Glaucoma is the second leading cause of blindness in the world, and in the U.S., about 3 million adults suffer from the disease – yet only about half of them know it, according to data from The Eye Diseases Prevalence Research Group. That’s because glaucoma tends to cause few symptoms – and often none – until vision loss occurs, and unless you have comprehensive dilated eye exams on a regular basis, the disease can be difficult to detect.
Glaucoma occurs when the pressure inside the eye – the intraocular pressure, or IOP – increases, causing damage to the optic nerve head located at the back of the eye. Once damaged, the nerve’s ability to send image signals to the brain for “interpretation” is forever impaired, and permanent vision loss occurs. IOP increases when fluid inside the eye, called the aqueous humor, no longer drains properly, and treatment for glaucoma focuses on reducing the pressure that builds up as this fluid collects.
THREE TYPES OF GLAUCOMA
In a healthy eye, the aqueous humor from the back portion of the eye drains into the front portion of the eye via a small, angled opening between the iris and the cornea. In people with glaucoma, the drainage mechanism becomes partially or completely blocked, resulting in two primary types of glaucoma:
- Open-angle, which is the most common, occurs when the tissue through which the fluid drains becomes clogged, inhibiting the ability of the eye to drain. In open-angle glaucoma, pressure builds up slowly over time, and vision loss is very subtle at first.
- Angle-closure glaucoma (or closed-angle glaucoma) develops when the iris pushes forward slightly, blocking the drainage channel completely. Angle-closure glaucoma can occur slowly or it can develop very rapidly.
A third type of glaucoma, called normal-tension glaucoma, develops when the IOP is still within the normal range. The causes of normal-tension glaucoma aren’t well understood, but some researchers believe it can be related to atherosclerosis, or so-called hardening of the arteries. People with very sensitive optic nerves may also be more prone to developing this type of glaucoma.
There is a fourth, far less common type, called pigmentary glaucoma, which occurs when pigment granules from the iris begin to build up inside the drainage channels, blocking them.
Understanding the differences between these types is important, because different types of glaucoma can be managed differently.
Although there’s no cure for glaucoma and the vision loss that occurs is permanent, there are things that can be done to help normalize intraocular pressure and prevent future glaucoma-related vision loss from occurring. Prescription eye drops are often the first step in treating open-angle glaucoma. Applied regularly, these drops help lower the pressure inside your eye to reduce the risk of damage to the optic nerve. Drops work by either reducing the production of eye fluid or by increasing the outflow of fluid from the interior chamber of the eye, or both. Oral medications may also be prescribed to help reduce intraocular pressure, especially if drops aren’t effective or when IOPs are quite high.
If drops and oral medicines don’t work, surgery can be performed to improve drainage. Today, there are several types of surgery for glaucoma, including those that use lasers to open or widen drainage channels, as well as surgeries to insert special drainage tubes or to clear material that has built up inside the drainage channels.
Treatment for angle-closure glaucoma is more aggressive since the condition can progress very quickly, and often involves both medication and surgery.
While glaucoma surgery is performed quite often and is considered to be extremely safe, some types of surgery may increase the risk for cataract development, and as with any type of surgery, it’s important to understand the potential risks associated with glaucoma surgery.
DEVELOPING A TREATMENT PLAN FOR YOU
At Sealy Eye Center, our team of eye care professionals is skilled in diagnosing glaucoma using state-of-the-art testing to measure eye pressure and check for changes inside the eye that can help identify the disease in its very early stages, as well as identify changes associated in normal-tension glaucoma, when pressure is not significantly increased. Because glaucoma can progress at different rates in different people, each treatment plan will be carefully developed based on the individual patient’s unique needs to ensure the best possible outcome.
Screening for glaucoma is simple and painless, and treating the disease and avoiding permanent vision loss depends on having regular comprehensive eye exams with dilation. If you haven’t had a vision exam lately, or if you’ve been experiencing any vision problems or changes in your vision, putting off treatment can result in serious consequences, including permanent loss of vision. Keep you eyes as healthy as possible.