The bimanual technique still has a role to play even if it is now possible to perform a coaxial phaco through a microtunnel
One pioneer of this new technique referred to it as "sayonara bimanual,"11 meaning that if it is possible to perform the operation with a coaxial handpiece through a microincision then the bimanual procedure is no longer required.
On a quest to find the answer
First, we'll consider fluidics. During coaxial phaco a portion of the irrigation flow is captured by the phaco-tip immediately after flowing out from the sleeve, and by having the irrigation flow near the aspiration, nuclear fragments can be pushed away.
With irrigation on one hand and aspiration on the other both followability and holdability can be increased. So, settings for coaxial and bimanual surgery are a little different. In fact, slightly decreased aspiration and vacuum rates can be used with bimanual surgery compared with coaxial phaco.
It is also important to note that by separating irrigation from aspiration we can use irrigation like a surgical tool. This is one of the most important reasons why open-ended irrigating choppers have come back into fashion. Furthermore, a chopper with lateral openings of the same diameter and irrigating area leads to lower irrigation.