When it is not possible to lower the intraocular pressure adequately with eye drops or oral drugs, eye surgery may be advised. In some situations, you and your doctor may decide to try surgery instead of using drops. There are two types of surgery: laser surgery and incisional surgery.
Laser Surgery
This is performed in a doctor's office or an eye clinic. In laser surgery, the surgeon uses a concentrated high-energy beam of light to make changes to the eye to help relieve the intraocular pressure.
The three types most frequently used are:
Trabeculoplasty —This procedure is most often used to treat open-angle glaucoma. Using the laser, the surgeon will make many small microscopic burns in the drainage area of the eye. This will allow the aqueous fluid to drain more freely. The procedure takes 10-20 minutes, and you can resume normal activities right after it. It takes about 2-3 weeks before one can see the maximum effect from the surgery.
Iridotomy —This surgery is frequently used to treat angle-closure glaucoma or to prevent it in patients who have very narrow drainage angles. Using the laser, the surgeon will make a small hole in the iris. This will allow the aqueous fluid to flow more freely inside the eye and help to widen the drainage angle between the cornea and iris.
Cyclophotocoagulation —This procedure is usually reserved for more advanced or aggressive cases of glaucoma that are refractory to other treatments. Using either the laser or a freezing probe, the surgeon will destroy selected areas of the ciliary body—the part of the eye that produces fluid. This will reduce the production of aqueous fluid.
The surgeon will place eye drops into your eyes to numb them. You will sit facing the laser machine. Using a special lens held to the front of your eye, the surgeon will focus the high-energy beam of light at specific structures in your eye. You may see flashes of bright green or red light. The process often takes just a few minutes.
You cannot rub your eyes for at least 20 minutes or until the numbing eye drops have worn off. You may experience some local eye irritation. You may need someone to drive you home after the procedure, but most people can resume their normal activities within a day after the procedure. Your vision will probably be blurry for one to two days after the procedure.
Mechanical shunts —In advanced cases, sometimes a a placement of a mechanical shunt is the best option. Shunts are small silicone tubes that are inserted into an eye to help drain the aqueous fluid.
Incisional Surgery
Also known as filtering surgery, or trabeculectomy, incisional surgery involves the use of tiny instruments to make a tiny hole in the sclera, or white of the eye where it meets the cornea. The aqueous humor can now drain out through the hole and be reabsorbed into the bloodstream. This reduces the pressure in the eye. In some cases, the surgeon may place a valve in the eye through a tiny incision. These valves act as a regulator for the buildup of fluid within the eye, allowing fluid to flow out and be reabsorbed.
Incisional surgery is usually performed in an operating room with local anesthesia. The surgeon will make the small incision in the eye to allow for a slow release of aqueous fluid. If necessary, the surgeon will place the tiny valve in the eye through an incision. The surgeon will also often cut out a small hole in the iris to help prevent the iris from blocking the hole.
You will need someone to drive you home after the procedure. In addition, you may need to wear a patch and use eye drops following surgery. Avoid activities that expose your eye to water, such as swimming and showering, as recommended by your doctor. Also avoid strenuous activities, as recommended by your doctor.