An inflammation caused in the optic nerve, generally reported with a partial or in rare cases a complete vision loss is known as optic neuropathy. This condition is also otherwise termed as ‘Optic Neuritis’ or ‘Demyelinating Optic Neuritis’. The optic nerve is the combination of nerve cells that usually help in transmitting the input from the eye to the brain, whereby the process of vision takes place.
Hence, any loss or damage caused to some of the fibers of this nerve is said to lead to optic neuropathy. However, this condition is almost treatable and it is said to resolve on its own or with the help of treatment with corticosteroids for speedy recovery.
What Is Optic Neuropathy?
The optic nerve plays a significant role in maintaining our visual ability. This nerve is associated with a bundle of nerve cells, which originate from the retina and transport the messages to the visual cortex in the brain in order to be processed as visual images.
There is also a sheath called myelin surrounding the optic nerve, which usually acts as a protective shield and greatly aids in speedy transmission of the electrical impulses to the brain, thus providing clear vision.
Hence, any damage or inflammation occurred to the optic nerve cells or the myelin sheath leads to the condition known as optic neuropathy. This condition is generally associated with a sudden loss of vision, diminished color vision or pain in the eye.
Types Of Optic Neuropathy
Optical neuropathy can be of the following types.
Compressive Optic Neuropathy
This condition is said to arise when the optic nerve is compressed due to the lesions caused within the orbit or the optical canal due to infections, inflammation or tumors.Patients suffering from this kind of optic neuropathy, usually experience a disc swelling associated with a bulging out of the eye and more or less a normal vision with mild color deficits.
Traumatic Optic Neuropathy
This kind of optic neuropathy results from a trauma caused due to a direct or an indirect injury nearer to the eye. Injuries caused directly to the head such as bullets and forceps cause a direct damage to the optical nerve.
On the other hand, injuries such as blunt trauma occurred to the forehead due to accidents, falls, loss of consciousness accompanied with serious brain injuries can also cause indirect injuries to the optical nerve.
Infiltrative Optic Neuropathy
Sometimes, certain conditions like inflammation, tumors or infections may cause infiltration into the optic nerve. Conditions such as sarcoidosis, bacteria, viruses and fungi are considered to mainly cause such infiltration thereby leading to optical neuropathy.
Nutritional Optic Neuropathy
Nutritional deficiencies such as malnutrition and undernourishment usually deplete the body out of the essential vitamins and nutrients vital for a good health. Such conditions may instigate a nutritional optic neuropathy in some patients.Apart from these, this condition is also triggered in well nourished patients due to a pernicious anemia or a deficiency of vitamin B12.
Mitochondrial Optic Neuropathy
As mitochondria is vital for supplying the energy needed for maintaining the life cycle of the retinal ganglion cells, any derangements in its transportation is said to cause mitochondrial optic neuropathy.
Toxic Optic Neuropathy
In some cases, intoxications caused by methanol and ethylene glycol can be the reason to cause toxic optic neuropathy. Drugs like ethambutol and amiodarone which are used to treat medical conditions also at times trigger this condition.
Hence, if any symptoms of optic neuropathy are found in those undergoing medication of these drugs, should immediately contact the doctor for an optical evaluation because discontinuance of these drugs can improve and bring back their vision.
In addition to these, tobacco exposure can also cause a slow and progressive optic neuropathy in people, and the chances are more for those suffering from malnutrition along with the habit of tobacco intake.
Hereditary Optic Neuropathy
Sometimes, people may also experience a permanent and progressive optic neuropathy due to heredity.
Though in most of the cases of optic neuropathy there is no apparent cause, however, it is said to generally cause due to nerve diseases, infections and inflammatory immune responses. Actually, the most attributable cause for optic neuropathy is considered to be Multiple Sclerosis and it can be the first symptom of this nerve disease.Apart from multiple sclerosis, optic neuropathy can also result due to neuromyelitis optica, lymes disease, mumps, measles, sinusitis, sarcoidosis, tuberculosis, nutritional deficiencies, intoxication and inheritance.
Optic neuropathy generally affects people within the age of 18 to 45, and it is said to affect women twice more than men. Those who have been diagnosed with multiple sclerosis are more likely to develop this condition and moreover certain genetic mutations are also responsible to increase this risk factor. Optic neuropathy is usually found common among the whites or those living at high latitudes.
Signs And Symptoms
The usual symptoms reported with the onset of optic neuropathy are
1. A sudden mild to severe decline of vision loss, which may gradually progress within a couple of days and get worse with heat or exercise.
2. Pain in and around the eye, usually experienced during the eye movement.
3. Distorted color vision, especially the red color seeming to be washed out or faded.
4. Blurriness or the appearance of flashing lights in the eye.
Hence, those who find worsening of their vision for more than two weeks and eventually feel that there is no improvement even after eight weeks should immediately report to a doctor.
In most cases of optic neuropathy, there is no treatment involved and the condition is left to resolve on its own. However, if it is felt that medication is necessary, then this condition is treated with a combination of intravenous steroid injections and administration of oral steroids.The intravenous injections are generally prescribed for a couple of days, where these injections are directly injected into the veins and the oral steroid such as prednisone is prescribed for about two weeks.
Though administration of steroids helps in reducing the optic nerve inflammation, they could lead to some of the possible side effects such as mild mood changes, stomach upset, insomnia and weight gain. In few cases, when optic neuropathy results due to the onset of multiple sclerosis, resolving the latter may automatically resolve the former issue.The better part of optic neuropathy is that about 90 to 95% of people suffering from this condition regain their vision normally within a period of six to twelve months. Though the vision regained may not be as exactly as it was before, they may still be able to recover to the maximum.
The chances of recurrent attacks of optic neuropathy are more with the patients suffering from multiple sclerosis and nueromyelitis optica, and it is comparatively less in others who do not suffer from any of these conditions.