This feature is especially important if your surgeons use the newer chopping technique, because they often like to use high vacuum to hold the nucleus while chopping with the second instrument. Once the nucleus is in pieces and the surgeon is ready to remove them, another new fluidics feature comes into play. During this phase, it can be helpful to use high vacuum, since you want the pieces of the lens to come to the mouth of the phaco needle. However, this can be dangerous with an older machine, because when a piece of lens material occludes the tip and vacuum builds and then breaks suddenly when the piece is sucked in, a large amount of fluid can be sucked in as well. Simple physics cause the anterior chamber to then collapse, bringing either the delicate corneal endothelium or the fragile posterior capsule dangerously close to the phaco tip.
Endothelial compromise can lead to corneal transplant.
Capsular rupture is a precursor to several sight-threatening complications, including CME and even endophthalmitis. Many of the newer machines use multiple devices that help prevent this problem by keeping a good balance between the amount of fluid and material exiting the eye and the amount entering the eye. Besides fluidics, some of the newer machines also allow surgeons to titrate phaco power more. Old machines allowed only a linear application of power, but some of the new ones allow the surgeon to apply power in short bursts. This can be useful when performing delicate tasks.