aberration: An irregularity or departure from the norm. In this context, an imperfection in the eye affecting vision.

ablate: To remove; specifically, the removal of corneal tissue to reshape the cornea to correct vision problems using a laser.

ablation: Removal of corneal tissue to reshape the cornea to correct vision problems using a laser.

accommodate: Way by which the eye’s lens alters its focal point to bring near and far objects into focus.

AK: An acronym for astigmatic keratotomy, a refractive surgical procedure using a blade rather than a laser for the correction of astigmatism.

astigmatism: A vision problem that results in blurred distance and/or near vision. Light rays entering the eye are bent unequally, which prevents the formation of a sharp point of focus on the retina. This creates a blurring of parts of objects you see.

bacterial conjunctivitis: An eye infection commonly known as pink eye; caused by bacteria.

BCVA: An acronym for Best Corrected Visual Acuity, a measure of the best vision you can attain from glasses or contact lenses.

blepharitis: Inflammation of the edge of the eyelid.

broad-beam: A laser with a relatively large (6-8mm) diameter beam that can be manipulated to reshape the cornea in a refractive surgery procedure.

broad-beam laser: A laser with a relatively large diameter beam (6mm - 8mm) that can be manipulated to reshape the cornea in refractive surgery procedures.

cataract: Clouding of the lens inside the eye that can lead to a loss of vision.

CK: An acronym for conductive keratoplasty, a refractive surgical procedure which uses radio frequency (RF) energy to heat and shrink the corneal tissue. This “steepens” the cornea to create the desired refractive effect.

closed-loop: A constant connection between the eye tracking device and the laser system to influence the placement of the laser beam.

collagen: The principal protein of the skin, tendons, cartilage, bone and connective tissue.

coma: A higher order aberration which makes items appear to have a comet-shaped ”tail”, creating blurring in your vision.

conductive keratoplasty: Also known as CK, a refractive surgical procedure which uses radio frequency (RF) energy to heat and shrink the corneal tissue. This 'steepens' the cornea to create the desired refractive effect.

cornea: The clear front surface of the eye. Refractive surgeries like PRK, LASIK, LASEK and RK reshape this surface to correct vision problems.

corneal flap: A thin slice of tissue on the surface of the cornea made with a microkeratome at the beginning of a LASIK procedure. This flap is folded back before the laser is applied to the inner layers of the cornea.

CUSTOMCORNEA®: The branded name for the first FDA-approved customized laser vision correction procedure that addresses both higher- and lower-order aberrations to create truly customized vision correction.

dilated: Widening of the pupils achieved by placing drops in the eyes. Your vision will normally be blurry for up to several hours after dilation.

dilating: When eyes are dilated, the pupils are wider than normal. This is accomplished by placing drops in your eyes. Your vision will normally be blurry for up to several hours after dilation.

diopters: A unit of measurement for myopia, hyperopia and astigmatism that usually falls within a scale of +14 to -14. A positive number indicates hyperopia and a negative number indicates myopia. Positive and negative numbers are also used to indicate astigmatism. Whether the number is positive or negative, the higher the number the greater the extent of the vision problem.

dry eye: Dryness of eye tissue usually due to deficient tear production that can cause burning, stinging and the feeling that something is in the eye. This occurs commonly in LASIK patients in the weeks following surgery.

enhancements: A follow-up procedure. LASIK is sometimes performed a second time to improve upon initial results, or if your vision changes after surgery. Speak with your doctor to understand this process more fully.

epithelium: The protective layer of cells covering the cornea.

excimer laser: A type of laser used in laser vision correction that removes tissue from the cornea.

farsightedness: A common term for hyperopia, a vision problem that most commonly results in blurred close vision. Moderate to severe hyperopia may also result in blurred distance vision. The cornea and lens focus light rays behind, rather than directly on, the retina.

FDA: An acronym for the Food and Drug Administration, a federal agency within the U.S. Department of Health and Human Services responsible for determining the validity and safety of any drug, cosmetic, or medical device.

Gaussian beam: A type of small-spot laser beam, its unique rounded shape leaves the corneal surface smooth.

glaucoma: A condition usually associated with high eye pressure. This condition results in damage to the nerve at the back of the eye and possible loss of vision.

halo: A circular flare or hazy ring that may appear around a headlight or other lighted object.

halos: A visual effect, in which a circular flare or hazy ring of light may appear around a headlight or other lighted object.

hazy cornea: Corneal haze is a cloudiness of the normally clear cornea. Most types of haze disappear with time or after treatment with eye drops. Severe corneal haze may lead to reduced visual clarity.

higher order aberrations: A collective term for a series of imperfections in the eye’s optical system that may result in vision problems experts believe to be responsible for low-light vision difficulties.

hyperopia: A vision problem, commonly called farsightedness, that results in blurred close vision although moderate to severe hyperopia may also result in blurred distance vision. The cornea and lens focus light rays behind, rather than directly onto, the retina.

intraocular pressure (IOP): The pressure inside the eye produced by the fluids contained within the eye.

keratoconus: A disease of the cornea that causes a cone-shaped protrusion of the center of the cornea.

LASEK: An acronym for Laser Assisted sub-Epithelial Keratectomy, a refractive surgical procedure similar to PRK, where the surface cells (epithelium) of the cornea are removed prior to laser treatment. Then the laser reshapes the cornea to improve vision. Once the laser ablation is completed, the surface cells are replaced over the reshaped area.

LASIK: An acronym for Laser In-Situ Keratomileusis. LASIK is a type of laser surgery in which the cornea is reshaped to improve vision. A device called a microkeratome is used to surgically create a thin, hinged flap of corneal tissue. The flap is folded back, the laser is directed to the corneal surface exposed beneath the flap and the flap is brought back into place.

lens: A structure inside the eye that helps to focus light on to the back of the eye.

lower order aberrations: A collective term for a series of common vision problems including myopia, hyperopia and astigmatism.

microkeratome: A surgical instrument used to cut a flap of corneal tissue as the first step in the LASIK procedure.

misaligned flap: A rare condition in which the flap created with the microkeratome is displaced following the procedure. When this occurs the flap is usually repositioned.

mixed astigmatism: A type of astigmatism that results in blurred distance and near vision. Light rays entering the eye are bent at different points, with one point focused in front of the retina and the other point focused behind the retina. Clear vision requires that all focus points be directly on the retina.

monovision: An approach to vision correction that intentionally corrects one eye for distance vision and the other for close vision. This can be done with glasses, contact lenses, or various surgical procedures.

myopia: Another term for nearsightedness. A condition of the eye that results in blurred distance vision. The cornea and lens focus light rays from distant objects in front of the retina. This incorrect focusing of light results in blurred images of objects at a distance.

nearsightedness: A common term for myopia. A condition of the eye that results in blurred distance vision. The cornea and lens focus light rays from distant objects in front of the retina. This incorrect focusing of light results in blurred images of objects at a distance.

ocular: Having to do with the eye.

open-loop: The opposite of closed-loop, referring to the absence of a constant connection between the eye tracking device and the laser system to influence the operation of the laser beam.
ophthalmic: Pertaining to the eye.

ophthalmologist: A medical doctor who specializes in the eye and is licensed to perform surgery on the eye. All LASIK surgeons are ophthalmologists.

ophthalmology: Pertaining to the eye, its function, and diseases.

optometrist: An eye care specialist who specializes in the examination, diagnosis, treatment, management and prevention of diseases and disorders of the eye and associated structures.

over-corrected: An uncommon outcome of laser vision correction where the amount of correction is more than desired.

photorefractive keratectomy: Commonly referred to as PRK, it is a common laser vision correction procedure. PRK uses an excimer laser to remove tissue from the surface of the cornea.

presbyopia: An eye condition commonly due to aging and a stiffening of the lens, which results in an eye that can no longer accommodate for near or "reading" vision. The individual is no longer able to read clearly and typically requires reading glasses.

PRK: An acronym for Photorefractive Keratectomy, a refractive surgery procedure that uses an excimer laser to remove tissue directly from the surface of the cornea.

punctal plugs: A device that may be inserted into your tear ducts to preserve tears and keep corneas moist.

radial keratotomy: Commonly referred to as RK, this refractive surgical procedure flattens the central cornea with a series of spoke-like incisions.

refractive errors: Vision problems caused by an imperfect optical system, most commonly myopia, hyperopia and astigmatism.

refractive surgeon: An ophthalmologist who specializes in performing refractive procedures such as LASIK.

refractive surgery: Any surgical procedure performed to change the eye`s refractive error.

retina: The light sensitive nerve layer in the back of the eye that receives visual stimuli that are transmitted to the brain.

RK: An acronym for radial keratotomy, a refractive surgery procedure where radial cuts are made in the outer portions of the cornea, like spokes of a wheel, to flatten the central cornea.

saccadic: Involuntary eye movements. These rapid eye movements occur all the time, including during laser refractive surgery and may affect accurate placement of the laser beam.

saccadic movements: Involuntary eye movements. These rapid eye movements occur all the time, including during laser refractive surgery and may affect accurate placement of the laser beam.

small-spot laser beam: At less than 1 mm in width, this type of beam allows a LASIK specialist to perform corneal shaping in fine, gradual, precise increments, creating a smooth corneal surface.

spherical aberration: A visual disorder reflecting a change in curvature between the center and edge of the pupil. This creates multiple focal points and can cause halos in your vision.


starbursts: Flares of light seen around a lighted object that may appear like a star. This symptom is similar to halos and may occur after surgery.

sterile interface inflammation: An inflammatory reaction underneath the corneal flap after LASIK surgery that is not due to bacteria. In rare cases, this condition may result in vision loss.

tracking device: A component of some (but not all) laser vision correction systems designed to ensure accurate placement of laser treatment to the eye during the procedure.

under-corrected: An uncommon outcome of laser vision correction where the amount of correction is less than desired. Some surgeons may intentionally undercorrect a particular patient based on his or her individual situation and preference.

uveitis/iritis: Inflammation of the iris and other internal structures of the eye.

vaporization: The process by which the laser breaks the bonds of chemicals between individual molecules with little or no damage to surrounding cells. This process is also called photoablation.

visual acuity: Another phrase for visual clarity, a measure of the eye's ability to distinguish the shape of objects. Visual acuity is measured with a traditional eye chart, with the goal traditionally being 20/20.

wavefront device: A sophisticated measurement device, which passes a narrow ray of eye-safe light through the optical system and measures the optical distortions as the light exits the eye. With the LADARVision® system, the resulting wavefront maps are used to provide fully customized vision correction, to address both lower- and higher-order aberrations, through the CUSTOMCORNEA® procedure.

wavefront mapping: A sophisticated way to represent visual disorders, these maps are created by passing a narrow ray of eye-safe light through the optical system and measuring the optical distortions as the light exits the eye. With the LADARVision® system, the resulting wavefront maps are used to provide fully customized vision correction, to address both lower- and higher-order aberrations, through the CUSTOMCORNEA® procedure.