Discussion: Coloboma is the name given to a fissure or discontinuity in any ocular structure; the most typical form is that resulting from failure of the choroidal fissure to close properly. Colobomas are fairly common, often bilateral, and are usually mild; as a result, imaging studies of most patients with colobomas are normal. Two variants of colobomas have rather typical imaging findings. The morning glory syndrome (named for its characteristic ophthalmoscopic appearance) is a coloboma that affects the optic nerve at the optic disc; the syndrome is commonly associated with brain anomalies such as callosal agenesis and basilar encephaloceles. Imaging studies have a charateristic appearance in which the optic nerve head is displaced posteriorly. The displaced portion may be rectangular or cone-shaped. Contiguous retrobilbar cysts may be present. The other typical variant is known as coloboma with cyst (aka microphthalmia with cyst)and is a malformation caused by extensive proliferation of the embryonic retina with consequent separation of the inner and outer layers. Imaging studies will often demonstrate continuity of teh globe and the retrobulbar cyst, confirming the diagnosis and aiding differentiation from other conditions.
Handmann first described morning glory disc anomaly in 1929. However, the name morning glory disc anomaly was not given to this entity until 1970, when Kindler published his findings of an abnormal optic nerve appearance in 10 patients. His definition of morning glory disc anomaly was:
- An enlarged optic disc
- A funnel-shaped, excavated peripapillary region surrounded by a wide elevated annulus of chorioretinal pigment disturbance
- Central overlying white, fluffy tissue
- Retinal vessels appearing at the edge of the disc as multiple narrow branches.
Since this description, many reports of this disease have appeared in the literature. It has been associated with a number of anomalies including cleft lip and palate, basal encephalocele, neurofibromatosis type 2, absent corpus callosum, moyamoya disease (as in this case), retinal arteriovenous communication, renal abnormalities, and endocrine abnormalities. Morning glory disc anomaly is typically unilateral and occurs equally among men and women. The prevalence and incidence of this disorder is unknown. Patients typically present in childhood because of strabismus, poor vision, or leukocoria. The eye with morning glory disc anomaly will usually have poor vision (90% with 20/200 or worse) on the basis of either amblyopia or retinal detachment. However, patients will occasionally have good vision in the affected eye. | |