Glaucoma Treatment in Henderson, NV
A leading cause of preventable blindness, 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.
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What is Glaucoma?
A leading cause of preventable blindness.
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.
How Glaucoma Affects The Eye
Each tiny nerve fiber of the optic nerve is responsible for a certain area of vision. Glaucoma damage causes these tiny nerve fibers to degenerate. The loss of a few nerve fibers is completely unnoticeable. This is why mild glaucoma has no symptoms. As more and more nerve fibers are damaged, subtle changes start to develop with certain areas of the vision becoming less clear. Even this is usually so mild that the average person doesn’t notice any changes in their vision. Small changes like this can be detected with a visual field test that measures glaucoma damage in the peripheral vision. With more damage over time you may start to notice trouble seeing things in dim lighting and a general decrease in the quality of the vision. In late stages of the disease severe visual disability and blindness can occur. Glaucoma damage to the nerve fibers is permanent and irreversible. Once areas in the vision are lost they can never be brought back. That is why treatment and close monitoring are so important.
How Glaucoma is Diagnosed
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.
Narrow Angle Glaucoma
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.
Glaucoma Risk Factors
- Family History
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.
What Is A Glaucoma Suspect?
A Glaucoma Suspect is a person who has a nerve that looks abnormal. Glaucoma causes slow damage to the optic nerve, which changes the shape of the nerve where it enters the eye. Your optic nerve may be abnormal appearing because of early glaucoma, because of an old injury, or even because of developmental differences in the size and shape of the eye at birth. Most of the time glaucoma damage is caused by high pressure in the eye, but occasionally there can be damage even with normal pressures.
When your doctor sees an abnormal appearing optic nerve he needs to find out if it is abnormal because of: early glaucoma or from mildly abnormal nerve development. Glaucoma is diagnosed using three pieces of information: the appearance of the optic nerve, the eye pressure, and the results of specialized testing.
Information from each of these three areas; the optic disc, the eye pressure, and specialized testing, helps your doctor to determine if you have glaucoma, and if the glaucoma is getting worse over the years. Several tests should be done early on to serve as a reference upon which all future tests can be compared. These tests will be repeated regularly to look for changes.
What to Monitor after Glaucoma Diagnosis?
Once you have been diagnosed with glaucoma and started treatment, the most important part of your future care is making sure the glaucoma is stable and not getting worse. Most people who use their drops regularly do not lose vision, but glaucoma can get worse. If there are signs of glaucoma advancing, additional treatments may be needed and your target pressure may need to be decreased. There were several clues that your doctor used in making the initial diagnosis of glaucoma. These same clues are monitored to see if glaucoma is getting worse.
Glaucoma Treatment Options
All modern methods for treating glaucoma are designed to lower the eye pressure. This can be accomplished with medications, lasers, and surgery.