Ocular Abnormality in a 7-Day-Old Child

Scott C. Cardone, MD; Kimberly Yen, MDSeries Editor: David K. Coats, MD

Disclosures

August 16, 2005

Discussion

Optic nerve aplasia is a very rare condition that is characterized by absence of the optic nerve head on clinical examination and absence of the optic nerve and chiasm on MRI scan. Histologically, there is absence of the optic nerve, retinal ganglion cells, nerve fiber layer, and optic nerve vessels. Optic nerve aplasia is thought to be part of a spectrum of optic nerve hypoplasia, and prior to a clear definition of this disorder in the literature, many early reports of optic nerve aplasia were included in discussions of optic nerve hypoplasia.[1]

Aplastic optic nerves may be unilateral or bilateral. Bilateral cases are more often associated with other, major congenital defects that often result in death of the infant. For example, these patients can also have septo-optic dysplasia, a rare congenital birth defect similar to optic nerve hypoplasia.[2] Still, despite the frequency of such systemic abnormalities, bilateral aplasia of the optic nerves has also been reported in otherwise healthy children.[3]

Microphthalmia has been reported to occur with optic nerve aplasia, similar to our patient.[2,3,4] In addition, optic nerve aplasia has been associated with retinal pigment epithelial and choroidal colobomas, persistent fetal vasculature, and retinal dysplasia. There have been reports of posterior segment neovascularization, thought to be a response to the ischemia resulting from the absence of retinal vasculature.[5] Histologic evidence of neovascularization has been shown originating from the choroid through an area of retinochoroidal disorganization in a patient with optic nerve aplasia.[6]

The exact etiology of optic nerve aplasia is not known. However, authors have suggested that a defect in the formation of the embryonal fissure, failure of the hyaloid system to develop within the fissure, or primary agenesis of the retinal ganglion cells may be responsible.[6]

Treatment for this condition consists of evaluation to rule out associated CNS/endocrine abnormalities and supportive care for abnormalities identified.

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