Changes can indeed occur in the curve of the cornea during lactation.
Recently I went in for a contact check as my left contact seemed to be
"popping" and not seating correctly.  Upon examination, my optometrist
found that the curvature had changed since my last visit before my
pregnancy.  Interestingly, it was the same as when my first son was 6
months old (13 years ago), but had returned to its "normal" shape after
weaning.  When my doc suggested I just wait until I wean this baby (7
months) to consider new lenses, I took the opportunity to explain the
benefits of extended nursing, and then went ahead and got a new lens!

I would certainly consider postponing any eye surgery until a later
date.

Marie Simpson, IBCLC, LLLL
Kentucky USA