reading glasses. He spent several months just walking around looking at things seeing them clearer than he had for fifty years.