Last updated: 02/17/2009

Before the surgeon begins the procedure, the patient is given miotics, which are drugs that cause the pupil to contract. This partial closure improves the surgeon's view of and access to the trabecular meshwork; it also protects the lens of the eye...

from trauma during surgery. Other drugs are administered to lower the intraocular pressure.

Once the necessary drugs have been given and the patient is anesthetized, the surgeon uses a forceps or sutures to stabilize the eye in the correct position. The patient's head is rotated away from the surgeon so that the interior structures of the eye are more easily seen. Next, with either a knife-needle or a goniotomy knife, the surgeon punctures the cornea while looking at the interior of the eye through a microscope or a loupe. An assistant uses a syringe to introduce fluid into the eye's anterior chamber through a viscoelastic tube as the surgeon performs the goniotomy.

A gonioscopy lens is then placed on the eye. As the eye is rotated by an assistant, the surgeon sweeps the knife blade or needle through 90–120 degrees of arc in the eye, making incisions in the anterior trabecular meshwork, avoiding the posterior part of the trabecular meshwork in order to decrease the risk of damage to the iris and lens.

Once the knife and tubing are removed, saline solution is introduced through the hole to maintain the integrity of the eye and the hole is closed with sutures. The surgeon then applies antibiotics and corticosteroids to the eye to prevent infection and reduce inflammation. The head is then rotated away from the incision site so that blood cannot accumulate. The second eye may be operated on at the same time. If the procedure needs to be repeated, another area of the eye is treated.