Inclusion criteria:  All term infants undergoing therapeutic hypothermia for hypoxic ischaemic encephalopathy (HIE). All preterm infants born at <29 weeks gestational age.  Specifically, all children fulfilling these criteria will be eligible. Evidence of hypo-accommodation is not required.  Exclusion criteria:  Infants that are still an inpatient at 8 weeks corrected gestational age. Ocular exclusion criteria: children with unrelated congenital or developmental ocular abnormality such as cataract requiring surgery, genetic retinal disease, coloboma. Retinopathy of prematurity will not be an exclusion criterion. Infants with high refractive error (more than -6.00D spherical equivalent or +8.00D spherical equivalent).