Update on retinopathy of prematurity: the examination guidelines

Are we screening too many babies for retinopathy of prematurity?

A retrospective, hospital-records-based study of neonates screened for retinopathy of prematurity (ROP) was undertaken to determine whether the inclusion criteria for screening could have been safely altered to reduce the numbers of babies screened whilst not missing any stage III disease. Babies from six neonatal intensive care units in Birmingham were screened by a single examiner. Between November 1989 and November 1995, 1611 babies were examined and 1429 of these fell within the inclusion criteria of current guidelines for ROP screening produced by the Royal College of Ophthalmologists and the British Association of Perinatal Medicine--any baby < or = 1500 g birthweight or < or = 31 weeks gestational age. Thirty-nine (39) babies developed stage III ROP of which 31 (2.2%) were from Birmingham. In addition 8 babies with stage III ROP were referred from elsewhere. All 39 babies with stage III ROP had a birthweight < or = 1250 g or a gestational age of < or = 29 weeks, but 2 fell outside one criterion, indicating the need for both to be used. Had these inclusion criteria been utilised during this period, then 30% fewer babies would have been examined (432 of 1429). The importance of using both birthweight and gestational age as inclusion criteria is discussed, and the dangers of altering the indications for national screening on the basis of one study population is emphasised.

Retinopathy of prematurity in infants weighing 1000-1499 g at birth

OBJECTIVE

To review the incidence and severity of retinopathy of prematurity (ROP) in infants with birthweights 1000-1249 g and 1250-1499 g, to establish whether the upper weight limit for routine ophthalmological examination might safely be lowered.

METHODOLOGY

Prospective cohort study of infants born between 1 January 1977 and 31 December 1992 cared for in the neonatal nurseries at the Royal Women's Hospital, Melbourne. Data were retrieved on 1373 infants who survived their initial hospitalization. They comprised 657 with birthweights 1000-1249 g (group 1) and 716 with birthweights 1250-1499 g (group 2). There were 76 outborn infants in group 1 and 97 in group 2; the remaining infants were all born at the Royal Women's Hospital. Ocular examinations commenced at 2 weeks of age, when possible, and at 2-weekly intervals after that.

RESULTS

In group 1, ROP was detected in 14.6% (96/657) and severe ROP (bilateral stage 3-5) in 5.0% (33/657). Five (0.8%) children required surgical intervention (reaching threshold disease); following surgery, one was legally blind, one had severely impaired vision, and the other three had near-normal vision. Another child was blind; he was born at 28 weeks gestational age with a birthweight of 1170 g, and was transferred to a Level II hospital at 9 weeks chronological age with no detectable retinopathy. He returned 1 year later totally blind with detached retinae (grade 5 ROP). The prevalence of bilateral blindness in this group was 0.3% (2/657). In group 2, ROP was detected in 6.4% (46/716) and severe ROP in 0.8% (6/716). No children required surgery; three were found to be myopic at follow-up but the corrected visual acuity was normal. No children in group 2 were blind. No significant difference was found between the rates of ROP in inborn and outborn infants.

CONCLUSION

In neonatal units with similar rates of ROP and visual outcome, routine ophthalmological examination in the neonatal nursery of infants weighing more than 1249 g at birth is probably unnecessary.

Retinopathy of prematurity in discordant twins

Discordant twins may be at increased risk for retinopathy of prematurity (ROP) because of factors related to their unequal growth. Discordancy is defined as a difference of 15% or more in the birth weights of the two infants. We examined the data in 26 sets of discordant twins from six NICUs, including birthweight, gestational age, sex, and highest grade of ROP. Thirty-eight percent (10) of the lower birthweight infants had higher grades of ROP than their twin. Twenty-three percent (6) of the heavier birthweight twins had higher grades of ROP than their smaller siblings. Three infants reached threshold, and five were prethreshold. In every case, their twin siblings had mild or no ROP. Thirty-eight percent of the twins (10) had the same ROP outcome.

Screening for retinopathy of prematurity

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