When eye drops, pills, laser surgery, or other less invasive glaucoma surgeries (MIGS) fail to adequately control your eye pressure, your doctor may recommend a more aggressive filtration surgery called a trabeculectomy. This operation works by bypassing the traditional outflow pathway or drain and creating a new drainage pathway using the natural tissues of the eye. 

During the operation, the superficial tissue of the eye (conjunctiva) is opened, a flap is created in the underlying thicker tissue (sclera), and a pathway or tunnel is created into the eye by removing a portion of the trabecular meshwork (drain of the eye). The flap is then sutured down to titrate the amount of outflow and the conjunctiva is then closed. This allows fluid in the eye to more readily drain through the created outflow pathway, under the flap, and into a reservoir underneath the conjunctiva (filtering bleb). It is then reabsorbed back into the body, ultimately resulting in lower eye pressure.

The human body reacts to eye surgery as an injury, so its tendency is to scar down or wall of this newly created outflow channel. The surgeon will use anti-scar medication during the procedure, usually mitomycin-C (MMC) or occasionally 5-fluorouracil (5-FU). You will also use steroid eye drops following the surgery to help maintain the patency of the trabeculectomy. 

The trabeculectomy is done in an ambulatory surgery center under light intravenous sedation (like cataract surgery) and usually a local eye block.  Following this procedure, your eye is generally covered with a patch and removed the next day at your appointment. You will then be using post-operative medications but initially will be off of your glaucoma drops. Following the initial appointment the day after your surgery, your surgeon will examine you weekly for the first couple of weeks. It is important to monitor these surgeries carefully in the initial postoperative period as adjustments can be made for pressures that are too low or too high. If the pressure is too high, it is usually because there is not enough fluid outflow through the tunnel underneath the scleral flap. This flap or valve can be loosened by cutting a stitch in the office using a painless laser, allowing increased fluid outflow, and lowering your eye pressure.