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The
vaporization of tissue with the excimer laser. |
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The
area of tissue that is removed during laser surgery |
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The
resolving power of the eye, as measured by the Snellen eye chart test.
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Automated
lamellar keratoplasty
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Medical term for an
eye with poor vision despite glasses. That eye's messages to the brain are weak,
and the other eye is preferred by the brain. If amblyopia is due to strabismus, the
condition may be corrected by wearing a patch over the stronger eye, by strengthening
the weaker one. If the condition is not corrected, the weak eye can become blind.
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A
difference in imaging size between the two eyes |
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A
difference in refractive power of the two eyes in which the variance
is at least one diopter.
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The
fluid-filled area between the cornea and the lens
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The
fluid in the anterior chamber |
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The
device is the first to be approved in the United States that can
give some, but not all, cataract patients the ability to see both
long and short distances. Traditional lens implants can restore
long-distance vision, but the vast majority of patients still require
reading glasses.
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Refers
to the cornea's natural optical shape. This shape determines the
number of light rays falling on the retina and the sharpness of
image under all types of lighting conditions. When asphericity is
altered, there can be optical aberrations such as glare or shadows.
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A
refractive error caused by an irregular shape of the cornea (much
like a football). Astigmatism is measured in terms of diopters,
cylinder meridian or axis. Uncorrected astigmatism may produce ghosting
or double images.
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A
procedure in which the surgeon first creates a flap in the uppermost
layer of the cornea using a device called a microkeratome. Then the
surgeon makes an optical cut after removing additional tissue with
a second pass of the microkeratome. |
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In
ophthalmology, a line that is the symmetrical center of a curved optical
surface. Measure of astigmatism. |
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Best
corrected visual acuity. |
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The
best possible vision a person can achieve with corrective lenses measured
in terms of Snellen lines on an eye chart. |
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Having
one segment for near vision and one segment for far vision. |
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The
non-regenerative layer of tissue between the epithelium and the
stroma (5-10 microns thick - .005 to .01 millimeters).
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A
medical instrument that produces a powerful beam of light that is
focused at close range to remove corneal tissue. A broad beam laser
uses a relatively large beam diameter (from 6.0 to 8.0 millimeters)
which can be manipulated to ablate the cornea. |
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Cataracts
occur when the natural lense of the eye becomes clouded. This leads to blurred, indistinct
vision, and in some cases can lead to blindness. |
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When
displayed, this mark indicates a medical device fulfills requirements
for sale in the 15-nation European Union. |
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A
manageable complication of LASIK related to ablation.
The incidence of center islands has been greatly reduced as more ophthalmic
research has been devoted to its contributing factors |
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The
cornea's critical area for clear vision. |
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CK is a procedure that uses controlled release of radio frequency energy to
reshape the cornea. The procedure is minimally invasive and takes less than
three minutes to perform. It requires a topical anaesthesia, and can be performed
in-office. Conductive Keratoplasty is currently best prescribed for farsighted patients
over the age of forty.
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A
method of testing overall vision quality across a range of spatial
"frequencies." Medical literature says this is a more comprehensive
test than the standard Snellen
test that measures only one spatial frequency: acuity. |
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The
outer part of the eye that provides 70% of the eye's refractive power.
The cornea is approximately 500 microns thick (.5 millimeter) and
consists of 5 layers - epithelium, Bowman's membrane, stroma, Descemet's
membrane and endothelium |
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The
area outside the central optical zone. Also, where KeraVision's Intacs
are placed |
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The
computerized videokeratography system (EYESYS) projects a 16-ring
(8 light and 8 dark rings) onto the surface of the cornea. A CCD camera
in the housing of the corneascope captures the image of the projected
rings. A total of 5,760 points at 1 degree intervals of the cornea
are measured. A number of sophisticated computer programs interpret
the data and create a series of color graphics displays. If needed,
a hard copy can be obtained from a color printer, Polaroid camera,
or a 35mm slide. |
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The
Council for Refractive Surgery Quality Assurance |
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In
ophthalmology, a line that is the symmetrical center of a curved optical
surface. Measure of astigmatism. |
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A
complication caused by movement of the pupil that can be corrected
with an enhancement procedure. |
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The
layer of the cornea between the stroma and endothelium. Five microns
thick (.005 millimeters), this membrane provides an adhesion layer
for the endothelium. |
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The
balance of hydration in the eye. |
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Altered sugar
metabolism results in poor circulation and abnormal metabolism of the retinal
cells. Vision can be damaged by cell loss and hemorrhage. Careful frequent eye
examinations are necessary to detect diabetic damage in early stages. Treatment
can limit the possible harm and increase a person's chances of good vision for a
lifetime. |
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A
measurement of refractive error. Hyperopia is measured in terms of
positive diopters. Myopia is measured in terms of negative diopters.
The most common refractive errors ranged between +6 to -6 diopters |
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A
Syndrome characterized by corneal dryness due to deficient tear production. |
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A
progressive corneal thinning and bulging. |
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People
who have no refractive error. |
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The
ophthalmic term for a perfect refractive state. A normal eye in which
light rays focus correctly on the retina. - no nearsightedness, farsightedness
or astigmatism |
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The
innermost layer of the cornea. The endothelium is one cell layer thick
(5-10 microns or .005-.01 millimeters) and provides hydration balance
to maintain the cornea's transparency. The endothelium serves three
main purposes it regulates the stroma's water content, provides a
barrier to ingress of several constituents of the aqueous humor, and
actively transports glucose. |
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A
secondary refractive procedure performed after the initial one in
an attempt to achieve better visual acuity. |
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The
watery eye; a disease in which the tears accumulate in the eye, and
trickle over the cheek. |
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A
complication of LASIK wherein epithelial cells grow underneath the
corneal flap. |
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The
outermost layer of cells of the cornea. Six cells thick (20 microns),
the epithelium is the eye's first defense against infection. |
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A
"cold" laser used in refractive surgery to remove corneal tissue.
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A doctor with the
F.A.C.S. abbreviation following his name is a
Fellow of the
American College of
Surgeons.
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A condition in which the eye becomes to short from front to back,
causing images to focus behind the retina instead of directly on it. Because of this error, close objects
become blurry and difficult to focus on. Farsightedness is measured in positive diopters. The farther
the number is away from zero, the more extreme the farsightedness.
Fellow of the
American College of
Surgeons.
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A
distortion of image due to irregular healing of the corneal surface.
|
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A
complication of refractive surgery in which the patient sees additional
luster around lights. Glare is a subjective experience that often
decreases with time. |
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Diseases of the eye in which the optic nerve is damaged, usually slowly but
progressively, by a level of pressure in the eye which interferes with the
normal blood flow to the nerve. Most cases are called chronic simple glaucoma.
|
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The
eyeball. |
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A
complication of refractive surgery in which the patient sees additional
rings around lights at night. Halos are subjective experiences that
often decrease with time. |
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A
relatively rare complication of LASIK caused by the deposition of
ground substance in the cornea. An ophthalmologist can measure the
haze response of a patient's eye under a slit lamp, but patients'
experiences of haze vary. Outcomes for the patient include decreased
night vision, halos or loss of best corrected visual acuity. Caused
by the eye's reaction to the laser, haze often decreases with time
and is more common with PRK. |
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People
who are farsighted. |
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The
ophthalmic term for farsightedness. In the hyperopic eye, images are
focused in back of the retina. The hyperopic eye is often described
as being too flat or too short. |
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Intacs
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The
first FDA-approved non-laser option for the surgical correction of
mild myopia. When surgically placed in the periphery of the cornea,
KeraVision's Intacs are designed to flatten the central cornea so
that light enters the eye at the proper angle for clear vision. Unlike
other treatments, Intacs are removable. The procedure is designed
to be performed without cutting or removing tissue from the cornea's
central optical zone, the critical area for clear vision. Also known
as the ICRS®, or Intrastromal Corneal Ring Segments. |
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The
pressure the fluid contained within the eye exerts on the globe. |
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The
tissue behind the cornea that gives color to the eye (blue, brown,
hazel, etc.). It controls the amount of light that can enter the eye
by varying the size of the pupil. |
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A
refractive error caused by an irregular shape of the cornea in which
the curve on one side of the meridian or axis is not symmetrical with
the curve on the other side. |
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The
Latin word for eye. |
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The
portion of the LASIK procedure in which the surgeon raises a thin
layer of the cornea, creating a corneal flap, to expose the layer of the cornea called the
stroma. |
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A
rare inherited condition of the cornea in which the cornea is steepened
to the point of being cone-shaped. |
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The
carving of the cornea formerly done with a lathe and blade, now done
with an excimer laser |
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The
replacement (transplantation) of the cornea. Keratoplasty can be lamellar
(replacement of superficial layers) or penetrating (replacement of
the full thickness of the cornea). |
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A
surgical incision (cut) of the cornea. |
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The
replacement of superficial layers of the cornea with the layers of
another donor cornea. |
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An
acronym for light amplification by stimulated emission of radiation.
A medical instrument that produces a powerful beam of light and can
produce intense heat or cool vaporization when focused at close range.
Lasers are often used in surgery to remove tissue. |
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The
acronym for laser assisted in situ keratomileusis. The name refers
the use of a laser to reshape the cornea without invading the adjacent
cell layers |
|
The
acronym for laser epithelial keratomileusis. The LASEK procedure is a variation on PRK.
LASEK uses a finer blade than LASIK, making it ideal for patients with thinner corneas or an
overall flatter eye. After the flap is cut, an excimer laser is used to sculpt the cornea
in much that same way as LASIK and PRK. |
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A
focusing part of the eye. It is curved on both sides and acts as a
camera lens to focus light on the retina. |
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Scars
that are dense and white. |
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Oily
secretions from the eyelid glands that supply the outer portion of
tear film, prevent rapid tear evaporation and tear overflow. |
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The
instrument a surgeon uses to create the corneal flap in the uppermost
layer of the cornea during the LASIK procedure. |
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One
thousandth of a millimeter. |
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1)
The purposeful adjustment of one eye for near vision and the other
for distance vision accomplished with either corrective lenses or
surgery. 2) A technique to limit the effects of presbyopia by correcting
one eye for near vision and the other for far vision. |
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People
who are nearsighted. |
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The
medical term for nearsightedness. Eye is too steep, too long, image
is focused in front of the retina. |
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A condition in which the eye becomes to long from front to back,
causing images to focus in front of the retina instead of directly on it. Because of this error, objects at a
distance become blurry and difficult to focus on. Nearsightedness is measured in negative diopters. The farther
the number is away from zero, the more extreme the nearsightedness. |
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Scars
that are translucent. |
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A
surgeon's adjustment to the laser's computer calculation to further
refine his or her own results. |
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The
permissible use of an approved drug or instrument in a way that has
not been specifically sanctioned. |
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The
millions of optical nerve fibers connecting to the eye and terminating
in the brain where images are created and processed. |
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The
result achieved when the change to refractive error exceeds the attempted
correction. |
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The
process of measuring corneal thickness, usually using an ultrasonic
probe |
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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. |
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Pink eye, the common
name for conjunctivitis, is an inflammation or infection of the conjunctiva, the
outer, normally clear covering of the sclera, the white part of the eye. The eye
appears pink in conjunctivitis because the blood vessels are dilated. Pink eye is
often accompanied by a discharge, but vision is usually normal, and discomfort is
mild.
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Characterized
by no refractive error. |
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Polymethylmethacrylate.
A clear polymer used in KeraVision's Intacs. Used since 1952 in intraocular
lenses related to cataract surgery |
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A
regulatory body's allowance of practitioners to make decisions to
best serve their patients |
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PRELEX
SM is a term used to describe presbyopic
lens exchange with a multifocal intraocular lens. Unlike procedures that
focus on changing the shape of the cornea, PRELEXSM
works on the lens inside the eye. Consequently, your vision after the procedure will
be stable and unlikely to change over time. |
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The
natural deterioration of near vision caused by loss of flexibility
in the eye's lens as one ages. A variant of farsightedness, or hyperopia.
Results from the loss of elasticity in the eye's lens, often as part
of the aging process. |
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Droopy
eyelid.
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|
The
black, circular opening in the center of the iris (the colored portion
of the eye). The pupil controls the amount of light that enters the
eye. |
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A
surgical procedure designed to correct myopia (nearsightedness) by
flattening the cornea with incisions. The procedure is called a radial
keratotomy because the incisions resemble the spokes in a wheel. |
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The
eye's focusing power. The bending of light wave as they pass from
one medium to another |
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Any
surgical procedure that attempts to decrease the patient's refractive
error. Typically the surgeon alters the shape of the cornea in order
to change the angle at which an image is projected onto the retina |
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A
refractive error caused by an irregular shape of the cornea (usually
a football shape) in which the curvature is symmetrical across one
or more meridians or axes |
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Light
processing membrane; converts light into electrical impulses that
are transmitted to the optic nerve |
|
The retina pulls away from deeper layers of the eye and cannot function. If unrepaired
the retina will degenerate. Surgery is usually necessary. |
|
Table-top
microscope for examining the eye. |
|
An
eye chart used to test a patient's vision |
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A
line of same-sized letters on an eye chart that is used to test a
patient's vision. |
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The Snellen test
measures quantity of vision; contrast sensitivity measures the overall
quality of vision. Contrast sensitivity is related to everyday visual
performance such as driving a car. Situations like reading a road
sign or seeing in fog and rain are taken into account in the contrast
sensitivity test. These low-contrast "real world" situations do not
necessarily correlate to the high-contrast test conditions of a Snellen
eye chart. |
|
A
medical instrument that produces a powerful beam of light that is
focused at close range to remove corneal tissue. Spot scanning lasers
use radar technology to track the eye's movement. |
|
Strabismus (Crossed Eyes)
|
The eye muscles are out
of balance. Double vision, poor depth perception, poor vision in one eye, or poor
cosmetic appearance can result. |
|
The thickest
part of the cornea (450-600 microns - approximately .5 millimeters).
It is between Bowman's membrane and Decemet's membrane. This middle tissue
layer of the eye makes up about 90 percent of the cornea. The
stroma is composed of densely packed layers similar to pages of a
book. |
|
Styes
|
Blocked inflamed oil gland of the eyelid. This may require surgical drainage,
but first hot compressing may help. |
|
|
SRP uses a tiny patented
device (the "Scleral Expansion Band" or "SEB") to reverse presbyopia in the human eye.
SRP is designed to restore the human eye in persons in their mid-40's or older to
the physiological condition of a much younger eye. The company believes that SRP will
benefit the patient for a considerable number of years.
|
|
When the
refractive error in both eyes are close to the same value. |
|
A
very thin film of water and other chemicals riding on top of the epithelium
that lubricates the front of the eye. |
|
The
Council for Refractive Surgery Quality Assurance (CRSQA,
pronounced SURS-kah) is an independent, nonprofit patient/consumer
public benefit health organization with two purposes; (1) certify
refractive surgeons who meet CRSQA's standards of quality of care;
(2) educate the public about refractive surgery and the availability
of CRSQA Certified Refractive Surgeons"! through seminars, publications,
public speaking, and the Internet. |
|
Anaesthetic
eye drops.
|
|
A
lens design that has three focal areas: a lens for close work or reading,
a lens for mid-distance viewing or arm's length, and a lens for faraway
viewing or driving. |
|
Uncorrected
visual acuity |
|
A
person's vision without corrective lenses measured in terms of Snellen
lines on an eye chart. |
|
The
result achieved when desired change in refractive error is not fully
achieved. |
|
The
gel-like fluid in the main cavity of the eye behind lens and pupil.
|
