Patent Publication Number: US-2015085254-A1

Title: Micro-Display Based Slit Lamp Illumination System

Description:
TECHNICAL FIELD 
     The present disclosure is generally directed to ophthalmic systems for use in diagnosing and treating conditions of the eye, and more specifically to illumination systems and methods for ophthalmic systems. 
     BACKGROUND 
     A conventional slit lamp is an instrument consisting of a high-intensity light source. The high-intensity light source can be focused to shine a beam of light into a patient&#39;s eye. The beam of light is often focused to shine a desired light pattern into the patient&#39;s eye, such as a thin slit-shaped sheet of light. 
     Slit lamps are typically used in ophthalmic illumination systems to allow a practitioner to diagnose and treat conditions of the eye, e.g., by enabling a practitioner to view the patient&#39;s eye. For example, a slit lamp may be a component of a clinical bio-microscope used to facilitate an examination of structures within a patient&#39;s eye, including the eyelid, retina, sclera, conjunctiva, iris, lens and cornea. 
     A clinical bio-microscope is typically composed of a viewing system that is co-pivotal with a slit lamp to allow various angles of viewing and angles of illumination to a patient&#39;s eye. For example, a relatively oblique angle of illumination may be chosen to enhance the surface details and texture of a patient&#39;s eye by showing a shadowing on the distal edge of the subject. In contrast, a relatively direct coaxial angle of illumination may be chosen to more accurately show color, size and relative position of a subject (e.g., a retina) in relation to other anatomy. A relatively direct coaxial angle of illumination also may appear to flatten structures that would otherwise appear to be more three-dimensional when illuminated at a relatively severe angle. 
     Several factors can affect the quality of eye visualization, including opaque and highly reflective cornea tissue, iris color and other biological variables. As such, conventional slit lamps typically include orientation and angle settings (e.g., settings for various slit sizes and shapes), a rotating filter wheel (also known as a color wheel filter), and other mechanisms to allow for exposure adjustment control in an illuminated image of a patient&#39;s eye. In many existing ophthalmic illumination systems, however, slit lamp adjustment controls are limited, which can reduce the achievable quality of an illuminated image of a patient&#39;s eye that can be viewed by a practitioner or photographed. 
     SUMMARY 
     A micro-display based slit lamp illumination system is provided. A first optical element is configured to generate a micro-display image including an illuminated area. A second optical element is configured to receive the micro-display image, and focus the micro-display image upon an eye to be examined, wherein light is reflected from the eye as a result of the illuminated area. The first optical element may be a micro-display projector and include one of a liquid crystal on silicon (LCoS), digital-micro-mirror (DMD) or micro-electro-mechanical systems (MEMS) micro-scanner and one of a visible (RGB) light-emitting diode (LED) or laser light source or invisible (infrared, ultraviolet) LED or laser light source. 
     In accordance with an embodiment, a controller may be configured to receive a parameter for generating the micro-display image, wherein the parameter is related to one of a color, shape or size of the illuminated area. The controller may transmit a command based on the parameter to the first optical element. 
     In accordance with an embodiment, the illuminated area may be one of a slit-shaped, round or polygonal-shaped area, and the micro-display image may include a plurality of illuminated areas. 
     In accordance with an embodiment, the micro-display image may include concurrent information. The concurrent information may relate to measurement information, patient data, a treatment parameter, a preoperative image or a treatment plan. 
     These and other advantages of the invention will be apparent to those of ordinary skill in the art by reference to the following detailed description and the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a conventional slit-lamp system; 
         FIG. 2  shows a micro-display based slit-lamp illumination system in accordance with an embodiment; 
         FIG. 3  shows an image generated by a micro-display projector onto a patient&#39;s eye in accordance with an embodiment; 
         FIG. 4  shows an image generated by a micro-display based slit-lamp illumination system in accordance with an embodiment; 
         FIG. 5  shows an image generated by a micro-display based slit-lamp illumination system in accordance with an embodiment; 
         FIG. 6  shows an image generated by a micro-display based slit-lamp illumination system in accordance with an embodiment; 
         FIG. 7  shows an image generated by a micro-display based slit-lamp illumination system in accordance with an embodiment; 
         FIG. 8  shows an image generated by a micro-display based slit-lamp illumination system in accordance with an embodiment; 
         FIG. 9  is a flowchart of a method of micro-display based slit lamp illumination in accordance with an embodiment; 
         FIG. 10  is a high-level block diagram of an exemplary computer that may be used for the various embodiments herein. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a conventional slit-lamp system. A conventional slit-lamp illumination system typically includes a halogen lamp or white LED light source, a slit adjustment mechanism, optical relay, filter wheel, slit rotation prism assembly and exit (turning) prism/mirror. For example, system  100  comprises a primary light source  110 , a mirror  120  and a beam splitter  165 . Primary light source  110  generates light  105  which is directed via color wheel filter  115  and mirror  120  toward a patient&#39;s eye  130 . The light strikes eye  130  and is reflected, generating reflected light  140 . Reflected light  140  passes through beam splitter  165  and propagates toward a practitioner&#39;s eye  190 , allowing the practitioner to view structures within patient&#39;s eye  130 . Beam splitter  165  is typically adapted to allow a significant amount of reflected light  140  from patient&#39;s eye  130  to pass through depending on the application. 
     Primary light source  110  comprises a conventional slit lamp. Many conventional slit-lamp-based illumination systems use a high-intensity/high-pressure light source, such as a halogen light source that produces and channels white light to the slit lamp. The use of white light does not permit a practitioner to control with precision the color of the light that enters the slit lamp, and therefore limits the range of observations that can be made by the practitioner. As such, it is sometimes advantageous to observe certain structures of the eye, and/or certain medical conditions, using selected colors of light. 
     Typical illumination systems use one or more color filters to control the color of light delivered to the eye in order to facilitate the observation of certain aspects of the eye that may be difficult to visualize under white light. For example, color wheel filter  115  may be used to produce red, blue, or green light, to remove infrared light, or to otherwise select the color of light  105  that passes through to mirror  120 . However, even with the use of filters, such as color wheel filter  115 , the practitioner is limited by the filters currently available and therefore may not be able to achieve a desired level of precision in the selection of the color of light used. 
       FIG. 2  shows a micro-display based slit lamp illumination system in accordance with an embodiment. System  200  comprises a micro-display projector  210  and a mirror  220 . In an embodiment, micro-display projector  210  is used in place of a conventional slit-lamp illumination assembly having a primary light source, such as primary light source  110  in  FIG. 1 . 
     In system  200 , micro-display projector  210  generates a micro-display image  205  including an illuminated area which is directed by mirror  220  toward a patient&#39;s eye  230 . Micro-display image  205  is displayed upon patient&#39;s eye  230  and is reflected at least in part based on the illuminated area, generating reflected light  240 . Reflected light  240  propagates toward a practitioner&#39;s eye  290 , allowing the practitioner to view structures within patient&#39;s eye  230 . 
     Micro-display projector  210  may be any type of micro-display or pico projector comprising an optical engine (e.g., an illumination source, modulator and projection optics). For example, micro-display projector  210  may be a stand-alone projector or a projector that is integrated into another device, such as a mobile device (e.g., a mobile phone) or a notebook computer. 
     Micro-display projector  210  may include one of a liquid crystal on silicon (LCoS), digital-micro-mirror device (DMD), 2-D micro-electro-mechanical systems (MEMS) or 2-D X/Y galvanometer set micro-scanner for generating an image. Micro-display projector  210  also may comprise relay optics (e.g., to illuminate a micro-display with an illumination area dimension matching the micro-display size), and a collimation or projection lens. 
     Further, micro-display projector  210  may include one or more sources of visible and/or invisible illumination to be operable to form, e.g., an infrared or color image projection. The one or more sources of visible and/or invisible illumination may include a halogen lamp, a white light emitting diode (LED), one or more coaxial LEDs (e.g., red, green, blue, amber or near-infrared LEDs) or one or more coaxial lasers (e.g., red-green-blue (RGB) or near-infrared lasers). In an embodiment, an exemplary light source for micro-display projector  210  may have an illumination range of around 10-200 lumens. One skilled in the art will note that micro-display projector  210  may include several other elements, and that the micro-display projector features and components discussed herein are merely illustrative and, therefore, are not intended to be exhaustive. 
     In an embodiment, micro-display projector  210  generates micro-display projection  205  such that an image including an illuminated area is directed by mirror  220  for display upon patient&#39;s eye  230 . For example, micro-display projector  210  may generate micro-display projection  205  to project one or more slit-shaped, round or polygonal-shaped areas or channels of white or colored light upon patient&#39;s eye  230 . As such, micro-display projector  210  can be configured, e.g., via a command received from controller  295 , to generate micro-display projections that allow for a wide range of observations to be made by a practitioner. 
     In an embodiment, controller  295  may be configured to receive user inputs via control switches, knobs, or a GUI interface (e.g. a touch-screen display or LCD with a mouse/trackpad interface), and transmit one or more commands to micro-display projector  210  to generate a micro-display projection  205  based on the one or more received user inputs. Controller  295  also may transmit one or more commands to micro-display projector  210  to adjust the color, brightness and timing of micro-display projection  205  based on one or more user inputs. Controller  295  also may be configured to receive inputs from one or more external sources (e.g. a camera flash trigger or a computer processing real-time slit-lamp video) and transmit commands to projector  210 . 
     As such, micro-display projector  210  can generate a micro-display image  205  including illuminated areas having selected colors of light, thereby emulating the effect of color wheel filter  115 , shown in  FIG. 1 . For example, micro-display image  205  may include an illuminated area of red, blue, green, infrared or ultraviolet light. However, unlike color wheel filter  115 , micro-display projector  210  can be configured to generate micro-display projection  205  to achieve desired levels of precision in the selection of the color (e.g., color gradation) and intensity of light used. 
     In addition, micro-display projector  210  may be configured to emulate the operation of a conventional slit-lamp-based illumination system by allowing for various angles of viewing and angles of illumination to patient&#39;s eye  230 . For example, micro-display projector  210  may be configured to swivel about an image plane or to scan the micro-display projection  205  of an image across a desired range (e.g., across a 180 deg range). 
       FIG. 3  shows an image generated by a micro-display projector onto a patient&#39;s eye in accordance with an embodiment. Micro-display image  300  includes an illuminated (slit-shaped) area  310  generated by micro-display projector  210  and directed by mirror  220  (shown in  FIG. 2 ) onto patient&#39;s eye  330 . In an embodiment, micro-display projector  210  also may generate concurrent information  320  that is integrated into micro-display image  300 . Alternatively, all or part of concurrent information  320  may be received from a source external to micro-display projector  210  (e.g., from controller  295 , or a source other than controller  295 ). 
     For example, concurrent information  320  may include visual information received or generated by micro-display projector  210 , including any type of image or data that may be projected onto a patient&#39;s eye  330 . Concurrent information  320  may include patient information, the current time and date, or other information that may be of use in a clinical environment. In another example, concurrent information  320  may measurement information regarding micro-display image  300 , such as a measurement axis, distance, area, scale or grid. Measurement information also may include a current illumination area diameter, current slit width, inter-slit spacing, current filter choice, micrometer scale labeling, or circle/ellipse radii, ratios and areas. 
     When illumination system  200  is used in conjunction with therapy systems including laser systems and other equipment, concurrent information  320  may include one of a treatment parameter or a preoperative image, treatment plan, an aiming beam pattern or a treatment beam target indicator. For example, concurrent information  320  may be received from a laser system console to include information regarding treatment laser parameters, such as, e.g., power, spot-size and spacing for display as part of micro-display projection  300 . 
     In accordance with various embodiments, micro-display projector  210  and controller  295  may be configured to create images corresponding to clinically useful slit-lamp settings, such as those shown in  FIGS. 4-8  and described below. Micro-display projector  210  and controller  295  also may be configured to create images corresponding to any combination of the slit-lamp settings shown in  FIGS. 4-8 . For example, controller  295  may receive a parameter for generating a micro-display projection of an image having an illuminated area, wherein the parameter is related to one of a color, shape or size of the illuminated area, and transmit a command based on the parameter to micro-display projector  210 . 
       FIG. 4  shows an image generated by a micro-display based slit lamp illumination system in accordance with an embodiment. Image  400  illustrates a micro-display image  205  including an illuminated circular-shaped area  402 . For example, area  402  may be between 0.2 mm to &gt;=8 mm in diameter (e.g., based on a 20 mm maximum for a typical eye surface area). In an embodiment, the diameter of area  402  may be continuously adjustable, e.g., in response to commands transmitted from controller  295  to micro-display projector  210 . In another embodiment, area  402  may be user-adjustable based on color, including white (unfiltered), blue (“cobalt blue”), green (red-free), 10% intensity (grey) or other illumination settings of micro-display projector  210 . For example, a user may have discrete control of each color channel of area  402 . 
     As such, at controller  295  color gradation may be selectable via preset red-green-blue (RGB) intensity settings or may be continuously variable based on user inputs. 
       FIG. 5  shows an image generated by a micro-display based slit lamp illumination system in accordance with an embodiment. Image  500  illustrates a micro-display image  205  including an illuminated slit-shaped area  502 . For example, area  502  may be between 0.2 mm to &gt;=8 mm in length (e.g., based on a 20 mm maximum for a typical eye surface area), continuously adjustable between 0 mm to up to &gt;=8 mm in width (20 mm maximum) and continuously adjustable (e.g., +/−90 deg) in orientation. As such, the slit may be centered (coaxial) or offset within a coaxial field-of-view. 
       FIG. 6  shows an image generated by a micro-display based slit lamp illumination system in accordance with an embodiment. Image  600  illustrates a micro-display image  205  including illuminated double slit-shaped areas  602  and  604 . Double slit-shaped areas  602  and  604  may have adjustable parameters similar to those of area  502  above. For example, areas  602  and  604  each may be between 0.2 mm to &gt;=8 mm in length (e.g., based on a 20 mm maximum for a typical eye surface area), continuously adjustable between 0 mm to up to &gt;=8 mm in width (20 mm maximum) or continuously adjustable (e.g., +/−90 deg) in orientation. In addition, areas  602  and  604  may be adjustable with regard to inter-slit spacing, e.g., from 0 mm up to &gt;=8 mm (e.g., for a 20 mm maximum area width). For example, image  600  may include concurrent information  606  related to real-time spacing offset information (i.e., measurement information) with regard to inter-slit spacing. 
       FIG. 7  shows an image generated by a micro-display based slit lamp illumination system in accordance with an embodiment. Image  700  illustrates a micro-display image  205  including micrometer (e.g., reticle) areas  702  and  704  and grid  706 , wherein the scale size, major and minor units of the areas are adjustable. For example, areas  702  and  704  and grid  706  may be useful for various clinical measurements, including pupil diameter, anterior chamber angle depth (non-gonioscopic), depth of foreign-bodies in cornea, gonioscopic measurement of iridocorneal angles, measurement of tear film meniscus height and rim tissue width around an optic nerve head. 
       FIG. 8  shows an image generated by a micro-display based slit lamp illumination system in accordance with an embodiment. Image  800  illustrates a micro-display image  205  including circle/ellipse contours  802  and  804  and concurrent information  806  related to major and minor radii of contours  802  and  804 . For example, major and minor radii may be adjusted (e.g., via controller  295 ) for measuring pupil diameter or a cup-to-disc ratio of optic nerve head. Contours  802  and  804  and concurrent information  806  may be useful for various clinical measurements, including pupil diameter, anterior chamber angle depth (non-gonioscopic), depth of foreign-bodies in cornea, gonioscopic measurement of iridocorneal angles, measurement of tear film meniscus height and rim tissue width around an optic nerve head. 
       FIG. 9  is a flowchart of a method of micro-display based slit lamp illumination in accordance with an embodiment.  FIG. 9  is discussed below with reference also to  FIG. 2 . 
     At step  910 , a parameter for generating the micro-display image is received. Referring to  FIG. 2 , controller  295  may be configured to receive a parameter for generating the micro-display image, wherein the parameter is related to one of a color, shape or size of the illuminated slit image. In an embodiment, controller  295  may be configured to receive a parameter for generating the micro-display image to further include concurrent information relating to patient data, a treatment parameter, a preoperative image, or a treatment plan. 
     At step  912 , a command based on the parameter is transmitted to micro-display projector  210 . Referring to  FIG. 2 , controller  295  transmits a command based on the parameter to micro-display projector  210 , wherein micro-display projector  210  generates micro-display image  205  in accordance with the command. 
     At step  914 , a first optical element is configured to generate an image including an illuminated area. For example, the first optical element may be a micro-display projector including one of a liquid crystal on silicon (LCoS), digital-micro-mirror (DMD) or micro-electro-mechanical systems (MEMS) micro-scanner and one of a light-emitting diode (LED) or red-green-blue (RGB) laser light source. Referring to  FIG. 2 , micro-display projector  210  generates micro-display image  205  including an illuminated area (e.g., in accordance with the command received from controller  295 ). For example, the illuminated area may be a slit-shaped, round or polygonal-shaped area. 
     At step  916 , a second optical element is configured to receive the micro-display image. Referring to  FIG. 2 , mirror  220  receives micro-display image  205  generated by micro-display projector  210 . 
     At step  918 , the second element is configured to direct the projection of the image upon an eye to be examined, wherein light is reflected from the eye as a result of the image. Referring to  FIG. 2 , mirror  220  directs the micro-display image toward a patient&#39;s eye  230 . Micro-display image  205  is displayed upon eye  230 , and the image is reflected, generating reflected light  240  which propagates toward a practitioner&#39;s eye  290 , allowing the practitioner to view structures within the patient&#39;s eye  230 . For example, the reflected light may include an image of structures within patient&#39;s eye  230  due to an illuminated area of micro-display image  205 . 
     As such, a micro-display slit-lamp illumination system as disclosed herein may serve as a replacement for a traditional slit-lamp illuminator. Moreover, the micro-display slit-lamp illumination system can extend the capabilities of a traditional slit-lamp illuminator from simple illumination to quantification of observed tissue, as well as presentation of additional clinically relevant information. 
     Systems, apparatus, and methods described herein may be implemented using digital circuitry, or using one or more computers using well-known computer processors, memory units, storage devices, computer software, and other components. Typically, a computer includes a processor for executing instructions and one or more memories for storing instructions and data. A computer may also include, or be coupled to, one or more mass storage devices, such as one or more magnetic disks, internal hard disks and removable disks, magneto-optical disks, optical disks, etc. 
     Systems, apparatus, and methods described herein may be implemented using computers operating in a client-server relationship. Typically, in such a system, the client computers are located remotely from the server computer and interact via a network. The client-server relationship may be defined and controlled by computer programs running on the respective client and server computers. 
     Systems, apparatus, and methods described herein may be used within a network-based cloud computing system. In such a network-based cloud computing system, a server or another processor that is connected to a network communicates with one or more client computers via a network. A client computer may communicate with the server via a network browser application residing and operating on the client computer, for example. A client computer may store data on the server and access the data via the network. A client computer may transmit requests for data, or requests for online services, to the server via the network. The server may perform requested services and provide data to the client computer(s). The server may also transmit data adapted to cause a client computer to perform a specified function, e.g., to perform a calculation, to display specified data on a screen, etc. For example, the server may transmit a request adapted to cause a client computer to perform one or more of the method steps described herein, including one or more of the steps of  FIG. 9 . Certain steps of the methods described herein, including one or more of the steps of  FIG. 9 , may be performed by a server or by another processor in a network-based cloud-computing system. Certain steps of the methods described herein, including one or more of the steps of  FIG. 9 , may be performed by a client computer in a network-based cloud computing system. The steps of the methods described herein, including one or more of the steps of  FIG. 9 , may be performed by a server and/or by a client computer in a network-based cloud computing system, in any combination. 
     Systems, apparatus, and methods described herein may be implemented using a computer program product tangibly embodied in an information carrier, e.g., in a non-transitory machine-readable storage device, for execution by a programmable processor; and the method steps described herein, including one or more of the steps of  FIG. 9 , may be implemented using one or more computer programs that are executable by such a processor. A computer program is a set of computer program instructions that can be used, directly or indirectly, in a computer to perform a certain activity or bring about a certain result. A computer program can be written in any form of programming language, including compiled or interpreted languages, and it can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. 
     A high-level block diagram of an exemplary computer that may be used to implement systems, apparatus and methods described herein is illustrated in  FIG. 10 . Computer  1000  comprises a processor  1010  operatively coupled to a data storage device  1020  and a memory  1030 . Processor  1010  controls the overall operation of computer  1100  by executing computer program instructions that define such operations. The computer program instructions may be stored in data storage device  1020 , or other computer readable medium, and loaded into memory  1030  when execution of the computer program instructions is desired. Thus, the method steps of  FIG. 9  can be defined by the computer program instructions stored in memory  1030  and/or data storage device  1020  and controlled by processor  1010  executing the computer program instructions. For example, the computer program instructions can be implemented as computer executable code programmed by one skilled in the art to perform an algorithm defined by the method steps of  FIG. 9 . Accordingly, by executing the computer program instructions, the processor  1010  executes an algorithm defined by the method steps of  FIG. 9 . Computer  1000  also includes one or more network interfaces  1040  for communicating with other devices via a network. Computer  1000  also includes one or more input/output devices  1050  that enable user interaction with computer  1000  (e.g., display, keyboard, mouse, speakers, buttons, etc.). 
     Processor  1010  may include both general and special purpose microprocessors, and may be the sole processor or one of multiple processors of computer  1000 . Processor  1010  may comprise one or more central processing units (CPUs), for example. Processor  1010 , data storage device  1020 , and/or memory  1030  may include, be supplemented by, or incorporated in, one or more application-specific integrated circuits (ASICs) and/or one or more field programmable gate arrays (FPGAs). 
     Data storage device  1020  and memory  1030  each comprise a tangible non-transitory computer readable storage medium. Data storage device  1020 , and memory  1030 , may each include high-speed random access memory, such as dynamic random access memory (DRAM), static random access memory (SRAM), double data rate synchronous dynamic random access memory (DDR RAM), or other random access solid state memory devices, and may include non-volatile memory, such as one or more magnetic disk storage devices such as internal hard disks and removable disks, magneto-optical disk storage devices, optical disk storage devices, flash memory devices, semiconductor memory devices, such as erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), compact disc read-only memory (CD-ROM), digital versatile disc read-only memory (DVD-ROM) disks, or other non-volatile solid state storage devices. 
     Input/output devices  1050  may include peripherals, such as a printer, scanner, display screen, etc. For example, input/output devices  1150  may include a display device such as a cathode ray tube (CRT), plasma or liquid crystal display (LCD) monitor for displaying information to the user, a keyboard, and a pointing device such as a mouse or a trackball by which the user can provide input to computer  1100 . 
     Any or all of the systems and apparatus discussed herein, including micro-display projector  210  and controller  295  may be implemented using a computer such as computer  1000 . 
     One skilled in the art will recognize that an implementation of an actual computer or computer system may have other structures and may contain other components as well, and that  FIG. 10  is a high level representation of some of the components of such a computer for illustrative purposes. 
     The foregoing Detailed Description is to be understood as being in every respect illustrative and exemplary, but not restrictive, and the scope of the invention disclosed herein is not to be determined from the Detailed Description, but rather from the claims as interpreted according to the full breadth permitted by the patent laws. It is to be understood that the embodiments shown and described herein are only illustrative of the principles of the present invention and that various modifications may be implemented by those skilled in the art without departing from the scope and spirit of the invention. Those skilled in the art could implement various other feature combinations without departing from the scope and spirit of the invention.