A 12-week-old infant born at 28 weeks gestation with birth weight 1200 g presents for retinopathy of prematurity (ROP) screening. Fundoscopy reveals a demarcation ridge with extraretinal fibrovascular proliferation (marked **A** in the diagram), along with dilated and tortuous posterior pole vessels. The infant has not yet received treatment. According to the International Classification of ROP (ICROP3), which of the following best describes the stage and treatment indication for the structure marked **A**?

Question

Accepted Answer

D. Stage 3 ridge with extraretinal fibrovascular proliferation; intravitreal anti-VEGF therapy is preferred for this aggressive posterior disease. ## Why Stage 3 ridge with extraretinal fibrovascular proliferation; intravitreal anti-VEGF therapy is preferred for this aggressive posterior disease is right

The structure marked **A** (demarcation ridge with extraretinal fibrovascular proliferation) defines ICROP3 Stage 3 ROP. The presence of extraretinal fibrovascular tissue indicates active neovascularization driven by the biphasic pathogenesis: Phase 1 hyperoxia-induced vaso-obliteration followed by Phase 2 relative hypoxia triggering massive VEGF and IGF-1 release. Combined with dilated and tortuous posterior pole vessels (plus disease), this represents Type 1 ROP—the threshold for treatment. Intravitreal anti-VEGF agents (bevacizumab 0.625 mg or ranibizumab 0.2 mg) are now preferred for aggressive posterior disease (particularly zone I), as demonstrated by BEAT-ROP and RAINBOW trials, offering rapid plus-disease regression, peripheral visual field preservation, and avoidance of laser-induced myopia. [AAO BCSC Pediatric Ophthalmology 2024; ICROP3 classification]

## Why each distractor is wrong

- **Stage 2 ridge; laser photocoagulation of avascular retina is indicated**: Stage 2 is a ridge without extraretinal fibrovascular proliferation. The presence of extraretinal neovascular tufts at **A** defines Stage 3, not Stage 2. Laser is standard for zone II disease, not the aggressive posterior Stage 3 disease shown here.
- **Stage 1 demarcation line; observation alone is recommended**: Stage 1 is a demarcation line (flat boundary), not a ridge with fibrovascular proliferation. The structure at **A** clearly shows a ridge with extraretinal tufts, making it Stage 3. Observation is inappropriate for Type 1 ROP.
- **Stage 4 partial retinal detachment; vitrectomy is the definitive treatment**: Stage 4 involves retinal detachment, which is not present in this case. The demarcation ridge with fibrovascular proliferation is Stage 3. Vitrectomy is reserved for advanced tractional detachment (Stage 4–5), not Stage 3.

**High-Yield:** Stage 3 ROP with plus disease = Type 1 ROP = treat with anti-VEGF for posterior/aggressive disease, laser for zone II disease.

[cite: AAO BCSC Pediatric Ophthalmology 2024; ICROP3 classification; BEAT-ROP and RAINBOW trials]

Answer

A. Stage 1 demarcation line; observation alone is recommended

Answer

B. Stage 4 partial retinal detachment; vitrectomy is the definitive treatment

Answer

C. Stage 2 ridge; laser photocoagulation of avascular retina is indicated

Explanation

Why Stage 3 ridge with extraretinal fibrovascular proliferation; intravitreal anti-VEGF therapy is preferred for this aggressive posterior disease is right

Why each distractor is wrong

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