processing.... Drugs & Diseases > Ophthalmology Anterior Ischemic Optic Neuropathy (AION) Updated: Feb 16, 2021 Author: Andrew A Dahl, MD, FACS; Chief Editor: Hampton Roy, Sr, MD more...
Share Email Print Feedback Close Facebook Twitter LinkedIn WhatsApp webmd.ads2.defineAd(id: 'ads-pos-421-sfp',pos: 421); Sections Anterior Ischemic Optic Neuropathy (AION) Sections Anterior Ischemic Optic Neuropathy (AION) Overview Background
Pathophysiology Epidemiology Show All Presentation History
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Inpatient & Outpatient Medications Transfer Deterrence/Prevention Complications Prognosis Patient Education Show All Media Gallery References Overview Background Field defects typical of ischemic optic neuropathy were probably first described by Knapp in 1875. Miller and Smith first used the term ischemic optic neuropathy in 1966, and Hayreh later added the term anterior. In 1924, Uhthoff first described severe visual loss, with field defects and swollen optic discs. [1]
Anterior ischemic optic neuropathy (AION) is the most common cause of acute optic neuropathy in older age groups. It may be nonarteritic (nonarteritic anterior ischemic optic neuropathy [NAION]) or arteritic (AAION), the latter being associated with giant cell arteritis (GCA; often termed temporal arteritis). AION is characterized by visual loss associated with optic disc swelling of a pallid nature, sometimes with flame hemorrhages on the swollen disc or nearby neuroretinal layer, and sometimes with nearby cotton-wool exudates. Visual loss is usually sudden or develops over a few days at most and is commonly unilateral, although second eye involvement may occur later, especially in the arteritic form. The visual loss is usually permanent, with some recovery possibly occurring within the first weeks or months. Optic atrophy of varying degrees ensues within the next few weeks as a result of the hypoxic episode and is usually generalized but may be sectorial in NAION.
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Anterior ischemic optic neuropathy (AION) is thought to be an ischemic process affecting the posterior circulation of the globe, principally vessels (ie, short posterior ciliary arteries) supplying the optic nerve at its exit from the eye. Only glial cells support the optic disc at this site, and it is the only portion of the optic nerve in which swelling can occur. More posterior ischemia results in a similar condition, without visible swelling, and is termed posterior ischemic optic neuropathy.
Early observations of optic disc photographs suggested that patients with congenitally smaller discs and having smaller or nonexistent optic nerve cups have an anatomical predisposition for nonarteritic anterior ischemic optic neuropathy (NAION). As an ischemic episode evolves, the swelling compromises circulation within a presumable already more compact disc, with a spiral of ischemia and swelling resulting in further neuronal damage. This type of structural/ischemic spiral is less implicated in the arteritic type of AION, in which the entire ophthalmic arterial circulation to the eye and orbit may be compromised.
Patients with both arteritic and nonarteritic forms of anterior ischemic optic neuropathy (AION) are usually older than 50 years, with females predominating in the arteritic group. The incidence of nonarteritic anterior ischemic optic neuropathy (NAION) is 2.3-10.3 per 100,000 in the United States, and, for the arteritic type, it is 0.36 per 100,000. In the arteritic group, the incidence increases almost exponentially with advanced age. The literature seems to support the notion that whites are affected more commonly than blacks in the nonarteritic group, and people of Scandinavian or European ancestry are the most commonly affected ethnic group in the arteritic type.
Bilateral visual loss is more common in the arteritic form of the disease, especially if treatment is delayed, and approximates 50% in some earlier series. By contrast, bilateral visual loss may be seen in 12-19% of nonarteritic anterior ischemic optic neuropathy (NAION), and it usually occurs more sequentially instead of almost simultaneously.
Nonarteritic anterior ischemic optic neuropathy (NAION) is most common in whites (95%); it is less common in blacks (2%), Asians (3%), and Hispanics (1%). The arteritic form of the disease is predominantly described among whites of European descent, particularly Scandinavian and German.
Both disorders are found in older age groups. In the nonarteritic group, age ranges from the late 40s and older. The arteritic group almost always is older than 50 years, with an exponential increase with advanced age (90% of patients are >60 y). Rare cases of AION occur before 40 years, and the differentiation from optic neuritis associated with demyelinating disease is important in this crossover age group.
Abstract:The aim of this study was to perform quantitative optical coherence tomography angiography (OCTA) assessment of arteritic and non-arteritic anterior ischemic optic neuropathies (AION; NAION). The study was designed as an observational, cross-sectional case series. All patients underwent complete ophthalmologic evaluation including LogMAR best-corrected visual acuity (BCVA), structural optical coherence tomography (OCT) and OCTA images, and dye-based angiography. Retinal nerve fiber layer (RNFL) thickness was obtained from structural OCT, and vessel density (VD) and vessel tortuosity (VT) were measured for each optic nerve head vascular plexus. After selecting the quadrants showing visual field defects, measured by Humphrey 30.2 perimetry (Zeiss Meditec, Dublin, CA, USA), we assessed the correlation between the localization of visual field defects and the quadrants showing impairments of RNFL, VD, and VT. Thirty naïve AION patients (15 arteritic AION (AAION) and 15 non-arteritic AION (NAION)) were included. LogMAR BCVA was 0.6 0.2 for AAION and 0.3 0.3 for NAION (p
Average arteriolar and venular blood flow velocities (BFV). Notice the trend of increasing BFV initially after non-arteritic anterior ischemic optic neuropathy, with a decrease in BFV over time thereafter
Limitations of our study include the small sample size and lack of a matched control group for comparison. Although NAION is the most common acute optic neuropathy in patients over age 50, it remains relatively rare, with an incidence of 2.3 to 10.2 cases per 100,000 people age 50 and older. [1, 2, 10, 25, 26] Additionally, delayed presentation to a neuro-ophthalmologist reduces the number of patients affected by NAION evaluated in the acute or subacute phase. Therefore, attaining a large cohort of patients acutely affected by NAION at a single center is difficult.
Alongside PAMM lesions, cotton wool spots, anterior ischemic optic neuropathy, and central retinal artery occlusion, choroidal ischemia is a key angiographic indicator in the diagnosis of GCA. It may be crucial to recognize these typical ischemic chorioretinal signs while diagnosing GCA.
Giant cell arteritis (GCA) is a medium to large vessel granulomatous vasculitis of autoimmune etiology with predilection to the cranial branches of the aortic artery [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32] GCA has multisystem manifestations (new onset temporal headache, jaw claudication, low grade fever), propensity to the elderly population with an average age of onset of 75 years, and a strong female predominance [1, 2]. Since the involvement of the contralateral eye can increase to 60% when left untreated [8], visual loss is the most feared and irreversible complication of GCA, and therapy with a high-dose corticosteroid (and most recently tocilizumab) lowers the incidence of blindness. Vision loss results from either central retinal artery occlusion (CRAO) or posterior ciliary artery (PCA) occlusion manifesting as arteritic anterior ischemic optic neuropathy (A-AION) [10, 12]. The only way to diagnose many ischemic events occurring outside of the papillo-macular area is with intravenous fluorescein angiography, indocyanine angiography or optical coherence tomography angiography (OCTA). These events can involve the choroid (choroidal ischemia) [11, 12] or the retina (cotton-wool spots (CWS) and paracentral acute middle maculopathy (PAMM) [13,14,15,16]. The purpose of this study is to describe such circulatory ischemic events in a case series of GCA using multimodal imaging of the choroidal and retinal circulation. 2ff7e9595c
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