Anterior ischemic optic neuropathy (AION) is an acute blockage of the artery that supplies the optic nerve. This eye condition is also known as ocular infarction.
What is anterior ischemic optic neuropathy?
Anterior ischemic optic neuropathy (AION) is also known as optic malacia, apoplexia papillae, or ocular infarction. In this eye disease, there is a disturbance of blood flow to the optic nerve head. In most cases, this is caused by an acute occlusion or blockage of the ophthalmic artery, which is located in the Zinn-Haller vascular cortex and is responsible for supplying the optic nerve. Due to the lack of blood supply, the optic nerve head can no longer be adequately supplied with nutrients and oxygen. This circumstance in turn results in the death of functional nerve tissue. Therefore, anterior ischemic optic neuropathy is considered an ophthalmic emergency. The abrupt onset of decreased blood flow to the optic nerve head causes a rapidly progressive deterioration of vision. Thus, the nerve cells are often irreversibly affected by the undersupply of neuronal tissue. This effect can be compared to an ischemic stroke. Without appropriate treatment, the patient is at risk of a significant reduction in vision. In the worst case, blindness is even possible. Thus, no new nerve cells are generated from the dead neurons. The average age for the onset of anterior ischemic optic neuropathy is 61 years. In the case of non-inflammatory AION, the adjacent eye is also damaged in about 19 percent of all patients. In the inflammatory form, damage to the neighboring eye is imminent after only a few days. In such cases, the affected persons are usually over 70 years old. Recurrence in the same eye is rare.
Causes
In the context of anterior ischemic optic neuropathy, physicians distinguish between inflammatory and noninflammatory AION. In most affected individuals, anterior ischemic optic neuropathy develops as a result of an embolism. This often forms as a result of a pronounced endocarditis or previously occurring atrial fibrillation. The resulting blood clot can travel through the blood vessels to the coronary artery of Zinn-Haller. Once there, there is a significant risk of blockage of the supplying ophthalmic artery. Another possible cause of anterior ischemic optic neuropathy is advanced arteriosclerosis. This is primarily seen in people who suffer from diabetes mellitus. Inflammatory processes, on the other hand, rarely lead to the development of the eye disease. Other possible causes are generalized vasculitis (inflammation of the blood vessels) and temporal arteritis. About 90 percent of all AION patients also suffer from a cardiovascular disease such as high blood pressure or diabetes. A possible risk factor for AION is farsightedness. Occasionally, anterior ischemic optic neuropathy is also caused by surgery. Probable triggers in such cases are anemia as well as a drop in blood pressure.
Symptoms, complaints, and signs
In most cases, the symptoms and complaints of this condition occur very suddenly and unexpectedly. In this case, the affected person suffers from a severe loss of vision, which occurs relatively suddenly. Nearsightedness or farsightedness develops, so that the patient is dependent on visual aids in his or her daily life. In very severe cases, the disease can also lead to complete blindness. This is no longer reversible and cannot be treated. Furthermore, the eye no longer reacts or reacts only very sluggishly to incident light, so that the pupil hardly changes. However, the healthy eye is not affected by these symptoms. It is not necessary that both eyes are affected by the loss of vision, often the symptoms only occur in one eye. However, this still leads to severe restrictions in everyday life and limitations in the field of vision. The risk of stroke or heart attack is also significantly increased with this disease, so that patients are dependent on regular examinations in their lives.Loss of vision can further lead to severe psychological discomfort or even depression.
Diagnosis and course
If the presence of anterior ischemic optic neuropathy is suspected, a physician must be consulted immediately. Thus, eye damage that is irreparable is imminent after only a few hours. At the ophthalmologist‘s office, a thorough examination is performed, including ocular microscopy. A possible indication of parallel edema is an optic disc that is abnormally blurred. In addition, the optic disc is often conspicuous by pallor. This pallor is a criterion for poor perfusion. Furthermore, fine hemorrhages can be detected in the optic disc region. Frequently, there are restrictions of the visual field. With the aid of fluorescence angiography, the physician determines the presence of reduced blood flow. If an inflammatory cause of AION is suspected, an arterial biopsy of the temporal artery is performed to examine the affected tissue. Investigations such as a magnetic resonance imaging (MRI) scan of the head, as well as a blood sedimentation reaction and the CRP procedure, are also considered useful. Based on causative disease or risk factors, further testing by a neurologist or internist is usually required. Even with a quick start of medical treatment, the previous vision usually cannot be restored. In the case of central retinal artery occlusion, therapy can restore vision in only one to eight percent of all affected individuals. In addition, AION patients are at increased risk of heart attack or stroke. About 18 percent of all affected individuals suffer from diabetic neuropathy as the disease progresses.
Complications
Anterior ischemic optic neuropathy (AION), an embolism in the eye, can lead to severe limitation or even loss of vision in the affected eye as well as limitation of the visual field due to optic nerve damage. Because anterior ischemic optic neuropathy is an emergency, prompt diagnosis and prompt treatment are critical. Whether this is an inflammatory or noninflammatory form also plays an important role in the likelihood of complications occurring. Causes of anterior ischemic optic neuropathy must be adequately treated. Although damage already done to the eye cannot be reversed by treatment, the occurrence of further damage can be reduced or prevented. Also, AION that has been undergone and not treated or not treated in a timely manner carries an increased risk of infarction to major organs such as the heart and brain. If the AION is not treated and sources of danger are not eliminated, further damage to the affected eye, including blindness, may occur, as well as the occurrence of an AION in the other eye. Eliminating risk factors and avoiding triggering medications can avert or reduce the complications of anterior ischemic optic neuropathy.
When should you see a doctor?
Anterior ischemic optic neuropathy (AION) is principally an emergency situation that requires prompt care, preferably in an eye clinic. Alternatively, treatment can be provided in a neurological or internal medicine clinic that has experience and equipment for locating and dissolving a blood clot (thrombus) in the vascular system of the head. The goal of rapid emergency care is to locate the causative thrombus in the optic artery to dissolve it as quickly as possible. The approximately one million gossamer nerve fibers that leave the eye bundled through the optic disc are very sensitive to a lack of oxygen supply. If no professional care is possible within hours, irreversible blindness of the affected eye is imminent. If it takes a long time to get to the clinic, or if neither a specialist nor a clinic can be visited, the patient should be placed flat with the leg in an elevated position to improve blood flow through the optic artery despite possible occlusion of the optic nerve artery. In addition, the eyeball can be lightly massaged, which in some cases has resulted in unblocking of the arterial blockage, restoring at least a partial supply to the optic disc.If some sort of spontaneous recovery occurs during transport to the clinic because the blood supply to the optic disc has returned to normal, it is important to visit the clinic anyway because there is an increased risk of stroke and preventive measures should be initiated, usually consisting of anticoagulation with medication.
Treatment and therapy
Treatment of AION is usually performed in a hospital setting. However, a uniform therapeutic regimen has not yet been established. Thus, various methods are used, all of which are intended to improve blood flow to the eye. These include massaging the eyeball, placing the patient in a flat position, administering infusions that thin the blood, and administering anticoagulant drugs such as acetylsalicylic acid and heparin. Furthermore, it is important to treat the causative underlying diseases. As a rule, the patient is given drugs to promote circulation. These are usually calcium antagonists. If inflammation is the cause of the AION, high-dose cortisone treatment is given.
Outlook and prognosis
The outlook for recovery in anterior ischemic optic neuropathy depends on the severity of the circulatory disturbance. In mild cases and when blood flow is interrupted for a short time, few optic nerve cells are damaged or destroyed. Therefore, there is no severe deterioration of vision. Often, a reduction of vision in everyday life can be compensated or improved by the use of visual aids. In the case of a prolonged disturbance of the blood flow, damage to the nerve cord occurs that cannot be repaired. The impairments remain permanently or can only be minimally improved with the available therapy options. In only about 40% of patients with anterior ischemic optic neuropathy is relief of symptoms possible. However, this is of a minor degree. If the cardiovascular risk factors can be found and reduced, there is the possibility of an improvement in vision during the healing process. Other patients suffer lifelong impairments that cannot be corrected with current medical options. In addition to the prognosis of the underlying disease, there is an increased risk of suffering a mental disorder due to the loss of sight. Therapy for mental problems is lengthy. The prognosis outlook is individual for mental impairment. The symptoms may persist unabated for years.
Prevention
Specific preventive measures against AION are not known. Prevention of the precipitating underlying diseases is recommended.
Follow-up care
In most cases of this disease, the options for follow-up care are relatively limited. In this case, the patient is primarily dependent on treatment by a medical professional for complete relief of symptoms. If left untreated, the disease can in the worst case lead to complete blindness of the affected person. The earlier the symptoms of the disease are recognized, the better the further course of the disease. Since the disease is still largely unexplored at the present time, no direct treatment can be carried out. The affected person is dependent on massages of the eye, which he can also carry out himself in his own home. Furthermore, medications can be used to thin the blood and thus alleviate the symptoms. However, a complete cure cannot be guaranteed. Those affected are primarily dependent on taking the medication regularly, whereby possible interactions with other medications must also be taken into account. The administration of cortisone can also alleviate the symptoms. Frequently, the support of family and one’s own friends also has a very positive effect on the further course of the disease and can prevent psychological complaints.
What you can do yourself
AION is often based on a civilization disease such as arteriosclerosis, high blood pressure or diabetes mellitus. Since the yellow spot at the back of the eye continuously has the highest metabolic activity in the human body, cardiovascular diseases can often be seen at the back of the eye – this is also how the underlying disease shows up as a reduced supply to the optic nerve in an AION.It is therefore important that the underlying disease is carefully controlled, monitored and adjusted to minimize the effects on the cardiovascular system. Basically, if possible, prevention starts a few decades earlier with a healthy lifestyle, exercise and sport. An attempt should be made to keep the body in balance with as much healthy living as possible. Ophthalmological checkups should also be done. Even if the vision of the affected eye cannot be restored, it is still important to watch that eye and the other eye. Over time, the eye and brain will more or less learn to compensate for the loss of function in the affected eye. If the visual acuity in the better eye is 30 percent due to other eye diseases, magnifying vision aids can be used to help out. These are available for near and far vision. These aids are available on prescription from an optician or specialized low-vision optician. The home can be designed to provide contrast, including when setting the table or preparing food or using the dishes. This is where the scope of self-help associations such as DBSV or Pro Retina begins. Affected people with various eye diseases have joined together in these associations to offer psychosocial counseling and practical life assistance on a voluntary basis – at eye level.
