Retinopathy of Prematurity

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Retinopathy of prematurity, ROP, is a disease of premature babies and a major cause of blindness in developed nations. Incidence is inversely proportional to birthweight. It is now known that oxygen exposure during early life is not the only risk factor for developing the condition. Screening is essential, and close follow-up required.



28-30 weeks in embryological life is a period of retinal vascularisation. Retinal growth diminishes from 30 weeks, reducing the risk of disease development.

Risk Factors

The following neonates are at risk and require screening, usually at 6 weeks of life.

  • Very low birth weight' neonates (<1.5kg)
  • All neonates born <32 weeks
  • 'High risk' neonates 1.5-2kg / >32 weeks, eg:
    • those who required cardiorespiratory support
    • clinical instability
  • Supplemental oxygen therapy
  • Other risk factors largely unknown.


Diagnosis is by ophthalmological screening using mydriatics and opthalmoscopy.

International Classification of Retinopathy of Prematurity (ICROP)

Stage denotes severity of disease.

  • Stage 1: reduced blood supply to peripheral retina with a clear demarcation line. Usually resolves spontaneously without sequelae.
  • Stage 2: Demarcation line thick and ridged. Damage remains in peripheral retina.
  • Stage 3: Neovascularisation: vessels at risk of contracting and precipitating stage 4 disease.
  • Stage 4: contracting vessels initiate retinal detachment.
  • Stage 5: full retinal detachment.

Zone denotes the area of the retina affected.

  • Zone 1: the central retina including the macula. Disease here is critical and requires close monitoring / treatment.
  • Zone 2: a circle surround zone 1.
  • Zone 3: a temporal crescent not included in zone 2.


  • Stage 1: close monitoring. No treatment.
  • Stage 2: close monitoring. No treatment.
  • Stage 3: laser photocoagulation. Close follow-up and monitoring.
  • Stage 4+5: Vitrectomy or 'scleral buckling' may be considered.


  • Disease progression
  • Visual impairment
  • Blindness

  • Complications of treatment
    • Inflammation and discomfort
    • Bleeding

All premature babies are at risk of developing:


  • Stage 1+2: Does not lead to blindness but can progress.
  • Stage 3: 80% have good vision.
  • Stage 4 + 5: high risk for substantial or total loss of vision.


Stages 3-5 require ophthalmology follow-up at decreasing intervals until age 5.

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