Taking the previous commentor's bait...
Ah, c'mon. We have - at least for now - changed the way evolution "works" for human beings because, in no small part, we generally don't penalize something like poor eyesight at an older age by keeping the holders of those "deficient" genes from reproducing at a younger age. Until there is pressure on the population - e.g., superior lens flexibility at old age somehow becomes a survival requirement at a younger, pre-childbearing age - you won't see people evolve.
Where such pressure could come about in a more realisitic setting - if you call Science Fiction and/or true colonization of the moon or Mars "realistic" - might be in the selection process of the candidate colonists. If the colonists are chosen in any way besides truly randomly, then they will represent a branch that has taken at least one step in an evolutionary way. I.e., if certain genes weren't present in the selected group, they won't likely appear on their own down the road.