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SYMPTOMS
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Decrease in vision, Visual fields defects, Loss of depth perception
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SIGNS
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Typically bilateral (15-25% of cases are unilateral)
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Small optic disc that may appear pale or grey in color, Peripapillary double ring sign, Retinal vascular tortuosity with anomalous branching at the optic nerve (vasculature is large compared to the size of the optic disc)
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Optic nerve hypoplasia can be associated with Microphthalmos, Aniridia, Colobomas
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WORK-UP
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Pupils (presence of an APD if optic nerve hypoplasia is unilateral or asymmetric), EOMs (possible sensory nystagmus that develops in cases of bilateral optic nerve hypoplasia usually between 1 to 3 months of age), Cover test (strabismus, often an esotropia, may be present), Full eye exam with dilation, Visual field, OCT of the optic nerve (presence of RNFL thinning since there is a decreased number of axons), OCT of the macula (presence of GCL thinning since there is a decreased number of ganglion cells), Fundus photos, Electrodiagnostic testing (VEP: Abnormal), DD/DM: Measure the ratio of horizontal disc diameter (DD) to the distance between the macula and temporal edge of the disc (DM) (Greater than 0.35: Normal optic disc size / 0.30-0.35: Mild optic nerve hypoplasia with usually good vision / Less than 0.30: Moderate to severe optic nerve hypoplasia with usually poor vision)
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TREATMENT
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Monitor. No treatment is effective
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If the patient has poor vision, refer to low vision
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Refer patient to a pediatric endocrinologist and pediatric neurologist as these patients commonly have neurologic and hormonal abnormalities such as developmental delay, cerebral palsy, seizures, hypopitutitarism, hypothyroidism, and hypothalamic dysfunction. Treating these issues early is key to better quality of life.
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FOLLOW-UP
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Patient should be seen back in 12 months
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ADDITIONAL LAB | TESTS
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Testing will most likely be ordered by a pediatric endocrinologist or pediatric neurologist: MRI with and without contrast of the brain and orbits, Endocrinologic work-up
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ETIOLOGY
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Congenital nonprogressive underdeveloped optic nerve that may be associated with a young maternal age, premature birth, material diabetes, fetal alcohol syndrome, and use of recreational drugs, cigarettes, antidepressants, anticonvulsants, and quinine during pregnancy
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Optic nerve hypoplasia can also present as an isolated anomaly
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DIFFERENTIAL DX
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Optic atrophy, Optic nerve edema, Optic nerve drusen, Crowded optic disc, Optic nerve coloboma
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NOTES
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Optic nerve hypoplasia is the most common congenital optic nerve anomaly
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Vision associated with optic nerve hypoplasia can be anywhere from normal to no light perception and typically does not progress over time. Most patients see 20/200 or worse. There does not appear to be any direct correlation between the size of the optic disc and visual function.
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Optic nerve hypoplasia can be associated with high levels of astigmatism and/or myopia
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Neurologic conditions are more commonly associated with bilateral optic nerve hypoplasia than unilateral optic nerve hypoplasia
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De Morsier syndrome (Septo-optic dysplasia) is the most common neurological disease associated with optic nerve hypoplasia
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Topless disc syndrome (Superior segmental optic nerve hypoplasia): Hypoplasia of only the superior aspect of the optic nerve that is associated with a dense inferior visual field defect. Typically associated with maternal diabetes
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