The suction method for intracapsular cataract extraction is nowadays far less popular than the forceps method. However, a comparative study of the grasping mechanism with forceps and with the vacuum cup clearly demonstrates the superiority of the latter. In fact, the forceps "pinches" a small piece of the delicate capsule, from which the lens will hang loosely. As Thomas1 has stated: "The entire weight of the lens and its attachments are suspended from a relatively small area." The mechanism of the grasp with a vacuum cup is quite different. When atmospheric pressure between the cup and the lens drops, the air pushes the lens against the cup, to which it adheres. Dimitry2 has expressed this in terms physically exact when stating, "The atmospheric pressure, seeking to balance the vacuum, forces the lens into the cup."
The advantages of this grasp are the following: 1. There is no pinching
VILLASECA A. New Mercury Vacuum Pump and System of Slowly Applied Vacuum for Phakoerisis. AMA Arch Ophthalmol. 1956;55(1):9-20. doi:10.1001/archopht.1956.00930030011003