I initially got into technology because I worked with a lot of students and my own children who had learning issues. Many of my students gave a tremendous sigh of relieve when first allowed to compose documents on a computer (spell checker, lack of fatique from handwriting for people who had dysgraphia, ease of reading computer text, coloured text is easier for some dyslexics to read).
My daughter is severely learning disabled and her first computer allowed her to write stories and screen plays that astounded her classmates and teachers who had viewed her up to that point as stupid. Today she is a film maker who reads voraciously but still prefers to do it online. Her 2 year old daughter recently was given her own iPad because her parents were tired of sharing their's with her. She moves freely between her iPad books and her paper books.
So based on my unscientific observations, e-books may make reading more accessible to those who find reading difficult.