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.