Glaucoma Basics

• Open Angle Glaucoma
• Testing
• Diagnosis
• Treatment
• Helping Yourself

Introduction

This monograph is intended to be your introduction to the basic concepts of open-angle glaucoma and its therapy. It is intended to increase your basic knowledge, allowing you ask more questions that are specifically related to your type of glaucoma and where you are in the progression of the disease.

Medicine is an art and not a science. Although the treatment of glaucoma is based on many years of scientific investigations and upon a large volume of research, the treatment of glaucoma involves a great amount of diagnostic skill. It is difficult, for both the physician and patient, to treat a disease that has no symptoms until it produces blindness. Therapies for glaucoma involve long-term goals. These goals involve preserving the most amount of vision possible. A patient should realize, from the beginning, that it is impossible to return any vision lost from glaucoma before he begins therapy. However, a patient most likely can keep most of vision he currently has.

Communication between the doctor and patient is paramount in the treatment of glaucoma. One of the best ways of combating blindness may be for you and Dr. Robin to work together as a team. Dr. Robin believes that it is important for you to know as much about glaucoma as possible, so that you can ask the questions that are important to you. In fact, Dr. Robin welcomes your asking these questions. He feels that the more you know, the more likely you are to be a better patient and comply with your therapy. The more you comply with your therapy, the better you are able to preserve your vision.

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Open Angle Glaucoma

Glaucoma is the name given to many different diseases. Open-angle glaucoma is one of many forms of glaucoma. Open-angle glaucoma, unlike other diseases, usually has no symptoms. Most forms of open-angle glaucoma have an eye pressure which is too high for an individual's eye. Glaucoma causes vision loss and blindness if left untreated. The visual loss begins in the side vision and is not noticed. It progresses slowly, so that it is usually impossible to detect changes in side vision until they are large and dangerous. Our goal is to treat the eye pressure in hopes of permanently maintaining your vision similar to the vision that you had when you were first diagnosed.

Glaucoma should NOT BE CONFUSED WITH either cataract or macular degeneration. All three diseases are more common in elderly populations. The blindness caused by cataract can be reversed with surgery. It is uncommon to be regain vision lost from macular degeneration.
 
Understanding Eye Pressure

The eyeball like a basketball or a tire, and in this way it has a pressure. Fluid (called aqueous humor) is made inside the back portion of the eye called the "ciliary body". This fluid nourishes the eye. It slowly travels from the back part of the eye to the front of the eye to an area called "the angle" or "trabecular meshwork", where it then exits the eye. This fluid is not tears (as tears are both made and located outside of your eye). But aqueous humor is actually created inside your eye. Therefore, if your eye feels dry, or if your eye tears, this is not related to your aqueous humor or your eye's pressure.

Elevations of your eye's pressure are never caused by too much fluid being made. These elevations in your eye's pressure are caused by blockage to the drainage area of your eye (the angle or trabecular meshwork).
 
Glaucoma if left untreated can cause blindness.Lowering the pressure in the eye, either by using eye drops, laser surgery, or actual incisional surgery can prevent the progression of glaucoma, thus sparing vision. Here Doctor Robin is painlessly measuring the eye’s pressure in less than a minute.
 
If Dr. Robin determines that the pressure in your eye should be lowered, he will first determine what an appropriate goal, or target pressure should be. Following that he will use therapies that do one of the following:

Decrease the amount of fluid which is made. (This is similar to turning off a faucet of a sink which may be overflowing).
Increasing the amount of fluid which the drainage system allows to leave the eye (this is similar to using Liquid Plumber©).
There is currently a great amount of interest in developing medications which protect the integrity of the optic nerve. These medications "strengthen" nerves. These are pharmaceuticals still many years away in the therapy of glaucoma.
Fluid continues to be made even if the drainage system is blocked. This increased amount of fluid in a confined space raises the pressure (this is similar to putting too much air within a tire -- eyes, unlike tires, don't burst if too much air is added).

The pressure always changes and can vary quite a bit, especially in glaucoma patients. This is neither abnormal nor surprising. One can imagine that the "thermostat" within the eye which sets and regulates the eye's pressure does not work as well in eyes with glaucoma. A single pressure reading can be deceiving or misleading. Dr. Robin might therefore place more emphasis on evaluations of the optic nerve appearance and how the eye functions when performing a visual field than one specific eye pressure reading.

There is no known relationship between eye pressure and stress or tension. Eye pressure is not related to caffeine use. Eye pressure and blood pressure are NOT related. The only exceptions to this are as follows:

In younger individuals, it may be less likely for a person to have both glaucoma and high blood pressure.
However, in older individuals, it may be more likely for people to have both high blood pressure and glaucoma.
Some medications which lower your blood pressure may also lower your eye pressure.
To measure eye pressure, an eye drop, which might sting for a few seconds, is placed on your eye. This numbs your eye. A probe is next placed on your eye which measures the pressure inside of it. The pressure inside your eye is related to how much force is needed to indent your cornea just a little bit. This process does not hurt and only takes a matter of seconds!

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TESTING FOR GLAUCOMA

The optic nerve is the part of the eye which is most affected in glaucoma. The optic nerve is not a "single" nerve, but a collection of approximately 1,000,0000 (one million) nerve fibers. Normally, every human looses 5,000 fibers a year through normal aging. It is the only living nerve in the human body which can be seen without making an incision. The optic nerve is similar in many ways to the film in a camera. The optic nerve is the structure that sees images and tells the brain what the eyes are seeing. When glaucoma injures these nerve fibers, eventually killing some of them, it causes loss of vision. When Dr. Robin detects nerve damage, this early damage is the first stage of glaucoma. Damage to the optic nerve is permanent and can not be reversed. Some doctors believe that the more damage that has already occurred, the easier it is for further damage to develop. Once the optic nerve is totally destroyed, an eye can not detect light.

The optic nerve is located in the back of the eye, behind the pupil. Normally if one shines a light on the pupil, the pupil constricts. This makes it extremely difficult if not impossible to adequately examine the optic nerve's structure. Dr. Robin therefore needs to put dilating drops in the eye. These drops temporarily stretch the pupil's muscles so that the pupil, or the window to the back of the optic nerve, will stay open while examining the nerve. These drops usually last a matter of hours. They not only make things seem brighter, but can also cause images to seem blurrier.

Dr. Robin needs to examine both the way the optic nerve looks and the way it functions. This helps him decide whether there is glaucoma, the degree of damage, and whether there has been any progression or change in the amount of damage. Dr. Robin will either sketch the appearance of your optic nerve or take photographs of it. These are NOT X-Rays, but slides which are sent to a film processor to develop. Despite how bright the lights appears, there is no risk from the process of taking photographs of the optic nerve.

Dr. Robin measures the function of your optic nerve by having you perform a visual field test. This test measures your side vision. This is important because the area of visual loss begins in the side vision and is not noticed by patients until glaucoma becomes very advanced. Dr. Robin hopes to stop the damage before it gets that advanced, or if you already have advanced damage, he hopes to prevent it from worsening.

Nobody likes visual field testing. It requires a great deal of concentration. The test is designed to detect the dimmest light that you can see. You will only see one-half of the objects presented by the machine. This can be frustrating and frightening. It is also a boring test. Remember, if you are having trouble with the testing, or are tired, ask the technician to stop and explain the test to you again, or give you a rest!

If glaucoma worsens, visual field defects get larger and leave a patient with a "central island of vision" before blinding them. This can be very dangerous, as it is like looking out of a periscope, not being able to see things to your side. It can cause a person to bump into objects or stumble and fall.

Under proper management and good patient cooperation, it is very unlikely for a patient to go blind from glaucoma. Careful follow-up and good patient compliance severely limit the risk of marked visual loss.

Why Would Contact Lenses Be Used?
After your eye is numbed, Dr. Robin will often place a contact lens on your eye to both look around corners to help see things that normally could not be seen. This is not the same type of contact lens which helps you see, but it helps Dr. Robin see into your eye. It does NOT permanently stay on your eye. This type of contact lens helps determine whether, or not, you have open-angle glaucoma. It is very important to make sure that the correct diagnosis is made. Contact lenses are also used to get a more magnified view of the optic nerve and other structures in the back of your eye. These contact lenses only stay next to your eye for a matter of a minute or so. You probably won't even know when it is placed on, or removed from, your eye.

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DIAGNOSING GLAUCOMA

Glaucoma is truly present only if there is damage noted in the optic nerve or visual field. The actual level of pressure usually does not make as much difference as does the appearance and function of the optic nerve. However, the risk of glaucoma can greatly increase if your pressure gets extremely high. In these situations, Dr. Robin might treat your eye to lower the pressure, despite the fact that there might still not be any damage present. He may feel that your risk of developing glaucoma and loosing vision is worse than the risk of taking medications.

Are There Any Risk Factors That Help Predict Who Gets Glaucoma?
We do not know why specific individuals get glaucoma. We do know the following:

• Nearly 2 million Americans have glaucoma.
• 5% of people over 65 years may have glaucoma.
• It is unusual for patients with glaucoma who are caught early, who regularly take their medications, and who are followed regularly, to go blind.
• Glaucoma can happen at any age, but is more common in elderly individuals.
• Glaucoma happens with equal frequency in both men and women.
• A patient with glaucoma has done nothing to cause the glaucoma.
• Glaucoma can run in families. If your parents or other family members have glaucoma, you should tell this to your eye doctor and you possibly should be examined more frequently, depending upon your age.
• Glaucoma is not a contagious disease.
• Glaucoma is not related to diet, caffeine, or eating habits.
• Glaucoma can occur in an eye which has had a severe injury.
• Glaucoma is more frequent if there is severe inflammation within the eye.
• Glaucoma is over four times more likely in African-Americans. These individuals also seem to develop glaucoma at younger ages.
• Glaucoma is a leading cause of asymptomatic preventable blindness.
• As people grow older, both cataract and glaucoma occur more frequently.
• People with macular degeneration can also have glaucoma.
• It is encouraging to know that once glaucoma is discovered, therapy is usually successful in minimizing any further visual loss. It is therefore almost "good news" to learn that you have glaucoma because it means that it is likely that we can preserve your current level of visual function.
• The quality of most people's lives, outside of taking medications, does not change after they learn they have glaucoma. It is Dr. Robin's goal to help maintain your lifestyle as close to the way it was before you learned you had glaucoma.
• Alcohol does not raise your eye's pressure. However, alcohol is potentially a "dangerous drug" and should be used only in moderation.
• Marijuana does lower your eye pressure. However, our goal is to treat your eye with minimal effects on the rest of your body. Marijuana does the exact opposite. Many people have tried to synthesize marijuana eye drops, but it does not work well for many reasons. There is no legal way to obtain marijuana for glaucoma. It should not be used.

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TREATING GLAUCOMA

• Everything in life has risks! Dr. Robin would only treat glaucoma if he believes that the risks of not being treated and going blind are greater than the risks of any therapy. All choices have risks. Dr. Robin has to take into account at least the following when deciding upon the appropriate course of action:
   
• How advanced the glaucoma is in each eye
• Family history of eye problems
• Other eye problems excluding glaucoma
• Life expectancy
• Life style
• Visual needs
• Medical history
• Medications for other diseases
• Allergies to medications
• The degree of damage from glaucoma
• The rate at which the glaucoma has progressed or is progressing
• The degree of damage caused by glaucoma which is already present in the eye before the beginning of thereapy

Dr. Robin will then decide what is the best course of action. He will discuss the alternatives with you as he feels strongly that any decision is a team decision, between both you, your family, and Dr. Robin. He will discuss the appropriate options, both the positive and negative aspects of each. He takes all options seriously, feeling that there are risks and benefits to all venues of therapy.

Choices for Therapy
Your initial choice of therapy will most likely be between medical (eye drop) and laser therapy. By choosing one, you have not "burned your bridge before you crossed it". That is, you may still choose the other therapy later without a decreased chance of the second therapy working. It is important that you understand both types of therapy so that you can make the best decision for yourself. I will go on and explain both types of therapy.

How Serious Are Eye Drops For Glaucoma?
Eye drops for glaucoma should be taken seriously. They are not just Aspecial water@, but are actually similar to pills (medications) used to treat other general body conditions. Do Not overuse eye drops in an attempt to get an "added effect" as this could be hazardous.

How Can You Minimize the Side Effects of Eye Drops?
There are two tricks which may help you keep much of the eye drop's effect within your eye and not in the rest of your body? The object of both of these tricks is to maximize the amount of time an eye drop stays in contact with your eye and minimize the amount of drop which goes down into your tear duct which then becomes absorbed by your blood stream.

The first is the easiest. It is called "Forced Eye Lid Closure". It means that you should tightly close your eye, after instilling the drop, for approximately five minutes after each eye drop. The second is called "Nasal Lacrimal Occlusion". This requires the placing one of the fingers of your hand upon the side of your eye lid, near your nose. This is where the punctum is located (the area of your eye lid which lets tears drain into your nose). You can use your finger to "close this area off" so that the amount of the drop which gets into you general circulation is minimal. Please ask Dr. Robin to show you a video on how to do this or ask for specific instructions.

Is It Important to Remember to Always Use Your Eye Drops?
Compliance, or strict adherence with therapy, is one important reason why people do not lose vision while on therapy! Do not forget to use your eye drops. Eye drops only last a number of hours (ranging from 6 to 24). If you don't use your eye drop regularly, you are only hurting yourself. Every time you miss an eye drop, there is a time when your eye pressure may be rising again. If you are to take any eye drop three times daily, and you regularly miss one of the three drops, over the course of a year, you might be missing one third of the eye drops you need. This is equivalent to missing eye drops for four months every year!

Almost all medical therapies for glaucoma are eye drops. Most eye drops may sting or burn when placed in the eye. This does not mean that they are working or that they are bad for you. It just means that some people may find a specific eye drop more comfortable than others.

Eye drops are sometimes hard to put in the eye. It is okay to have a friend or family member help you instill an eye drop. It does not matter which part of the eye that the eye drop touches, as long as it gets onto the eye (being on the eye lid is NOT enough)! Sometimes people find eye drops so comfortable that they don't actually know if the eye drop has touched their eye or not. If you are having trouble with this, you may decide to put the drop in your refrigerator. Drops do not require refrigeration, but it may be easier to determine whether a cold eye drop has actually touched your eye or not compared to an eye drop which is at room temperature.

People often worry about how many eye drops to put into their eyes. All you need is one. The space between your lower lid and eye ball usually only holds one-half of an eye drop, so that it is normal for some part of an eye drop to roll down your cheek.

Glaucoma usually involves both eyes. However, Dr. Robin may only start treatment with a drop in only one eye. This does not mean that you may need drops in only one eye. However, it is a way of seeing whether a specific drop works well for you. If the pressure in the eye receiving the drop is much lower than the pressure of the eye on no medication, it lets Dr. Robin know that this medication is actually working. He will then start you on the medication is both eyes, only after he is sure that there has been a successful effect from the drop in the one treated eye.

You have at least a 50% chance of needing more than one type of eye drop to adequately lower your eye pressure. Different classes of eye drops have additive effects to other classes of eye drops. Some individuals take up to five different types of eye drops at the same time to adequately lower the eye pressure. If you require more than one type of drop, either eye drop can be used first. You should wait at least 5 minutes between each drop to insure that you do not wash out the first drop when you instill the second drop. If you think that you are having any side effects from a medication, please mention this to Dr. Robin.

What Types of Eye Drops are Available for Therapy?
There are currently five different types of eye drops available for the therapy of glaucoma. A sixth drug will soon be available.

Beta-blockers (betaxolol, timolol, optipranolol, carteolol) (usually yellow or blue topes) are usually the first type of drug used. They lower eye pressure by decreasing the amount of fluid made by the ciliary body within your eye. They are either used once or twice daily. They can lower your eye pressure about 20% to 25% on the average. Complications associated with these medications are rare if used correctly, but should be understood so that you do not take a medication which is not appropriate for you. They should not be used in the following patients: those who have asthma, severe heart failure, significant blockage of their carotid arteries, an especially slow pulse, severe lung or heart disease, or are prone to depression. Additionally, in males with a history of sexual dysfunction, you might want to ask Dr. Robin about the advisability of this class of medications.

There are two different types of beta-blockers. There are selective beta blockers (Betoptic©) which are not quite as strong in lowering your eye pressure, but are safer in that they have less effect on your pulse rate, heart, and lungs. Non-selective beta blockers lower your eye pressure slightly more than do selective blockers. They may also make an individual's blood lipids (fats in the blood stream which can predispose one to heart disease) change in such a way as to increase your risk of heart attack or stroke.

Miotics (pilocarpine, carbachol, phospholine iodide, pilopine ointment, ocuserts©) (usually green tops) are the oldest class of medications which we use for glaucoma. They work by increasing the amount of fluid which leaves the eye and are given at various dosing intervals varying between once weekly to four times daily. We have used this class of medication for over a century. Some of them (pilocarpine) are actually occurring naturally. They are extremely safe for your body if used as an eye drop or ointment. Most side effects are limited to the eye. All side effects are temporary and are reversible when the medication is stopped. They make your pupil smaller which can make your vision seem dimmer. They can also cause your vision to seem blurry or cause a headache.

Alpha-agonists (Iopidine©) (white tops) are used with twice or three times daily. Eye pressure is lowered by decreasing the amount of aqueous humor produced. It usually takes a month to determine how well this type of medication works to lower your eye pressure. It is quite unusual to have systemic complications when this medication is used. However, it is not unusual for your eyes or eye lids to become red and swollen. (This will stop and go back to normal if the eye drop is stopped). Infrequently, you may develop a dry sensation in your mouth or nose.

Epinephrine (dipivefrin, epinephrine HCL, epinephrine borate) is similar to a naturally occurring chemical in the bottom. It is usually used twice daily. It does not work as well as beta-blockers so it is usually a second line of therapy or used in patients where beta-blockers can not be used. They have a minimal additive effect if used in addition to a beta-blocker (that is, if using both individual medications together, 5 minutes apart). These medications work by increasing the amount of fluid which leaves the eye. The main complications associated with epinephrine are: a redness of the eye and eye lid associated with itching, an elevation of your blood pressure, and an increase in your pulse rate.

Carbonic Anhydrase Inhibitors (Diamox©, Neptazane©, MZM©, Trusopt©, acetazolamide, methazolamide). (white or orange pill) or Trusopt© (orange top drop bottle) is the only eye drop. The remainder are pills. Dosing varies from twice to four times daily. These all work by decreasing the amount of aqueous humor made. They are all sulfa drugs -- so if you are allergic to SULFA you probably should not take these medications. This class of medication was first used clinically in the 1950's. Trusopt© was introduced in mid-1995. The main disadvantage with the pills is that you are treating the body with a medication and inadvertently some of the medication affects the eye. Only approximately 50% of individuals who take carbonic anhydrase inhibitor pills can tolerate the side effects. These include fatigue, loss of appetite, kidney stones, depression, a funny taste in the mouth. This like all sulfa drugs can cause a type of anemia which is extremely rare and can be fatal in a very very small number of patients. The only thing which should be added about the eye drops Trusopt© is that they also burn in one out of four individuals who take them.

Can You Use a Laser to Treat Glaucoma?
Lasers were first introduced in the therapy of glaucoma in approximately 1978. A laser is a special form of light energy. Laser procedures are done in the office. A numbing drop, similar to the drop used to measure your eye pressure is used to anesthetize your eyes. A special type of contact lens is used to help keep your eye lids parted and aim the laser beam with greater magnification into the trabecular meshwork. Dr. Robin uses a slit lamp (the instrument which he normally uses to examine your eyes) to aim the laser.

The laser treatment is quite safe. It only takes a matter of minutes to do. You will sit at a slit lamp and see a greenish light focussed on your eye. It will only go where directed. Each of 40 to 90 laser spots are aimed at the trabecular meshwork. Each spot lasts less than one second so that you don't have to worry about blinking or moving your eyes. The light is bright, but not painful. You might occasionally feel "a pin-prick" sensation associated with a laser spot.

After the laser procedure, Dr. Robin will take the contact lens off your eye. He will check you eye's pressure again in about 45 minutes to insure that the eye pressure has not gone up instead of down (this happens in only approximately 1% of cases). He will give you a eye drop to decrease inflammation which he would like you to use four times daily for a week. Your vision might be slightly blurry for about an hour. Your eye might scratch or sting or feel like something is in it for about a day or two. Your eye might also be blood shot for approximately three days.

The laser procedure does not take effect for about four to six weeks. The laser works adequately to lower the eye pressure in approximately 80% of people one year later. At five years, the effect continues in 50% of people.

The laser has proven to be extremely safe and effective. Many ophthalmologists feel that it is safer than many types of medications. Laser surgery for glaucoma is being done at an earlier stage of the disease in the last few years. In a National Eye Institute evaluation, laser therapy for glaucoma was compared to medical therapy of glaucoma as the initial treatment. It was found to be both as safe and as effective as medical therapy.

Can Surgery be Performed for Open-Angle Glaucoma?
Over the last few decades surgery for glaucoma has become much safer and effective. It initially was reserved for patients who had failed all other types of therapy. A National Eye Institute study is now comparing surgery to medicine as an initial therapy for glaucoma. Eye surgery for glaucoma involves the creation of a partial thickness hole in the wall of your eye. Special chemicals are often used to keep this hole open as it is the body's natural tendency to close all holes. This hole is like a trap door and acts like a safety valve. Fluid (aqueous humor) now has a new place to escape. A blister (or "bleb") is created under your eye lid. This acts as a reservoir for the fluid.

The surgery, called a trabeculectomy, can be performed on an outpatient basis. You do not require general anesthesia for this. An anesthetist or anesthesiologist will give you medicine to put you into a twilight sleep. During this time, numbing medication will be injected surrounding your eye. This will keep your eye from feeling anything, seeing the surgery, and moving during surgery.

You will wear a patch over your eye only until the following day. Following that, you will need to protect your eye with either a piece of plastic (called a shield) which you will be given, or your glasses.

Your vision will be diminished for three to eight weeks following surgery. Unfortunately, we can not set a thermostat within your eye to achieve an exact pressure. In many cases, the success rate of filtering surgery is over 90%. However, some times the pressure is either below or above our desired goal and further surgery may be required.

Filtration surgery would not be suggested unless it was felt that the risk of now surgery was worse than the risks involved with surgery itself. The main risks associated with filtration surgery for glaucoma are:

Loss of vision through hemhorrage or infection (extremely infrequent)
Infection at any time after surgery (extremely infrequent)
Cataract formation or progression (Infrequent)
Need for further surgery (less than 1 out of 5)
Discomfort (rare)
Most people need no medications following glaucoma surgery. They also usually do not need a change in their spectacle correction.

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HELPING YOURSELF

Here are several things you can do to help yourself:
 

• It is suggested that people who do regular exercise are less likely to develop damage as quickly as those who do not.
• Always take your medications regularly. Never miss your drops or pills. If you forget your medications, take them when you remember. Then go back to your customary schedule.
• Try to arrange your medications around habits which you already might have, such as meal time, brushing your teeth, or going to bed.
• Never miss appointments.
• Ask questions so that you can be well informed.

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