Anterior ischemic optic neuropathy

AION is a condition that involves the impairment or complete loss of vision due to damage to the optic nerve from insufficient blood supply. By definition, AION involves the first 1mm segment of the optic disc, the optic head. It is very important because it constitutes one of the major causes of blindness or seriously impaired vision among the middle-aged and elderly population, although no age is spared. AION is divided into two main categories according to its etiologies: NAION and AAION. The presentation at clinical examination of the two types of AION is similar, but differences exist. The biomicroscopic exam shows the color, size of cup (cup-to-disc ratio), sharpness of edge, swelling, hemorrhages, notching in the optic disc and any other pathological abnormalities. In the case of AION the optic disc is swollen and pale. Since this presentation is not specific to this condition, further examination methods have to be used like a perimeter to test the visual field of the patient. AAION occurs in aproximately 20% of patients with GCA and constitutes 5 to 10% of all AION.The pathophysiology of NAION remains unknown but several risk factors and conditions have been shown to increase its incidense. NAION is the most frequent kind of AION and no treatment has been proven really effective until now, while AAION is managed with corticosteroids