About Glaucoma



Glaucoma Evaluation


Because it has no noticeable symptoms, glaucoma is a difficult disease to detect without regular, complete eye exams.

During a glaucoma evaluation, your ophthalmologist will perform the following tests:

•Tonometry. Your ophthalmologist measures the pressure in your eyes (intraocular pressure, or IOP) using a technique called tonometry. Tonometry measures your IOP by determining how your cornea responds when an instrument (or sometimes a puff of air) presses on the surface of your eye. Eyedrops are usually used to numb the surface of your eye for this test.

•Gonioscopy. For this test, your ophthalmologist inspects your eye’s drainage angle—the area where fluid drains out of your eye. During gonioscopy, you sit in a chair facing the microscope used to look inside your eye. You will place your chin on a chin rest and your forehead against a support bar while looking straight ahead. The goniolens is placed lightly on the front of your eye, and a narrow beam of light is directed into your eye while your doctor looks through the slit lamp at the drainage angle. Drops will be used to numb the eye before the test.

•Ophthalmoscopy. With this test, your ophthalmologist can evaluate whether or not there is any optic nerve damage by looking at the back of the eye (called the fundus). There are two types of ophthalmoscopy: direct and indirect. With direct ophthalmoscopy, your ophthalmologist uses a small flashlight-like instrument with several lenses that magnifies up to about 15 times. This type of ophthalmoscopy is most commonly done during a routine physical examination. With indirect ophthalmoscopy, the ophthalmologist wears a headband with a light attached and uses a small handheld lens to look inside your eye. Indirect ophthalmoscopy allows a better view of the fundus, even if your natural lens is clouded by cataracts.

•Visual field test. The peripheral (side) vision of each eye is tested with visual field testing, or perimetry. For this test, you sit at a bowl-shaped instrument called a perimeter. While you stare at the center of the bowl, lights flash. Each time you see a flash, you press a button. A computer records your response to each flash. This test shows if you have any areas of vision loss. Loss of peripheral vision is often an early sign of glaucoma.

•Photography. Sometimes photographs or other computerized images are taken of the optic nerve to inspect the nerve more closely for damage from elevated pressure in the eye.

•Special imaging. Different scanners may be used to better determine the configuration of the optic nerve head or retinal nerve fiber layer.

Each of these evaluation tools is an important way to monitor your vision to help ensure that glaucoma does not rob you of your sight. Some of these tests will not be necessary for everyone. Your ophthalmologist will discuss which tests are best for you. Some tests may need to be repeated on a regular basis to monitor any changes in your vision caused by glaucoma.


Intraocular Pressure


Elevated intraocular pressure (high pressure within the eye) is the number one risk factor for glaucoma. However, elevated intraocular pressure (IOP) does not always cause glaucoma.

The average eye pressure in adults ranges between 10 mm Hg and 21 mm Hg (“mm Hg” stands for “millimeters of mercury”). There can be a significant difference in your IOP throughout the course of a day. This variation is known as diurnal fluctuation. We know that many patients with IOP in the 20s do not develop glaucoma. Up to 50% of patients diagnosed with glaucoma have an initial pressure reading lower than 22 mm Hg. Intraocular pressure is not a very sensitive tool for diagnosing glaucoma, but it becomes very useful in monitoring treatment for glaucoma.

A variety of methods can be used to check the intraocular pressure, but the most common is applanation tonometry. Your ophthalmologist will often set a “target” pressure for you and will work hard to keep the pressure at or below that target to help preserve your vision.


Neovascular Glaucoma


Neovascular glaucoma is a particularly aggressive and difficult to treat kind of glaucoma. It is caused by new, small blood vessels growing in the front part of the eye. These neovascularvessels grow on the surface of the iris (the colored part of the eye) and over the drainage channel, blocking the flow of fluid from the eye. This causes a rapid and painful rise in pressure within the eye. This type of glaucoma often does not respond well to medical treatment, and the high intraocular pressure can lead to a rapid loss of vision.

Causes of neovascular glaucoma include diabetic retinopathy, vein and artery occlusions, carotid artery disease, and many other conditions. The prognosis for neovascular glaucoma is poor. The goal of treatment is to minimize the factors that have caused the neovascularization, usually using a laser treatment called panretinal photocoagulation or anti-VEGF injections.

If the high eye pressure persists, treatment can include medication or surgery. When surgery is recommended, a particular type of medication therapy called antimetabolite therapy improves the chances of success. Because of the risk of scarring, seton surgery is often recommended.

The goal in treating neovascular glaucoma is to lower the intraocular pressure, preserve vision, and maintain a comfortable eye.


Selective Laser Trabeculoplasty


Selective laser trabeculoplasty (SLT) is a laser surgical procedure used to help lower intraocular pressure (IOP) of patients with open-angle glaucoma. SLT is used to treat the eye’s drainage system, known as the trabecular meshwork—the mesh-like drainage canals that surround the iris. Treating this area of the eye’s natural drainage system improves the flow of fluid out of the eye, helping to lower the pressure.

The laser used in SLT works at very low levels. It treats specific cells selectively, leaving untreated portions of the trabecular meshwork intact. For this reason, SLT, unlike other types of laser surgery, may be safely repeated many times.

SLT is typically performed in the ophthalmologist’s office or an outpatient surgery center. The procedure usually takes about five to ten minutes. First, anesthetic drops are placed in your eye. The laser machine looks similar to the examination microscope that your ophthalmologist uses to look at your eyes at each office visit.

You will experience a flash of light with each laser application. Most people are comfortable and do not experience any significant pain during the surgery, although some may feel a little pressure in the eye during the procedure.

Most people will need to have their pressure checked after the laser treatment, since there is a risk of increasing IOP after the procedure. If this does occur, you may require medications to lower the pressure, which will be administered in the office. Rarely, the pressure in the eye increases to a high level and does not come down. If this happens, you may require a surgery in the operating room to lower the pressure.

Most people notice some blurring of their vision after the laser treatment. This typically clears within a few hours. The chance of your vision becoming permanently affected from this laser procedure is very small.

Most patients can resume normal daily activities the day after laser surgery. You may need to use eyedrops after the procedure to help the eye heal properly.

Risks associated with SLT include:

•increased pressure in the eye, possibly requiring medication or surgery;

•inflammation in the eye;

•bleeding;

•damage to the cornea, iris, or retina from the laser light;

•failure to adequately lower the eye pressure; and

  1. need for repeat laser surgery.


It will take several weeks to determine how much SLT will lower your eye pressure. You may require additional laser or glaucoma drainage surgery to lower the pressure if it is not sufficiently lower after the first laser treatment.

Most patients must continue to take medication in order to control and maintain their IOP; however, surgery can lessen the amount of medication needed.

While some people may experience side effects from medications or surgery, the risks associated with these side effects should be balanced against the greater risk of leaving glaucoma untreated and losing your vision. Steroid GlaucomaSteroid or glucocorticoid medications are used to treat a variety of medical conditions. They can be administered by mouth, nasal sprays or inhalers, eyedrops, or injections. No matter how the medication is taken, up to 20% of patients taking steroid medications develop elevated intraocular pressure (IOP).

If eye pressure does become elevated, sometimes the steroid medicine can be stopped or decreased, helping to alleviate the problem. If the steroid medication was given by injection in or around the eye, the eye pressure may be harder to control.

If medical therapy does not adequately lower IOP, surgery may be required. As with other forms of glaucoma, if IOP can be controlled, patients tend to do well.

Visual Field Testing


Because it has no noticeable symptoms, glaucoma is a difficult disease to detect without regular, complete eye exams.

One particular test, called a visual field test (orperimetry test), measures all areas of your eyesight, including your side, or peripheral, vision. A visual field test can help find certain patterns of vision loss and is a key way to check for glaucoma. It is very useful in finding early changes in vision caused by nerve damage from glaucoma.

To take this painless test, you sit at a bowl-shaped instrument called a perimeter. While you stare at the center of the bowl, lights flash. Each time you see a flash you press a button. A computer records the location of each flash and whether you pressed the button when the light flashed in that location. At the end of the test, a printout shows if there are areas of your field of vision where you did not see the flashes of light. This test shows if you have any areas of vision loss. Loss of peripheral vision is often an early sign of glaucoma. Regular perimetry tests are an important technique for learning how, if at all, your vision is changing over time. It can also be used to see if treatment for glaucoma is preventing further vision loss. Argon Laser TrabeculoplastyArgon laser trabeculoplasty (ALT) is a laser surgical procedure used for patients with open-angle glaucoma to help lower intraocular pressure (IOP). ALT is used to treat the trabecular meshwork—the mesh-like drainage canals surrounding the iris—that serves as the eye’s drainage system. The goal of treatment with ALT is to improve the flow of fluid out of the eye, helping to lower IOP.

ALT is typically performed in the ophthalmologist’s office or an outpatient surgery center. The procedure usually takes about five to ten minutes. First, anesthetic drops are placed in your eye. The laser device looks similar to the examination microscope that your ophthalmologist uses to look at your eyes at each office visit.

You will experience a flash of light with each laser application. Most people are comfortable and do not experience any significant pain during the surgery, though some may feel a little pressure in their eye during the laser procedure.

Most patients will need to have their pressure checked after the laser treatment, since there is a risk of increased eye pressure after the procedure. If this does occur, you may require medications to lower the pressure, which will be administered in the office. Rarely, IOP elevates to a very high pressure and does not come down. If this happens, you may need to have surgery to lower the pressure.

Most people notice some blurring of their vision after the laser treatment. This typically clears within a few hours. The chance of your vision becoming permanently affected from this procedure is very small.

In general, patients can resume normal daily activities the day after laser surgery. You may need to use drops after the laser surgery to help the eye heal properly.

Risks associated with ALT include

•increased pressure in the eye, possibly requiring medication or surgery to lower it;

•inflammation in the eye;

•bleeding;

•damage to the cornea, iris, or retina from the laser light;

•failure to adequately lower the eye pressure; and

•need for repeat laser surgery.

It will take several weeks to determine how much your pressure will be lowered with ALT. You may require additional laser or glaucoma drainage surgery to lower the IOP if it is not sufficiently lowered after the first laser treatment.

In most cases, medications are still necessary to control and maintain eye pressure. However, surgery may lessen the amount of medication you need. Beta Blockers for the Treatment of GlaucomaWhile there is no cure for glaucoma, it can be controlled with proper management.

Elevated intraocular pressure (IOP) can damage the optic nerve, which may lead to vision loss. Treatment for glaucoma focuses on lowering the IOP to a level that is less likely to cause further optic nerve damage. This is known as the “target pressure.” The target pressure differs from individual to individual. Your target pressure may change during your course of treatment if the progression of glaucoma is not arrested.

If you have glaucoma, your ophthalmologist may prescribe medication to lower your eye IOP. There are many more choices for topical treatment today than there were only a few years ago. Your ophthalmologist has chosen a beta-blocker medication to treat your glaucoma.


How Do Beta Blockers Work?


Beta-blocker (beta adrenergic antagonist) medications are reliable for lowering intraocular pressure. They work by decreasing the amount of fluid that the eye continually produces, called the aqueous humor. For many years, beta blockers were the mainstay of treatment. Thus, we have a lot of experience with this medication for the treatment of glaucoma.


Types of Beta-Blocker Medications
There are two general classes of beta blockers: nonselective and selective. Nonselective beta blockers have more effects on the body’s beta receptors system-wide and are associated with more side effects. The nonselective beta blockers are also more effective at lowering IOP.

The nonselective beta blockers include

•levobunolol (Betagan, AKBeta);

•carteolol (Ocupress);

•metipranolol (Optipranolol);

•timolol (Timoptic, Betimal, Istalol); and

•timolol gel (Timoptic XE).

Generic versions of timolol and timolol gel are now available. Consult with your ophthalmologist to be sure that a generic product is an acceptable alternative for you.

The only available selective beta-blocker medication is

•betaxolol (Betoptic, Betoptic S).

Betaxolol is the generic form of Betoptic.

While a selective beta-blocker eyedrop has a better safety profile, especially in terms of respiratory symptoms, it still must be used with caution in patients with asthma or emphysema. The eye pressure-lowering effect is slightly less with selective beta blockers. There is only a minimal additive effect in terms of lowering eye pressure in patients already taking oral beta blockers, and there is the risk of further additive side effects. If you are already taking a beta-blocker medication by mouth or if your primary care doctor newly prescribes a beta blocker, please notify your ophthalmologist.


Possible Side Effects of Beta Blockers
All medications, including eyedrops, can have side effects. Some people taking beta-blocker eyedrops may experience

•wheezing or difficulty breathing;

•slow or irregular heart beat or decreased response of heart rate to exercise;

•increased risk for heart failure;

•depression;

•impotence;

•headache, dizziness or weakness;

•in diabetics, difficulty sensing blood glucose changes; and

•eye irritation or allergy.

Medication Tips
For glaucoma medications to work, you must take them regularly and as prescribed by your doctor. With each new medication that your ophthalmologist prescribes, make sure you understand the following:

•the name of the medication;

•how to take it;

•how often to take it;

•how to store it;

•if you can take it with your other medications (make sure all of your doctors know about all the different medications you take, including any nonprescription medications);

•what the possible side effects may be;

•what you should do if you experience side effects; and

•what you should do if you miss a dose.