Glaucoma

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Open Angle Glaucoma

It is estimated that over two million Americans have some type of glaucoma and half of them do not know it. 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. 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. 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.

Treatments for Open Angle Glaucoma

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

Medications - 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. Medications 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 and Selective Laser Trabeculoplasty - 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.

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

Symptoms of Open Angle Glaucoma

In the early stages, there are no symptoms. There is no pain or outward sign of trouble
Gradual loss of peripheral vision (the top, sides and bottom areas of vision)
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 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.

Your doctor will use tonometry to check your eye pressure. After applying numbing drops, the tonometer is gently pressed against the eye and its resistance is measured and recorded.

An ophthalmoscope can be used to examine the shape and color of your optic nerve. The ophthalmoscope magnifies and lights up the inside of the eye. If the optic nerve appears to be cupped or is not a healthy pink color, additional tests will be run.

Perimetry is a test that maps the field of vision. Looking straight ahead into a white, bowl-shaped area, you will indicate when you are able to detect lights as they are brought into your field of vision. This map allows your doctor to see any pattern of visual changes caused by the early stages of glaucoma.

Gonioscopy is used to check whether the angle where the iris meets the cornea is open or closed. This helps your doctor determine if they are dealing with open angle glaucoma or narrow angle glaucoma.

Narrow angle glaucoma is much less common and is very different from open angle glaucoma in that eye pressure usually goes up very rapidly. 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 iris stick to each other. This results in pressure increasing suddenly, usually in one eye. There may be a dull ache in the eyebrow along with reddening of the eye, halos around lights, blurred vision, and nausea and vomiting.

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 is 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

Anatomical predisposition - a "small eye"
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

Diagnosing Narrow Angle Glaucoma

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

Because of the rapid, potentially devastating results of narrow angle glaucoma, you should seek medical treatment immediately if you experience any of the above symptoms.

Gonioscopy is used to determine whether the angle where the iris meets the cornea is open or closed, a key difference between open angle glaucoma and narrow angle glaucoma.

Treatment for Narrow Angle Glaucoma

Medical management to lower the intraocular pressure followed by laser iridotomy is a common treatment for narrow angle glaucoma. During the 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 I controlling eye pressure. During the microscopic procedure, a new drainage channel is created to allow fluid to drain from the eye.