Patent Publication Number: US-2023157537-A1

Title: Imaging a target within an eye and calibrating imaging devices

Description:
TECHNICAL FIELD 
     The present disclosure relates generally to ophthalmic laser surgical systems, and more particularly to imaging a target within an eye and calibrating imaging devices. 
     BACKGROUND 
     Laser vitreolysis uses laser beams to treat vitreous floaters and other retinal diseases. During a procedure, a laser beam is directed to the target, e.g., a floater, to fragment the target. The laser beam should be accurately and precisely delivered to the target to avoid damaging retinal tissues and ensure ocular safety. Known systems have attempted to improve accuracy and precision using image-guided laser beam delivery techniques. However, these techniques fail to provide satisfactory accuracy and precision in certain situations. 
     BRIEF SUMMARY 
     In certain embodiments, an ophthalmic laser surgical system for imaging and treating a target in an eye includes an imaging system, a treatment system, a beam combining and alignment device, a laser-OCT xy-scanner, and a computer. The eye has an eye axis that defines a z-axis, which defines xy-planes in the eye. The imaging system includes an optical coherence tomography (OCT) device that directs an OCT imaging beam along an imaging beam path towards the target in the eye, receives the OCT imaging beam reflected from the eye, and generates OCT images from the reflected OCT imaging beam. The treatment system includes a laser device that directs a laser beam along a laser beam path towards the eye. The beam combining and alignment device aligns the OCT imaging beam and the laser beam. The laser-OCT xy-scanner: receives the OCT imaging beam from the imaging system, directs the OCT imaging beam along the imaging beam path towards the eye, and scans the OCT imaging beam in an xy-plane in the eye; and receives the laser beam from the laser device, directs the laser beam along the laser beam path aligned with the imaging beam path towards the eye, and scans the laser beam in the xy-plane in the eye. The computer sends instructions to the OCT device and the laser device. 
     Embodiments may include none, one, some, or all of the following features: 
     * The target comprises an eye floater. 
     * The laser-OCT xy-scanner scans the OCT imaging beam in a continuous manner. 
     * The laser-OCT xy-scanner scans the laser beam in a stepwise manner by scanning when the laser device is not firing the laser beam and ceasing scanning when the laser device is firing the laser beam. 
     * The laser device directs the laser beam along towards a laser xy-location of a calibration pattern to yield a mark at the laser xy-location. The OCT device: directs the OCT imaging beam towards the calibration pattern; receives the OCT imaging beam reflected from the calibration pattern; and generates an OCT image of the mark on the calibration pattern from the reflected OCT imaging beam. The computer performs a registration procedure by: determining a difference between an OCT xy-location of the mark on the OCT image and the laser-xy-location of the mark; and calculating one or more correction parameters to compensate for the difference. The computer may perform the registration procedure while the laser-OCT xy-scanner is scanning in a continuous manner or in a stepwise manner. 
     * The ophthalmic laser surgical system includes a scanning laser ophthalmoscope (SLO) device that: directs an SLO imaging beam along an SLO imaging beam path towards the eye; scans, by an SLO xy-scanner, the SLO imaging beam in an xy-plane in the eye; receives the SLO imaging beam reflected from the eye; and generates SLO images from the reflected SLO imaging beam. 
     * The beam combining and alignment device mounted on a two-axis kinematic mount. 
     * The beam combining and alignment device comprising a beam combiner or a dichroic mirror. 
     In certain embodiments, an ophthalmic laser surgical system for imaging and treating a target in an eye includes an imaging system, a treatment system, a laser-OCT xy-scanner, and a computer. The eye has an eye axis that defines a z-axis, which defines xy-planes in the eye. The imaging system includes an optical coherence tomography (OCT) device and a scanning laser ophthalmoscope (SLO) device. The OCT device directs an OCT imaging beam along an imaging beam path towards the target in the eye, receives the OCT imaging beam reflected from the eye, and generates OCT images from the reflected OCT imaging beam. The SLO device directs an SLO imaging beam along an SLO imaging beam path towards the target in the eye, receives the SLO imaging beam reflected from the eye, and generates SLO images from the reflected SLO imaging beam. The SLO device includes an SLO xy-scanner that scans the SLO imaging beam in an xy-plane in the eye. The treatment system includes a laser device that directs a laser beam along a laser beam path towards the eye. The laser-OCT xy-scanner: receives the OCT imaging beam from the imaging system, directs the OCT imaging beam along the imaging beam path towards the eye, and scans the OCT imaging beam in an xy-plane in the eye; and receives the laser beam from the laser device, directs the laser beam along the laser beam path aligned with the imaging beam path towards the eye, and scans the laser beam in the xy-plane in the eye. The computer sends instructions to the OCT device and the laser device. 
     Embodiments may include none, one, some, or all of the following features: 
     * The target comprises an eye floater. 
     * The laser-OCT xy-scanner and the SLO xy-scanner scan concurrently. 
     * The OCT device determines a z-location of the target relative to the z-axis. 
     * The SLO device determines an xy-location of the target relative to an xy-plane. 
     * The SLO images comprising enface images. 
     * The computer tracks the target according to the plurality of SLO images. 
     * The computer aims the laser beam according to the OCT images and instructs the laser device to fire the laser beam. 
     * The SLO device generates the SLO images while the laser device fires the laser beam. 
     * The OCT device directs the OCT imaging beam along the OCT imaging beam path towards a calibration pattern, receives the OCT imaging beam reflected from the calibration pattern, and generates an OCT image of the calibration pattern from the reflected OCT imaging beam. The SLO device directs the SLO imaging beam along the SLO imaging beam path towards the calibration pattern, receives the SLO imaging beam reflected from the calibration pattern, and generates an SLO image of the calibration pattern from the reflected SLO imaging beam. The computer determines one or more differences between the OCT image and the SLO image of the calibration pattern, and calculates one or more correction parameters to compensate for the differences between the OCT image and the SLO image of the calibration pattern. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    illustrates an example of an ophthalmic surgical system that can image and treat a target in an eye, according to certain embodiments; 
         FIG.  2    illustrates another example of an ophthalmic surgical system that can image and treat a target in an eye, according to certain embodiments; 
         FIG.  3    illustrates an example of a calibration pattern that may be used by the system(s) of  FIGS.  1  and/or  2    to register OCT, laser, and/or SLO devices, according to certain embodiments; 
         FIG.  4    illustrates an example of a method for imaging and treating a target in an eye that may be performed by the system(s) of  FIGS.  1  and/or  2   , according to certain embodiments; 
         FIG.  5    illustrates an example of a method for imaging and treating a target in an eye that may be performed by the system(s) of  FIGS.  1  and/or  2   , according to certain embodiments; and 
         FIG.  6    illustrates an example of a method for registering OCT and SLO devices that may be performed by the system(s) of  FIGS.  1  and/or  2   , 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. 
     Known image-guided laser beam delivery systems require registration of imaging and laser beam systems to precisely guide the beam. However, known registration techniques are complicated and often do not provide sufficient levels of accuracy. Moreover, inherent variations of the optical properties of eyes make reliable registration difficult. 
     Accordingly, embodiments of the systems described herein include: (1) an imaging system with an optical coherence tomography (OCT) device that directs an imaging beam towards the target to generate an image of the target; and (2) a treatment system that directs a laser beam to the target to fragment the target. The imaging and laser beams share a laser-OCT xy-scanner to automatically register the beams. In certain embodiments, the imaging system also includes a scanning laser ophthalmoscope (SLO) device with an SLO xy-scanner. The laser-OCT and SLO xy-scanners may be registered using a calibration pattern. 
       FIG.  1    illustrates an example of an ophthalmic surgical system  10   a  that can image and treat a target in an eye, according to certain embodiments. In the example, the target is a vitreous eye floater or the shadow it casts on the retina. In the example, an axis of the eye (e.g., visual or optical) defines a z-axis, which in turn define x- and y-axes orthogonal to each other and to the z-axis. X- and y-axes define xy-planes within the eye. X-, y-, and z-directions and locations are relative to the x-, y-, and z-axes, respectively. 
     In the example, system  10   a  includes a treatment system (which comprises a laser device  20 ), an imaging system (which comprises optical coherence tomography (OCT) device  22 ), a beam combining and alignment device  23 , a laser-OCT xy-scanner  24 , optical elements  26 , and a computer  38 , coupled as shown. Laser device  20  includes a laser  30  and lenses  32 ,  34 , coupled as shown. Optical components includes beam combining and alignment device  23  and lenses  32 ,  34 ,  40 ,  42 , and  46 , coupled as shown. Computer  38  includes logic  52 , memory  54  (which stores a computer program  55 ), a user interface (IF)  56 , and a display  58 , coupled as shown. 
     As an example of operation, OCT device  22  directs an OCT imaging beam along an imaging beam path towards the eye, receives the OCT imaging beam reflected from the eye, and generates OCT images from the reflected OCT imaging beam. Laser device  20  directs a laser beam along a laser beam path towards the target. Beam combining and alignment device  23  combines and co-aligns the OCT imaging beam and the laser beam. Laser-OCT xy-scanner  24  receives the OCT imaging beam from the imaging system, directs the OCT imaging beam along the imaging beam path towards the target, and scans the OCT imaging beam in an xy-plane in the eye. Laser-OCT xy-scanner  24  also receives the laser beam from the laser device, directs the laser beam along the laser beam path co-aligned with the imaging beam path towards the target, and scans the laser beam in an xy-plane in the eye. Computer  38  sends instructions to the OCT device and the laser device. 
     Turning to the treatment system, laser  30  of laser device  22  generates a laser beam with any suitable wavelength, e.g., in a range from 400 nm to 2000 nm. Laser device  22  delivers laser pulses at any suitable repetition rates ranging from, but not limited to, 1 hertz (Hz) to several hundreds of kilohertz (kHz). A laser pulse may have any suitable pulse duration (e.g., ranging from, but not limited to, a nanosecond (ns) to 20 femtoseconds (fs)), any suitable pulse energy (e.g., 1 microjoule (µJ) to 10 millijoule (mJ)), and a focal point of any suitable size (e.g., ranging from 3 to 20 microns (µm), such as 7 µm). Lenses  32  and  34  are used to adjust the focus position of the laser beam within tissue, such as eye tissue. 
     OCT device  22  may be any suitable device that utilizes optical coherence tomography to generate images, e.g., a swept-source OCT (SS-OCT), line-field OCT, full-field OCT, or spectral-domain OCT (SD-OCT) device. 
     Beam combining and alignment device  23  combines and co-aligns the OCT imaging beam and the laser beam. Beam combining and alignment device  23  may be any suitable device that directs and aligns laser beams along a desired beam path, e.g., a beam combiner or a dichroic mirror (DM). In certain embodiments, beam combining and alignment device  23  may be mounted on a two-axis kinematic mount. Beam combining and alignment device  23  is positioned such that the laser and imaging beams are co-aligned, and then the mount is secured to maintain the alignment. 
     Laser-OCT xy-scanner  24  scans the laser and imaging beams transversely in xy-directions. Examples of scanners include a galvo scanner (e.g., a pair of galvanometrically-actuated scanner mirrors that can be tilted about mutually perpendicular axes), an electro-optical scanner (e.g., an electro-optical crystal scanner) that can electro-optically steer the beam, or an acousto-optical scanner (e.g., an acousto-optical crystal scanner) that can acousto-optically steer the beam. Laser-OCT xy-scanner  24  scans the OCT imaging beam and the laser beam in an xy-plane in the eye in any suitable manner. For example, xy-scanner  24  may scan a beam (e.g., the OCT imaging beam) in a continuous manner. As another example, xy-scanner  24  may scan a beam (e.g., the laser beam) in a stepwise manner, e.g., scanning when the laser device is not firing the laser beam and ceasing scanning when the laser device is firing the laser beam. 
     OCT device  22  and laser device  20  share xy-scanner  24 , allowing for co-registration between the OCT imaging and treatment beams. That is, xy-scanner  24  receives the imaging beam from the imaging system and directs the imaging beam along the imaging beam path towards the target, and receives the laser beam from the laser device and directs the laser beam along the laser beam path co-aligned with the imaging beam path towards the target. The OCT imaging and treatment beams share the same path through the optics of the system and the eye, so are affected by the same optical properties and distortions along the beam path. Thus, if the imaging and treatment beams are aligned prior to xy-scanner  24 , they are automatically aligned at the target location. This enables accurate and precise delivery of the laser beam to the target location identified using OCT images. 
     Optical elements includes beam combining and alignment device  23  and lenses  32 ,  34 ,  40 ,  42 , and  46 , coupled as shown. In general, an optical element can act on (e.g., transmit, reflect, refract, diffract, collimate, condition, shape, focus, modulate, and/or otherwise act on) a laser beam. Examples of optical elements include a lens, prism, mirror, diffractive optical element (DOE), holographic optical element (HOE), and spatial light modulator (SLM). In the example, lens  40  collimates the beam from OCT device  22  to and from beam combining and alignment device  23 . Beam combining and alignment device  23  directs beams from OCT device  22  and laser device  20  to xy-scanner  24  and directs beams reflected from the eye back to OCT device  22 . Lenses  32  and  34  collimate the beam from laser  30  and can also adjust the focus of a laser beam in the eye. Lens  42  and objective lens  46  collimate and focus beams toward the eye. 
     Computer  38  sends instructions to the OCT device and the laser device. Computer  38  may utilize computer programs  55  to perform operations. Examples of computer programs  55  include target imaging, target tracking, image processing, and target evaluation. In certain embodiments, computer  26  may use an image processing program  55  to perform image processing on an image, e.g., analyze the digital information of the image to extract information from the image. In certain embodiments, computer  26  performs image processing to analyze an image of a target or a target’s shadow (i.e., “target shadow”) to obtain information about the target. Localized opacities in the vitreous, such as floaters, can affect vision quality when they are in the path of light and cast a shadow onto the retina. Hence, the target shadow can provide useful information about clinical significance of the floater or other opacity, e.g., the density or contrast of the floater shadow may indicate the level of vision obstruction caused by the floater. In certain embodiments, computer  26  may use a floater shadow tracking program  55  to track floaters. Moving shadows may indicate the presence of symptomatic floaters that cause vision obstruction, rather than other vitreous structures or features that do not cause sufficient vision obstruction. 
       FIG.  2    illustrates another example of an ophthalmic surgical system  10   b  that can image and treat a target in an eye, according to certain embodiments. In the example, system  10   b  is substantially similar to system  10   a  of  FIG.  1   , except that a scanning laser ophthalmoscope (SLO) device  60  has been added to the imaging system. In the example, SLO device  60  includes a laser  62 , an SLO xy-scanner  64 , an SLO detector  66 , and a beamsplitter  68 , coupled as shown. SLO detector includes a photodetector (e.g., photodiode PD)  70 , lens  72 , and lens  74 , coupled as shown. Analogous components of system  10   b  are as described with reference to  FIG.  1   . 
     In an example of operation, OCT device  22  directs an OCT imaging beam along an OCT imaging beam path towards the eye, receives the OCT imaging beam reflected from the eye, and generates OCT images from the reflected OCT imaging beam. SLO device  60  directs an SLO imaging beam along an SLO imaging beam path towards the eye, receives the SLO imaging beam reflected from the eye, and generates SLO images from the reflected SLO imaging beam. SLO xy-scanner  64  scans the SLO imaging beam in an xy-plane in the eye. Laser device  20  directs a laser beam along a laser beam path towards the target. Laser-OCT xy-scanner  24  receives the OCT imaging beam from the imaging system, directs the OCT imaging beam along the imaging beam path towards the target, and scans the OCT imaging beam in an xy-plane in the eye. Laser-OCT xy-scanner  24  also receives the laser beam from the laser device, directs the laser beam along the laser beam path co-aligned with the imaging beam path towards the target, and scans the laser beam in an xy-plane in the eye. Computer  38  sends instructions to OCT device  22  and laser device  20 . 
     Turning to the components, laser  62  of SLO device  60  generates any suitable SLO imaging beam, such as a laser beam with a visible or near-infrared wavelength. SLO xy-scanner  64  may be an xy-scanner as described with respect to laser-OCT xy-scanner  24 . Beamsplitter  68  directs outgoing beams from laser  62  to SLO xy-scanner  64  and incoming reflected beams from the eye via SLO xy-scanner  64  to SLO detector  66 . Lens  74  focuses the beam to confocal aperture  72 , and the focused beam is directed to photodetector  70 . Photodetector  70  detects light and generates a signal corresponding to the light. The signal may be used to generate SLO images. 
     OCT device  22  and SLO device  60  each provide different imaging characteristics. In certain embodiments, OCT device  22  can provide higher resolution two-dimensional (2D) and three-dimensional (3D) imaging over smaller regions. In certain embodiments, SLO device  60  can provide larger field of view (FOV) imaging and a faster 2D imaging refresh rate than that of 3D imaging by OCT device  22 . For example, SLO device  60  may provide a 40 degrees or greater FOV and a 20 to 40 hertz (HZ) or greater refresh rates, while OCT device  22  may provide a 10 degrees FOV and a 10 to 20 Hz 3D refresh rate. The larger FOV of around 40 degrees allows for imaging a wider region of vitreous and retina in the eye, including the arcades to better detect floaters or other vitreous opacities that move. Moreover, target shadows may often yield higher contrast, clearer images than the targets themselves in SLO imaging. In addition, faster SLO refresh rates allow for more effective tracking of the target (e.g., by tracking the target shadow, as described above) and can yield shorter treatment times. 
     In certain embodiments, laser-OCT xy-scanner  24  and SLO xy-scanner  64  can scan concurrently, which allows for efficient concurrent operation of OCT device  22  and SLO device  60 . For example, OCT device  22  determines the z-location of the target relative to the z-axis, while SLO device  60  determines the xy-location of the target relative to an xy-plane. As another example, OCT device  22  determines the xyz-location of the target relative to the x, y, and z-axes, while SLO device  60  provides real-time video of the eye. As another example, computer  38  can track the target according to SLO images, while aiming the laser beam according to the OCT images and instructing the laser device to fire the laser beam. As another example, SLO device  60  generates SLO images while laser device  20  fires the laser beam. As another example, SLO device  60  may detect unwanted motion of the eye during treatment and be used to shut off treatment. 
       FIG.  3    illustrates an example of a calibration pattern  80  that may be used by system(s)  10  ( 10   a ,  10   b ) of  FIGS.  1  and/or  2    to register OCT, laser, and/or SLO devices, such as OCT device  22  and SLO device  60 , according to certain embodiments. For example, xy-scanner  24  of OCT device  22  and xy-scanner  64  of SLO device  60  may be registered. 
     Calibration pattern  80  may be any suitable pattern that can test the xy-scanning of an imaging device. Examples of such patterns include a checkerboard, concentric circles, concentric circles with radial lines or sectors, etc. Calibration pattern  80  may be disposed upon any suitable rigid medium. In certain embodiments, the pattern may be printed on an artificial eye to provide realistic scanning of a shape that represents the eye. 
     In an example of operation, OCT device  22  directs the OCT imaging beam along the imaging beam path towards calibration pattern  80 , receives the OCT imaging beam reflected from calibration pattern  80 , and generates an OCT image of calibration pattern  80  from the reflected OCT imaging beam. SLO device  60  directs the SLO imaging beam along the imaging beam path towards calibration pattern  80 , receives the SLO imaging beam reflected from calibration pattern  80 , and generates an SLO images of calibration pattern  80  from the reflected SLO imaging beam. 
     Continuing the example of operation, computer  38  determines differences between the OCT image and the SLO image of calibration pattern  80 , and calculates correction parameters that compensate for the differences to register OCT device  22  and SLO device  60 . For example, computer  38  determines the position of laser-OCT xy-scanner  24  that yields the OCT beam at an xy-location of calibration pattern  80 , and the position of SLO xy-scanner  64  that yields the SLO beam at the same xy-location of calibration pattern  80 . Computer  38  then calculates the differences between the positions to determine correction parameters that compensate for the differences. 
     In the illustrated example, calibration pattern  80  is used to register OCT device  22  and SLO device  60 . However, calibration pattern  80  may be used for any suitable calibration. In certain embodiments, calibration pattern  80  is used to calibrate laser device  20  and OCT device  22 . In the embodiments, laser device  20  directs the laser beam towards a laser xy-location of calibration pattern  80  to yield a mark at the laser xy-location. OCT device  22  directs the OCT imaging beam towards calibration pattern  80 , receives the OCT imaging beam reflected from calibration pattern  80 , and generates an OCT image of the mark on calibration pattern  80  from the reflected OCT imaging beam. Computer  38  performs a registration procedure by determining differences between the OCT xy-location of the mark on the OCT image and the laser-xy-location of the mark, and calculating correction parameters to compensate for the differences. 
     Computer  38  may perform the registration procedure at any suitable point. For example, registration may be performed at production, after transporting the system to a new location, at the customer location, and/or periodically throughout the life of the device. Computer  38  may perform the registration procedure under any suitable conditions. For example, computer  38  performs the registration procedure while laser-OCT xy-scanner  24  is scanning in a continuous manner. As another example, computer  38  performs the registration procedure while laser-OCT xy-scanner  24  is scanning in a stepwise manner. 
       FIG.  4    illustrates an example of a method for imaging and treating a target in an eye that may be performed by system(s)  10  ( 10   a ,  10   b ) of  FIGS.  1  and/or  2   , according to certain embodiments. The method starts at step  108 , where OCT and laser devices are registered. In certain embodiments, to register the devices, the laser device directs a laser beam along towards an xy-location of a calibration pattern to yield a mark at the xy-location. The OCT device directs the OCT imaging beam towards the calibration pattern and generates an OCT image of the mark on the calibration pattern from the reflected OCT imaging beam. A computer may perform a registration procedure by determining differences between the OCT xy-location of the mark on the OCT image and the laser xy-location of the mark, and calculating correction parameters that compensate for the differences. 
     The OCT device directs an OCT imaging beam toward the eye at step  110 . The xy-scanner scans the OCT imaging beam in the eye in a continuous manner at step  112 . The interior of the eye reflects the OCT imaging beam. The OCT device detects the reflected OCT imaging beam and generates OCT images from the reflected beam at step  114 . 
     The laser device directs a laser beams towards the target at step  116 . The xy-scanner scans the laser beam in the eye in a stepwise manner at step  120 . The xy-scanner may scan in a stepwise manner by scanning when the laser device is not firing the laser beam and ceasing scanning when the laser device is firing the laser beam. Since the OCT and laser devices share the xy-scanner, if the imaging and treatment beams are co-aligned prior to the xy-scanner, the two beams are automatically registered. (If there is a misalignment between the beams prior to the xy-scanner, a correction parameter obtained from registering the OCT and laser devices can be applied to compensate for the misalignment.) The target is fragmented at step  122 . 
       FIG.  5    illustrates an example of a method for imaging and treating a target in an eye that may be performed by system(s)  10  ( 10   a ,  10   b ) of  FIGS.  1  and/or  2   , according to certain embodiments. The method starts at steps  210  and  220 . Steps  210 ,  212 , and  214  may be performed concurrently with steps  220 ,  222 , and  224  to concurrently generate OCT and SLO images. The OCT and SLO devices use different scanners, which facilitates concurrent generation of the OCT and SLO images. 
     The OCT device directs an OCT imaging beam toward the eye at step  210 . The laser-OCT xy-scanner scans the OCT imaging beam in the eye at step  212 . The OCT device detects the reflected OCT imaging beam and generates OCT images from the reflected beam at step  214 . The SLO device directs an SLO imaging beam toward the eye at step  220 . The SLO xy-scanner scans the SLO imaging beam in the eye at step  222 . The SLO device detects the reflected SLO imaging beam and generates SLO images from the reflected beam at step  224 . 
     The computer tracks the target using the SLO images at step  230 . In certain embodiments, the SLO device has a faster frame refresh rate and/or wider field of view than the OCT device, so is better able to track a moving target. The laser device aims the laser beam at the target using the OCT images at step  232 . The OCT and laser devices share an xy-scanner, allowing for co-registration between the imaging and treatment beams. (If appropriate, correction parameters may be applied to compensate for a misalignment or other error between any of the components of system  10 , e.g., the SLO, OCT, and/or laser device.) The target is fragmented at step  234 . 
       FIG.  6    illustrates an example of a method for registering OCT and SLO devices that may be performed by system(s)  10  ( 10   a ,  10   b ) of  FIGS.  1  and/or  2   , according to certain embodiments. In certain embodiments, the OCT and SLO devices use different scanners, so the method may be performed to register the scanners of the devices. The method starts at steps  310  and  320 . Steps  310 ,  312 , and  314  may be performed concurrently with steps  320 ,  322 , and  324  to concurrently generate OCT and SLO images of a calibration pattern. 
     The OCT device directs an OCT imaging beam toward the calibration pattern at step  310 . The laser-OCT xy-scanner scans the OCT imaging beam across the calibration pattern at step  312 . The OCT device detects the reflected OCT imaging beam and generates OCT images of the calibration pattern from the reflected beam at step  314 . The SLO device directs an SLO imaging beam toward the calibration pattern at step  320 . The SLO xy-scanner scans the SLO imaging beam across the calibration pattern at step  322 . The SLO device detects the reflected SLO imaging beam and generates SLO images of the calibration pattern from the reflected beam at step  324 . 
     The computer determines differences between the OCT and SLO images of the calibration pattern at step  330 . The computer determines correction parameters that compensate for the differences at step  332  in order to register the OCT and SLO devices. For example, the computer determines the position of the laser-OCT xy-scanner that yields the OCT beam at an xy-location of the calibration pattern, and the position of the SLO xy-scanner that yields the SLO beam at the same xy-location of the calibration pattern. The computer calculates the differences between the positions to determine correction parameters that compensate for the differences. 
     A component (such as the control computer) 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).