Diseases of the optic nerve
The most common cause of damage to the optic nerve is an accident or violent impact (traffic accidents or similar) in which the optic nerve is squeezed or pulled, for example when entering the skull. Bleeding into the orbit of the eye (e.g. after blows to the eye with a fist) can also cause the nerve fibers to be squeezed due to an increase in pressure. Bacterial or viral infections of the orbit (orbital aphlegmons) of various origins can also lead to damage of the optic nerve.
In the context of multiple sclerosis, in the course of which different structures of the central nervous system can be affected, damage to the optic nerve with visual field failures is not uncommon. In the course of glaucoma, an increase in pressure in the eye occurs through which the fine vessels that supply the retina and the optic nerve are squeezed. The undersupply leads to irreversible damage to the affected cells after a few hours, with permanent visual field loss.
Various brain tumors can cause reversible and irreversible damage by pressure on the optic nerve. Tumors of the pituitary gland (pituitary gland) are most likely to do so because of their close relationship to the optic nerve and cause the characteristic picture of “blinkered vision” (bitemporal hemianopsia), since the fibers running in the intersection of the visual pathways are particularly affected. The optic nerve can be affected by various diseases.
For example, inflammation of the optic nerve can be caused by an infection. In about 30% of cases, however, inflammation of the optic nerve is also a symptom of multiple sclerosis. An optic nerve congestion or a congestion papilla is a swelling of the part of the optic nerve that leads directly to the eye.
A so-called optic nerve infarction describes the closure of the artery that supplies the optic nerve head. If the optic nerve is injured, the field of vision may be impaired or even blindness may result, depending on the extent of the injury. Optic nerve atrophy describes a loss of nerve cell strands, which is usually irreversible and can also lead to complete blindness.
Furthermore, tumor diseases can also play a role. These can either come from outside and compress the optic nerve or originate at the optic nerve itself. An injury to the optic nerve is usually rather rare, since the optic nerve is located behind the eye and is therefore not as susceptible to injury as other parts of the eye.The injury occurs more often in the context of contusions (for example in the context of a swelling eyeball) or for example also in the context of a craniocerebral trauma.
Occasionally, burns also occur, for example as a result of prolonged direct exposure to the sun. This can be intensified by binoculars or similar. Depending on the location of the injury, it can have various consequences.
If, for example, the papilla, i.e. the orifice of the optic nerve in the eye, is damaged, this can sometimes lead to complete blindness. If, on the other hand, only parts of the nerve fibers are damaged, vision may be reduced or impaired as a result. Inflammations of the optic nerve are divided into two basic types according to their location.
If the inflammation occurs at the point of entry (papilla) of the optic nerve into the eyeball, it is called papillitis. If it is located outside the eyeball (bulbus), it is called retrobulbar inflammation or retrobulbar neuritis. The causes of both types of inflammation can be varied.
Often, an allergic reaction or disturbed function of the body’s defense cells is present. However, inflammatory processes from adjacent structures, such as the paranasal sinuses or the base of the skull, can also affect the optic nerve. Other causes can be infectious diseases such as viral infections or borreliosis as well as harmful substances such as methanol, lead or quinine (in drugs or as a bittering agent in food).
In rare cases, retrobulbar inflammation can be an early symptom of multiple sclerosis. The inflammation usually manifests itself in a very strong and sudden reduction of visual acuity and a dull pain behind the eye, which is intensified by pressure on the eyeball. However, no irritation of the eye can be detected from the outside.
In order to detect papillitis, the doctor will perform an ophthalmoscopy of the back of the eye, examining the papilla for signs of inflammation or bleeding. In the case of retrobulbar inflammation, a special EEG is usually performed to check the electrical conduction within the nerve and thus its function – this is known professionally as visually evoked potentials (VEPs). The therapy of the optic nerve inflammation is carried out by means of cortisone, which is administered directly into the blood stream over several days.
The success of the therapy depends on the underlying disease. Complete healing can be achieved, but in most cases damage to the nerve cells remains and thus a permanent reduction in visual acuity. Unfortunately, optic nerve atrophy is usually a non-reversible loss of nerve cells of the optic nerve.
This can be caused by a variety of factors. Examples are toxic damage, such as alcohol or medication, reduced arterial blood flow due to arterial occlusion, an inflammatory change due to, for example, a syphilis infection, or the hereditary disease of liver optic atrophy. Optic nerve atrophy can lead to deterioration of vision, color perception disorders and even blindness.
Since the damage is irreperable, the therapy consists only of preventing the progression of the atrophy and treating the underlying disease if it is present. Various types of tumors can develop on the optic nerve. The distinction is based on the type of tissue from which the respective tumor cells are derived.
In neurinomas, these are the mantle cells of the nerve, the so-called Schwann cells. This type of tumor is benign, but can become a problem if it exerts pressure on the nerve through its space-consuming growth and damages it. Neurofibromas also develop from the nerve sheaths.
However, these are usually a concomitant symptom of the hereditary disease neurofibromatosis type 1, which is accompanied by other symptoms and organ involvement. They are primarily harmless, but carry a certain risk of degeneration. Since the optic nerve, as a bulge of the brain, is also surrounded by the meninges, tumors, so-called meningiomas, can also originate from these.
These grow very slowly and usually occur in middle age. Furthermore, gliomas can develop from the supporting tissue of the nerves. These also show a rather slow growth, but are mostly found in children.
The therapy for all tumor types depends mainly on the localization and whether they cause complaints or restrictions. In most cases, they are surgically removed if they are easily accessible. If this is not possible, radiotherapy and chemotherapy can be used.
Swelling of the optic nerve can have various causes. If the optic nerve itself is swollen, this is usually a sign of inflammation.The inflammation of the optic nerve and the associated swelling can be caused by infections such as syphilis, sarcoidosis or a fungal infection. It can also be caused by systemic multiple sclerosis.
Furthermore, tumorous swelling of the optic nerve may also occur. Depending on the localization and extent of the swelling, the symptoms are very varied and range from slight visual impairment to disturbances in color perception and complete blindness when the optic nerve is severely compressed by the swelling. In glaucoma, also known as glaucoma, increased internal pressure in the eye leads to long-term damage to the papilla, the orifice of the optic nerve in the eye.
The causes of the increase in intraocular pressure are not always clear. Risk factors can include diabetes mellitus, inflammation or certain drugs. The main symptom of glaucoma is a reduction in vision, since the direct compression of the papilla leads to a lack of transmission of visual perceptions to the brain. Often glaucoma is also associated with pain and redness of the eye and should be treated by a doctor as soon as possible.
