Optic nerve and retina
The optic nerve is formed from the neurons of the retinal cells in the area of the optic nerve head. Further from the cavity of the orbit, passing behind the eye (retrobulbar), the optic nerve passes into the cavity of the skull (middle cranial fossa) and forms the intersection of the optic nerve at the level of the sella turcica. After the intersection of the optic nerves at the level of the Turkish saddle, bundles of nerve fibers form the optic tract. Ophthalmoscopic examination of the patient's eye allows identifying changes in the fundus associated with various forms of optic nerve pathology.
The internal carotid artery supplies blood to the optic nerve and retina through the optic artery. In approximately 25% of cases of clinically manifested occlusion (blockage of the lumen) of the internal carotid artery, transient blindness in one eye occurs episodically. In the future, there is a high probability of permanent blindness. Describing such an episode, the patient can inform the doctor about the feeling of a shadow descending and disappearing or crossing the field of view, or about the loss of peripheral parts of the visual field. There may also be complaints of blurred vision, blurred vision in the affected eye, or the absence of the upper or lower half of the visual field. Most often, these symptoms persist for only a few minutes. Less often, simultaneously with a stroke, occlusion (blockage of the lumen) of the ophthalmic artery of the central retinal artery is noted.
Types of diseases of the optic nerve and retina
Diseases of the optic nerve and retina have several factors of origin and differ in the place of localization and the type of pathological process:
- optic disc edema
- optic neuritis
- retrobulbar optic neuritis
- optic nerve neuropathy
- optic disc atrophy
- macular changes
- retinal vascular changes
Based on these above factors, a further plan of neurological examination and treatment of a patient with diseases of the optic nerve and retina is being built.
edema of the optic disc
Optic disc edema is non-inflammatory edema caused by an increase in intracranial pressure. At the same time, hyperemia, edema of the optic nerve head, its prominence into the vitreous body, and blurred boundaries are observed. Retinal veins are dilated, twisted. At the height of stagnation of the optic nerve head, multiple hemorrhages in the retina are noted.
A characteristic feature of edema of the optic nerve head is the long-term preservation of visual acuity, however, as the edema progresses, it undergoes atrophy (atrophy after stagnation), which is accompanied by a decrease in visual acuity and the development of blindness.
Stagnant changes in the fundus are observed in all diseases accompanied by an increase in intracranial pressure (tumors, hydrocephalus, meningitis, encephalitis). Cases of edema of the optic nerve head, in which there are also signs of damage to the optic nerve or tract by a pathological process, are called complicated edema of the optic nerve head.
Optic neuritis is an inflammatory process in the optic nerve throughout its entire length, including the optic nerve head. In the fundus of the optic nerve, hyperemia of the optic nerve head, washout (blurring) of its borders, dilation of arteries and veins, hemorrhages, and foci of necrosis on the surface of the nipple and in the surrounding retina are noted. Characterized by an early impairment of visual functions simultaneously with the development of ophthalmoscopic changes.
Optic neuritis occurs in patients with acute inflammatory diseases of the nervous system (meningitis, encephalitis, encephalomyelitis, neurosyphilis).
Retrobulbar optic neuritis
Retrobulbar optic neuritis is an inflammation of the optic nerve that does not extend to the optic head. At the same time, changes in the fundus in patients are uncharacteristic, there are only mild hyperemia and blurring of the boundaries of the optic nerve head.
Retrobulbar optic neuritis is often unilateral. Clinically significant neurological signs of retrobulbar optic neuritis are:
- vision loss
- field disturbances
Retrobulbar optic neuritis occurs in patients with multiple sclerosis, opticomyelitis, Leber's familial atrophy of the optic nerves, optic-chiasmal arachnoiditis.
The phenomena of retrobulbar neuritis are possible in other acute and chronic inflammatory diseases of the brain (encephalitis, meningitis, neurosyphilis).
Optic nerve neuropathy
Optic nerve neuropathy is a disease that is a consequence of disorders in the vessels of the optic nerve and is observed in cerebral hypertension, spasm, and embolism of the nerve vessels, etc. Clinically, optic nerve neuropathy can manifest itself in patients with neurological deficits in the form of loss of visual fields, color flashes (photopsy).
Optic disc atrophy
Atrophy of the optic nerves is a disease that, during ophthalmoscopy, reveals blanching of the optic nerve head, vasoconstriction with preservation (with primary atrophy), or blurring of the boundaries (with secondary atrophy) of the optic nerve head. Secondary optic disc atrophy develops after all processes accompanied by optic neuritis or stagnant disc. Primary (simple) optic disc atrophy develops in patients with syphilitic damage to the nervous system, compression of the nerve by a tumor, scar, neuroma, gumma, etc.
The combination of optic nerve atrophy in one eye with the development of a stagnant disc in the other (Foerster-Kennedy syndrome) is observed with a tumor, gum, or tuberculoma of the basal surface of the frontal lobe of the brain. Atrophy of the optic nerve occurs on the side of the tumor.
Macular changes occur in the childhood form of the Tay-Sachs familial amaurotic idiocy when there is a grayish opacity in the area of the macula with a dark red color in its central part. In the juvenile form of this disease, patients have pigmentary degeneration of the retina in the central regions.
Retinal vascular changes
Retinal vascular changes are the occurrence of an impaired course and caliber of the retinal vessels. retinal vascular changes are observed most often in hypertension, cerebral vascular sclerosis. In hypertension, several stages of vascular changes in the fundus are distinguished: at the stage of initial changes, vasoconstriction, corkscrew tortuosity of venules in the paramacular region (Gvist's symptom), and arterial spasms are noted.
At the stage of organic changes in the fundus, vascular sclerosis (retinal angiosclerosis), narrowing of the caliber with compaction of their walls (the phenomenon of copper wire), and the phenomenon of arterio-venous intersection are revealed. Later, in severe forms of hypertensive encephalopathy, retinopathy of the retina is observed, in which the edema of the optic disc, degenerative changes, and hemorrhages in the retina, as well as neuropathy of the optic nerve head, join the above phenomena.
Treatment of diseases of the optic nerve
Neurological treatment for diseases of the optic nerve and retina is selected by the doctor individually in each case. It can include both a complex of conservative procedures and surgical treatment:
- neurolysis of the nerve trunk (in the case of a scar on the nerve, compression of the nerve by a tumor (meningioma), etc.)
- stimulation of the optic nerve and oculomotor muscles
- vitamins of group "B", "C" and "E"
- antiviral drugs
- homeopathic remedies, etc.
The duration of neurological treatment and its frequency in diseases of the optic nerves and retina are dictated in the future by the functional state of the optic nerve itself, the retina, and the restored lost light sensitivity.