deafdyke,
Schools for the blind accept children who have visual acuity from 20/70 (visually impaired) to total blindness.
I know several people who attended a state school for the blind and received special diplomas. Some of the academic curricula of schools for the blind do not follow the "regular" academic standards of public schools. In some cases (not all), academic instruction is several years below grade level. For example, at the school for the blind in my state, a few seniors were learning how to count money. To be fair, I don't know if there were extenuating circumstances that may explain why this skill wasn't learned at an earlier age.