D. Brian Kim, MD
The Yamane double-needle technique is an elegant approach to intraocular lens (IOL) fixation in the absence of adequate capsular support.1,2 It offers efficient scleral IOL fixation without the need for conjunctival or scleral dissection, scleral flaps, glue, or lassoing sutures. Although the procedure looks deceptively easy, it is not without challenges. Internalizing the haptics into the needles is the most challenging step for the learning surgeon because the maneuvers are awkward and unfamiliar, and because the haptics must be guided into tight needle lumens. Risks include but are not limited to haptic damage, IOL slippage into the vitreous space, trauma to intraocular structures, IOL decentration, or IOL tilt.
In general, IOL haptics are made of polymethylmethacrylate (PMMA), polyamide, polypropylene (Prolene; Ethicon), or polyvinylidene fluoride (PVDF). For the purposes of this chapter, haptic material is stratified into 2 groups: more deformable (PMMA, polyamide, polypropylene) vs less deformable (PVDF) haptics. If using an IOL with more deformable haptics, threading the trailing haptic into the docking needle can result in haptic kinking or breakage and ultimately failure of the Yamane technique. In contrast, because PVDF is much more rigid and does not kink or break, it is a much better choice for this technique. However, this same PVDF haptic rigidity tends to resist manipulation, which makes it harder to thread the trailing haptic into the needle. I have developed 2 distinct modifications to the original Yamane technique.
The Method 1 modification includes the following: conjunctival markings to improve IOL position and centration, needle bend and bevel control to improve docking of the haptics, injector-assisted haptic fixation for one-step easy needle fixation of the leading haptic, and optic push to improve access to the trailing haptic for needle fixation. The Method 2 modification is a radical departure from the original Yamane technique because the trailing haptic is fixated before the leading haptic, thus bypassing many of the technical challenges.3 The simplest solution is to externalize the leading haptic out of the eye through an inferior limbal incision. And this is made even easier by using a one-step injector-assisted technique. This maneuver secures the IOL from slipping too far posteriorly into the eye, and because the IOL sits more anteriorly, access to the trailing haptic is enhanced for needle fixation. I believe both of these modifications will greatly improve outcomes, safety, efficiency, and reproducibility for the learning surgeon, as well as offer greater versatility when performing the Yamane technique.
D. Brian Kim Modification Method 1
These modifications will enhance success and minimize difficulty, but before proceeding there are a few important fundamental points. An infusion cannula is essential because a soft globe is difficult to pierce with a needle. An anterior chamber maintainer or pars plana infusion can be used, depending on the surgeon’s experience and preference. I prefer a 23-gauge Lewicky (Katena Products) anterior chamber maintainer.
Every IOL exchange or secondary IOL placement in the absence of capsular support should be preceded by a limited anterior vitrectomy. I prefer a pars plana approach to ensure that the soon-to-be explanted IOL and anterior chamber are free of vitreous before the new IOL is placed. Also, every eye should have a peripheral iridectomy to minimize the risk for pupillary block. I prefer to use the vitrector to perform the peripheral iridectomy. Please see Chapter 64 on Anterior Vitrectomy Pearls for more details.
The type of 3-piece IOL can either frustrate or facilitate one’s ability to perform this technique. Most 3-piece posterior chamber IOLs have haptics that are thin and prone to bending or breakage with manipulation. This technique requires an IOL haptic that can withstand significant manipulation. For a number of reasons, it is my current preference to use the CT Lucia 602 lens (Carl Zeiss Meditec), formerly the Aaris EC-3 PAL (Aaren Scientific) IOL. There may be other viable alternatives available internationally, but in the United States, this is the best choice. This IOL has resilient PVDF haptics that are very durable and resist damage, which makes it well suited for the double-needle technique.
CONJUNCTIVAL MARKING FOR PRECISE NEEDLE PLACEMENT
The following description assumes the surgeon is sitting at the head of the bed and we will call this the superior position. Ink marks are placed at the horizontal limbus while the ocular surface is dry. The 2 and 8 o’clock positions are marked for right eye surgery, while the 4 and 10 o’clock positions are marked for left eye surgery. The marks must be 180 degrees apart and I prefer using an axis ring (Figure 48-1). The 3 and 9 o’clock positions are deliberately avoided to prevent hitting the long ciliary vessels and to enhance surgeon ergonomics. An inked caliper is used to mark the conjunctiva 2 mm posterior to each of these limbal marks (Figure 48-2). For illustrative purposes, these are designated as mark A on the left and mark B on the right. Another mark is placed 2 mm superior to (counterclockwise) mark A and this is mark C (Figure 48-3). Another mark is placed 2 mm inferior to (counterclockwise) mark B and this is mark D. These are the landmarks for scleral needle puncture (see Figure 48-3 and Video 48-1). A 1-mm limbal incision is placed 1 clock hour superior to each of the horizontal marks (Figure 48-4). The anterior chamber is filled with dispersive viscoelastic, and a 3-mm keratome blade is used to create a standard shelved incision superiorly and 90 degrees from the horizontal marks (see Figure 48-4).
BENDING THE NEEDLES: BEVEL CONTROL, LENGTH, AND ANGLE
The CT Lucia 602 haptics do not fit into the lumen of a standard 30-gauge needle. Instead, the 30-gauge 0.5-inch thin-walled needle (TSK Laboratory) is necessary. Although a 27-gauge needle can be used, the haptics do not fit as tightly as within the 30-gauge 0.5-inch thin-walled needle lumen. As a result, the haptic might slip out as a 27-gauge guide needle is externalized through the scleral wall. Moreover, the thicker caliber of a 27-gauge needle creates a larger scleral tract that could be more prone to leakage. Two needles are necessary, one for the surgeon’s left hand and one for the right (Figure 48-5). Using an instrument such as a hemostat, the needle for the surgeon’s left hand is bent in such a way that the bevel faces to the right when the needle hub is upright (see Figure 48-5). This means that once the needle has entered radially through the ciliary sulcus and its tip is visible through the pupil, the bevel will face the 12 o’clock incision (Figure 48-6). I place the bend approximately 8 mm from the tip, which leaves a slight amount of needle between the hub and the bend (see Figure 48-5). The angle can vary according to surgeon preference, but I prefer an angle of approximately 80 degrees. The needle for the right side should be bent at the hub making it as long as possible. Unlike for the left-hand needle, the bevel should face toward the ceiling when the hub of the needle is nearly upright (Figure 48-7). I prefer an 80-degree angle for this second needle bend as well. I prefer mounting the needles onto a 1-cc syringe for improved ergonomic control (Video 48-2). A final pearl with regard to the needles is to fill them with balanced salt solution (BSS). If the needles are not filled with BSS, bubbles will emanate from the needle tips and obscure the view for haptic fixation.
Infusion is activated to maintain a firm globe to facilitate needle passage and placement. Using the conjunctival marks as a guide, the left needle is placed at mark C (Figure 48-8). A cotton-tipped applicator or fixation ring can be used to stabilize the globe to control the needle as it is pierced through the conjunctiva and sclera. The needle is advanced near-parallel to the scleral wall in order to tunnel toward mark A. Care must be taken to avoid premature penetration into the vitreous space. When mark A is reached, the needle is turned near-perpendicular to the globe, and with the needle pointing toward the optic nerve, the sclera is punctured. The needle is rotated clockwise and the tip emerges from underneath the iris and into view with the bevel facing the main incision (see Figure 48-6 and Video 48-3).
Modifications to the Original Technique
INJECTOR-ASSISTED HAPTIC FIXATION
With the left hand continuing to hold the needle, the right hand is used to insert the IOL injector through the superior keratome incision. The surgical assistant begins to advance the IOL by twisting the plunger. As the leading haptic emerges, the barrel of the injector is rotated so that the haptic is pointing leftward and toward the needle. As the technician continues to advance the IOL, the surgeon positions the needle in such a way that the haptic engages the bevel of the needle, which causes it to slide into the lumen (Figure 48-9). As the IOL is advanced, the haptic continues to slide deeper into the needle. Care must be taken to instruct the technician when and how quickly to advance, otherwise the haptic may not slide into the needle effectively. The haptic is advanced until more than half of its length is inside the needle. Once the optic is delivered and unfolds into the anterior chamber, the injector is removed and the trailing haptic is left outside of the eye and pushed to the right in the correct orientation (Figure 48-10). The left-side needle hub is released and laid down. But if the syringe is attached too tightly to the needle, hemostat forceps may be used to help disengage the syringe from the needle hub (Video 48-4). One must carefully avoid sudden, uncontrolled movements of the IOL during this step.