Important Glaucoma Terms

acetazolamide (Diamox)

A medicine that lowers eye pressure in pill form, a carbonic anhydrase inhibitor.

acute angle closure crisis (attack)

A sudden increase in eye pressure caused by several defects in movement of aqueous fluid in the eye. Symptoms are pain, redness, blurred vision and abnormal shaped pupil. A true emergency for which immediate care should be given.


The degree to which patients correctly take their medicine.

aerobic exercise

Physical activity that raises the pulse rate substantially for a sustained period, which is known to lower eye pressure.

age-related macular degeneration (AMD)

A disease affecting the center part of the vision by altering the nerve tissue called the retina and the underlying retinal pigment epithelium.

alpha adrenergic agonist eye drops

These eye drops reduce intraocular pressure by decreasing the production of aqueous humor and increasing its drainage through the uveoscleral pathway. Examples are brimonidine (Alphagan), apraclonidine (Iopidine), and dipivefrin (Propine).


The junction of the iris and the cornea on the inside front part of the eye where aqueous fluid drains into the blood stream from the eye along an area shaped like a circle.

angle closure

A mechanism that can lead to primary glaucoma in which the iris closes off the angle by moving forward.

angle closure glaucoma

A type of glaucoma caused by a blockade of movement of aqueous humor out of the eye as the iris is pushed against the trabecular meshwork.

anterior chamber

The front chamber of the eye between the cornea and iris that is filled with a liquid called aqueous humor.

anterior segment optical coherence tomography (ASOCT)

An imaging method that shows the dynamic behavior of structures in the anterior chamber of the eye.


Drugs like mitomycin-C sometimes used to decrease scarring and increase success of trabeculectomy surgery for glaucoma.


The name for the mode of retinal ganglion cell death in glaucoma, a form of cell suicide in which a protective mechanism from fetal life is reactivated by the disease.

apraclonidine (Iopidine)

An alpha adrenergic agonist eye drop

aqueous humor

The fluid filling the front of the eye that is produced at the ciliary body and exits from the trabecular meshwork and the uveoscleral outflow pathway. The balance between how much is made and how much leaves determines the eye pressure.

argon laser trabeculoplasty (ALT or LTP)

An outpatient treatment that can lower eye pressure.


Describes a condition in which the patient does not know it is happening.

benzalkonium chloride

a chemical added to many eye drops to keep bacteria from growing in the solution, a preservative, which can cause allergic reactions.

beta adrenergic blocker eye drops

Eye drops that reduce intraocular pressure (IOP) by decreasing the production of aqueous humor through inhibiting beta adrenergic receptors, a part of the unconscious nervous system, includes timolol, carteolol, betaxolol, levobunolol.

betaxolol (Betoptic)

A beta adrenergic blocker eye drop.

Betimol (timolol)

A beta adrenergic blocker eye drop


Eyeglasses with lenses that correct both distance and near vision. Many versions have no dividing line and permit continuously changing power of the lens to allow clear vision in middle distances by positioning the head appropriately (called progressive lenses).


The visible zone on the upper white part of the eye where glaucoma surgery called trabeculectomy has been performed, often slightly elevated and paler than the surrounding tissues.

Bonnet phenomenon

Visual hallucinations caused by substantial vision loss from glaucoma and other eye diseases, due to large areas of missing vision.

brimonidine (Alphagan P)

An alpha adrenergic agonist eye drop.

brinzolamide (Azopt)

A carbonic anhydrase inhibitor eye drop.

carbonic anhydrase inhibotors

Eyedrops or pills that decrease the production of aqueous humor by inhibiting a chemical (enzyme) in the ciliary body.

carteolol (Ocupress)

A beta adrenergic blocker eye drop.


Haziness or clouding of the lens in the eye that can be removed by surgery.

central corneal thickness (CCT)

The thickness of the clear front tissue of the eye, which changes the eye pressure reading when it is thicker or thinner than average.

central vision

The portion of the visual system that does fine, detailed vision.


The layer of the eye between the sclera and the retina, containing many blood vessels.

choroidal expansion

Thickening of the choroid, which plays a role in causing forms of angle closure and angle closure glaucoma. Sometimes referred to as choroidal detachment.

ciliary body

The part of the eye that makes aqueous humor, found just behind the iris.


A laser procedure done in the operating room to lower pressure by decreasing production of aqueous humor.


Receptor nerve cells in the retina that capture light and perform detailed vision and color vision.


The membrane covering the front surface of the eye outside the cornea, like plastic sandwich wrap with blood vessels, that forms the bleb to soak up aqueous humor after trabeculectomy surgery.

continuous wave laser (argon or diode type)

Laser used to treat either the angle or the ciliary body to decrease eye pressure.


The clear front portion of the eye, shaped in a near circle about 12 millimeters in diameter.


Medicines that are based on normal body hormones, used to decrease inflammation, and often a cause of higher eye pressure when taken as pills, nasal sprays, or inhalers.

decibel (dB)

The units used in the visual field test that measures how much side vision is lost in glaucoma.

diabetes mellitus

A general body disease of unresponsiveness to or lack of insulin that can lead to a form of secondary glaucoma due to growth of abnormal blood vessels (neovascular glaucoma). Formerly thought to be a contributor to open angle glaucoma, but now known not to be.

laser ciliodestruction

A laser procedure done in the operating room to lower pressure by decreasing production of aqueous humor.

dipivefrin (Propine)

An alpha adrenergic agonist eye drop

dorzolamide (Trusopt)

A carbonic anhydrase inhibitor eye drop

dry eye syndrome

A very common cause of stinging, burning, red eyes, initially treated by use of over the counter artificial tears.


A medical term for swelling. When the retina swells in the part that governs reading, it is called macular edema. When the cornea is swollen from high eye pressure, it is corneal edema.


Serious infection caused by bacteria, virus or fungus in the inside of the eye.


A preferred term for what is sometimes called race. In this guide, we use the continent from which ancestors of the person came to describe their dominant genetic background, such as, African-derived.

exfoliation syndrome

A disorder that often leads to open angle glaucoma in which cells produce a fibrous white material that accumulates inside the eye and blocks aqueous outflow. Also called pseudoexfoliation.


Also called hyperopia, this form of needing glasses is seen in persons with smaller than average eyes. A contributing factor in angle closure glaucoma.

filtration surgery

The term used for surgeries like trabeculectomy, indicating that aqueous humor filters out of the eye through a created opening.

fiber (nerve fiber)

The long part of a ganglion cell or other neuron that carries its electrical signal on to the next neuron. Also called the axon.

fluorescein angiography

The long part of a ganglion cell or other neuron that carries its electrical signal on to the next neuron. Also called the axon.

ganglion cells

The nerve cells in the retina of the eye that die in glaucoma, causing its vision loss.


The units of inherited traits made of deoxyribonucleic acid (DNA) and found in the center of most cells. All the genes in a person together are their genome.

gene therapy

Possible new treatments for glaucoma, some called neuroprotection, involving the insertion of new genes or DNA into cells in the eye, carried there by modified virus particles.


A bothersome problem, especially for those with glaucoma, in which too much light hits the eye and, by scattering inside the eye, causes decreased ability to see effectively.


The examination technique used to see the angle in the front of the eye to distinguish between open angle and angle closure in glaucoma. The lens used is called a gonioscope.


The eye disease in which ganglion cells die in a characteristic pattern, with specific deepening of the optic nerve head structure and particular loss of peripheral visual field. The primary forms are open angle and angle closure glaucoma.


Leakage of blood from blood vessels.


A medicine given to prevent blood clotting, which must be taken into account when eye surgery is planned.


Also known as farsightedness. A contributing factor in angle closure glaucoma.

iCare tonometer

An instrument to measure eye pressure that does not require anesthetic drops to be used first. Helpful in measuring pressure in children and those with unusual corneas.

inflammatory glaucoma

A form of secondary glaucoma caused by inflammation in the eye (uveitis).

intraocular pressure (IOP)

The difference between the fluid pressure inside the eye and atmospheric pressure outside, produced by the balance between the amount of aqueous humor made by the ciliary body and the amount flowing out of the trabecular meshwork and the uveoscleral outflow pathway.


a treatment with laser to alter the shape of the iris, used in a condition called plateau iris syndrome.


An opening produced in the iris, most often by laser treatment, for angle closure and angle closure glaucoma. Similar to iridectomy which is performed in the operating room with instruments in the eye.


The colored part of the eye whose central opening or pupil allows light into the eye. Muscles in the iris allow the pupil to get bigger in dim light and small in bright light.

Istalol (timolol)

A beta adrenergic blocker eye drop.

lamina cribrosa

The colored part of the eye whose central opening or pupil allows light into the eye. Muscles in the iris allow the pupil to get bigger in dim light and small in bright light.

laser trabeculoplasty

A treatment for glaucoma that involves treating the trabecular meshwork with up to 100 deliveries of laser energy, either argon laser trabeculoplasty (ALT) or selective laser trabeculoplasty (SLT), to improve outflow of aqueous humor and lower eye pressure.


The clear structure found behind the iris in the eye that helps to focus images on the retina. When becomes cloudy it is called a cataract.

levobunolol (Betagan)

A beta adrenergic blocker eye drop to lower eye pressure

low tension glaucoma

A term that is now known to be incorrect, referring to the many persons with open angle glaucoma who never have eye pressure higher than the range found in the population who do not have glaucoma. Also normal tension glaucoma.

Lumigan (bimatoprost)

A prostaglandin eye drop to lower eye pressure.

malignant glaucoma

A form of angle closure glaucoma that involves collapse of the vitreous humor in the back chamber of the eye.


A mixture of plant material that remains federally illegal that lowers eye pressure when eaten or smoked. Not considered to be an effective treatment for glaucoma.

methazolamide (Neptazane)

A carbonic anhydrase inhibitor medication used as a pill to lower eye pressure.


A medicine placed on the eye at the time of trabeculectomy glaucoma surgery to improve the success at lowering eye pressure.


Also myopic or near-sighted, the condition where one can see better without glasses up close compared to far away. Myopic eyes are larger than normal and more susceptible to open angle glaucoma.


A protein found in the eye that is associated with a rare form of open angle glaucoma when it is mutated or changed by an inherited condition.

neodymium:YAG laser

The laser that is most often used to make a hole in the iris (iridotomy) to treat angle closure glaucoma.

neovascular glaucoma

A form of secondary glaucoma that comes from new blood vessels growing in the angle to block outflow of aqueous humor, often associated with diabetes mellitus or blocked blood vessels in the retina.


A potential future form of glaucoma treatment in which retinal ganglion cells will live longer due to treatments that are not related to lowering the eye pressure.

normal tension glaucoma

An outmoded term referring to those with open-angle glaucoma who have normal intraocular pressure. Also called low tension glaucoma.

ocular hypertension

Refers to an eye that has eye pressure higher than that typically found in the general population. A contributing factor in most forms of glaucoma.

open angle

The space between the iris and the cornea on the interior of the eye, a circular zone running all around the front of the eye, which is open when the iris is not near the cornea, allowing aqueous humor to flow out easily.

open angle glaucoma

The most common form of glaucoma, found in eyes with open angles.


A physician and surgeon (medical doctor - M.D.) who specializes in the diagnosis, treatment, and surgery of eye diseases.


The examination of the inside of the eye, particularly the optic nerve head and nerve fiber layer, during which damage from glaucoma is visible. Performed with bright lights, a binocular viewing instrument (slit lamp) and hand-held lenses by the eye doctor.

optic nerve head

The opening in the back wall of the eye (sclera) that permits fibers of retinal ganglion cells to pass from inside the eye outward to the brain. The location at which fibers are damaged in glaucoma.

optic nerve

The fibers of ganglion cells after they have left the eye, carrying visual images into the brain on the way to the next relay station in the vision system.


A technician who fits and manufactures eyeglasses and contact lenses.


Inherited defects in this protein in the eye are linked to some forms of open angle glaucoma in a small number of persons.


A specialist who is trained in the diagnosis of eye diseases and is permitted to prescribe eye drops for glaucoma in the United States.


Measurement of the thickness of the center of the cornea (central corneal thickness or CCT), useful in estimating the accuracy of eye pressure measurement.

panretinal photocoagulation

A treatment with laser of the interior of the eye (retina) most often done to decrease new blood vessel growth in diabetes, and as an initial treatment for neovascular glaucoma.

perfusion pressure

Blood flowing into the eye is driven by the blood pressure and its entry is resisted by the eye pressure. The difference between blood pressure and eye pressure is the perfusion pressure—if it falls too low, blood does not get into the eye adequately and this is a contributing factor in some glaucoma patients.


The formal name for visual field tests that measure loss of side vision in glaucoma.

peripheral anterior synechiae

Places where the iris has permanently stuck to the trabecular meshwork due to angle closure, blocking some of the outflow of aqueous humor and causing eye pressure to be higher.

peripheral vision

The part of what we see that is not directly in the center of our visual world, and the part that is affected during the early and moderate stages of glaucoma

pigment dispersion

A condition in which the iris rubs on the structures behind it that hold the lens in place, knocking off pigmented tissue that floats in the aqueous humor and lodges in the trabecular meshwork to cause higher eye pressure.


An eye drop that lowers eye pressure by stimulating the parasympathetic nerve and muscle receptors in the eye.

plateau iris

A condition in which the iris comes close to the trabecular meshwork and seems to block outflow by having a flat, table like shape. When this plateau shape is present but no other problem is present it is called plateau iris configuration. When the eye has repeated attacks of high pressure despite a laser iris hole being made in an eye with this configuration, it is called plateau iris syndrome.


One of a number of pill medications given to thin the blood and to decrease blood clotting in several general body conditions. Persons using these medications should inform an eye surgeon prior to surgery.


Loss of the ability to see at reading distance that develops in all persons starting at age 45 or so.


The chemical(s) put in eye drops to keep bacteria from growing in the solutions. Sometimes a cause of allergy to drops.

prostaglandin eye drops

A group of eye drops commonly used to lower eye pressure in glaucoma.


Drooping of the eyelid, caused by age and made worse in some persons by eye surgery. (the “p” is silent).

pupil block

The reason that eye pressure goes high in angle closure eyes. As aqueous humor moves between the iris and lens to get from the back chamber to the front chamber of the eye, it can be blocked, causing the iris to bow forward and leading to closure of the angle.


The circular opening in center of the iris that gets bigger in the dark and smaller in bright light.

refractive surgery

Operations most commonly performed with lasers to change the need for eyeglasses. These procedures should be carried out with caution in those with glaucoma.


The innermost layer of the eye wall, that has nerve cells that perform our seeing function. Retinal ganglion cells in this layer are those that die in glaucoma.

risk factor

A feature of a person that contributes to disease, things like age, eye pressure, history of the disease in the family.


The outer wall of the eye, the white part, that determines the amount of stress delivered to ganglion cells in glaucoma. During trabeculectomy glaucoma surgery, a valve-like flap area is created in the sclera to allow aqueous to leak out slowly.

secondary glaucoma

Glaucoma that occurs to an eye due to a second problem in the eye; for example, after a substantial injury.

selective laser trabeculoplasty (SLT)

A form of laser treatment to the angle, like argon laser trabeculoplasty (ALT)

side effects

Undesirable results of taking medicine.

slit lamp

The main instrument used by eye doctors to look at the eyes, consisting of a bright light and a viewing set of lenses that look like binoculars.


The liquid on the surface of the eye that increases when we cry. Tears come from a gland on the upper, outer part of the tissues around the eye and leave from natural channels on the nose side. This is a different fluid from the aqueous or vitreous humor inside the eye and tears do not have anything directly to do with glaucoma. Not having good quality tears is a cause of dry eye, an uncomfortable condition.


The way in which the visual field test decides how well we see at each of many points that it tests. Formally, threshold is a brightness of the test light that you have a 50:50 chance of seeing against the dim background.


A beta adrenergic blocker eye drop that lowers eye pressure.

tonometer (tonometry)

The instrument (and process) that is used to measure eye pressure.

trabecular meshwork

The part of the angle through which aqueous humor flows out.


The most commonly performed surgical operation for glaucoma.


The specific operation performed in infants and children for glaucoma. An alternative operation that is similar in children is goniotomy.

travoprost (Travatan Z)

A prostaglandin eye drop to lower eye pressure.

tube (shunt)

A device consisting of a micro-tube connected to a reservoir that are sewn into the front chamber of the eye and attached outside the eye to allow aqueous to drain out in a surgical procedure.

ultrasonic biomicroscopy

An examining method that produces a picture of the inside structures of the eye by using painless sound waves.

unilateral trial

The method in which eye drops are tested for their effect by using them in one eye only for a while. When drops are stopped in one eye to see if they are working, it is a unilateral stop trial.


A group of conditions in which there is inflammation inside the eye, sometimes causing a secondary glaucoma.

uveoscleral pathway

A second way that aqueous humor leaves the eye (in addition to the trabecular meshwork). It is a pathway through the space between the sclera and the choroid.


An operation that removes the vitreous humor from the back chamber of the eye, which is needed as the treatment for malignant glaucoma, an unusual form of angle closure.

visual field test

The test used to tell if glaucoma has caused damage to the ability to see, most concentrated in the middle peripheral vision, more formally known as perimetry.

vitreous humor

A gooey substance that fills the back 3/4ths of the eye, and a contributing factor in malignant glaucomaa.


The solution in which eye drop medicines for glaucoma are dissolved, including the water in the bottle and chemicals to preserve the drug and keep it effective.

warfarin (Coumadin)

A drug used to thin the blood, to prevent clotting in a group of general body diseases. Patients taking this medicine should tell their eye doctors before having surgery.

Xalatan (latanoprost)

A prostaglandin eye drop to lower eye pressure.

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