I think one should be somewhat skeptical of the claim that schizophrenia is completely absent in blind people; it might merely be more difficult to diagnose. Combined with the population of congenitally blind people being sufficiently small, the cases that might exist could escape notice. There was an informative post on Less Wrong about this
https://www.lesswrong.com/posts/z9Syf3pGffpvHwfr4/i-m-mildly...