Ischemic optic neuropathy is a lesion of the optic nerve caused by a functionally significant circulatory disorder in its intrabulbar or intraorbital region. Ischemic optic neuropathy is characterized by a sudden decrease in visual acuity, narrowing and loss of visual fields, monocular blindness. Diagnosis of ischemic neuropathy requires visometry, ophthalmoscopy, perimetry, electrophysiological studies, Doppler ultrasound of the ocular, carotid and vertebral arteries, fluorescent angiography. If ischemic neuropathy of the optic nerve is detected, decongestant, thrombolytic, antispasmodic therapy, anticoagulants, vitamins, magnetic therapy, electro- and laser stimulation of the optic nerve is prescribed.
Ischemic optic neuropathy usually develops at the age of 40-60 years, mainly in males. This is a serious condition that can cause significant vision loss and even blindness. Ischemic neuropathy of the optic nerve is not an independent disease of the visual organ, but serves as an ocular manifestation of various systemic processes. Therefore, the problems associated with ischemic neuropathy are studied not only by ophthalmology, but also by cardiology, rheumatology, neurology, endocrinology, hematology.
Optic nerve damage can develop in two forms – anterior and posterior ischemic neuropathy. Both forms can occur according to the type of limited (partial) or total (complete) ischemia.
In anterior ischemic optic neuropathy, pathological changes are caused by an acute circulatory disorder in the intrabulbar region. Posterior neuropathy develops less frequently and is associated with ischemic disorders that occur along the optic nerve in the retrobulbar (intraorbital) department.
Anterior ischemic neuropathy is pathogenetically caused by a violation of blood flow in the posterior short ciliary arteries and the resulting ischemia of the retinal, choroidal (prelaminar) and scleral (laminar) layers of the OND. In the mechanism of development of posterior ischemic neuropathy, the leading role belongs to circulatory disorders in the posterior parts of the optic nerve, as well as stenoses of the carotid and vertebral arteries. Local factors of acute circulatory disorders of the optic nerve can be represented by both functional disorders (spasms) of the arteries and their organic changes (sclerotic lesions, thromboembolism).
The etiology of ischemic optic neuropathy is multifactorial; the disease is caused by various systemic lesions and related general hemodynamic disorders, local changes in the vascular bed, microcirculation disorders. Ischemic neuropathy of the optic nerve most often develops against the background of general vascular diseases – atherosclerosis, hypertension, temporal giant cell arteritis (Horton’s disease), nodular periarteritis, obliterating arteritis, diabetes mellitus, cervical spine discopathies with disorders in the vertebrobasilar system, thrombosis of the main vessels. In some cases, ischemic neuropathy of the optic nerve occurs due to acute blood loss during gastrointestinal bleeding, injuries, surgical interventions, anemia, arterial hypotension, blood diseases, after anesthesia or hemodialysis.
With ischemic neuropathy of the optic nerve, one eye is more often affected, but a third of patients may have bilateral disorders. Often, the second eye is involved in the ischemic process after some time (several days or years), usually within the next 2-5 years. Anterior and posterior ischemic optic neuropathy are often combined with each other and with occlusion of the central retinal artery.
Optical ischemic neuropathy, as a rule, develops suddenly: often after sleep, physical effort, a hot bath. At the same time, visual acuity sharply decreases (up to tenths, light perception or blindness with total damage to the optic nerve). A sharp drop in vision occurs in the period from several minutes to hours, so that the patient can clearly indicate the time of deterioration of visual function. Sometimes the development of ischemic neuropathy of the optic nerve is preceded by precursor symptoms in the form of periodic blurred vision, pain behind the eye, severe headache.
With this pathology, peripheral vision is always impaired in one way or another. There may be individual defects (scotomas), prolapses in the lower half of the visual field, prolapses of the temporal and nasal half of the visual field, concentric narrowing of the visual fields.
The period of acute ischemia lasts for 4-5 weeks. Then the edema of the optic nerve gradually subsides, hemorrhages resolve, atrophy of the optic nerve of varying severity occurs. At the same time, visual field defects remain, but can significantly decrease.
To clarify the nature and causes of pathology, patients with ischemic optic neuropathy should be examined by an ophthalmologist, cardiologist, endocrinologist, neurologist, rheumatologist, hematologist.
The complex of ophthalmological examination includes functional tests, examination of eye structures, ultrasound, radiological, electrophysiological studies.
Checking visual acuity reveals its decrease from insignificant values to the level of light perception. When examining the visual fields, defects corresponding to damage to certain areas of the optic nerve are determined.
Ophthalmoscopy reveals pallor, ischemic edema and an increase in the OND, its prominence into the vitreous body. The retina around the disc is edematous, the “figure of a star” is determined in the macula. Veins in the area of compression by edema are narrow, on the periphery, on the contrary, full-blooded and dilated. Sometimes focal hemorrhages and exudation are detected.
Retinal vascular angiography in ischemic optic neuropathy reveals retinal angiosclerosis, age-related fibrosis, uneven caliber of arteries and veins, occlusion of cilioretinal arteries. In posterior ischemic optic neuropathy, ophthalmoscopy in the acute period does not reveal any changes in the OND. With Doppler ultrasound of the ocular, supra-block, carotid, vertebral arteries, changes in blood flow in these vessels are often determined.
Electrophysiological studies (determination of the critical frequency of flickering fusion, electroretinogram, etc.) demonstrate a decrease in the functional thresholds of the optic nerve. When examining the coagulogram, changes in the type of hypercoagulation are detected; when determining cholesterol and lipoproteins, hyperlipoproteinemia is detected. Disease should be distinguished from retrobulbar neuritis, volumetric formations of the orbit and the central nervous system.
Therapy of ischemic neuropathy of the optic nerve should be initiated in the first hours after the development of pathology, since prolonged circulatory disorders cause irreversible death of nerve cells. Emergency care for sharply developed ischemia includes immediate intravenous administration of eufillin solution, taking nitroglycerin under the tongue, inhalation of ammonia vapor. Further treatment is carried out inpatient.
Subsequent treatment is aimed at removing edema and normalizing the trophism of the optic nerve, creating bypass routes of blood supply. It is important to treat the underlying disease (vascular, systemic pathology), normalize the parameters of the coagulation system and lipid metabolism, and correct blood pressure levels.
With ischemic neuropathy of the optic nerve, the administration and administration of diuretics (diacarb, furosemide), vasodilators and nootropic agents (vinpocetine, pentoxifilin, xanthinol nicotinate), thrombolytic drugs and anticoagulants (fenindione, heparin), corticosteroids (dexamethasone), vitamins of groups B, C and E. In the future, magnetic therapy, electrical stimulation, laser stimulation of optic nerve fibers are performed.
Prognosis and prevention
The prognosis of ischemic optic neuropathy is unfavorable: despite treatment, there is often a significant decrease in visual acuity and persistent peripheral vision defects (absolute scotomas) caused by optic nerve atrophy. An increase in visual acuity by 0.1-0.2 can be achieved only in 50% of patients. If both eyes are affected, it is possible to develop low vision or total blindness.
For the prevention, the therapy of general vascular and systemic diseases, the timeliness of seeking medical help is important. Patients who have this disease of one eye need dispensary observation by an ophthalmologist and appropriate preventive therapy.