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).
Abrasion: An abrasion or "excoriation" is a wearing away of the upper layer of skin as a result of applied friction force. In dentistry an "abrasion" is the wearing away of the tooth substance.
Achromatopsia: An hereditary disorder of sight due to a lack of cone vision - that type of vision provided by the cone photoreceptors in the retina. In the normal eye, there are some 6 million cone photoreceptors; they are located largely in the center of the retina. Lacking cones, persons with achromatopsia have to rely on their rod photoreceptors. There are about 100 million rod photoreceptors which are located mainly around the periphery of the retina. Rods saturate at higher levels of illumination and do not provide color vision or good detail vision. See the entire definition of Achromatopsia
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. See the entire definition of Acquired
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).
Atrophy: Wasting away or diminution. Muscle atrophy is wasting of muscle, decrease in muscle mass. See the entire definition of Atrophy
Blindness: Loss of useful sight. Blindness can be temporary or permanent. Damage to any portion of the eye, the optic nerve, or the area of the brain responsible for vision can lead to blindness. There are numerous (actually, innumerable) causes of blindness. The current politically correct terms for blindness include visually handicapped and visually challenged.
Cataract: A clouding or loss of transparency of the lens in the eye as a result of tissue breakdown and protein clumping. There are many causes of cataracts, including aging, cortisone medication, trauma, diabetes, and other diseases. Cataracts affect most people who live into an old age. Symptoms include double or blurred vision and sensitivity to light and glare. A physician can diagnose cataracts by examining the eyes with a viewing instrument. Sunglasses can help to prevent cataracts. See the entire definition of Cataract
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. See the entire definition of Cell
Choroid: In the eye, a thin vascular layer between the sclera and the retina. The choroid supplies blood to the retina and conducts arteries and nerves to other structures in the eye.
Cone: A type of specialized light-sensitive cell (photoreceptor) in the retina of the eye that provide sharp central vision and color vision. See the entire definition of Cone
Congenital: Present at birth. A condition that is congenital is one that is present at birth. There are numerous uses of "congenital" in medicine. There are, for example, congenital abnormalities. (For more examples, see below.) See the entire definition of Congenital
Congenital stationary night blindness: An inherited eye disorder that is not progressive ("stationary") and principally affects the rod photoreceptors in the retina, impairing night vision. There may also be moderate to high myopia (short sightedness). Under good lighting conditions, there is usually no visual deficit. The disorder is diagnosed by electroretinography. There are several different types of the disorder which are inherited in an autosomal dominant, autosomal recessive, or X-linked recessive manner. The X-linked type affects almost exclusively males and accounts for the predominance of males with congenital stationary night blindness. Children with the disorder may have a fear of the dark.
Cornea: The clear front window of the eye that transmits and focuses light into the eye. See the entire definition of Cornea
Corneal: Pertaining to the cornea, the clear front window of the eye that transmits and focuses light into the eye.
Corneal abrasion: A scratch or scrape on the cornea, the clear front window of the eye that transmits and focuses light into the eye.
Dilating: The widening and opening of the cervix caused by uterine contractions.
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
Excess iron: Iron overload can damage the heart, liver, gonads and other organs. See the entire definition of Excess iron
Eyelash: One of the familiar stiff hairs that project from the margin of the eyelid. See the entire definition of Eyelash
Ganglion: The celebrated 2nd century Greek physician Galen ((c. 130-201 A.D.) who lived and worked in Rome first used the word ganglion to denote a nerve complex. Ganglion still is used to refer to an aggregation of nerve cell bodies. Another use of the word ganglion is for a tendon cyst that most commonly pops up near the wrist. See the entire definition of Ganglion
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.
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.
Juvenile retinoschisis: A genetic disease of the eye characterized by retinoschisis (splitting of the retina) symmetrically involving the macula, the area of the retina responsible for central vision, with onset in the first decade of life, in some cases as early as three months of age. Eye examination shows areas of schisis (splitting of the nerve fiber layer of the retina) in the macula, sometimes giving the impression of a spoke wheel pattern. Schisis of the peripheral retina occurs in half of patients. Visual deterioration often progresses during the first decade or two of life, but visual acuity remains relatively stable after puberty. See the entire definition of Juvenile retinoschisis
Lens: The transparent structure inside the eye that focuses light rays onto the retina (the nerve layer that lines the back of the eye, senses light and creates impulses that go through the optic nerve to the brain). The lens was named after the lentil bean because it resembled it in shape and size. See the entire definition of Lens
Medicaid: State programs of public assistance to persons regardless of age whose income and resources are insufficient to pay for health care. The United States federal government provides matching funds to the state Medicaid programs.
Medicare: The United States government's health insurance program for:
"senior citizens" -- people 65 years of age or older,
certain younger people with specific disabilities, and
people with end-stage renal disease (ESRD) -- permanent kidney failure requiring dialysis or a transplant.
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). See the entire definition of Metabolic
Multifocal: Having to do with two or more foci or arising from two or more places. For example, aortic aneurysm disease is often multifocal and needs total aortic screening for diagnosis.
Night blindness: Impaired vision in dim light and in the dark, due to impaired function of specific vision cells (namely, the rods) in the retina. See the entire definition of Night blindness
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.
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. See the entire definition of Retinal
Retinitis pigmentosa: Any one of a large group of inherited disorders in which abnormalities of the photoreceptors (the rods and cones) in the retina lead to progressive visual loss. People with retinitis pigmentosa (RP) first experience defective dark adaptation ("night blindness"), then constriction of the visual field ("tunnel vision") and eventually loss of central vision. See the entire definition of Retinitis pigmentosa
Retinoschisis: Splitting of the retina. From retina + -schisis (splitting).
Sensation: In medicine and physiology, sensation refers to the registration of an incoming (afferent) nerve impulse in that part of the brain called the sensorium, which is capable of such perception. Therefore, the awareness of a stimulus as a result of its perception by sensory receptors. (Sensory is here synonymous with sensation.) See the entire definition of Sensation
Speculum: An instrument used to widen an opening to look within a passage or a cavity. For example, a speculum may be used to widen the opening of the vagina so that the cervix is more easily visible. Other examples include the nasal speculum to look up into the nostrils and the ear speculum to look within the ear canal at the ear drum. The term "speculum" is the Latin word for mirror.
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. See the entire definition of Surgery
Syndrome: A set of signs and symptoms that tend to occur together and which reflect the presence of a particular disease or an increased chance of developing a particular disease. See the entire definition of Syndrome
Usher syndrome: A genetic disorder characterized by hearing impairment and an eye disorder called retinitis pigmentosa in which vision worsens over time. Some people with Usher syndrome also have balance problems. See the entire definition of Usher syndrome
X-linked: On the X chromosome. "Linked" in genetics does not mean merely associated. An X-linked gene travels with the X chromosome and therefore is part of the X chromosome.
There are three types of Usher (Usher's) syndrome, the most common condition that affects both vision and hearing. The major symptoms of Usher syndrome include retinitis pigmentosa (night-blindness and a loss of peripheral vision), and hearing loss. Usher syndrome is a genetic condition. There is no cure for 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...
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