What Is Glaucoma?
Glaucoma encompasses a group of eye diseases that can damage the optic nerve, which carries information to the brain. Many of these conditions are caused by increased pressure in the eye or intraocular pressure. Glaucoma is the second leading cause of blindness worldwide, but the leading cause of blindness in African Americans. In many cases, if diagnosed and treated early, blindness can be avoided. Risk of glaucoma grows as people age. It affects 1 in 200 people aged fifty and younger, and 1 in 10 over the age of eighty. With early-enough diagnosis, it is possible to arrest the development or slow the progression using medical and surgical means.
What Causes It?
Of the four main types of glaucoma, the most common type is open-angle or chronic glaucoma. There is no known cause for open-angle glaucoma, but it tends to run in families and is more prevalent in people of African descent. Glaucoma is sometimes called the “silent thief of sight” because the loss of vision normally occurs gradually over a long period of time and is not recognized until the disease is quite advanced and substantial damage to the optic nerve has already been done. Once lost, this damaged visual field cannot be recovered.
Angle-closure or acute glaucoma occurs when there is a sudden blockage to the passage of fluids exiting the eye, causing a quick, painful rise in the pressure within the eye (intraocular pressure). This type of glaucoma is considered a medical emergency that must be handled immediately. Dilating eye drops and certain medications may trigger an acute glaucoma attack.
Congenital glaucoma is often hereditary and is present from birth. It is caused by abnormal development of the fluid outflow channels in the eye.
The last type of glaucoma, secondary glaucoma, can be caused by any one of several factors: drugs such as corticosteroids, eye diseases such as uveitis or even systemic diseases.
Symptoms vary widely between the four types of glaucoma. With open-angle glaucoma, most people have no symptoms or may only notice some gradual loss of peripheral vision over time. Angle-closure glaucoma, however, can have sudden and severe pain in one eye or perhaps decreased or cloudy vision with rainbow halos around lights. Eyes may feel swollen or may be red and nausea and vomiting is possible. These symptoms may come and go or may get steadily worse over time.
Congenital glaucoma is usually first observed as a cloudiness in the front of the eye, or enlargement of one or both eyes as early as the age of two or three months. Red eyes, excessive tearing or sensitivity to light are also indications that the child needs their eyesight to be assessed.
Assessment and Diagnosis
Glaucoma is typically diagnosed during a complete eye exam. While the pupil is dilated, the doctor can examine the inside of the eye. Although abnormal intraocular pressure is one common symptom of the disease, it is not enough alone to either diagnose or rule out glaucoma, since about 25% of patients have normal pressure levels in the eye even with the disease. Tests used in the diagnosis of glaucoma include:
- Gonioscopy (use of a special lens to see the outflow channels of the angle)
- Tonometry test to measure eye pressure
- Optic nerve imaging (photographs of the inside of the eye)
- Pupillary reflex response
- Retinal examination
- Slit lamp examination
- Visual acuity
- Visual field measurement
Treatment of Glaucoma
Reducing eye pressure is the first goal of treatment. This can be accomplished by using medications, laser treatments, surgery or a combination of these treatments.
Most people with open-angle glaucoma can be treated successfully with eye drops or a combination of eye drops and medication. Some patients need treatment such as a laser treatment to help open the fluid outflow channels. Others may need traditional surgery to open a new outflow channel.
An acute angle-closure attack is a medical emergency. Blindness can occur in a few days unless properly treated. If drops, pills and medicine given through a vein (by IV) are not effective, then an emergency operation called an iridotomy may be needed. This procedure uses a laser to open a new channel in the iris. A new channel both relieves immediate pressure and prevents another attack.
Congenital glaucoma is almost always treated with surgery with the patient under anesthesia.
Prevention and Prognosis
There is no way to prevent open-angle glaucoma, but you can prevent vision loss from the condition. Early diagnosis and careful management are the keys to preventing vision loss. Although the condition cannot be cured, most patients with open-angle glaucoma can manage their condition and will not lose vision. It’s important to carefully follow up with your doctor.
Most people with open-angle glaucoma have no symptoms. Everyone over age 40 should have an eye examination at least once every 5 years, and more often if in a high-risk group. Those in high-risk groups include people with a family history of open-angle glaucoma and people of African heritage.
In the case of angle-closure glaucoma, rapid diagnosis and treatment of an attack is key to saving your vision. Seek emergency care immediately if you have symptoms of an angle-closure attack. Call your health care provider if you have severe eye pain or a sudden loss of vision, especially loss of peripheral vision.
Early diagnosis and treatment is important when faced with a case of congenital glaucoma. If surgery is done early enough, many patients will have no future problems.
If you have the risk factors associated with glaucoma, including having a family history of the disease or if you are African American and have not been screened for the condition, call for an appointment with your health care provider. Early detection and treatment can make a difference in whether you retain your sight or lose it.
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