Surveillance for retinopathy of prematurity in a Danish country. Epidemiological experience over 20 years.

Purpose: An updated analysis of the trends in a Danish county regarding retinopathy of prematurity (ROP), outlining its natural history over the years 1982-2001.

Methods: Epidemiological data are given of the 132 infants in the county with birth years 1998-2001 prospectively under surveillance for ROP. The customary national screening limits of gestational age (GA) and birthweight (BW) of 32 weeks/1750 g were generally adhered to. The findings are compared to five previous consecutive reports of a similar set-up, now making a total of 1123 who have been under surveillance.

Results: With focus on the 20 years' newborns at a higher risk for ROP in the county (GA/BW both under the above limits; n=591) the continuous improvement up to 1998--as reflected by ROP frequency, its severity, and risk levels according to GA/BW--appears to have been interrupted. Compared to the previous 4-year period, the percentage acquiring ROP in 1998-2001 increased from 10 to 31%, and four recent cases qualified for retinal ablation therapy, compared with zero in the previous 4-year period. However, there were no advanced stages (of at least ROP 3) in infants above 30 weeks/1500 g at delivery.

Conclusions: (a) Using the ROP also as a neonatal treatment quality parameter, the present trend (progress stopped) should be followed attentively. So far, we have no clues regarding therapy-related or other causality. (b) Despite the suggested worsening, a lowering of the ophthalmic GA and BW screening limits now seems justifiable. With a view also to the high-risk Copenhagen data and the national childhood visual impairment register, a reduction of the values to 31 weeks/1500 g should be considered.