Definition
The inflammation of the optic nerve is called neuritis nervi optici. The optic nerve is the second cranial nerve, i.e. it is part of the central nervous system, the brain. It begins at the retina of the eye and transmits the information received by the eye to the brain.
For this reason, the disease often occurs with other symptoms that affect the brain. Inflammation of the optic nerve occurs most frequently in people between the ages of 18 and 45 and affects women more often than men. The causes of the disease can be very different and either one or both eyes are affected.
Many underlying conditions can lead to inflammation of the optic nerve. The most common cause (about 20-30% of cases) is the autoimmune disease Multiple Sclerosis (MS). In this disease, the body produces antibodies against the sheath structures of the nerves (myelin sheaths), causing them to become inflamed and reduce the conductivity of the nerves.
Gradually, more and more nerves perish. In a typical course of the disease, the myelin sheaths of the optic nerves are affected first. Here the inflammation of the optic nerve occurs bilaterally.
Systemic lupus erythematosus (SLE), another autoimmune disease, can also be the cause of optic nerve inflammation. This is a systemic disease, meaning that the whole body is affected. The formation of antibodies causes tissue damage, which initially manifests itself as skin rashes.
In addition, many organs such as the lungs, heart and kidneys can be damaged. The central nervous system is also often affected. In principle, diseases that specifically affect the central nervous system can also lead to inflammation of the optic nerve, as this is part of it.
These include, for example, meningitis or brain abscesses, i.e. inflammation of the brain. Infectious diseases caused by bacteria can also affect the optic nerve in the course of time. Lyme disease, which is transmitted by ticks, has a strong effect on the central nervous system in its chronic course, e.g. in the form of inflammation of the optic nerves.
But also malaria, typhoid fever, diphtheria or syphilis can lead to this. Viral infections can lead to inflammation of the optic nerves more frequently in children than in adults. This is triggered by measles, mumps, rubella, chickenpox, whooping cough or by the Ebstein-Barr virus, which causes the whistling glandular fever.
An inflammation of the paranasal sinuses can also be passed on to the bones and from there to the optic nerve, where it can lead to an inflammation. In addition, poisoning through excessive consumption of alcohol or quinine can also lead to inflammation of the optic nerve. Quinine is used as a remedy for malaria and is also found in some medications for flu-like infections.
Hereditary diseases can also lead to inflammation of the optic nerve, but are comparatively rare. First, inflammation of the optic nerve leads to a loss of visual acuity (visual acuity). With slow progression, this is usually not immediately noticed by the patient.
However, in most cases, central visual field deficits, the so-called central scotoma, occur suddenly, i.e. within a few hours (sometimes even days). This means that visual perception can no longer take place in the middle of the visual field, i.e. in the area that can be seen with one eye. The affected person then sees a black dot in the middle of his or her image of the environment.
Depending on whether one or both eyes are affected, this is noticeable on one or both sides. In extreme cases, this loss of visual field can become worse and worse until it leads to complete blindness. However, this is extremely rare and the visual impairment usually regresses over time.
However, pain often occurs when pressure is applied to the affected eye and when the patient moves the eye when turning his gaze. These are often perceived as headaches in the area of the eye socket and are present continuously, but become worse when pressure is applied. Sometimes the pupillary reflex is also impaired during the course of the disease, i.e. the narrowing of the pupil when the light comes in and the dilation in darkness no longer function properly.
Red-green perception can also be disturbed. As a rule, the symptoms improve after about 2 to 4 weeks. However, it is possible that a slight contrast disturbance in vision remains.
If the disease returns again and again, this is called a chronic course.This can lead to the loss of vision becoming progressively worse and the optic nerve becoming increasingly irritated by the inflammation and then atrophied. In this case, vision cannot be completely restored. In case of existing visual field loss or headaches in the area of the eye socket, an ophthalmologist should be consulted.
The ophthalmologist examines the back of the eye (ophthalmoscopy) by shining a certain lamp into it and reflecting it. Here he can see the exit of the optic nerve from the eye (blind spot). This examination is often inconspicuous despite the presence of an inflammation of the optic nerve, since only the exit point and not the entire nerve can be detected.
Only in rare cases, when the inflammation affects just this starting point of the nerve, can the ophthalmologist see a swelling, the so-called papilledema. This swelling can also be a sign of increased intracranial pressure, which is why the cause of this finding must be clarified further. One speaks either of an intrabulbar inflammation, i.e. an inflammation in the eyeball, or, in contrast to this, of a retrobulbar inflammation in case of damage behind the eyeball.
The ophthalmologist also checks visual acuity by reading out numbers from a distance with one eye at a time. The field of vision is also determined in order to detect possible failures. This procedure is called visual field perimetry and is based on the fact that the patient should be able to see with one light point each that approaches him from the side.
The pupillary reflex is also tested by the ophthalmologist shining a small lamp into each eye and observing the reactions of the pupils. Normally, when shining into one eye, the pupils of both eyes should contract (consual pupil reaction). However, if the optic nerve of one eye is inflamed, this will cause both pupils not to contract sufficiently.
The Swinging Flashlight Test offers a more detailed examination. If the ophthalmologist detects abnormal findings, these should be clarified further. Magnetic resonance imaging (MRI) of the brain with a contrast medium can be helpful here, as it can reveal the areas that may have defects in their envelope structures.
These areas are called demyelination foci and can indicate multiple sclerosis. In addition, the nerve conduction velocity can be measured by a neurologist. If this is reduced, this is an indication of an inflammation of the optic nerve.
It is very important in the diagnosis to check for neurological diseases such as multiple sclerosis. In addition, attention should be paid to whether fever or a skin rash is added to the visual complaints, as this indicates an infection. A blood test may also be necessary to detect any changes in the blood count or to determine whether bacteria are present in the blood.