A trabeculectomy is a common surgical procedure to manage the pressure inside the eye. It is a type of filtering surgery that creates a new drainage system for the eye’s internal fluid. This procedure is recommended when other treatments, such as eye drops or laser therapy, have not been successful in controlling the pressure. The ultimate goal is to prevent further damage to the optic nerve.
The Goal: Why Trabeculectomy is Necessary
The need for a trabeculectomy arises from glaucoma, a condition associated with elevated Intraocular Pressure (IOP). Inside the eye, aqueous humor is constantly produced and drained to maintain the eye’s shape and health. When the eye’s natural drainage system, the trabecular meshwork, becomes blocked or inefficient, the fluid backs up, causing a buildup of pressure.
This excessive IOP can damage the optic nerve, leading to irreversible vision loss. A trabeculectomy creates an alternative, controlled pathway for the aqueous humor to exit the eye. The surgeon bypasses the clogged natural drain to establish a new route for fluid outflow.
The new drainage site allows the aqueous humor to collect in a small, external pocket created under the conjunctiva. This pocket, known as a filtering bleb, is where the fluid is slowly absorbed back into the body’s circulation. The bleb acts as the new pressure-regulating mechanism.
The Surgical Process Explained
Trabeculectomy is typically performed on an outpatient basis, taking about an hour to complete. The patient receives local anesthesia to numb the eye area, sometimes with additional medication for relaxation. The surgeon begins by creating a partial-thickness flap in the sclera, the white outer wall of the eye.
Next, a small opening is created beneath this scleral flap to access the anterior chamber. This opening, called a sclerostomy, removes a portion of the eye’s internal drainage tissue, the trabecular meshwork. In many cases, a small piece of the iris is also removed (a peripheral iridectomy) to ensure the new pathway remains open.
To prevent the new drainage pathway from closing, the surgeon applies antimetabolites to the surgical site. These anti-scarring medications, such as Mitomycin C or 5-Fluorouracil, inhibit the formation of scar tissue that could block fluid flow. The surgeon then loosely stitches the scleral flap back into place, which acts like a valve to regulate the rate of fluid drainage. The conjunctiva is closed over the site, allowing the aqueous humor to collect and form the filtering bleb.
Immediate Post-Operative Care
The first few weeks after a trabeculectomy are crucial for the success of the new drainage system. Patients are sent home the same day with a protective eye shield, which must be worn at night for several weeks. It is common for the eye to feel irritated, uncomfortable, or blurry as it adjusts to the new pressure level.
A regimen of medicated eye drops is prescribed, including antibiotics to prevent infection and steroid drops to manage inflammation and control scarring. These drops are important for ensuring the filtering bleb functions correctly. Patients must use these drops exactly as instructed, sometimes as frequently as every one to two waking hours during the initial recovery phase.
Activity restrictions prevent a sudden increase in eye pressure that could damage the delicate new bleb. Patients must avoid strenuous activities, heavy lifting, or bending over at the waist for a period of weeks. Follow-up appointments are frequent, often starting the day after surgery, to monitor the pressure and the bleb’s appearance.
Long-Term Outcomes and Potential Risks
Trabeculectomy is effective for controlling IOP. Long-term success rates for maintaining pressure control are high, often cited in the range of 60% to 80% at five years after the procedure. For many patients, the surgery allows them to reduce or completely stop using glaucoma medications.
The most common long-term risk is failure due to excessive scarring, which can cause the filtering bleb to close off. If this occurs, eye pressure may rise again, sometimes requiring a minor procedure to revise the bleb or a repeat surgery. Another risk is the acceleration of cataract formation, where the eye’s natural lens becomes cloudy.
A serious potential complication, though rare, is a long-term infection of the filtering bleb, which can occur months or years after the surgery. Other possible issues include the eye pressure dropping too low, a condition called hypotony, which may lead to blurry vision and require further intervention.