Screening for Retinopathy of Prematurity: Optimal Timing of First Examination

Hwang, Wi Kyung; Kwan, Soon Lyoul; Kim, Heng Mi

Abstract

PURPOSE
Early detection and proper treatment of retinopathy of prematurity (ROP) is crucial. The postnatal age of 4-6 weeks has been considered the most optimal time to screen the high risk infants for ROP. However, ROP rarely appears even before this period of age and we experienced several cases ROP detected before 4 weeks of age at NICU of Kyungpook University Hospital. This study was conducted to evaluate the most optimal time of first ophthalmic examination for ROP screening.
METHODS
A retrospective analysis of ROP screening records of 106 infants who admitted to the NICU of Kyungpook University Hospital from January 1996 to March 1999 was performed. Infants with a gestational age <34 weeks, birth weight <1,500 gm and perterm infants who exposed to supplemental oxygen were included in this study. ROP infants were grouped according to birth weight : Group I (birth weight > or =1,500 gm) and Group II (birth weight <1,500 gm). Ophthalmic examinations were commenced between 3 weeks and 6 weeks postnatal age and recorded using the International Classification of ROP.
RESULTS
Out of 106 infants screened, 35 infants were found to have some degree of ROP in at least one eye on at least 1 occasion. Of 35 infants with ROP, 11 infants were screened before the postnatal age 4 weeks. Eight ROP, including one stage 3 ROP, were detected at this first ophthalmic examination. Review for the time of first detection of ROP by postconceptional age revealed that stage 3 ROP and threshold ROP did not develop before 34 weeks. Postnatally ROP developed and progressed earlier in Group I than in Group II. The time of onset and highest stage represented by postnatal age in Group I and II were 28+/-7 days, 57+/-19 days and 32+/-15 days, 69+/-26 days respectively. The time of onset and highest stage represented by postconceptional age in Group I and II were 35.4+/-2.3, 36.3+/-2.9 weeks and 36.0+/-1.6, 38.0+/-3.6 weeks respectively, revealed no significant difference between two groups.
CONCLUSION
These data indicate that the time of onset and progression of ROP are correlated more closely with postconceptional age than with postnatal age. In other words, the postconceptional age is superior to postnatal age in determining when to initiate ROP examination. Our study suggests that screening infants at 34 weeks postconceptional age seems to reliable for early detection of severe ROP in larger, and more mature preterm infants.