Automated laser workstation for high precision surgical and industrial interventions

Abstract

A method, apparatus and system for template-controlled, precision laser interventions is described that greatly improves the accuracy, speed, range, reliability, versatility, safety, and efficacy of interventions such as laser microsurgery, particularly ophthalmic surgery, and industrial micromachining. The instrument and system are applicable to those specialties wherein the positioning accuracy of laser lesions is critical, wherever accurate containment of the spatial extent of a laser lesion is desirable, and/or whenever precise operations on a target or series of targets subject to movement during the procedure are to be effected. A key object of the present invention is to implement a fully integrated approach based on a number of different instrumental functions all operating in concert within a single, fully automated unit. Each of the complementary, and at times competing, functions requires its own technologies and corresponding subassemblies. The system includes a user interface, wherein the user can either draw, adjust, or designate particular template patterns overlaid on a live video images of the target (such as the cornea) and provide the means for converting the template pattern into a sequence of automatic motion instructions to direct a laser beam to focus sequentially on a number of points in three dimensional space which will, in turn, replicate the designated template pattern into the corresponding surgical or industrial site. The user interface also continuously presents three dimensional visual information to the surgeon/user during the operation, as to the surrounding features of the subject tissue, the topography of the surface to be operated upon or below said surface at a prescribed depth, and as to the precise aiming location and depth of penetration of the treatment laser beam. The system thus comprises the following key elements: (1) a user interface, consisting of a video display, microprocessor and controls, (2) an imaging system, which may include a surgical video microscope with zoom capability, (3) an automated 3D target acquisition and tracking system that can follow the movements of the subject tissue, for example an eye, during the operation, thus allowing the surgeon/user to predetermine his firing pattern based on an image which is automatically stabilized over time. Tracking is considered a critical element of the system designed not only to diagnose, but to also select treatment, position the treatment beam and image the tissue simultaneously with the treatment, while assuring safety at all times, (4) a laser, with which can be focused so that only the precise lesions described by the user interface are effected. The laser parameters are selected to allow execution of the desired procedure at a high rate of independently targeted shots per second, as well as tuning to selectively generate photodisruption of tissues, or photocoagulation as desired, (5) a diagnostic system, incorporating a mapping and topography means for measuring precise surface shapes prior to and subsequent to a procedure, said measurements to be executed on-line within time scales not limited to human response times, and (6) a fast reliable safety means, whereby the laser firing is interrupted automatically, should any conditions arise to warrant such interruption of the procedure.

What is claimed is:  
     
         1 . A laser surgery system for treating a tissue located at a site of an eye, the system comprising: 
 a laser making a beam of a treatment light energy, the treatment light energy being deliverable to the site;    an imaging system forming an image of a natural tissue structure, the natural tissue structure being in proximity to the site, the image of the site being visible to the user;    a detector having the image of the structure formed thereon and generating a first electrical signal in response to the image of the structure, the first signal being related to a position of the structure; and    a processor adapted to generate a second electrical signal in response to the first electrical signal, the second signal stabilizing the beam of treatment light energy delivered to the tissue treatment site as the light energy is delivered to the tissue treatment site.    
     
     
         2 . The system of  claim 1  wherein the imaging system forms a real time image of the tissue treatment site, and the second signal stabilizes the real time image of the tissue treatment site as seen by the user.  
     
     
         3 . The system of  claim 1  wherein the tissue treatment site corresponds to a corneal tissue site of the eye, and the structure corresponds to a limbal structure of the eye.  
     
     
         4 . The system of  claim 1  wherein at least one processor comprises a computer program adapted to control a delivery of the light energy to the tissue treatment site in response to at least one action of the user.  
     
     
         5 . The system of  claim 1  wherein the processor comprises a central processing unit and a computer program adapted to determine the position of the structure.  
     
     
         6 . The system of  claim 1  wherein the processor comprises an analog circuit measuring a position of the structure.  
     
     
         7 . The system of  claim 2  further comprising a display visible to the user, the display showing the stabilized real time image of the site.  
     
     
         8 . The system of  claim 7  wherein the image of the site is formed on a camera, the camera being electronically coupled to the display.  
     
     
         9 . The system of  claim 1  wherein the optical system further comprises a movable mirror, and the movable mirror moves in response to the second signal.  
     
     
         10 . The system of  claim 1  further comprising: 
 optical path means for receiving the laser beam, for aiming the beam at a position in X-Y directions transverse to the beam, and for focusing the beam at a distance in a Z direction as desired toward the tissue treatment site;  
 beam steering means connected to the optical path means for controlling the position at which the beam is aimed in X-Y directions;  
 beam focusing means connected to the optical path means for controlling the distance at which the laser beam is focused;  
 tracking means for tracking eye movements during the progress of the surgery, including X-Y tracking means for tracking the structure of the eye in X and Y directions, and Z tracking means for tracking movements of the eye in the Z direction toward and away from the system; and  
 safety interrupt means for interrupting delivery of the laser beam to the patient when it is determined that the tracking means has lost the structure being tracked.  
 
     
     
         11 . A method of treating a tissue located at a site of an eye of a patient with a laser, the tissue treatment site being seen by a user, the method comprising: 
 making a beam of a treatment light energy with the laser, the treatment light energy being deliverable to the tissue treatment site;    forming a real-time image of the tissue treatment site and an image of a natural tissue structure with an optical system, the natural tissue structure being in proximity to the tissue treatment site;    measuring a position of the tissue structure from a first electrical signal generated by a detector, the detector having the image of the structure formed thereon, the first signal being related to the position of the structure;    generating a second electrical signal in response to the measured position of the structure, the second signal stabilizing the beam of treatment light energy as the treatment light energy is delivered to the tissue treatment site; and    transmitting the stabilized beam of treatment light energy to the tissue treatment site.    
     
     
         12 . The method of  claim 11  further comprising stabilizing a real time image of the tissue treatment site as seen by the user while the treatment light energy is delivered to the tissue treatment site.  
     
     
         13 . The method of  claim 12  further comprising moving a mirror in response to the second signal to stabilize the real-time image of the site as seen by the user.  
     
     
         14 . The method of  claim 11  further comprising ablating a surface of a cornea of the eye by pulsing the laser.  
     
     
         15 . The method of  claim 11  further comprising: 
 receiving the beam with an optical delivery system;  
 aiming the beam at a position in X-Y directions transverse to the beam with the optical delivery system, the optical delivery system comprising a beam steering optic;  
 focusing the beam in a Z direction at a distance with the optical delivery system, the optical delivery system comprising a front lens element;  
 controlling the position at which the beam is aimed in X-Y directions using the beam steering optic of the optical delivery system;  
 controlling the distance at which the laser beam is focused in the Z direction with the beam focusing optic of the optical delivery system;  
 tracking eye movements of the patient during the progress of the surgery by tracking eye movements in X and Y directions with the detector and by tracking eye movements in a Z direction with a second optical detector;  
 automatically shifting the beam steering optic and the beam focusing optic with a processor as the eye is tracked through X, Y and Z directions to change the position of the laser beam and the distance at which the laser beam is focused so as to follow movements of the eye; and  
 automatically interrupting delivery of the laser beam to the tissue treatment site when it is determined via the processor that the sensor has lost the structure being tracked.