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Ischemic optic neuropathy is an eye disorder that is most commonly seen in people over the age of 50. It is characterized by mild to severe vision loss that is usually painless and worse in one eye than in the other. Vision problems occur when the optic nerve does not receive a steady supply of new, oxygen-rich blood because of inflammation or damage in nearby blood vessels. Ischemic optic neuropathy may or may not be a sign of a very serious underlying health problem called giant cell arteritis, so it is important to visit a doctor at the first signs of worsening vision problems to receive an accurate diagnosis. Most patients are able to regain at least some of their vision with prescription drugs.
The majority of ischemic optic neuropathy cases are related to problems with the anterior section of the optic nerve, the part closest to the eye that is also called the optic disc. The disc collects information from millions of tiny nerve endings in the eye and transmits signals to the brain. In order to work properly, it requires a constant supply of oxygenated blood. If the blood vessels leading to the disc are weak or damaged, the nerve becomes less effective at relaying signals. As a result, vision acuity and light perception are diminished.
The cause of ischemic optic neuropathy is not always clear. Many patients have underlying diseases that increase their risk of blood vessel problems and optic disc damage, such as diabetes, arthritis, high cholesterol, high blood pressure, and heart disease. Problems occur when blood circulation to the eye is poor, leading to a sudden, sharp drop in ocular blood pressure and optic disc swelling. Giant cell arteritis is a rare but severe potential cause that induces blood vessel inflammation throughout the head and neck, including delicate vessels in the eyes.
Most cases that do not involve arteritis are painless. Vision impairment tends to progress quickly, sometimes in just a few days or even hours. Some people wake up from a night's sleep to find they cannot see well or at all out of one eye. It also is common for a person to lose the ability to detect subtle shades of color, depth, and light brightness. Vision may become very spotty or blurry as well. If arteritis is present, a person may have additional symptoms such as fever, head and neck pain, and fatigue.
An ophthalmologist can diagnose ischemic optic neuropathy with a clinical examination. A specialized microscope is used to view the optic disc and surrounding blood vessels to look for signs of inflammation. If a problem is discovered, blood tests are needed to confirm or rule out arteritis. Treatment decisions are made based on the underlying causes, when they can be discovered.
Ischemic optic neuropathy is usually treated with oral or injected steroids to relieve acute inflammation. Underlying factors such as diabetes or high cholesterol are treated accordingly with medications or surgery. Arteritis may require a very long course of anti-inflammatory drugs and medications that suppress the immune system. The outlook can vary, but a majority of people who receive prompt treatment start seeing better within a few days.