Fig. 3.

A Coronal T2-weighted image showing the typical target-like appearance of the optic nerve-meningeal sheet complex with the dark optic nerve in the center surrounded by hyperintense perineural cerebrospinal fluid externally lined by the thin dark dural meningeal layer (arrowheads). A diameter greater than 5–6 mm (according to age below or above 1 year) suggests enlargement of the cerebrospinal fluid space due to intracranial hypertension. On the contrary, an optic nerve diameter smaller than 3 mm suggests optic nerve atrophy or hypoplasia. B Coronal T2-weighted image of the right orbit showing a thin superior rectus muscle consistent with severe hypotrophy