GLAUCOMA SURGERY

Most glaucoma patients can be successfully treated with SLT laser and drops. When those treatments are inadequate, the next step is usually a procedure to make the front drain of the eye function better.

Schlemm’s canal procedures: The front drain has a circular channel (Schlemm’s canal) like a hula hoop, just in front of the iris. The canal’s inner wall (trabecular meshwork) can be opened from the inside (goniotomy). There are several variations of these goniotomy procedures, but they all make it easier for the eye fluid (aqueous humor) to enter the canal and leave the eye. Alternatively, a tiny metal stent (Hydrus or iStent) can be used to prop open the trabecular meshwork.

The procedures described above work most reliably for patients with a pressure that is just a little too high despite using several medications. Typically, the patient’s cataract has also become cloudy enough to require a lens replacement, and the surgeon recommends improving the natural drain of the eye at the same time. However, patients with advanced damage and a pressure more than 20 are often better treated by creating a new artificial drain.

Procedures which create a new drain: Trabeculectomy surgery entails cutting an opening into the eye, creating a new drain for aqueous humor to flow out into a pocket between the sclera and conjunctiva. XEN stent is a variation of this concept: a tiny drain tube connects the inside of the eye to the external space between the sclera and conjunctiva. Scarring sometimes closes the space between the sclera and conjunctiva so fluid can no longer leave the eye. Another option is a tube connected to a soft piece of plastic about the size of a dime that helps prevent the conjunctiva from scarring down to the sclera; Ahmed tubes are a common example. Over the past decade, tube surgeries have become more popular than trabeculectomies because they seem less prone to complications and failure (though the data vary depending on who does the surgery). XEN stents are believed by some to have fewer complications than tubes or trabeculectomies, but they may also be more prone to failure by scarring.