Optic Nerve Coloboma

Optic Nerve Coloboma
SYMPTOMS Decrease in vision, Visual field defects
May experience a further decrease in vision and/or metamorphopsia in the presence of macula involvement
SIGNS Typically bilateral
Large disc that is partially or completely excavated inferiorly with a glistening white appearance (superior rim is typically intact), Peripapillary pigmentary changes (Hypopigmentation present more so than hyperpigmentation), Possible macular involvement (Sensory retinal detachment at the macula, Choroidal neovascular membrane)
Optic nerve colobomas can be associated with Other ocular colobomas, Posterior lenticonus, Remnants of the hyaloid artery, Posterior embryotoxon
WORK-UP Pupils (presence of an APD if optic nerve coloboma is unilateral or asymmetric), EOMs, Cover test (strabismus may be present), Full eye exam with dilation, Visual field, OCT of the optic nerve, OCT of the macula (may present with a sensory retinal detachment at the macula or choroidal neovascular membrane), OCT-Angiography, Fundus Autofluorescence, Fluorescein Angiography, Indocyanine Green Angiography, Fundus photos, Electrodiagnostic testing (VEP), Watzke-Allen test, Macular photostress test, Amsler grid
TREATMENT Give take home Amsler grid in order to monitor for macula involvement
Optic nerve coloboma with no macular involvement: Monitor. No treatment is needed
Optic nerve coloboma with macular involvement (sensory retinal detachment at the macula or choroidal neovascular membrane): Refer to a retinal specialist ASAP for further evaluation and treatment (treatment is typically not successful due to the high rate of recurrence)
Refer patient to a pediatrician and pediatric neurologist as these patients commonly have neurologic and systemic abnormalities
If the patient has poor vision, refer to low vision
FOLLOW-UP If monitoring, the patient should be seen back in 6-12 months
After patient is evaluated and treated by a retinal specialist and the retina/macula is stable, the patient should be seen back every 6 months
ADDITIONAL LAB | TESTS Genetic testing: PAX2
Rule out the following syndromes that can be associated with optic nerve colobomas (30% of the time):CHARGE syndrome, Branchio-oculo-facial syndrome, First arch syndromes, Fraser syndrome, Amniotic band syndrome, Aicardi syndrome, Renal-coloboma syndrome
ETIOLOGY Developmental optic nerve dysplasia (occurs due to incomplete closure of the embryonic fissure)
Can be sporadic or autosomal dominant in terms of inheritance (mutation of the PAX2 gene)
DIFFERENTIAL DX Morning glory disc, Optic nerve pit, Posterior staphyloma
NOTES Optic nerve colobomas are usually an isolated anomaly
Optic nerve colobomas can be associated with myopia and/or strabismus
Optic nerve colobomas are typically located inferiorly and can also involve the retina and choroid