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 Cataracts Main Article |  Glossary |  Cataracts Index 

Cataracts Glossary of Terms

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

20/20: See; Twenty-twenty.

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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Actinic: Referring to the ultraviolet (UV) rays from sunlight and UV lamps. Sunburn is an actinic burn. An actinic keratosis is a skin lesion that is the consequence of chronic sun exposure. From the Greek "aktis" meaning "ray."

Aging: The process of becoming older, a process that is genetically determined and environmentally modulated.
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Aluminum: A naturally occurring element that makes up about 8% of the surface of the earth and is always found combined with other elements such as oxygen, silicon, and fluorine. Aluminum is is the most common metallic element in the earth's crust but has no clear biologic role. Everyone is exposed to low levels of aluminum from food, air, and water. Exposure to high levels of aluminum may result in respiratory problems (aluminosis). Inhalation of bauxite (aluminum ore) fumes may cause pulmonary fibrosis . Aluminum in the bloodstream may lead to neurological symptoms and may be fatal.
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Anesthesia: Loss of feeling or awareness. A general anesthetic puts the person to sleep. A local anesthetic causes loss of feeling in a part of the body such as a tooth or an area of skin without affecting consciousness. Regional anesthesia numbs a larger part of the body such as a leg or arm, also without affecting consciousness. The term "conduction anesthesia" encompasses both local and regional anesthetic techniques. Many surgical procedures can be done with conduction anesthesia without significant pain. In many situations, such as a C-section, conduction anesthesia is safer and therefore preferable to general anesthesia. However, there are also many types of surgery in which general anesthesia is clearly appropriate.

Arms: An appendage in anatomy and in clinical trials. See: Arm.

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.
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Blurred vision: Lack of sharpness of vision with, as a result, the inability to see fine detail. Blurred vision can occur when a person who wears corrective lens is without them. Blurred vision can also be an important clue to eye disease.

Capsule: Capsule has many meanings in medicine including the following:

  1. In medicine, a membranous structure that envelops an organ, a joint, tumor, or any other part of the body. It is usually made up of dense collagen-containing connective tissue.
  2. In pharmacy, a solid dosage form in which the drug is enclosed in a hard or soft soluble container, usually of a form of gelatin.
  3. In microbiology, a coat around a microbe, such as a bacterium or fungus.

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Cataract: A clouding of the lens of the eye. The normally clear aspirin-sized lens of the eye starts to become cloudy. The result is much like smearing grease over the lens of a camera. It impairs normal vision.


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Cataract surgery: Removal of the clouded lens (the cataract ) in its entirety by surgery, usually followed by replacement of the lens with an intraocular lens (IOL) made of plastic, silicone, acrylic or other material. The operation typically takes about an hour, is done under local anesthetic only, and does not require hospitalization.


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Contrast: Short for "contrast media." Contrast media are X-ray dyes used to provide contrast, for example, between blood vessels and other tissue.

Cornea: The clear front window of the eye that transmits and focuses light into the eye.
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Corneal: Pertaining to the cornea, the clear front window of the eye that transmits and focuses light into the eye.

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Cut: An area of severed skin. Wash a cut or scrape it with soap and water, and keep it clean and dry. Putting alcohol, hydrogen peroxide, or iodine into a wound can delay healing, and should be avoided. Seek medical care if you think you might need stitches, as delay can increase the rate of wound infection. If the cut results from a puncture wound through the shoe, there is a high risk of infection, and you should see your healthcare professional. Redness, swelling, increased pain, and pus draining from the wound also indicate an infection that requires professional care.

Diabetes: Refers to diabetes mellitus or, less often, to diabetes insipidus . Diabetes mellitus and diabetes insipidus share the name "diabetes" because they are both conditions characterized by excessive urination (polyuria).
See the entire definition of Diabetes

Diagnosis: 1 The nature of a disease ; the identification of an illness. 2 A conclusion or decision reached by diagnosis. The diagnosis is rabies . 3 The identification of any problem. The diagnosis was a plugged IV.
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Enzyme: A protein (or protein-based molecule) that speeds up a chemical reaction in a living organism. An enzyme acts as catalyst for specific chemical reactions , converting a specific set of reactants (called substrates) into specific products. Without enzymes, life as we know it would not exist.
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Enzyme defect: A disorder resulting from a deficiency (or functional abnormality) of an enzyme. In 1902 Archibald Garrod first attributed a disease to an enzyme defect: an inborn error of metabolism. Today, newborns are routinely screened for certain enzyme defects such as PKU (phenylketonuria) and galactosemia, an error in the handling (metabolism) of the sugar galactose.

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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FDA: The Food and Drug Administration, an agency within the U.S. Public Health Service, which is a part of the Department of Health and Human Services.
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Feet: The plural of foot, both an anatomic structure and a unit of measure.
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Food and Drug Administration: The FDA, an agency within the U.S. Public Health Service, which is a part of the Department of Health and Human Services.
See the entire definition of Food and Drug Administration

Glaucoma : A common eye condition in which the fluid pressure inside the eyes rises because of slowed fluid drainage from the eye. If untreated, it may damage the optic nerve and other parts of the eye, causing the loss of vision or even blindness.
See the entire definition of Glaucoma

Health: As officially defined by the World Health Organization, a state of complete physical, mental, and social well-being, not merely the absence of disease or infirmity.

Hospital: It may seem unnecessary to define a "hospital" since everyone knows the nature of a hospital. A hospital began as a charitable institution for the needy, aged, infirm, or young.
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Implant: 1. To embed; to set in firmly. In embryology, the fertilized egg implants in the uterine lining 6 or 7 days after conception (fertilization). In medicine today, many things may be implanted.
2. That which is embedded. For example: lens implants, breast implants, cochlear implants, defibrillator implants, pacemaker implants, etc.

Implantation: The act of setting in firmly.
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Incidence: The frequency with which something, such as a disease, appears in a particular population or area. In disease epidemiology, the incidence is the number of newly diagnosed cases during a specific time period. The incidence is distinct from the prevalence which refers to the number of cases alive on a certain date.
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Incision: A cut. When making an incision, a surgeon is making a cut.

Intraocular: In the eye. The intraocular pressure is the pressure within the eye.

Intraocular lens: An artificial lens made of plastic, silicone, acrylic or other material that is implanted inside the eye during cataract surgery. Abbreviated IOL.
See the entire definition of Intraocular lens

Iris: The iris is the circular, colored curtain of the eye. Its opening forms the pupil. The iris helps regulate the amount of light that enters the eye.
See the entire definition of Iris

Laser: A powerful beam of light that can produce intense heat when focused at close range. Lasers are used in medicine in microsurgery, cauterization, for diagnostic purposes, etc. For example, lasers are employed in microsurgery to cut tissue and remove tissue.
See the entire definition of Laser

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.
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Membrane: A very thin layer of tissue that covers a surface.

Microscope: An optical instrument that augments the power of the eye to see small objects. The name microscope was coined by Johannes Faber (1574-1629) who in 1628 borrowed from the Greek to combined micro-, small with skopein, to view. Although the first microscopes were simple microscopes, most (if not all) optical microscopes today are compound microscopes.

Microscopic: So small it cannot be seen without the aid of microscope. As opposed to macroscopic (large enough to be seen with naked eye). A tiny tumor is microscopic while a big tumor is macroscopic.
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Nail: In medicine, there are two types of nails. One is just a plain old metal nail used to hold 2 or more pieces of bone together, for example, after a fracture. The other type of nail is the horny plate on the end of the finger or toe. Each nail anatomically has a body, lateral nail folds (on the sides), a lunula (the little moon-shaped feature at the base), and a proximal skin fold (at the base).
See the entire definition of Nail

Nerve: A bundle of fibers that uses chemical and electrical signals to transmit sensory and motor information from one body part to another. See: Nervous system.

Operation: Although there are many meanings to the word "operation", in medicine it refers to a surgical procedure.
See the entire definition of Operation

Ophthalmologist: An eye doctor. A physician practicing ophthalmology. An ophthalmologist is an M.D.

Ophthalmology: The art and science of eye medicine.

Ophthalmoscope: A lighted instrument, one of the most important tools of the physician, used to examine the interior of the eye , including the lens , retina and optic nerve .
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Pain: An unpleasant sensation that can range from mild, localized discomfort to agony. Pain has both physical and emotional components. The physical part of pain results from nerve stimulation. Pain may be contained to a discrete area, as in an injury, or it can be more diffuse, as in disorders like fibromyalgia . Pain is mediated by specific nerve fibers that carry the pain impulses to the brain where their conscious appreciation may be modified by many factors.
See the entire definition of Pain

Peripheral: Situated away from the center, as opposed to centrally located.
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Peripheral vision: Side vision. The ability to see objects and movement outside of the direct line of vision. Peripheral vision is the work of the rods, nerve cells located largely outside the macula (the center) of the retina. The rods are also responsible for night vision and low-light vision but are insensitive to color. As opposed to central vision.

Phacoemulsification: A procedure in which the lens clouded by a cataract is broken up by ultrasound, irrigated, and suctioned out. Most cataract surgery today is performed using phacoemulsification. Before the advent of this technique, people with cataracts could expect a 10-day hospital stay followed by a lengthy recovery. Today, it is an outpatient procedure. Instead of making a large incision in the eye and removing the lens, the ophthalmologist can make a tiny one and then insert an ultrasonic tip which, vibrating thousands of times a second, breaks up the cataracts without damaging the surrounding tissue. The remains of the cataract are suctioned out.
See the entire definition of Phacoemulsification

Photokeratitis: A burn of the cornea (the clear front surface of the eye ) by ultraviolet B rays (UVB). Also called radiation keratitis or snowblindness.
See the entire definition of Photokeratitis

Prescription: A physician's order for the preparation and administration of a drug or device for a patient. A prescription has several parts. They include the superscription or heading with the symbol "R" or "Rx", which stands for the word recipe (meaning, in Latin, to take); the inscription, which contains the names and quantities of the ingredients; the subscription or directions for compounding the drug; and the signature which is often preceded by the sign "s" standing for signa (Latin for mark), giving the directions to be marked on the container.

Probe: (1) In surgery, a probe is a slender flexible rod with a blunt end used to explore, for example, an opening to see where it goes. (2) In molecular genetics, a probe is a labeled bit of DNA or RNA used to find its complementary sequence or locate a particular clone like homing in on a needle in a haystack.
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Pupil: The opening of the iris. The pupil may appear to open (dilate) and close (constrict) but it is really the iris that is the prime mover; the pupil is merely the absence of iris. The pupil determines how much light is let into the eye. Both pupils are usually of equal size. If they are not, that is termed anisocoria (from "a-", not + "iso", equal + "kore", pupil = not equal pupils).
See the entire definition of Pupil

Radiation: 1. Rays of energy. Gamma rays and X-rays are two of the types of energy waves often used in medicine. 2. The use of energy waves to diagnose or treat disease. See also: Irradiation.

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

Secondary cataract: See: Cataract, secondary.

Sensitivity: 1. In psychology, the quality of being sensitive. As, for example, sensitivity training, training in small groups to develop a sensitive awareness and understanding of oneself and of ones relationships with others. 2. In disease epidemiology, the ability of a system to detect epidemics and other changes in disease occurrence. 3. In screening for a disease, the proportion of persons with the disease who are correctly identified by a screening test. 4. In the definition of a disease, the proportion of persons with the disease who are correctly identified by defined criteria.

Skin: The skin is the body's outer covering. It protects us against heat and light, injury, and infection. It regulates body temperature and stores water, fat, and vitamin D. Weighing about 6 pounds, the skin is the body's largest organ. It is made up of two main layers; the outer epidermis and the inner dermis.


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Steroid: A general class of chemical substances that are structurally related to one another and share the same chemical skeleton (a tetracyclic cyclopenta[a]phenanthrene skeleton).
See the entire definition of Steroid

Sunburn: Sunburn is an inflammation of the skin that develops in response to exposure to ultraviolet (UV) radiation from the sun or from tanning beds and booths that emit UV radiation . Sunburn is manifested by reddened, painful skin that may develop blisters.
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Surgeon: A physician who treats disease, injury, or deformity by operative or manual methods. A medical doctor specialized in the removal of organs, masses and tumors and in doing other procedures using a knife (scalpel). The definition of a "surgeon" has begun to blur in recent years as surgeons have begun to minimize the cutting, employ new technologies that are "minimally invasive," use scopes, etc.
See the entire definition of Surgeon

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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Trauma: Any injury , whether physically or emotionally inflicted. "Trauma" has both a medical and a psychiatric definition. Medically, "trauma" refers to a serious or critical bodily injury, wound, or shock . This definition is often associated with trauma medicine practiced in emergency rooms and represents a popular view of the term. In psychiatry , "trauma" has assumed a different meaning and refers to an experience that is emotionally painful, distressful, or shocking, which often results in lasting mental and physical effects.
See the entire definition of Trauma

Ultrasound : High-frequency sound waves. Ultrasound waves can be bounced off of tissues using special devices. The echoes are then converted into a picture called a sonogram. Ultrasound imaging, referred to as ultrasonography, allows physicians and patients to get an inside view of soft tissues and body cavities, without using invasive techniques. Ultrasound is often used to examine a fetus during pregnancy. There is no convincing evidence for any danger from ultrasound during pregnancy.
See the entire definition of Ultrasound

Ultraviolet A: One of the three types of invisible light rays (together with ultraviolet B and ultraviolet C) given off by the sun.
See the entire definition of Ultraviolet A

Ultraviolet B: One of the three types of invisible light rays (together with ultraviolet A and ultraviolet C) given off by the sun.
See the entire definition of Ultraviolet B

Ultraviolet radiation: Invisible rays that are part of the energy that comes from the sun. Ultraviolet radiation can burn the skin and cause skin cancer .
See the entire definition of Ultraviolet radiation

UV radiation: Ultraviolet radiation. Invisible rays that are part of the energy that comes from the sun, can burn the skin, and cause skin cancer . UV radiation is made up of three types of rays -- ultraviolet A (UVA), ultraviolet B (UVB), and ultraviolet C (UVC).
See the entire definition of UV radiation

Visual acuity: The clarity or clearness of the vision, a measure of how well a person sees. The ability to distinguish details and shapes of objects; also called central vision.
See the entire definition of Visual acuity

Vital: Necessary to maintain life. Breathing is a vital function.

Voluntary: Done in accordance with the conscious will of the individual. The opposite of involuntary.
See the entire definition of Voluntary

Yttrium: A rare elemental metal. A radioactive form of yttrium is used in radiation therapy and some types of immunotherapy.

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 Cataracts Main Article |  Glossary |  Cataracts Index 






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