Retrobulbar neuritis is an inflammatory lesion of the area of the optic nerve located between the orbit and the optic junction. It is accompanied by a decrease in visual acuity, the appearance of prolapses, limitations of visual fields, pain when moving the eyeball. Diagnosis includes a comprehensive neurological and ophthalmological examination. Treatment is carried out with antibacterial / antiviral pharmaceuticals, glucocorticosteroids, antihistamines, diuretics, neuroprotective agents, if necessary, detoxification, physiotherapy is carried out.
Retrobulbar neuritis rarely has a primary truly inflammatory character, usually it is a secondary pathology associated with various brain lesions (primarily with multiple sclerosis). In this regard, the disease is the subject of study of neurology. Neuritis of the optic nerve in the intraocular area is called intrabulbar and is considered in the framework of ophthalmology. In both variants, diagnostics and therapeutic measures require the joint participation of neurologists and oculists. Retrobulbar neuritis occurs at different ages, mainly in 20-40 years. Statistics show that the incidence among women is 2 times higher than among males.
Causes of retrobulbar neuritis
The etiology of the disease is diverse. Retrobulbar neuritis of a truly inflammatory genesis occurs in infectious, chronic inflammatory processes in the body against the background of immunodeficiency conditions. These factors are:
- Chronic viral infections. The leading role belongs to cytomegalovirus, the causative agent of infectious mononucleosis, herpes infection. Persistent viruses in the body cause a perversion of immune reactivity. As a result of the production of antibodies to their own nerve tissues, autoimmune inflammation of the extra-ocular part of the optic nerve occurs.
- Chronic infectious foci. More often, the source of infection is located near foci (sinusitis, otitis, chronic tonsillitis), less often — more distant (pyelonephritis, cystitis). Hematogenic introduction of infectious agents into the optic nerve tissue leads to the development of inflammation.
- Inflammatory processes of the orbit: uveitis, iridocyclitis, chorioretinitis. Hematogenic, perineural spread of the process causes damage to the retrobulbar portion of the optic nerve. Total optical neuritis is more often observed.
Secondary retrobulbar neuritis develops due to damage to cerebral tissues. The main causal pathology is the following diseases:
- Multiple sclerosis. The process of demyelination of nerve fibers extends to the optic nerves, accompanied by an inflammatory reaction. Retrobulbar neuritis is the first symptom in 65-80% of cases of multiple sclerosis.
- Brain tumors. Volumetric formations of the optic intersection (chiasmal gliomas), neoplasms of a different localization, squeezing the chiasmal area, disrupt blood supply, metabolism of optic nerve tissues. The result is the development of symptoms of neuritis.
- Neuroinfections (neuroSPID, neurosyphilis, tuberculous meningitis, Lyme disease) can occur with damage to the retrobulbar part of the optic nerve. Inflammatory changes are caused by direct infection with infectious agents.
In some cases, retrobulbar neuritis occurs due to toxic damage to the optic nerve. Exogenous intoxication is caused by exposure to pesticides, methyl alcohol, iodine preparations, and some medications. Endogenous toxicoses develop against the background of dysmetabolic diseases, kidney failure, pregnancy.
The optic nerve consists of a million fibers originating in the retina and ending in the subcortical visual ganglia. Various etiofactors lead to ischemia, demyelination, inflammatory changes in the visual fibers in the area from the orbit to the chiasm (visual intersection). These processes cause a violation of the function of transmitting information from the image-perceiving retinal receptors, which is clinically manifested by a deterioration in visual acuity, a disorder of color perception, loss in optical fields. Further progression of the process is accompanied by irreversible damage to an increasing number of optical fibers, filling the formed destruction sites with connective tissue growths. Such atrophic changes lead to irreversible vision loss.
The clinical picture varies significantly with lesions of the central (axial) and peripheral parts of the nerve trunk. Depending on the localization of the pathological process , retrobulbar neuritis is classified into three main forms:
- Axial. It is characterized by a predominant lesion of the axial beam. It is manifested by a sharp drop in central vision, the appearance of central cattle. The axial form is most common.
- Peripheral. Inflammation is localized in the peripheral fibers, accompanied by the formation of a subcellular exudate, provoking pain syndrome. Central vision is preserved, typically narrowing of the visual fields.
- Transversal. The inflammatory process that has begun in the peripheral or axial part extends to the entire diameter of the nerve trunk. Visual function is impaired up to amaurosis (complete blindness).
The following classification is based on the variability of the course of the disease, according to which two variants are distinguished:
- Acute. Sudden rapidly progressive loss of vision. The acute variant of the course is characteristic of primary neuritis. It occurs mainly at a young age.
- Chronic. Symptoms increase gradually against the background of cerebral lesion. In the future, there are periods of remission and exacerbation. The transition of the acute variant to the chronic one is possible.
Symptoms of retrobulbar neuritis
The leading manifestations of the disease are variable visual disorders, which are of a one- or two-sided nature. In 60% of cases, there is a significant deterioration in visual acuity. In the acute form, vision decreases in the period from several hours to two days, in the chronic form, the process takes 1-2 weeks. Patients describe visual dysfunction as “a veil before the eyes”, “blurring of the image”. Some patients complain of “flashes of light” suddenly appearing in their eyes. The gradual onset of the disease proceeds with deterioration of visual adaptation at dusk (hemeralopia).
Changes in visual fields are characterized by the appearance of dark spots (cattle) in front of the eyes, narrowing of the visible area. They can be combined with a drop in visual acuity. In most cases, retrobulbar neuritis occurs with a violation of color perception (dyschromatopsia). Due to a marked decrease in visual function, dyschromatopsia is not felt by patients, it is diagnosed only during an ophthalmological examination.
According to various data, 53-88% of patients complain of pain behind the eyeball, which increases with eye movement, especially when looking up. The severity of the pain syndrome varies from moderate discomfort to intense pain, possibly the addition of cephalgia. Pain syndrome is most typical for the peripheral form. Secondary retrobulbar neuritis is combined with signs of brain damage, in the case of multiple sclerosis, it may remain the only clinical manifestation for a long time.
In the absence of timely therapy, limited possibility of relief of causal cerebral pathology, retrobulbar neuritis acquires a chronic course. There is a mass death of nerve fibers, their replacement by connective tissue that is unable to conduct nerve impulses. Descending atrophy of the optic nerve develops, leading to a persistent decrease in vision, disabling the patient. Total atrophy of the optic nerve leads to complete amaurosis.
The diagnostic task is to establish the diagnosis of “retrobulbar neuritis” with the determination of its etiology, with the mandatory exception of multiple sclerosis. The diagnostic algorithm includes a thorough collection of anamnesis (initial symptoms, the rate of their progression, previous illnesses), a complete ophthalmological and neurological examination.
- Visometry. It reveals a decrease in visual acuity to 0.2-0.1 diopters, sometimes to light perception. The resulting violations are not corrected by lenses.
- Definition of color perception. The decrease in brightness, saturation of color perception leads to errors of the patient when viewing color tables. In the absence of changes in the visual disc (OND) on the fundus, color perception disorder is an important indicator
- Perimetry. Central, paracentral, and peripheral scotomas are found in the fields of vision. The bitemporal narrowing of the visual fields indicates the transition of the process to chiasm.
- Ophthalmoscopy. It determines puffiness, hyperemia of OND, petechial hemorrhages, with the development of atrophy — disc paleness. In 65% of cases, acute retrobulbar neuritis in multiple sclerosis is not accompanied by changes in the fundus.
- Assessment of neurological status. The neurologist’s study of the motor, sensory, reflex, cognitive, and mental spheres makes it possible to identify/exclude cerebral and focal neurological symptoms indicating the presence of cerebral pathology.
- Visual VP. The progression of the process is characterized by an increasing increase in latency time (by 31-35% of the norm), a decrease in the amplitude of evoked visual potentials on the lesion side.
- MRI of the brain. Allows you to visualize the primary pathology of the brain (inflammatory foci, tumor, demyelination zones) or make sure it is absent.
- Ultrasound of the optic nerve. It is used relatively recently, it is an auxiliary diagnostic method. Ultrasound measurement of the diameter of the nerve trunk section located at a distance of 3 mm beyond the orbit reveals its increase by 30-60%.
- Examination of cerebrospinal fluid. It is necessary if neuroinfection is suspected. Along with the study of the chemical, cellular composition of the cerebrospinal fluid, PCR studies, ELISA, aimed at determining the pathogen, are carried out.
It is necessary to differentiate retrobulbar neuritis from ischemic optic neuropathy, intrabulbar lesion, opticomyelitis. Ischemic neuropathy develops against the background of vascular disorders in atherosclerosis, hypertension, diabetes. Differential diagnosis may require retinal angiography, ultrasound of the ocular arteries. Intrabulbar neuritis is characterized by changes in OND from the first days of the disease. Opticomyelitis occurs with symptoms of spinal lesion — myelitis.
Treatment of retrobulbar neuritis
Therapy is based on the etiopathogenetic principle, corresponds to the etiology of the lesion. Retrobulbar neuritis of secondary genesis requires the elimination of the root cause: tumor removal, immunocorrective treatment of multiple sclerosis, neuroinfection therapy. The main components of complex therapy are:
- Etiotropic treatment. In case of bacterial infection, broad—spectrum antibiotics are used, in case of viral infection – antiviral drugs, interferon inducers.
- Anti-inflammatory therapy. It is carried out by retrobulbar administration of glucocorticosteroid drugs. In severe cases, systemic corticosteroid therapy is indicated.
- Decongestant therapy. It is aimed at reducing the swelling of the affected nerve trunk. Diuretics (acetazolamide, furosemide), antihistamines (chloropyramine, desloratadine) are prescribed.
- Neuroprotective treatment. In order to maintain and restore nerve function as soon as possible, B vitamins, nicotinamide, vitamin C, microcirculation-improving agents (pentoxifylline) are used.
- Detoxification. It is indicated for toxic damage, neuroinfection, severe inflammatory processes. It is carried out by intravenous drip administration of dextran, salt solutions.
- Physical therapy. In the absence of contraindications, magnetotherapy and laser therapy are used. At the first signs of atrophy, electrical stimulation is advisable.
Prognosis and prevention
The primary acute variant of the disease has a predominantly favorable course with almost complete restoration of visual function. Chronic forms are characterized by a persistent recurrent course, accompanied by a drop in vision. The progression of the underlying pathology leads to persistent disabling disorders. On average, the number of optic nerve atrophy is 22-25%. Prevention is aimed at increasing the body’s resistance to infectious agents, timely elimination of inflammatory foci (sinusitis, otitis, cystitis), adequate treatment of diseases of the eyeball.