Individuals with a diagnosis of complete congenital or acquired blindness will be recruited from the community and associations that offer assistance to individuals with visual impairment. The characterization of blindness will be based on the classification of the degree of visual impairment proposed by the International Statistical Classification of Disease and the 10th Edition of the International Classification of Disease, in which visual acuity <20/400 or <20/200 in the better eye is classified as blindness.