postoperative course of isolated cataract surgery signiÞcantly. The extraction of the cataract makes it possible to increase the iridocorneal angle and facilitates the placement of the implants.

8.4.2 Anesthesia

In the case of phakic patients, the instillation of a miotic is recommended to minimize the risk of lens injury. If the procedure is carried out under topical anesthesia it is advisable to introduce lidocaine 1% into the anterior chamber, as some of the surgical maneuvers can be uncomfortable for the patient. It is perfectly possible to carry out the surgery under topical anesthesia with intracameral lidocaine; however, when performing the operation for the Þrst few times, it may be advisable to use some form of locoregional anaesthetic (retrobulbar, peribulbar, or sub-Tenon).

8.4.3 Surgical Technique

The trabecular stent can be implanted by means of the same incision used for phacoemulsiÞcation in cases of combined surgery, or by means of a 1.5 mm incision, when the stent is implanted as an isolated operation. In any case, the corneal incision should be temporal in order to be able to implant the stent in the nasal region of the trabecular meshwork, where the number of collecting channels is greatest.

8.4.3.1 Preparation

Once the incision has been made in the temporal cornea, the anterior chamber must be Þlled with a cohesive viscoelastic that makes it possible to enlarge the region of the angle where the stent is to be implanted.

To perform this surgery, a perfect view of the trabecular meshwork must be achieved. The most common error when performing the operation for the Þrst few times is failure to position the microscope and/or the patient properly to obtain an adequate view of the trabeculum. The patientÕs head must be inclined some 45¡ to the side opposite the eye to be operated on. For example, if we are operating on the right eye we will

ask the patient to turn his/her head to the left. Moreover, the microscope should be tilted by approximately 30¡, as when performing a goniotomy. We check whether the position is correct by using the goniolens (Fig. 8.50).

Next, the applicator corresponding to the eye to be operated on must be selected, as there are implants for the right eye and implants for the left eye. The difference lies in the orientation of the bevel, designed to facilitate the penetration of the implant into the trabecular meshwork. The distal tip of the implant always should always point toward the patientÕs feet at all times.

8.4.3.2 Implantation of the Micro-Bypass Stent

The tip of the stent should approach the trabecular meshwork at an angle of 15¡ to facilitate penetration of the tissue. Excessive resistance indicates a path that is too perpendicular to the trabeculum. Once the trabecular meshwork covers all of the implant, it should be released by pressing the applicator button. Only the proximal end of the stent should remain visible in the anterior chamber. The stent can be seated in its Þnal position by gently tapping the side of the snorkel with the inserter tip. The stent should be placed parallel to the plane of the iris with the inner part covered by the meshwork and the lumen away from the iris (Fig. 8.51). A small reßux of blood from the SchlemmÕs canal is common and reßects proper positioning of the stent.

Surgery concludes with the extraction of the viscoelastic material and the hydration of the corneal incision.

Fig. 8.51 Gonioscopic view of the Glaukos¨ iStent¨ inserted in the trabecular meshwork