Patent Publication Number: US-2023157541-A1

Title: Visualization of vitreous floaters in the eye

Description:
TECHNICAL FIELD 
     The present disclosure relates generally to ophthalmic surgical systems, and more particularly to improved visualization of vitreous floaters in the eye. 
     BACKGROUND 
     During ophthalmic laser surgery, a surgeon needs to visualize features within the eye. For example, in laser vitreolysis, a surgeon directs a laser beam towards vitreous floaters in order to remove the floaters. Eye floaters are clumps of collagen proteins that form in the vitreous. These clumps disturb vision with moving shadows and distortions, and sometimes they block vision. The laser beam disintegrates the floaters, thus improving vision. However, a surgeon must be able to see the floaters in order to direct the laser beam at the floaters. 
     BRIEF SUMMARY 
     In certain embodiments, an ophthalmic surgical system for viewing an eye includes an ophthalmic microscope and a laser device. The ophthalmic microscope receives light reflected or scattered backwards from within the vitreous of the eye in order to provide an image of an object within the vitreous. The ophthalmic microscope includes a slit illumination source (which includes a light source and an optical element), a spectral filter, and oculars. The slit illumination source illuminates the eye with light, where the light source provides the light, and the optical element directs the light into the eye. The spectral filter filters out red spectral components of the light. The oculars receive the light from the eye in order to provide the image of the object. The laser device generates a laser beam to direct towards the object within the eye. 
     Embodiments may include none, one, some, or all of the following features:
         The spectral filter is disposed between the eye and the oculars and filters out the red spectral components of the light from the eye. The spectral filter may be disposed between a mirror and the oculars, where the mirror directs light from the eye to the oculars, and directs the laser beam towards the object within the eye.   The spectral filter is disposed between the light source and the eye and filters out the red spectral components of the light directed towards the eye.   The filtered-out red spectral components has wavelengths of 580 to 1000 nanometers.   The filtered-out red spectral components has wavelengths of wavelengths of 580 to 750 nanometers.   The slit illumination source further includes a linear polarizer that linearly polarizes the light to yield the light linearly polarized at a first axis. The ophthalmic surgical system further includes a crossed polarizer that cross polarizes the light reflected or scattered backwards from the eye to yield the light crossed polarized at a second axis substantially orthogonal to the first axis. The oculars receive the light crossed polarized at the second axis in order to provide the image of the object.       

     In certain embodiments, an ophthalmic surgical system for viewing an eye includes an ophthalmic microscope and a laser device. The ophthalmic microscope receives light reflected or scattered backwards from within the vitreous of the eye in order to provide an image of an object within the vitreous. The ophthalmic microscope includes a slit illumination source (which includes a light source, a linear polarizer, and an optical element), a crossed polarizer, and oculars. The slit illumination source illuminates the eye with light, where the light source provides the light, the linear polarizer linearly polarizes the light to yield the light linearly polarized at a first axis, and the optical element directs the light into the eye. The crossed polarizer cross polarizes the light reflected or scattered backwards from the eye to yield the light crossed polarized at a second axis substantially orthogonal to the first axis. The oculars receive the light crossed polarized at the second axis in order to provide the image of the object. The laser device generates a laser beam to direct towards the object within the eye. 
     Embodiments may include none, one, some, or all of the following features:
         The linear polarizer is a sheet polarizer or a dielectric polarizer.   The crossed polarizer is a sheet polarizer or a dielectric polarizer.   The ophthalmic system further includes a spectral filter that filters out red spectral components of the light.       

     In certain embodiments, an ophthalmic surgical system for viewing an eye includes an ophthalmic microscope and a laser device. The ophthalmic microscope receives light reflected or scattered backwards from within the vitreous of the eye in order to provide an image of an object within the vitreous. The ophthalmic microscope includes a slit illumination source (which includes a light source, a linear polarizer, and an optical element), a spectral filter, a crossed polarizer, and oculars. The slit illumination source illuminates the eye with light, where the light source provides the light, the linear polarizer linearly polarizes the light to yield the light linearly polarized at a first axis, and the optical element directs the light into the eye. The spectral filter filters out red spectral components of the light. The crossed polarizer cross polarizes the light reflected or scattered backwards from the eye to yield the light crossed polarized at a second axis substantially orthogonal to the first axis. The oculars receive the light crossed polarized at the second axis in order to provide the image of the object. The laser device generates a laser beam to direct towards the object within the eye. 
     Embodiments may include none, one, some, or all of the following features:
         The spectral filter is disposed between the eye and the oculars and filters out the red spectral components of the light from the eye. The spectral filter may be disposed between a mirror and the oculars, where the mirror directs light from the eye to the oculars, and directs the laser beam towards the object within the eye.   The spectral filter is disposed between the light source and the eye and filters out the red spectral components of the light directed towards the eye.   The filtered-out red spectral components has wavelengths of 580 to 1000 nanometers.   The filtered-out red spectral components has wavelengths of wavelengths of 580 to 750 nanometers.   The linear polarizer is a sheet polarizer or a dielectric polarizer.   The crossed polarizer is a sheet polarizer or a dielectric polarizer.       

     In certain embodiments, an ophthalmic surgical system for viewing an eye includes an ophthalmic microscope and a laser device. The ophthalmic microscope receives light reflected or scattered backwards from within the vitreous of the eye in order to provide an image of an object within the vitreous. The ophthalmic microscope includes a slit illumination source (which includes a light source, a linear polarizer, and an optical element), a spectral filter, a crossed polarizer, a mirror, and oculars. The slit illumination source illuminates the eye with light, where the light source provides the light, the linear polarizer linearly polarizes the light to yield the light linearly polarized at a first axis, and the optical element directs the light into the eye. The linear polarizer is a sheet polarizer or a dielectric polarizer. The spectral filter filters out red spectral components of the light having wavelengths of 580 to 750 nanometers. The spectral filter is disposed between the mirror and the oculars or between the light source and the eye. The crossed polarizer cross polarizes the light reflected or scattered backwards from the eye to yield the light crossed polarized at a second axis substantially orthogonal to the first axis. The crossed polarizer is a sheet polarizer or a dielectric polarizer. The mirror directs light from the eye to the oculars and directs a laser beam towards the object within the eye. The oculars receive the light crossed polarized at the second axis in order to provide the image of the object. The laser device generates a laser beam to direct towards the object within the eye. 
    
    
     
       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 to remove vitreous floaters, according to certain embodiments; 
         FIG.  2    is a graph illustrating the reflectivity of the retina as a function of wavelength; 
         FIGS.  3 A and  3 B  illustrate illustrates examples of red spectral components that may be filtered out by spectral filtering, according to certain embodiments; and 
         FIG.  4    illustrates an example of a method for visualizing the vitreous of a patient eye, which may be used by the system of  FIG.  1   , according to certain embodiments. 
     
    
    
     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. 
     A surgeon should be able to see vitreous floaters in order to direct a laser beam onto the floaters. Typically, the vitreous is illuminated with a slit lamp beam. However, light reflected from a floater tends to be weaker than background light, making the floater less visible. Sources of background light include Purkinje reflections (such as P 1 , P 2 , P 3 , and P 4  Purkinje reflections) from surfaces of the cornea and lens (e.g., natural or intraocular lens). A natural lens with a cataract may also backscatter light. The reflections and backscattering preserve the polarization of the incident slit illumination. Other sources of background light are reflections and red reflections from the retina. 
     Accordingly, in certain embodiments, an ophthalmic microscope uses polarization filtering to suppress the Purkinje reflections. In other embodiments, an ophthalmic microscope uses spectral filtering to suppress the red reflections. In yet other embodiments, an ophthalmic microscope uses both polarization filtering to suppress the Purkinje reflections and spectral filtering to suppress the red reflections. 
       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 example, ophthalmic laser system  10  comprises oculars  20 , a laser delivery head  22 , an illuminator (such as 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 mirror  40 , a spectral filter  60   b,  a crossed polarizer  64 , 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 spectral filter  60   a,  a linear polarizer  62 , a projection lens  47 , and an optical element such as a mirror  48 , coupled as shown. Console  32  includes a computer (such as a controller  50 ), a laser  52 , and a user interface  54 , coupled as shown. In certain embodiments, patient eye  14  has an axis (visual or optical) that defines a z-axis. Alternatively, the direction of the laser beam defines the 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. 
     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 an overview of certain embodiments, ophthalmic microscope  18  uses polarization filtering to suppress Purkinje reflections. Purkinje reflections are reflections of objects from structures of the eye. At least four Purkinje reflections are usually visible. The first Purkinje reflection P 1  is from the anterior surface of the cornea. The second Purkinje reflection P 2  is from the posterior surface of the cornea. The third Purkinje reflection P 3  is from the anterior surface of the lens. The fourth Purkinje reflection P 4  is from the posterior surface of the lens. Unlike the others, P 4  is an inverted image. 
     According to the overview, ophthalmic microscope  18  receives light reflected or scattered backwards from within the vitreous of eye  14  to provide an image of an object within the vitreous. Ophthalmic microscope  18  includes slit illumination source  26 , crossed polarizer  64 , and oculars  20 . Slit illumination source  26  illuminates eye  14  with a sheet of light and includes light source  43 , linear polarizer  62 , and an optical element such as objective lens  42 . Light source  43  provides light, and linear polarizer  62  linearly polarizes the light to yield light linearly polarized at a first axis. Objective lens  42  directs the light into eye  14 . Crossed polarizer  64  cross polarizes the light from the eye to yield light crossed polarized at a second axis substantially orthogonal to the first axis. Oculars  20  receives the light crossed polarized at the second axis. 
     According to an overview of other embodiments, an ophthalmic microscope  18  uses spectral filtering to suppress red reflections. Red reflections are the red-orange reflections from the back of the eye. According to the overview, ophthalmic microscope  18  receives light reflected or scattered backwards from within the vitreous of eye  14  to provide an image of an object within the vitreous. Ophthalmic microscope  18  includes slit illumination source  26 , spectral filter  60  ( 60   a  and/or  60   b ), and oculars  20 . Slit illumination source  26  illuminates eye  14  with a sheet of light and includes light source  43  and an optical element such as objective lens  42 . Light source  43  provides light, and objective lens  42  directs the light into eye  14 . Spectral filter  60  ( 60   a  and/or  60   b ) filters out the red spectral components to reduce the red spectral components of the light. Spectral filter  60   b  may be disposed between eye  14  and oculars  20  (e.g., between mirror  40  and oculars  20 ), and/or spectral filter  60   a  may be disposed between light source  43  and eye  14 . Oculars  20  receives the light crossed polarized at the second axis. According to an overview of yet other embodiments, an ophthalmic microscope uses both polarization filtering to suppress the Purkinje reflections and spectral filtering to suppress the red reflections. 
     In more detail, in certain embodiments, oculars  20  allow operator eye  12  to view patient eye  14 . The illuminator (e.g., 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. 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  directs the light towards prism mirror, which directs the slit of light into patient eye  14 . 
     Spectral filter  60  filters out red spectral components to reduce the red spectral components of the light. Spectral filter  60  may be located at any suitable point of the optical path, such as at a point that is not exposed to the laser beam. In certain embodiments, spectral filter  60   b  is disposed between eye  14  and oculars  20  and reduces the red spectral range of the light reflected or scattered backwards from eye  14 . In other embodiments, spectral filter  60   a  is disposed between light source  43  and eye  14  and reduces the red spectral range of the light directed towards eye  14 . Spectral filter  60  may filter out any suitable red spectral components. For example, the filtered-out components may be 580 to 1000 nanometers (nm), such as 580 to 750 nanometers. Examples of spectral filter  60  includes short pass filters (used in the photographic industries) and cobalt blue filters (used in the ophthalmic industries). 
     Any suitable configuration of polarizers may be used. In certain embodiments, linear polarizer  62  linearly polarizes light to yield light linearly polarized at a first axis, which is directed into eye  14 . Crossed polarizer  64  cross polarizes the light from the eye to yield light crossed polarized at a second axis substantially orthogonal (e.g., within 10, 5, or 3 degrees of orthogonal) to the first axis. Examples of polarizers include sheet or dielectric polarizers. 
     In certain embodiments, laser delivery head  22  delivers a laser beam from laser  52  of console  32  towards 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  and collimator  38  direct a parallel laser beam to mirror  40  in order to focus the laser beam onto the image plane of ophthalmic microscope  18 . Zoom system  36  includes optical elements that change the spot size of the laser beam that exits fiber  34 . An optical element can act on (e.g., transmit, reflect, refract, diffract, collimate, condition, shape, focus, modulate, and/or otherwise act on) light such as a laser beam. Collimator  38  collimates the laser beam, and mirror  40  directs the beam through objective lens  42 , which focuses the beam. In the embodiments, mirror  40  is a dichroic mirror that is reflective for the laser beam wavelength and transmissive for visible light. 
     Base  30  supports laser delivery head  22  and slit illumination source  24 . Joystick  28  moves base  30  in the x-, y-, and/or z-directions. Console  32  includes components that support the operation of system  10 . Controller  50  of console  32  is a computer that controls of the operation of components of system  10 , e.g., joystick  28 , base  30 , laser delivery head  22 , slit illumination source  26 , laser  52 , and/or user interface  54 . For example, in response to instructions from joystick  28 , controller  50  moves the laser delivery head  22  according to the instructions. Laser  52  generates the laser beam that has a cone-shaped energy profile that focuses energy onto a point. Any suitable laser  30  may be used, e.g., a femtosecond or nanosecond laser 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 1200 nm. User interface  54  communicates information between the operator and system  10 . 
       FIG.  2    is a graph  80  illustrating the reflectivity of the retina as a function of wavelength. According to graph  80 , the red part of the spectrum dominates the reflectivity of the retina, which causes the retina to appear to be red when viewed through a slit lamp microscope. This is called the “red reflex” of the retina. Certain embodiments described herein filter out red spectral components to reduce the red reflex. 
       FIGS.  3 A and  3 B  illustrate illustrates examples of red spectral components  82  ( 82   a,    82   b ) that may be reduced by spectral filtering.  FIG.  3 A  shows red spectral components  82   a  of 580 to 750 nm that may be used for an incandescent light source.  FIG.  3 B  shows red spectral components  82   b  of 580 to 750 nm that may be used for a halogen light source or a light-emitting diode (LED) light source. 
       FIG.  4    illustrates an example of a method for visualizing the vitreous of patient eye  14 , which may be used by ophthalmic laser system  10  of  FIG.  1   , according to certain embodiments. 
     The method starts at step  110 , where light source  43  of an illuminator provides light. Linear polarizer  62  polarizes the light at step  112  to yield the light linearly polarized at a first axis. In certain embodiments, spectral filter  60   a  may filter out red spectral components at step  114   a.  In the embodiments, spectral filter  60   a,  which may be disposed between light source  43  and eye  14 , reduces the red spectral range of the light directed towards eye  14 . The filtered-out components may have wavelengths of 580 to 1000 nanometers, such as 580 to 750 nanometers. Mirror  23  directs light towards eye  14  at step  116 . 
     Objective lens  42  receives light reflected or scattered backwards from eye at step  120 . In certain embodiments, spectral filter  60   b  may filter out red spectral components at step  114   b,  e.g., if the red light was not previously partially or fully filtered out. In the embodiments, spectral filter  60   b,  which may be disposed between eye  14  and oculars  20  (e.g., between mirror  40  and oculars  20 ), reduces the red spectral components of the light from eye  14 . Cross polarizer  64  cross polarizes the light at step  122  to yield the light crossed polarized at a second axis substantially orthogonal to the first axis. Oculars  20  present an image of patient eye  14  to operator eye  12  at step  124 . 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).