A method and apparatus for precisely controlling particle movement relativeto a phacoemulsification needle tip is provided. The design monitors actualvacuum present and calculates a pulse shape amplitude waveform proportionalto the amount of measured vacuum. An increase in vacuum indicates that the handpiece/needleis becoming occluded by a large particle. The present design determines whetheradditional power is required to bump or move a large particle away from the needletip. The present design may employ a control loop that senses and continuouslymonitors vacuum. The design may dynamically vary the amount of ultrasonic energydelivered to the surgical area in response to the observed actual vacuum, andcan actively vary the amount of power delivered to the surgical area based on thesize of the particle and the resultant vacuum realized.
