Eye attacks result from a sudden lack of blood flow to the optic nerve of the eye. Eye attacks, which are usually painless, can develop quite rapidly - sometimes overnight, often with catastrophic consequences to the vision of the individual, such as a sudden and permanent loss of peripheral or central vision in one eye. Irreversible damage can occur as quickly as within the first 90 seconds of the attack. The resulting visual impairment and the degree of severity usually varies from patient to patient but can include loss of the bottom half of the vision and difficulty with light and darkness. Most sufferers do not come forward and report the condition - believing it, instead, to be a problem with their glasses or just a temporary, passing phase.
Early reporting is essential as measures designed to limit further damage are most likely to succeed if intervention occurs within the first several hours. In addition, evidence exists that an attack in the other eye occurs up to 15 % of the time, over the following five years. Currently, a daily dose of aspirin is the only treatment offered, having a potential prophylactic effect on the second eye.
This condition, which is the most common cause of acute optical nerve disease in adults over 50 years of age and is thought to be part of the ageing process. The frequency of the condition is estimated to occur in only a couple of people per thousand, per year. ION is suspected to occur with increased frequency in patients with diabetes, hypertension and other vascular disorders, in addition to occurring frequently in people with small, crowded optic nerves.