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Glaucoma - Symptoms & Treatment

Glaucoma is the name for a group of eye diseases in which the optic nerve is damaged. In the worst cases, the damage can lead to blindness, but this need not happen if glaucoma is detected and treated early.

Glaucoma occurs in several forms: chronic open-angle (primary), acute angie-closure, low tension (normal lOP that is too high for a particular person), congenital (inherited as an autosomal recessive trait), and secondary to other causes.

Glaucoma is the second most common cause of blindness in the United States. Glaucoma affects an estimated 3 million Americans, with 120,000 blind due to the condition. Elsewhere in the world, glaucoma treatment is less available, and glaucoma ranks as a leading cause of blindness just about everywhere. Even if people with glaucoma do not become blind, vision can be severely impaired.

Causes

The cause of glaucoma varies according to the type of disorder:

• .Chronic open-angle glaucoma results from overproduction of aqueous humor or from obstructed outflow of aqueous humor through the trabecular meshwork or the canal of Schlemm. This form of glaucoma frequently runs in families and affects 90% of all patients with glaucoma.
• Acute angle-closure (narrow-angle) glaucoma results from obstructed out­flow of aqueous humor due to anatomically narrow angles between the anterior iris and the posterior corneal surface, shallow anterior chambers, a thickened iris that causes angle closure on pupil dilation, or a bulging iris that presses on the trabeculae, closing the angle. Adhesions in the angle, referred to as peripheral anterior synechiae, may be the cause.
• Secondary glaucoma can result from uveitis, trauma, or drugs (such as steroids). Neovascularization in the angle can result from vein occlusion or diabetes.

Signs and symptoms

Most people with glaucoma don't have any symptoms of the disease. You might not realize that you're losing vision until it's too late. Half of all people with loss of vision caused by glaucoma are not aware they have the disease. By the time they notice loss of vision, the eye damage is severe.

Rarely, an individual will have an acute attack of glaucoma. In these cases, the eye becomes red and extremely painful. Also, nausea, vomiting and blurred vision may occur.

Diagnosis

Loss of peripheral visual field, cupping of the optical disk, and increased lOP are the triad of signs that indicate glaucoma. Relevant diagnostic tests include the following:

• Tonometry (using an applanation, Schietz, or air-puff tonometer) measures lOP and provides a baseline for reference.
• Pachymetry. Your eyes are numbed for this test, which uses an ultrasonic wave instrument to gauge the thickness of each cornea. The thickness of your corneas is an important factor for accurately diagnosing glaucoma. If you have thick corneas, your eye pressure reading may seem high even though you don't have glaucoma. Conversely, people with thin corneas can have low pressure readings, but have glaucoma.
• Other tests. To distinguish between open-angle glaucoma and angle-closure glaucoma, your eye doctor may use a technique called gonioscopy (go-ne-OS-kuh-pe), in which a special lens with an angled mirror is placed on the eye to inspect the drainage angle. Another test, tonography, can measure how fast fluid drains through the trabecular meshwork.

Treatment

Glaucoma may be successfully treated by medication, surgery, or both. Treatment depends on the type of glaucoma and its severity, and the underlying medical conditions, age, and health of the patient. Patients must work with their doctors to find the most effective treatment.

Medication

Glaucoma medications are either oral or topical. There are five types of topical medications that achieve these purposes:

• Miotics increase the outflow of fluid. These include: Isopto®Carpine, Ocusert®, Pilocar®, and Pilopine®.
• Epinephrines increase the outflow of fluid. These include Epifrin® and Propine®
• Beta-Blockers reduce the amount of fluid. These include Betagan®, Betimol®, Betoptic®, Ocupress®, Optipranalol®, and Timoptic®.
• Carbonic Anhydrase Inhibitors and Alpha-Adrenergic Agonists reduce the amount of fluid. These include: Alphagan®, Iopidine®, and Trusopt®.
• Prostaglandin Analogs increase the outflow of fluid through a secondary drainage route. These include: Lumigan®, Rescula®, Travatan®, and Xalatan®.

The most common type of oral medication are Carbonic Anhydrase Inhibitors, which include Daranide®, Diamox®, and Neptazane®.

Argon Laser trabeculoplasty :- In argon laser trabeculoplasty, an argon laser beam is focused on the trabecular meshwork of an open angle. This produces a thermal burn that changes the surface of the meshwork and increases the outflow of aqueous humor.

Laser peripheral iridotomy is often used to treat angle-closure glaucoma. The laser creates a small hole in the iris, allowing the aqueous to flow more freely within the eye.

Surgical treatment

Sometimes all the above treatments do not allow control of the pressure and therefore a trabeculectomy (as outlined above in primary open angle glaucoma) may be required.

Prevention

There is no way to prevent open angle glaucoma, but vision loss from open angle glaucoma can be prevented. Early diagnosis and careful management of the condition, if diagnosed, are the keys to preventing vision loss.

Most people with open angle glaucoma have no symptoms.  All persons over 40 should have an eye examination at least 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.

People at high risk for acute glaucoma may opt to undergo iridotomy before having an attack. Patients who have had an acute episode in the past may undergo the procedure to prevent recurrence.

Eating vitamin-rich fruits and vegetables, taking a vitamin supplement, protecting eyes from injury, and getting medical treatment for systemic illnesses promote good eye health.