Morning Glory Disc Anomaly

A congenital optic disc anomaly characterized by a funnel shaped excavation of the posterior fundus that incorporates the optic disc. Clinically, the optic disc malformation resembles the morning glory flower. Morning glory disc anomaly (MGDA) is usually unilateral and often results in a decrease in best-corrected visual acuity (BCVA). MGDA can be isolated or associated with other ocular or non-ocular anomalies.

Epidemiology

The overall prevalence of MGDA is unknown, but it is estimated at 1/38,500 among subjects between 2 and 19 years old in Sweden. More than 100 cases have been reported in the medical literature. The disease is thought to be more common in women than in men.

Clinical description

MGDA often manifests early in childhood with strabismus of the affected eye. When the child is older and BCVA can be assessed, a substantial visual loss is noted (BCVA usually ranging between counting fingers and 20/200 in the affected eye). However, visual acuity is not always severely impaired, and can be close to normal. MGDA can be isolated or associated with other ocular anomalies in the same or contralateral eye (nystagmus, cataract, microphthalmia, glaucoma, coloboma of the crystalline lens, optic nerve drusen, aniridia, lid haemangioma, preretinal gliosis, peripheral retinal non-perfusion, serous retinal detachment, lenticonus, glioma or cyst of any optic pathway, acute retrobulbar optic neuritis, etc.). In younger patients, MGDA combined with persistent hyperplastic primary vitreous may indicate higher incidence of, and more severe associated complications. Associated facial dysmorphism (hypertelorism, dysplastic ears, cleft lip and palate, etc.), intracranial anomalies (basal encephalocele, other types of encephalocele, affected pituitary gland, corpus callosum agenesis, cerebral midline lipomas, etc.) and renal abnormalities (renal hypoplasia, chronic glomerulonephritis, hydronephrosis, etc.) have been reported, as well as several neurovascular and cardiac defects. MGDA can be associated with Moyamoya disease, PHACES syndrome, Aicardi syndrome, neurofibromatosis type 2, Arnold-Chiari malformation type I, CHARGE syndrome, Poland syndrome, among others. Bilateral cases are rare and might be correlated with a more severe systemic involvement.

Etiology

The exact etiology is not fully understood, but the syndrome is related to poor development of the posterior sclera and lamina cribrosa during gestation. The PAX6 gene could be linked to the anomaly.

Diagnostic methods

The diagnosis is based on clinical examination and relies on fundoscopy findings, showing an enlarged optic disc with peripapillary pigmentations, funnel shaped deep excavation, a radiating pattern of retinal blood vessels and a pale fluffy tuft of hyperplastic glial tissue overlying the optic disc. Optical coherence tomography, OCT may show a serous retinal detachment. Other MGDA-associated ocular anomalies, disorders elsewhere, e.g. cerebral malformations, systemic involvement and diseases, etc. should be ruled out.

Differential diagnosis

The differential diagnoses include optic disc colobomas, staphylomas and amblyopia.

Management and treatment

There is no curative treatment for the anomaly. However, associated amblyopia is usually treated by occlusion of the contralateral eye with good possibilities of some visual improvement. Strabismus can be corrected with surgery. Serous retinal detachment seems common, usually not requiring treatment but needing follow up. Vitrectomy with peripapillary photocoagulation and silicone oil tamponade may be required if a proliferative retinal detachment is associated with macular hole in children with MGDA. Associated somatic disorders/conditions, especially cranial malformations, cerebrovascular anomalies, cardiovascular anomalies, renal anomalies, endocrine and other systemic disease, etc. should be diagnosed and, if possible, treated accordingly.

Prognosis

The visual loss is usually non-progressive but MGDA increases the risk of serous retinal detachment (30% of patients in some studies). Other reported complications include choroidal neovascularization.