Overview

Definition:
-Retinopathy of Prematurity (ROP) is a potentially blinding disorder of the developing retinal vasculature in premature infants
-Post-discharge screening is crucial to detect and manage ROP that may develop or progress after the infant leaves the neonatal intensive care unit (NICU).
Epidemiology:
-ROP affects approximately 15-30% of very low birth weight (VLBW) infants
-Incidence varies with gestational age and birth weight
-infants born before 30 weeks gestation and/or weighing less than 1500g are at highest risk
-Post-discharge progression or new-onset ROP can occur in up to 15-20% of screened infants.
Clinical Significance:
-Untreated ROP can lead to retinal detachment, strabismus, myopia, and severe visual impairment or blindness
-Timely post-discharge screening and intervention are paramount to prevent these long-term visual deficits and ensure optimal visual development in at-risk infants.

Risk Factors

Gestational Age: Infants born at < 30 weeks gestation are at highest risk.
Birth Weight: Infants weighing < 1500 grams at birth have increased risk.
Neonatal Course: Prolonged oxygen therapy, sepsis, intraventricular hemorrhage (IVH), necrotizing enterocolitis (NEC), and blood transfusions are associated with higher ROP incidence.
Genetic Factors: Some genetic predispositions may influence ROP development.
Ethnicity: While less emphasized, some studies suggest ethnic variations in ROP prevalence.

Diagnostic Approach

History Taking:
-Detailed review of neonatal course, including gestational age, birth weight, duration of oxygen therapy, need for blood transfusions, and presence of other significant morbidities
-Family history of eye conditions may also be relevant.
Physical Examination:
-A comprehensive eye examination by a trained ophthalmologist is required
-This involves indirect ophthalmoscopy or slit-lamp biomicroscopy using a wide-field lens to visualize the peripheral retina
-Routine pediatric physical examination should be performed to assess overall health.
Investigations:
-The primary investigation is a dilated fundus examination
-No laboratory tests or imaging modalities are routinely used for diagnosis of ROP itself, but investigations for associated neonatal conditions may be relevant.
Staging Rop:
-ROP is staged based on the severity and extent of vascular abnormalities
-The International Classification of ROP (ICOP) system categorizes ROP into zones, stages (Stage 1: demarcation line, Stage 2: elevated ridge, Stage 3: retinal-retinal pigment epithelial detachment, Stage 4: partial retinal detachment, Stage 5: total retinal detachment), and the presence of plus disease (engorged, tortuous retinal vessels)
-Zone I is the most posterior and dangerous.
Diagnostic Criteria: The diagnosis is made via ophthalmoscopic findings, categorizing the disease based on the ICOP system and identifying "plus disease," which indicates more aggressive ROP and requires urgent treatment.

Screening Timing And Referrals

Initial Screening: The first eye examination should ideally occur between 4-6 weeks of corrected gestational age (CGA) or 31 weeks post-menstrual age (PMA), whichever is earlier, for infants at high risk (gestational age < 30 weeks or birth weight < 1500g).
Post Discharge Screening Schedule:
-For infants discharged before their initial screening is due, arrangements must be made for the examination to occur as scheduled
-If ROP is detected or if there is concern for progression, follow-up examinations are typically performed every 1-3 weeks, depending on the severity and stage of ROP, and response to treatment.
Referral Criteria:
-Referral for treatment is indicated for premature infants with: Stage 3 ROP in Zone I or II with or without plus disease
-Zone II ROP with significant plus disease
-or any infant with plus disease and encroaching vascularization into the avascular retina
-Prematurity alone is not an indication for treatment, but for screening.
Referral Mechanism:
-When ROP is detected that requires treatment, the neonatologist or pediatrician must ensure prompt referral to a pediatric ophthalmologist or ROP specialist equipped to provide laser photocoagulation or anti-VEGF therapy
-This referral should happen before discharge if possible, or immediately upon identification of concerning findings.

Management

Indications For Treatment: Treatment is indicated for threshold ROP, defined as Stage 3 ROP in Zone I or II with plus disease, or Stage 3 ROP in Zone II without plus disease that extends to Zone II, or rapidly progressing ROP.
Treatment Modalities:
-Laser photocoagulation (indirect diode laser) is the gold standard for threshold ROP
-Cryotherapy may be used in select cases
-Intravitreal anti-VEGF agents (e.g., bevacizumab, ranibizumab) are increasingly used, particularly for posterior ROP, but have established protocols and are often used in conjunction with laser.
Surgical Management: Vitrectomy or scleral buckling is reserved for advanced ROP (Stage 4 or 5) with retinal detachment, when laser or anti-VEGF therapy has failed or is not feasible.
Supportive Care:
-Optimizing the infant's overall health is crucial
-This includes ensuring adequate nutrition, managing respiratory support, and treating any systemic infections or complications
-Close monitoring of weight gain and oxygen saturation is important
-Gentle handling and minimizing light exposure for infants with active ROP may also be considered.

Complications

Early Complications: Retinal detachment, vitreous hemorrhage, lens opacities (from treatment), iris atrophy, neovascular glaucoma.
Late Complications: Strabismus (esotropia, exotropia), refractive errors (high myopia, astigmatism), amblyopia, glaucoma, retinal folds, macular dysfunction, and potential for permanent visual impairment or blindness.
Prevention Strategies: Strict adherence to screening guidelines, timely referral for treatment of threshold ROP, appropriate use of oxygen therapy, and management of underlying neonatal morbidities are key to preventing severe ROP and its complications.

Prognosis

Factors Affecting Prognosis:
-The prognosis depends on the stage and zone of ROP at diagnosis, the presence of plus disease, the response to treatment, and the overall health of the infant
-Early detection and treatment significantly improve outcomes.
Outcomes:
-With timely intervention, many infants achieve good visual outcomes, although residual refractive errors and mild visual deficits may persist
-Severe visual impairment or blindness is more common in infants with untreated or advanced ROP.
Follow Up:
-Infants treated for ROP require long-term follow-up by a pediatric ophthalmologist, often into childhood and adolescence, to monitor for refractive errors, strabismus, amblyopia, and the development of late complications like glaucoma or retinal detachment
-This follow-up is critical for maximizing visual potential.

Key Points

Exam Focus:
-Understand the definition, incidence, and risk factors for ROP
-Crucially, memorize the screening schedule (gestational age, birth weight thresholds) and criteria for referral for treatment (Stage 3, Zone I/II, plus disease)
-Be familiar with treatment modalities (laser, anti-VEGF, surgery) and their indications.
Clinical Pearls:
-Always consider ROP in premature infants, especially those with a complicated neonatal course
-Coordinate closely with ophthalmology for timely screening and management
-Post-discharge follow-up is non-negotiable for at-risk infants.
Common Mistakes:
-Missing the first screening exam post-discharge
-Delaying referral for threshold ROP
-Inadequate follow-up of treated or post-threshold ROP patients
-Not considering ROP in infants who were not in NICU for a prolonged period but were extremely premature.