Purpose: To test the effectiveness of our Canadian retinopathy of prematurity (ROP) screening guidelines as applied to high-risk premature infants.
Study design: Retrospective longitudinal cohort study.
Subjects: A total of 969 infants were examined longitudinally between 1991 and 2000 and 46 of these infants screened were treated for severe ROP.
Methods: Data from weekly ROP screening examination results were collected from a geographical area and analysed.
Results: The average incidence of severe ROP requiring treatment in the population of premature infants eligible for screening was 48.3 per 1000. In all, 46 infants were treated in this cohort. The mean gestational age (GA) was 25.5 weeks of age and the mean birth weight was 750 g. The mean chronological age (CA) and postmenstrual age (PMA) at the time of first screening was 36 days and 30.7 weeks, respectively. The first identification of any ROP in this group was at a mean CA 60 days and PMA of 34.1 weeks. The mean CA and PMA of the first observation of stage 3 were 74 days and 36.3 weeks. The mean CA and PMA at the time of treatment were 86 days and 37.7 week.
Conclusions: Our observations and analysis indicate the following ROP screening recommendations: infants of 28 weeks of GA or less, infants with a GA between 28 weeks and 30 weeks should have a single 'spot examination' at approximately 37 weeks of PMA (or prior to discharge from hospital) to include possible outliers; infants born with a birth weight of 1250 g or less; initial screening examination should be at 31 weeks of PMA or 4 weeks of CA, whichever is later; in the presence of any active ROP, the infant should be followed every 1-2 weeks; and stage 3 should be followed at least every 7 days.