The phaco probe angle changes during the procedure. When we embed the phaco tip into the nucleus, the probe is at a steeper angle of 30 degrees or more. We are aiming the phaco probe tip towards the optic nerve when sitting temporally. Once the phaco chop has been propagated and the nucleus has been separated into smaller fragments, the phaco probe angle decreases to about 10 degrees. The phaco tip emulsifies the nuclear fragments at about the iris plane which means that the phaco probe is nearly parallel to the iris.
click below to learn the different phaco probe angles required for phaco chop: