Optic Nerve Hypoplasia
What is the optic nerve?
The optic nerve is like a cable that connects the eye to the brain so we can see. The optic nerve starts to form during the early months of pregnancy, before a baby is even born.
Fig. 1: Normal optic nerve.
What is optic nerve hypoplasia?
Optic nerve hypoplasia (ONH) is when the optic nerve doesn't grow fully before a baby is born. This makes the nerve smaller than normal. Small optic nerves can be seen with certain brain growth problems. When this happens, it can be called septo-optic dysplasia or de Morsier syndrome.
Fig. 2: Optic nerve hypoplasia. The nerve in this picture is much smaller than the one shown in figure 1.
HOW DO DOCTORS KNOW IF SOMEONE HAS OPTIC NERVE HYPOPLASIA?
Doctors can tell if someone has ONH by looking at the optic nerve during an eye exam. The optic nerve may look smaller and paler than usual. Sometimes, a yellow circle can be seen around the nerve. Special pictures of the eye, like an OCT scan, can also show signs of a small nerve.
WHAT CAUSES OPTIC NERVE HYPOPLASIA?
Most of the time, we don’t know what causes ONH. It doesn’t seem to be related to race, where a person lives, or whether someone is in contact with bug killing chemicals. Though still rare, ONH can sometimes be seen when a mother uses drugs or alcohol or certain medicines in pregnancy. It may also be seen more when the mother is young or it’s her first pregnancy, but we’re not sure why.
WHAT VISION PROBLEMS ARE THERE IN OPTIC NERVE HYPOPLASIA?
Vision problems from ONH can range from mild blurry vision to complete blindness, and it can affect one or both eyes. People with ONH may have nystagmus (shaking eyes). If only one eye is affected, they might have weak vision or amblyopia. Some may also have eye movement problems or strabismus.
CAN OTHER EYE PROBLEMS LOOK LIKE OPTIC NERVE HYPOPLASIA?
Yes, problems like optic nerve atrophy or Leber congenital amaurosis may look similar to ONH. But with those, the optic nerve is usually a normal size.
IS OPTIC NERVE HYPOPLASIA LINKED TO OTHER HEALTH PROBLEMS?
Yes, some people with ONH can have brain problems. Doctors sometimes use brain scans, like an MRI, to look for brain growth problems (septo-optic dysplasia). People with brain growth problems can also have hormone problems, seizures and other developmental issues. Some people with ONH can have hormone problems even when the MRI is normal.
WHAT TESTS SHOULD BE DONE FOR CHILDREN WITH OPTIC NERVE HYPOPLASIA?
An MRI scan can be very helpful for kids with ONH. It’s also important for children under five to see an endocrinologist (a doctor who treats hormone problems).
DOES OPTIC NERVE HYPOPLASIA GET WORSE OVER TIME?
ONH usually stays the same and doesn’t get worse. Sometimes vision can get a little better, and nystagmus (eye shaking) may get better as well.
IS THERE ANY TREATMENT FOR OPTIC NERVE HYPOPLASIA?
There is no medicine or surgery to fix ONH. But doctors can help with other eye problems that can come with ONH. It is important to get regular eye check-ups to treat other eye problems and get the best possible vision. Kids with really blurry vision in both eyes do better when they have help from low vision specialists at a young age.
MORE INFORMATION ABOUT OPTIC NERVE HYPOPLASIA CAN BE FOUND AT:
EyeWiki
National Institute of Neurological Disorders and Stroke
National Organization for Rare Disorders
Updated 10/2024
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