Trabeculectomy

What Is Trabeculectomy?

During a trabeculectomy, an artificial drain is created for the aqueous humor. The aqueous humor is directed under the conjunctiva of the sclera, the white sclera of the eye. A "filtering bleb" that is visible from the outside is created in which the aqueous humor accumulates. This reduces the pressure inside the eye.

Trabeculectomy is the surgical method that is most effective in lowering intraocular pressure. However, the procedure is often associated with complications and extensive follow-up care. A common complication of trabeculectomy is too much reduction in intraocular pressure. In addition, the filtering bleb also causes problems frequently. Cysts and infections can develop there, for example.

For Which Patients Is Trabeculectomy an Option?

A trabeculectomy is the surgical method of choice when the intraocular pressure in glaucoma can no longer be lowered with medication, laser treatment, or minimally invasive surgical procedures.

Trabeculectomy is usually performed immediately without prior laser or other treatment in patients with advanced open-angle or narrow-angle glaucoma with damage to the optic nerve or retina and glaucoma with very high pressures.

Trabeculectomy is also an option in cases of intolerance to eye drops. With minimally invasive procedures such as canaloplasty, additional eye drops are often necessary to achieve the desired reduction in eye pressure.

The Procedure of the Surgery

Before the surgery, an informing consultation takes place. Patients must discontinue pressure-lowering eye drops two weeks before the procedure to allow the ocular surface to recover before surgery since it is irritated by the many years of eye drop treatment. Instead, anti-inflammatory eye drops are given a few days before surgery. This prevents complications.

Until the surgery, when the pressure-lowering eye drops have been discontinued, alternative glaucoma treatment with acetazolamide tablets is required instead. However, the tablets may have side effects.

The procedure is carried out under local or general anesthesia and takes 20 to 30 minutes. First, the surgeon creates an approximately 4 x 4 mm rectangular opening in the sclera that extends to the edge of the clear cornea. Below this is the trabecular meshwork at the angle of the eye chamber. The aqueous humor drains typically through the trabecular meshwork. Next, the surgeon creates a connection from the sclera through the trabecular meshwork into the eye's anterior chamber and removes another small triangular piece of the iris to prevent it from obstructing the drainage. Then the surgeon covers the scleral opening again with a scleral flap and sutures the flap in place.

Now the aqueous humor can pass under the conjunctiva of the sclera through this connection in front of the anterior chamber of the eye. A filtering bleb is created there in which the aqueous humor accumulates.

During surgery, a medication, usually mitomycin C, is applied to the surgical site to prevent scarring during the healing phase.

The procedure is followed by a three to four days inpatient stay. Wound healing, intraocular pressure, and the filtering bleb must be carefully monitored during this time. There is a risk that the drain may close entirely or partially during healing. In that case, measures must be taken the days after the surgery to keep the drain open - for example, an injection with 5-fluorouracil or separation of individual sutures with a laser.

Further follow-up is also needed after the inpatient stay. If the eye pressure rises again, the outflow of the aqueous humor can be improved by minor laser interventions.

In addition, patients must take anti-inflammatory eye drops for several months after surgery to prevent scarring.

What Is the Experience?

Trabeculectomy is still the method that best lowers intraocular pressure. A pressure reduction to 13 to 14 mmHg is possible with this method. The desired pressure reduction is achieved in about 70 percent of patients without additional eye drops. Unfortunately, minimally invasive procedures often fail to achieve sufficient pressure reduction without additional eye drops.

Trabeculectomy also scores well in long-term studies. In 80 percent of patients, pressure reduction was still sufficient 20 years after surgery.

However, the success of the surgery depends mainly on preparation and careful follow-up. For example, surgery has long been performed almost exclusively using drugs that inhibit scarring.

Are There Alternatives?

Other minimally invasive treatments are available besides trabeculectomy for mild to moderate glaucoma. These do not lower pressure as effectively as trabeculectomy but have a lower risk of complications and significantly less follow-up.

Laser treatment of the trabecular meshwork, laser trabeculoplasty, can improve chamber outflow. However, this does not permanently lower intraocular pressure but is suitable as a temporary solution in some instances.

A relatively new minimally invasive surgical procedure is canaloplasty. In canaloplasty, the Schlemm's canal through which aqueous humor drains is widened with a microcatheter, and a suture is inserted into the canal. This is done to restore natural aqueous humor outflow and keep the canal permanently open.

For some complicated glaucoma, for example, congenital glaucoma, trabeculectomy is not suitable. In these cases, implant surgery, which drains the aqueous humor via a tube, or cyclodestructive surgical methods, in which the ciliary body is sclerosed, can be considered. In addition, sclerotherapy of the ciliary body decreases aqueous humor production. Surgical procedures are also used when trabeculectomy does not achieve sufficient pressure reduction.

What Risks Are Connected to Trabeculectomy?

A relatively high risk of complications is connected to trabeculectomy. Therefore, careful preparation and follow-up care and an experienced surgeon are especially important.

There will be insufficient pressure reduction if the scleral flap is sewn too tightly during surgery; if the scleral flap is too loose, there will be too much pressure reduction.

Too much intraocular pressure lowering is one of the most common complications in trabeculectomy. Too low intraocular pressure can damage the eye and lead to choroidal detachment in the long run. This can cause vision to deteriorate.

If too much of the iris is removed during the procedure, glare sensitivity of the eye will occur.

Other complications can occur after the surgery. For example, one to two days after surgery, the eye's choroid may swell, especially in very old patients, those with myopia, or those with very high eye pressures.

If no measures are taken, scars may form after the surgery. This worsens the drainage of the aqueous humor, and the intraocular pressure rises again.

The filtering bleb also causes problems more often. Cysts, fistulas, and infections can develop, for example.

In the first period after the surgery, patients must also expect a deterioration of vision due to surgery-related astigmatism and the anti-inflammatory eye drop therapy.

Which Clinics Are Specialized?

For a trabeculectomy, it is best to go to an eye clinic specializing in glaucoma surgery. You will find experienced surgeons there who perform the surgery regularly.

We will help you find an expert for your condition. All listed doctors and clinics have been reviewed by us for their outstanding specialization in trabeculectomy and are awaiting your inquiry or treatment request.

Sources:

• Augenheilkunde, F. Grehn, 31. überarbeitete Auflage, Springer Verlag 2012
• Hoffmann E.M., Pfeiffer N. (2018). Trabekulektomie mit Mitomycin C. Ophthalmologe 2018; 115:521-532
• Matlach J., Klink T. (2015). Trabekulektomie versus Kanaloplastik. Ophthalmologe 2015; 112:325-331
• Nassri et al. (2020). Therapieerfolg von Kanaloplastik und Trabekulektomie durch denselben Operateur mit demselben Erfahrungslevel im Langzeitverlauf. Ophthalmologe 2020; 117:1025-1032
• Reznicek L. et al. (2016). Möglichkeiten und Grenzen der operativen Glaukomtherapie. Ophthalmologe 2016; 113:833-837
• Taruttis T. et al. (2018). Vergleich von Trabekulektomie und Kanaloplastik. Drucksenkender Effekt und postoperatives Komplikation- und Interventionsspektrum. Ophthalmologe 2018; 115:137-144