Optic Nerve Function
Optic Nerve Function.
The eye is one of the most complex and important sensory organs in the human body. It provides the ability to see in both bright and dim light, focusing on objects both near and far. Its three types of cone cells are able to distinguish millions of distinct colors and produce the high quality images that the body relies on for many daily activities.
The optic nerve carries visual information from your eye to your brain. Optic neuritis (ON) is when your optic nerve becomes inflamed. ON can flare up suddenly from an infection or nerve disease. The inflammation usually causes temporary vision loss that typically happens in only one eye.
How many nerve are in the eyes
According to science, each human optic nerve contains between 770,000 and 1.7 million nerve fibers, which are axons of the retinal ganglion cells of one retina. In the fovea, which has high acuity, these ganglion cells connect to as few as 5 photoreceptor cells; in other areas of retina, they connect to many thousand photoreceptors.
The cornea is a transparent dome-shaped tissue that forms the front part of your eye. … The cornea does not contain any blood vessels, but instead contains many nerve endings that make it extremely sensitive. That is why a scratch or a loose eyelash is so painful.
What Causes Optic Neuritis?
Optic neuritis usually occurs in adults younger than 45 and affects more women than men. The condition is common in people who have multiple sclerosis (MS), which occurs when the body’s own immune system attacks and destroys protective nerve coverings.[ Important Info On Age Related To Macular Degeneration Wet ]
1. Infections such as toxoplasmosis
2. Ocular herpes
3. Other viral infections
5. Neurological disorders
6. Leber hereditary optic neuropathy, an inherited form of vision loss that affects mostly males in their 20s or 30s
6. Nutritional deficiency
7. Toxins, including alcohol and tobacco
During an eye exam, your eye doctor will look for signs of optic neuritis by conducting tests to evaluate whether you have reduced vision. When optic neuritis is present, the pupil always appears abnormal (afferent pupillary defect). This means the pupil actually dilates instead of constricting in the presence of bright light. Depending on the severity of optic neuritis, the optic nerve may appear normal or swollen.
If your optometrist or ophthalmologist suspects you have optic neuritis, a visual field test usually will be performed to determine if you have peripheral vision loss.You also might be referred to a specialty clinic to undergo an MRI of the brain to detect possible underlying causes of optic nerve inflammation.
Some symptoms of optic nerve damage?
These types of symptoms may precede vision loss due to optic neuritis. Optic neuropathy more generally describes optic nerve abnormalities or damage. Also, Optic neuritis usually affects one eye. As stated by Mayor Clinic symptoms might include:
Most people who develop optic neuritis have eye pain that’s worsened by eye movement. Sometimes the pain feels like a dull ache behind the eye.
2. Vision loss in one eye
Most people have at least some temporary reduction in vision, but the extent of loss varies. Noticeable vision loss usually develops over hours or days and improves over several weeks to months. Vision loss is permanent in some cases.
3. Visual field loss
Side vision loss can occur in any pattern.
4. Loss of color vision
Optic neuritis often affects color perception. You might notice that colors appear less vivid than normal.
5. Flashing lights
Some people with optic neuritis report seeing flashing or flickering lights with eye movements.
What happens if there is damage to the optic nerve?
The optic nerve is a bundle of more than 1 million nerve fibers that carry visual messages. You have one connecting the back of each eye (your retina) to your brain. Damage to an optic nerve can cause vision loss. The type of vision loss and how severe it is depends on where the damage occurs. It may affect one or both eyes..
There are many different types of optic nerve disorders, including:
1. Glaucoma. Glaucoma usually happens when the fluid pressure inside the eyes slowly rises and damages the optic nerve.
2. Optic neuritis is an inflammation of the optic nerve. Causes include infections and immune-related illnesses such as multiple sclerosis. Sometimes the cause is unknown.
3. Optic nerve atrophy is damage to the optic nerve. Causes include poor blood flow to the eye, disease, trauma, or exposure to toxic substances.
4. Optic nerve head drusen are pockets of protein and calcium salts that build up in the optic nerve over time
Risk factors for developing optic neuritis include:
1. Age. Optic neuritis most often affects adults ages 20 to 40.
2. Sex. Women are much more likely to develop optic neuritis than men are.
3. Race. In the United States, optic neuritis occurs more frequently in whites than it does in blacks.
4. Genetic mutations. Certain genetic mutations might increase your risk of developing optic neuritis or multiple sclerosis.
When to see a doctor
Eye conditions can be serious and medical attention should be given to any case relating to eye. Some can lead to permanent vision loss, and some are associated with other serious medical problems. Contact your doctor if:
1. You develop new symptoms, such as eye pain or a change in your vision.
2. Your symptoms worsen or don’t improve with treatment.
3. You have unusual symptoms, including numbness or weakness in one or more limbs, which can indicate a neurological disorder.
Nerve in the Eye Regeneration Strategies
Researchers have made great progress in understanding the process of optic nerve degeneration and regeneration in glaucoma. Molecular factors have been identified for nerve fiber growth in the central nervous system. Though there are different medical strategies, Researchers hope to prevent expression of molecules that suppress axon growth using molecular biology techniques. For example, antibodies may be introduced to block the inhibition and allow nerve fibers to re-grow. Other strategies are in development as well:
1. Nerve grafts have been tried. However, when optic nerves are damaged, they respond by forming scar tissue; nerve fibers have not successfully regenerated across the scarred areas.
2. Nanotechnology has been used to create a protein nanofiber structure through which axons can regenerate.
3. Cellular implants are engineered cells that can give physical support to neuronal fibers and provide regeneration-promoting chemicals to aid in axonal growth.
4. Genetic manipulations might help to stimulate optic nerve regeneration, but there is much research yet to be done in this area.