Glaucoma

It is estimated that over two million Americans have some type of glaucoma and half of them do not know it.  Although there are many different types of glaucoma, the two more common types, Open-Angle Glaucoma and Narrow-Angle Glaucoma, will be described.

Open-Angle Glaucoma

Ninety percent of glaucoma patients have open-angle glaucoma. Although it cannot be cured, it can usually be controlled. Vision loss may be minimized with early treatment. The eye receives its nourishment from a clear fluid that circulates inside the eye.

Fluid circulating inside eye

This fluid must be constantly returned to the blood stream through the eye's drainage canal, called the trabecular meshwork. In the case of open-angle glaucoma, something has gone wrong with the drainage canal. When the fluid cannot drain fast enough, pressure inside the eye begins to build.

Excess fluid builds pressure

This excess fluid pressure pushes against the delicate optic nerve that connects the eye to the brain. If the pressure remains too high for too long, irreversible vision loss can occur.

Excess fluid pressure pushes
against the optic nerve

Symptoms of open-angle glaucoma:

• In the early stages, there are no symptoms. There is no pain or outward sign of trouble.
• Mild aching in the eyes
• Gradual loss of peripheral vision (the top, sides and bottom areas of vision)
• Seeing halos around lights
• Reduced visual acuity (especially at night, that is not correctable with glasses)

Who is at risk

Glaucoma can occur in people of all races at any age. However, the likelihood of developing glaucoma increases if you:

• are African American
• have a relative with glaucoma
• are diabetic
• are very nearsighted
• are over 35 years of age

Diagnosing open-angle and closed-angle glaucoma:

Everyone should be checked for glaucoma at around age 35 and again at age 40. Those considered to be at higher risk, including those over the age of 60 should have their pressure checked every year or two.

Tonometry is used to check your eye pressure

An ophthalmoscope is used to examine your optic nerve

Perimetry maps your field of vision

Gonioscopy is used to help your glaucoma type

Treatments for open-angle glaucoma:

To control glaucoma, your doctor will use one of three basic types of treatment: medicines, laser surgery, or filtration surgery. The goal of treatment is to lower the pressure in the eye.

Glaucoma medication comes in many forms

Medicines come in pill and eye drop form. They work by either slowing the production of fluid within the eye or by improving the flow through the drainage meshwork. To be effective, most glaucoma medications must be taken between one to four times every day, without fail. Some of these medications have some undesirable side effects, so your doctor will work with you to find a medication that controls your pressure with the least amount of side effects. Medicines should never be stopped without consulting your doctor, and you should notify all of your other doctors about the medications you are taking.

Argon Laser Trabeculoplasty (ALT) and Selective Laser Trabeculoplasty (SLT) surgery treat the drainage canal. Requiring only numbing eye drops, the laser beam is applied to the trabecular meshwork resulting in an improved rate of drainage. When laser surgery is successful, it may reduce the need for daily medications.

Endoscopic CycloPhotocoagulation (ECP) is another type of laser procedure. Instead of treating the drainage canal, it treats the ciliary body. Treating the ciliary body reduces the amount of fluid production thereby reducing the intraocular pressure. ECP is most often performed along with cataract surgery but can be done on an outpatient basis when in the best interest of the patient. The majority of patients having ECP reduce or eliminate their need to take glaucoma medications.

Filtration surgery is performed when medicines and/or laser surgery are unsuccessful in controlling eye pressure. During this microscopic procedure, a new drainage channel is created to allow fluid to drain from the eye.

Narrow-Angle Glaucoma (also called Closed-Angle Glaucoma)

Narrow-angle glaucoma is much more rare and is very different from open-angle glaucoma in that eye pressure usually goes up very fast. This happens when the drainage canals get blocked or covered over. The iris gets pushed against the lens of the eye, shutting off the drainage angle. Sometimes the lens and the iris stick to each other. This results in pressure increasing suddenly, usually in one eye. There may be a feeling of fullness in the eye along with reddening, swelling and blurred vision. 

Symptoms of narrow-angle glaucoma:

The onset of acute narrow-angle glaucoma is typically rapid, constituting an emergency. If not treated promptly, this glaucoma produces blindness in the affected eye in three to five days. Symptoms may include:

• Inflammation and pain
• Pressure over the eye
• Moderate pupil dilation that's non-reactive to light
• Cloudy cornea
• Blurring and decreased visual acuity
• Extreme sensitivity to light
• Seeing halos around lights
• Nausea and/or vomiting

Causes of narrow-angle glaucoma:

• Defect in the eye structure
• Anything that causes the pupil to dilate -- dim lighting, dilation drops
• Certain oral or injected medications
• Blow to the eye
• Diabetes-related growth of abnormal blood vessels over the angle  

Treatment for narrow-angle glaucoma:

Iridotomy for narrow-angle glaucoma

Laser iridotomy is a common treatment for narrow-angle glaucoma. During this procedure, a laser is used to create a small hole in the iris, restoring the flow of fluid to the front of the eye. In most patients, the iridotomy is placed in the upper portion of the iris, under the upper eyelid, where it cannot be seen.

Filtration surgery is performed when medicines and/or laser surgery are unsuccessful in controlling eye pressure. During this microscopic procedure, a new drainage channel is created to allow fluid to drain from the eye.