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glossary
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
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.
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.
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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.
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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.
cornea: The clear front surface of the eye. Refractive surgeries
like PRK, LASIK 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.
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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 due to deficient tear production
that can cause burning, stinging and the feeling that something is in the
eye. This occurs commonly in post-LASIK patients in the weeks following
surgery.
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enhancements: A follow-up procedure or retreatment. LASIK is
sometimes performed a second time if the results were not satisfactory
after the first procedure. 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.
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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.
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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.
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halo: A circular flare or hazy ring that may appear around a
headlight or other lighted object. This symptom may occur after surgery.
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 that most commonly 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 on, the retina.
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Intraocular Lenses (IOLs): Artificial lenses made of plastic,
silicone, or acrylic which are implanted in the eye to improve its focus
and correct vision problems.
Intraocular Pressure (IOP): The pressure inside the eye produced by
the fluids contained within the eye.
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Keratoconus: A disease of the cornea that causes a cone-shaped
protrusion of the center of the cornea.
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LASEK: An acronym for Laser Assisted sub-Epithelial Keratectomy, a
refractive surgical procedure which uses an instrument called a trephine
to remove the surface cells (epithelium) of the cornea prior to laser
treatment. Once the laser ablation is completed, the surface cells are
replaced over the reshaped area.
laser radar tracker: This type of tracker is capable of tracking
involuntary eye movements during surgery to ensure accurate laser beam
placement.
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.
LTK: An acronym for Laser Thermal Keratoplasty, a refractive
surgical technique in which collagen, a major constituent of the cornea,
is heated with laser beams to correct hyperopia. The LTK procedure is
performed by applying the laser directly on the eye in specific spots
around the cornea.
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microkeratome: A surgical instrument used to cut a flap of corneal
tissue as the first step in the LASIK procedure.
misaligned flap: A 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 LASIK that intentionally corrects one
eye for distance vision and the other for close vision.
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.
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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.
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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: The art and science of eye medicine.
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: A complication of laser vision correction where the
amount of correction is more than desired.
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Photorefractive Keratectomy: Commonly referred to as PRK, it is a
common laser vision correction procedure. PRK uses an excimer laser to
remove tissue directly from the surface of the cornea.
presbyopia: A condition commonly due to aging, is due to a
stiffening of the lenses, 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 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.
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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 surgery: Any surgical procedure performed to change the
eye`s refractive error.
registration: Refers to the synergistic operation of the
LADARVision® 4000 Excimer Laser System and the LADARWave™ Wavefront
Device. These devices computer-match the wavefront image of your eye and
transform it into a customized ablation profile to guide treatment by the
laser.
retina: The light sensitive nerve layer in the back of the eye that
receives visual stimuli that are transmitted to the brain.
retreatments: A follow-up procedure or enhancement. LASIK is
sometimes performed a second time if the results were not satisfactory
after the first procedure. Speak with your doctor to understand this
process more fully.
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.
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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 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. This
condition may result in vision loss.
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tracking device: A component of some (but not all) laser vision
correction systems designed to monitor the movement of the eye during the
procedure.
trephine: A device that creates a circular opening in corneal
tissue.
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under-corrected: A complication 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.
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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.
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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.
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