Ah Gracey, so sorry for your friend. :( What a challenge to undergo.
I'm sure there's plenty of information on the 'net, and perhaps a support group or two? So be sure and Google the term.
What I know I read in a novel, actually, as a character had it. The author definitely researched it thoroughly. What the character experienced was a gradual limit to their peripheral vision. It wasn't a fading away type degeneration, but more like certain "spots" of vision were gone, if you see what I mean. They could actually see enough to take in a lot of data and get around.