Optic nerve

Vascular optic disorders

Etiology and pathogenesis of vascular disorders of the optic nerve

Circulatory lesions occur with circulatory disorders in the optic nerve and occupy a significant place in eye pathology. They occur most often in people 50 years of age and older, mainly in those who suffer from systemic vasculopathies (hypertension, atherosclerosis, diabetes mellitus), vasculitis (periarteritis nodosa, giant cell arteritis, Buerger’s disease, radiation vasculitis ), blood diseases, etc. .

Clinic of vascular disorders of the optic nerve

The onset of the disease is mostly acute – from a few minutes to several hours. Against the background of fast-passing fogging, the visual acuity of one eye sharply decreases; the central scotoma and sectoral prolapse (either upper or lower hemianopsia) are determined in the field of view. A complete amaurosis is possible . No pain. Severe edema of the optic disc develops 1-2 days after visual disturbances. After a few days, the edema gradually decreases, the disc turns pale, acquires sharper boundaries, its vessels narrow, i.e. Ophthalmoscopic signs of atrophy begin to appear. After the first days of the disease, vision, with rare exceptions, worsens slightly. If a further decrease in vision is observed, then it occurs stepwise, spasmodically.
The rapid occurrence of changes in the fundus indicate that blood circulation is disturbed in the disk or in a portion of the optic nerve close to it. Therefore, this form of lesion is called anterior ischemic neuropathy . A little later (from several days to several months) in 15-50% of cases the development of the same process in the other eye is possible. Circulatory disorders occur at a considerable distance from the disk; while the rate of onset of symptoms of the disease on the fundus is noticeably lower than that of visual disorders. So, in case of violations in the canalicular part, disc blanching is noted after 8 weeks, in the area of ​​optic intersection – after 5 months, and in case of damage to the optic tract – after about 8 months. In such cases, the diagnosis of posterior ischemic neuropathy is established; while the field of view acts as a determinant of the level of damage. With ischemic neuropathies , complete or partial disturbance of blood circulation with a primary lesion of arterial or venous vessels is possible. 

Treatment of vascular disorders of the optic nerve

Treatment consists in the appointment of vasodilator drugs, heparin, corticosteroids, vitamins, neuroprotective drugs intravenously, intramuscularly, subconjunctival . Recently, the so-called targeted therapy of ischemic injuries of the optic nerve has been developing, which is expressed in the fact that drugs are administered endovascularly directly to the lesion site using special vascular catheters . At the same time, they begin intensive therapy of the underlying disease.
The prognosis is always serious, not only in terms of restoration of vision (minimal improvement on average after six months, and then rarely), but also to save life, because the disease indicates cerebral ischemia, and relapses usually lead to circulatory disorders in larger vessels. 

Retrobulbar neuritis

Etiology and pathogenesis of retrobulbar neuritis

Systemic infections cause the disease (influenza, herpes virus infection, typhus, erysipelas, toxoplasmosis, borelliosis , brucellosis, syphilis, etc.), as well as local inflammatory diseases of the orbit, teeth, hearing organ, sinuses, tonsils, but most often – multiple sclerosis. This pathology can develop with methyl alcohol poisoning due to alcohol, tobacco and other intoxication. Signs of the disease can appear much later, sometimes after many years.
The pathological process is localized in areas of the optic nerve located behind the eye and in the cranial cavity. The course of the disease is acute, less often – chronic. 

Clinic and diagnosis of retrobulbar neuritis

For retrobulbar neuritis, the occurrence of pain behind the eyeball during its movements or with pressure on the eye is characteristic. Pain occurs in more than 90% of cases. This is due to the fact that the inflammatory process captures the tendon ring, equipped with sensitive nerve endings, from which almost all the muscles of the eyeball begin. Visual acuity decreases in many cases to light perception , sometimes to zero, when a direct pupillary reaction to light is disturbed and only friendly is preserved . Central and paracentral scotomas of various sizes appear in the field of vision . In conditions of axial neuritis, the central absolute scotoma is detected in white, red or green. The sizes of the central scotoma are from 2 to 10 ° and more, it can be combined with paracentral deposition; peripheral visual field defects are possible.
In transversal neuritis, cattle fusion and peripheral prolapse are also noted, and its characteristic feature is the absence of ophthalmoscopic changes at the onset of the disease.
Subjective symptoms are ahead of the development of changes in the fundus. The time of onset of signs of pathology in the area of ​​the optic disc depends on the remoteness of the focus of inflammation from the eyeball and can be several days or weeks.
With a sluggish course of the inflammatory process and small objective data, the doctor should be especially careful to avoid the erroneous conclusion about the simulation of the disease, because during this period, due to the absence of changes in the optic nerve head, “the doctor sees nothing and the patient does not see anything.” A thorough study of the visual field and evoked visual potentials, which change in the first place, is necessary. Over time, when the inflammatory process reaches the eyeball, spreading along the nerve fiber, with ophthalmoscopy, hyperemia of the disc, blurring of its borders, changes in the caliber of arterial and venous vessels, and hemorrhages can be detected. The severity of changes in color, borders and caliber of blood vessels is directly proportional to the intensity of the inflammatory process and inversely proportional to the distance to the focus.
In the case of an irregular ophthalmoscopic examination for many weeks and months, the dynamics of changes may go unnoticed, over time, only disc blanching (full or partial) is revealed . If the papillomacular bundle (axial neuritis) is affected, the temporal part of the disc turns pale, since the bundle occupies most of it. With transversal neuritis, when the entire nerve or most of its fibers is affected, after a certain time, a complete blanching of the disk is noted.

Leber Hereditary Optic Nerve Atrophy

The disease was first described by Leber in 1871. It is assumed that atrophy of the optic nerves is a hereditary disease caused by impaired cyanide metabolism. In most cases, the disease is inherited by a recessive type linked to the floor, as men are more likely to get sick than women. But other types of inheritance are possible. Sporadic cases also occur.

Pathological anatomy of optic atrophy

The main morphological changes in this disease are the loss of retinal ganglion cells, demyelination and destruction of the axons that make up the optic nerves. In some cases described in the literature, myelin destruction and degenerative axon changes with the growth of astroglia were found in the brain and spinal cord.

Clinic of atrophy of the optic nerves

The disease develops at a young age, often from 13 to 28 years old, in members of the same family. According to clinical data, the course of the disease resembles bilateral retrobulbar neuritis. Within a few days, against the background of full health, a sharp decrease in vision develops in both eyes, less often vision decreases first in one and then in the other eye. For several weeks, visual acuity continues to decline, and then stops at some level. Complete blindness develops relatively rarely.
At the beginning of the disease, the fundus remains unchanged, sometimes there is only some hyperemia of the nipples of the optic nerves and blurred borders. When examining visual fields, central scotomas are found. In the future, atrophy of the optic nerves develops. In members of the same family, the disease usually proceeds the same way with respect to the time of onset of the first symptoms, the level of vision loss, the nature of the cattle and other symptoms.
Most patients have progressive visual impairment over months and years, but approximately 1/5 of the patients have an improvement in vision in one or both eyes. Several cases of complete restoration of vision are described. In cases of a prolonged course of the disease, symptoms indicative of a more diffuse lesion of the central nervous system may join symptoms of damage to the visual pathway. Cases of progressive dementia, the development of depression , the occurrence of bulbar symptoms, the phenomena of ataxia of the cerebellar and spinal nature, spastic paraplegia are described. In such cases, a differential diagnosis should be made with multiple sclerosis, a tumor of the optic nerves or the chiasmal region.

Treatment of optic atrophy

One of the factors predisposing to the development of the disease is smoking, since tobacco contains cyanide, therefore smoking cessation is one of the important ways to improve the condition of patients.
In addition, it is known that some bacterial infections that cause damage to the urinary tract contribute to an increase in the concentration of cyanides in tissue fluids. Intensive treatment of these diseases reduces or eliminates the phenomena of optic atrophy.

Druze optic disc

Druze optic disc is a relatively rare disease. They are whitish or yellowish roundish different-sized (from a pin head or more), single or in the form of colonies (conglomerates) colloid formations, located mainly along the edge of the disk, as well as in the peripapillary zone. They are determined during ophthalmoscopy in red. Druze, located deep in the disk, as if hidden, which complicates their diagnosis. With fluorescence angiography, disc tissue does not accumulate fluorescein , but drusen under such conditions are more contrasting. Histological examination reveals deposits of calcium salts or colloid degeneration. The number of drusen can increase, with a deep arrangement, they press on the fibers of the optic nerve, causing visual impairment, changes in the field of view. 

Pseudoneuritis of the optic nerve

Pseudoneuritis is observed more often than other abnormalities in the development of the optic nerve, and requires increased attention to itself. The ophthalmoscopic picture resembles this with neuritis and differs only in the absence of dynamics of changes in both the disc and visual functions. Most often, pseudoneuritis is observed in individuals with hyperopia, but can occur with myopia and emmetropia. The cause of pseudoneuritis is the excessive proliferation of neuroglia on the disk. The disk itself is enlarged, hyperemic, grayish in color, with blurry borders, rises above the fundus.
The characteristic symptoms of pseudo – neuritis are the normal ratio of the caliber of arterial and venous vessels, preservation of physiological excavation of the disk. Although the contours are fuzzy, the disc tissue is bright and reflects well. If with repeated ophthalmoscopic examination after 1 -2 months. there is no dynamics of changes, this makes it possible to diagnose pseudo-neuritis . An important additional study in this disease is fluorescence angiography.

Optic atrophy

Etiology of optic atrophy

Atrophic processes in the optic nerve occur as a result of inflammatory or congestive manifestations and are always accompanied by a decrease in visual acuity up to blindness. In addition, atrophy of the optic nerve can be congenital, as well as occur as a result of intoxication (poisoning with quinine, methyl alcohol and other substances, with botulism). Thus, many diseases of the optic nerve culminate in its atrophy, which among the causes of blindness and visual disability in Ukraine takes first place.

Pathogenesis of optic atrophy

The pathogenesis of atrophy is due to etiology. Dystrophy and lysis of optic neurons occur in conditions of the inflammatory process, vascular disorders, intoxication, trauma, stagnation with some differences. Sometimes the etiology of atrophy remains unclear, however, under any circumstances, rupture or destruction of any part of the axon always leads to the death of the neuron.

Clinic of atrophy of the optic nerve

The clinical picture of atrophy is characterized by dilated pupils and an almost complete absence of their reaction to light, as well as tracking and fixation reactions. In bilateral lesions, a “wandering” gaze is noted in patients.
Depending on the causes of atrophy, the ophthalmoscopic picture of the optic disc has some features. Primary (simple) and secondary ( post-inflammatory , post-mortem ) atrophy are distinguished .
Primary atrophy develops as a result of acute chronic intoxication, in conditions of Tabes, vascular sclerosis, impaired integrity of the optic nerve at a considerable distance from the eyeball. In primary atrophy of the border of the disc is sharper than normal, it is pale in whole or in part, the vessels are narrowed. In the case of secondary atrophy, the boundaries of the disc are oiled, it is grayish in color, protrudes somewhat into the vitreous. After a few years, such differences almost disappear. Full and partial atrophy is also distinguished , depending on the course of the disease, stable and dynamic. Complete stable atrophy is not treatable; partial atrophy can be cured, especially if the visual functions are dynamic. Improving working and living conditions helps restore functions.

Treatment of optic atrophy

Treatment of partial atrophy of the optic nerve involves stimulation of the vital activity of preserved nerve fibers. Prescribe tissue therapy, B vitamins, nicotinic acid, glucose, other vasodilating and improving trophic processes drugs, oxygen therapy, ginseng tincture, eleutherococcus extract.
Recently, such treatment methods as acupuncture, the use of a magnetic field, ultrasound, electrical stimulation with the help of special electrodes, which can be brought as close to the nerve as possible, are widely used. Promising in the treatment of partial optic atrophy is the use of the capabilities of endovascular surgery, which is based on the redistribution of blood flowing to the brain, which can significantly improve the provision of blood to the optic nerve during atrophy as a result of ischemia.

Optic disc coloboma

Optic disc coloboma is found, as a rule, together with the coloboma of the choroid or retina itself. A complete coloboma of the disc is extremely rare and has a fairly clear and characteristic ophthalmoscopic picture: at the site of the optic nerve disc, a more or less extensive deepening of an oval blue shape with even pigmented edges is determined; vessels are located in columns in different parts of the disk. Deepening is always 2-3 times larger than the disk itself. Visual acuity decreases depending on the location of the coloboma; blindness may occur if the maculopapillary bundle in the optic nerve is completely damaged . 

Deepening (fossa) of the optic disc

The deepening (fossa) of the optic disc develops less frequently than coloboma. With ophthalmoscopy, a deepening of a round or oval shape is determined, which most often occurs in the temporal part of the optic disc and ranges from 1/8 to 1/3 of its diameter. The functions of the eye in this case are not violated. 

Optic disc pigmentation

Pigmentation of the optic nerve head is characterized by deposition of the pigment of the choroid itself in the form of dots, spots or dashes on the optic disc and, especially, in the region of its vascular funnel, as well as along the vessels on the disc. The eye functions are most often not impaired, therefore, pigmentation of the disc does not require treatment. 

Congenital atrophy of the optic nerves

Congenital atrophy of the optic nerves is detected in newborns relatively rarely. The diagnosis is established on the basis of dilated and almost non-responsive pupils, uncoordinated movements of the eyeballs, nystagmus, lack of fixation of the gaze. The optic nerve disk is white with a grayish tint and clear contours. The vessels of the retina are sharply narrowed. Congenital atrophy of the optic nerves is a consequence of a variety of intrauterine diseases of the central nervous system, including a hereditary one. Not subject to treatment. 

Hypoplasia of the optic nerve

Hypoplasia of the optic nerve is caused by congenital underdevelopment of ganglion cells and is characterized by a decrease in disk size by 2-3 times. With ophthalmoscopy, pallor, tortuosity of the vascular bundle, and deep physiological excavation are determined. Vision with this anomaly is reduced, blindness is possible. The disease most often affects one eye. 

Myelin disk degeneration

Normally, myelination encompasses optic nerve fibers, but sometimes (0.3% of cases) retinal fibers. Radial radiance forms on the optic nerve disk – white shiny spots with a silvery shade (“fox tails”) that fan out into the normally colored part of the fundus without a sharp border go from the disk to the retina. The functions of the eye in this case are not violated, but scotomas corresponding to the location of these spots are formed in the field of view.

local_offerevent_note April 13, 2020

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