Optic Nerve Hypoplasia
Underdeveloped Optic Nerve
Optic nerve hypoplasia (ONH) is a congenital condition where the optic nerve is underdeveloped. Since the optic nerves function to carry the visual signal to the brain, their underdevelopment can cause vision impairment.
What causes ONH?
In most cases, the cause of ONH is never found. However, sometimes the underdeveloped optic nerve can be associated with maternal factors during pregnancy such as young maternal age; diabetes; use of alcohol, drug or some epilepsy drugs. ONH can be associated with other mid-line brain developmental disorders, such as a rare congenital condition known as septo-optic dysplasia (SOD) or de Morsier syndrome. For these reasons, further tests may be needed including brain MRI and an evaluation of the pituitary function by a pediatric endocrinologist.
How is ONH diagnosed?
ONH is diagnosed by dilating the eye and examining the appearance of the optic nerve. Children may be referred to the pediatric ophthalmologist because of poor vision or another abnormal finding. The diagnosis of ONH may be confirmed with an MRI scan.
How does ONH affect vision?
The optic nerve appearance does not predict the severity of vision loss. Vision can range from nearly-normal all the way to completely blind in the affected eye. The vision loss is typically stable and sometimes may even improve some with age. Nystagmus (eye shaking) is common in optic nerve hypoplasia, especially if it affects both eyes, and may also limit vision. Strabismus (eye misalignment) is even more common.
Is there treatment for ONH?
Currently, there is no known effective treatment for ONH. Another cause is contributing to ONH, such as amblyopia, part-time patching of the better eye may provide some improvement. Wearing protective safety glasses full time is vital to protect the better eye. A low vision evaluation can be beneficial for patients with poor vision in both eyes. Stem cell treatments for ONH, many of which are done in some foreign countries, have not been proven effective and come with significant cost and safety concerns.