Glaucoma is an eye disease than can greatly impact your vision, with some patients losing their vision completely. There are many types of glaucoma and they most often occur in adults that are over the age of forty. However, this doesn't mean that young adults, children, and even infants can't get glacoma too.
Each person that is over forty, with a family history of glaucoma, poor vision, diabetes, or is using corticosteroid medications such as Prednisone is at an increased risk of developing glaucoma. In African Americans, glaucoma will often occur at an earlier age and with a greater risk of vision loss.
If you think you may be at risk of developing glaucoma, it's important to know the signs as early as possible, before it gets worse. Let's ta
Diagnosis of glaucoma
In general, the hallmark sign of this condition is a loss of peripheral vision, where a person can see in front of him or herself but has lost the vision to the side. But why does eye pressure rise to cause glaucoma in the first place?
Glaucoma usually occurs when intraocular pressure increases, and this occurs when the fluid pressure in the eye’s anterior chamber (the area between the cornea and the iris) becomes abnormally high. This fluid, called aqueous humor, flows out of the eye through a channel. If this channel becomes blocked, fluid builds up causing glaucoma although the direct cause of this blockage is unknown. However, doctors do know that the condition is commonly inherited.
Less common causes of glaucoma include a blunt or chemical injury to the eye, severe eye infection, blockage of blood vessels in the eye, inflammatory conditions of the eye, and eye surgery to correct another condition. Glaucoma usually occurs in both eyes, but it may also involve each eye to a different extent. An ophthalmologist will test your vision and examine your eyes through dilated pupils, but the doctor will also perform a procedure called tonometry to check for eye pressure.
Glaucoma tests are painless and take very little time so you should not be worried.
What are the types of glaucoma?
There are two main types of glaucoma.
* Open-angle glaucoma or wide-angle glaucoma is the most common type of glaucoma. The structures of the eye appear normal, but fluid in the eye does not flow properly through the drain. This is famous as the trabecular meshwork.
* Angle-closure glaucoma or acute or chronic closed-angle or narrow-angle glaucoma is a less common type of glaucoma, but can cause a sudden buildup of pressure in the eye with poor drainage. This is because the angle between the iris and the cornea, where a drainage channel for the eye is located, is too narrow. On the other hand, the pupil could open too wide, narrowing the angle and blocking the flow of the fluid through that channel.
What are the symptoms of glaucoma?
For most people, there are usually few or no symptoms of glaucoma, but the first sign is often the loss of peripheral or side vision. This can go unnoticed until late in the disease. Detecting glaucoma early is one reason you should have a complete exam with an eye specialist every one to two years because intraocular pressure can rise to severe levels. In these cases, sudden eye pain, headache, blurred vision, or the appearance of halos around lights may occur as the main symptoms. If you have any of these symptoms, seek immediate medical care. You should especially watch for symptoms such as seeing halos around lights, narrowing of vision, vision loss, and redness in the eye, or hazy-looking eyes. If you experience nausea, vomiting, or pain in the eye you should also see the doctor.
How to treat glaucoma
Glaucoma treatment may include prescription eye drops, laser, or even microsurgery.
* Eye drops for glaucoma either reduce the formation of fluid in the front of the eye or increase its outflow. Side effects of glaucoma drops may include allergy, redness of the eyes, brief stinging, or visual blurring. You could also experience irritated eyes. Some glaucoma medications may affect the heart and lungs, so be sure to tell your doctor about any glaucoma medication you are currently taking or are allergic to.
* Laser surgery for glaucoma slightly increases the outflow of the fluid from the eye in open-angle glaucoma. It could also eliminate fluid blockage in angle-closure glaucoma. Types of laser surgery for glaucoma include trabeculoplasty, in which a laser pulls open the trabecular-meshwork drainage area. Another method is iridotomy, in which a tiny hole in the iris allows the fluid to flow more freely. Your doctor could also choose cyclophotocoagulation, in which a laser beam treats areas of the ciliary body, reducing the production of fluid.
* Microsurgery for glaucoma is a procedure where a new channel is created to drain the fluid, thereby reducing intraocular pressure that causes glaucoma. Sometimes this form of glaucoma surgery fails and the doctor must repeat it. Other potential complications of glaucoma microsurgery are a temporary or permanent loss of vision, as well as bleeding or infection.
* The best treatment for open-angle glaucoma is a combination of eye drops, laser trabeculoplasty, and microsurgery. Traditionally in the U.S., medications are the first choice, but there is increasing evidence that some people with glaucoma may respond better with early laser surgery or microsurgery. However, you should talk to your doctor to find out which glaucoma treatment is right for you. Although you cannot prevent glaucoma, if your doctor diagnoses and treats you early, he could be able to control the disease.
Tests for glaucoma
Ophthalmologists use three types of tests to screen for glaucoma in people at risk. These tests also help monitor people during treatment. The three tests are tonometry to measure intraocular pressure, ophthalmoscopy to inspect the optic nerve, and perimetry to test the visual fields. A high IOP warrants further testing, and the final diagnosis is made by also finding evidence of optic nerve damage. The doctor could also diagnose you by identifying defects in the visual fields characteristic of glaucoma.
* Tonometry measures intraocular pressure or IOP, by assessing the amount of force necessary to make a slight indentation in a small area of the cornea. The most effective way to do this is with applanation tonometry, where anesthetic eye-drops are going into numb the eye. Then, the doctor will apply slight pressure to the cornea using a small instrument while he looks through a table-mounted microscope. A handheld tonometry device is also sometimes used and is relatively accurate. Tonometry is painless and poses virtually no risk to the cornea during this test.
* Ophthalmoscopy is a specific examination of the optic nerve, required for the diagnosis of glaucoma. It also helps with periodic examinations of the nerve valuable to follow the progress of the disorder during treatment. To perform ophthalmoscopy, the doctor dilates pupils with eye-drops and then uses an ophthalmoscope. This is a special instrument with a small light on one end to magnify and examine the optic nerve. Another type of ophthalmoscopy uses a specialized microscope that allows three-dimensional visualization of your optic nerve. Signs of a damaged optic nerve include cupping in its center and a loss of its normal pink color.
* Perimetry is a procedure where the patient wears a patch over one eye and looks straight ahead at a bowl-shaped white area. At the same time, the computer presents lights in fixed locations around the bowl. The patient indicates each time he or she sees a light, which is why perimetry is able to provide a map of the visual fields. The type of vision loss associated with glaucoma is relatively specific, and perimetry can detect the typical visual-field defects of glaucoma disorder.
A thorough eye examination including gonioscopy with a Goldmann or Zeiss goniolens is a prerequisite prior to undergoing specific tests for glaucoma. In glaucoma management, serial tests over several years have more value than a single one-time test for diagnosis. Therefore, it is important that the same type of test is repeated many times over a period of several years. The reason for this is that we are trying to ascertain whether a given target pressure has indeed stopped further damage to the eye. This determination is only possible if we have examinations from previous years to compare against, and it can show that there are no new findings or worsening. Therefore, one must maintain good long-term records and if you change physicians for any reason, it is important that you have all prior records forwarded to the current physician.
The newer tests for glaucoma
The visual field test depends upon patient responses. The new tests are nerve fiber analyzers, and these adopt a different objective strategy that is not dependent on patient responses. These tests measure the physical thickness of the nerve fibers in the retina. Since in glaucoma the nerve fibers are lost, patients with glaucoma are likely to have thinner nerve fiber layers. By measuring changes in nerve fiber layer thickness over time, these tests can detect glaucoma progression. The validity of these tests has been established in many peer-reviewed reports. Perhaps these tests will become the gold standards in the future as more professionals gain experience with these types of tests; however at present they are considered supplemental tests in glaucoma diagnosis at best. Going by the logic that more information is better than less, a reasonable argument is easy to get from these tests in addition to the traditional tests, even if their role in glaucoma management is debatable.