ophthalmoplegia

When you look at an object, you're using several muscles to move both eyes to focus on it. If you have a problem with the muscles, the eyes don't work properly.

There are many kinds of eye movement disorders. Two common ones are:

• Strabismus - a disorder in which the two eyes don't line up in the same direction. This results in "crossed eyes" or "walleye."
• Nystagmus - fast, uncontrollable movements of the eyes, sometimes called "dancing eyes"

Some eye movement disorders are present at birth. Others develop over time and may be associated with other problems, such as injuries. Treatments include glasses, patches, eye muscle exercises, and surgery. There is no cure for some kinds of eye movement disorders, such as most kinds of nystagmus.

Degenerative nerve diseases affect many of your body's activities, such as balance, movement, talking, breathing, and heart function. Many of these diseases are genetic. Sometimes the cause is a medical condition such as alcoholism, a tumor, or a stroke. Other causes may include toxins, chemicals, and viruses. Sometimes the cause is unknown.

Degenerative nerve diseases include:

• Alzheimer's disease
• Amyotrophic lateral sclerosis
• Friedreich ataxia
• Huntington's disease
• Lewy body disease
• Parkinson's disease
• Spinal muscular atrophy

Degenerative nerve diseases can be serious or life-threatening. It depends on the type. Most of them have no cure. Treatments may help improve symptoms, relieve pain, and increase mobility.

Metabolism is the process your body uses to make energy from the food you eat. Food is made up of proteins, carbohydrates, and fats. Chemicals in your digestive system (enzymes) break the food parts down into sugars and acids, your body's fuel. Your body can use this fuel right away, or it can store the energy in your body tissues. If you have a metabolic disorder, something goes wrong with this process.

Mitochondrial diseases are a group of metabolic disorders. Mitochondria are small structures that produce energy in almost all of your cells. They make it by combining oxygen with the fuel molecules (sugars and fats) that come from your food. When the mitochondria are defective, the cells do not have enough energy. The unused oxygen and fuel molecules build up in the cells and cause damage.

The symptoms of mitochondrial disease can vary. It depends on how many mitochondria are defective, and where they are in the body. Sometimes only one organ, tissue, or cell type is affected. But often the problem affects many of them. Muscle and nerve cells have especially high energy needs, so muscular and neurological problems are common. The diseases range from mild to severe. Some types can be fatal.

Genetic mutations cause these diseases. They usually happen before age 20, and some are more common in infants. There are no cures for these diseases, but treatments may help with symptoms and slow down the disease. They may include physical therapy, vitamins and supplements, special diets, and medicines.