ION - Ischemic optic neuropathy: Description, Causes and Risk Factors:ICD-10: H47.0.Abbreviation: ION.ION - Ischemic optic neuropathy is a relatively sudden loss of vision due to decreased or interrupted blood flow to the eye's optic nerve. In order for you to see, the optic nerve carries impulses from the eye to the brain, where they are interpreted as images. Without a healthy, functioning optic nerve, vision would not be possible.Ischemic optic neuropathy is occurs most commonly in people over age 55 and causes mild to complete vision impairment. There are two forms: arteritic, associated with giant-cell arteritis (an inflammatory disorder of the arteries that typically affects the temporal arteries) and nonarteritic, which correlates with cardiovascular disease, hypertension (high blood pressure), hypotension (low blood pressure), atherosclerosis, diabetes, and rheumatoid arthritis (RA).Ischemic optic neuropathy is also an uncommon complication of a variety of procedures including CABG (coronary artery bypass graft), cholecystectomy, radical neck dissection, spinal fusion, endoscopic sinus surgery, and liposuction.Ischemic optic neuropathy can be divided into anterior and posterior forms. In anterior ischemic optic neuropathy, the insult is thought to be caused by occlusion of the short posterior ciliary arteries, with resultant ischemia of the optic nerve head. Posterior ION is caused by occlusion of the circumferential pial branches of the ophthalmic artery, which places the retrolaminar optic nerve at an increased risk of ischemia during long procedures, particularly those characterized by long periods of hypotension and large amounts of blood loss.Risk Factors May Include:Older age.
Glaucoma (high intraocular pressure).
High blood pressure.
Arterial disease (clogged arteries).
Temporal arteritis (inflammation of certain arteries, including those to the eye).
Symptoms:Before ION occurs, some people experience transient ischemic attacks (TIA)—a temporaryreduction of blood flow to the optic nerve. During the attack, vision becomes dark for a fewseconds or minutes and then returns to normal. TIAs are warning signs that a completeblockage of blood flow to the eye may occur.Other symptoms may include:Sudden loss of the central vision.
Visual acuity is reduced in most cases, but varies from a mild reduction to no light perception.
Contrast sensitivity and color vision are impaired in almost all cases.
Diagnosis:An ophthalmologist may be able to detectwarning signs of ION during an eye examination. The examination may involve dilating(temporarily opening) the pupil with eyedrops in order to check for swelling of the optic nerveor inflammation of arteries in the eye. Tests for intraocular pressure and glaucoma may beperformed, as well as tests of your side vision.Tests may include:CT scan.
Serologic test for syphilis.
Treatment:In most cases of ischemic optic neuropathy, there is no proven treatment to improve vision. However, the use of low-vision devices and techniques — including large print materials, bright lighting, high contrast materials, and magnifying devices — can help you continue to perform many of your daily activities independently. Because of the conditions associated with ischemic optic neuropathy (e.g., high blood pressure, clogged arteries, migraines), follow-up with your primary care physician or referral to a specialist is usually recommended as part of treatment. When the ischemic optic neuropathy affects only one eye, the person can make adaptations and adjustments to accommodate the vision impairment that do not necessarily require substantial changes in lifestyle. Most people can still read, work, and perform other functions of daily living with visual acuity in only one eye. Ischemic optic neuropathy that involves both eyes can significantly affect lifestyle.Treatment for arteritic ischemic optic neuropathy is corticosteroid medications to reduce the inflammation. Vision loss, however, is irreversible. There are no effective treatments for the nonarteritic form, which does not appear to improve with corticosteroids. Lifestyle modifications such as smoking cessation improve circulation in general with the presumption that such improvement also affects optic structures. Aspirin therapy, such as prescribed as a prophylactic measure for heart attack and stroke, may have a preventive effect with the arteritic form. It is especially important to manage underlying health conditions that affect circulation, such as hypertension and diabetes.If ischemic optic neuropathy is caused by a condition known as temporal arteritis, patients have a very high chance of the other eye being affected unless treated with steroid tablets (cortisone). The steroids help prevent ischemic optic neuropathy from occurring in the other eye but rarely improve vision lost from ischemic optic neuropathy in the affected eye.NOTE: The above information is educational purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.
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