Evidence Based

Trabeculectomy Surgery for Glaucoma

Trabeculectomy is a surgical procedure that lowers the pressure inside your eye, called intraocular pressure (IOP). 

Eye pressure increases when the fluid inside of your eye (aqueous humor) cannot drain properly through the trabecular meshwork. The trabecular meshwork is a sponge-like structure located in the drainage angle, where the majority of aqueous humor leaves the eye. High IOP causes damage to your optic nerve, which results in progressive vision loss starting with your peripheral (side) vision.

Glaucoma therapies aim to lower eye pressure, which in turn slows down the progression of the disease. Many patients begin treatment with medicated eye drops. The surgeon may also perform a laser procedure to increase fluid drainage. Trabeculectomy is often performed if the eye pressure is not low enough with these therapies.

How Is Trabeculectomy Performed?

Trabeculectomy aims to create an alternate channel for aqueous fluid to leave the eye if the trabecular meshwork becomes blocked. This way, fluid does not build up inside your eye. Trabeculectomy surgeries take about an hour and are usually performed under local (sometimes general) anesthesia. 

During the procedure, the surgeon takes the following steps:

  • To create a channel for aqueous to flow through, the surgeon creates a small hole in the wall of your eye. 
  • Then the surgeon creates a small flap in your sclera, which is the tough, white part of your eye. This flap is made in the top of the sclera, which is hidden underneath your upper eyelid. The flap helps control the flow of fluid. The surgeon partially closes the scleral flap with sutures.
  • The conjunctiva is the layer of tissue covering your sclera. The surgeon forms a bleb in the conjunctiva, a small blister of tissue that collects aqueous fluid draining out of the eye. Your body can then absorb this fluid. 
  • After surgery, the doctor applies medication such as mitomycin c or 5-fluorouracil to prevent scarring. This helps keep the new drainage system open.
Icon of a dry, red eye

Side Effects & Complications

Serious complications are rare with trabeculectomy. Some potential complications of this surgery include:

  • Eye infection (including endophthalmitis, which is a severe infection inside the eye)
  • Bleb leak
  • Bleb scarring
  • Ptosis (eyelid droop)
  • Hemorrhage (bleeding) in the eye
  • Vision loss
  • Hypotony (abnormally low eye pressure)
  • Choroidal or retinal detachment

As with other types of eye surgeries, trabeculectomy may also increase your risk for cataract formation.

Icon of eye with test tool

Recovery

Recovery usually takes a few weeks, up to about two months. Here are some things to expect during this period:

  • Use the prescribed steroid and antibiotic drops as directed. These medications reduce your risk for infection and inflammation. 
  • Use eye shields while sleeping and avoid rubbing your eyes.
  • Avoid heavy physical activity.
  • Depending on how quickly you heal, plan to take the week off from work. If you work in an environment where you are exposed to contaminants such as dust, dirt, or chemicals, you may plan to take a few weeks off.
  • The surgeon will follow up with you over several visits. If they find your eye pressure is still high, they can adjust or remove your sutures to allow more fluid out of the eye.

Success Rates of Trabeculectomies

Generally, trabeculectomies have a reasonably high success rate. A successful procedure means the eye pressure stays normal without additional treatments or medication.

Studies find that, on average, eye pressure drops by about 48% after trabeculectomy. The surgery remains successful for about 86% of patients one year after surgery. After three years, approximately 70% of trabeculectomies are still successful. At five years, that number is closer to 40%. 

Once a trabeculectomy fails, a second trabeculectomy or other glaucoma surgery may be necessary. In other cases, some people must continue their glaucoma medication even after trabeculectomy surgery.

Trabeculectomy Versus Other Glaucoma Surgeries

There are alternative glaucoma surgeries to trabeculectomy, which include:

  • Trabeculoplasty (selective laser trabeculoplasty) is a procedure in which a laser is applied to the tissue in the drainage angle to increase fluid drainage. The laser targets specific cells and leaves the rest of the tissue intact, so it is less invasive than other lasers that treat glaucoma. The results may last several years and can be repeated once they wear off. However, trabeculoplasty may not be as effective as trabeculectomy in some people with extremely high intraocular pressure.
  • Iridotomy is often performed on people who are at risk for angle-closure glaucoma, a type of glaucoma that can cause the eye pressure to shoot up quickly and results in permanent damage if left untreated. During an iridotomy, the surgeon uses a laser to create a small hole in the iris, the colored part of the eye. This allows aqueous fluid to flow out through the opening. Some studies find that trabeculectomy is more effective than iridotomy at lowering eye pressure.
  • Cyclophotocoagulation is a laser procedure that is often reserved for complex or advanced cases of glaucoma. However, modern techniques of cyclophotocoagulation are less destructive to the tissue, allowing surgeons to use this treatment on patients with early glaucoma. Cyclophotocoagulation may be an alternative for people who are not candidates for glaucoma surgery, including trabeculectomy.
  • Tube shunts are drainage devices that are surgically implanted in the eye. They are small, plastic tubes that direct aqueous fluid from inside the eye into a small reservoir. From there, your body can absorb the excess fluid. Typically, the surgeon uses tube shunts when a trabeculectomy surgery fails.
  • Minimally invasive glaucoma surgeries (MIGS) are newer glaucoma treatments that are less invasive and allow faster healing time. There are different types of MIGS procedures, but many involve implanting a small device called a stent, which increases the amount of fluid leaving the eye. Sometimes this procedure is combined with cataract surgery. Although MIGS surgeries are generally safer and carry a lower risk for complications, trabeculectomy is more effective in advanced glaucoma cases.

Author: Melody Huang, O.D. | UPDATED July 15, 2020
Resources

Chen, Yan Yun, et al. “Laser Peripheral Iridotomy versus Trabeculectomy as an Initial Treatment for Primary Angle-Closure Glaucoma.” Journal of Ophthalmology, vol. 2017, Sept. 2017, pp. 1–6., doi:10.1155/2017/2761301.

Gedde, Steven J., et al. “Three-Year Follow-up of the Tube Versus Trabeculectomy Study.” American Journal of Ophthalmology, vol. 148, no. 5, Nov. 2009, pp. 670–684., doi:10.1016/j.ajo.2009.06.018.

Gupta, Viney, et al. “Lasers in Glaucoma.” Indian Journal of Ophthalmology, vol. 66, no. 11, Oct. 2018, pp. 1539–1553., doi:10.4103/ijo.ijo_555_18.

Manasses, Demetrios T., and Leon Au. “The New Era of Glaucoma Micro-Stent Surgery.” Ophthalmology and Therapy, vol. 5, no. 2, June 2016, pp. 135–146., doi:10.1007/s40123-016-0054-6.

Nouri-Mahdavi, Kouros, et al. “Outcomes of Trabeculectomy for Primary Open-Angle Glaucoma.” Ophthalmology, vol. 102, no. 12, Dec. 1995, pp. 1760–1769., doi:10.1016/s0161-6420(95)30796-8.

Piltz-Seymour, Jody, et al. “Trabeculectomy.” EyeWiki, 26 Oct. 2015, eyewiki.aao.org/Trabeculectomy.

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