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Leber Hereditary Optic Neuropathy (LHON)

 Leber Hereditary Optic Neuropathy (LHON)



Overview

Leber hereditary optic neuropathy (LHON) is a genetically inherited disease that causes vision loss. Most people who inherit the condition develop blurred vision that gets progressively worse over a course of about six months. Vision loss may start in one eye and then progress to both eyes several months later. It usually starts in late childhood to early adulthood. Most people with LHON will become legally blind.

Leber hereditary optic neuropathy is also called Leber’s disease. It’s named for Dr. Theodore Leber, who studied the disease. “Hereditary” means that you inherit it, and “optic neuropathy” means it’s a disease that affects your optic nerve. Your optic nerve is what carries visual signals from your eye to your brain so that your brain can “see.” Damage to your optic nerve is one way that you can lose your vision.

The standard version of Leber hereditary optic neuropathy (LHON) only affects your optic nerves, and vision loss is its only symptom. This is the case for the vast majority of people with Leber’s disease. But in rare cases, some people with LHON have additional symptoms that affect other parts of their nervous system, and sometimes their heart. Healthcare providers call this version of the disease “Leber plus.”

Symptoms

Vision loss with LHON is painless and subacute, meaning it progresses over several months. You’re likely to notice changes in your central vision first. That’s what you see when you look straight ahead — what you use to drive, read and recognize faces. Your central vision might start to seem blurry, or you might develop a blind spot in the middle of your field of vision. It might occur in one eye first, then the other.

This will continue to worsen over the following months. You also may begin to lose your color vision — the ability to see certain colors or tell colors apart. Vision loss tends to stabilize within six months to a year of the first symptoms. By this time, most people have a visual acuity of 20/200 or worse, which is legally blind. You’ll still have some light perception, but you’ll need to learn to live with low vision.

People with Leber’s plus can have a variety of symptoms beyond vision loss, including:

Movement disorders, like tremors.

Coordination and balance problems (ataxia).

Cardiac conduction problems, like arrhythmias (irregular heartbeats).

Symptoms of multiple sclerosis (MS), like muscle weakness and fatigue.

Causes

Leber hereditary optic neuropathy is a mitochondrial disease, a genetic disorder that you inherit through the mitochondria in your cells. Mitochondria are the energy generators in your cells. They convert oxygen and nutrients into the energy your cells need to operate. Mitochondrial diseases interfere with this process, leaving a lack of energy in your cells. This can cause some cells to malfunction or die.

When your mitochondria aren’t working right, the parts of your body that rely on mitochondrial energy the most will feel it first. These include parts of your eye, especially your optic nerve. If enough of your mitochondria are defective, these parts won’t have the energy they need to function right. In Leber’s disease, the effect is that your optic nerve deteriorates. This is how LHON causes vision loss.

Risk factors

Researchers don’t know exactly why some people with the gene mutation develop symptoms of LHON and others don’t. Some evidence suggests that physiological stress and environmental toxins may contribute to triggering the onset of symptoms. The theory is that these factors may add to the overall stress on body systems affected by LHON. Over time, they add up until they finally trigger symptoms.

Potential risk factors include:

Smoking.

Alcohol use.

Exposure to environmental toxins.

Systemic illness.

Psychological stress.

Diagnosis

Your eye care specialist will conduct standard eye exams to test your vision and look for the cause of the problem. They might not be able to see anything wrong with your eye or your optic nerve at first. The damage becomes more obvious after the first six months of symptoms. When your provider suspects LHON, they’ll recommend genetic testing to confirm that you have one of the gene mutations involved.

Treatment

There’s no definitive cure for LHON. Idebenone, which is a synthetic form of Coenzyme Q10, is the only FDA-approved medication. In randomized controlled trials, idebenone has been associated with improvements in visual acuity in people with LHON. Other similar medications are currently in trials. Researchers are also studying gene therapy as a possible future treatment for Leber’s disease.

Type of Doctor Department :Ophthalmologist or Neuro-ophthalmologist

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