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 Electroretinography Main Article |  Glossary |  Electroretinography Index 

Electroretinography Glossary of Terms

The following are health and medical definitions of terms that appear in the Electroretinography article.

Abnormal: Not normal. Deviating from the usual structure, position, condition, or behavior. In referring to a growth, abnormal may mean that it is cancerous or premalignant (likely to become cancer ).
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Acquired: Anything that is not present at birth but develops some time later. In medicine, the word "acquired" implies "new" or "added." An acquired condition is "new" in the sense that it is not genetic (inherited) and "added" in the sense that was not present at birth.
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Anesthetic: A substance that causes lack of feeling or awareness. A local anesthetic causes loss of feeling in a part of the body. A general anesthetic puts the person to sleep.

Arteriosclerosis: Hardening and thickening of the walls of the arteries. Arteriosclerosis can occur because of fatty deposits on the inner lining of arteries (atherosclerosis), calcification of the wall of the arteries, or thickening of the muscular wall of the arteries from chronically elevated blood pressure (hypertension).

Cell: The basic structural and functional unit in people and all living things. Each cell is a small container of chemicals and water wrapped in a membrane .
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Cornea: The clear front window of the eye that transmits and focuses light into the eye.
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Electroretinography : Abbreviated ERG. A test in which the electrical potentials generated by the retina of the eye are measured when the retina is stimulated by light.
See the entire definition of Electroretinography

ERG: Electroretinography.

Excess iron: Iron overload can damage the heart, liver, gonads and other organs.
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Eye: The organ of sight. The eye has a number of components. These components include but are not limited to the cornea, iris, pupil, lens, retina, macula, optic nerve, choroid and vitreous.
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Eyelash: One of the familiar stiff hairs that project from the margin of the eyelid.
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Giant cell arteritis: A serious disease characterized by inflammation of the walls of the blood vessels (vasculitis). The vessels affected by the inflammation are the arteries (hence the name "arteritis"). The age of affected patients is usually over 50 years of age. Giant cell arteritis can lead to blindness and/or stroke. It is detected by a biopsy of an artery. Giant cell arteritis is treated with high dose cortisone-related medications. Also called temporal arteritis or cranial arteritis.

Indicate: In medicine, to make a treatment or procedure advisable because of a particular condition or circumstance. For example, certain medications are indicated for the treatment of hypertension during pregnancy while others are contraindicated.

Injure: To harm, hurt, or wound. The word injure may be in physical or emotional sense. Treadmill machines may injure anyone who gets on one. Sexual molestation injures children. From the Latin injuria meaning injury.

Iron: An essential mineral. Iron is necessary for the transport of oxygen (via hemoglobin in red blood cells) and for oxidation by cells (via cytochrome). Deficiency of iron is a common cause of anemia. Food sources of iron include meat, poultry, eggs, vegetables and cereals (especially those fortified with iron). According to the National Academy of Sciences, the Recommended Dietary Allowances of iron are 15 milligrams per day for women and 10 milligrams per day for men. Iron overload can damage the heart, liver, gonads and other organs. Iron overload is a particular risk in people who may have certain genetic conditions (hemochromatosis) sometimes without knowing it and also in people receiving recurrent blood transfusions. Iron supplements meant for adults (such as pregnant women) are a major cause of poisoning in children.

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Metabolic: Relating to metabolism, the whole range of biochemical processes that occur within us (or any living organism). Metabolism consists of anabolism (the buildup of substances) and catabolism (the breakdown of substances).
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Numb: Numb, or numbness is a loss of the sensation of feeling in an area of the body. Numbness results from damage to, or impaired function of, the nerves that supply the affected area. The function of the nerves may be impaired by numerous causes including some chronic diseases ( diabetes mellitus , thyroid disease, migraine ), trauma , toxins, decreased blood supply due to atherosclerosis or other conditions, electrolyte imbalances, and pressure on the spinal nerves from herniated discs or other diseases of the spine .
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Retina: The retina is the nerve layer that lines the back of the eye, senses light, and creates impulses that travel through the optic nerve to the brain. There is a small area, called the macula, in the retina that contains special light-sensitive cells. The macula allows us to see fine details clearly.
See the entire definition of Retina

Retinal: Pertaining to the retina , the extraordinary layer of neurons (nerve cells) that line the back of the eye, which can sense light and create impulses capable of voyaging through the optic nerve to the brain where the impulses are recognized as an image.
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Sense: In biology and medicine, the faculty of sensory reception. The ability to convey specific types of external or internal stimuli to the brain and perceive them. Sensory reception occurs through a process known as transduction in which stimuli are converted into nerve impulses which are relayed to the brain.
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Surgery: The word "surgery" has multiple meanings. It is the branch of medicine concerned with diseases and conditions which require or are amenable to operative procedures. Surgery is the work done by a surgeon. By analogy, the work of an editor wielding his pen as a scalpel is s form of surgery. A surgery in England (and some other countries) is a physician's or dentist's office.
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Vitamin A: Vitamin A is retinol. Carotene compounds (found, for example, in egg yolk, butter and cream) are gradually converted by the body to vitamin A (retinol). A form of vitamin A called retinal is responsible for transmitting light sensation in the retina of the eye.
See the entire definition of Vitamin A

Vitamin A deficiency: A lack of vitamin A.
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 Electroretinography Main Article |  Glossary |  Electroretinography Index 




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  • Usher Syndrome - Learn about usher syndrome, the most genetic common condition that affects hearing and vision. Symptoms include hearing loss, and retinitis pigmentosa.

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Electroretinography

What is Usher syndrome?

Usher syndrome is the most common condition that affects both hearing and vision. A syndrome is a disease or disorder that has more than one feature or symptom. The major symptoms of Usher syndrome are hearing loss and an eye disorder called retinitis pigmentosa, or RP. RP causes night-blindness and a loss of peripheral vision (side vision) through the progressive degeneration of the retina. The retina is a light-sensitive tissue at the back of the eye and is crucial for vision. As RP progresses, the field of vision narrows - a condition known as "tunnel vision" - until only central vision (the ability to see straight ahead) remains. Many people with Usher syndrome also have severe balance problems.

There are three clinical types of Usher syndrome:

  • type 1,
  • type 2, and
  • type 3.

In the United States, types 1 and 2 are the most common types. Together, they...

Read the Usher Syndrome article »



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