I have volunteered and worked with the CNIB here in Canada over the years (not to mention Mum has worked there over 37 years.. retiring this summer)... I have worked around many visually impaired children and adults and have learned about the condition your friend has. One thing I do know is they love anything that is tactile. Something they can really feel with their hands. yes I agree that Rag quilting would be really nice idea. Make your own chenille is another great idea to put into blocks. Applique and 3D applique is also a good idea.
If you went with a crazy patch quilt idea, find fabrics of different textures, shiny, coduroy, denim, velvet, velveteen, soft baby style fabrics.. (I think one is called Cabbage Roll).
I used to do fabric crafts with the children at the summer camps in Central Newfoundland and we played alot with many tactile fabrics and other textiles.
I hope this helps. If I can think of anything else, I will let you know!
Cheers
Andrea