Retinopathy of prematurity

Retinopathy of prematurity is a vascular-proliferative disorder of retina in preterm infants

Classification

Based on International Classification of ROP (ICROP)

Zones of ROP

Stages of ROP

Stage
5a - open funnel - optic disc visible under ophthalmoscopy
5b - closed funnel - optic disc not visible under ophthalmoscopy
5c - stage 5b + anterior chamber changes like uveitis, iridocorneolenticular adhesions

Plus disease

Severity Classification

Aggressive ROP

• developing rapidly from stage 1 to stage 5
• no typical progression of stages
• typically present in zone 1 or posterior zone 2

Screening of ROP

Parameters for consideration

• Birth weight
• Gestational age at birth

RBSK criteria for screening

• born at 34 weeks or less
• gestational age not know conclusively or birth weight below 2000 g
• born at 34–36 weeks + any of the following risk factors
  • need for respiratory support
  • oxygen therapy for more than 6 hours
  • sepsis
  • episodes of apnea
  • need for blood transfusion
  • need for exchange transfusion
• Admission into NICU/SNCU can be taken as a surrogate risk factor

AIIMS criteria for screening

• born at 32 weeks or less
• gestational age not know conclusively or birth weight below 1500 g
• born at 32–35 weeks + any of the following risk factors
  • need for respiratory support
  • oxygen therapy for more than 6 hours
  • sepsis
  • episodes of apnea
  • need for blood transfusion
  • need for exchange transfusion
• Admission into NICU/SNCU can be taken as a surrogate risk factor

How often to screen

• 32 weeks of PMA or 4 weeks of PNA whichever is later
• If born less than 28 weeks or birth weight less than 1200 g ROP to be done at 2-3 weeks of PNA

Follow up

• every 1–2 weeks depending upon the staging
• Screening can be stopped once vascularization is complete (around 40–44 weeks PMA) or if ROP shows regression

How to dilate

• Phenylephrine 2.5% + Tropicamide 0.5%, 2 times at 10 minute interval, 30 mins before examination

Treatment

Ablation of peripheral avascular retina thereby reducing the hypoxic drive of retina

Laser treatment

• should be done in NICU
• with double frequency YAG laser
• done in GA with cardiac monitor (in resource limited setting 2 mcg/kg bolus followed by 2 mcg/kg/hr of fentanyl can be an alternative)
• both eyes can be ablated in same setting
• followed after 5–7 days and thereafter weekly till signs of regression

Anti-VEGF Drugs

• Bevacizumab or Ranibizumab injection into vitreous chamber
• increased risk of reactivation as compared to laser therapy
• complications include
  • retinal detachment
  • persistent avascular retina
  • macular anomalies
  • glaucoma
  • vitreous hemorrhage

Vitreoretinal surgery

• For advanced ROP (stage 4 and 5)
• Stage 5 ROP carries a poor prognosis

Regression

2 types

• Spontaneous Regression
• Treatment induced regression
  • can be seen 1-3 days of Anti-VEGF and 7-14 days of laser therapy
  • rest of retina can vascularize normally or arrest of vascualrization (Persistent Avascular Retina-PAR) can occur

Reactivation

• common with monotherapy of Anti-VEGF; rare with laser therapy
• peripheral avascular retina remain viable and produce VEGF
• This causes reactivation after phase of regression
• occurs between 37-60 weeks PMA
• can be seen in original site or different site

Prevention

• Antenatal steroids - reduce RDS and IVH, both are known risk factors of ROP
• Delayed cord clamping - reduces need of blood transfusion
• Temperature regulation
• Gentle respiratory management

Interventions in neonatal unit - POINTS of care

• Pain Control - use of swaddling and oral sucrose
• Oxygen Management - maintain oxygen saturation between 91-95%
• Infection control
• Nutrition
• Temperature control
• Supportive care