What are the risk factors for retinopathy of prematurity (ROP)?

Risk Factors for Retinopathy of Prematurity (ROP)

The primary risk factors for retinopathy of prematurity are low birth weight (<1500 grams), prematurity (≤34 weeks gestational age), and prolonged oxygen therapy. 1

Key Risk Factors

Major Risk Factors

• Low birth weight (<1500 grams) 1, 2, 3
• Prematurity (gestational age ≤34 weeks) 1, 3
• Oxygen therapy (especially prolonged duration) 1, 2, 4, 5
• Mechanical ventilation 2, 5

Additional Risk Factors

• Multiple gestation 5
• Septicemia 4
• Apnea episodes 4
• Blood transfusions 4, 5
• Resuscitation at birth 5
• Delayed regaining of birth weight (>10 days) 5
• Unstable clinical course 1
• Hyperoxia and hypoxia fluctuations 2
• Respiratory distress requiring prolonged oxygen support 1

Pathophysiology

ROP develops through a two-phase process:

1. Phase I (Hyperoxic Phase):

   • High oxygen levels cause cessation of normal retinal vessel development
   • Regression of immature capillaries
   • Formation of a central zone of vaso-obliteration
   • Suppression of VEGF (Vascular Endothelial Growth Factor) by oxygen inhibits normal vessel growth 1, 6

2. Phase II (Hypoxic Phase):

   • Hypoxia-induced pathological neovascularization
   • Elevated levels of VEGF drive abnormal vessel growth
   • As infants mature, rising levels of IGF-1 allow VEGF-stimulated pathological neovascularization 1, 6

Screening Recommendations

The American Academy of Pediatrics recommends screening for:

• Infants weighing less than 1500 grams OR
• Infants with gestational age ≤34 weeks
• Infants with unstable clinical course and higher birth weight/gestational age may also require screening 1

First examination should occur at:

• 31-33 weeks postmenstrual age OR
• 4 weeks chronological age, whichever is later 1

Prevention Strategies

1. Prevention of premature birth when possible
2. Judicious oxygen therapy with careful monitoring of oxygen saturation levels
3. Prevention and prompt treatment of sepsis
4. Careful monitoring of blood transfusion practices
5. Appropriate management of respiratory distress

Treatment Options

For threshold ROP requiring intervention:

• Peripheral retinal ablation/laser photocoagulation (gold standard treatment)
• Anti-VEGF therapy (emerging alternative, particularly for Zone I disease)
• Surgical intervention for advanced ROP with retinal detachment 1

Follow-up and Monitoring

• Regular retinal examinations until vascularization is complete
• Follow-up examinations every 1-2 weeks for infants with vessels/ROP in Zone 1 or Zone 2
• Less frequent examinations when vessels have reached Zone 3 with regression on two sequential examinations 1

Understanding these risk factors is crucial for implementing preventive strategies and ensuring timely screening and treatment of ROP in high-risk infants.