@thegreatmuta92: I would definitely recommend a 17in laptop if you have visual impairment. Then run it at 720P with a higher default text and app size(150% to 200%). You should have a great deal of options for making it readable for you.
I'm not sure why you want a convertible laptop, but those will generally run smaller and make reading a possible issue.
17in would be a great laptop size for me for computer usage, but reading vertically formatted textbooks on a horizontally oriented laptop with a keyboard in the way kind of sucks. Maybe the 17 inch screen could make it better (I've never used one that big). I wish I could just turn it vertical and tuck the keyboard away when reading textbooks.
I've been trying to supplement paper reading with a tablet for a while now, but the last tablet I got was 9.7 inches and was too small (and weak) to use for reading textbooks with massive amounts of text. The idea of a big, 15.6 inch touch screen with laptop power allures me. But it just might not be worth it right now.