Trabeculectomy

The eye constantly makes a clear fluid called aqueous humor that nourishes the front of the eye. The fluid normally drains out through the trabecular meshwork in the angle of the eye. In glaucoma, this drain is partially blocked. Pressure rises and the optic nerve is slowly damaged.

Trabeculectomy creates an entirely new drain.

The surgical steps:

• The surgeon lifts a small flap of conjunctiva (the clear surface of the eye) at the top of the eye, under the upper eyelid.
• A small dose of mitomycin C (an anti-scarring medicine) is applied for about 1-3 minutes, then rinsed off. This medicine stops scar tissue from closing the new drain.
• The surgeon cuts a partial-thickness flap in the sclera (the white of the eye), about 4 mm wide.
• Underneath this scleral flap, a small block of tissue is removed, opening a window from the inside of the eye to the space under the conjunctiva.
• The scleral flap is closed loosely with a few stitches — some of which can be removed at the slit-lamp later to control flow.
• The conjunctiva is closed water-tight on top.

The result is a small fluid-filled pool — the bleb — under the upper eyelid. The bleb cannot be felt and is not visible unless you lift the lid. Fluid leaves the eye into the bleb at a slow, controlled rate, and from the bleb is absorbed into the body. This is why trabeculectomy is also called a filtering surgery.

Trabeculectomy is most often offered for:

• Moderate to advanced open-angle glaucoma not controlled by maximum tolerated medical therapy and laser.
• Normal-tension glaucoma when target pressure has not been reached by drops or laser.
• Pseudoexfoliation and pigment dispersion glaucoma with high or unstable pressure.
• Some types of secondary glaucoma, including steroid-induced glaucoma.
• Patients who cannot tolerate or use glaucoma drops reliably.

Trabeculectomy is usually NOT first choice for:

• Patients with significant conjunctival scarring from previous surgeries — a tube shunt is often better.
• Neovascular glaucoma or aphakic eyes — tube shunts usually do better.
• Patients who cannot reliably attend many follow-up visits during the first 3 months.
• Patients with active uveitis or untreated infection of the surface of the eye.

The choice between trabeculectomy and a tube shunt has been studied directly in two large randomized trials — the Tube Versus Trabeculectomy study (in eyes with prior intraocular surgery) and the Primary Tube Versus Trabeculectomy study (in eyes without prior intraocular surgery). Updated meta-analyses comparing tube shunt implantation and trabeculectomy continue to refine these recommendations ³.

Before surgery:

• You meet with the glaucoma specialist who will perform the operation. They check your pressure, optic nerve, visual field, and the surface of the eye.
• You may be asked to taper certain glaucoma drops or stop blood thinners depending on the surgeon's preference and your medical history.
• You arrange a ride home and someone to help with daily tasks for the first day or two.

During surgery (45-90 minutes):

• The eye is numbed with an injection around the eye. You may also have IV sedation to relax you.
• You stay awake but feel only pressure, not sharp pain.
• The surgeon places the scleral flap, the small drainage window, the mitomycin, and the closing sutures.
• A clear shield is placed over the eye for the trip home.

After surgery:

• Drops: antibiotic and steroid drops several times a day, slowly tapered over weeks. Your glaucoma drops in the operated eye are usually stopped.
• Activity restrictions: avoid heavy lifting, bending below the waist, swimming, hot tubs, and rubbing the eye for 2-4 weeks. Walking, light housework, screens, and reading are usually fine.
• Wear the shield at night for about a week to keep from rubbing the eye in your sleep.
• Frequent follow-up: often weekly for the first month, with adjustments — releasing sutures, injecting medications around the bleb to discourage scarring, or fine-tuning drops.

Trabeculectomy lowers eye pressure more than any other commonly used glaucoma surgery, but it has more complications than MIGS procedures. Most are managed and most settle, but they are why frequent early follow-up matters.

• Too-low eye pressure (hypotony). The eye's structures depend on a steady pressure. Persistently low pressure can cause shallow anterior chamber, choroidal effusion, and a corneal change called hypotony keratopathy that can blur vision and even damage the cornea long term ⁷.
• Bleb-related infection (blebitis or bleb-associated endophthalmitis). A late, vision-threatening infection of the bleb or inside of the eye, sometimes years after surgery. Risk factors include thin avascular blebs, inferior blebs, mitomycin use, and bleb leaks ⁸.
• Bleb leak. The thin tissue over the bleb can leak fluid, causing low pressure or letting bacteria in. May need a small revision.
• Cataract progression. Cataracts almost always develop or speed up after trabeculectomy in adults over 50. Many patients eventually need cataract surgery — a known long-standing relationship between cataract and glaucoma surgery ⁹.
• Bleb encapsulation or scarring. The body sometimes wraps the bleb in scar tissue, which raises the pressure again. May need office injections, suture lysis, needling, or revision surgery.
• Astigmatism and refractive change. Common in the first months and usually settles.
• Failure of the surgery. Even with mitomycin C, some trabeculectomies fail over time. Failure is more likely in younger patients, neovascular glaucoma, and eyes with prior intraocular surgery ⁶.
• Newer alternatives. The PreserFlo MicroShunt is a newer bleb-forming device that aims for a simpler, more predictable operation than trabeculectomy. An updated meta-analysis comparing PreserFlo MicroShunt versus trabeculectomy found trabeculectomy still produces somewhat lower eye pressures, while the MicroShunt has fewer postoperative interventions and a comparable safety profile ¹⁰.

What trabeculectomy costs in the U.S.:

• Trabeculectomy with mitomycin C: about $3,000-$6,000 per eye, including the surgeon's fee, the surgery center fee, and anesthesia.
• Follow-up visits and drops are usually billed separately and add several hundred dollars over the first 3 months.

What insurance usually covers:

• Medicare and most U.S. health insurance plans cover trabeculectomy when an eye doctor documents glaucoma that has not been controlled by drops or laser, or when there is clear progression of the optic nerve or visual field.
• Follow-up visits, suture lysis, and bleb-related procedures (needling, anti-scarring injections) in the first 3 months are usually included in the global surgery package — most patients pay only their normal copay or coinsurance.
• If glaucoma surgery is needed in both eyes, they are usually scheduled separately, and you pay your deductible and coinsurance for each eye.

Out-of-pocket costs:

• Most patients pay their usual deductible, copay, and coinsurance.
• If you are uninsured, the cash price for trabeculectomy varies widely; ask the surgery office for a written self-pay estimate.