Types of Glaucoma
There are many types of Glaucoma. However, there are two main types of Glaucoma: Primary Open Angle Glaucoma (POAG) and Angle Closure Glaucoma. Sometimes it is possible to have damage to the optic nerve, even with a “normal” Intraocular Pressure (IOP) which 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. We will limit our discussion to Primary Open Angle Glaucoma and Angle Closure Glaucoma.
Primary Open Angle Glaucoma
The most common type of Glaucoma is Primary Open Angle Glaucoma (POAG). In the “normal” eye, there is a continuous production and drainage of a clear colorless fluid called “Aqueous Humor”. This production and drainage is balanced so that an equal amount is produced and drained in order to maintain an equilibrium resulting in a “normal’ Intraocular Pressure (IOP). Patients with Primary Open Angle Glaucoma usually have an increase in Intraocular Pressure (IOP) upon routine measurement, called Tonometry.
Primary Open Angle Glaucoma is secondary to a decrease in the ability of the eye to drain the aqueous fluid. Any elevation of Intraocular Pressure (IOP) is considered “abnormal. This elevation in pressure (IOP) causes the circulation in the optic nerve to become compromised, depriving it of oxygen and nutrients, resulting in permanent changes and even damage to the optic nerve. Any damage to the optic nerve can result in a loss of vision. The optic nerve is the connection responsible for communicating visual images between the retina and the brain. When 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 slow, progressive and permanent damage to the optic nerve that can result in 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 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. 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 called the Trabecular Meshwork. 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. Acute Angle Closure Glaucoma is characterized by a sudden rise in pressure which can cause pain, redness, light sensitivity, colored haloes around lights, nausea or vomiting and blurred vision, and if left untreated permanent loss of vision.
Acute Angle Closure Glaucoma is considered a medical emergency. If you experience a sudden onset of pain, redness, blurred vision, light sensitivity, haloes around lights, nausea and vomiting, please call The Eye Care & Surgery Center at 908-789-8999 and relay these symptoms to the receptionist so that you can be given an appointment immediately.
While there can be 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 enlarge.
During your routine eye exam if one of The Eye Care & Surgery Center eye physicians observes or measures a narrowed angle, he or she will perform an additional examination procedure called Gonioscopy. This will allow the doctor to directly examine the Trabecular Meshwork. 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. Also the doctor will most likely recommend performing a type of Glaucoma Laser procedure in order to produce a small opening or hole in the Iris so that Aqueous Humor can drain from the eye more effectively. This procedure, called a “Laser Peripheral Iridotomy” and is quite successful in treating Angle Closure Glaucoma and preventing recurrences.