Pediatrics

Optic nerve hypoplasia

OVERVIEW: What every practitioner needs to know

Are you sure your patient has optic nerve hypoplasia? What are the typical findings for this disease?

Findings that suggest optic nerve hypoplasia are:

1) Poor fixation one or both eyes

2) Nystagmus

3) Strabismus

4) Sluggish pupil response.

Each of these findings may be due to other causes, but optic nerve hypoplasia must be ruled out.

What other disease/condition shares some of these symptoms?

1. Congenital Motor Nystagmus

2. Retinal Dystrophies with poor vision

3. Other congenital optic nerve anomalies: coloboma, "morning glory" anomaly, optic nerve atrophy, optic disc swelling

What caused this disease to develop at this time?

Developmental anomaly of optic nerve in utero. Decrease number of axons and supporting structures in optic nerve head due to insult or developmental defect in 1st or 2nd trimester.

Related conditions include prenatal exposure to alcohol, maternal diabetes, young primiparae.

What laboratory studies should you request to help confirm the diagnosis? How should you interpret the results?

Endocrine evaluation for hypopituitarism if structural anomalies on magnetic resonance imaging (MRI). Anomalies of growth hormone (64%), hyperprolactinemia (48%), hypothyroidism (35%), Adrenal insufficiency (17%), Diabetes Insipidus (4%) with pituitary abnormalities.

Would imaging studies be helpful? If so, which ones?

MRI to rule out pituitary anomaly, absent septum pellucidum, absent corpus callosum, encephalomalacia, leukomalacia, schizencephaly in up to 60% of patients.

Confirming the diagnosis

Diagnosis by ophthalmic exam of optic nerve with direct or indirect ophthalmoscopy.

Optic nerve hypoplasia is considered in a small optic nerve head with the distance between the center of the disc and fovea is greater than 3 disc diameters. Associated findings include a double ring sign (small optic nerve with peripapillary pigmented or non-pigmented ring), vessel tortuosity and a blunt foveal reflex.

If you are able to confirm that the patient has optic nerve hypoplasia, what treatment should be initiated?

  • Ophthalmologic evaluation. Visual prognosis is guarded but patients have varying degrees of visual function.

  • Low vision evaluation if deemed needed by ophthalmologist.

  • Treatment of endocrine abnormalities based on MRI findings.

  • Neurologic evaluation based on MRI findings.

What are the adverse effects associated with each treatment option?

N/A

What are the possible outcomes of optic nerve hypoplasia?

Visual prognosis guarded but children have varying degrees of visual impairment. Low vision assistance offers a good functional prognosis assuming no neuro-developmental issues. The visual prognosis is stable condition lifelong.

What causes this disease and how frequent is it?

Optic nerve hypoplasia varies in severity and is not uncommon. Boys are affected more commonly than girls. It is unilateral 20% of the time. Central nervous system anomalies are present in up to 60% of cases. These CNS anomalies are present in unilateral or bilateral cases. Endocrine abnormalities have been reported in 6% to 70% of patients.

The three genes, HESX1, OTX2, and SOX2, all play important roles in embryonic development. These may play a role in optic nerve hypoplasia.

How do these pathogens/genes/exposures cause the disease?

N/A

Other clinical manifestations that might help with diagnosis and management

N/A

What complications might you expect from the disease or treatment of the disease?

Hypopituitarism

Legal blindness

Are additional laboratory studies available; even some that are not widely available?

N/A

How can optic nerve hypoplasia be prevented?

Avoidance of excessive alcohol use during pregnancy.

What is the evidence?

Ahmad, T, Garcia-Filion, P, Borchet, M. "Endocrinological and auxological abnormalities in young children with optic nerve hypoplasia: A prospective study". J Pediatr. vol. 148. 2006. pp. 78-84.

Garcia, ML, Ty, EB, Taban, M. "Systemic and ocula findings in 100 patients with optic nerve hypoplasia". J Child Neurol. vol. 21. 2006. pp. 949-956.

Hellstrom, A, Wiklund, LM, Svensson, E. "The clinical and morphologic spectrum of optic nerve hypoplasia". JAAPOS. vol. 29. 1999. pp. 212-220.

Walton, DS, Robb, RM. "Optic nerve hypoplasia: A report of 20 cases". Arch Ophthalmol. vol. 84. 1970. pp. 572.

Garcia-Filion, P, Eppport, K, Nelson, M. "Neuroradiographic, endocrinologic and ophthalmic correlates of adverse developmental outcomes in children with optic nerve hypoplasia: a prospective study". Pediatrics. vol. 121. 2008. pp. e653-659.

Ongoing controversies regarding etiology, diagnosis, treatment

Controversy regarding endocrine evaluation for all patients with optic nerve hypoplasia or only those with CNS abnormalities on MRI.

All patients with optic nerve hypoplasia should get a baseline MRI irrespective of laterality.

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