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November 24, 2009
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 Presbyopia Main Article |  Glossary |  Presbyopia Index 

Presbyopia Glossary of Terms

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

Aging: The process of becoming older, a process that is genetically determined and environmentally modulated.
See the entire definition of Aging

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.

Cornea: The clear front window of the eye that transmits and focuses light into the eye.
See the entire definition of Cornea

Disease: Illness or sickness often characterized by typical patient problems (symptoms) and physical findings (signs). Disruption sequence: The events that occur when a fetus that is developing normally is subjected to a destructive agent such as the rubella (German measles) virus.

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.
See the entire definition of Eye

Farsightedness: Medically termed hyperopia; the ability to see distant objects more clearly than close objects.
See the entire definition of Farsightedness

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.
See the entire definition of FDA

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

Keratoplasty: Corneal transplant.
See the entire definition of Keratoplasty

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

Laser surgery: A type of surgery that uses the cutting power of a laser beam to make bloodless cuts in tissue or remove a surface lesion such as a skin tumor. There are a number of different types of lasers that differ in emitted light wavelengths and power ranges and in their ability to clot, cut, or vaporize tissue. Among the commonly used lasers are the pulsed-dye laser, the YAG laser, the CO2 (carbon dioxide) laser, the argon laser, the excimer laser, the KTP laser, and the diode 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.
See the entire definition of Lens

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.

Presbyopia: The loss of the eye's ability to change focus to see near objects. The reasons for this loss of the power of accommodation are not yet fully known. It is conventionally said to be due to the lens becoming less elastic with time.
See the entire definition of Presbyopia

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.

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Progressive: Increasing in scope or severity. Advancing. Going forward. In medicine, a disease that is progressive is going from bad to worse.
See the entire definition of Progressive

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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 Presbyopia Main Article |  Glossary |  Presbyopia Index 




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Presbyopia

What is the structure of the eye?

The eyes are complex sensory organs. About 85% of the total sensory input to our brains originates from our sense of sight, while the other 15% comes from the other four senses of hearing, smell, touch, and taste. The eyes are designed to optimize vision under conditions of varying light. Their location, on the outside of the face, makes them susceptible to trauma, environmental chemicals and particles, and infectious agents. The eyelids and the position of the eye within the bony orbital cavity are the major protective mechanism for the eye.

The eye itself has the shape of a sphere measuring about 1 inch in diameter. It consists of a clear, transparent dome at the front (the cornea) that is surrounded by the white of the eyeball (the sclera). The iris of the eye is the circular, colored portion within the eye, and behind the cornea, and the pupil is the central opening within the iris. Behind the iris and pupil is the e...

Read the Eye Care article »










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