20/20 Vision
This fraction is customarily used to indicate normal vision.
When the bottom number is larger than 20, it indicates impaired vision.
For example, when Molly has 20/400 vision.
She sees an object at 20 feet that another person with "normal vision" (20/20) can see at 400 feet.
Astigmatism
When a cornea is perfectly spherical, no astigmatism exists.
Yet, often the cornea is not quite spherical,
but shaped more like a football rather than a basketball.
Due to this shape, light that passes through the cornea
focuses in more than one point, causing images to distort.
Confrontation Visual Fields
A test of peripheral vision performed to identify defects
in the visual system that may indicate disease.
Cornea
This is the clear tissue that covers the iris.
The cornea is made up of five layers, and aids in focusing.
Refractive procedures involve changing the shape of the cornea.
Corneal Topography
Computerized map of the corneal surface identifying surface irregularities such as astigmatism.
It also provides a quantitative measure on corneal curvature.
Cover Test for Latent Strabismus
This measures how well the eyes work together.
Cycloplegic Refraction
The true eyeglass prescription when focusing ability
has been inactivated through the use of eye drops.
Dilated Fundus Examination
An examination of retinal tissue health in the back of the eyes.
Dilation
Dilating the eyes enables the doctor to do a dilated fundus examination to determine
the health of the retinal tissue at the back of the eyes.
Excimer Laser
This "cool" laser utilizes ultraviolet light to
modify the front area of the eye by breaking intra-molecular
bonds in collagen molecules.
The excimer laser is so precise that it can etch
a person's name into a single strand of human hair.
Hyperopia
When the cornea is too flat, rays of
light tend to focus behind the retina.
This causes a blurred view of nearby objects,
while distant objects can still be seen clearly.
Hyperopia is commonly known as farsightedness.
Iris and Pupil
The iris is the part of the eye that has the color—usually brown, blue, or green.
It works similarly to the iris of a camera by adjusting
the size of the opening or aperture (the pupil).
This regulates the amount of light admitted into the eye.
Lens
This transparent composition focuses light rays which pass through it.
The lens sits behind the iris and provides approximately
35% of the focusing capacity.
(The rest of the focusing ability is provided by the cornea.)
Manifest Refraction
The eyeglass prescription that best corrects the vision.
Monovision
With monovision, the laser will undercorrect one eye for near vision and fully correct
the other eye for distance vision.
You will not have to close one eye to read or close one eye to see in the distance.
Both eyes remain open and the brain chooses which eye
to look through depending on whether the object of your
attention is near or far.
Myopia
When the cornea is too steep or too long,
rays of light tend to focus in front of the retina.
This causes a blurred view of distant objects,
while nearby objects can still be seen clearly.
Myopia is more commonly known as nearsightedness.
Pachymetry
Measures corneal thickness.
Since Lasik corrects vision by removing a thin layer of corneal tissue,
this measurement verifies the safety of the procedure for each patient.
Presbyopia
During the natural aging process, you may begin to experience a change in your reading vision.
This change, which usually occurs around age 40,
is due to a loss of elasticity in the part of the eye known as the lens and its related muscle system.
With this loss of elasticity, "you lose the ability to focus up close. And you find yourself needing some type of assistance for reading.
This condition is known as presbyopia.
Pupil Size in Dim Illumination
One of the determinants for the level of glare symptoms after Lasik.
If the pupil dilates in the dark to a size that is larger than the
treatment zone of the laser, there is a risk of glare in the dark.
Pupil Testing for Size
Determines the risk level for glare after LASIK.
If the pupil dilates in the dark to a size that is larger than the treatment zone
of the laser, there is a risk of glare in the dark.
Refractive Error
This is what happens when there is a problem with the shape of the cornea or the lens.
The abnormal refraction or bending of the light beams
as they pass through these two transparent parts of the eye,
results in an inability to focus the image precisely onto the retina.
LASIK is designed to correct specific refractive errors.
Retina
This layer of light-sensitive tissue lines the back of the eye.
It enables the brain to receive visual messages via the optic nerve.
Slit Lamp Examination
A microscopic evaluation of the front and back health of the eyes.
Strabismus
This condition often called "lazy eye" occurs mainly in early childhood and results
from poor muscle coordination between the eyes.
It also occurs in adults. When looking at the lazy eye,
it appears as though the lazy eye is not looking directly at you when, in fact, it is.
This may or may not mean a patient is not a candidate for LASIK.
Less than 5% of the population have strabismus.
Tonometry
This test measures the pressure within the eyes, and is used as a glaucoma screening test.
Visual Acuity
This is a measurement of the eye’s
ability to detect and resolve an object at a given distance.
