a phacoemulsification system includes a platform controlling the phacoemulsification process and a handpiece attached to the platform and used by a surgeon to perform an operation . the handpiece includes a hollow phaco needle with a flexible sleeve around the needle and provides an infusion fluid sourced at the platform into the eye . the sleeve , which may be disposable , is provided with a sensor device configured to sense the instantaneous fluid pressure in the eye during the operation and send this information to the platform . this information is used by the process to control the pressure of the infusion fluid to insure that the eye is not injured and to otherwise protect the eye during the operation .