Term |
Definition |
Aberrations |
Imperfections, irregularities,
and/or distortions of the optical quality of the eye that
cause unclear vision |
Ablation |
Removal of tissue as is
done with the excimer laser during refractive surgery |
Ablation
Zone |
The area of tissue removed during refractive
surgery; needs to approximate the pupil size to avoid post-op
glare and halos |
| Accommodation |
The ability of the lens inside the eye to change focus from
distance to near range; begins to decrease in our 40s requiring
the use of reading glasses |
Astigmatism |
A refractive error caused
by an uneven power of the cornea; light entering the eye comes
to two points of focus rather than one; has an amount and
an orientation |
Axis
|
The orientation of an
astigmatic correction |
Best
Corrected Visual Acuity (BCVA) |
Noted as BCVA; The best possible
vision that an eye can achieve with the use of glasses or
contact lenses |
Broad
Beam Laser |
An excimer laser with
a large treatment beam diameter (6mm to 8mm) that can be used
to ablate the cornea |
Cataract
|
An age-normal loss of clarity of the natural lens inside of the human eye. Typicaly develops later in life and can reduce vision due to the inability of light to enter the eye. |
| Contrast Sensitivity |
The ability to detect subtle differences
between details that are not black on white such as shades
of gray; important in determining the quality of vision after
refractive surgery |
Cornea |
The clear dome of tissue at the front
of the eye that is the first element of the focusing system;
provides two-thirds of the eye’s focusing power |
Corneal
Topography |
A computer-derived, color-coded
representation of the architecture and shape of the cornea;
a map of your eye |
Customized Ablation |
The use of wavefront sensing technology
and a flying spot excimer laser to treat all of the lower
and higher order aberrations of the human eye |
Cylinder
|
The amount of lens power
necessary to compensate for astigmatism |
Diopter |
Unit of measurement for the
power of a lens or of refractive error |
Dry
Eye |
A condition of the eye in which adequate
tears are not being produced to keep the surface of the eye
moist and lubricated |
Emmetropia |
A condition in which there
is no measurable refractive error; a near perfect focus of
the eye |
Enhancement |
A repeat of a refractive surgical
procedure in an attempt to improve vision without glasses |
Epithelium |
Top surface layer of the cornea; 6 - 7
cells thick |
Excimer
Laser |
The ultraviolet laser
used to remove corneal tissue during refractive surgery |
Eye
Tracker |
The device used by the excimer laser’s
computer that allows it to adjust the treatment beam to compensate
for small movements of the eye |
Flying Spot
Laser |
The latest generation
excimer laser that uses a small (1mm - 2mm) diameter treatment
beam to very precisely re-sculpt the cornea |
Glare |
A complication of refractive surgery that
causes points of light of look brighter and less distinct |
Halos |
A complication of refractive surgery
that causes a point of light to appear to have rings of light
around it |
Haze |
A complication of PRK in which the epithelium
of the cornea does not heal with perfect clarity |
Higher
Order Aberrations |
Subtle imperfection of the optics
of the eye above and beyond nearsightedness, farsightedness
and astigmatism; not corrected with glasses or contact lenses |
Hyperopia
or Farsightedness |
A refractive error in which
the optics of the eye are not strong enough for the front
to back length of the eye and the light is focused behind
the retina; objects at a distance focus better than objects
up close |
| Inflammation |
Human tissue’s natural reaction
to trauma; often accompanied by discomfort, redness and swelling
|
INTACS |
Intrastromal corneal rings;
a non-laser refractive surgical option for low degrees of
nearsightedness |
| Implant, Aphakic |
A small artificial lens placed into
the eye to restore the eye's focus after cataract surgery
to remove a cloudy natural lens |
| Implant, Phakic |
A small artificial lens placed into the
eye along with the eye's natural lens to reduce significant
amounts of refractive error such as myopia |
Iris |
The colored portion of
the eye behind the cornea |
Keratomileusis |
Re-sculpting of the shape of the cornea
to change its focusing power; refractive surgery |
| LASEK |
Laser Epithelial Keratomileusis; a
variation of refractive surgery in which the corneal epithelium
is slid back prior to laser treatment and then repositioned
after the treatment |
LASIK
|
Laser In-Situ Keratomileusis;
the refractive surgical procedure where a flap of tissue is
created in the cornea, lifted allowing the excimer laser to
re-shape the cornea to correct refractive errors and then
repositioned where it naturally re-adheres |
Lens |
The part of the eye behind
the iris that adjusts focus for different distances by changing
shape |
Macula |
The central portion of the
retina responsible for high detail, color vision |
Microkeratome |
A very precise surgical
device used to create the corneal flap during the LASIK procedure
|
Micron |
The precise unit of measurement used in
refractive surgery; equal to 1/1000th of a millimeter or one
millionth of an inch |
Monovision |
The intentional adjustment
of vision in one eye for near clarity and the other for distance
clarity during refractive surgery or when prescribing contact
lenses |
Myopia
or Nearsightedness |
A refractive error in which
the optics of the eye are too strong for the front to back
length of the eye; objects up close focus better than those
at a distance |
| Nomogram |
The adjustments made to diagnostic data in the process of creating a treatment profile for use with laser vision correction |
Optic Nerve |
The bundle of 1 million
nerves that transmits information from the retina (back of
the eye) to the visual center of the brain |
| Overcorrection |
A situation in which the change in refractive error following
refractive surgery is greater than the intended treatment |
| Pachymetry |
A precise technique for measuring the exact thickness of
the cornea |
| Plano |
The term for zero refractive power. No lens is necessary
to improve the focus of light into the eye. |
| Presbyopia |
The normal aging process of the human lens which causes
a loss in flexibility resulting in the inability to focus
on near range objects |
| PRK |
Photorefractive Keratectomy; a type of refractive
surgery in which the epithelium of the cornea is removed prior
to laser treatment and then allowed to naturally regrow |
| Pupil |
The black opening in the center of the iris that allows
light into the eye; its size increases under dim lighting |
| RK |
Radial Keratotomy; an early version of refractive surgery
for myopia that involved making spoke-like cuts in the peripheral
cornea |
| Refraction |
The test used to determine the amount of nearsightedness,
farsightedness and/or astigmatism |
| Refractive
Error |
Any condition in which light entering the eye
is not focused precisely on the retina |
| Regression |
A loss of refractive surgical effect in the time period
following treatment |
| Retina |
The light sensitive, back part of the eye containing
the rods and cones that turns light waves into brain waves
allowing us to see |
| Rochester Nomogram |
A specialized method of analyzing the wavefront sensing data for a patient's eye during the creation of a laser vision correction treatment plan. Created by, and unique to, StrongVision
|
| Snellen Chart |
The eye chart commonly used to measure visual acuity, where
good vision is 20/20 |
| Sphere |
The amount of lens power needed to compensate
for nearsightedness or farsightedness |
| Stroma |
The central substance of the cornea that is treated with
the excimer laser during refractive surgery |
| Tear Film |
The thin layer of lubricants and nutrients that covers the
front surface of the cornea |
| Uncorrected
Visual Acuity |
Noted as UCVA; The best possible vision that
an eye can achieve without the use of glasses or contact lenses |
| Undercorrection |
A situation in which the change in refractive
error following refractive surgery is less than necessary |
| Verisyse™ |
A tiny lens implant placed into the
eye, without removing the eye's natural lens, to reduce the
impact of very high degrees of myopia |
Wavefront
Sensing |
A
computerized technology that analyzes all the eye’s
higher order aberrations as well as nearsightedness, farsightedness
and astigmatism |
