Types of Glaucoma
Although there are many types of glaucoma, ophthalmologists typically group them into two main categories: open-angle glaucoma and angle-closure glaucoma. Forms of glaucoma in both categories are characterized by damage to the optic nerve which can eventually lead to blindness.
Open-angle glaucoma is the most common type of glaucoma, but there are different forms. In all forms of open-angle glaucoma, there is something wrong with the drainage angle of the eye even though it appears to be open and appears normal in microscopic exams. The drainage angle is where the iris (the colored part of your eye) meets a tissue called the trabecular meshwork.
Primary Open-Angle Glaucoma
In primary open-angle glaucoma, the drainage angle of the eye is open but does not allow fluid, called aqueous humor, to drain adequately. This results in the eye’s drainage system becoming clogged over time, leading to a slow increase in intraocular pressure. This type of glaucoma is painless and often goes unnoticed until damage to the optic nerve becomes more severe with some people losing their vision before they are aware there is a problem. Primary open-angle glaucoma can run in families and is more common in African Americans.
Also called normal-tension glaucoma, low-pressure glaucoma is characterized by damage to the optic nerve and vision loss despite intraocular pressure not being elevated above average level. Low-pressure glaucoma is also known to result from poor blood flow to the optic nerve and is associated with a variety of conditions including migraines, Raynaud’s disease, and sleep apnea.
Congenital glaucoma is a form of the disease that occurs in infants and very young children due to abnormal development of the drainage angle of the eye. Symptoms of congenital glaucoma often include light sensitivity, watery eyes, or a tendency to keep the eyes closed. The eyes may also appear larger than normal and have cloudy corneas.
Types of Secondary Open-angle Glaucoma
There are many different types of secondary open-angle glaucoma. Usually, these forms of glaucoma result from abnormal deposits of material in the drainage angle, medications (specifically steroids), or trauma.
Pseudoexfoliative glaucoma is caused by the accumulation of a fibrillary, protein material in the drainage angle and other structures of the eye. This prevents adequate drainage of fluid from the eye. Pseudoexfoliative glaucoma is most common in adults of northern European descent.
In pigmentary glaucoma, pigment dislodged from the iris slowly builds up in the eye’s drainage systems and causes intermittent increases in intraocular pressure. Pigment granules can be dislodged from physical activities such as jogging. This is one of the few types of glaucoma that occurs in young people, most often young, nearsighted men.
In angle-recession glaucoma, physical injury to the drainage angle impairs its ability to remove fluid from the eye. This type of glaucoma can develop years, or even decades, after the original eye injury.
Topical or systemic treatment with steroid medications, such as prednisone, can cause intraocular pressure to increase. In some cases, the increase in pressure is great enough or lasts long enough to cause glaucoma-related optic nerve damage and vision loss. This is known as steroid-induced glaucoma.
Angle-closure glaucoma may also be called primary angle-closure glaucoma, closed-angle glaucoma, or narrow-angle glaucoma. In these forms of glaucoma, a mechanical problem exists with the drainage angle of the eye. This means the iris is too close to the trabecular meshwork. This causes blockage of the drainage angle that prevents fluid from being properly drained from the eye.
Acute Angle-Closure Glaucoma
When the drainage angle of the eye becomes suddenly and completely blocked, intraocular pressure rises very quickly. This is called an acute angle-closure attack. In acute angle-closure glaucoma, this rapid onset of pressure can cause blindness in a matter of hours, however, it can be prevented or terminated by a sight-saving laser treatment called laser iridotomy.
Signs that you may be experiencing an acute angle-closure glaucoma attack include:
- Suddenly blurry vision
- Eye redness
- Severe eye pain
- Seeing rainbow-colored rings or halos around lights
These symptoms are often mistaken for a migraine headache or another non-glaucoma related vision problem. They can also be precipitated by certain medications you may be taking. Some ingredients in many over the counter cold symptom relief medications and prescription medications for various conditions can make a susceptible patient more likely to suffer acute angle-closure glaucoma. Patients with these symptoms need a careful evaluation of the drainage angle of their eyes to determine if they are at risk for angle-closure glaucoma.
Chronic Angle-Closure Glaucoma
Unlike an acute attack, chronic angle-closure glaucoma is characterized by a slow, progressive obstruction of the eye’s drainage angle. In this form of glaucoma, symptoms are not present until the damage becomes more severe or an acute attack occurs. Chronic angle-closure glaucoma is more common in farsighted individuals.
Secondary Angle-Closure Glaucoma
Secondary angle-closure glaucoma often occurs as the result of trauma or systemic conditions that block the angle. Like the primary forms of angle-closure glaucoma, secondary angle-closure glaucoma can be either acute or chronic.
Various disorders, including diabetes, can cause blood vessels to proliferate on the iris and in the eye’s drainage structures. This accumulation of blood vessels can obstruct the drainage angle and lead to neovascular glaucoma.
Glaucoma Treatment at Dean McGee Eye Institute
The many forms of glaucoma can be treated and controlled if caught early. If you or a loved one are experiencing glaucoma symptoms, trust the doctors at the Dean McGee Eye Institute to save your vision. Call 405.271.1093 or 800.787.9015 to schedule an appointment.