• timing
• cup
• optic disc
• periventricular leucomalacia

Periventricular leucomalacia is an end stage lesion that results from hypoxic-ischaemic injury to the white matter of the developing brain.¹ This condition occurs in 32% of premature infants¹ and is believed to develop between the 24th and 34th weeks of gestation.² Periventricular leucomalacia most commonly involves the optic radiations adjacent to the trigone of the lateral ventricle, and the anterior corticospinal fibres adjacent to the intraventricular foramen.² Clinically, it can produce decreased visual acuity, inferior visual field constriction, visual cognitive impairment, ocular motility disturbances, and spastic diplegia.^2,3

The association of periventricular leucomalacia with optic nerve hypoplasia presents a complex diagnostic challenge for the ophthalmologist. In 1995, Jacobson et al recognised that periventricular leucomalacia produces a unique form of bilateral optic nerve hypoplasia characterised by an abnormally large optic cup and a thin neuroretinal rim contained within a normal sized optic disc.⁴ They attributed this morphology to prenatal injury to the optic radiations, with retrograde transsynaptic degeneration of retinogeniculate axons after the scleral canals had established normal diameters.⁴ The large optic cups can simulate glaucoma but the history of prematurity, normal intraocular pressure, and characteristic symmetrical inferior visual field defects all serve to distinguish periventricular leucomalacia (PVL) from glaucomatous optic atrophy.⁵ Whether the pseudoglaucomatous cupping of PVL warrants classification as a segmental form of optic nerve hypoplasia or a congenital optic …