What are the guidelines for clinical examination of retinopathy of prematurity using fundus examination?

Retinopathy of Prematurity: Clinical Fundus Examination Guidelines

Fundus examination for retinopathy of prematurity (ROP) must be performed by an ophthalmologist skilled in evaluating the preterm infant retina using indirect ophthalmoscopy through dilated pupils, with systematic documentation of zone, stage, extent, and plus disease. 1

Patient Selection for Screening

Infants requiring ROP screening include:

• Birth weight <1500g 2
• Gestational age <32 weeks 2
• Infants with these characteristics should undergo systematic dilated fundus examination 2

Timing and Technique of Examination

Essential Examination Method

• Indirect ophthalmoscopy is the primary examination technique for ROP screening 1, 2
• Examination must be performed through fully dilated pupils to visualize the peripheral retina 2
• The examiner must be an ophthalmologist specifically skilled in preterm infant retinal evaluation 1

Examination Components

The fundus examination should systematically document:

Zone Classification (anteroposterior extent):

• Zone I: Central retina (most posterior)
• Zone II: Mid-peripheral retina
• Zone III: Far peripheral retina 2

Stage Classification:

• Stage 1 through Stage 5 based on severity 2
• Document the clock hours (30° sectors) of involvement 2

Plus Disease Assessment:

• Evaluate for dilation and tortuosity of retinal blood vessels in the posterior pole 2
• Plus disease represents a major risk factor for rapid unfavorable progression requiring treatment 2

Additional Examination Findings in Preterm Infants

Common Non-ROP Fundus Features

In preterm infants without ROP, expect:

• Small cup-to-disc ratio 3
• Pigmented ring around the optic disc 3
• Hypopigmented fundus 3
• Greenish-gray color in peripheral vascularized retina 3
• Persistent primary vitreous remnant (8.2% of cases) 3
• Retinal hemorrhage (5.6% of cases) 3

Macular Development Assessment

• Document macular development stage during examination 3
• Macular maturation correlates with gestational age advancement 3

Advanced Imaging Considerations

Fundus Photography

• Fundus photography (RetCam) documents disease activity and severity 1
• Useful for tracking progression over time 4
• Provides objective documentation of vascular sheathing patterns and caliber changes 4

Fluorescein Angiography (FFA)

While not required for routine screening, FFA may be valuable in specific situations:

• Identifies delayed retinal arterial perfusion (predictor of progression) 5
• Detects "popcorn lesions" (predictor of progression) 5
• Visualizes features better than indirect ophthalmoscopy alone, particularly after anti-VEGF treatment 6
• Shows intense leakage in stage 3 ROP requiring treatment 5
• Ultra-wide-field FFA improves peripheral retinal vasculature visualization 6

Follow-Up Protocol

Frequency of Examinations

• Regular fundus examinations must continue until complete retinal vascularization occurs 2
• Examination schedule is guided by risk factors and initial findings 2
• More frequent monitoring required for infants with plus disease or advancing stage 2

Treatment Indications

Examination findings requiring treatment:

• Threshold disease 2
• Type 1 pre-threshold disease 2
• Stage 3 ROP with intense leakage on FFA (if performed) 5

Critical Pitfalls to Avoid

• Do not rely solely on algorithms (e.g., WINROP) for infants <31 weeks gestation or <1250g, as sensitivity is only 57.1% in this population; direct fundus examination remains necessary 7
• Do not use non-mydriatic cameras or undilated examination as the sole screening method, as peripheral retinal visualization is inadequate 1
• Do not delay examination in high-risk infants, as the majority will spontaneously regress but 9-14% of treated eyes still have unfavorable outcomes despite intervention 2
• Do not discontinue follow-up prematurely—continue examinations until complete peripheral retinal vascularization is confirmed, regardless of treatment status 2