Paediatrics: Retinopathy of prematurity

Retinopathy of prematurity

Retinopathy of prematurity (ROP) is a leading cause of preventable blindness. Infants born <32/40 and those weighing <1500g at birth are at greatest risk. The incidence is decreasing and recent data sug-gest that around 90% of infants born weighing >1000g will have no ROP, however, this number drops to only 38% for those <750g at birth. The cause is multifactorial. In utero, the retinal vasculature develops in a rela-tively hypoxic environment, with vessels stimulated to grow towards the most hypoxic regions. This development is disrupted with preterm deliv-ery. ROP is associated with retinal arterial hyperoxic vasoconstriction and retinal ischaemia during retinal development before 32wks gestation. It is therefore, essential to monitor and prevent hyperoxia in infants requiring supplemental O₂. Minimizing variability in oxygenation may also be impor-tant.

Classification

ROP is a proliferative retinopathy that is classified according to interna-tionally accepted guidelines.

Screening criteria

•   27/40: first screen at 30–31/40 CGA.

•   27–32/40: first screen at day 28–35 of life.

•   Screen 2wkly thereafter unless:

any stage 3 disease;

any plus/pre-plus disease;

vessels end in zone 1, or posterior zone 2;

weekly screening if present.

•   Screening is performed by indirect ophthalmoscopy after pharmacological pupil dilatation or increasingly by wide field digital retinal imaging.

•   Screening continues until vascularization has progressed into zone 3 (usually >36/40).

Treatment

Diode laser treatment within 72hr (48hr if aggressive disease) of meeting any of the treatment criteria.

Babies should be ventilated, adequately sedated, and given a muscle relaxant. Atropine should be available.

Side effects of treatment include:

•   Need for re-ventilation.

•   Bradycardia.

•   Apnoea.

•   Ocular haemorrhage.

•   Eyelid trauma.

•   Laser burns.

Infants should be re-examined 5–7 days following treatment, and if no regression, re-treatment should be performed at 10–14 days after initial therapy. Steroid eye drops may be useful in decreasing post-operative swelling. Direct injections of monoclonal antibodies against vascular endothelial growth factor (VEGF) are showing promise as an alternative.

Prognosis

Almost all cases can be treated effectively so blindness is a rare outcome. There may be reduced visual fields in severe cases. Refractive errors are common.