Glaucoma

Glaucoma is a group of diseases that can damage the eye's optic nerve and result in vision loss and blindness. However, with early treatment, the eyes can
be protected against serious vision loss.

What is the optic nerve?

The optic nerve is a bundle of more than 1 million nerve fibers. It connects the retina to the brain. The retina is the light-sensitive tissue at the back
of the eye. A healthy optic nerve is necessary for good vision.

Are there different types of Glaucoma?

There are two main classifications of glaucoma: Open Angle Glaucoma and Closed Angle Glaucoma. The type of glaucoma relates to the cause of the increased
pressure inside the eye.

Open Angle Glaucoma: Open angle glaucoma is the most common type of glaucoma. This condition is often called Primary Open-angle Glaucoma, or POAG. It is
most often completely painless and causes a very gradual loss of peripheral vision, which may go unnoticed for many months or even years. Since it gives
no obvious warning to its victim, glaucoma is often called "the sneak thief of sight."

This form of glaucoma is characterized by an excessive production of fluid inside the eye. Although the drainage system of the eye, called the "angles,"
remain open and function properly, they are unable to remove the excess fluid at a pace sufficient to prevent a rise in pressure inside the eye.

Open angle glaucoma will usually respond well to medications when found in time. In most cases, the medication must be continued for life to keep this condition
under control.

Closed Angle Glaucoma: The second type of glaucoma is known as Closed Angle Glaucoma. It is far more rare than open angle glaucoma.

This condition is characterised by blockage of the drainage system of the eye located between the iris and the lens. In many instances, the iris is pushed
forward in a condition referred to as pupillary block. This causes the iris to act like a stopper over the drain of a sink, allowing fluid levels inside
the eye to build, causing increased intraocular pressure.

Its onset can be sudden, as is the case with acute angle-closure glaucoma. A sudden onset of severe pain and a red eye are symptoms of acute angle-closure
glaucoma. Prompt intervention by the use of medications or through surgery or treatment with a laser is required to obtain relief and protect the delicate
tissues in and around the optic nerve.

In other instances, closed angle glaucoma may progress slowly over time, with the formation of scar tissue around the drainage system of the eye. This condition
is called chronic angle-closure glaucoma.

Can glaucoma develop without an increase in eye pressure?

There are other types of glaucoma that are not characterized by high intraocular pressures. In normal-tension or low-tension glaucoma, the optic nerve suffers
damage with the resulting visual field loss even though normal intraocular pressures are maintained. Exfoliation syndrome is a common form of open angle
glaucoma that results when there is a buildup of abnormal, whitish material on the lens. This material and pigment from the back of the iris plug the drainage
system of the eye, causing increased intraocular pressure. This form of glaucoma responds well to laser treatment.

Pigmentary glaucoma is a hereditary condition typically affecting young, nearsighted, Caucasian males. This condition is characterised by the iris being
too large compared to the other structures of the eye. The iris is forced to bow backwards, coming into contact with the structures holding the lens in
place. This disrupts the cells of the iris containing pigment, resulting in a release of pigment particles into the drainage system of the eye, which prompts
an increase in intraocular pressure as the drainage system becomes clogged.

Other types of glaucoma may be caused by injuries to the eye, tumors, and other eye diseases. A rare type of glaucoma can even be present in children at
birth.