(1)
Newcastle Eye Centre Royal Victoria Infirmary, Newcastle upon Tyne, UK
Electronic Supplementary Material
The online version of this chapter (doi:10.1007/978-3-319-59924-3_12) contains supplementary material, which is available to authorized users.
The technique of ‘groove-and-crack’, coupled with the ability to debulk large fragments, is a useful method for tackling the majority of cataracts. However, as training progresses, surgeons may wish to develop the nucleus chopping method of creating fragments. A chop technique requires the phaco tip to be embedded the into the lens nucleus whilst the second instrument cleaves the lens nucleus apart. The original chop [1] has been adapted and refined into two chopping techniques, vertical and horizontal [2]. The vertical and horizontal phaco chop are advanced techniques, best attempted once Trainee surgeons have become highly skilled in standard methods.
This chapter describes a variant of stop and chop [3] and phaco quick chop [4]. Skills previously gained in the modules of grooving, cracking and debulking can be utilised. Using this technique, Trainees can tackle moderately dense cataracts and keep the overall phacoemulsification time as short as possible without the need to place the chopper instrument under the capsulorhexis and out to the equator of the lens.
The technique is relatively simple to perform but requires additional bimanual skills. It assumes that the surgeon can perform the grooving-and-cracking technique, debulk large fragments, and remove them using well-controlled phacoemulsification. Once phaco and second-instrument control have been developed, the technique can be taught in a step-by-step manner. It may even be possible to do this quite early on in training, as part of modular nucleus disassembly training, before or after corneal incision training.
If initial attempts at using the chop technique are unsuccessful, it is possible to revert to a standard grooving-and-cracking technique as a means of completing lens separation. Additional attempts can subsequently be made after the lens has been rotated.
As in previous chapters, it is advisable to read the whole chapter in order to gain a clear understanding of the technique. Trainer teaching pearls are at the end of the chapter.
12.1 Fundamentals
Three fundamental principles need to be understood (Fig. 12.1a–d):
Fig. 12.1
Fundamental chop technique. (a) Side profile of embedded phaco tip. The probe is embedded below the surface (star) of the lens into nucleus in an oblique direction (arrow). (b) Microscope view of embedded phaco tip. Phaco tip is buried directly into lens (arrow). (c) Whole of chopper tip is inserted vertically into lens substance just distal and to the left-hand side of the phaco tip. (d) Cleavage. The instruments are pulled apart laterally (arrows) and the lens nucleus spilt
- 1.
The technique requires the application of phacoemulsification in order to bury the phaco tip into a solid part of the lens nucleus. There is no requirement to try and extract the lens from the bag before the chop—indeed this should be avoided. Phacoemulsification is turned off after the phaco tip is buried into the lens. The amount of aspiration is kept to a minimum or also turned off. The phaco tip will maintain its hold on the nucleus unless the probe is pulled backwards by the surgeon.
- 2.
The lens nucleus is impaled by the second instrument tip (any suitable chopper). The chopper tip needs to be inserted just distal to the phaco tip, ideally to the left of midline (but well inside the rhexis margin to avoid a capsule tear).
- 3.
The two instruments are separated laterally (as if performing a standard crack) with the phaco moving to the right and the second instrument to the left. Cleavage will result, with the lens nucleus split into two halves. If required, a reverse-crack, using a cross-over technique can also be applied to ensure adequate separation of the lens pieces.
12.2 Step-by-Step Approach
A key component of chopping is maintaining the phaco tip in a steady position whilst the chopper impales the lens nucleus. Novice surgeons often try to pull the lens centrally into the safe zone. This occurs because there is a perception that the chopper needs to be placed away from the phaco tip; or that the chopper should be kept peripheral to the lens equator, under the capsulorhexis. This is not required for this chop technique. Movements are all performed within the boundaries of the capsulorhexis.
12.3 Step-by-Step Training
The technique can be learnt in steps and attempted at convenient, suitable moments during surgery.
12.3.1 Pre-Cracking Training
The novice surgeon should perform a slightly altered groove-and-crack technique. During sculpting, there comes a point when a final groove is required for correct trench depth. This last groove should be performed in the standard fashion, but at the end of the stroke the phaco probe should be held and maintained in the distal aspect of the groove. The phaco should not pulled back to verify the trench depth and a minor rotation before cracking is not performed. The chopper is then inserted into the groove, adjacent to the phaco tip, and the nucleus cracked. Once the surgeon is able to hold the phaco probe steady and place the chopper tip into the groove step 2 can be attempted.
If cracking is unsuccessful, novice surgeons should resort to a standard grooving-and-cracking technique to complete lens separation. After the lens has been rotated further grooving is preformed and the phaco kept in the groove on the last stroke and a cracking attempt can once again be attempted.
12.3.2 Initial Chop Attempt After the Initial Trench is Formed
A grooved trench should be created, with the groove stroke commencing at the starting point adjacent to the capsulorhexis near the corneal incision. The groove required for a chop attempt needs to be short and deep (i.e. novices should “go for depth” not length) (Fig. 12.2a). Instead of trying to crack and divide the trench in a standard fashion, the phaco tip is first embedded at an oblique angle into the distal part of the trench wall. This is performed below the superficial epinucleus, grooving directly into a solid part of the nucleus (Fig. 12.2b). A J-shape upward movement should not be performed. Phaco application should be stopped once the tip is embedded. A tongue of lens material will be held within the mouth of the phaco tip, and as long as the phaco is not pulled backwards the tip will remain embedded in the lens nucleus.
