What is Glaucoma?
Glaucoma encompasses a number of conditions that are characterized by a particular pattern of blindness involving optic nerve damage and visual field loss. Most, but not all, of the conditions involve increased intraocular pressure (IOP) within the eye, which is by far, the most common risk factor for vision loss due to glaucoma. This increased pressure damages the optic nerve and can result in a progressive loss of peripheral vision leading to blindness if not properly diagnosed and treated.
It is a serious condition of the eye affecting approximately two percent of the population. It has robbed millions of people of their eyesight. If left untreated, it can cause total, irreversible blindness. Glaucoma can strike anyone, but it need not cause blindness. If glaucoma is found early and treated properly, your eyesight can be preserved. Early diagnosis is the key to prevention of blindness from glaucoma.
Glaucoma is characterized by optic nerve damage and visual field loss. Typically, it involves increased pressure inside the eye that affects the delicate tissues of the optic nerve.
Early detection and treatment are the keys to preventing unnecessary vision loss.
Types And Causes 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 characterized 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.
Other Types of Glaucoma
Not all types of glaucoma are 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. It is believed that poor blood flow to the optic nerve causes this condition. Eyes afflicted with this condition are far more susceptible to optic nerve damage with any increase in the intraocular pressure than other eyes are. Only recently have scientists recognized how common normal-tension glaucoma is and begun research into its causes and treatment.
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 characterized 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.
Testing And Treatment For Glaucoma
Glaucoma can be diagnosed by a simple and painless measurement of pressure in the eye. This test is called tonometry.
Persons diagnosed with glaucoma, or those persons exhibiting some of the symptoms of glaucoma (glaucoma suspects), are routinely followed with frequent tonometry tests to measure the pressure inside the eye. To monitor the effects glaucoma is having upon the optic nerve and the person's overall vision, optic nerve photography and visual field testing are performed at regular intervals. The information from these tests gives an indication of the effectiveness of the treatment being used and whether stronger measures are in order.
The treatment for glaucoma depends upon the nature and severity of each case. Commonly, open angle glaucoma can be controlled by daily eye drops or oral medications. If these medications fail to lower the pressure inside the eye, laser therapy or surgery to relive the pressure will be necessary. Selective Laser Trabeculoplasty (SLT) is a new treatment which does not rely on medicines, instead, uses an advanced laser system to target only specific cells of the eye-those containing melanin, a natural pigment. This allows for only these cells to be affected, leaving surrounding tissue intact. As a result, your body's own healing response helps lower the pressure in your eye.
It is important to remember that the vision lost due to damage to the optic cannot be restored. Medications, laser treatments, and surgery can only prevent further loss of sight. Glaucoma cannot be cured, but it can be controlled.