The scientific mystery is confirmed by numerous studies.
Over the past 60 years, scientists have been grappling with a strange observation, Vice reports: no one has been able to find even one case of a person with schizophrenia who was born blind.
In 2018, a study at the University of Western Australia looked at nearly half a million children born between 1980 and 2001 and could not find a case.
And Tom Pollak, a psychiatrist and researcher at King’s College London, was also unable to find a single patient with congenital blindness who had schizophrenia.
The findings suggest that something about congenital blindness may protect a person from schizophrenia. What makes this even more surprising is that congenital blindness often results from infections, brain trauma, or genetic mutation — and those are all factors associated with greater risk of psychotic disorders.
Another strange fact: vision loss at other periods of life is associated with higher risks of schizophrenia and psychotic symptoms. And there are connections between vision abnormalities and schizophrenia, since visual abnormalities are often found before a person has any psychotic symptoms, sometimes predicting if a person will develop schizophrenia.