Morning glory disc anomaly

A six-month-old boy was referred to our hospital with strabismus. There were no cranial facial abnormalities and the neurological examination did not reveal pathological findings.

A Magnetic Resonance Imaging (MRI) was performed. T2- weighted images and FLAIR images revealed a left pipe-shaped optic disc with rise of the adjacent retinal surface and discontinuity of the uveoscleral surface. Abnormal tissue related to the distal segment of the affected optic nerve and elimination of the subarachnoid space were also demonstrated. T1-weighted images depicted hyperintense tissue within the elevated region of the retinal surface. The presence of fat within the optic nerve sheath was not identified. Gadolinium-enhanced images revealed enhancement of the displaced choroidal tissue related to the left optic nerve.

Morning glory disc anomaly ( MGDA) is a unilateral, congenital pipe-shaped projection of the posterior globe, that encloses the optic disc and owes its name to the resemblance to the morning glory flower[1]. It is crucial to differentiate this entity from optic nerve coloboma which is associated with more severe pathological entities [2]. Patients with MGDA are often referred early in their life with strabismus, poor vision or leucocoria. MGDA is supposed to result from a fault in the formation of the posterior sclera and the normal fusion. In this pathologic condition the optic disc, peripapillary retina, lamina cribrosa and choroid herniate posteriorly [3].

Although the diagnosis is clinically made, MR imaging provides findings suggestive of MGDA. A pipe-shaped posterior optic disc can be seen, accompanied by rise of the adjacent retinal surface and fluffy tissue lying within the optic cup, probably representing remnants of the hyaloid system [1,3,4]. It is postulated that the posterior sclera wall has failed to close, so that neural (glial tuft) elements extend into the enlarged, pipe-shaped optic disc. The elevated peripapillary tissue annulus appears hyperintense on T1-weighted images [3, 4]. Abnormal displaced choroidal tissue related to the distal segment of the affected optic nerve shows enhancement on gadolinium-enhanced images and is also accompanied by elimination of subarachnoid spaces [3]. The uveoscleral coat is interrupted and this is depicted as loss of integrity of the normal hypointense annulus on T2-weighted images and the ring of enhancement on contrast enhanced images. Fatty tissue in the distal optic nerve sheath can also be seen [4]. Patients with MGDA usually develop retinal detachments of the serous type [2, 4], due to the presence of small gaps occurring during contractions of the glial tuft. These small openings allow the accumulation of subretinal fluid and are thought to be responsible for retinal detachment. MGDA can be associated with facial abnormalities (microphthalmos, cleft palate, cleft lip, hypertelorism), central nervous system abnormalities (basal encephalocele, agenesis of corpus callosum), endocrine abnormalities, carotid stenosis or aplasia, Moyamaya disease and facial capillary haemangiomas [2, 5]. The coexistence of the above mentioned anomalies is possibly the result of failure of migration of neural crest cells of the midline craniofacial structures, secondary to faulty fetal cleft closure [4].

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