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Optic Nerve Hypoplasia
What is optic nerve hypoplasia?
"Hypoplasia" means smaller than normal. Optic nerve hypoplasia (ONH) refers to small or underdevelopment of the nerve which transmits vision signals from the eye to the brain. This is usually associated with permanent vision loss, which may be mild or severe. ONH may affect either one or both eyes.
How is optic nerve hypoplasia diagnosed?
Although MRI imaging can demonstrate optic nerve hypoplasia, the diagnosis can only be confirmed by direct examination of the eye by an ophthalmologist. Hypoplastic optic nerves usually appear small and pale. Although visual functioning tends to be worse with smaller and/or paler optic discs, it is very difficult to predict visual acuity on this basis alone.
What causes optic nerve hypoplasia?
Although there have been occasional associations of optic nerve hypoplasia with maternal diabetes, maternal alcohol abuse, maternal use of anti-epileptic drugs, and young maternal age (20 years of age or less), most patients have no clearly identifiable cause. There are no known racial or socioeconomic factors in the development of ONH, nor is there a known association with exposure to commonly used pesticides.
Is vision affected with optic nerve hypoplasia?
Vision can range from near-normal levels to severe impairment. Children with ONH may have precisely difficulty locating objects, due to a constricted visual field or impaired depth perception. Some children have light sensitivity.
How does optic nerve hypoplasia present in an infant?
If vision is significantly affected in both eyes, an infant will present with poor vision or shaking of the eyes (nystagmus). If only one optic nerve is small, the eye may cross in or drift out.
Is optic nerve hypoplasia associated with non-visual problems?
Optic nerve hypoplasia can be associated with a variety of brain abnormalities. These most frequently affect structures in the brain midline (septo-optic dysplasia), including the pituitary gland. When the pituitary gland is affected, hormonal deficiencies may result. Brain and hormonal abnormalities are less common in children whose vision loss is mild or unilateral, without nystagmus.
What tests should be done in children with optic nerve hypoplasia?
Associated midline brain anomalies can be identified by either an MRI or CT scan. Hormonal insufficiencies may be detected with specialized blood tests. Evaluation by a specialist in hormonal disorders (pediatric endocrinologist) may be appropriate when hormonal problems are suspected, particularly in children with neonatal low blood sugar, prolonged jaundice, failure to grow normally, or an absence of tissue connecting the brain to the pituitary gland on brain scans.
Does optic nerve hypoplasia get worse over time?
In general, ONH is a stable, nonprogressive condition which does not deteriorate with time. Occasionally, vision may improve over the first few years of life, as the result of brain maturation. In some cases, reduced nystagmus may also occur.
Is there any treatment for optic nerve hypoplasia?
There is no medication or surgery available to treat this condition. However, patching of the better eye may sometimes improve the vision in the more involved eye. Children with significant vision loss in both eyes may benefit from early supportive attention by low vision specialists.
Where can I find more information regarding septo-optic dysplasia?
www.ninds.nih.gov/
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