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Retinopathy of Prematurity

URGENT — Retina

Symptoms

  • asymptomatic in neonates: screening is the only way to detect early stages
  • leukocoria (white pupil): seen in advanced stage 4 or 5 retinal detachment
  • nystagmus or poor tracking: indicates significant bilateral visual impairment
  • high myopia: ex-preemies often develop severe nearsightedness as they grow

Clinical Findings

Screening criteria (AAP/AAO)

  • birth weight ≤1500 g OR gestational age ≤30 weeks
  • first exam: at 31 weeks postmenstrual age or 4 weeks old (whichever is later)

ICROP-3 classification (2021)

  • zones: I (posterior pole), II (mid-periphery), III (temporal crescent)
  • stages: 1 (line) → 2 (ridge) → 3 (fibrovascular growth) → 4/5 (detachment)
  • plus disease: dilated/tortuous vessels in ≥2 quadrants (the key treatment trigger)
  • aggressive rop: flat, rapidly progressive neovascularization in the posterior zone

Late sequelae

  • macular dragging: temporal displacement of the fovea by scar tissue
  • lifelong risk: high myopia, strabismus, and rhegmatogenous retinal detachment

Etiology

Pathophysiology

  • phase 1: relative hyperoxia after birth halts normal vessel growth
  • phase 2: the avascular retina becomes hypoxic and overproduces vegf
  • result: abnormal, fragile new vessels grow at the vascular-avascular junction

Risk factors

  • low birth weight and gestational age (most critical factors)
  • supplemental oxygen exposure, sepsis, and frequent blood transfusions

Red Flags

  • plus disease: indicates high metabolic demand; requires treatment within 72h
  • zone i stage 3: high risk of rapid progression to detachment
  • stage 4/5 (detachment): requires emergent surgical intervention (vitrectomy/buckle)
  • missed screening: the window for effective treatment is extremely narrow

Investigations

Screening protocol

  • dilated fundus exam with scleral depression (use speculum and depressor)
  • pupil dilation: combined phenylephrine 1% and cyclopentolate 0.2%

Documentation

  • precise recording of zone, stage, extent (clock hours), and plus status
  • retinal imaging: wide-field cameras (e.g., RetCam) for baseline and serial follow-up

Treatment

Type 1 ROP (requires treatment)

  • zone i: any stage with plus, or stage 3 without plus
  • zone ii: stage 2 or 3 with plus

Modalities

  • laser photocoagulation: ablate the avascular peripheral retina to stop vegf production
  • intravitreal anti-vegf (bevacizumab): often first-line for Zone I disease
  • surgery: vitrectomy or scleral buckle for stage 4 and 5 detachments

Clinical Pearl

Three ROP epidemics: 1940s-50s (oxygen), 1970s+ (neonatal advances), 1990s+ (LMICs). ICROP3 (2021) classification: zone + stage + vascular characteristics. Plus disease = dilated tortuous vessels in ≥2 quadrants. Anti-VEGF preferred over laser for Zone I disease (lower recurrence, preserves peripheral vascularization). BEWARE reactivation months to years after anti-VEGF. Screening: BW ≤1500g or GA ≤30 weeks.

Differential Diagnosis

  • • fevr (familial exudative vitreoretinopathy) — similar appearance but full-term birth
  • • norrie disease (genetic, bilateral retinal masses/detachment)
  • • coats disease (unilateral, usually older male children)
  • • persistent fetal vasculature (pfv)

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