an ophthalmological laser surgery system having a laser , associated elements for delivering an optical beam from the laser to a patient eye location , a control unit for controlling the operation of the system and a system input / output device , is enabled by a patient data card . the data card originally contains both patient background and system control information , which is transferred to the control unit via the input / output device . during system operation , newly generated information , such as laser beam power , is stored in the data card to provide an independent record of the surgical procedure actually performed . after one use , the data card is invalidated to prevent further use .