Timing of Initial ROP Screening in Preterm Infants
Initial ROP screening should be performed at 31 weeks postmenstrual age (PMA) OR 4 weeks chronological age, whichever is later. 1
Screening Initiation Based on Gestational Age at Birth
The timing of the first examination depends on how premature the infant was:
- Infants born ≤26 6/7 weeks gestation: Screen at 31 weeks PMA 2
- Infants born ≥27 weeks gestation: Screen at 4 weeks chronological age 2
- Use whichever timing comes later to ensure adequate retinal development for meaningful examination 1, 3
Who Needs Screening
Screen all infants meeting these criteria: 1, 2
- Gestational age ≤30 6/7 weeks (regardless of birth weight) 2
- Birth weight ≤1250 grams (regardless of gestational age) 2
- Some centers extend screening to infants with birth weight ≤1500 grams 2
Special populations requiring screening even if 29-37 weeks gestation: 1
- Infants with chronic lung disease of infancy (CLDI) 1
- Infants who were NOT medically stable (required supplemental oxygen) 1
Do NOT screen: 1
- Infants >37 weeks gestation at birth 1
- Infants 29-37 weeks who had a medically stable course without oxygen requirement 1
Evidence Supporting This Timing
The 31-week/4-week guideline is strongly evidence-based. In the landmark CRYO-ROP and LIGHT-ROP studies analyzing 4,460 infants, 99% of infants did not develop retinal conditions indicating risk of poor outcome before 31 weeks PMA or 4 weeks chronological age 3.
More recent data from extremely preterm infants (<27 weeks gestation) confirms this safety margin: no infants required laser therapy prior to 32 weeks PMA, and none had severe ROP detected before 31 weeks PMA 4. This validates that screening at 31 weeks PMA is appropriately timed even for the most vulnerable infants 4.
Common Pitfall to Avoid
Do not delay screening beyond these timeframes. While earlier screening (before 31 weeks PMA) has not proven necessary 4, delaying the initial examination risks missing rapidly progressive disease. Approximately 8% of premature infants overall require treatment, rising to 25% of those born <750 grams 5. In extremely low birth weight infants, 13% may have threshold ROP by their first examination if screening is delayed 6.
Follow-Up Examination Frequency
After the initial screening 1, 5:
- If ROP is present in Zone I or Zone II: Repeat examinations every 1-2 weeks 1, 5
- If no ROP or minimal disease: Follow ophthalmologist's recommendations, typically every 1-2 weeks until resolution 5
- More frequent examinations may be needed if disease is rapidly progressing 5
When Screening Can Be Discontinued
Stop screening when any of these criteria are met: 1, 7
- Complete retinal vascularization 1
- ROP regressing with vessels passed into Zone III on at least two sequential examinations 1, 7
- Infant reaches 45 weeks PMA without developing prethreshold ROP or worse 3
Critical Coordination for High-Risk Infants
For infants with chronic lung disease being discharged home with unresolved ROP, careful coordination of follow-up ophthalmology appointments is crucial 1. Missing appointments in infants with Zone I or Zone II disease can lead to missed treatment opportunities and preventable vision loss 1, 7.