At one of my previous contract jobs the lead software developer was classified as "profoundly blind". Basically he did not even have light perception, yet he was able to write complex software for the JC Pennies chain.
He did it by using a Braille reader that was placed either above or below his keyboard. Using this reader he could read one line of text at a time and used his keyboard to navigate around the screen... even though he could not actually "see" the screen.
If I were to have gone blind I would have retired on disability.