What is a Trabeculectomy?
When treatment with eye drops, pills, or laser surgery does not lower intraocular pressure to a safe level, your ophthalmologist may determine that glaucoma surgery should be performed. One way to reduce pressure in an eye with glaucoma is to make a new drain in the eye. This type of surgery is called a trabeculectomy.
During this operation, a tiny piece of the wall of the eye, which may include the trabecular meshwork (the natural drain), is removed by the surgeon. This opens a new drain which creates a bypass for the trabecular meshwork to reduce eye pressure. The eye pressure is reduced because fluid can now drain with relative ease through the new opening into a reservoir (bleb) underneath the conjunctiva (which comprises the surface of the eye). The fluid is then absorbed by the body.
The goal of trabeculectomy is to lower eye pressure. By lowering eye pressure, it is hoped that the operated eye will be spared further glaucoma damage and can maintain its vision. Although vision sometimes can improve following trabeculectomy, in most eyes it remains unchanged. Occasionally, there can be loss of vision.
What do I need to do before a trabeculectomy?
Eye drops and pills which are being used to lower intraocular pressure are continued until the time of surgery unless directed otherwise by Dr. Smith. Occasionally, an eye drop or pill may be discontinued for as long as two weeks before the surgery. It is particularly important to discontinue the use of aspirin, or any pills containing aspirin, at least 7 days before surgery, since use of aspirin can cause undesirable bleeding at the time of surgery.
What type of anesthesia is used?
To relax the patient and reduce discomfort, a trabeculectomy is usually done under local anesthesia. An injection of local anesthetic through the eyelid numbs the eye completely so that it will not move during surgery, and there is no discomfort. Sometimes a general anesthetic is used, in which the patient is put to sleep for the operation. Local anesthesia offers several advantages. There may be less pain after surgery, and there is no sore throat from the airway tube used in general anesthesia. Patients quickly return to normal alertness without the nausea often felt after general anesthesia. With local anesthesia, there is less risk than with a general anesthetic, especially in the elderly or those with health problems. The surgery itself takes less than one hour in most cases.
What happens to the eye after a trabeculectomy?
After trabeculectomy, the eye generally is covered by an eye patch and protected by a plastic shield overnight. On the morning following the surgery, it is removed and the eye is examined by your ophthalmologist. Eye drops are then prescribed to relax the muscles in the eye, prevent infection, and reduce inflammation. Occasionally, a pill may be prescribed, as well, to further reduce inflammation. It is important to take these as directed by Dr. Smith since they can make a great deal of difference in the success of the procedure.
For several weeks following the surgery, your ophthalmologist will observe your eye closely and examine you frequently. During this time, the eye may have a very low pressure and be unstable. It is important to protect the eye and avoid lifting heavy objects, bending or straining. Your ophthalmologist may prescribe a cough suppressant if you have a cough or a stool softener to ease bowel movements. In addition, it is important to keep the eye clean and dry since the eye may be susceptible to infection immediately after the surgery. Your ophthalmologist may also recommend that you sleep on the side opposite the operated eye and protect it during sleep by wearing a plastic shield.
Because it is not possible to know the precise size of the opening to make in the eye to drain fluid, sometimes too much fluid may drain after surgery. If this happens, it usually lasts for only a few days, but during that time the eye pressure may be too low. It is difficult for the eye to adjust to this low eye pressure and it can cause problems if left untreated, such as formation of a cataract.
Another problem which can occur after trabeculectomy relates to natural healing. The natural response of the body to an injury is for healing to occur by formation of a scar. If the healing response is strong, too much scar tissue will be produced. The scar tissue can overgrow the site of the operation and seal the drainage hole. If this occurs, the eye pressure will rise again and require a return to eye drops, pills or possibly another operation to reduce the pressure.
Is there success with trabeculectomy?
Although the results of the trabeculectomy depend on numerous factors and can vary greatly, as a general rule approximately 70% of operated eyes will have satisfactory eye pressure and no need for medication one year after surgery. If eye drops are added, over 90% of eyes will have a satisfactory lowering of eye pressure.