Why are they blind?
D000293:Adolescent; D000328:Adult; D001766:Blindness / Q000209:etiology*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D011247:Pregnancy; D014481:United States