Coloboma of optic nerve

Morning Glory syndrome
Classification and external resources
OMIM	120430

Coloboma of optic nerve or Morning Glory syndrome is a rare defect of the optic nerve that causes moderate to severe blindness. It is extremely rare, occurring in only one person per every two million in the United States.

Definition

Morning Glory syndrome is a congenital anomaly of the optic disc in which there is a funnel-shaped excavation of the posterior fundus incorporating the optic nerve, surrounded by an elevated annulus of chorioretinal pigment.^[1] The issue stems from an undeveloped optic nerve: while in utero, the nerve ending from the eye never reached the nerve ending from the brain. A central core of white glial tissue occupies the position of the normal optic cup, causing a white mass. When a picture is taken of the eye, this white mass stands out apart from the veins of the eyes, looking very much like the center of a Morning glory flower. Reflection from within the eye may give the appearance of a white pupil, due to the lack of the "black" optic nerve mass, although this "clouded pupil" cannot be used to diagnose the disease. Morning Glory Syndrome typically affects only one eye; but cases has been documented of bilateral Morning Glory Syndrome (those with that stage of severe blindness have other disorders as well, like autism^[2]). Also, this syndrome is different from an optic disk injury, as the disorder is present at birth and not developed later in life. Young girls are twice as likely to be diagnosed with this disorder, pointing toward the possibility of a genetic connection.

Effects

Vision in the affected eye is severely impaired, depending on the completed development of the optic nerve. More mild cases cause limited depth or color perception, while the most severe cause total blindness. Full use of the affected eye is never gained. The most common side effect of this disorder is eyestrain from overuse of the un-affected eye. Also, there is an increased risk of serious retinal detachment, manifesting in 1/3 of patients. If retinal detachment does occur, it is usually not correctable and all sight is lost in the affected eye.

Theories

The exact cause of this syndrome is unknown. This condition may be associated with brain and kidney disorders including papillorenal syndrome, a PAX2 gene mutation. Many times, this syndrome manifests itself alongside other midline or cranial disorders, but it does not seem to be caused by those disorders. Additionally, recent research points toward the possible connection between undiagnosed thyroid issues in the mother during the pregnancy and this syndrome. No conclusive evidence was found, however, due to the rare nature of this disease and its late appearance during childhood (negating the possibility of a neo-natal study).

It can be associated with PAX6.^[3]

Rarity

Morning Glory Syndrome is extremely rare. High-end guesses claim that this syndrome, first documented and diagnosed in the late 1970s, affects approximately one person out of every million in the United States. More conservative speculation place that number closer to one out of every two or three million. Unfortunately, no surveys have been completed to document the exact effect rate of this syndrome, and very few research articles have been published in the United States on the topic since its first discovery. Several French organizations claim to be knowledgeable on the topic, but the published research seems lacking even from them.

Diagnosis

The first noticeable signs of the syndrome usually do not appear until after the first twelve months of the child's life. The child usually has severe balance issues as he or she learns to sit or walk, often leaning or tilting the head toward the good eye to correct the brain's skewed perception of the world. Often the child will fall in the same direction while walking or run into objects that are placed on his or her blind side. The child will also develop a "lazy eye", or an eye that drifts severely away from the child's fixed point of reference. This syndrome must be confirmed through pupillary dilation and examination of the optic disk, as the signs alone will not constitute a diagnosis.

Children with Morning Glory live relatively normal lives, even those who have discolored or lazy pupils. Although non-prescription glasses should be worn for eye protection, this syndrome does not usually prevent the individual from living a normal life, driving cars, playing sports, reading, etc. Certain activities, such as gymnastics and ice skating, may be more difficult for patients with Morning Glory due to a compromised view of the world and skewed sense of balance, but they are still possible. Like most other eye conditions, a diagnosis of Morning Glory precludes a person from certain occupations, such as being a baseball player or fighter pilot.

See also

• Blindness
• Cataracts

References

1. ^ Definition of Morning Glory Syndrome from MedicineNet.com
2. ^ Nawratzki I, Schwartzenberg T, Zaubermann H, Yanko L (1985). "Bilateral morning glory syndrome with midline brain lesion in an autistic child". Metab Pediatr Syst Ophthalmol 8 (2-3): 35–6. PMID 3870943. 
3. ^ Azuma N, Yamaguchi Y, Handa H, et al. (June 2003). "Mutations of the PAX6 gene detected in patients with a variety of optic-nerve malformations". Am. J. Hum. Genet. 72 (6): 1565–70. doi:10.1086/375555. PMC 1180317. PMID 12721955. http://linkinghub.elsevier.com/retrieve/pii/S0002-9297(07)60456-X.