People with Nystagmus are often fairly slow readers, but they can still read. However they may become tired more easily than most, depending on the size of the writing.
I can read the smallest writing in the box above but it takes me about twice as long to read it than the biggest writing in the box above. Although I am slightly slower than everyone else I manage.
I have to hold a book very close to my eyes when reading as it is more comfortable and makes it easier for me to read. Everyone with Nystagmus has a point where their eyes stop moving. You can discover this point by holding out your index finger at arms length, and gradually move it closer to you while continually concentrating on it. Make sure someone is watching, they can tell you when your eyes stop moving. It is at this point that things become in focus, and this is where I hold a book when reading. I cannot focus when my eyes are moving constantly.