Lasik Glossary
Ablate in surgery, is to remove.
Ablation zone the area of tissue that is removed during laser surgery.
Accommodation the ability of the eye to change its focus from distant objects to near objects.
Acuity clearness, or sharpness of vision.
Astigmatism a distortion of the image on the retina caused by irregularities in the cornea or lens.
Cornea the clear, front part of the eye. The cornea is the first part of the eye that bends (or refracts) the light and provides most of the focusing power.
Diopter the measurement of refractive error. A negative diopter value signifies an eye with myopia and positive diopter value signifies an eye with hyperopia.
Dry Eye Syndrome a common condition that occurs when the eyes do not produce enough tears to keep the eye moist and comfortable. Common symptoms of dry eye include pain, stinging, burning, scratchiness, and intermittent blurring of vision.
Endothelium the inner layer of cells on the inside surface of the cornea.
Epithelium the outermost layer of cells of the cornea and the eye's first defense against infection.
Excimer laser an ultraviolet laser used in refractive surgery to remove corneal tissue.
Farsightedness the common term for hyperopia.
FDA the abbreviation for the Food and Drug Administration. It is the United States governmental agency responsible for the evaluation and approval of medical devices.
Flap & Zap a slang term for LASIK.
Ghost Image a fainter second image of the object you are viewing.
Glare scatter from bright light that decreases vision.
Halos are rings around lights due to optical imperfections in or in front of the eye.
Haze corneal clouding that causes the sensation of looking through smoke or fog.
Higher order aberrations refractive errors, other than nearsightedness, farsightedness, and astigmatism, that cannot be corrected with glasses or contacts.
Hyperopia the inability to see near objects as clearly as distant objects, and the need for accommodation to see distant objects clearly.
Inflammation the body's reaction to trauma, infection, or a foreign substance, often associated with pain, heat, redness, swelling, and/or loss of function.
Informed Consent Form a document disclosing the risks, benefits, and alternatives to a procedure.
In Situ a Latin term meaning "in place" or not removed.
Iris the colored ring of tissue suspended behind the cornea and immediately in front of the lens.
Keratectomy the surgical removal of corneal tissue.
Keratomileusis is the surgical improvement of the refractive state of the cornea performed by lifting up the front surface of the eye by forming a thin hinged flap under which the shape of the cornea is changed by using an excimer laser or other surgical device. A microkeratome is usually used to cut the flap, but a femtosecond laser can also be used to make the flap. Before the advent of the excimer laser, keratomileusis was performed using a cryolathe, which froze thin flaps of corneal tissue and lathe cut them much like one cuts the lens of a pair of glasses. After thawing, these reshaped flaps were placed under the front flap to correct visual improvement. LASIK is currently the only commonly performed keratomileusis procedure.
Keratotomy a surgical incision (cut) of the cornea.
Keratitis inflammation of the cornea.
Kerato prefix indicating relationship to the cornea.
Keratoconus a disorder characterized by an irregular corneal surface (cone-shaped) resulting in blurred and distorted images.
Keratomileusis carving of the cornea to reshape it.
Laser the acronym for light amplification by stimulated emission of radiation. A laser is an instrument that produces a powerful beam of light that can vaporize tissue.
LASIK 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 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 a surgical device that is affixed to the eye by use of a vacuum ring. When secured, a very sharp blade cuts a layer of the cornea at a predetermined depth.
Monovision the purposeful adjustment of one eye for near vision and the other eye fordistance vision.
Myopia the inability to see distant objects as clearly as near objects.
Nearsightedness the common term for myopia.
Ophthalmologist a medical doctor specializing in the diagnosis and medical or surgical treatment of visual disorders and eye disease.
Optician an expert in the art and science of making and fitting glasses and may also dispense contact lenses.
Optometrist a primary eye care provider who diagnoses, manages, and treats disorders of the visual system and eye diseases.
Overcorrection a complication of refractive surgery where the achieved amount of correction is more than desired.
PRK 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 the inability to maintain a clear image (focus) as objects are moved closer. Presbyopia is due to reduced elasticity of the lens with increasing age.
Pupil a hole in the center of the iris that changes size in response to changes in lighting. It gets larger in dim lighting conditions and gets smaller in brighter lighting conditions.
Radial Keratotomy commonly referred to as RK; a surgical procedure designed to correct myopia (nearsightedness) by flattening the cornea using radial cuts.
Refraction a test to determine the refractive power of the eye; also, the bending of light as it passes from one medium into another.
Refractive Errors imperfections in the focusing power of the eye, for example, hyperopia, myopia, and astigmatism.
Refractive Power the ability of an object, such as the eye, to bend light as light passes through it.
Retina a layer of fine sensory tissue that lines the inside wall of the eye. The retina acts like the film in a camera to capture images, transforms the images into electrical signals, and sends the signals to the brain.
Radial keratotomy (RK) is a refractive surgical procedure to correct myopia. The procedure consists of numerous radial incisions which extend from the pupil to the periphery of the cornea in a pattern like the spokes of a tire. It was discovered by accident by Dr. Svyatoslav Fyodorov who removed glass from the eye of one of his patients who had been in a fight. The patient's eyesight improved after the glass was removed. In RK, incisions are made with a precision calibrated diamond knife. The incisions must be quite deep to cause central corneal flattening, and the procedure is not as precise as lasik and PRK. Few surgeons now perform RK because it is less predictable. Arcuate keratotomy is still popular to correct astigmatism. It is also done with a diamond knife but astigmatism cuts are done parallel to the edge of the cornea.
Sclera the tough, white, outer layer (coat) of the eyeball that, along with the cornea, protects the eyeball.
Snellen Visual Acuity Chart one of many charts used to measure vision.
Stroma the middle, thickest layer of tissue in the cornea.
Undercorrection a complication of refractive surgery where the achieved amount of correction is less than desired.
Visual Acuity the clearness of vision; the ability to distinguish details and shapes.
Vitreous Humor the transparent, colorless mass of gel that lies behind the lens and in front of the retina and fills the center of the eyeball.
Wavefront a measure of the total refractive errors of the eye, including nearsightedness, farsightedness, astigmatism, and other refractive errors that cannot be corrected with glasses or contacts.