Amaurosis fugax is a one–sided, sudden short-term vision loss that develops due to trauma or progressive ischemia. Visual dysfunction is characterized by the appearance of a “dark curtain” in front of the eyes against the background of complete well-being or aura in the form of photopsias. There is a pain syndrome. The mobility of the eyeballs is limited. To make a diagnosis, visometry, ophthalmoscopy, biomicroscopy, ultrasound of the eye are used. Hormonal preparations, nicotinic acid, antispasmodics, plasma substitutes, xanthines, membrane stabilizing agents are used in the treatment of amaurosis fugax.
G45.3 Amaurosis fugax
Amaurosis fugax (transient macular blindness) is a rare pathology, which in most cases is a complication after diagnostic or therapeutic manipulations in otolaryngological practice. Transient vision loss is often temporary, but cases have been described when it precedes amaurosis. There are no statistical data on the prevalence of the disease. The disease can develop at any age. Men and women suffer equally often. Amaurosis fugax is ubiquitous, but irreversible course is more often observed in residents of countries with a low level of socio-economic development.
The cause of the disease is usually improper anesthesia or surgical intervention. Less common is sudden loss of vision, which occurs without visible prerequisites. In this case, we are talking about an idiopathic form of the disease. The main causes of secondary amaurosis fugax:
- Regional anesthesia. Clinical manifestations of pathology occur after anesthesia during rhinological operations. Most often, such complications are observed with submucosal resection of the nasal septum.
- Interventions on the upper jaw. Eye damage during surgical manipulations on the upper jaw body is possible with damage to the trigeminal nerve or the subglacial canal. The probability of the spread of the pathological process into the orbital cavity increases with destructive processes in the bone tissue.
- Rehabilitation of the paranasal sinuses. Puncture and washing of the wedge–shaped sinus is one of the causes of temporary bilateral vision loss. The development of blindness may also be associated with the penetration of a puncture needle into the nerve fibers during puncture of the maxillary sinus.
- Rhinological diseases. Violation of the technique of lower conchotomy with hypertrophy of the nasal conchae leads to persistent unilateral amaurosis. The reflex mechanism of blindness, which is a consequence of incorrectly prescribed pharmacotherapy, is more favorable in prognostic terms.
- Temporal arteritis. With this pathology, large and medium-sized vessels are affected, including the ocular arteries. The long course of the disease leads to a violation of the trophic optic nerve, which is the basis of amaurosis fugax.
- Embolism of the central retinal artery. Embolism causes the lumen of the vessel to overlap. Pathology is characterized by a rapidly progressive violation of blood flow in the arteries of the retina, manifested by complete blindness.
The development of amaurosis fugax after anesthesia during operations on the nasal cavity is due to the anatomical proximity of the orbit and nose. The eye socket, the external nose and the nasal structures are characterized by a common blood supply and innervation. Scientists believe that the onset of symptoms is associated with vascular spasm under the influence of high concentrations of adrenaline. However, it is possible that spastic contraction may be reflex. When using low-quality local anesthetics, toxic-allergic damage to the optic nerve fibers is possible. Timely provision of emergency care for the spastic genesis of pathology contributes to the rapid regression of ophthalmic symptoms.
With conduction anesthesia in the area of innervation of the anterior and posterior lattice nerves, the optic nerve can be damaged with the tip of a needle. The growth of hematoma potentiates the compression of nerve fibers. An important role is assigned to an acute violation of arterial circulation, which is associated with thrombosis, embolism or spasm of the central artery. In the pathogenesis of pathology, ischemia is also present in the area of blood supply to the orbital, posterior ciliary artery or retinal artery. Visual dysfunction in temporal arteritis is caused by trophic disorders in the basin of the vessels feeding the optic nerve.
Patients clearly trace the relationship between the appearance of symptoms and the performance of surgical intervention. When performing surgery on the nasal septum, the first manifestations occur within 10 minutes after novocaine anesthesia. Patients note that after the photopsies, severe pain in the eye socket area increases. Pupils are dilated. Attempts to make movements with the eyeballs are fruitless. It is characterized by numbness of the skin of the forehead and ptosis of the upper eyelid on the side of the lesion. After a few minutes, there is a total decrease in visual acuity.
In some cases, patients describe the symptoms of the disease as lowering the “curtain” or “flap” over the eyes. Pathology often develops spontaneously. The appearance of symptoms may be preceded by exposure to a bright color, a change in body position, intense physical exertion. If the cause of the disease is an embolism of the retinal vessels, then the clinical picture is represented by a painless rapidly progressive visual dysfunction. Partially vision is preserved only in the presence of an additional cilioretinal artery supplying blood to the central area of the inner shell of the eye.
The diagnosis is based on anamnestic information, the results of an objective examination and specific diagnostic methods. As a rule, there is a relationship between the occurrence of symptoms and the conduct of invasive interventions. An objective examination reveals persistent mydriasis. Specific research methods include:
- Visometry. On the affected side, visual acuity is 0. When examining the other eye, visual dysfunction is not determined. Timely medical care allows you to restore visual acuity within 2 hours.
- Ophthalmoscopy. When examining the fundus, the optic nerve disc has a pale pink color. The boundaries of OND are clear. The vessels are sharply narrowed. With embolism of the central artery, the retina is pale due to vascular spasm.
- Biomicroscopy of the eye. When examining the anterior segment of the eyeball, dilated pupils are visible. There are no pathological changes on the part of the conjunctiva and cornea. The transparency of the optical media of the eye is preserved.
- Ultrasound of the eyes. With the traumatic genesis of the disease, it is possible to visualize a limited accumulation of blood in the affected area. The length of the sagittal axis of the eyeball does not exceed 27.3 mm. The diameter of the OND is within 2-2.5 mm.
Treatment tactics are determined by the etiology of the disease. If the optic nerve is injured with the formation of a hematoma, surgical intervention is necessary. During the operation, blood clots are evacuated. If the disease is based on spastic vasoconstriction, patients are shown conservative treatment, which is reduced to prescribing:
- Hormonal drugs. Medications are able to eliminate the phenomena of edema in the OND area and stop the secondary inflammatory reaction in the traumatic origin of the pathology. Retrobulbar administration of glucocorticosteroids (prednisone) is recommended.
- Nicotinic acid. It is used to expand small blood vessels and improve microcirculation. Niacin has a weak anticoagulant effect and increases the fibrinolytic activity of the blood.
- Antispasmodics. Medications allow to expand the spasmodic vessels of the retina and to stop the symptoms of acute ischemia. The effectiveness of its use in the treatment of patients with temporal arteritis has been proven.
- Plasma substitutes. Intravenous administration of dextran solution on isotonic sodium chloride solution is shown. The appointment of plasma substitutes is justified if amaurosis fugax has arisen due to incorrect dosage of anesthetics.
- Membrane stabilizing agents. Adenosine is used, which has an anti-ischemic effect. The drug improves hemodynamic parameters and reduces the need for oxygen, has a vasodilatory effect.
Prognosis and prevention
With a spastic origin of the disease, the prognosis for life and working capacity is favorable. In case of injury to the optic nerve, irreversible loss of visual functions is possible. To prevent the development of pathology during surgical intervention on the nasal cavity in persons suffering from myopia, adrenaline is added to the anesthetic in low concentration. Patients at risk of thromboembolic complications need to monitor the parameters of the lipidogram and the general blood test. Antiplatelet and anti-lipid medications should be taken. Twice a year it is recommended to be examined by an ophthalmologist with mandatory ophthalmoscopy and visometry.