Overview
Definition:
Retinopathy of prematurity (ROP) is a potentially blinding disorder of the developing retinal vasculature in premature infants
It is characterized by abnormal growth of blood vessels in the retina, which can lead to retinal detachment and vision impairment.
Epidemiology:
ROP affects approximately 15-30% of infants born before 28 weeks gestation
The incidence is inversely related to gestational age and birth weight
Factors like oxygen therapy, sepsis, and blood transfusions increase risk
In India, ROP is a significant cause of childhood blindness, with an estimated 15-20% of premature infants developing treatable ROP.
Clinical Significance:
ROP is the leading cause of preventable childhood blindness
Timely screening and treatment are crucial to prevent irreversible vision loss and ensure optimal visual development in preterm infants
Understanding the differences between anti-VEGF therapy and laser photocoagulation is vital for evidence-based management decisions in DNB and NEET SS preparation.
Clinical Presentation
Symptoms:
Often asymptomatic in early stages
Parents or caregivers may note strabismus
In advanced stages, signs of retinal detachment like poor fixation, nystagmus, or leukocoria may be observed
Significant visual impairment or blindness is the ultimate consequence if untreated.
Signs:
Ophthalmoscopic examination reveals abnormal, tortuous blood vessels extending beyond the vascular arcade
This is followed by neovascularization (NV) at the ridge between vascularized and avascular retina
In progressive disease, NV can lead to fibrous proliferation and tractional retinal detachment
"Plus disease" signifies dilated and tortuous blood vessels in the posterior pole.
Diagnostic Criteria:
ROP is staged based on the extent and severity of vascular changes
The International Classification of ROP includes: Stage 1 (demarcation line), Stage 2 (ridge), Stage 3 (ridge with extra-retinal neovascularization), Stage 4 (partial retinal detachment), and Stage 5 (total retinal detachment)
Zone 1 is the posterior pole, Zone 2 extends to the nasal periphery, and Zone 3 is the temporal periphery
"Urgent" treatment is indicated for Stage 3 ROP in Zone 1 or 2 with plus disease, or any ROP in Zone 1 with plus disease.
Diagnostic Approach
History Taking:
Detailed perinatal history is paramount: gestational age at birth, birth weight, duration of oxygen therapy and its concentration, presence of comorbidities (sepsis, apnea, necrotizing enterocolitis), and any blood transfusions
Family history of eye conditions is also relevant.
Physical Examination:
A comprehensive ophthalmic examination by a trained ophthalmologist using indirect ophthalmoscopy and scleral indentation is essential
This should be performed in a well-lit environment, typically under sedation for very premature infants
Regular follow-up examinations are scheduled based on the infant's risk factors and the presence of ROP.
Investigations:
No laboratory investigations are directly used to diagnose ROP
The diagnosis is solely based on direct visualization of the retinal vasculature via indirect ophthalmoscopy
Screening guidelines typically involve examinations at 4-6 weeks of age or when infants reach a corrected gestational age of 30-32 weeks, with frequency adjusted based on findings.
Differential Diagnosis:
Conditions mimicking ROP include familial exudative vitreoretinopathy, Coats' disease, persistent fetal vasculature (PFV), ocular toxocariasis, and congenital retinal fold
These can be differentiated by their characteristic clinical features, family history, and absence of the typical ROP vascular changes.
Management
Initial Management:
The primary goal is prevention through optimal neonatal care: controlled oxygen administration, management of sepsis and cardiorespiratory compromise, and avoidance of prolonged exposure to high oxygen concentrations
Nutritional support is also important.
Medical Management:
The main medical interventions are anti-VEGF agents (e.g., bevacizumab, ranibizumab)
These inhibit vascular endothelial growth factor (VEGF), which is crucial for aberrant neovascularization
Bevacizumab, though off-label, is widely used due to its cost-effectiveness and efficacy
It is injected intravitreally.
Surgical Management:
Laser photocoagulation, typically using a diode laser, is the traditional treatment
It ablates the avascular peripheral retina, reducing VEGF production and preventing further neovascularization and progression to retinal detachment
Cryotherapy is an alternative but less commonly used method.
Comparative Considerations:
Anti-VEGF therapy is associated with fewer immediate complications, better peripheral vision preservation, and less refractive error than laser
However, concerns exist regarding systemic absorption and long-term effects
Laser therapy is well-established and effective, but can lead to peripheral visual field defects and increased myopia
Current guidelines often recommend laser for posterior ROP and anti-VEGF for anterior ROP, or a combination
Treatment decisions depend on the stage, zone, presence of plus disease, and surgeon preference.
Complications
Early Complications:
Complications of treatment include infection (endophthalmitis), inflammation, transient intraocular pressure rise, cataract formation, and vitreous hemorrhage
Complications of untreated ROP include retinal detachment, strabismus, nystagmus, amblyopia, and severe visual impairment or blindness.
Late Complications:
Late sequelae of treated ROP, especially if treatment was delayed or incomplete, include staphyloma, retinal folds, myopia, strabismus, amblyopia, and persistent visual impairment
Long-term follow-up is critical to monitor for these late complications.
Prevention Strategies:
Optimal neonatal care to prevent prematurity and its complications is the first step
Rigorous screening protocols for all eligible premature infants ensure early detection
Prompt and appropriate treatment, whether laser or anti-VEGF, is key to preventing vision loss.
Prognosis
Factors Affecting Prognosis:
The stage and zone of ROP at diagnosis, presence of plus disease, promptness and adequacy of treatment, and infant's overall health status significantly influence prognosis
Treatment success rates are higher for less advanced stages.
Outcomes:
With timely and appropriate treatment, the majority of infants with ROP can achieve functional vision
However, some degree of visual impairment may persist, particularly in cases of advanced ROP or treatment failure
Recurrence of ROP or development of late complications can occur.
Follow Up:
Lifelong ophthalmological follow-up is recommended for all infants treated for ROP, or those who had significant ROP even without treatment
This allows for early detection and management of refractive errors, strabismus, amblyopia, and the potential development of late complications such as glaucoma or retinal detachment.
Key Points
Exam Focus:
Understand the staging and zone classification of ROP
Differentiate indications for laser vs
anti-VEGF therapy
Know the potential benefits and risks of each treatment modality
Recall screening guidelines and follow-up protocols
High-yield areas for DNB/NEET SS include complications of ROP and comparison of treatment outcomes.
Clinical Pearls:
Always consider ROP in any infant born prematurely, especially those with prolonged oxygen use or other significant morbidities
Early detection through regular screening is paramount
In many centers, intravitreal bevacizumab is now the preferred treatment for threshold ROP due to its efficacy and favorable side effect profile compared to laser, but this is context-dependent.
Common Mistakes:
Delaying screening or treatment initiation
Inadequate ophthalmic examination technique leading to missed diagnosis
Over-reliance on one treatment modality without considering the specific clinical context
Inadequate follow-up leading to unmanaged late complications
Not considering the specific ROP guidelines relevant to India.