12 Phaco Prechop Procedure The phaco prechop procedure is a very effective way to dismantle the nucleus prior to removal. Prechopping is utilized to achieve a split of the nucleus within the capsular bag without the use of phacoemulsification energy. Takayuki Akahoshi1 first introduced this technique in 1993, and he has been instrumental in pioneering the prechop technique and in developing instrumentation for it. Several variations of the prechopper instrument are available. The prechopper is a cross-action forceps, and most are designed with a sharper-edged blade on one side and a rounded or blunted edge on the back. The rounded edge can be used to divide a softer nucleus, or to finish the split after the sharper edge has been employed (Fig. 12.1). Prechopping provides the benefit of nucleus division without ultrasound energy or fluid. This technique is ideal for moderate nucleus densities (grades 2 and 3). To perform prechopping safely, thorough hydrodissection is imperative. In addition to hydrodissection (Fig. 12.2), hydrodelineation should be performed to improve safety and assist with nucleus quadrant removal. Hydrodelineation is accomplished by injecting fluid at the midperipheral nucleus to separate the epinuclear and endonuclear layers (Fig. 12.3). Hydrodelineation provides an additional cushion of protection prior to dividing the nucleus with the prechopper (Fig. 12.4). Following hydrodissection and hydrodelineation, the surgeon should inject a dispersive viscoelastic agent to blow away the loose cortical material and provide a well-pressurized anterior chamber. This is essential. A cohesive viscoelastic is not ideal, as it can be inadvertently expressed out of the wound with the introduction of the prechopper. This will cause a loss of anterior chamber pressure, which significantly reduces the effectiveness of the prechop maneuver. The technique for successful application of the prechopper involves placing the sharp end of the blades ∼ 1 mm to the distal side of the center nucleus and applying gently downward pressure (Fig. 12.5). Once the nucleus is entered (to ∼ 1½ mm depth or half the depth of the nucleus), the cross-action prechopper is then opened to achieve a split (Fig. 12.6). Maintaining the prechopper in the open position for a few seconds helps to effectuate the split across the nucleus. If the nucleus does not fully split, the instrument is placed in the same groove, slightly more posterior, and the maneuver is repeated. This should complete the split. The nucleus should then be rotated 90 degrees using the prechopper blades in the closed position. The prechopper is again placed slightly distal to the central nucleus to divide the distal hemi-nucleus). This placement often achieves a split of both hemi-nuclei; if not, the instrument is moved proximally and the maneuver repeated to split the proximal hemi-nucleus (Fig. 12.7). Once the prechop has been accomplished, the surgeon performs phacoemulsification using nucleus quadrant removal settings. A second instrument can be utilized; however, phacoemulsification is often easily performed using a single-handed technique, particularly if the nucleus quadrants are already nicely delineated and divided. Cataracts of grades 2 and 3 are optimal for prechopping. Prechopping the nucleus is a good technique to apply when pupil dilation is limited, as it obviates the need for grooving with phacoemulsification when visualization is compromised. It is also a good technique for the patient with a compromised endothelium, as it will significantly reduce phaco energy and the amount of fluid used.
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