Optic neuritis

The inflammatory process in the optic nerve - neuritis - can develop both in its fibers and in the membranes. According to the clinical course, two forms of optic neuritis are distinguished - intrabulbar and retrobulbar.

Optic neuritis is an inflammatory, infectious or demyelinating process affecting the optic nerve. It can be classified ophthalmoscopically and etiologically.

Ophthalmoscopic classification

1. Retrobulbar neuritis in which the optic disc appears normal, at least at the onset of the disease. Retrobulbar neuritis in adults is most often associated with multiple sclerosis.
2. Papillitis is a pathological process in which the optic nerve head is affected primarily or secondarily in relation to changes in the retina. It is characterized by hyperemia and edema of the disc of varying degrees, which may be accompanied by parapapillary hemorrhages in the form of "flame tongues". Cells may be visible in the posterior vitreous. Papillitis is the most common type of neuritis in children, but can also occur in adults.
3. Neuroretinitis is papillitis associated with inflammation of the retinal nerve fiber layer. The macular "star" of hard exudate may be absent at first, then develop over days or weeks and become more noticeable after the disc edema resolves. In some cases, there is parapapillary retinal edema and serous macular edema. Neuroretinitis is a rarer type of optic neuritis and is most often associated with viral infections and cat-scratch disease. Other causes include syphilis and Lyme disease. In most cases, it is a self-limited disorder, ending in 6-12 months.

Neuroretinitis is not a manifestation of demyelination.

Etiological classification

1. Demyelinating, the most common etiology.
2. Parainfectious, may be a consequence of a viral infection or vaccination.
3. Infectious, may be rhinogenous or associated with cat scratch disease, syphilis, Lyme disease, cryptococcal meningitis in AIDS, and herpes zoster,
4. Autoimmune, associated with systemic autoimmune diseases.

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Intrabulbar optic neuritis

Intrabulbar neuritis (papillitis) is an inflammation of the intraocular part of the optic nerve, from the level of the retina to the cribriform plate of the sclera. This section is also called the head of the optic nerve. During ophthalmoscopy, this part of the optic nerve is accessible for examination, and the doctor can follow the entire course of the inflammatory process in detail.

Causes of intrabulbar neuritis. The causes of the disease are varied. The causative agents of inflammation can be:

• staphylococci and streptococci,
• pathogens of specific infections - gonorrhea, syphilis, diphtheria, brucellosis, toxoplasmosis, malaria, smallpox, typhus, etc.,
• influenza viruses, parainfluenza, herpes zoster, etc.

The inflammatory process in the optic nerve is always secondary, i.e. it is a complication of a general infection or focal inflammation of any organ, therefore, when optic neuritis occurs, a consultation with a therapist is always necessary. The development of the disease can be caused by:

• inflammatory conditions of the eye (keratitis, iridocyclitis, choroiditis, uveopapillitis - inflammation of the vascular tract and head of the optic nerve);
• orbital diseases (phlegmon, periostitis) and its trauma;
• inflammatory processes in the paranasal sinuses (sinusitis, frontal sinusitis, sinusitis, etc.);
• tonsillitis and pharyngolaryngitis;
• caries;
• inflammatory diseases of the brain and its membranes (encephalitis, meningitis, arachnoiditis);
• general acute and chronic infections.

Of the latter, the most common causes of optic neuritis are acute respiratory viral infection (ARVI), influenza and parainfluenza. The anamnesis of such patients is very typical: 5-6 days after ARVI or influenza, accompanied by an increase in body temperature, cough, runny nose, malaise, a "spot" or "fog" appears before the eye and vision is sharply reduced, i.e., symptoms of optic neuritis occur.

Symptoms of intrabulbar neuritis. The onset of the disease is acute. The infection penetrates through the perivascular spaces and the vitreous body. A distinction is made between total and partial damage to the optic nerve. With total damage, vision decreases to hundredths and even blindness may occur, with partial damage, vision can be high, up to 1.0, but in the field of vision there are central and paracentral scotomas of round, oval and arched shape. New adaptation and color perception are reduced. The indicators of the critical frequency of flickering and lability of the optic nerve are low. The functions of the eye are determined by the degree of involvement of the papillomacular bundle in the inflammatory process.

Ophthalmoscopic picture: all pathological changes are concentrated in the area of the optic nerve disc. The disc is hyperemic, its color may merge with the background of the retina, its tissue is edematous, the edema is exudative. The boundaries of the disc are blurred, but there is no large prominence, as in stagnant discs. The exudate can fill the vascular funnel of the disc and imbibe the posterior layers of the vitreous body. In these cases, the fundus of the eye is not clearly visible. Streaked and striated hemorrhages are noted on or near the disc. Arteries and veins are moderately dilated.

Fluorescein angiography shows hyperfluorescence: in case of total damage to the entire disc, and in case of partial damage to the corresponding zones.

The acute period lasts 3-5 weeks. Then the swelling gradually subsides, the disc borders become clear, and the hemorrhages resolve. The process can end with complete recovery and restoration of visual functions, even if they were initially very low. In severe neuritis, depending on the type of infection and the severity of its course, the nerve fibers die, fragmentarily disintegrate and are replaced by glial tissue, i.e. the process ends with atrophy of the optic nerve. The degree of atrophy varies - from insignificant to complete, which determines the functions of the eye. Thus, the outcome of neuritis is a range from complete recovery to absolute blindness. In case of optic nerve atrophy, a monotonously pale disc with clear borders and narrow filiform vessels is visible on the fundus.

Retrobulbar optic neuritis

Retrobulbar neuritis is an inflammation of the optic nerve in the area from the eyeball to the chiasm.

The causes of retrobulbar neuritis are the same as those of intrabulbar neuritis, to which descending infection is added in diseases of the brain and its membranes. In recent years, one of the most common causes of this form of optic neuritis has become demyelinating diseases of the nervous system and multiple sclerosis. Although the latter does not belong to true inflammatory processes, in all world ophthalmological literature, damage to the organ of vision in this disease is described in the section devoted to retrobulbar neuritis, since clinical manifestations of optic nerve damage in multiple sclerosis are characteristic of retrobulbar neuritis.

Symptoms of retrobulbar neuritis. There are three forms of retrobulbar neuritis - peripheral, axial and transversal.

In the peripheral form, the inflammatory process begins with the optic nerve sheaths and spreads to its tissue along the septa. The inflammatory process is interstitial in nature and is accompanied by the accumulation of exudative effusion in the subdural and subarachnoid space of the optic nerve. The main complaints of patients with peripheral neuritis are pain in the orbital region, which intensifies with eyeball movements (membranous pain). Central vision is not impaired, but uneven concentric narrowing of the peripheral borders by 20-40° is detected in the visual field. Functional tests may be within normal limits.

In the axial form (the most common), the inflammatory process develops predominantly in the axial bundle, accompanied by a sharp decrease in central vision and the appearance of central scotomas in the visual field. Functional tests are significantly reduced.

The transversal form is the most severe: the inflammatory process affects the entire tissue of the optic nerve. Vision decreases to hundredths and even to blindness. Inflammation can begin at the periphery or in the axial bundle, and then spreads along the septa to the rest of the tissue, causing the corresponding picture of inflammation of the optic nerve. Functional tests are extremely low.

In all forms of retrobulbar neuritis, there are no changes in the fundus in the acute period of the disease, only after 3-4 weeks does decolorization of the temporal half or the entire disk appear - descending partial or total atrophy of the optic nerve. The outcome of retrobulbar neuritis, as well as intrabulbar, ranges from complete recovery to absolute blindness of the affected eye.

Treatment of optic neuritis

The main direction of therapy for neuritis (intra- and retrobulbar) should be etiopathogenetic, depending on the identified cause of the disease, but in practice it is not always possible to establish it. First of all, they prescribe:

• antibiotics of the penicillin series and a broad spectrum of action; it is undesirable to use streptomycin and other antibiotics of this group;
• sulfonamide drugs;
• antihistamines;
• local hormonal (para- and retrobulbar) therapy, in severe cases - general;
• complex antiviral therapy for viral etiology of the disease: antiviral drugs (acyclovir, ganciclovir, etc.) and interferonogenesis inducers (poludan, pyrogenal, amixin); the use of corticosteroids is a controversial issue;
• symptomatic therapy: detoxifying agents (glucose, hemodez, rheopolyglucin); drugs that improve oxidation-reduction and metabolic processes; vitamins C and B.

In the later stages, when symptoms of optic nerve atrophy appear, antispasmodics are prescribed that affect the level of microcirculation (trental, sermion, nicergoline, nicotinic acid, xanthinol). It is advisable to conduct magnetic therapy, electrical and laser stimulation.