Optic atrophy (optical neuropathy) is a partial or complete destruction of nerve fibers that transmit visual stimuli from the retina to the brain. Atrophy of the optic nerve leads to a decrease or complete loss of vision, narrowing of the visual fields, impaired color vision, paleness of OND. The diagnosis is made when identifying characteristic signs of the disease using ophthalmoscopy, perimetry, color testing, visual acuity determination, craniography, CT and MRI of the brain, B-scanning ultrasound of the eye, retinal vascular angiography, etc. In case, treatment is aimed at eliminating the pathology that caused this complication.
H47.2 Optic atrophy
Various diseases in ophthalmology occur in 1-1.5% of cases; from 19 to 26% of them lead to complete atrophy of the optic nerve and incurable blindness. Pathomorphological changes are characterized by destruction of axons of retinal ganglion cells with their glial-connective tissue transformation, obliteration of the capillary network of the optic nerve and its thinning. Atrophy of the optic nerve can be a consequence of a large number of diseases occurring with inflammation, compression, swelling, damage to nerve fibers or damage to the vessels of the eye.
Causes of optic atrophy
Factors leading can be eye diseases, CNS lesions, mechanical damage, intoxication, general, infectious, autoimmune diseases, etc.
The causes of damage and subsequent atrophy of the optic nerve are often various ophthalmopathology: glaucoma, retinal pigmented dystrophy, occlusion of the central retinal artery, myopia, uveitis, retinitis, optic neuritis, etc. The risk of damage to the optic nerve may be associated with tumors and diseases of the orbit: meningioma and glioma of the optic nerve, neurinoma, neurofibroma, primary cancer of the orbit, osteosarcoma, local orbital vasculitis, sarcoidosis, etc.
Among the diseases of the central nervous system, the leading role is played by tumors of the pituitary gland and posterior cranial fossa, compression of the area of the intersection of the optic nerves (chiasm), purulent-inflammatory diseases (brain abscess, encephalitis, meningitis), multiple sclerosis, traumatic brain injuries and damage to the facial skeleton, accompanied by injury to the optic nerve.
Often, this disease is preceded by the course of hypertension, atherosclerosis, starvation, vitamin deficiency, intoxication (poisoning with alcohol surrogates, nicotine, chlorophos, medicinal substances), large simultaneous blood loss (more often with uterine and gastrointestinal bleeding), diabetes mellitus, anemia. Degenerative processes in the optic nerve can develop with antiphospholipid syndrome, systemic lupus erythematosus, Wegener’s granulomatosis, Behcet’s disease, Horton’s disease.
In some cases, disease develops as a complication of severe bacterial (syphilis, tuberculosis), viral (measles, measles rubella, ARVI, herpes zoster) or parasitic (toxoplasmosis, toxocarosis) infections.
Congenital atrophy of the optic nerve occurs in acrocephaly (tower-shaped skull), micro- and macrocephaly, craniofacial dysostosis (Cruson’s disease), hereditary syndromes. In 20% of cases, the etiology of optic atrophy remains unclear.
Disease can be hereditary and non-hereditary (acquired). Hereditary forms include autosomal-dominant, autosomal recessive and mitochondrial. The autosomal dominant form can have a severe and mild course, sometimes combined with congenital deafness. Autosomal recessive form occurs in patients with Vera, Wolfram, Burnevilly, Jensen, Rosenberg-Chattorian, Kenny-Coffey syndromes. The mitochondrial form is observed with mutation of mitochondrial DNA and accompanies Leber’s disease.
Acquired optic atrophy, depending on etiological factors, can be primary, secondary and glaucomatous in nature. The mechanism of development of primary atrophy is associated with compression of peripheral neurons of the visual pathway; the OND is not changed, its boundaries remain clear. In the pathogenesis of secondary atrophy, OND edema occurs due to a pathological process in the retina or the optic nerve itself. The replacement of nerve fibers by neuroglia is more pronounced; OND increases in diameter and loses clarity of boundaries. The development of glaucomatous atrophy of the optic nerve is caused by the collapse of the lattice plate of the sclera against the background of increased intraocular pressure.
According to the degree of discoloration of the optic nerve disc, initial, partial (incomplete) and complete atrophy are distinguished. The initial degree of atrophy is characterized by a slight paling of the OND while maintaining the normal color of the optic nerve. With partial atrophy, disc paling is noted in one of the segments. Complete atrophy is manifested by uniform paling and thinning of the entire optic nerve disc, narrowing of the fundus vessels.
According to localization, ascending (with damage to retinal cells) and descending (with damage to optic nerve fibers) atrophy are distinguished; according to localization, unilateral and bilateral; according to the degree of progression, stationary and progressive (determined during dynamic observation by an ophthalmologist).
Symptoms of optic atrophy
The main sign of optic atrophy is a decrease in visual acuity that cannot be corrected with glasses and lenses. With progressive atrophy, a decrease in visual function develops within a few days to several months and can end in complete blindness. In the case of incomplete atrophy of the optic nerve, pathological changes reach a certain point and do not develop further, and therefore vision is partially lost.
With atrophy of the optic nerve, visual function disorders can manifest themselves as a concentric narrowing of the visual fields (disappearance of lateral vision), the development of “tunnel” vision, color vision disorder (mainly green-red, less often blue–yellow part of the spectrum), the appearance of dark spots (cattle) in areas of the visual field. It is typical to detect an afferent pupillary defect on the side of the lesion – a decrease in the pupil’s response to light while maintaining a friendly pupillary reaction. Such changes can be noted both in one and in both eyes.
Objective signs of optic atrophy are revealed during ophthalmological examination.
When examining patients with optic atrophy, it is necessary to find out the presence of concomitant diseases, the fact of taking medications and contact with chemicals, the presence of bad habits, as well as complaints indicating possible intracranial lesions.
During a physical examination, an ophthalmologist determines the absence or presence of exophthalmos, examines the mobility of the eyeballs, checks the reaction of the pupils to light, the corneal reflex. It is mandatory to check visual acuity, perimetry, color perception research.
Basic information about the presence and degree of optic atrophy is obtained by ophthalmoscopy. Depending on the causes and form of optical neuropathy, the ophthalmoscopic picture will differ, but there are typical characteristics found in various types of optic atrophy. These include: paleness of OND of varying degrees and prevalence, changes in its contours and color (from grayish to waxy), excavation of the disc surface, a decrease in the number of small vessels on the disc (Kestenbaum’s symptom), narrowing of the caliber of retinal arteries, changes in veins, etc. The OND condition is clarified using tomography (optical coherent, laser scanning).
Electrophysiological examination reveals a decrease in lability and an increase in the threshold sensitivity of the optic nerve. With the glaucomatous form of optic atrophy, an increase in intraocular pressure is determined using tonometry. The pathology of the orbit is detected by means of a survey radiography of the orbit. Examination of retinal vessels is carried out using fluorescent angiography. The study of blood flow in the orbital and supra-block arteries, the intracranial section of the internal carotid artery is performed using ultrasound Dopplerography.
If necessary, an ophthalmological examination is supplemented by a neurological status study, including consultation with a neurologist, X-ray of the skull and Turkish saddle, CT or MRI of the brain. If a patient has a volumetric brain formation or intracranial hypertension, a consultation with a neurosurgeon is necessary. In the case of pathogenetic connection of optic atrophy with systemic vasculitis, a rheumatologist’s consultation is indicated. The presence of orbital tumors dictates the need for an ophthalmologist to examine the patient. Therapeutic tactics for occlusive lesions of the arteries (orbital, internal carotid) is determined by an ophthalmologist or vascular surgeon.
In case of optic atrophy caused by infectious pathology, laboratory tests are informative: ELISA and PCR-diagnostics, with atrophy of hereditary genesis – genodiagnostics.
Differential diagnosis of optic atrophy should be performed with peripheral cataract and amblyopia.
Treatment of optic atrophy
Since atrophy of the optic nerve in most cases is not an independent disease, but is a consequence of other pathological processes, its treatment should begin with the elimination of the cause. Patients with intracranial tumors, intracranial hypertension, cerebral vascular aneurysm, etc. a neurosurgical operation is indicated.
Nonspecific conservative treatment of optic atrophy is aimed at preserving visual function as much as possible. In order to reduce inflammatory infiltration and edema of the optic nerve, para-, retrobulbar injections of dexamethasone, intravenous infusions of glucose and calcium chloride, intramuscular administration of diuretics (furosemide) are carried out.
To improve blood circulation and trophism of the optic nerve, injections of pentoxifylline, xanthinol nicotinate, atropine (parabulbar and retrobulbar); intravenous administration of nicotinic acid, euphyllin; vitamin therapy (B2, B6, B12), injections of aloe extract or vitreous; administration of cinnarizine, piracetam, riboxin, ATP, etc. are indicated. In order to maintain a low level of intraocular pressure, pilocarpine instillations are carried out, diuretics are prescribed.
In the absence of contraindications for optic atrophy, acupuncture, physiotherapy (electrophoresis, ultrasound, laser or electrical stimulation of the optic nerve, magnetotherapy, endonasal electrophoresis, etc.) is prescribed. With a decrease in visual acuity below 0.01, any treatment is not effective.
Prognosis and prevention
If the atrophy of the optic nerve was diagnosed and treated at an early stage, it is possible to preserve and even slightly increase vision, but complete restoration of visual function does not occur. With progressive atrophy of the optic nerve and no treatment, complete blindness can develop.
To prevent atrophy of the optic nerve, timely treatment of ocular, neurological, rheumatological, endocrine, infectious diseases is necessary; prevention of intoxication, timely blood transfusion with profuse bleeding. At the first signs of visual impairment, an optometrist’s consultation is necessary.