Hydro-delineation can be helpful to separate the dense endo-nucleus from the epi-nucleus of the cataract. This makes is a bit easier to chop and sub-divide the endo-nucleus while maintaining a protective epi-nucleus over the posterior capsule. After removing the endo-nucleus, it can become a challenge to remove the bowl-shaped epi-nucleus.
The key for me is to flip up the epi-nucleus using a two-handed approach with the phaco probe on vacuum mode only (no ultrasound power) to grasp an edge of the epi-nucleus while the outer curve of chopper used to push the nucleus forward and then up.
click below to watch the video to learn this important technique: