What happens to the optic nerve
The optic nerve consists of approximately one million retinal nerve cell processes. With prolonged compression, disruption of blood supply, inflammation or toxic effects, some of the fibers die, and connective tissue grows in their place. When examining the fundus, the optic disc becomes pale and the boundaries may change. Atrophy is partial, when the remaining fibers still transmit the image, and complete, when vision is lost. It can be unilateral or bilateral, congenital and acquired.
- Partial atrophy - vision is reduced but preserved
- Complete atrophy - vision is lost
- Primary - the nerve is damaged directly
- Secondary - the outcome of swelling and inflammation of the disc
- Glaucomatous atrophy with characteristic disc excavation
Reasons
In adults, common causes are advanced glaucoma and impaired blood supply to the nerve due to hypertension, atherosclerosis and diabetes. Atrophy can result from optic neuritis, including in multiple sclerosis, compression of the nerve by a tumor or aneurysm, traumatic brain injury, and fractures of the walls of the optic nerve canal. Separately, toxic lesions are distinguished from methyl alcohol poisoning, long-term abuse of alcohol and smoking, as well as side effects of certain drugs. In children, the cause is hereditary diseases and hydrocephalus.
- Glaucoma
- Ischemic optic neuropathy
- Neuritis and multiple sclerosis
- Tumors and aneurysms compressing a nerve
- Head and orbital injuries
- Methanol poisoning, toxic effects of alcohol and tobacco
- Hereditary neuropathies
Symptoms
The main symptom is decreased vision, which cannot be corrected by glasses. It can develop gradually, as in glaucoma, or suddenly, as in a vascular accident. Characteristic loss of areas of the visual field: the central spot, half the field, narrowing along the periphery. The perception of color, especially red, and contrast suffer earlier than others: the world seems faded and dull. Sometimes the patient notices that one eye sees “as if through a film,” and the pupil on it reacts less well to light.
- Persistent decrease in visual acuity
- Loss of areas of the visual field
- Deterioration in color discrimination
- Reducing image contrast
- Poor orientation at dusk
- Weakened pupil reaction to light
Diagnostics
The ophthalmologist checks visual acuity, pupil reaction, examines the fundus with a dilated pupil, and evaluates the color and boundaries of the optic nerve head. Computer perimetry shows which parts of the visual field have fallen out, and optical coherence tomography measures the thickness of the nerve fiber layer and helps monitor the dynamics. Be sure to measure intraocular pressure so as not to miss glaucoma. To find the cause, an MRI of the brain and orbits, blood tests are prescribed, and, if necessary, a consultation with a neurologist and examination for inflammatory and hereditary diseases.
- Visual acuity and pupil reaction
- Fundus examination
- Computer perimetry
- OCT of the nerve fiber layer
- Measuring intraocular pressure
- MRI of the brain and orbits
- Blood tests and consultation with a neurologist
Treatment and rehabilitation
Modern medicine cannot restore dead fibers, so the main task is to eliminate the cause and preserve what remains. For glaucoma, the target intraocular pressure is achieved, for inflammation, anti-inflammatory therapy is carried out, for nerve compression, surgery is discussed, for vascular causes, blood pressure, sugar and cholesterol are controlled. Additionally, drugs that improve nerve nutrition and physical therapy are used, but their effect is limited and they do not replace treatment of the cause. An important part of the help is rehabilitation: magnifying devices, contrast lighting, training in safe movement.
- Reduced intraocular pressure in glaucoma
- Treatment of inflammation and systemic diseases
- Control blood pressure, sugar and cholesterol
- Quitting alcohol and smoking
- Vascular and neuroprotective support as prescribed by a doctor
- Low vision correction products
- Regular observation by an ophthalmologist
