Ischemic optic neuropathy anterior

NAION, as a rule, appears suddenly and immediately after awakening. Patients notice visual impairment in one eye . The vision in this eye is hidden by a dark shadow, often only the upper or lower half of the view is visible, as a rule, the area closer to the nose. It does not cause pain. About 6 months after a heart attack in 42.7% of patients, visual acuity improves by 3 or more lines of the Snellen table (a table with smaller letters on each bottom line). In addition, in 12.4% of patients, vision deteriorates by 3 lines or more. Damage to the other eye occurs from approximately 15% to 20% of patients with NAION for 5 years. ^[2] Fortunately, it cannot be very destructive, since visual acuity can only remain moderately impaired. In addition, in most cases, NAION involves the loss of only half of the visual field (upper or lower half of the visual field, but not both). Several cases of NAION have caused nearly complete loss of vision.

An arteritic AION is similar in appearance to a non-arteritic AION and patients aged 50 and older with a diagnosis of NAION should be tested to rule out AAION (symptoms: painful jaw muscle cramps, weak scalp, unintentional weight loss, fatigue, myalgia, and loss of appetite). In addition, patients with NAION over the age of 75 should often do a blood test anyway.

It is believed that the frequency of AION is about 8000 / year in the United States. ^[3]

Using the injury mechanism for NAION is quite controversial. However, experts in this area have reached a consensus that most cases represent two major risk factors. Firstly, the predisposition is in the form of a type of optical disk shape. The optical disk is the place where axons from ganglion cells of the retina gather into the optic nerve. The optic nerve is a bundle of axons that carry visual signals from the eyes to the brain . This optic nerve must penetrate through the wall of the eye, and the opening for its placement, as a rule, is 20-30% larger than the diameter of the nerve. In some patients, the optic nerve is almost the same diameter as the opening in the back of the eye, and the optic nerve head appears “full” when viewed with ophthalmoscopy . A filled disk also qualifies as a “risk disk”. Despite the risk factor, the vast majority of people with full discs do not experience NAION.

The second major risk factor is more common cardiovascular risk factors. The most common are diabetes , hypertension and high cholesterol . While these factors predispose to the development of NAION in a patient, the most common observed factor is a sharp drop in blood pressure during sleep (nocturnal arterial hypotension) - therefore, at least 75% of patients first experience loss of vision when they wake from sleep. These vascular risk factors lead to ischemia (poor blood supply) in part of the optic disc. The disk then swells and overflows the opening of the optic nerve disk, which leads to compression and increased ischemia.

Since both eyes tend to have a similar appearance, an ophthalmologist or an ophthalmologist must look at a good eye to assess anatomical predisposition. An eye without damage has a 14.7% risk of NAION for five years. ^[four]

A number of studies focus on the use of Viagra with NAION. ^{[5] [6] [7] [8] [9] [10]}

It was believed that there was no recognized treatment capable of repairing the damage caused by NAION. However, a recent large study showed that if patients were treated with large doses of corticosteroids in the early stages of NAION in eyes with an initial visual acuity of 20/70 or worse, detected within 2 weeks from the onset of the disease, there was an improvement in visual acuity by 70% in the group receiving treatment compared with 41% in the control group. ^[11] This study and a natural study of the history of NAION studies (Ophthalmology 2008; 115 :. 298-305) showed that visual acuity can improve up to 6 months, and not after that. To minimize the risk of further visual impairment in the paired eye or other eye, it is important to reduce risk factors. Common sense dictates that one should try to control cardiovascular risk factors for many reasons, including to protect against this second eye. In case of sudden loss of vision, an ophthalmic consultation is necessary. If NAION is suspected, then a neurophthalmologist consultation will be required .

There are many studies currently looking for ways to protect the nerve (neuroprotection), or even causing new fibers in the optic nerve. ^{[12] [13] [14] [15] [16]} There is no ongoing clinical trial for the treatment of NAION. There is still no evidence that the so-called neuroprotective agents give any positive effect in NAION.

In addition to such research, patents were filed for Pfizer, University of Southern California, Otsuka Pharmaceutical, and other individual inventors for innovations related to the treatment of anterior ischemic optic neuropathy. ^[17]