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Types of Glaucoma:

Open Angle Glaucoma & Angle Closure Glaucoma

There are two main types of Glaucoma: Primary Open Angle Glaucoma (POAG), and Angle Closure Glaucoma. Both are characterized by an elevated  Intraocular Pressure (IOP), or pressure inside the eye. Sometimes it is possible to have damage to the optic nerve, even with a “normal” Intraocular Pressure. When optic nerve damage has occurred despite a normal IOP, this is called Normal Tension Glaucoma. Secondary Glaucoma refers to any case in which another disease causes or contributes to increased eye pressure, resulting in optic nerve damage and vision loss. Primary Open Angle Glaucoma and Angle Closure Glaucoma are the most common types of Glaucoma and thus we will limit our discussion to these.

Primary Open Angle Glaucoma

The most common type of Glaucoma is Primary Open Angle Glaucoma (POAG). Patients with Primary Open Angle Glaucoma usually have an increase in Intraocular Pressure (IOP) upon routine measurement, called Tonometry. This increased Intraocular Pressure (IOP) results from either too much Aqueous Humor being produced or too little being drained through the Trabecular Meshwork. The fluid buildup within the closed space of the inside of the eye causes the pressure to rise. This elevation in pressure (IOP) causes the circulation in the optic nerve to decrease, depriving it of oxygen and nutrients, resulting in permanent damage to the optic nerve resulting in vision loss. The optic nerve is the connection between the retina and the brain and is responsible for communicating visual images. Once the optic nerve is damaged, it is not able to carry visual images, resulting in vision loss. This is why it is so important to monitor, detect and control Intraocular Pressure (IOP). If left untreated, an elevated Intraocular Pressure (IOP) may, over time, cause total blindness.

Angle Closure Glaucoma

Angle Closure Angle Closure Glaucoma can be divided in two main types: Primary Angle Closure Glaucoma and Acute Angle Closure Glaucoma. Although Angle Closure Glaucoma is occurs much less frequently than Open Angle Glaucoma, it is important to understand it because it has the ability to produce considerable vision loss in a short period of time.

Primary Angle Closure Glaucoma accounts for approximately 10% of all cases of Glaucoma and about 2/3 of these once again produce no early symptoms for patients.

Acute Angle Closure Glaucoma is one of the only types of Glaucoma that produce distinct symptoms that include pain, light sensitivity, redness, blurred vision, colored haloes around lights and nausea or vomiting.

Angle Closure Glaucoma is characterized by a blockage or complete closure of the drainage structure of the eye-the Trabecular Meshwork. The Trabecular Meshwork is actually a fine filter. If it is blocked or obstructed by any alteration in the size or shape of the surrounding structures, or by change in the size or shape of the tissue itself, it will cause the Intraocular Pressure to elevate. In instances where the meshwork becomes blocked abruptly, it will cause a sudden rise in the Intraocular Pressure (IOP), resulting in Acute Angle Closure Glaucoma. Angle Closure Glaucoma is characterized by this sudden rise in pressure which will can cause pain, redness, blurred vision and if left untreated permanent loss of vision.

While there can be a several causes of Angle Closure Glaucoma, it is most often caused by anatomical changes within the internal structures of the eye. Angle Closure Glaucoma is considerably more common in farsighted eyes, which tend to be smaller and in patients between the ages of 45-60 years of age where the Crystalline Lens is beginning to swell.

In the event that you are at risk for Angle Closure Glaucoma or in the event that you have Acute Angle Closure Glaucoma your eye doctor may initially prescribe some medication to begin to lower the pressure and then will most likely recommend performing a type of Laser Eye Surgery in order to produce a small opening or hole in the Iris so that Aqueous Humor can quickly and efficiently drain from the eye. This procedure, called a “Laser Iridotomy,” is quite successful in treating Angle Closure Glaucoma and preventing recurrences.

angle closure glaucoma, glaucoma laser, PI, Laser Iridotomy

About Glaucoma
Glaucoma Risk Factors
Types of Glaucoma: Open Angle Glaucoma & Angle Closure Glaucoma
Testing & Diagnosis of Glaucoma
Medical, Laser & Surgical Treatment of Glaucoma
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©2011 The Medical Management Services Group

updated 2/27/11