The pre-chopper was popularized by Prof Akahoshi from Japan and it was designed to mechanically chop the nucleus into quadrants before placing the phaco probe in the eye. In other words, the nucleus is pre-chopped before the fragments are phaco-aspirated. However the same instrument can also be used to split a nucleus once a groove has been sculpted and that is the technique shown here. If you are struggling to learn phaco chop, then perhaps you should give the pre-chopper a try. It can make surgery easier and more efficient compared to standard divide and conquer.