Visual impairment in Swedish children. II. Etiological factors.

The analysis of etiological factors in a group of visually impaired children is of considerable importance when trying to find guidelines for possible preventive work. In this study we present etiological data on 2373 Swedish children. Data have been obtained by reviewing medical records on all known children with visual impairment throughout the country. In accordance with similar studies from industrialised countries, the group with prenatal etiology was the predominant, comprising 64% of the material. Within this group, half the patients had a disease of genetic origin. A total of 50% of all patients with prenatal etiology had an additional impairment, but in the group with diseases of genetic origin this proportion was smaller, only 40%. On the other hand, many children with additional impairments were found among those with an unspecified prenatal influence. Peri-/neonatal etiologies were found in 20% of the patients. In this group as many as 83% had additional impairments. This was even more pronounced among children delivered at term. The group with infantile/juvenile etiologies was small, 7%, with additional impairments in 66%. In 9% of all patients the etiology was classified as unknown. Among these, 80% had additional impairments. The visual impairment tended to be more pronounced, the later the disease was acquired. A male preponderance was seen in most etiological subgroups and in the material as a whole.