A track ball is a wonderful alternative to a mouse and can be
manipulated with a hand, head stick or even with one's chin and nose.
(Are you reading this GB? Don't forget to wipe your chin ;-) There are
many different styles of track balls so it might take some looking to
find the one that will fit the individual's needs. Take her to the store
and try each one until you find the one that feels right. As for the
vision impairment, if you are using windows, go to the accessibility
folder and you should be able to find larger and different colored
cursors to use. Also, there is a setting for adding "trails" that follow
the movement of the cursor to help in seeing it's motion. If you need
any further explanation or help feel free to ask, either on the list or
off. I hope this helps.
Jim