Objective: To study the effect of increased survival of infants <29 weeks' gestation on the incidence and severity of retinopathy of prematurity (ROP).
Methodology: Review of prospective records from 1986 to 1992 kept in the New South Wales (NSW) NICUS database on infants admitted to the neonatal intensive care units (NICU) in NSW. The survival rate and the incidence and severity of ROP on all infants <29 weeks' gestation admitted to the NICUs in NSW from 1 July 1986 to 31 December 1987 were compared to a similar group of infants admitted from 1 January 1992 to 31 December 1992.
Results: There was a significant difference in the survival rate of infants admitted between the two periods (235 of 376, 62.5% survival vs 255 of 336, 75.9% survival, respectively, P<0.0001). The odds ratio for survival adjusted for gestational age in the second period was 1.76 [1.24, 2.48 (95% confidence interval), P<0.002]. There was a slight increase in ROP in the second period (79 of 172 examined, 45.9% ROP vs 133 of 238 examined, 55.8% ROP, respectively). There was a rise in the number of infants with Stage 3 ROP in the second time period (14 of 172 examined, 8.1% ROP vs 41 of 238 examined, 17.2% ROP, respectively). However, fewer infants had detached retinas or > or = Stage 4 ROP in the second group [7 of 172, (4.1 %) vs 3 of 238, (1.3%), respectively]. This may be a reflection of the increase in the use of cryo- or laser therapy for Stage 3 ROP with 'plus' disease [2 of 172 examined, (1.2%) vs 18 of 238 examined, (7.6%), respectively].
Conclusions: With the increase in survival of the very preterm infant in recent years, there has been an increase in severe ROP (> or = Stage 3) in NSW. Despite the increased survival of the highest at-risk group (24- to 26-week gestation infants), there have been fewer cases of retinal detachment. There was also a rise in the number of infants receiving cryo- or laser therapy intervention.