High doses or long-term use of prednisone can cause glaucoma, a serious eye disease. Glaucoma may be painless, but it can lead to permanent vision loss or even blindness. People taking prednisone should alert the prescribing physician to any family history of glaucoma and have a regular eye examination that includes a glaucoma test.
What Is Glaucoma?
Glaucoma is the build up of fluid pressure, called intraocular pressure, inside the eye. This increase in pressure could damage the optic nerve. The optic nerve is light-sensitive tissue at the back of the eye composed of nerve fibers that connect the retina to the brain. The optic nerve is essential to vision, as it transmits images to the brain.
Glaucoma is diagnosed after damage to the optic nerve occurs. High intraocular pressure may cause vision to worsen and eventually lead to blindness in a few years. Some people may have increased eye pressure, yet no damage to the optic nerve, and may never develop glaucoma. However, high intraocular pressure does indicate an increased risk of developing glaucoma.
Types of GlaucomaThere are several types of glaucoma, including secondary (complication of another condition or with certain medications such as prednisone), open-angle, angle-closure, congenital (present at birth) and low-tension or normal-tension (associated with normal eye pressure).
- Open-angle glaucoma. This is the more common form of glaucoma and is sometimes called wide-angle glaucoma. In this form of the disease, the flow of eye fluid through the eye drain (trabecular meshwork) occurs too slowly. The fluid then builds up inside the eye, increasing pressure.
- Secondary glaucoma. This type of glaucoma is less common than open-angle in the general population, but is more common in people with IBD who are taking prednisone or other corticosteroids. It may also occur as a complication of another condition such as surgery, advanced cataracts, eye tumors, uveitis or diabetes. Secondary glaucoma can be of the open-angle or angle-closure type.
- Angle-closure glaucoma. In this type of glaucoma, part of the iris blocks fluid from leaving the eye through the trabecular meshwork. Fluid builds up suddenly, causing an abrupt increase in eye pressure, severe pain and nausea, blurred vision and eye redness. If not treated promptly, blindness can occur in a few days.
Persons at Risk for GlaucomaPersons at a higher risk for glaucoma include:
- People taking corticosteroids
- African Americans older than age 40
- People older than age 60, especially Hispanics
- People with a family history of glaucoma
- People with poor vision, high blood pressure, heart disease, retinal detachment, eye tumors and eye inflammations such as chronic uveitis and iritis
In many cases, glaucoma may be present without any symptoms. By the time such symptoms as the loss of peripheral or side vision occurs, the disease has already progressed considerably. An eye exam every one to two years may help in detecting glaucoma early. Those taking corticosteroids should talk to their healthcare provider about how often to get an eye exam.
Glaucoma is diagnosed through two simple and painless tests. The first test is dilation. The doctor puts drops in the eyes that dilate the pupils. When the pupils are large, the doctor can use a light to see to the retina at the back of the eye and look for signs of glaucoma or other disorders. When the eyes are dilated, vision is blurry. Some eye doctors may use newer techniques, such as retinal imaging, which takes a high-resolution picture of the eye without the need for dilation.
The second test is tonometry. During an initial tonometry test (pneumotonometry), a machine "flattens" the cornea with a small puff of air against the eye. If this test shows any abnormalities another type of tonometry test may be performed.
Treating GlaucomaEye drops are used to reduce the volume of fluid in the eye or increase its flow out of the eye. These drops must be used several times a day and side effects include headaches, stinging, burning and redness.
Laser surgery may be used to remove the blockage or increase fluid outflow from the eye. In trabeculoplasty, the trabecular meshwork is pulled open; in iridotomy, outflow is increased by making a hole in the iris; and in cyclophotocoagulation, the eye is treated to reduce fluid production. Side effects from laser surgery can include inflammation. The procedure may need to be repeated.
In microsurgery, an opening is created in the eye to help excess fluid drain. This treatment is often used only after other treatments are not successful. Side effects can include inflammation, cataract and cornea problems.
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