When did the narrator's mother turn blind in "The Leap"?

We are not actually given precise details of how and when
the narrator's mother turned blind, however we can infer quite a bit from the text. What
is tricky about this story is the way that it uses flashbacks to narrate the content,
which means that it starts off in the present, with the narrator talking about her old,
blind mother, but then goes back to specific events that occurred in the past--one of
them even before the narrator was born. However, it is clear that when the story begins
in the present, the narrator's mother is blind, as the result of "encroaching and
stubborn cataracts." However, she still maintains the same "catlike precision" that she
had in her youth.

We can infer from the way that the
flashbacks are narrated that this blindness has only started recently, as it would have
been immensely difficult, if not impossible, for the narrator's mother to save the
narrator from the burning house if she were blind. You might benefit from re-reading the
story and paying particular attention to the flashbacks and how and when they are
introduced to try and keep track of the chronology of this great story. This should help
you to understand it better.