Table 3 Stages 4 and 5 retinopathy of prematurity (ROP) by gestational age groups and time epoch.

Gestational age	1992–94	1995–97	1998–2000	2000–02
22–24 weeks
Stage ⩾4/survived	0/41 (0)*	2/53 (3.8)	1/55 (1.8)	3/76 (3.9)
Stage ⩾4/stage ⩾3	0/17 (0)†	2/16 (12.5)	1/23 (4.3)	3/41 (7.3)
25–26 weeks
Stage ⩾4/survived	2/210 (1.0)	1/268 (0.4)	2/249 (0.8)	3/238 (1.3)
Stage ⩾4/stage ⩾3	2/55 (3.6)	1/56 (1.8)	2/41 (4.9)	3/46 (8.7)
27–29 weeks
Stage ⩾4/survived	5/729 (0.7)	0/737 (0)	2/747 (0.3)	0/707 (0)
Stage ⩾4/stage ⩾3	5/30 (16.6)	0/15 (0)	2/19 (10.5)	0/17 (0)

All results are expressed as total survivors.

Values are n/N (%).

*Stage ⩾4 ROP/survived (percent survival); †stage ⩾4 ROP/stage ⩾3 (percent of severe ROP).