Retinopathy of prematurity 1974-91. An analysis of the Danish Register for the Visually Impaired.

Registration of visual impairment is compulsory in Denmark for the age group 0-17 years. With birth years 1974-91 141 subjects were in the register with retinopathy of prematurity as basic disease, giving a frequency of 13.1 per 100 000 liveborn. Compared with other countries this is a high figure, and the trend over the period is a slight annual increase. Further analysing the data for trends in time the material was subdivided chronologically into thirds, each group comprising 47 subjects. Birth weight and gestational age showed a decline: median values in the three groups were 1250, 1100, and 960 g, and 30, 28, and 27 weeks, respectively. Associated CNS handicaps were recorded in 17, 38, and 34%. Visual impairment was serious in all groups, the median corrected acuity of the better eye being below 1/60. Geographically there was a striking shift towards a Copenhagen area preponderance of heavy ROP cases, with one of the two NICUs to account for the main part of registered cases in the most recent period.