TABLE 1:

Basic characteristics of eight population-based studies of retinopathy of prematurity (ROP)

First author (reference)	Entry criteria for ROP* screening	Era of screening	Country or region of origin	Follow-up rate
Saigal et al 1984 (12)	Birth weight 501 to 1000 g	1977 to 1980	Ontario, Canada	92%
Ng et al 1988 (10)	Birth weight 1700 g or less and survived three weeks or longer	1985 to 1987	Three health regions, Great Britain	93%
Darlow 1988 (11)	Birth weight 500 to 1499 g and survived	1986	New Zealand	93%
Fledelius 1990 (9)	Birth weight 2 kg or less, or gestation 34 weeks or less and “risk factors not specified”	1982 to 1987	Frederiksborg County, Denmark	Unknown
Holmström et al 1993 (6)	Birth weight less than 1500 g and survived eight weeks or longer	1988 to 1990	Stockholm County, Sweden	88%
Barnekow and Stigmar 1993 (8)	Gestation less than 33 weeks or birth weight 1500 g or less	Unknown	Region of southern Sweden	90%
Maly 1993 (7)	Gestation less than 33 weeks or birth weight less than 1500 g	1986 to 1990	Malmö, Sweden	90%
Haugen and Markestad 1997 (13)	Birth weight less than 1500 g	1989 to 1993	Two counties in western Norway	85%