The needles are inserted along the grooves within the wings so that they enter the scleral wall at a position 2 mm from the corneal limbus. The 2 scleral tunnels are made with an angle of 20 degrees tangential to the corneal limbus and 10 degrees in relation to the iris plane (Figure 71-3).
When using the Yamane needle stabilizer, both 30-gauge guide needles are placed into the eye prior to then injecting the IOL into the eye and threading the 2 haptics into the guide needles. The first step is marking the double-needle entry points. The 2 dents on the inner edge of the ring are in line with the 2 insertion point visual marks. Use these dents to place reference marks (Figure 71-4) and to align the ring inside diameter with the corneal limbus. Next, a 30-gauge thin-walled needle is advanced along the groove of the needle stabilizer wing (Figure 71-5) without penetrating the sclera. After the intraocular pressure is raised to at least 30 mm Hg, the stabilizer instrument is pressed firmly against the globe to ensure proper fixation. The 30-gauge thin-walled needle is advanced along the groove until it contacts and penetrates the scleral surface at the location of the needle insertion point marker (Figure 71-6). It is then advanced further along the needle stabilizer groove in the same direction, so that it creates a 2-mm intrascleral tunnel before perforating through the pars plicata (Figure 71-7). If the 30-gauge thin-walled needle is bent 7 mm from the tip, it will stop when the needle has advanced 3 mm into and through the sclera. Once the tip has perforated into the eye, the needle shaft is removed from the groove (Figure 71-8). It is redirected perpendicular to the limbus and advanced radially until its tip is confirmed to be in the eye through the pupil (Figure 71-9). A second 30-gauge thin-walled needle is inserted in the same manner on the contralateral side. As soon as both needles have been removed from their respective grooves and their tips are visualized within the pupil, the needle stabilizer is removed and the surgery continues as previously explained in this book.