Types of Glaucoma
There are actually many different types of Glaucoma. To best understand the types of Glaucoma, it is important have some knowledge of how the “normal” eye functions.
In the “normal” eye a clear colorless fluid called “Aqueous Humor” is constantly being produced and drained at the same time. Normally there is a balance between the production and the drainage of the fluid. Since an equal amount is produced and drained, a “normal” Intraocular Pressure (IOP) is maintained.
If, either too much Aqueous Humor is produced, or too little Aqueous Humor is drained, it may result in an elevation of Intraocular Pressure (IOP). An elevation in Intraocular Pressure (IOP) is considered “abnormal” and may be an indication of Glaucoma.
The two most common types of Glaucoma are Primary Open Angle Glaucoma (POAG), and Angle Closure Glaucoma. Each of these types of Glaucoma is associated with an elevated Intraocular Pressure (IOP), or pressure inside the eye.
However, it is also possible to have damage to the Optic Nerve, even with a “normal” Intraocular Pressure. Normal Tension Glaucoma is a type of Glaucoma that is characterized by Optic Nerve damage occurring even with a normal IOP. Secondary Glaucoma refers to any situation in which another disease causes or contributes to increased eye pressure, resulting in Optic Nerve damage and vision loss.
As Primary Open Angle Glaucoma and Angle Closure Glaucoma are the most common types of Glaucoma, we will limit our discussion to those types of Glaucoma.
Primary Open Angle Glaucoma
Primary Open Angle Glaucoma (POAG) is the most common type of Glaucoma. Patients with Primary Open Angle Glaucoma typically have an increase in Intraocular Pressure (IOP). The increased Intraocular Pressure (IOP) results from either too much Aqueous Humor being produced or too little being drained as discussed earlier. 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 become compromised, depriving it of oxygen and nutrients, resulting in permanent changes and even 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 transmitting 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 slow, progressive and permanent damage to the optic nerve that can result in blindness from Glaucoma.
Angle Closure Glaucoma
Angle Closure Angle Closure Glaucoma consists of two subtypes of Glaucoma which include Primary Angle Closure Glaucoma and Acute Glaucoma. Even though Angle Closure Glaucoma occurs much less frequently than Open Angle Glaucoma, it is important to be familiar with Angle Closure 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 instances occur without producing noticeable 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, which is called the Trabecular Meshwork. The Trabecular Meshwork is actually a fine filter. If the Trabecular Meshwork 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 (IOP) to rise. In instances where the meshwork becomes blocked suddenly, 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 can cause distinct symptoms that include pain, light sensitivity, redness, blurred vision, colored haloes around lights and nausea or vomiting. Angle Closure Glaucoma is one of the only types of Glaucoma that produces symptoms such as these.
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 swell.
During your general eye exam if your Coastal Eye Care physician observes or measures a narrowed angle, he will perform an additional examination procedure called Gonioscopy. This will allow him to fully visualize the meshwork and the angle in order to carefully assess your predisposition to Angle Closure Glaucoma. Gonioscopy is performed by placing a special contact lens on your eye and then using the slit lamp biomicroscope to fully examine the meshwork and the angle.
If you are at risk for Angle Closure Glaucoma or in the event that you actually have Acute Angle Closure Glaucoma your Coastal Eye Care physician 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. Laser Iridotomy is performed right in the offices of Coastal Eye Care with minimal if any discomfort or recovery time required.
Glaucoma is a very complex eye disease, and not simply an elevated Intraocular Pressure (IOP). Nonetheless, when detected early it can be successfully treated. At Coastal Eye Care in Maine, our eye physicians and staff provide the full scope of advanced technology diagnostic testing and treatment for all types of Glaucoma, as well as taking the time necessary to give each patient the personal education needed to fully understand their condition in order to get the best possible outcomes for our patients.
If you, a family member or friend are at risk for Glaucoma or need an eye examination and Glaucoma evaluation, Coastal Eye Care provides advanced testing for the diagnosis and treatment of all types of Glaucoma and is conveniently located in Ellsworth, Maine for Eastern Maine and Downeast Maine eye care patients.
To schedule an appointment for a Glaucoma evaluation, please call Coastal Eye Care in Maine at 207.667.6300.
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