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Glaucoma Treatment overview Glaucoma is a chronic disorder that cannot be cured. Open-angle glaucoma often can be treated safely and effectively with medication or surgery, though lifelong therapy is almost always necessary. Decisions on when to start treatment are based on evidence of optic nerve damage, visual field loss, and risk factors (such as elevated intraocular pressure, or IOP, increasing age, and African-American or Hispanic background). The overall aim in the treatment of glaucoma is to prevent damage to the optic nerve by lowering IOP and maintaining it at a level that is unlikely to cause further nerve damage. The appropriate target for IOP is generally 25 percent below the IOP level at the time of diagnosis. If progressive damage is detected at the target IOP, a lower target is selected. Unfortunately, treatment cannot reverse optic nerve damage or improve vision. Acute closed-angle glaucoma is a medical emergency. During an acute attack of closed-angle glaucoma, IOP may be high enough to damage the optic nerve or obstruct one of the blood vessels carrying blood and oxygen to the retina. Unless IOP is lowered promptly, blindness can occur within one or two days. The goals of treatment are to protect the optic nerve and prevent a future attack in the other eye. IOP in the affected eye is lowered with medication followed by surgery, either laser (iridotomy) or conventional (iridectomy). In both cases, surgery involves making a tiny hole in the iris to allow a path for the flow of aqueous humor. Surgery is almost always successful, and repeat treatment is rarely necessary. A preventive iridotomy or iridectomy in the other eye is usually performed because of the high likelihood of a future acute attack in that eye. This section has more on:
Medication Two forms of medication are used to treat glaucoma: eyedrops and oral drugs. Eyedrops are the most common medication for glaucoma. In general, eyedrops are applied one to four times a day on a regular schedule. Five types of eyedrops are currently used: beta blockers, topical prostaglandins, carbonic anhydrase inhibitors, adrenergic agonists, and miotics. Drops can cause local side effects such as burning, stinging, tearing, itching, or redness in the eye. Because some of the drug is absorbed into the body, systemic side effects may occur but are less common than with oral medications. One example of a common side effect is that beta blocker eyedrops can lower blood pressure at the same time as they lower IOP. Systemic side effects can be minimized by carefully following instructions for using eyedrops, including placing a finger on the inside corner of the eye for two to three minutes to prevent the eyedrops from entering the nasal ducts. This section has more on:
Eyedrops Eyedrops to treat glaucoma include: Beta blockers. These drugs lower intraocular pressure (IOP) by reducing the production of aqueous humor. The most commonly used beta blocker is timolol (Timoptic). Newer beta blockers such as betaxolol (Betoptic), carteolol (Ocupress), levobunolol (Betagan), and metipranolol (OptiPranolol) are just as effective. Systemic side effects of beta blockers include slower heart rate, reduced blood pressure, reduced libido, anxiety, nausea and vomiting, and breathing difficulties. Topical prostaglandins. The topical prostaglandins bimatoprost (Lumigan), latanoprost (Xalatan), and travoprost (Travatan) reduce IOP by increasing drainage of aqueous humor. These medications appear to be at least as effective as the beta blocker timolol and are associated with fewer side effects. Consequently, topical prostaglandins are now the most frequently used drugs for glaucoma. Topical prostaglandins also are sometimes used in combination with another glaucoma medication to produce greater reductions in IOP. About 3 percent of people taking topical prostaglandins for six months or more experience gradual changes in eye color--from blue or green to brown. Other possible side effects include burning, stinging, and increased eyelash growth. Carbonic anhydrase inhibitors. Two carbonic anhydrase inhibitors are available as eyedrops: brinzolamide (Azopt) and dorzolamide (Trusopt). These eyedrops lower IOP by decreasing production of aqueous humor. They are used when other glaucoma medications are ineffective. Common side effects include fatigue, stinging in the eyes, and loss of appetite. Adrenergic agonists. Adrenergic agonists, such as dipivefrin (Propine) and epinephrine (Epifrin), can increase the drainage of aqueous humor but work primarily by decreasing its production. Possible side effects include burning in the eyes, enlarged pupils, and allergic reactions. Miotics. Miotics, such as pilocarpine (Isopto Carpine) and carbachol (Isopto Carbachol), increase the drainage of aqueous humor by improving its flow through the trabecular meshwork. Side effects of these drugs include nearsightedness and reduced night vision. Excessive tearing, eye pain, and allergic reactions may also occur. Combination agent. A medication containing both dorzolamide and timolol is available (Cosopt). This drug reduces the production of aqueous humor and has shown to be more effective in lowering IOP than either agent alone. However, a 2003 study found that dorzolamide-timolol did not lower IOP as effectively as bimatoprost. The drug is often used together with a topical prostaglandin to reduce IOP in patients in whom single-drug therapy has not been successful. Oral medications Acetazolamide (Diamox) and methazolamide, both carbonic anhydrase inhibitors, are the only glaucoma medications that are taken orally. Because of their side effects, they are generally used only when optic nerve damage continues despite the use of eyedrops at the highest tolerable dose. The drugs initially lower intraocular pressure (IOP) by 20 percent to 30 percent but are associated with significant systemic side effects (such as numbness or tingling in the hands and feet, malaise, and loss of appetite) and occasional serious complications (such as depression, kidney stones, diarrhea, and damage to blood cells). Surgery About 10 percent of people with open-angle glaucoma undergo surgery. They choose surgery because they prefer it or because they experience serious side effects from medications, do not respond adequately to drug treatment, are unable to take their medications properly, or have medical conditions or allergies that do not permit optimal drug therapy. The two most common surgical procedures are laser trabecular surgery and filtration surgery. While surgery cannot restore lost vision, it can reduce intraocular pressure (IOP) by improving the drainage of aqueous humor. As a result, surgery can halt the progression of optic nerve damage and vision loss. This section has more on:
Laser trabecular surgery In this procedure, 80 to 100 tiny laser burns are made in the area of the trabecular meshwork. The procedure increases the drainage of aqueous humor, most likely by stimulating the metabolic activity of trabecular cells. The procedure takes about 15 minutes and is performed on an outpatient basis using eyedrops for anesthesia. Postoperative complications are minimal and include eye inflammation, blurred vision, and minimal discomfort, which usually last for about 24 hours. It takes up to six weeks to determine whether the procedure has been effective. Medication is still required after surgery, but if the procedure reduces intraocular pressure (IOP) considerably, medication sometimes can be taken at a lower dose. About 40 percent of people need additional medication or some other form of surgery within five years. Filtration surgery Filtration surgery (trabeculectomy) uses conventional surgical instruments to open a passage through the trabecular meshwork so that aqueous humor can drain into surrounding tissues. The operation takes about 20 minutes, is performed on an outpatient basis under local anesthesia, and is relatively safe and long lasting. If necessary, the drainage flap created during the surgery can be loosened or tightened later on with a new laser procedure called suture lysis or with the use of special adjustable sutures. About half of patients are able to discontinue their glaucoma medication after filtration surgery; 35 percent to 40 percent still need some medication; and 10 percent to 15 percent need additional surgery, such as [shunts] or [cyclodestructive surgery]. Filtration surgery is associated with a risk of infection and bleeding in the eye and requires a longer recovery period than laser trabecular surgery. About one third of people develop cataracts within five years of filtration surgery. It is not clear whether the surgery itself causes the cataracts or whether they would have occurred anyway, but the cataracts can be surgically removed when necessary. Researchers are working to improve the effectiveness of filtration surgery. One of the most promising approaches is the use of antimetabolites (substances that block biological processes) such as mitomycin (Mutamycin) or 5-fluorouracil (Efudex). These drugs interfere with normal wound healing so that the openings created by the procedure do not close. Shunts If filtration surgery is unsuccessful, one alternative is to drain excess aqueous humor using a shunt made of plastic tubing. The shunt is implanted into the front chamber of the eye, and the aqueous humor drains onto a plate sewn onto the side of the eye. Fluid on the plate is then absorbed by the tissues surrounding the eye. Cyclodestructive surgery Cyclodestructive surgery uses a laser to destroy the ciliary body, which produces aqueous humor. The procedure does not require an incision, so normal activity can be resumed earlier than after filtration surgery. Cyclodestructive surgery is usually used only when other measures have failed. |
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