Retinopathy of Prematurity

ROP: Intro & Pathophysiology - Preemie Eye Peril

• Definition: Proliferative retinopathy in premature, low birth weight (LBW) infants due to incomplete retinal vascularization.
• Pathophysiology: Biphasic process.
  • Phase 1 (Hyperoxic/Vaso-cessation): Postnatal ↑O₂ (esp. therapy) → ↓VEGF → delayed normal vessel growth, potential vaso-obliteration.
  • Phase 2 (Hypoxic/Vasoproliferative): Expanding avascular retina → relative hypoxia → ↑VEGF → abnormal neovascularization at vascular/avascular junction.
• Key Risk Factors:
  • Prematurity: Gestational Age (GA) < 32 weeks
  • LBW: Birth Weight (BW) < 1500g
  • Oxygen therapy (duration, concentration fluctuations)
  • Sepsis, poor postnatal weight gain, blood transfusions.

⭐ The temporal retina is most commonly affected and is the last to complete vascularization, making it particularly vulnerable in ROP development.

ROP: Classification - Mapping the Mayhem

ICROP classification:

• Zones (Location): Extent from optic disc.
  • Zone I: Posterior pole; radius 2x disc-macula distance. Poorest prognosis.
  • Zone II: Zone I edge to nasal ora serrata & temporal equator.
  • Zone III: Remaining anterior temporal crescent.
• Stages (Severity): Neovascularization degree.
  • Stage 1: Demarcation Line.
  • Stage 2: Ridge.
  • Stage 3: Ridge + extraretinal fibrovascular proliferation (mild/mod/sev).
  • Stage 4: Partial Retinal Detachment (RD) (4A: extrafoveal; 4B: foveal).
  • Stage 5: Total RD (funnel).
• Plus Disease ("+"): Vascular dilation & tortuosity (≥2 posterior quadrants). Active, severe ROP.

  ⭐ Plus disease is a critical indicator for treatment.

• AP-ROP (Aggressive Posterior ROP): Rapid, severe; Zone I/posterior Zone II. Prominent plus disease.
• Pre-Plus: Abnormal vessels, not yet Plus disease criteria met.

ROP: Screening Guidelines - Catching It Early

• Who to Screen:
  • Infants: Birth Weight (BW) < 1500g OR Gestational Age (GA) ≤ 32 weeks.
  • Selected infants: BW 1500-2000g or GA > 32 weeks with risk factors like prolonged oxygen therapy, sepsis, intraventricular hemorrhage, or significant cardiorespiratory compromise.
• When to Screen (First Exam):
  • Perform at 4 weeks chronological age (CA) OR 31 weeks post-conceptional age (PCA = GA + CA), whichever is later.
    • 📌 Mnemonic: "4-31 Rule".
  • Crucial for timely detection of treatable ROP.

⭐ Plus Disease: Marked by venous dilation and arteriolar tortuosity in at least two posterior pole quadrants. Its presence signifies severe ROP and often necessitates prompt treatment.

ROP: Management & Treatment - Saving Tiny Sight

• Goal: Prevent retinal detachment & blindness.

• Screening: Crucial for timely intervention.

• Treatment Criteria (ETROP Study):

  • Type 1 ROP: High-risk prethreshold ROP requiring treatment.
    • Zone I, any stage ROP with plus disease.
    • Zone I, stage 3 ROP, no plus disease.
    • Zone II, stage 2 or 3 ROP with plus disease.
  • Type 2 ROP: Lower risk, observe closely.

• Treatment Modalities:

  • Laser Photocoagulation: Ablate avascular retina. Standard of care.
    • Indication: Type 1 ROP.
    • Timing: Within 72 hours of diagnosis.
  • Anti-VEGF (Bevacizumab, Ranibizumab): Intravitreal injection.
    • Indication: Primarily for Zone I ROP (especially posterior/AP-ROP).
    • ⚠️ Potential for late recurrence; long-term systemic effects unclear.
  • Vitreoretinal Surgery: For retinal detachment (Stage 4 & 5).

• Complications of Treatment:

  • Laser: Myopia, astigmatism, cataract, visual field defects.
  • Anti-VEGF: Endophthalmitis (rare), ROP recurrence.

⭐ Bevacizumab is often preferred for aggressive posterior ROP (AP-ROP) due to its ability to rapidly control neovascularization.

• Follow-up: Lifelong, due to risks of strabismus, amblyopia, myopia, glaucoma, late detachment. 📌 ROP needs Regular Ophthalmic Patrol.

High‑Yield Points - ⚡ Biggest Takeaways

• ROP is a proliferative retinopathy in premature infants (<1500g, <32 weeks), linked to oxygen therapy.
• Key pathology: biphasic - initial vaso-cessation (hyperoxia), then vaso-proliferation (hypoxia).
• Screening starts at 4 weeks postnatal or 31 weeks postconceptional age.
• Plus disease (vascular dilation/tortuosity) indicates severe, active ROP.
• Laser photocoagulation is standard for Type 1 ROP; anti-VEGF is an option.
• Most common site: avascular temporal retinal periphery.
• Long-term risks: myopia, strabismus, retinal detachment.