Glaucoma is a disease of the optic nerve caused by excess pressure of the aqueous humor inside the eye.
Aqueous humor is the clear, watery fluid inside the eye that keeps it firm and spherical. In a healthy eye, a small amount of aqueous humor is constantly produced while, at the same time, an equal amount leaves the eye through a microscopic drainage system called the drainage angle. Because the eye is a closed structure, if the only exit for the aqueous humor -- the drainage angle – is blocked, the fluid being produced cannot escape and the excess pressure inside the eye can damage the optic nerve fibers, causing blind spots to develop.
This condition can often go unnoticed until there is a great deal of damage to the optic nerve. Left untreated, the entire optic nerve can be destroyed, resulting in total blindness. Early detection and treatment by your ophthalmologist is therefore critical in order to avoid permanent optic nerve damage and blindness.
How is Glaucoma Detected?
The best way to detect glaucoma is with regular eye exams by your ophthalmologist. Four different things are usually tested in a complete and painless glaucoma exam.
- Tonometry -- measure the intraocular pressure (the pressure of the fluid inside the eye)
- Gonioscopy -- inspect the drainage angle of the eye for any blockage
- Ophthalmoscopy -- evaluate any damage of the optic nerve
- Perimetry --test the visual field of the eye
These tests may also need to be repeated on a regular schedule to determine if your damage is improving or worsening with time. Depending upon your individual situation however, some of these tests may not be necessary.
Recommended Intervals for Glaucoma Eye Exams Are As Follows
- Age 20 to 39 -- People with a family history of glaucoma and/or those of African descent, should have a medical exam every 3 to 5 years. Other should be seen at least once during this time period.
- Age 40 to 64 -- Every 2 to 4 years
- Age 65 or older -- Every 1 to 2 years
Who Is At Greatest Risk?
Glaucoma is the leading cause of blindness in the United States , and is most common among the elderly, but increased pressure of the aqueous humor inside the eye does not necessarily mean you have glaucoma.
The most important risk factors for glaucoma include:
- Increased age
- African ancestry
- A family history of glaucoma
- Past injuries to the eye
Your ophthalmologist will consider these factors when determining whether you need treatment for glaucoma, or if you should be closely monitored as a glaucoma suspect. As a glaucoma suspect, your risk of developing glaucoma would be higher than normal, warranting regular exams for early detection of any optic nerve damage.
Different Types of Glaucoma
Chronic open-angle glaucoma – Found in more than 90% of glaucoma patients, this is the most common form of glaucoma in the United States , and occurs as a result of aging. With time, the drainage angle of the eye becomes less efficient, the pressure within the eye gradually increases and optic nerve damage results. Often, patients are unaware they have chronic open-angle glaucoma until nerve damage is quite severe, because it progresses so slowly and painlessly.
Angle-closure glaucoma – This is when the drainage angle of the eye is suddenly and completely blocked, resulting in a rapid buildup of pressure within the eye, and equally rapid damage to the optic nerve.
Symptoms of Angle Closure
- Blurred vision
- Severe eye pain
- Rainbow halos around lights
- Nausea and vomiting
You should call your ophthalmologist immediately if you experience any of these symptoms. Unless treated quickly, angle-closure glaucoma results in complete blindness. It is most common in people of Asian descent, less common in people of European descent, and rare in people of African descent.
In some cases, glaucoma can present characteristics of both chronic open-angle and angle-closure glaucoma. This is usually called chronic angle closure glaucoma or mixed mechanism glaucoma, and is most common in people of African ancestry.
In general, optic nerve damage caused by glaucoma is irreversible. Eye drops, oral medication (pills), laser and other surgical procedures are only used to slow the progression of the disease and lessen any further damage.
Eye Drops & Oral Medication
The most common treatment for glaucoma is the use of eye drops several times a day, often in combination with an oral medication. These treatments reduce pressure within the eye by either improving the flow of fluid through the drainage angle, or by slowing the production of aqueous humor within the eye.
To work, these medications must be taken regularly and continuously. Treatment for glaucoma requires teamwork between doctor and patient in order to be effective. The doctor prescribes the proper treatment, and you make sure to take the medication as prescribed. Never change your medication or stop taking it, without consulting your ophthalmologist.
Glaucoma medication can cause side effects and you should be sure to immediately contact your ophthalmologist if you think you may be experiencing any of the following side effects:
For Eye Drops:
- A stinging sensation in the eyes
- Red eyes
- Changes in pulse and heartbeat
- Changes in energy level
- Changes in breathing (especially if you have asthma or emphysema)
- Blurred vision
For Oral Medications:
- Tingling of fingers and toes
- Loss of appetite
- Bowl irregularities
- Kidney stones
- Anemia or easy bleeding
There are two different types of laser surgeries which can be effective in treating glaucoma – one for open-angle glaucoma, and one for angle-closure glaucoma.
With open-angle glaucoma, the laser is used to modify the drainage angle and help control the pressure of the fluid within the eye. This procedure is called trabeculosplasty.
In angle-closure glaucoma, the laser is used to create a hole in the iris – the part of the eye that gives it its color – to improve the flow of fluid to the drainage angle. This procedure is called iridotomy.
Your ophthalmologist may recommend surgery if eye drops and oral medication appear ineffective, and if they feel it is safer to operate than to allow the optic nerve damage to continue. When operative surgery is necessary, miniature instruments are used to create a new drainage channel for the fluid to leave the eye, thereby helping relieve the excess pressure. Although serious complications due to glaucoma surgery are rare, it is important to remember, that as with any surgery, complications can occur.
Please Remember: Regardless of the recommended course of treatment, frequent exams and testing are critical in preventing vision loss if you have glaucoma. Because damage from glaucoma often progresses slowly and painlessly, without frequent exams, you may be unaware that your condition has changed over time, and that it may require a different course of treatment.
As with any serious disease of the eye, please feel free to contact us if you have any questions about your situation.