Description

Retinopathy of prematurity (ROP) is an abnormal pattern of retinal vascularization of preterm infants leading in some cases to permanent visual loss and blindness as well as many other eye problems.

Epidemiology

• ROP is the leading cause of blindness among children in the developed world:
  • 0.2% of all infants born in the United States
  • 20% of infants born <1,500 g
• 1,300 develop severe disease requiring treatment annually in the United States.
• Birth weight and ROP (frequency of ROP stage 1 or greater)
  • <750 g: 90%
  • 750 to <1,000 g: 78%
  • 1,000 to 1,250 g: 47%
  • >1,250 g: <1%
• Gestational age and ROP (frequency of any ROP stage 1 or greater with BW <1,251 g)
  • ≤27 weeks: 83%
  • 27 to 31 weeks: 55%
  • ≥31 weeks: 29%

Risk Factors

• Gestational age
• Hyperoxia
• Hypoxia
• Acidosis
• Hypercarbia
• Apnea
• Bradycardia
• Nutritional deficiencies
• Ambient light
• Intraventricular hemorrhage
• Lower birth weight
• Lower gestational age
• Multiple gestation
• Born at another facility and transferred

Pathophysiology

• Normal retinal vascularization begins at the optic disc at about 16 weeks postmenstrual age and is typically completed at about term.
• Preterm delivery exposes the actively growing vessels to unusual conditions. These alter production of vascular endothelial growth factors (VEGFs). In some cases, the vascular growth stops and then resumes normally, whereas in other cases, the retinal blood vessels grow abnormally off the surface of the retina.
• The timing for development of acute ROP is related to postmenstrual age and not chronologic age or birth weight. It is rare to see any acute ROP prior to 32 weeks’ postmenstrual age.
• Although the incidence of ROP increases with decreasing birth weight, fewer than 10% of babies smaller than 1,250 g birth weight will have ROP sufficiently severe to require treatment.