To describe the prevalence, diagnoses and aetiologies of visual impairment in children with developmental delay (DD) in a Danish county with a population of 618 000 citizens.Methods
We carried out a cross-sectional study in Copenhagen County of children aged 4–15 years with profound to borderline DD (IQ ≤ 80). Children were located through school psychologists or paediatric clinics. The number of children with DD was estimated using the capture-recapture method.Results
A total of 1126 children fulfilled the inclusion criteria, corresponding to 97.7% of the estimated number of children with DD in the county. Ophthalmological examinations were performed in 923 children. The prevalence of visual impairment was 10.5% in the study group and 22.4% in those with an IQ ≤ 50. The diagnoses were predominantly cerebral visual impairment, optic atrophy, retinal dystrophies and congenital nystagmus. The aetiology of visual impairment was prenatal in 54 children, perinatal in 29 children and postnatal in seven children.Conclusions
Visual impairment is highly increased in children with DD and is correlated to low IQ.