Photodisruptive laser fragmentation of tissue

Abstract

A method of photodisruptive laser surgery includes selecting a target region of a tissue for fragmentation, directing a beam of laser pulses to the selected target region of the tissue, and forming cells in the target region of the tissue by directing the laser beam to generate cell boundaries. The cells can be arranged in regular or irregular arrays. The cells can be generated in parallel or successively, with cell sizes and laser parameters which reduce the time of ophthalmic surgery considerably.

1 . A method of fragmenting biological tissue with a photodisruptive laser, comprising the steps of:
 selecting a target region of the tissue for fragmentation;   directing a beam of laser pulses to the selected target region of the tissue; and   directing the laser beam to generate cell boundaries in the selected target region of the tissue to form cells in the selected target region.   
     
     
         2 . The method of  claim 1  wherein the tissue is a tissue of an eye. 
     
     
         3 . The method of  claim 2 , wherein the tissue is a crystalline lens of the eye. 
     
     
         4 . The method of  claim 1 , comprising:
 inserting an aspiration needle into the selected target region; and   removing fragmented tissue from the selected target region already scanned by the laser beam by using the aspiration needle.   
     
     
         5 . The method of  claim 4 , the forming the cells comprising:
 forming cells with size sufficiently small to pass through the aspiration needle.   
     
     
         6 . The method of  claim 1 , the forming the cells comprising:
 forming the cells arranged in an array.   
     
     
         7 . The method of  claim 6 , wherein the array is a regular array. 
     
     
         8 . The method of  claim 7 , wherein the regular array is one of a simple cubic lattice, a face centered lattice, a body centered lattice, a hexagonal lattice, a bravais lattice, and a stack of two dimensional lattices. 
     
     
         9 . The method of  claim 8 , wherein the array is essentially a random array. 
     
     
         10 . The method of  claim 1 , the forming the cells comprising:
 fragmenting the target tissue into cells of at least one of spheres and polyhedra.   
     
     
         11 . The method of  claim 1 , the forming the cells comprising:
 scanning the laser beam to form multiple cells in parallel in a layer.   
     
     
         12 . The method of  claim 1 , the forming the cells comprising:
 directing the laser beam to form individual cells successively.   
     
     
         13 . The method of  claim 1 , the forming the cells comprising at least one of:
 scanning the laser beam to form a cell array progressing from a posterior to an anterior direction; and   scanning the laser beam to form a cell array progressing from an anterior to a posterior direction.   
     
     
         14 . The method of  claim 1 , the directing the laser beam to generate cell boundaries comprising:
 generating the cell boundaries by creating layers of bubbles in the selected target region of the tissue.   
     
     
         15 . The method of  claim 14 , the creating layers of bubbles comprising at least one of:
 creating a layer of bubbles by applying a laser beam with an essentially constant power; and   creating a layer of bubbles by applying a laser beam with a varying power.   
     
     
         16 . The method of  claim 1 , wherein the directing the beam of laser pulses comprises applying the laser pulses with a laser parameter of at least one of:
 a pulse duration between 0.01 picosecond and 50 picoseconds;   a repetition rate between 10 kiloHertz and 100 megaHertz;   a pulse energy between 1 microjoule and 25 microjoule; and   a pulse target separation between 0.1 micron and 50 microns.   
     
     
         17 . The method of  claim 1 , wherein the directing the beam of laser pulses comprises applying the laser pulses with a laser parameter based on at least one of:
 a preoperative measurement of structural properties of the selected target region of the tissue; and   an age dependent algorithm.   
     
     
         18 . The method of  claim 1 , comprising:
 applying additional laser pulses to one or more locations outside the selected target region of the tissue to create an opening for an additional procedure.   
     
     
         19 . The method of  claim 1 , the method comprising:
 identifying a surgical goal; and   selecting laser parameters and method features to achieve the identified surgical goal.   
     
     
         20 . The method of  claim 19 , the surgical goal being an optimization of one or more of:
 a speed of the method of fragmenting;   a total amount of energy applied to the eye during the fragmenting; and   a total number of generated bubbles.   
     
     
         21 . The method of  claim 19 , the surgical goal being one or more of:
 maximization of the speed of the method of fragmenting;   minimization of the total amount of energy applied to the eye during the fragmenting; and   minimization of the total number of generated bubbles.   
     
     
         22 . The method of  claim 19 , comprising:
 selecting laser parameters and method features to achieve a total time of fragmentation of one of:   less than 2 minutes;   less than 1 minute; and   less than 30 seconds.   
     
     
         23 . The method of  claim 19 , comprising:
 selecting laser parameters and method features to achieve a ratio of a cell size to a bubble size of one of:   larger than 10;   larger than 100; and   larger than 1000.   
     
     
         24 . A laser system for fragmenting biological tissue, comprising:
 a pulsed laser to produce a laser beam of pulses; and   a laser control module
 to direct the laser beam to a selected target region of the tissue; and 
 to direct the laser beam to generate cell boundaries to form cells in the selected target region of the tissue. 
   
     
     
         25 . The laser system of  claim 24 , wherein the laser control module is configured to form cells in a regular array. 
     
     
         26 . The laser system of  claim 24 , the laser control module formed to generate the laser pulses with laser parameters of at least one of:
 a pulse duration between 0.01 and 50 picoseconds;   a repetition rate between 10 kHz and 100 megahertz;   a pulse energy between 1 microjoule and 25 microjoule; and   a pulse target separation between 0.1 micron and 50 microns.   
     
     
         27 . A method of fragmenting a tissue in an eye with a photodisruptive laser, comprising the steps of:
 selecting a target region in the eye for fragmentation; and   forming an array of cells in the target region by directing a beam of laser pulses to generate cell boundaries in the target region, with a cell size and laser parameters of the laser beam such that the tissue fragmentation requires a surgical time of less than two minutes, whereas a volumetric tissue fragmentation of the same target region with the same laser parameters would require a surgical time in excess of two minutes.   
     
     
         28 . The method of  claim 27 , wherein
 the laser parameters are at least one of:
 a pulse duration between 0.01 and 50 picoseconds; 
 a repetition rate between 10 kHz and 100 megahertz; 
 a pulse energy between 1 microjoule and 25 microjoule; and 
 a pulse target separation between 0.1 micron and 50 microns; and 
   the cell size is between 1 microns and 50 microns.