Glossary
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Glossary items starting with:
Glossary items starting with: A
Accommodation
(uh-kah-muh-DAY-shun). The ability of the eye and
specifically crystalline lens inside the eye to focus on near objects.
Add Power
This is the amount of power you would need in a bifocal, if any.
As you get older you lose the ability to focus at near. You may need
added power at the bottom rim of your lenses to help you see more
clearly at near with your existing eyeglass prescription. Whether
you are near sighted, far sighted, or have never worn eyeglasses at
all, you may need to wear a bifocal lens or reading glasses at some
point in your life.
After-cataract (secondary cataract)
After-cataracts are a type of cataracts that form after surgery
for other eye problems, such as glaucoma. After-cataracts also can
develop in people who have other health problems, such as diabetes.
They are sometimes linked to steroid use.
Amsler grid
(AM-slur). A small grid that tests for retinal disorders,
and is sometimes given to macular degeneration patients to take
home in order to monitor any changes in their condition.
Angle, anterior chamber angle
The area in the front of the eye where fluid from inside the eye drains out.
Aphakia
(ay-FAY-kee-uh). Once a patient has had a cataract removed,
the eye is considered "aphakic". If an intra-ocular lens is put in,
which is typical, the eye is considered "pseudo-phakic".
Aqueous
(AY-kwee-us). The liquid that fills the front chamber of the
eye to keep the eye round and the cornea nourished.
A-scan
A measurement of the length of the eye taken before cataract
surgery to properly determine the power of the lens implant.
Asthenopia
(as-then-OH-pee-uh). Any type of uncomfortable feeling in
the eye, or eyestrain.
Astigmatism
(uh-STIG-muh-tiz-um). An irregular shape to the cornea
causes this common refractive error that can usually be corrected
with glasses or contact lenses.
Axis
This is the degree the cylindrical correction sits at for optimal
vision. You will only have this measurement if you have cylindrical correction.
Glossary items starting with: B
Bifocals
Glasses that correct for blurred vision far away and up close.
Binocular vision
The two eyes working together to see one image without eyestrain.
Blepharitis
(blef-uh-RI-tus). A common bacterial infection of the eyelids and eyelashes,
requiring special hygiene measures and at times prescription medication.
Blind spot
An area in the field of vision where objects cannot be seen.
Everyone has a normal "physiologic" blind spot, but other blind spots
from strokes, glaucoma or other diseases are not normal.
B-scan
A 2 dimensional ultrasound view of the inside of the eye,
useful in looking beyond a cloudy cornea or hemorrhage in the eye
to determine the health of the retina.
Glossary items starting with: C
Cataract
A clouding of the normally clear human lens inside the eye,
causing vision to be blurred.
Cataract extraction
A surgical procedure done with ultrasound that removes
the cloudy lens to restore vision.
Central retinal artery
The main artery that supplies blood to the eye.
Central retinal vein
The main vein that circulates used blood from the eye back to the heart.
Central vision
Straight ahead vision, when you look directly at someone
or at a book to read.
Chalazion
(kuh-LAY-zee-un). A stye on the eyelid which is the result
of a blocked tear duct or infection.
Choroid
(KOR-oyd). A stye on the eyelid which is the result of a
blocked tear duct or infection.
Color blindness
The lack of ability to distinguish colors,
which can be inherited or acquired from a retinal disease.
Cone
A type of retinal nerve cell that is responsible
for central vision and color vision.
Conjunctiva
(kahn-junk-TI-vuh). The clear outer membrane covering the eye.
Conjunctivitis
(kun-junk-tih-VI-tis). Sometimes referred to as "pink eye",
an infection of the outer layer of the eye that can be caused by
a bacterial or viral infection.
Convergence
(con-VER-genc-es). The ability of the eyes to move in toward
each other, as when one is reading or looking at a near target.
Cornea
(KOR-nee-uh). The clear front covering of the eye, and the
first surface where light is focused onto the retina.
Crystalline lens
The clear human lens inside the eye, that along with
the cornea, focuses light onto the retina to create a clear image.
Cylindrical Correction
This part of the prescription is used to correct astigmatism.
Astigmatism is a condition that is caused when the shape of the
front of the eye is football like instead of round. Therefore,
the light passing through the eye is distorted and causes certain
degrees of blurriness. By adding this correction to the eyeglasses
you maximize clarity. This is the second set of numbers you will
find in a prescription. Usually, the "cylindrical" component is
"fine tuning".
Glossary items starting with: D
Diabetic retinopathy
(ret-in-AHP-uh-thee). Hemorrhages and abnormal blood vessels
seen in the retina of diabetics, especially those whose disease
is not controlled well.
Dilated pupil
A large pupil usually created by pharmacologic agents to
allow a better look inside the eye.
Diopter (D)
(di-AHP-tur). A unit of measurement that describes
the refractive power of a lens
Diplopia
Double vision, or seeing two or more objects
when there is only one.
Drusen
(DRU-zin). Small yellow or white deposits in the
retina frequently associated with macular degeneration.
Dry eye syndrome
A lack of tears produced by the eye's lacrimal gland,
thought to result from inflammation. This syndrome often leads
to discomfort, specifically stinging, burning and a scratchy feeling.
Glossary items starting with: E
Ectropion
(ek-TROH-pee-un). The lower eyelid can lose its elasticity,
causing it to turn outward, which sometimes can result in tear
drainage problems and excessive tearing.
Emmetropia
(em-uh-TROH-pee-uh). The refractive condition whereby
light is focused perfectly on the retina, and the person
sees 20/20 without any form of visual correction.
Entropion
(en-TROH-pee-un). The lower eyelid turns inward,
often resulting in eyelashes contacting the front of the
eye with resultant irritation.
Esotropia
(ee-soh-TROH-pee-uh). An inward turning of the eye,
commonly known as "crossed eyes."
Excimer laser
(EKS-ih-mur). An ultraviolet laser that removes human
tissue precisely and without heat, thereby shaping the eye
to reduce refractive errors such as reducing nearsightedness
(LASIK or PRK.
Excimer laser
(EKS-ih-mur). An ultraviolet laser that removes human
tissue precisely and without heat, thereby shaping the eye
to reduce refractive errors such as reducing nearsightedness
(LASIK or PRK.
Exotropia
(eks-oh-TROH-pee-uh). An outward turning of the eye,
commonly known as "wall-eye."
Extraocular muscles
(eks-truh-AHK-yu-lur). The muscles that control eye
movements, such as when one looks up, down or to the
left or right.
Eyelids
The thin membrane of skin that is designed to protect
the eye and keep it from drying out.
Glossary items starting with: F
Fluorescein Angiography
(FLOR-uh-seen an-jee-AH-gruh-fee). A dye is injected
into the vein and high speed photographs are taken to look
at the blood flow in the retina, meant to detect leakage of
abnormal blood vessels such as in diabetes or macular degeneration.
Fovea
(FOH-vee-uh). The very central part of the retina, used
for fine focus distance and near vision.
Fundus
The back of the eye, including the optic nerve and retina.
Glossary items starting with: G
Glaucoma
(glaw-KOH-muh). A progressive disease of the optic nerve,
often but not necessarily associated with high intraocular pressure,
leading to slow deterioration of side (peripheral) vision. If there is
a family history of glaucoma, other family members have up to a ten fold
chance of developing the disease and should be checked yearly.
Gonioscopy
(goh-nee-AHS-koh-pee). A technique to look at the angle,
the area of the eye where fluid drains out, which can be abnormal
in people with glaucoma.
Glossary items starting with: H
Hyperopia
(hi-pur-OH-pee-uh). Also known as far-sightedness,
where distant objects are seen more clearly that
print/objects up close.
Hyphema
(hi-FEE-muh). A hemorrhage inside the eye,
often resulting from blunt trauma.
Glossary items starting with: I
IOL (intraocular lens)
An artificial lens, typically made of silicone
or acrylic material, that is implanted in the eye at
the time of cataract surgery to replace the cloudy human
lens that is removed.
Iris
The colored part of the eye, which constricts or
dilates depending on lighting conditions.
Glossary items starting with: K
Keratoconus
(kehr-uh-toh-KOH-nus). A condition that causes the
cornea to warp or bulge, leading to a large degree of
astigmatism which requires treatment with either a rigid
contact lens or a corneal transplant procedure.
Keratometry
(kehr-uh-TAH-mih-tree). A measurement of the
curvature of the cornea.
Glossary items starting with: L
Lacrimal gland
The gland behind the upper eyelid that produces tears.
Laser
A powerful beam of light that is used in a variety
of forms of surgery to remove or vaporize tissue.
LASIK
(LAY-sik). Stands for "Laser Assisted In Situ
Keratomileusis" which involves cutting a flap on the
cornea, lifting it, and reshaping the cornea below
with an excimer laser to reduce nearsighted or farsightedness,
then replacing the flap.
Legal blindness
Typically defined in the U.S. as visual acuity (with glasses)
worse than 20/200 in the better seeing eye, or in combination with
significant peripheral vision loss.
Lens, crystalline lens
The lens inside the eye that, along with the cornea,
bends (refracts) light onto the retina in order to create
a sharp focus, allowing us to see clearly.
Low vision
The optometric specialty that involves helping those
who are legally blind to use their remaining vision using
strong magnifiers, telescopes, and daily living aids.
Low vision
The optometric specialty that involves helping those
who are legally blind to use their remaining vision using
strong magnifiers, telescopes, and daily living aids.
Glossary items starting with: M
Macula
The very sensitive central part of the retina
responsible for fine focus vision and the perception
of colors.
Myopia
(mi-OH-pee-uh). Also known as nearsightedness,
where objects up close are seen more clearly than
distant objects.
Glossary items starting with: N
Neovascularization
(nee-oh-VAS-kyu-lur-ih-ZAY-shun).
The formation of abnormal blood vessels,
as seen in poorly controlled diabetes,
which can lead to hemorrhages and retinal
detachment.
Nystagmus
(ni-STAG-mus). Rapid involuntary eye
movements that may be the result of poor
vision, or a neurological condition.
Glossary items starting with: O
Ophthalmologist
(ahf-thal-MAH-loh-jist). An eye doctor
who specializes in the diagnosis and
treatment of eye diseases and surgery
of the eye.
Ophthalmoscope
(ahf-THAL-muh-skohp). A lighted instrument
used to examine the back of the eye, specifically
the optic nerve and retina, to rule out conditions
such as retinal detachment, diabetes, glaucoma, etc.
Optic disc
The point where the optic nerve enters the
retina; not sensitive to light.
Optic nerve
The main nerve of the eye which carries
visual information from the retina to the
visual interpretation centers of the brain.
Optician
(ahp-TISH-un). A professional who specializes
in making and fitting eye glasses.
Optometrist
(ahp-TAHM-uh-trist). An eye doctor who
specializes in primary care of the eye,
including correction of the visual system
and the diagnosis and treatment of eye diseases.
Orthoptics
Eye exercises designed to strengthen eye
muscles and improve the way the eyes work
together and focus.
Glossary items starting with: P
Patching
Covering an amblyopic patient's
preferred eye, to improve vision in the other eye.
Perimetry
(puh-RIM-ih-tree). The measurement of the
peripheral or side vision, often done with
an automated computerized instrument.
Phacoemulsification
(fay-koh-ee-mul-sih-fih-KAY-shun).
An ultrasound technique used to break
up the cloudy lens (cataract) inside
the eye, allowing for a smaller incision.
Photophobia
(foh-toh-FOH-bee-uh).
Sensitivity to light or glare.
Pinguecula
(pin-GWEK-yu-luh).
A growth on the outside of the eye,
typically in the inner or outer corner,
thought to be related to long term
exposure to ultraviolet sunlight.
Presbyopia
(prez-bee-OH-pee-uh).
A condition that commonly develops after
age 40, resulting from aging changes to
the human lens and a lack of ability to
focus up close requiring reading glasses.
PRK
Stands for "Photo Refractive Keratectomy,"
a procedure to reduce or eliminate nearsightedness
by scraping the outer layer of the cornea and
using an excimer laser to shape the eye.
Progressive Addition Lens (PAL)
Invisible bifocals that focus light
at a variety of intermediate and near
distances.
Proliterative retinopathy
Pterygium
(tur-IH-jee-um). A vascular growth on the
outside of the eye, typically in the inner
or outer corner, thought to be related to
long term exposure to ultraviolet sunlight
that can grow onto the cornea and affect vision.
Ptosis
(TOH-sis). A droopy upper eyelid.
Pupil
The hole in the center of
the iris that light is directed
through onto the retina.
Glossary items starting with: R
Radial keratotomy (RK)
(keh-ruh-TAH-tuh-mee). A surgical procedure,
popular in the 1970's and 80's, that used eight
spoke-like incisions to induce flattening of the
cornea and correct nearsightedness. RK has been
replaced by LASIK and PRK.
Refraction
The measurement of the visual system to determine
the appropriate eyeglass or contact lens prescription.
Refractive error
The amount of nearsightedness,
farsightedness or astigmatism
that an individual has.
Retina
The inner lining of the eye,
consisting of sensitive nerve
cells that receive light images
and converts them to electrical
impulses that are sent the brain
by way of the optic nerve.
Retinal detachment
A separation of the retina from
the layers behind it, usually resulting
from injury or seen in patients who
are highly nearsighted. A retinal
detachment can be surgically repaired
but the amount of vision recovered
depends on the extent of the detachment
and how quickly it is diagnosed.
Retinoscope
(RET-in-oh-skohp). An instrument used
to determine the refractive error of
the eye by shining a light in the eye
and observing the reflected light images.
Rod
A type of retinal nerve cell responsible
for night vision and peripheral vision.
Glossary items starting with: S
Schlemm's canal
(shlemz). The drainage channel
where fluid exits the eye.
Sclera
(SKLEH-ruh).
The white protective
outer coating of the eye.
Slit lamp
Also called a biomicroscope,
used to magnify structures in
the front and back of the eye
to examine various structures
and diagnose abnormal conditions.
Snellen chart
A vision chart that is read
to determine one's visual acuity,
or clarity of vision.
Spherical Correction
This measures the amount of
correction that a person needs
to see clearly at near of distance.
This number can stand alone as a
prescription or be combined with
another set of numbers to complete
a prescription. This number is always
the first set of numbers in the
prescription.
Strabismus
(struh-BIZ-mus).
A misalignment of the eyes,
often leading to double vision.
Glossary items starting with: T
Tonometry
(tuh-NAH-mih-tree).
The measurement of the
pressure inside the eye,
often related to glaucoma.
Trabecular meshwork
(truh-BEK-yu-lur).
The drainage channel in the
front of the eye, and the area
that is lasered in glaucoma that
does not respond to medication.
Trifocal
(TRI-foh-kul).
A segmented lens for up close,
with one section for intermediate
(computer) range and another
for reading vision.
20/20
The smallest line of the eye
chart that someone with perfect
vision can see.
Glossary items starting with: U
Uvea, uveal tract
(YU-vee-uh). The middle layer
of the eye, sandwiched between
the retina and choroid, that
supplies the eye with nutrients
via the blood vessel system.
Glossary items starting with: V
Visual acuity
The level of clarity of vision.
Visual field
The total area that can be seen
both straight ahead and to the side.
Vitreous
(VlT-ree-us), vitreous humor.
The gel like substance that fills
the back chamber of the eye, helping
keep the eye round.
Vitreous detachment
A separation of the gel like
vitreous from the retina, in
some cases leading to a retinal
tear or detachment.