Patent Publication Number: US-2023157877-A1

Title: Multiplexing a laser beam to fragment eye floaters

Description:
TECHNICAL FIELD 
     The present disclosure relates generally to laser vitreolysis systems and methods, and more particularly to multiplexing laser beams to fragment eye floaters. 
     BACKGROUND 
     In ophthalmic laser surgery, a surgeon may direct a laser beam into the eye to treat the eye. For example, a laser beam may be directed into the vitreous to disintegrate eye floaters. Eye floaters are clumps of collagen proteins that form in the vitreous. These clumps disturb vision with moving shadows and distortions. The laser beam may be used to remove the floaters, thus improving vision. 
     BRIEF SUMMARY 
     In certain embodiments, an ophthalmic laser system includes a laser device, an ophthalmic microscope, and a controller. The laser device directs laser pulses towards a target within an eye. An axis of the eye defines a z-axis. The z-axis defines an xy-plane orthogonal to the z-axis, and the xy-plane defines a target xy-plane where the target is located. The target has a dimension in the target xy-plane. The laser device includes a laser configured to generate a laser beam and one or more laser beam multiplexers. Each laser beam multiplexer modulates the laser beam to yield a pulse pattern of laser pulses in the target xy-plane. The pulse pattern has coverage related to the dimension of the target to limit movement of the target. The ophthalmic microscope gathers light reflected from within the eye to yield an image of the eye. The controller instructs the laser device to direct the laser pulses towards the target to yield the pulse pattern of laser pulses 
     Embodiments may include none, one, some, or all of the following features:
         The target is an eye floater.   The multiplexer(s) include a first multiplexer configured to yield a first pulse pattern and a second multiplexer configured to yield a second pulse pattern. The controller may instruct the laser device to use the first multiplexer or the second multiplexer. The first pulse pattern may provide smaller coverage, and the second pulse pattern may provide larger coverage. The first pulse pattern may provide sparser coverage, and the second pulse pattern may provide denser coverage.   The multiplexer(s) include a spatial light modulator that creates a first pulse pattern or a second pulse pattern. The controller may instruct the spatial light modulator to create the first pulse pattern or the second pulse pattern. The first pulse pattern may provide smaller coverage, and the second pulse pattern may provide larger coverage. The first pulse pattern may provide sparser coverage, and the second pulse pattern may provide denser coverage.   The controller determines the dimension of the target from user input.   The controller determines the dimension of the target by performing image processing on the image of the eye to measure the dimension.   The controller selects the pulse pattern of laser pulses in accordance with the dimension of the target.   A laser beam multiplexer may be a diffractive optical element (DOE), a diffraction grating, a holographic optical element (HOE), an interferometer, a spatial light modulator (SLM), a polarization multiplexer, or any combination of the preceding.       

     In certain embodiments, a method for using an ophthalmic laser system includes instructing, by a controller, a laser device to direct laser pulses towards a target within an eye to yield a pulse pattern of laser pulses. An axis of the eye defines a z-axis. The z-axis defines an xy-plane orthogonal to the z-axis, and the xy-plane defines a target xy-plane where the target is located. The target has a dimension in the target xy-plane. A laser beam is generated by a laser of the laser device. The laser beam is modulated, by laser beam multiplexer(s) of the laser device, to yield the pulse pattern. The pulse pattern has coverage related to the dimension of the target to limit movement of the target. The laser pulses are directed, by the laser device, towards the target within the eye. Light reflected from within the eye is gathered, by an ophthalmic microscope, to yield an image of the eye. 
     Embodiments may include none, one, some, or all of the following features:
         The multiplexer(s) include a first multiplexer configured to yield a first pulse pattern and a second multiplexer configured to yield a second pulse pattern. The method may include instructing, by the controller, the laser device to use the first multiplexer or the second multiplexer.   The multiplexer(s) include a spatial light modulator that creates a first pulse pattern or a second pulse pattern. The method may include instructing, by the controller, the spatial light modulator to create the first pulse pattern or the second pulse pattern.       

     In certain embodiments, an ophthalmic laser system includes a laser device, an ophthalmic microscope, and a controller. The laser device directs laser pulses towards a target within an eye, where the target is an eye floater. An axis of the eye defines a z-axis. The z-axis defines an xy-plane orthogonal to the z-axis, and the xy-plane defines a target xy-plane where the target is located. The target has a dimension in the target xy-plane. The laser device includes a laser configured to generate a laser beam and one or more laser beam multiplexers. Each laser beam multiplexer modulates the laser beam to yield a pulse pattern of laser pulses in the target xy-plane. The pulse pattern has a coverage related to the dimension of the target to limit movement of the target. The multiplexer(s) includes a first multiplexer configured to yield a first pulse pattern and a second multiplexer configured to yield a second pulse pattern, or a spatial light modulator configured to create the first pulse pattern and the second pulse pattern. The first pulse pattern provides smaller coverage, and the second pulse pattern provides larger coverage. The first pulse pattern provides sparser coverage, and the second pulse pattern provides denser coverage. A laser beam multiplexer may be a diffractive optical element (DOE), a diffraction grating, a holographic optical element (HOE), an interferometer, a spatial light modulator (SLM), a polarization multiplexer, or any combination of the preceding. The ophthalmic microscope gathers light reflected from within the eye to yield an image of the eye. The controller instructs the laser device to direct the laser pulses towards the target to yield the pulse pattern of laser pulses. The controller instructs the laser device to direct the plurality of laser pulses towards the target to yield the pulse pattern of laser pulses. 
     Embodiments may include the following feature: 
     The controller: determines the dimension of the target from user input or by performing image processing on the image of the eye to measure the dimension; selects the pulse pattern of laser pulses in accordance with the dimension of the target; and instructs the laser device to use the first multiplexer or the second multiplexer or instructs the spatial light modulator to create the first pulse pattern or the second pulse pattern. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    illustrates an example of an ophthalmic laser system that may be used to perform laser vitreolysis on a patient eye, according to certain embodiments; 
         FIG.  2    illustrates an example of a laser pulse causing a floater to jump; 
         FIG.  3    illustrates an example of the coverage of a pulse pattern relative to a floater; 
         FIG.  4    illustrates an example of a multiplexed pattern, which may be used by the ophthalmic laser system of  FIG.  1   ; and 
         FIGS.  5 A to  5 D  illustrate examples of multiplexed patterns, which may be used by the ophthalmic laser system of  FIG.  1   ; and 
         FIG.  6    illustrates an example of a method for fragmenting eye floaters, which may be used by the ophthalmic laser system of  FIG.  1   . 
     
    
    
     DESCRIPTION OF EXAMPLE EMBODIMENTS 
     Referring now to the description and drawings, example embodiments of the disclosed apparatuses, systems, and methods are shown in detail. The description and drawings are not intended to be exhaustive or otherwise limit the claims to the specific embodiments shown in the drawings and disclosed in the description. Although the drawings represent possible embodiments, the drawings are not necessarily to scale and certain features may be simplified, exaggerated, removed, or partially sectioned to better illustrate the embodiments. 
     In laser vitreolysis, laser pulses are used to disintegrate eye floaters to improve vision. In certain situations, the laser pulses have a pulse energy of approximately 3 to 10 milliJoules (mJ), which can create a rapidly expanding cavitation bubble. The acceleration of the bubble-vitreous interface can reach a point where it can mechanically disintegrate a floater. If the pulse hits the center of a floater, the bubble disintegrates the floater. However, if the pulse hits the periphery, the bubble rapidly pushes the floater, causing it to jump. 
     In certain embodiments, a laser device directs laser pulses towards a floater within an eye. The laser device includes a laser beam multiplexer that splits a laser beam to yield a pattern of pulses where some of the pulses surround the floater, reducing the likelihood the floater will jump. 
       FIG.  1    illustrates an example of an ophthalmic laser system  10  that an operator (with an operator eye  12 ) may use to perform laser vitreolysis on a patient eye  14  to remove vitreous floaters, according to certain embodiments. Vitreous floaters are microscopic collagen fibers within the vitreous that tend to clump together. These clumps scatter light and cast shadows on the retina, which appear as visual disturbances in the vision of the patient. Ophthalmic laser system  10  allows the operator to see floaters in relation to the retina and lens of the eye, and then direct a laser beam to break up the floaters. In the illustrated example, patient eye  14  has an axis (visual or optical) that defines a z-axis. The z-axis defines an x-axis and a y-axis orthogonal to the z-axis. In turn, the x-axis and the y-axis define an xy-plane. 
     In the example, ophthalmic laser system  10  comprises oculars  20 , a laser delivery head  22 , a slit illumination source  26 , a positioning device (such as a joystick  28 ), a base  30 , and a console  32 , coupled as shown. Laser delivery head  22  includes a laser fiber  34 , a distal end  35 , a zoom system  36 , a collimator  38 , a beam multiplexer  39 , a mirror  40 , and an objective lens  42 , coupled as shown. Slit illumination source  26  includes a light source  43 , condenser lens  44 , a variable aperture  45 , a variable slit plate  46 , a projection lens  47 , and a mirror  48 . Console  32  includes a computer (such as a controller  50 ), a laser  52 , and a user interface  54 , coupled as shown. 
     As an overview, ophthalmic laser system  10  includes a laser device  16  (e.g., laser  52 , laser fiber  34 , and laser delivery head  22 ) and an ophthalmic microscope  18  such as a slit lamp (e.g., oculars  20 , objective lens  42 , mirror  48 , and slit illumination source  26 ). Operator eye  12  utilizes the optical path from oculars  20  through mirror  40 , objective lens  42 , and mirror  48  to view patient eye  14 . A laser beam follows the laser path from laser  52  through laser delivery head  22  and mirror  48  to treat patient eye  14 . 
     According to the overview, laser device  16  directs a laser beam comprising laser pulses towards a target within eye  14 . The target has a dimension (e.g., length) in the xy-plane where the target is located. Ophthalmic microscope  18  gathers light reflected from within eye  14  to yield an image of eye  14 . Beam multiplexer  39  splits the laser beam into a plurality of laser beams or otherwise modulates the laser beam to yield a plurality of laser pulses. Controller  50  instructs laser device  16  to direct the laser pulses towards the target such that a subset of the laser pulses surround the target, reducing the likelihood of causing the target to jump. 
     In more detail, in certain embodiments, oculars  20  allow operator eye  12  to view patient eye  14 . Laser delivery head  22  delivers a laser beam of laser pulses from laser  52  of console  32  to patient eye  14 . Laser fiber  34  of delivery head  22  transports the laser beam from laser  52  to the end of fiber  34 . Zoom system  36  includes optical elements that change the spot size of the laser beam that exits fiber  34 . Collimator  38  collimates the laser beam, and mirror  40  directs the beam through objective lens  42 , which focuses the beam. Zoom system  36  and collimator  38  are configured to direct a parallel laser beam to mirror  40 , in order to focus the laser beam onto the image plane of ophthalmic microscope  18 . Mirror  40  may be a dichroic mirror that is reflective for the laser beam wavelength and transmissive for visible light. 
     Slit illumination source  26  of laser system  10  provides light that illuminates the surgical site of patient eye  14 . In certain embodiments, slit illumination source  26  may illuminate a floater coaxially with the laser beam or at an oblique angle to the beam. Such oblique illumination reduces light scattered from the cornea and human lens and also reduces red reflex from the retina. Oblique illumination resembles dark field illumination. 
     Slit illumination source  26  includes light source  43 , which emits light such as a high-intensity illumination light. Condenser lens  44  directs the light towards variable aperture  45  and variable slit plate  46 . Variable aperture  45  defines the height of the light in the y-direction, and variable slit plate  43  defines the width of the light in the x-direction to form the light into a slit shape. Projection lens  47  directions the light towards prism mirror  48 , which directs the slit of light into patient eye  14 . 
     Base  30  supports laser delivery head  22  and slit illumination source  26 . Joystick  28  moves base  30  in the x-, y-, and z-directions. Console  32  includes components that support the operation of system  10 . Controller  50  of console  32  controls of the operation of components of system  10 , e.g., base  30 , laser delivery head  22 , slit illumination source  26 , laser  52 , and/or user interface  54 . Laser  52  supplies the laser beam. Any suitable laser  30  may be used, e.g., a femtosecond or nanosecond laser (e.g., Q-switched) with any suitable crystal (e.g., Nd:YAG, Erbium:YAG, Ti: Sapphire, or ruby). The laser beam may have any suitable wavelength, e.g., in a range from 500 nm to 1100 nm. User interface  54  communicates information between the operator and system  10 . 
     Laser beam multiplexer  39  multiplexes (e.g., splits or otherwise modulates) a laser beam to form a plurality of laser pulses that yield a multiplexed focal pulse pattern. A multiplexed pulse pattern distributes pulses in the x-, y-, and/or z-directions. For example, the pulses may form a pattern, e.g., an array, in the xy-plane of the floater. As another example, the pulses may form multiple patterns (e.g., arrays) in the z-direction and parallel to the xy-plane of the floater, yielding a three-dimensional (3D) volume (e.g., a 3D array). 
     Laser beam multiplexer  39  comprises any suitable optical element that can split a laser beam into more than one beam or otherwise modulate the laser beam to yield a pulse pattern with two or more pulses. In general, an optical element is a component that can act on (e.g., transmit, reflect, refract, diffract, collimate, condition, shape, focus, modulate, and/or otherwise act on) a laser beam. Examples of laser beam multiplexer  39  include a diffractive optical element (DOE), a diffraction grating, a holographic optical element (HOE), an interferometer (e.g., a Michelson, Mach-Zehnder, or other interferometer), a spatial light modulator (SLM), a polarization multiplexer (e.g., Wollaston prism), and a combination of different beam multiplexers (e.g., 5× diffractive multiplexer and a Wollaston-doubler). 
     Laser device  16  may include one or more multiplexers  39  that yield one or more pulse patterns. In certain embodiments, laser device  16  is a simple device that includes one multiplexer  39  that yields one pulse pattern. In other embodiments, laser device  16  includes a plurality of multiplexers that yield different pulse patterns. Each multiplexer can be moved into and out of the beam path with a mechanical actuator. In the embodiments, in response to the selection of a pattern by, e.g., a surgeon, controller  50  identifies the multiplexer  39  that yields the selected pattern, and instructs an actuator to move the identified multiplexer  39  into place. In response, the actuator moves the identified multiplexer  39  into the laser beam path. 
     In yet other embodiments, the multiplexer  39  is a spatial light modulator (SLM) that can modulate amplitude, phase, and/or polarization of the laser beam in space and/or time to produce different patterns. In the embodiments, in response to the selection of a pattern by, e.g., a surgeon, controller  50  instructs the spatial light modulator to modulate the laser beam to produce the selected pattern. 
       FIG.  2    illustrates an example of a laser pulse causing a floater  110  to jump. In the example, floater  110  is approximately 100 to 300 microns across. A 1 milliJoule (mJ) laser pulse creates a rapidly expanding cavitation bubble  108  with a peak diameter of approximately 1 millimeter (mm) in approximately 1.19 milliseconds (ms). If the pulse hits the center of floater  110 , the bubble fragments floater  110 . However, if the pulse hits the periphery of floater  110 , the bubble rapidly pushes floater  110 , causing it to jump. In the example, floater  110  moves a distance of, e.g., 1 mm, such that the laser will have to be redirected with the positioning device. 
       FIG.  3    illustrates an example of the coverage  113  of a pulse pattern  112  relative to a floater  110 . In the illustrated example, the dashed lines represent the pulse coverage  113  of a pulse pattern  112 , i.e., the area enclosed by the outermost pulses of the pulse pattern. Pulse pattern  112  places a subset (which may be part of a set or the whole set) of the pulses in the path where floater  110  could jump in order to limit the movement of floater  110 . Accordingly, coverage  113  of pulse pattern  112  may be larger than at least a majority of floater  110 . For example, coverage  113  may be at least as large as, or at least as 25, 40, or 50 percent larger than floater  110 . Floaters  110  tend to move more in the x- and y-directions than in the z-direction, so pulse pattern  112  may place more pulses in the x- and y-directions around floater  110 . 
     The coverage  113  may be at least as large as a dimension  114  that indicates the general size of floater  110  such that the outermost portion of coverage  113  surrounds dimension  114 . Dimension  114  may be measured in any suitable direction in three-dimensional space. In certain embodiments, ophthalmic microscope  18  provides an image of floater  110  in a target xy-plane where floater  110  (e.g., approximately the centroid of floater  110 ) is located, so dimension  114  is measured in the target xy-plane. 
     Dimension  114  ( 114   a,    114   b ) may measure any suitable portion of floater  110  that indicates the size of floater  110 . For example, dimension  114   a  measures the longest part of floater  110 , and dimension  114   b  measures the longest part of a majority (e.g., 50 to 70, 70 to 90, and/or 90 to 100 percent) of the area of floater  114   b.  In some cases, dimension  114   b  may be used to provide greater coverage if using dimension  114   a  still causes floaters  110  to jump. A pulse pattern  112  with coverage  113  ( 113   a,    113   b ) may be selected according to dimension  114 . For example, coverage  113   a  covers dimension  114   a,  and coverage  113   b  covers dimension  114   b.  Coverage  113  may be substantially centered about the centroid of floater  110  to reduce the likelihood of jumping. 
     Laser device  16  may include one or more multiplexers  39  that yield patterns with different coverage  113 , e.g., one multiplexer provides smaller coverage and another provides larger coverage. For example, laser device  16  includes multiple multiplexers  39  that yield patterns with different coverage  113 , or one multiplexer  39  (e.g., a SLM) that can create patterns with different coverage  113 . The coverage  113  may be for smaller (e.g., 50 μm) to larger (e.g., 1 mm) floaters, e.g., a range of 10 microns to 5 mm, such as 20 microns to 3 mm. Coverage  113  may be divided into ranges (which may overlap), where a particular pattern yields a particular range. For example, coverage  113  is divided into smaller coverage for smaller floaters  110  (e.g., 20 microns to 120 microns), average coverage for the most common size of floaters  110  (e.g., 100 microns to 1 mm), and larger coverage for larger floaters  110  (e.g., 0.9 to 3 mm). In the example, one pattern provides smaller floater coverage, another provides average floater coverage, and yet another provides larger floater coverage. 
       FIG.  4    illustrates an example of a multiplexed array pattern  132  in the xy-plane, which may be used by ophthalmic laser system  10  of  FIG.  1   . A laser beam is multiplexed (e.g., split or otherwise modulated) into multiple beams (e.g., 2 to 5, 6 to 9, or 10 or more beams) to form laser pulses that surround floater  110 . In the illustrated example, the pulse coverage of pattern  132  is at least as large as the longest part of a majority (approximately 90%) of floater  110 . The outermost pulses surround the majority of floater  110 , and the central pulse hits floater  110 . In other examples, the coverage of the array is at least as large as the longest dimension of floater  110 , such that the outermost pulses of the array surround the whole floater  110 . 
       FIGS.  5 A to  5 D  illustrate examples of multiplexed array patterns  132  ( 132   a  to  132   d ) in the xy-plane, which may be used by ophthalmic laser system  10  of  FIG.  1   . A pulse pattern may have any suitable pattern in the xy-plane of the target. In the examples, patterns  132  are symmetrical about a central pulse. Pattern  132   a  includes a central pulse with three outer pulses that form a triangle. Pattern  132   b  includes a central pulse with four outer pulses that form a square. Pattern  132   c  includes a central pulse with five outer pulses that form a pentagram. Pattern  132   d  includes a central pulse with six outer pulses that form a hexagon. 
     In the examples, patterns  132  have different pulse densities. Pattern  132   a  has the sparsest coverage, pattern  132   b  has denser coverage, pattern  132   c  has even denser coverage, and pattern  132   d  has the densest coverage. A pattern  132  with sparser coverage may be used for thinner, sparser floaters, and a pattern  132  with a denser coverage may be used for thicker, denser floaters. 
     Similar to multiplexers  39  discussed above with patterns of different coverage, laser device  16  may include one or more multiplexers  39  that yield patterns of different density. For example, laser device  16  includes multiple multiplexers  39  that yield patterns of different density or one multiplexer  39  (e.g., a SLM) that can create patterns of different density. 
       FIG.  6    illustrates an example of a method for fragmenting eye floaters, which may be used by ophthalmic laser system  10  of  FIG.  1   . In the example, controller  50  of system  10  may perform at least some steps of the method. The method starts at step  210 , where a dimension of the target, e.g., floater  110 , is determined. In certain embodiments, the user determines the dimension of the target. In other embodiments, controller  50  determines the dimension of the target by receiving user input of the dimension. In yet other embodiments, controller  50  performs image processing on an image of the target (provided by, e.g., the ophthalmic microscope) to measure the dimension. 
     A pulse pattern is selected in accordance with the dimension at step  212 . As described above, when treating floaters, coverage larger than most of the area of the floater reduces the likelihood that the floater will jump and increases the likelihood of disintegrating the floater. In certain embodiments, the user selects the pulse pattern. In other embodiments, controller  50  selects the pulse pattern in response to user input of the selection. In yet other embodiments, controller  50  automatically selects a pulse pattern that covers the dimension of the target. 
     Controller  50  instructs laser device  16  to use the selected pattern at step  214 . In certain embodiments, controller  50  instructs the laser device to use a laser beam multiplexer that yields the selected pulse pattern. In other embodiments, controller  50  instructs a spatial light modulator to create the selected pulse pattern. 
     Controller  50  instructs laser device  16  to direct the laser pulses towards the target at step  216 . The user (e.g., using joystick  28 ) or controller  50  (e.g., using tracking) may aim the pulses. Aiming the pulses such that the approximate center of the pattern hits the approximate center of the target decreases the likelihood that the target jumps. 
     The target may be fragmented at step  218 . If the target has not been fragmented, the method returns to step  216  where controller  50  instructs laser device  16  to direct the laser beam towards the target. The laser beam may need to be re-aimed prior to directing the laser beam. If the target has been fragmented, the method proceeds to step  220  to end the method. The method then ends. 
     A component (such as controller  50 ) of the systems and apparatuses disclosed herein may include an interface, logic, and/or memory, any of which may include computer hardware and/or software. An interface can receive input to the component and/or send output from the component, and is typically used to exchange information between, e.g., software, hardware, peripheral devices, users, and combinations of these. A user interface is a type of interface that a user can utilize to communicate with (e.g., send input to and/or receive output from) a computer. Examples of user interfaces include a display, Graphical User Interface (GUI), touchscreen, keyboard, mouse, gesture sensor, microphone, and speakers. 
     Logic can perform operations of the component. Logic may include one or more electronic devices that process data, e.g., execute instructions to generate output from input. Examples of such an electronic device include a computer, processor, microprocessor (e.g., a Central Processing Unit (CPU)), and computer chip. Logic may include computer software that encodes instructions capable of being executed by an electronic device to perform operations. Examples of computer software include a computer program, application, and operating system. 
     A memory can store information and may comprise tangible, computer-readable, and/or computer-executable storage medium. Examples of memory include computer memory (e.g., Random Access Memory (RAM) or Read Only Memory (ROM)), mass storage media (e.g., a hard disk), removable storage media (e.g., a Compact Disk (CD) or Digital Video or Versatile Disk (DVD)), database, network storage (e.g., a server), and/or other computer-readable media. Particular embodiments may be directed to memory encoded with computer software. 
     Although this disclosure has been described in terms of certain embodiments, modifications (such as changes, substitutions, additions, omissions, and/or other modifications) of the embodiments will be apparent to those skilled in the art. Accordingly, modifications may be made to the embodiments without departing from the scope of the invention. For example, modifications may be made to the systems and apparatuses disclosed herein. The components of the systems and apparatuses may be integrated or separated, or the operations of the systems and apparatuses may be performed by more, fewer, or other components, as apparent to those skilled in the art. As another example, modifications may be made to the methods disclosed herein. The methods may include more, fewer, or other steps, and the steps may be performed in any suitable order, as apparent to those skilled in the art. 
     To aid the Patent Office and readers in interpreting the claims, Applicants note that they do not intend any of the claims or claim elements to invoke 35 U.S.C. § 112(f), unless the words “means for” or “step for” are explicitly used in the particular claim. Use of any other term (e.g., “mechanism,” “module,” “device,” “unit,” “component,” “element,” “member,” “apparatus,” “machine,” “system,” “processor,” or “controller”) within a claim is understood by the applicants to refer to structures known to those skilled in the relevant art and is not intended to invoke 35 U.S.C. § 112(f).