Pediatric Ophthalmology

148 8 Congenital Abnormalities of the Optic Nerve

MORNING GLORY DISC ANOMALY ● Morning glory disc anomaly (MGDA) is a rare, congenital, usually unilateral, funnel-like excavation of the posterior fundus that incor porates the optic disc. ● The name derives from the similarity to the morning glory flower. ● More common in females and rare in Afri can Americans Etiology ● The embryologic basis of MGDA is unclear. A defect in fetal fissure closure or a primary mesenchymal abnormality has been hypothe sized as embryonic origins of MGDA. Symptoms ● Visual acuity is usually poor, with only one-third achieving 20/40 or better. Signs ● Strabismus ● Leukocoria ● Amblyopia ● Myopia ● Afferent pupil defect may be present. ● The optic disc is markedly enlarged, orange or pink in color, with a surrounding annular ring of pigmented uveal tissues. Retinal ves sels increased in number emanate radially from the disc, a central white tuft of glial tissue. Macula may be incorporated into the excavation (macular capture) ( Fig. 8-2 ). ● Serous retinal detachment (RD) in one-third of patients ● Optic nerve calcifications and microphthal mos may be associated. ● Associated systemic conditions may in clude the following:

■ Transsphenoidal basal encephalocele as sociated with midfacial anomalies (hyper telorism, flat nasal bridge, midline notch in the upper lip, and sometimes a midline cleft in the soft palate) ■ Midline or other brain abnormalities (e.g., agenesis of the corpus callosum, pitu itary abnormalities) ■ Ipsilateral abnormalities of the carotid circulation such as stenosis or aplasia of the carotid arteries with or without Moyamoya syndrome (progressive stenosis of the ter minal portion of the internal carotid artery and its main branches) ■ Associated with ipsilateral orofacial hemangioma—this association may fall within the spectrum of the PHACE syn drome ( p osterior fossa malformation, large facial h emangioma, a rterial anomalies, c ar diac anomalies and aortic coarctation, and e ye anomalies). ■ Neurofibromatosis type 2 ■ MGDA has been described as part of the spectrum of papillorenal syndrome (PRN). Patients with PRN have renal hy poplasia and optic nerve dysplasia. Optic nerve malformations are similar to colo boma but share features of optic pit and MGDA. Renal pathology can lead to renal failure. Mutations in PAX2 cause the PRN and are autosomal dominant. Hearing loss can be present in 10% of patients (PAX2 is also involved in cochlear development). Differential Diagnosis

● Optic nerve coloboma ● Peripapillary staphyloma Diagnostic Evaluation

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● MRI and magnetic resonance angiography should be obtained to rule out brain and vas cular abnormalities.

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