In general there is a machine for the visually impared among the voting machines.
And if a poll worker does help, they are supposed to do it in pairs, one democrat and one republican. At least in Ohio and in theory, and for the most part in practice.
They always try to get him to use the SPECIAL MACHINE, and his response is, sometime when i have TIME i will try your special machine, but right now i am trying to get to work, so can my wife just go in with me and help me cast it.