There are actually a number of types of Glaucoma. To best understand these different types of Glaucoma it is important to learn about how the normal eye functions. In the “normal” eye, there is a continuous production and drainage of clear colorless fluid called “Aqueous Humor”. This production and drainage is balanced-that is, an equal amount is produced and drained-so as to maintain a “normal’ Intraocular Pressure (IOP).

In the event that there is either too much Aqueous Humor being produced or too little Aqueous Humor is being drained, there is a rise in pressure inside the eye, called the Intraocular Pressure (IOP). An elevation of Intraocular Pressure (IOP) is considered “abnormal” as it is best to have equilibrium of Aqueous Humor fluid so that a “normal” pressure in the eye is maintained.

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). 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.

Since Primary Open Angle Glaucoma and Angle Closure Glaucoma are the most common, we will limit our discussion to these types of Glaucoma.

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. 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. 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. This is the nature of Primary Open Angel Glaucoma.

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.

Primary Angle Closure Glaucoma accounts for approximately 10% of all cases of Glaucoma and about 2/3 of these once again produce no 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 called 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. Acute Angle Closure Glaucoma is characterized by this sudden rise in pressure which will 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 therefore 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 Riverside Eye Center at 207.743.0027 and relay these symptoms to the receptionist so that you can be given an appointment immediately.

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 when the Crystalline Lens begins to swell.

During your general eye exam if Dr. Whitaker observes or measures a narrowed angle, he will perform an additional examination procedure called Gonioscopy. This will allow him to directly examine the Trabecular Meshwork and the angle in order to carefully assess your predisposition to Angle Closure Glaucoma. By placing a special contact lens on your eye and then using the slit lamp biomicroscope to fully examine the meshwork and the angle with Gonioscopy Dr. Whitaker will be able to make a thorough evaluation.

In the event that you are at risk for Angle Closure Glaucoma or in the event that you have Acute Angle Closure Glaucoma Dr. Whitaker may initially prescribe some medication to begin to lower the pressure. Also, he 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. Dr. Whitaker performs Laser Iridotomy right in the comfort and convenience of our office.

Glaucoma is a very complex eye disease, and not simply an elevated Intraocular Pressure (IOP). Nonetheless, when detected early it can be successfully treated. Dr. Whitaker and the staff of Riverside Eye Center provide the full scope of advanced technology diagnostic testing and treatment, as well as taking the time necessary to give each patient the personal education needed to fully understand their condition.

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