Dear Editor,

We were interested to read the article of Vyas et al (1) on the incidence of severe retinopathy of prematurity (ROP) in 11 neonatal units (NUs) from five cities in England in 1994. We have published similar data from 8 NUs in New South Wales (NSW) Australia in 1993 and 1994.(2) These data were prospectively collected in the NSW Neonatal Intensive Care Unit's data collection and is stored and maintained in the NSW Centre for Perinatal Health Services Research, University of Sydney, NSW.

For infants <_29 weeks="weeks" gestation="gestation" there="there" was="was" no="no" significant="significant" difference="difference" in="in" severe="severe" rop="rop" greater="greater" than="than" or="Stage" _3="_3" between="between" the="the" _5="_5" cities="cities" england="england" and="and" nsw="nsw" australia="australia" table.="table." p="p"> Table: Incidence of severe ROP in the 5 cities in England and NSW, Australia.

*= Number with severe ROP/number examined and the percent in parenthesis.

Unlike Vyas et al (1) we could not find an association between improved survival and the development of severe ROP. In 6 of the NUs in our study survival in infants <_27 weeks="weeks" gestation="gestation" ranged="ranged" from="from" _51.3="_51.3" to="to" _68.8="_68.8" two="two" nus="nus" have="have" been="been" excluded="excluded" this="this" analysis="analysis" as="as" they="they" are="are" childrens="childrens" hospitals="hospitals" and="and" very="very" few="few" small="small" premature="premature" infants.="infants." the="the" percent="percent" with="with" severe="severe" rop="rop" for="for" lowest="lowest" highest="highest" survival="survival" was="was" _15.1="_15.1" _3="_3" _20="_20" _23.8="_23.8" _5="_5" _21="_21" respectively="respectively" while="while" range="range" of="of" in="in" _6="_6" _36.0="_36.0" _9="_9" _25.="_25." infants="infants" _27-28="_27-28" _85.1="_85.1" _96.7="_96.7" _7.1="_7.1" _4="_4" _56="_56" _3.4="_3.4" _2="_2" _58="_58" respectively.="respectively." group="group" _2.01="_2.01" _50="_50" unpublished="unpublished" observations.="observations." we="we" also="also" shown="shown" that="that" despite="despite" an="an" increase="increase" preterm="preterm" following="following" introduction="introduction" surfactant="surfactant" there="there" no="no" significant="significant" impact="impact" on="on" incidence="incidence" or="or" severity="severity" rop.3="rop.3" p="p"> In infants 29-31 weeks' gestation, 6 of 443 (1.4%) developed severe ROP and one infant required Cryo/Laser therapy.(2) This infant was 30 weeks' gestation with a birth weight of 1305 grams. We therefore agree with Vyas et al (1) that there should be no reduction in the upper limit of gestation or birth weight for screening for ROP.

David A Todd
Neonatal Unit
The Princess Anne Hospital
Coxford Road
Southampton, Hants, UK

John Kennedy
Ophthalmology Department
Westmead Hospital
Sydney, NSW
Australia

1. Vyas J, Field D, Draper ES, Woodruff G, Fielder AR, Thompson J, Shaw NJ, Clark D, Gregson R, Burke J, Durbin G. Severe retinopathy of prematurity and its association with different rates of survival in infants less than 1251 g birth weight. Arch Dis Child Fetal Neonatal Ed 2000;82:F145-F149.

2. Todd DA, Cassell C, Kennedy J, John E and the NSW Neonatal Intensive Care Unit's study group. Retinopathy of prematurity in infants <_32 weeks="weeks" gestation="gestation" at="at" birth="birth" in="in" new="new" south="south" wales="wales" _1993="_1993" and="and" _1994.="_1994." j="j" paediatr="paediatr" child="child" health="health" _199935355-357.="_199935355-357." p="p"> 3. Kennedy J, Todd DA, Watts J, John E. Retinopathy of prematurity in infants less than 29 weeks' gestation: 3 1/2 years pre- and postsurfactant. J Pediatr Ophthalmol Strabismus 1997;34:289-292.

Wonderful work by Vyas et al on ROP and its incidence in different cities of Britain. The statistically significant difference in the incidence of ROP in different centres may be related to the differences in the level of care provided. The advancements in neonatal care, particularly the use of surfactant and the resultant reduction in the requirements of O2 has greatly influenced outcome and possible development of ROP (Hussain et al, Pediatrics 1999). Obviously all factors need to be taken into account while comparing results at widely differing centres.