Also known as the second Cranial Nerve or Cranial Nerve II (CN II), the optic nerve is located at the very back of the eye. Our eyes are like windows to the world. The job of the optic nerve is to transmit visual information of the outside world to the brain for processing. This process is carried out by electric impulses.
Like other parts of the body, the optic nerve too can be damaged. This can occur due to eye diseases, trauma, injury, shock, toxins, and even radiation. Diseases of the central nervous system or the brain can also result in optic nerve damage.
What is the Optic Nerve Made of?
Twelve cranial nerves emerge directly from the brain and are composed of a network of neurons. The optic nerve is one of these cranial nerves and is made up of retinal ganglion cells. Each optic nerve contains more than a million nerve fibers.
The nerve fibers in the eye help transmit visual signals from the retina to the brain. Damage to these nerve fibers can cause severe impairment to a person’s vision.
The optic nerve is also a part of the central nervous system of the human body. Visual information such as brightness perception, color perception, visual acuity, and the neurological reflexes, the light reflex and the accommodation reflex, of the eye are transmitted via the Optic Nerve.
What Causes Damage to the Optic Nerve?
Richard, a United States Army veteran, suffers from optic nerve damage. It has permanently impaired both of Richard’s eyes and has left him legally blind. To read more about Richard’s story, click here.
Diseases of the eye, brain and the central nervous system, trauma, injury, shock and overexposure to radiation can damage the optic nerve.
Diseases such as Optic Neuritis, Multiple Sclerosis, Optic Neuropathy, Glaucoma, Leber Hereditary Optic Neuropathy, Anterior Ischemic Optic Neuropathy, Optic Nerve Head Drusen, Optic Nerve Hypoplasia, etc. are known to affect the optic nerve and damage it.
Optic Neuritis is an inflammation or swelling of the optic nerve. The inflammation can occur on its own or is accompanied by a disease such as Multiple Sclerosis, a disease of the brain and the central nervous system. It causes communication problems between the brain and the rest of the body, affecting the nerve fibers while damaging to the optic nerve.
Optic Neuropathy is damage to the optic nerve from any cause, which results in the loss of vision in the affected eye. Loss of color is also a common occurrence in optic neuropathy.
Glaucoma is a set of eye conditions that damage the optic nerve. In glaucoma, the intraocular pressure in the eye builds up gradually and starts affecting the optic nerve. This buildup of pressure slowly damages the optic nerve and may eventually lead to blindness. Click here if you want to learn more about glaucoma. To learn more about the management of glaucoma, click here.
Leber Hereditary Optic Neuropathy LHON is an inherited disease that affects the retinal ganglion cells, the main component of the optic nerve. LHON results in the degeneration of the retinal ganglion cells and may cause temporary or permanent vision loss.
Anterior ischemic optic neuropathy (AION) is a common cause of acute optic neuropathy that causes inflammation of the arteries that supply blood to the optic nerve. This inflammation results in the interruption of blood flow to the optic nerve head or the anterior of the optic nerve. Different diseases or conditions such as Giant Cell Arteritis or temporal arteritis may increase the risk of developing AION.
Non-arteritic AION or NA-AION is also a common type of AION that is caused by either a drop in blood pressure, increased pressure in the eyeball, narrowed arteries, increased blood thickness, and decreased blood flow to the optic nerve. NA-AION can result in the eventual loss of sight if precautionary measures are not taken on time.
Optic Nerve Head Drusen is another condition that causes damage to the optic nerve. Also known as, Optic Disc Drusen, the condition occurs when pockets of mucoproteins and amino sugars calcify in the optic disc.
Another condition that results in optic nerve damage is Optic Nerve Hypoplasia, which occurs due to the underdevelopment of the optic nerve. The optic nerve appears to be abnormally small in this condition due to underdevelopment. Vision loss may occur with optic nerve hypoplasia.
Tumors in the brain, especially those in the pituitary gland of the eye, can also cause damage to the optic nerve. Trauma and injury to the eye or the brain can also affect the optic nerve, resulting in deteriorating vision.
To learn more about diseases and conditions that can cause damage to the optic nerve, click here.
Symptoms of Optic Nerve Damage
Some people will experience pain because of the damage. A person with optic nerve damage will experience mild to severe pain when they move their eyes or while resting.
Vision loss is a common occurrence with optic nerve damage. Since the optic nerve links the brain with the eyes, the visual acuity is affected, resulting in eventual vision loss.
Loss of color vision is another occurrence with optic nerve damage. A person with optic nerve damage will partially suffer from loss of color vision.
Loss of visual perception will also occur if the damage to the optic nerve becomes severe, as the eyes are no longer able to perceive the surroundings.
Other symptoms may include:
Decline in the field of vision
Inflammation in the eye
Temporary or permanent vision loss
Unusual symptoms include numbness or weakness of the limbs, which may be a result of a neurological disorder
Can Optic Nerve Damage be Treated?
Unfortunately, no. Once damaged, the optic nerve cannot be repaired since the damage is irreversible.
The optic nerve is composed of nerve fibers that do not possess the ability to regenerate on their own. The nerve fibers, if damaged, cannot heal on their own. Thus, damage to the optic nerve is permanent while the diseases that cause optic nerve damage are often incurable.
Early detection of optic nerve damage is important, as it can help slow down the effects of the disease or injury, modify the course of the damage and manage some of the symptoms while helping save the vision of a person.
Optic nerve damage may sound terrifying, but by better managing the symptoms of the disease and with regular eye exams, the damage can be controlled. If you found this blog post informative, share it with a friend. If you have any thoughts or concerns you would like to share with us, feel free to contact our experts and they will get in touch with you soon!