What Is an Optic Nerve Pit?

An optic nerve pit is a backward protrusion of tissue seen on the optic nerve. It is hard to notice; in fact, most people are not aware that they have one until an eye doctor observes the pit during an exam.

Optic nerve pits are not that common. One early report found that they occur in about 1 in 11,000 patients. They are congenital, meaning that people are born with them. Most people have it in just one eye, but 15% will have an optic nerve pit in both eyes. Males and females are equally affected by optic nerve pits.

This article will explain more about what an optic nerve pit is, its symptoms, how it's diagnosed, and available treatments.

Structure and Causes

Your optic nerve, also called cranial nerve 2, or CN 2, connects the retina, located in the back of the eye, to the brain. It is responsible for transmitting visual information (what you see) from the retina to the brain. The optic nerve is made up of more than 1 million nerve fibers.

An optic nerve pit, also called an optic disc pit or sometimes an optic hole, is considered a pocket or defect located within the optic nerve.

An optic nerve pit may occur due to incomplete formation of the eye in an embryo (the early stage of human development, when organs are formed). Researchers debate the exact cause of an optic nerve pit.

Optic Nerve Pit Symptoms

Many adults with an optic nerve pit will have no symptoms from it, and symptoms also are rare in children. If vision changes do occur, they are more likely to happen in a person's 20s or 30s. Vision changes result in about 50% of people with an optic nerve pit.

Vision changes are caused by fluid that pools under the macula. The macula is the central part of the retina. The accumulation of fluid under the macula without a break in the retina is called a serous retinal detachment. A serous retinal detachment can cause:

• Blurred vision
• A blind spot in your field of vision
• Seeing objects as smaller than they are
• Seeing straight lines as curved

Retinal detachments are considered a medical emergency. Vision problems that involve the macula and are associated with an optic nerve pit are often called maculopathies.

Diagnosing an Optic Nerve Pit

An optic nerve pit is not something you can detect just by looking at your eye.

Many people with an optic nerve pit will not notice any change to their vision. The most common way it is found is during a routine eye exam. During these exams, the eye doctor may notice an optic nerve pit while examining the optic nerve and retina.

An eye doctor can observe an optic nerve pit with direct or indirect ophthalmoscopy. This involves the use of a handheld or head-worn device to help the doctor see the back of the eye.

The eye doctor also can obtain a closer look via a slit lamp biomicroscopy binocular exam. A slit lamp is a special microscope with a bright light attached to it. This tool lets the professional examining your eye closely look at the structures at the front and inside of your eyes.

The eye doctor may also perform a visual field test, which measures your entire field of vision. This will help them see if there are any visual field defects due to the optic nerve pit.

Treatment

A person with an optic nerve pit does not need treatment if they do not have any vision symptoms caused by it. The eye doctor may just recommend monitoring and returning for regular eye exams.

If the macula has fluid buildup associated with a serous retinal detachment, then the eye will require treatment. These treatments may include:

• Surgery: There are a few types of surgery that eye doctors can perform for an optic nerve pit. The most common one is called a pars plana vitrectomy. Sometimes surgery alone is needed, and other times it is used in combination with other therapies. This type of surgery has shown visual improvement in more than 50% of people with an optic nerve pit. It also is frequently successful in reattaching the retina if a full retinal break has occurred.
• Injecting gas tamponade: This involves the use of gas injected in the eye during retinal surgery to help fix a retinal detachment. This procedure usually removes 50% to 75% of the fluid. However, there is a frequent need to reinject gas due to the fluid returning.
• Inner retinal fenestration: This approach forms a passage for the fluid under the macula to drain and travel to the vitreous. The vitreous is a gel-like fluid in the eye. This approach helps to resolve fluid accumulation and to improve vision.
• Laser photocoagulation: This treatment uses a special laser to prevent fluid from entering the macula. However, this therapy has had less success than other treatments used for optic nerve pits.

Results from the treatment of an optic nerve pit can vary. If maculopathy develops, then about 80% of patients may have a visual acuity that can dip to 20/200 or worse (normal vision is 20/20). However, surgery has about an 87% success rate.

In some people, vision does not return to normal despite treatment.

Summary

An optic nerve pit is a congenital defect near the optic nerve that occurs in about 1 in 11,000 people. It more commonly affects one eye vs. both eyes. Most people do not know that they have it until an eye doctor observes the pit during an exam.

An optic nerve pit often does not need treatment, nor does it cause visual effects. When it does cause vision changes due to maculopathy, treatment options include a variety of surgeries. Surgery can help improve vision, although some people may not return to normal vision even after treatment.

A Word From Verywell

If an eye doctor tells you that you have an optic nerve pit, follow any instructions on how often you should return for an eye exam. Those exams give your doctor a chance to monitor the optic nerve pit and increase the chance for good vision. Talk to your doctor about your long-term risk for maculopathy. Let your healthcare team know if you have any changes to your vision.