What Is Your Optic Nerve?
Open your eyes, and it suddenly becomes clear just how important and spectacular the optic nerve is.
The optic nerve in your eye carries visual information from more than one million ganglion cells found in the retina to your brain. This single optic nerve is responsible for conveying all your sight information, allowing the brain to create what you perceive as vision.
It is an amazing nerve, but it is very delicate. When you have healthy optic nerve function, your vision excels. But if you have any kind of optic nerve damage, such as from glaucoma, inflammation, stroke, tumor, or autoimmune disease, your sight might be in danger.
What Does the Optic Nerve Do?
The primary function of the optic nerve is to take all the sensory information picked up by your eyes and send that information to the brain, where it is translated into sight.
The optic nerve actually begins at the optic disk, a tiny round protuberance that sits at the back of the eye. The optic disk forms axons, which comprise the optic nerve as it travels from the back of the eye to the underside of the front of your brain.
The optic nerve then creates an X-shaped optic chiasm, which allows half of the nerve from each eye to continue on the same side of the brain. The other half crosses over to join the optic fibers from the opposite eye on the other side of the brain. The primary function of the optic nerve is to convey electrical impulses that it receives from 125 million photoreceptor cells, known as rods and cones, to the brain, which then decodes those electrical signals into your vision.
Because it is the superhighway from your eyes to your brain, you can see why optic nerve issues can be so concerning.
Common Optic Nerve Issues
There are many different types of disorders that can affect the optic nerve, and damage to the nerve can affect your vision and may even cause blindness. Common disorders of the optic nerve include the following.
Glaucoma refers to a myriad of conditions that can damage your optic nerve. The main cause of damage is from abnormally high pressure in the eye. When glaucoma damages the optic nerve, visual information from the retina is impeded from reaching the vision centers of your brain. As the optic nerve is damaged over time, blind spots may appear in your peripheral vision and your central vision will eventually be affected as well.
Glaucoma is the leading cause of blindness for those over the age of 60. However, glaucoma is possible in all ages, and oftentimes this disorder has no symptoms or no warning signs.
Vision loss due to glaucoma is permanent, but regular eye exams that include eye pressure measurements can catch the condition before vision loss occurs. The American Academy of Ophthalmology recommends comprehensive eye exams every five to 10 years for those under 40 years old. An eye exam should be scheduled every two to four years for those who are 40 to 54 years old; every one to three years if you’re 55 to 64 years old; and every one to two years if you’re older than 65.
Although many people do not show symptoms, a severe headache, eye pain, and blurred vision could be an indication and you should make an appointment with your eye doctor immediately.
Some studies suggest that regular exercise may also help prevent glaucoma and wearing eye protection can also reduce the risk of eye injuries that can sometimes lead to glaucoma.
If you are diagnosed with glaucoma, your doctor may prescribe glaucoma eye drops, which will need to be used regularly to prevent high eye pressure. Laser treatments or surgery may also be necessary depending on your condition.
Idiopathic Intracranial Hypertension
Idiopathic intracranial hypertension (IIH) occurs when an increase in the fluid around the brain and spinal cord creates too much pressure inside the skull. This increased pressure can cause swelling of the optic nerve and vision loss.
Common symptoms of the disorder include headaches, nausea, vomiting, blurred or double vision, pulsating sounds inside the head, and black outs in vision when standing or changing position.
While uncommon, IIH can affect both men and women and is more common in those who are overweight or on certain high-risk medications such as isotretinoin or tetracyclines.
If your doctor suspects IIH, they will likely order tests such as an eye exam and an MRI. Usually, weight loss can help cure the problem. Medications to relieve pressure and surgery may be needed as well.
Optic neuritis occurs when inflammation damages your optic nerve. Although the cause of optic neuritis is not fully understood, it is believed to result from the immune system mistakenly attacking optic nerve tissue and is most commonly observed in those who have multiple sclerosis. However, it can also result from viral infections, other immune diseases such as lupus, or, although rare, a central nervous system disorder called neuromyelitis optica.
Symptoms of optic neuritis can include eye pain that is worsened by movement, temporary or permanent vision loss in one eye, loss of central or peripheral vision, loss of color vision, or seeing flashing or flickering lights. You should consult your ophthalmologist if you experience any of these indicators of optic nerve inflammation.
Your doctor may examine the optic disk and perform other tests to measure your vision, including peripheral and color vision. You may also undergo an MRI to detect lesions consistent with multiple sclerosis or other conditions that may be affect your vision.
Optic neuritis usually improves on its own, but steroids can help expedite the healing process. If vision loss persists, other treatments such as plasma exchange or IVIG therapy may help some people regain their vision.
Optic Nerve Disorder Treatments
Your eye specialist may recommend a variety of treatments and procedures depending on the specific type of optic nerve disorder, such as:
- Medications to control pressure
- Lifestyle changes like weight loss and avoidance of alcohol
- Low vision aids like glasses and magnifiers
- Specialized eye drops
- Vitamin supplements
- Optic nerve decompression, which removes a part of the canal that the optic nerve runs through
Should vision loss occur regardless of treatment, there are a wide array of optical, electronic, and software tools available to help assist with visual functionality. An ophthalmologist skilled in low-vision problems can help determine the most effective interventions.