Glossary Of Terms

Acute Glaucoma:

In angle-closure glaucoma, the aqueous fluid behind the iris does not flow properly into the anterior chamber, and causes the iris to be pushed forward toward the angle, thereby obstructing it.

Angle-Closure Glaucoma:

A form of glaucoma where the anterior chamber tends to be smaller than average. The ability of aqueous fluid to pass between the iris and lens on its way to the anterior chamber becomes decreased, causing fluid pressure to build up behind the iris, further narrowing the angle. When the angle is completely blocked, an acute glaucoma attack results.

Anterior Chamber:

The space in front of the iris and behind the cornea.

Aqueous:

The clear, watery fluid in the front part of your eye that flows between the lens and the cornea. This fluid nourishes the structure in the front part of your eye.

Ciliary Body:

Tissues located around the lens of your eye that produce the aqueous fluid that nourishes the eye.

Congenital Glaucoma:

A rare form of glaucoma that occurs in babies and young children. This condition can be inherited. It is usually the result of incorrect or incomplete development of the eye´s drainage canals during the prenatal period.

Cornea:

The transparent part of your outer eye that covers the iris, pupil, and anterior chamber. Part of the eye´s protective covering and focusing system.

Delayed Dark Adaptation:

Longer time duration to get acclimatised to dark surrounding especially when entering an absolutely dark room.

Drainage Canals:

Small openings around the outer edge of your iris. These canals provide the final pathway for fluid to leave the inside of the eye. (Usually referred to as the trabecular meshwork or Schlemm´s canal.)

Exfoliation Syndrome:

Small deposits within the eye that clog the trabecular meshwork, leading to elevation of the intraocular pressure, which can cause open-angle or angle closure glaucoma.

Glaucoma Suspect:

A person who might have glaucoma but it´s too early to tell. This term includes patients with ocular hypertension (persons with elevated intraocular pressure but no detectable optic nerve or visual field damage), and patients with large cup/disc ratios and normal visual fields who may or may not have early normal-tension glaucoma.

Gonioscopy:

A diagnostic test in which a lens that contains a mirror is gently placed on the eye. The mirror lets the doctor look sideways into the eye to check whether the angle where your iris meets the cornea is open or closed. This helps the doctor determine whether open-angle or angle-closure glaucoma is present.

Haloes:

Seeing coloured rings around an illuminated bulb. It can occur in patients prone for narrow angle glaucoma.

Intraocular Pressure (IOP):

The level of fluid pressure inside your eye. The most significant risk factor for glaucoma is elevated IOP. Normal intraocular pressure usually ranges from 12-21 mm Hg, although people with relatively low pressure can still have glaucoma (see normal tension glaucoma) and people with high pressure can still have healthy eyes.

Iris:

The colored ring of tissue suspended behind the cornea and immediately in front of the lens. Expands and contracts to adjust the size of the pupil, allowing the correct amount of light to enter the eye.

Laser Surgery:

A type of surgery in which a tiny beam of focused light is used to treat problems in the eye. There are four common forms of laser surgery for glaucoma: Laser Iridotomy, Laser Iridoplasty, Laser Trabeculoplasty and Laser Cyclophotocoagulation.

Lens:

The transparent, double convex (outward curve on both sides) structure suspended between your eye´s aqueous and vitreous. Located behind the iris, this helps bring rays of light to focus on the retina. It is similar to the lens of a camera.

Low Vision:

Visual loss or difficulty that cannot be corrected with eyeglasses or contact lenses and can interfere with daily living activities.

mm Hg:

An abbreviation for `millimeters of mercury,´ which is a scale for recording intraocular pressure.

Normal Tension Glaucoma:

Also known as low tension glaucoma. Characterized by progressive optic nerve damage and visual field loss with a statistically normal intraocular pressure. It may be related to poor blood flow to the optic nerve or other factors, which lead to death of the cells.

Open-Angle Glaucoma:

This is the most common type of glaucoma. Normally associated with increased intraocular pressure, which can lead to visual field loss and optic nerve damage. There is no visible abnormality with the trabecular meshwork, however the aqueous fluid is unable to flow correctly.

Ophthalmoscopy:

An exam where your eye doctor uses an instrument called an ophthalmoscope to look directly through your eye at the optic nerve. The color and appearance of the optic nerve can indicate whether or not damage from glaucoma is present and how extensive it is.

Optic Nerve:

The bundle of nerve fibers that carry visual messages from your retina to your brain.

Perimetry:

A diagnostic exam also known as the visual field test, which produces a map of the complete field of vision, to measure the degree of damage to your vision.

Peripheral Vision:

The ability to see objects and movement outside the direct line of vision. Also know as side vision, they are usually the first areas of vision affected by glaucoma.

Pigmentary Glaucoma:

A type of open-angle glaucoma where the pigment layer of the iris rubs onto the lens causing iris pigment particles to shed and plug the pores of the trabecular meshwork, thereby increasing intraocular pressure.

Pupil:

The black circular opening in the center of your iris, which adjusts in size to regulate the amount of light entering the inner part of your eye.

Retina:

The part of the eye that converts images from your eye´s optical system into electrical impulses to the brain through the optic nerve.

Tonometry:

The use of a tonometer to measure the fluid pressure in your eye.

Trabecular Meshwork:

Small openings around the outer edge of your iris. These canals provide the final pathway for fluid to leave the inside of the eye. (Usually referred to as the trabecular meshwork or Schlemm´s canal.)

Trabeculectomy:

A form of traditional surgery where the surgeon removes a small section of the trabecular meshwork -- the eye´s drain. This allows the aqueous humor to drain more easily, reducing the pressure in the eye.

Trauma-Related Glaucoma:

A blow to the eye, chemical burn or penetrating injury may lead to the development of glaucoma, in either acute or chronic forms. This can be due to a mechanism disruption or physical change within the eye´s drainage system.

Visual Field:

The entire area that can be seen when your eye is looking forward, including any side vision.

Visual Field Test:

A diagnostic exam also known as the visual field test, which produces a map of the complete field of vision, to measure the degree of damage to your vision.

Yag Iridotomy:

It is an out-patient procedure in which a small laser treatment is used to make a small opening in the iris to enable the fluid to flow more freely.