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Las Vegas, NV 89128
To understand our discussions about glaucoma you need to gain an understanding of the anatomy of the eye. The eye is an amazing optical device. The eye focuses the light from the environment, creating an image that is processed and sent to the brain where the image is interpreted. In this way, the eye is very similar to a camera.
The eye is a fluid-filled globe about an inch in diameter. To focus light, the eye needs to maintain a smooth round shape. To keep the eye round, the eye is filled with a fluid called the aqueous, much like the tires on your car are filled with air to keep them round. There is a certain pressure in this aqueous fluid just like your car tire has pressure in the air. Under normal circumstances, the pressure in the eye is between 10 and 20. The fluid is created by a special tissue called the ciliary body. It then circulates through the eye and eventually drains out of the eye at the drainage tissue called the trabecular meshwork.
A visual image is formed when light enters the eye and is focused onto the retina by the clear lens. The retina then changes the image into electrical signals that are sent along one million tiny nerve fibers in the optic nerve. These electrical signals arrive in a special area of the brain where the electrical signals are interpreted.
So how do fluid flow and electrical signals relate to glaucoma? Glaucoma is a disease where the optic nerve and the tiny nerve fibers within it degenerate. A damaged nerve leads to decreased vision and even blindness in advanced cases. The most common cause of the nerve damage (glaucoma damage) is an increased eye pressure. The eye pressure increases when the drain inside the eye (trabecular meshwork) gets clogged and the fluid doesn’t flow through it easily. When the pressure increases, this pushes against the nerve and over many months and years causes the nerve to degenerate.
Early or mild glaucoma has no symptoms which makes it impossible determine a glaucoma diagnosis without a doctor. The eye is an amazing optical device, and the whole visual system, including both eyes and the brain, is even more remarkable. When glaucoma damage starts to injure the small optic nerve fibers, very small areas of the vision are affected. These small areas tend to be in the peripheral vision, so they are not very noticeable. There are other reasons that early glaucoma damage has no symptoms. One is that glaucoma damage happens very slowly, and it isn’t easy to notice if your vision fades away very slowly. The other reason that often there are no symptoms with early glaucoma is that we are lucky to have two eyes that see the same things – the visual areas each eye sees overlap. Even if one eye loses 50% of its vision, the overall vision won’t change if the other eye is healthy.
Because glaucoma has no symptoms, the only way that you can be correctly diagnosed with glaucoma is with a thorough eye exam by an optometrist or ophthalmologist. This is why it is recommended that people at risk for glaucoma get an eye exam at least yearly. If you wait until you have symptoms before you come in for your eye exam, it will be too late and severe irreversible glaucoma damage may have already developed.
Correctly diagnosing glaucoma takes a little detective work by your eye doctor. One clue that glaucoma may be developing is an increased eye pressure. Just like your medical doctor takes your pulse and blood pressure at each visit, your eye doctor measures your eye pressure to look for glaucoma. Some people develop glaucoma even with a normal eye pressure, but usually an elevated eye pressure is what causes the nerve damage. A normal eye pressure is 20 or less. Many people with glaucoma have eye pressures between 22 and 30.
Since the eye pressure is measured indirectly, by gently pushing against the cornea, a thick or thin cornea can lead to incorrect eye pressure readings. Corneal Pachymetry is a test that measures the thickness of the cornea and allows your doctor to verify the accuracy of your eye pressure readings. If the cornea is thicker than normal, a few points can be subtracted from the reading. If the cornea is thinner than normal a few points will need to be added to the eye pressure.
The next clue used to diagnose glaucoma is the appearance of the optic nerve. When glaucoma causes damage to the nerve there are characteristic changes to the nerve appearance. A healthy nerve looks like a small orange circle inside the back of the eye. The nerve looks a little like a donut with a small depression in the middle like a donut hole. When nerve damage develops the donut hole enlarges. This is also referred to as increased “cupping”. During an eye exam your doctor will look at the nerve to see if there are any signs of nerve damage developing. This is easiest to do when the pupil is dilated. Early damage may be a little tricky to identify as there is a lot of variability in the appearance of normal nerves from different individuals. In this case a doctor may miss the nerve damage if he isn’t paying close attention during the eye exam.
The last clues that an eye doctor may use to help to diagnose glaucoma are tests that are done in the office. One of these tests is the visual field test. With this test, small lights or patterns are flashed in areas of the peripheral vision. When the patient sees the light, they respond by pushing a button to tell the computer that the light was seen. Some lights are dim and others are bright. By flashing many lights, the vision is mapped. This map can then be compared to a “normal” group of patients. If glaucoma damage has started to develop, the visual field map will appear abnormal. The visual field test usually takes about 5 minutes for each eye.
The other type of test done to detect glaucoma is a measure of the structure of the nerve and nerve fibers inside the eye. There are one million nerve fibers that travel within the optic nerve. When the nerve reaches the eye these nerves enter the back of the eye and then spread out covering the inside of the eye like a smooth thin carpet. If glaucoma damage develops, the “carpet” of nerve layers inside the eye will change. A thinner carpet is a sign of glaucoma developing, especially if the thinning carpet occurs in certain areas of the retina. The OCT and GDx tests measure the nerve layers inside of the eye and compare the thickness to a group of normal eyes. If your scan shows thinning compared to a normal group there is a high likelihood that glaucoma is developing.
In summary, as part of a thorough yearly eye exam your eye doctor will do some detective work to see if there are signs of glaucoma developing. By measuring the eye pressure, looking carefully at your optic nerve, and doing glaucoma tests, your doctor can determine if glaucoma damage is developing. Since glaucoma has no symptoms an eye exam needs to be done at least yearly.
All modern methods for treating glaucoma are designed to lower the eye pressure. This can be accomplished with medications, lasers, and surgery. To treat glaucoma and lower the pressure in the eye, you can either decrease the amount of fluid going into the eye or open the drain to help fluid leave the eye more easily.
Glaucoma medications are medicated eye drops or gels that are dropped onto the surface of the eye one or more times each day. The medicine is then absorbed into the eye where it interacts with the structures inside the eye. Eye medications either decrease the production of eye fluid (aqueous) or help clean out the drainage system so it works better. Once started, medications are usually used for many years, and sometimes for the remainder of your life. To be effective, medications must be used every day. A common reason patients go blind from glaucoma is a failure to use the medications on a daily basis. Most glaucoma medications only work for 6-12 hours, so regular dosing is important for them to be effective. If doses are missed, the eye pressure will begin to increase within just a few hours. If you take medications, it is important that you pay attention to how much is in the bottle so that you can get refills at the pharmacy regularly. Try to get to the pharmacy BEFORE the medicine runs out so that you don’t miss any days of treatment. Never stop using a medication without first calling your doctor and discussing with them the problems you are having (side effects, cost, etc.).
To avoid confusion, it is very helpful if you know the exact names of your medications and take the bottles with you when you come in for an eye pressure check at the eye doctor’s office.
Because some of these drops are expensive, it is good to not waste drops. Helpful ways to get your drops in easily include having a friend or family member put the drops in for you or lying down on the couch or sofa when putting in the drops. To help the medication absorb into the eye, close your eyes for a few minutes after putting the eye drop in. Some doctors recommend gently squeezing the small eyelid drains by the nose for a few minutes after putting the drops in the eye. This is probably no more helpful than closing your eyelids, so we don’t recommend this.
Although glaucoma medications are generally very safe and well tolerated, there are some possible side effects. All topical eye drops can cause an allergic reaction with redness and itching or eye irritation with burning and a scratchy sensation. Timolol and other Beta-blockers can worsen breathing problems if you have asthma, bronchitis, or COPD. They can also lower the heart rate and cause other heart issues. If you experience any side effects with any medication, you should contact your eye doctor immediately.
At one of your initial visits after glaucoma treatments have been initiated your doctor will choose a target pressure as a goal pressure for your eyes. This target eye pressure is your doctor’s best guess as to a “safe” pressure so no further glaucoma nerve damage develops. The number will depend on how high the eye pressure was before treatment, how much damage has developed, and your age and medical conditions. It is beneficial for you to understand the concept of a target pressure and know the target pressure your doctor has chosen for your eyes. If you don’t know your target pressure, ask your doctor at your next visit.
|Common Target Pressures|
Laser treatments in glaucoma are high technology treatments that are safe and effective at lowering the eye pressure. The most common laser treatment for pressure lowering is the SLT (Selective Laser Trabeculoplasty). During this 5 minute treatment, an intense green light is directed at the eye drain (trabecular meshwork). This bright light causes microscopic damage to the drain. The eye then heals the small damage, during which time the drain gets cleaner and starts to work better, which lowers the eye pressure. The laser is effective in most cases (85% or so) and is generally safe. Some patients have minor light sensitivity and pain for a few days after. Some patients experience an increase in eye pressure. In many cases, eye drops can be avoided or discontinued if the laser is successful.
There are a few other laser procedures done in the treatment of various types of glaucoma. A laser peripheral iridotomy (LPI) makes a small hole in the iris. This laser is done to treat a condition known as a narrow-angle which is a risk factor for developing a type of glaucoma known as angle closure. Cyclophotocoagulation (CPC or ECP) is a laser treatment to the ciliary body, the area of the eye that makes the aqueous fluid. If the pressure is high, the CPC laser damages the fluid-producing cells and decreases the amount of fluid entering the eye.
Glaucoma surgeries help create a new way for fluid to drain away from the eye. This helps to lower the eye pressure. Glaucoma surgeries are outpatient surgeries done in an ambulatory surgery center. This means you do not have to stay in a hospital after surgery. Glaucoma surgeries are generally safe, but rare severe side effects such as infection or bleeding can develop. Glaucoma surgeries are usually done when medications or lasers are not effective or not tolerated because of side effects. There are two main types of surgery, a trabeculectomy, and a glaucoma tube implant.
Trabeculectomy makes a small trap door in the wall of the eye that acts like a pressure release valve to help fluid leave the eye. As fluid leaves the eye, the eye pressure decreases. The final eye pressure depends on how much scar tissue develops after the surgery. If a lot of scar tissue develops the eye pressure can increase and the surgery can fail.
Glaucoma tube implant
With this surgery, a small soft silicone tube is implanted in the eye as a new drain to help lower the eye pressure. It is also a relatively safe procedure. The fluid passes out of the eye through the new drainage tube. There are a few different versions of this surgery; the main tubes are either a Baerveldt or an Ahmed.
Other surgical procedures
There are numerous other surgeries in development or in use to treat glaucoma. They are generally designed to help fluid leave the eye and are related to the surgeries mentioned above. Other surgeries include canaloplasty, deep sclerectomy, express implant, and the trabectome. Unfortunately, no surgery stands out as the best option, and the eye pressure can remain high even after a glaucoma surgery.
Life can be challenging! People can lose their jobs, lose their insurance, run low on money and then have trouble buying expensive medications or paying for doctor visits. Dr. DeBry wants you to know that he will never let financial concerns interfere with his ability to care for your eyes. It would be a shame to suffer permanent vision loss or even blindness because of financial difficulties. Dr. DeBry can help arrange free care and free medications for patients who qualify for financial hardship. If you have financial difficulties which are interfering with your ability to take care of your glaucoma, please communicate this to Dr. DeBry or his staff. We will work to help overcome these issues and keep your eyes healthy and strong. Remember, glaucoma damage is permanent, so staying on top of your treatment even during difficult times is important.
Glaucoma is generally a disease that develops with age. The small drainage pathways (trabecular meshwork) work less efficiently with age. This causes the eye pressure to increase. Many patients are diagnosed with glaucoma in their 70’s and 80’s. Since glaucoma has no symptoms, it is very important that any person 65 or older have a full eye exam at least yearly. The other main risk factor for getting glaucoma is a family history. If you have a parent or sibling with glaucoma, your risk of getting glaucoma is much higher. People with a parent or sibling with glaucoma should get their eyes checked every year starting at age 40, sooner if there is blindness in any relative. If you have glaucoma, please talk with your children and siblings and make sure they are getting their eyes checked regularly. Remember, the main reason people go blind from glaucoma is that the disease is not diagnosed on time.
As a glaucoma specialist in Las Vegas, Dr. Peter DeBry often sees patients who are seeking a second opinion after receiving a diagnosis of a narrow angle. A narrow angle is a common condition related to the size and shape of the eye, and is a risk factor for developing an increased eye pressure. To review eye anatomy – there is a fluid called the aqueous that circulated within the eye. This aqueous is produced by the ciliary body, circulates within the eye, then drains away through the trabecular meshwork. The trabecular meshwork is located near the outer edge of the iris. This small space called the “Angle” has an upper boundary of the cornea (clear window of the eye) and a lower boundary of the iris (colored part of the eye), with these structures coming together like the sides of a triangle. There is usually plenty of space for the fluid to pass next to the iris and out through the trabecular meshwork.
In some people the eye is shaped differently and the drainage area is very narrow. Under certain circumstances, such as dim illumination or stressful situations, the drain can completely close off. When this occurs the fluid continues to be produced and the pressure inside the eye increases over minutes to hours. This is considered an attack of angle closure glaucoma.
This is a very difficult question to answer and depends somewhat on how narrow your angles are. The majority of people with a narrow angle will not develop angle closure. However, it is impossible to predict who will and who will not get glaucoma. Therefore treatment is recommended for all individuals who are determined to have narrow angles.
Patients with mildly narrow angles need no treatment and should have a detailed eye exam yearly. In patients with moderate to severe narrowing, to lower the risk of acute angle closure glaucoma a small hole is placed in the iris with a laser (laser iridotomy). This laser procedure is done in the office or laser center, takes only 2-3 minutes to complete, and has some pain involved. By placing a hole in the iris an alternate pathway is made for the fluid to reach the drainage area of the eye. This prevents complete closure of the angle and the resulting high eye pressure.
Laser surgery is the best treatment for narrow angles. If for some reason you do not want the laser there are two options. The first option is no treatment. Without treatment you will still have the small risk of angle closure glaucoma. This risk will slowly increase from year to year as the angle becomes narrower as you age. The second option is to use an eye-drop (pilocarpine) to lower the risk. The eye drop needs to be used 3-4 times daily, and may make the vision dim or blurry. It will reduce the risk of angle closure, but can’t completely prevent it.
Yes, but generally they are minimal. In most people there is a small elevation in the eye pressure and some inflammation inside the eye. These problems are easily treated with medications. You will be given some drops before the laser and some after to prevent the pressure increase. You will also be given eye drops (Prednisolone) to use for 7 days after the laser to help with the healing process. One out of every 100 people will have a significant increase in eye pressure. Usually this is treated with additional medications, but in extremely rare instances emergency surgery may be needed.
In most cases you will not be aware of any differences in your vision. Approximately 1-in-100 people will report a faint line or crescent of light in their vision. This is caused by stray light coming in through the new opening in the iris. Most people report that the symptoms get less noticeable over time, but if they persist there are several techniques that may improve the visual changes. If your eye has had other problems in the past such as chronic inflammation, cataracts, or corneal swelling, the laser may cause short-term increases in inflammation or corneal swelling. This may make the vision worse for days-to-weeks after the laser. In most cases the vision improves with the use of medications. It is extremely rare for a laser iridotomy to cause visual loss.
After arrival your eye pressure will be checked. Dr. DeBry will review the procedure with you and answer any question that you may have. You will need to sign a consent form before the procedure. You will be given several drops to prepare the eye for the laser. The laser surgery takes 2-3 minutes. You will feel a slight burning and/or snapping sensation. Most people describe this as uncomfortable rather than painful. When the laser is complete you will be given additional drops to prevent the pressure from increasing. You will then need to wait for 30 minutes for a pressure check. If the pressure is fine you will be able to leave. The vision may be dark and blurry for 2-3 hours after the surgery because of the bright lights and lenses used. Because of this we recommend that you have someone with you to drive you home. This is especially true if you have poor vision in your eye that did not have the laser. Please check with Dr. DeBry if you are unable to arrange for a driver. A follow-up appointment will be arranged for 4 weeks after the laser.
After any eye surgery there are certain signs and symptoms to look for. If you experience significant redness, light sensitivity, blurred vision, headache, halos around lights, or nausea you should contact the office immediately. This could be from increased inflammation or high pressure in the eye.