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Volume 1 Published - 14:00 UTC    08:00 EST    10-December-2000      
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Back To Vidyya LASIK Glossary

From Ablate To Vitreous Humor, Words To Know

Eye Anatomy

Ablate in surgery, is to remove.

Ablation zone is the area of tissue that is removed during laser surgery.

Accommodation is the ability of the eye to change its focus from distant objects to near objects.

Acuity is clearness, or sharpness of vision.

Astigmatism is a distortion of the image on the retina usually caused by irregularities in the cornea.

Cornea is the clear front part of your eye.  The cornea is the first part of the eye that bends (or focuses) the light and provides most of the focusing power.

Diopter is the measurement of refractive error.  When used in excimer refractive surgery, diopter is a measurement of the refractive power of the eye.  In LASIK and other refractive procedures, a negative diopter value signifies an eye with myopia and positive diopter value signifies an eye with hyperopia.

Dry Eye is a common condition that occurs when the eyes do not produce enough tears to keep the eye wet and comfortable. Common symptoms of dry eye include feelings of stinging, burning, or scratchiness of the eyes.

Endothelium is the inner layer of cells on the inside surface of the cornea.

Epithelium is the outermost layer of cells of the cornea and is the eye's first defense against infection.

Excimer laser is an ultraviolet laser used in refractive surgery to remove corneal tissue.

Farsightedness is the common term for hyperopia.

FDA is the abbreviation for the Food and Drug Administration. The FDA is the United States government agency responsible for the evaluation and approval of medical devices.

Flap & Zap is a slang term for LASIK.

Ghost Image is a fainter second image of the object you are viewing.

Glare is scatter from bright light that decreases vision.

Halos are rings around lights.

Haze is corneal clouding that causes the sensation of looking through smoke or fog.

Hyperopia is the inability to see near objects more clearly than distant objects.

Inflammation is a tissue's reaction to trauma often associated with pain, heat, redness, swelling, and/or loss of function. Inflammation may be caused by mechanical trauma, infections, bacteria, viruses, immune reactions or other causes.

In Situ means "in place" or not removed.

Iris is the colored ring of tissue suspended behind the cornea and immediately in front of the lens.

Keratectomy is the surgical removal of corneal tissue.

Keratotomy is a surgical incision (cut) of the cornea.

Keratitis is the inflammation of the cornea.

Kerato is the prefix indicating relationship to the cornea.

Keratomileusis is the carving of the cornea formerly done with a lathe and blade and now done with an excimer laser.

Laser is an acronym for light amplification by stimulated emission of radiation. A laser is an instrument that produces a powerful beam of light and can vaporize tissue.

LASIK is the acronym for laser assisted in situ keratomileusis which refers to creating a flap in the cornea with a microkeratome and using a laser to reshape the underlying cornea.

Lens is a part of the eye that provides some focusing power.  The lens is able to change shape allowing the eye to focus at different distances.

Microkeratome is a surgical device that is affixed to the eye by use of a vacuum ring. When secured, a very sharp blade shaves a small amount of the cornea at a predetermined depth.

Monovision is the purposeful adjustment of one eye for near vision and the other eye for distance vision.

Myopia the inability to see distant objects clearly.

Nearsightedness is the common term for myopia.

Ophthalmologist is a medical doctor specializing in the diagnosis and medical or surgical treatment of visual disorders and eye disease.

Optician is an expert in the art and science of making and fitting glasses and may also dispense contact lenses.

Optometrist is a primary eye care provider who diagnoses and manages disorders of the visual system and eye disease.

Overcorrection is a complication of refractive surgery where the expected amount of correction is more than desired and often occurs where healing regresses less vigorously than predicted.

PRK is the acronym for photorefractive keratectomy which is a procedure involving the removal of the surface layer of the cornea (epithelium) by gentle scraping and use of a computer-controlled excimer laser to reshape the stroma.

Presbyopia is part of the normal process of aging. As a person becomes older, one begins to lose the flexibility of the lens of the eye which limits the ability of the eye to change its point of focus from distance to near.

Pupil is what appears as a small black dot in the center of the iris and changes its diameter in response to ambient lighting.

Radial Keratotomy is a surgical procedure designed to correct myopia (nearsightedness) by flattening the cornea and is commonly referred to as RK.

Refraction is a test to determine the best eye glasses or contact lenses to correct a refractive error (myopia, hyperopia, astigmatism) OR the bending of light by the use of a lens or other material.

Refractive Errors are hyperopia, myopia, astigmatism and presbyopia.

Retina is the part of the eye that lines the inside wall of the eye and consists of fine sensory tissue which acts as the film in a camera that captures and transmits images.

Sclera is the tough, white, outer layer (coat) of the eyeball and, with the cornea, protects the entire eyeball.

Snellen Visual Acuity  refers to one of many charts used to measure vision (black and white with an "E" at the top).

Stroma is the thick, middle layer of cells in the cornea.

Undercorrection is a complication of refractive surgery where the expected amount of correction is less than desired and often occurs where healing regresses more vigorously than predicted.

Visual Acuity is simply the clearness of vision or the ability to distinguish details and shapes or objects.

Vitreous Humor is the transparent, colorless mass of gel that lies behind the lens and in front of the retina and fills the center of the eyeball.

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Editor: Susan K. Boyer, RN
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