If you have a physical disability in addition to sight loss, then there are special keyboards or special programs which can help, but some of them can take some time to learn, and do take some persistence. Programs which allow you to talk to the computer to give it instructions are available, but often the better ones are expensive and were not designed to be used together with screen reading software for people with a sight loss. For visually impaired people they do not make using the computer easy - if anything, it requires quite a bit of knowledge about computers to be able to get the best out of them, and quite a bit of help in setting up. Computing for people with a multiple physical disability is a very specialized field and the best thing is to get a specialized worker to help with some advice, and not just buy some software off the shelf. Not at all.
Screen readers can work with many types of programs.
Word processors, spreadsheets, databases, the Internet, e-mail, all sorts of things. The deciding factor tends to be whether there is a way of using the program with the keyboard and whether there is text on the screen for the screen reader to read out. I can get bigger fonts on my computer. The bigger fonts are only in the editing areas. Menus and icons and boxes with messages will all be in the standard size, so although typing will be easier, using the program itself will be difficult.