I would get a good eye test done, maybe she has issue's with certain colors, and if so, maybe wearing a colored lens might help her see things better
that and try to get her to focus more on movement then and NOT just look for a DEER
once she finds movement, have her use binoculars to ID things better than!
and I woudl also make sure she is 110 % sure of any targets and what's behind them before shooting
poor eye sight can be dangerous when holding a weapon!