Just to say I managed to set up the Nook Simple Touch with some test materials for my relative, but it seems this device is unsuitable for her condition, an advanced wet form of macular degeneration.
Font size was adjusted such that it could match or exceed what she uses in paper reading, and a variety of fonts were tested, including a monospaced font.
Research indicates that this result is not unexpected. See
www.ncbi.nlm.nih.gov/pmc/articles/PMC3650266/ ("Digital reader vs print media: the role of digital technology in reading accuracy in age-related macular degeneration", 2013), in which reading accuracy was compared across paper, an original iPad, and the Sony PRS-T1 ereader for patients with age-related macular degeneration. The ereader was found to give the worst results, the iPad the best.
My relative has not hitherto received any visual rehabilitation, but I am hopeful that she will now benefit from training in eccentric viewing and "steady eye" strategy.