Cerebral edema of the optic nerve
The optic nerve begins with a disc formed by sensitive retina fibers. Fibers receive information about light and color. Then on optic nerve information enters the subcortical structures andfurther into the cortex of the occipital lobe. In them, visual signals are recognized, coded and transmitted to other centers of the brain for final processing and conscious perception. The optic nerve is divided into four sections: intraocular, intraorbital, intracanal and intracranial. The intraocular region is represented by a disc of the optic nerve, whose diameter is approximately 1 mm. In a healthy person, the disc has a pale pink color. The length of the orbital part is about 3 cm. Further along the bony canal, the nerve enters the brain, where the next section begins, which extends to the intersection of the optic nerves. The distance from the optic disc to the chiasma is 3.5-5.5 cm.
Symptoms of optic nerve diseases
- Decreased visual acuity. Blindness.
- Decreased perception of light intensity.
- Changes in the fields of vision.
Causes of optic nerve diseases
Causes of optic nerve diseases can be very different.
Edema of the optic disc
Edema of the optic disc (edema) withoutsigns of inflammation can be one- or two-sided. Sometimes the patient gets dark in the eyes. If you quickly eliminate the cause that caused swelling, then the ailments soon disappear. Otherwise, the atrophy of the optic nerve. the nervous tissue dies and the patient is blinded. Bilateral edema of the optic discs is observed in tumors or abscesses of the brain. increased intracranial pressure, congenital deformities of cranial bones. Sometimes edema of optical discs occurs with anemia. leukemia and pulmonary emphysema. Unilateral edema occurs most often after trauma or surgery. There are also congenital defects of the optic nerve, for example, pseudoedema. Sometimes druses are visible on the optic nerve disk, bleeding from the retina appears.
These include papillitis and retrobulbar neuritis. A person has a significant visual impairment, a change in the visual fields. For retrobulbar neuritis, a headache worse with eye movement is characteristic. Other symptoms of inflammation: violation of color vision, flickering before the eyes, doubling and trembling in the eyes. When papillitis there are significant changes in the optic disc. With retrobulbar neuritis, changes occur only after 3 weeks. Inflammation of the optic nerve can develop with infectious diseases,metabolic disorders, diseases of the nervous system, blood, kidneys, increased blood pressure, inflammation of the fundus and internal structures of the eye. Most often, the ailments are associated with the defeat of the nerve itself, for example, with ischemia, gliomas, infringement of the optic nerve, as well as with demyelinating diseases.
Atherosclerosis and other diseases of blood vessels, blood circulation is disrupted, which leads to damage to the optic nerves.
The affected nerve can not perform its functions. Possible atrophy of both the entire optic nerve and its individual fibers. Partial atrophy can be suspected with a sharp decrease in visual acuity and changes in the visual fields. At full atrophy of the optic nerve the patient loses sight. Atrophy of the optic nerve can also be caused by trauma to the skull, glaucoma, retinal diseases, blood vessels and large blood loss. Atrophy of the optic nerve can also be observed in certain hereditary diseases.
Tumors of the optic nerve are rare. More often there are gliomas. Gliomas can cause visual impairment. Usually the tumor is removed by the operative method.
The defeat of the optic nerve can occur whenstrong poisoning, for example, methanol. Methanol is very easy to mix with ethyl alcohol. The defeat of the optic nerve is possible with the use of certain drugs, for example, quinine.
More articles on this topic: