Surgery for open-angle glaucoma
A clear liquid called aqueous humor circulates inside the front portion of the eye. In open-angle glaucoma, this liquid does not flow efficiently through the eye’s sponge-like drainage system (known as the trabecular meshwork). When this liquid fails to drain properly, pressure builds within the eye. The medical term for this pressure is intraocular pressure. Such pressure inside the eye may damage the optic nerve and lead to vision loss. Medications, laser surgery, or other glaucoma surgeries may be used to lower and control the eye pressure.
When is surgery necessary?
When medications or laser treatment cannot lower eye pressure enough, surgery is usually recommended. Of the possible procedures, glaucoma filtration surgery, also called trabeculectomy, is the most common.
How is a trabeculectomy done?
In performing a trabeculectomy, your ophthalmologist (Eye M.D.) makes a small flap in the white of the eye, called the sclera. A filtration bleb, or reservoir, is created under the conjunctiva, the thin and clear coating that covers the sclera. The aqueous humor inside the eye can then drain through the flap to collect in the bleb, where it is absorbed into the lymph and blood vessels around the eye.
After the bleb is carefully constructed, the incision is closed with tiny stitches. Some of these stitches may be removed after surgery to increase fluid drainage.
Drugs to reduce scarring are often applied during and after surgery.
What can you expect if you have the surgery?
BEFORE SURGERY
You will continue to use your glaucoma medications until just prior to surgery. If you take aspirin or any products containing aspirin, these should be discontinued at least 7–10 days prior to surgery. If you take coumadin, you will need to discontinue this medication 3–5 days prior to surgery. The precise timing for stopping and resuming your medication is usually coordinated with your internist or cardiologist.
THE DAY OF SURGERY
A trabeculectomy is done as an outpatient surgery with a local anesthetic to prevent discomfort during the operation. You may be given a sedative to help you relax. General anesthesia is rarely necessary. The procedure is usually performed in less than an hour, but it may take longer if you have had previous eye surgery, if your eye is inflamed, or if abnormal blood vessels are present.
AFTER SURGERY
Postoperative care is as important to the long-term success of the operation as the surgery itself. In follow-up appointments, your ophthalmologist will examine the filtering bleb, the external appearance of the eye, your eye pressure, and the back of your eye. You should avoid lifting, bending, or straining after surgery until your eye pressure stabilizes.
Pain is unusual after surgery, although your eye may feel tender and sensitive. A non-aspirin pain reliever is usually sufficient to treat any discomfort. Sudden, severe, or deep-seated pain, especially if it is associated with loss of vision, should be reported to your ophthalmologist immediately.
Eye pressure is adequately controlled in three out of four people. Although follow-up visits are still necessary after surgery, many people will no longer need to use eyedrops. However, if the new opening closes or too much fluid drains from the eye, additional surgery may be necessary.
What will my vision be like?
Vision may fluctuate daily after surgery. Generally your vision is blurry for several weeks. There may or may not be a change in your eyeglass prescription after surgery.
If a cataract is present or another complication exists, vision may not return to what it was before surgery. Surgery cannot restore vision already lost from glaucoma.
Complications
As with all surgeries, there are risks associated with a trabeculectomy. One of the most common complications is scarring. Other complications include:
- infection;
- bleeding;
- wound leakage;
- over filtration;
- cataract;
- loss of vision.
Although the success rate is quite high, sometimes a single surgical procedure cannot halt the progression of glaucoma. Another surgery and/or continued treatment with medications may be necessary.
An eye that has undergone a trabeculectomy and has a functioning bleb will always be susceptible to infection. A red, uncomfortable eye may be a sign of infection and requires urgent medical attention.
Are there alternatives to glaucoma filtration surgery?
Depending on the type and severity of glaucoma and how much the pressure needs to be lowered to stop its progression, several other treatment procedures are available.
AQUEOUS SHUNT SURGERY
When the risk is high that a trabeculectomy will fail, especially in neovascular glaucoma or glaucoma associated with inflammation in the eye, an aqueous shunt surgery may be recommended. An aqueous shunt is a small tube or valve placed in the eye through a tiny incision. The shunt drains excess fluid into a small reservoir placed on the eye.
This surgery, like a trabeculectomy, is an outpatient surgical procedure. Risks of surgery and postoperative care are similar to those for a trabeculectomy.
LASER TRABECULOPLASTY
There are two types of laser trabeculoplasty: argon laser trabeculoplasty (ALT) and selective laser trabeculoplasty (SLT). These procedures use different lasers to treat the drainage channel. Holes are not created; instead the drain is stimulated to work more effectively.
Both lasers are effective in lowering eye pressure and do so more than 75 percent of the time, however the effect of both kinds of trabeculoplasty can lessen over time. Five years after treatment up to half of those treated will have increased eye pressure. SLT uses lower energy levels and allows for treatment in the future.
The procedure is performed in an ophthalmologist’s office with an eyedrop anesthetic and can usually be completed within 10 minutes. Since eye pressure is monitored after surgery, the total office time required may be two to three hours. A few people experience a rise in eye pressure shortly after laser trabeculoplasty. There is usually little pain associated with this laser procedure and few complications.
CYCLOPHOTOCOAGULATION
When attempts to increase the amount of fluid draining from the eye through the trabecular meshwork fail, another treatment option is to reduce the amount of fluid entering the eye. Cyclophotocoagulation is a procedure that uses a laser beam to treat parts of your eye’s ciliary body. The ciliary body is a band of tissue, located behind where the cornea meets the white part of your eye, that produces the aqueous humor. Treating parts of the ciliary body can reduce the production of aqueous humor, thus lowering eye pressure.
Cyclophotocoagulation is generally used to treat advanced or aggressive open-angle glaucoma. It is usually used after other treatments have proven unsuccessful. The procedure is performed with local anesthesia. When the anesthetic wears off after the procedure, you may experience some pain or discomfort. Your ophthalmologist may prescribe medication such as Tylenol with codeine or Vicodin® to help ease the discomfort.
In follow-up exams after cyclophotocoagulation, your ophthalmologist will check for inflammation and monitor the pressure in your eye.
Risks associated with cyclophotocoagulation include pain, inflammation, and decreased vision. While the risks may sound unpleasant, keep in mind that unless severe glaucoma is treated, you run the risk of losing vision permanently.
Loss of vision can be prevented
Vision loss from glaucoma can be prevented if it is caught and treated in time. Glaucoma filtration surgery is the most common glaucoma surgery. Although complications may occur, most are treatable. While glaucoma treatments cannot restore vision already lost from glaucoma, early detection and treatment offer the best chance of preserving vision.
