Optic Neuropathy Ischemic

 

Optic Neuropathy, Ischemic

Definition

Ischemic optic neuropathy (ION) is a sudden loss of central vision, side vision or both due to a decreased or interrupted blood flow to the eye’s optic nerve.

In order to see, the optic nerve carries impulses from the eye to the brain, where they are interpreted as images. The optic nerve is made up of a million tiny, delicate nerve fibers that are like wires. Many blood vessels nourish the optic nerve with blood rich in oxygen and nutrition. Without a healthy, functioning optic nerve, vision would not be possible.

There are two types of ischemic optic neuropathy, depending upon the part of the optic nerve involved:

Anterior ischemic optic neuropathy (AION): AION occurs when blood flow is interrupted to the front (anterior) part of the optic nerve (also called optic nerve head).

Posterior ischemic optic neuropathy (PION): PION is much less common and is a result of ischemia of the back (posterior) part of the optic nerve, located some distance behind the eyeball.

Most cases of ischemic optic neuropathy are a type of AION.

Source : AAO 

 

Organ

 

 

Symptoms

With arteritic AOIN, the majority of people have giant cell arteritis (GCA). This condition may cause symptoms before vision loss, such as overall fatigue, fever, pain in the temples, neck pain, pain when chewing, and scalp pain. A key visual symptom with arteritic AION is temporary blurring or loss of vision before vision loss is permanent.

With nonarteritic anterior ischemic optic neuropathy (NAION) — the most common form of ION — the symptoms are usually sudden, painless vision loss in one eye, with your vision perhaps appearing cloudy or blurry. Usually these symptoms are noticed first when you wake up.

Source : AAO 

 

Frequency

United States

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. 

 

International

In the nonarteritic group, incidence is higher in whites and uncommon in other races. The countries with the highest incidence of arteritic AION are the Scandinavian countries (ie, Norway, Denmark, Sweden), followed by Germany. The arteritic form is not as well recognized in non-whites. In the future, genetic evidence may help to explain this incidence. 

 

Race

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.

A past misconception was that black patients did not succumb to GCA. However, numerous documented cases of GCA in blacks are noted; GCA in black patients is not uncommon. 

 

Sex

Females dominate the incidence in both forms of AION, but only slightly in the nonarteritic form (1.2:1) compared with the arteritic type (2:1). 

 

Age

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. 

Source : Emedicine 

 

Causes

NAION is caused by a sudden decrease in circulation of blood in the arteries supplying the optic nerve. This can be due to a temporary decrease in blood pressure, caused by a variety of different factors. Generally, NAION has less of an impact on visual outcome than the arteritic form (AION).

Some of the common diseases and conditions which can put a patient at higher risk for NAION are:

  • Diabetes mellitus;
  • Rheumatoid arthritis;
  • Herpes zoster;
  • Anemia;
  • Sickle cell trait;
  • Syphilis;
  • Systemic low blood pressure or severe high blood pressure;
  • Gastro-intestinal ulcers;
  • Some cardiac diseases;
  • Vasculitis;
  • Migraine;
  • Type A personality. 

Source : AAO

 

Evolution

Vision lost to optic nerve atrophy cannot be recovered. It is very important to protect the other eye.

Source : Medline Plus 

 

Prevention

Many causes of optic nerve atrophy cannot be prevented.

Prevention steps include:

  • Older adults should have their health care provider carefully manage their blood pressure.
  • Use standard safety precautions to prevent injuries to the face. Most facial injuries are the result of car accidents. Wearing seat belts may help prevent these injuries.
  • Schedule a routine annual eye exam to check for glaucoma.
  • Never drink home-brewed alcohol and forms of alcohol that are not intended for drinking. Methanol, which is found in home-brewed alcohol, can cause optic nerve atrophy in both eyes.

Source : Medline Plus  

 

Diagnosis

If you experience sudden vision loss, it is important that you seek immediate medical attention. Your ophthalmologist will conduct a detailed eye examination to determine if your symptoms are related to ischemic optic neuropathy, and if so, what form of ION is present. Your ophthalmologist will check your visual acuity and measure your eye pressure, as well as use dilating eye drops to conduct a dilated eye examination to look for signs of damage to the optic nerve.

If your ophthalmologist suspects arteritic AION — the more dangerous form of AION — he or she may use a diagnostic test called fluorescein angiography, in which a dye is injected and a series of rapid photographs are taken, to help confirm the blockage of blood flow to the optic nerve.

Your ophthalmologist may also order additional tests to rule out giant cell arteritis (GCA), which is often associated with arteritic AOIN, including blood work and biopsies of arteries in the temple area of the head.

Source : AAO

 

 

Treatment

At this time, there is no proven effective treatment for nonarteritic anterior ischemic optic neuropathy (NAION). Sometimes, corticosteroids may be given to help reduce the inflammation associated with the condition, but the effectiveness of this treatment option is still inconclusive.

Treating the underlying causes of cardiovascular disease, a risk factor for NAION, may help control NAION and prevent further vision loss.

For arteritic AION — the more dangerous form of ION — corticosteroids are given to protect the non-affected eye.

For anyone with vision loss from ischemic optic neuropathy, low vision aids and strategies can be helpful.

Source : AAO 

 

 

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