Divide and conquer is a popular technique of nucleus removal during cataract surgery and it is usually the first technique learned by beginning ophthalmologists. There are some potential advantages with divide and conquer, the most important of which is the removal of time as a limiting factor. During phaco chop, once the phaco probe is embedded into the nucleus, there is a small window of time, perhaps 1 or 2 seconds, during which the chop must be accomplished. If we wait too long, then the vacuum will drop and the holding power of the nucleus will be diminished. With divide and conquer, there is no similar time limitation and we can take as long as we need to split the nucleus into smaller pieces.
Another advantage is that the grooves that are created in the nucleus also serve to debulk it. If we chop a nucleus into four quadrants, then each one will be about 25% of the total volume (4 x 25% = 100%). When we create grooves in divide and conquer, we are removing nuclear material so that each quadrant will end up being about 20% of the total volume (4 x 20% = 80% of the volume since the other 20% was removed while sculpting the grooves). These smaller nuclear pieces can be easier to manipulate and control for beginning surgeons who are learning to operate in the confines of the anterior segment.
The downside of divide-and-conquer is that it is less efficient and more ultrasonic energy is used when compared to phaco chop. You can split a nucleus into quadrants using phaco chop and 1 second of ultrasound energy. To accomplish the same 4 way split using divide and conquer will require many times as much energy. In fact, very frequently more ultrasonic energy will be used to create the grooves than will be needed to remove the quadrants.
Be sure to master the divide and conquer technique during your residency training. Then you can continue learning other techniques like stop-and-chop and then finally the variations of phaco chop. Remember that the best surgeons continue to learn and advance their skills throughout their decades long careers.