Abstract:
The invention concerns a combined surgical microscope system having a surgical microscope and a retinal diagnostic device of modified configuration having transscleral pulsed illumination.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims priority of the German patent application 103 02 401.8 which is incorporated by reference herein. 
     FIELD OF THE INVENTION 
     The invention concerns a surgical microscope having a beam path for a camera. 
     BACKGROUND OF THE INVENTION 
     With known surgical microscopes, for example with the M841 of the Leica company (see brochure, “The Leica M841—The Ultimate Surgical Microscope System for Ophthalmology,” Publication no. 10 M1 841 Oen, printed VII.2000), surgery is performed on and below the retina (fundus) when ophthalmological diseases are present. The region extends from the macula to the ora serrata. 
     There also exist retinal diagnostic devices specifically for this sector, for example the retinal diagnostic device of Medibell Medical Vision Technologies Ltd., Haifa, Israel, referred to (in a brochure without publication information) as the “Panoret 1000—Wide-Angle Digital Retinal Camera.” Retinal diagnostic devices in general are also commonly referred to as “retinal cameras” or “fundus cameras,” and are produced by a number of manufacturers. 
     Retinal cameras are used for the diagnosis of corresponding diseases, and are sufficiently known. 
     The basic principle of such retinal cameras is that the observation beam path is guided through the patient&#39;s pupil together with the illuminating beam path. 
     Guidance of the observation and illumination beam paths together through the patient&#39;s pupil is, however, very difficult to implement. Compromises are therefore accepted. 
     The Medibell company developed the digital retinal camera indicated above, in which the observation beam was separated from the illumination beam so that these difficulties could thereby be circumvented. Observation is performed using a special optical system in direct contact with the patient&#39;s eye. Illumination is conveyed into the patient&#39;s eye in transscleral fashion (i.e. through the sclera of the eye) using a fiber illumination system. 
     The light source comprises three color diodes that are pulsed. The highresolution digital BW (black-and-white) camera is triggered simultaneously with the three colored light pulses. Image processing of the BW image yields an outstanding high-resolution color image on the color monitor or alternatively, given appropriate real-time processor performance, a live image. A similar arrangement, although not with pulsed color diodes but rather with a white-light source with color filter selection, is known from U.S. Pat. No. 6,309,070. 
     For a surgeon, it is desirable to use a retinal diagnostic device during an operation as well, i.e. not only for separate diagnosis. The reason is that utilization of the retinal diagnostic device is extremely cumbersome, since surgery using the surgical microscope must be interrupted in order to move the retinal diagnostic device over the patient&#39;s eye in order to make the desired (interim) diagnosis. The retinal diagnostic device must then, if applicable, be exchanged once again with the surgical microscope. Another desire on the part of ophthalmic surgeons is to receive from the diagnostic device not a separate, monoscopic image of the retina, but rather an enlargeable and, if applicable, stereoscopic one. 
     SUMMARY OF THE INVENTION 
     From these desires and from the disadvantages that presently exist, there arises the object upon which the invention is based, that of creating an improved surgical microscope that, while it is being used, permits the making of a diagnosis as in the case of a retinal diagnostic device, with no need to remove the surgical microscope from the operating position. 
     This object is achieved by a surgical microscope system generally comprising a surgical microscope having an observation beam path, a beam splitter arranged in the observation beam path, and a retinal diagnostic device having a digital retinal camera and a camera beam path from the beam splitter to the digital retinal camera. 
     The retinal diagnostic device preferably includes a retinal lens, a beam transposer, and an auxiliary lens movable into and out of the observation beam path, preferably under the control of a computer. In one embodiment, the computer also controls an illumination source and optical branching switch for selectively supplying light to the microscope or the retinal diagnostic device as needed. 
     Further embodiments of the invention are described herein. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be explained in further detail, symbolically and by way of example, with reference to Figures. The Figures are described in continuous and overlapping fashion. Identical reference characters denote identical components, and reference characters having different indices indicate functionally identical or similar components. In the drawings: 
         FIG. 1  shows the systematic configuration of a surgical microscope system in which, according to the present invention, a surgical microscope is combined with a retinal diagnostic device; 
         FIG. 2  shows a variant embodiment of the invention in which a common light source is provided and it is possible, based on a displacement of the light source and/or of the light guide, to switch the light feed to the respective light guide; and 
         FIG. 3  shows a further variant embodiment of the invention in which a common light source and an optical light branching switch are provided. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     As is evident from  FIG. 1 , the inventive idea encompasses the fact that the retinal diagnostic device comprises a first component  13  and a second component  23 . A surgical microscope  3  is incorporated between first component  13  and second component  23 . In addition, a camera beam path  25  is coupled out of an observation beam path  24  by means of a beam splitter  7 , as is usual, for example and in a manner known per se, for photographic or video documentation. After beam splitter  7 , camera beam path  25  is directed through imaging lenses  12 ,  12   a  (lens groups can also be used instead of individual lenses) and through a deflection element  20  to a digital camera  13 . Deflection element  20  that is depicted represents one possible optical deflection system and can comprise mirrors and/or prisms, and generates a rightreading and upright image on the image sensor of camera  13 . The image sensor of camera  13  is typically an array of light sensitive pixels, for example a CCD array. 
     The imaging lenses or lens groups  12 ,  12   a  can selectably be displaced with respect to one another, so that the reproduction scale is variable and separate focusing is possible. The two lenses or lens groups  12 ,  12   a  form, together with deflection element  20 , an imaging system  30  that alternatively can also comprise more than two lenses or lens groups  12 ,  12   a , which alternatively can also be arranged in either fixed or axially movable fashion in camera beam path  25 . 
     The electronic signals of the camera are conveyed via an image processing system  14  to a computer  17 , and can be viewed as an image on a monitor  18 , outputted in data output  19  as a printed image, or stored on known storage media, and can also be conveyed into a central document management system  27 . 
     A stroboscopic light source  15  having at least two, in particular three color LEDs is triggered via computer  17  and camera  13  in such a way that light is radiated via a light guide  16  onto a patient&#39;s eye  1  only when an image is at that time being acquired with camera  13 . 
     Surgical microscope  3 , together with the retinal diagnostic device, constitutes a system which offers two application modes: an application mode as a surgical microscope, and an application mode as a retinal diagnostic device (fundus mode). 
     When the system is in fundus mode, a retina lens  23  together with a beam transposer  11  and an auxiliary lens  28 , which are connected to surgical microscope  3  by means of a mechanical pivoting-in apparatus  21 , are pivoted in front of a main objective  4 . Beam transposer  11  transposes the left and right beam paths of surgical (stereo)microscope  3  in order to eliminate a pseudo-stereo effect that is caused by front-mounted retina lens  23 . Beam transposer  11  can alternatively also be incorporated into surgical (stereo)microscope  3  at a different point  22 . It is activated by computer  17  when the latter is switched into fundus mode. Auxiliary lens  28 , with main objective  4 , images at infinity the intermediate image  29  of fundus  2  generated by retina lens  23 . 
     When the system is not in fundus mode, i.e. in the surgical (stereo)microscope application mode, retina lens  23 , beam transposer  11 , and auxiliary lens  28  are not pivoted in front of main objective  4 . Patient&#39;s eye  1  is illuminated directly, via a deflection element  10  in surgical (stereo)microscope  3 , by way of a microscope illumination system  8  that comprises a microscope light source  26  and a light-guiding cable  9 . 
     Microscope light source  26  can advantageously be identical to camera light source  15 , so that the patient&#39;s eye is also illuminated with the three-color LED stroboscopic light that minimizes retinal impact. It is preferable in this case if the flicker limit of observer&#39;s eye  6  is exceeded, so that a bright image impression is created but there is no need to direct too much-light energy into patient&#39;s eye  1 . 
     A further inventive idea consists in the fact that optical adaptation of retinal camera  13  onto surgical microscope  3  is accomplished using a special imaging system  30 . As mentioned, it comprises lenses or lens groups  12 ,  12   a  and deflection element  20 . The inventor has recognized that it is sufficient if imaging system  30  is calculated and corrected specifically only for the wavelengths of the at least two color LEDs. A color correction such as that performed, for example, for visual observation in surgical microscope  3  is not necessary in this case. It is limited exclusively to the wavelengths offered by light source  15  and their discrete spectral distribution. According to the present invention, it is advantageously possible to use diffractive elements for chromatic correction here, in order to reduce the weight and overall length of imaging system  30 . 
     In order to ensure optimum illumination of the pixels of the image sensor of camera  13 , the beam profile after imaging system  30  in the light direction is calculated so that shadowing of the pixels by adjacent pixels does not occur, i.e. so that the bundle of rays strikes the surface of the image sensor&#39;s pixels almost perpendicularly. Advantageously, the resolution achieved by correction of the lens system need be no greater than that defined by the camera&#39;s pixel structure. 
     Since retina lens  23  and auxiliary lens  28 , unlike imaging system  30 , are also used visually by the surgeon, their optics are corrected in the conventional manner. Retina lens  23  can comprise a system that is in direct contact with the patient&#39;s eye, as is the case with the retinal camera of the Medibell company (U.S. Pat. No. 6,267,752); or known non-contact optical systems, e.g. of the Oculus company, can also be used. 
       FIG. 2  shows a variant embodiment of a surgical microscope system according to the present invention having a surgical microscope  3  and an integrated retinal diagnostic device, in which a single light source  15  (e.g. a two- or three-color LED stroboscopic light) is provided both to feed light into light guide  9  for conventional illumination for surgical microscope  3 , and to feed light into light guide  16  for transscleral illumination for the retinal diagnostic device. Simultaneous illumination through both light guides  9  and  16  is not provided for the retinal diagnostic device application mode (fundus mode), and is also difficult to implement, since the illumination supplied from light guide  9  for surgical microscope  3  would need to shine through the elements (auxiliary lens  28 , beam transposer  11 , and retina lens  23 ) pivoted in below main objective  4 . Because of these optical elements that are arranged according to the present invention for operation of the retinal camera, simultaneous light feed to light guides  9  and  16  in fundus mode is not preferred. Accordingly, as schematically depicted, light guides  9  and  16  can be slid in front of light source  15 , and/or light source  15  can be slid in front of light guide  9  and/or  16  that is required depending on the application mode selected (fundus mode or surgical microscope mode). This would mean the following arrangements according to the present invention for the two application modes: 
     In findus mode, light is fed only to light guide  16 ; microscope illumination system  8  does not supply any illumination, which would need to penetrate through the pivoted-in elements (auxiliary lens  28 , beam transposer  11 , and retina lens  23 ). 
     In surgical microscope mode, the optical elements comprising auxiliary lens  28 , beam transposer  11 , and retina lens  23  are not pivoted in front of main objective  4 , and patient&#39;s eye  1  can thus be illuminated in conventional fashion through the pupil using microscope illumination system  8 . In other words, light needs to be fed only to light guide  9 . If simultaneous or exclusive transscleral illumination via light guide  16  is advantageous in this application mode, then according to the present invention the two illumination modes are intended to be combinable without restriction. 
       FIG. 3  symbolically depicts the manner in which the requisite illumination can be switched by means of an optical light branching switch  31  controlled by computer  17 . 
     PARTS LIST 
     
         
           1  Patient&#39;s eye 
           2  Retina (fundus) 
           3  Surgical microscope 
           4  Main objective 
           5  Stereo tube 
           6  Observer&#39;s eye 
           7  Beam splitter 
           8  Microscope illumination system 
           9  Light guide 
           10  Deflection element 
           11  Beam transposer 
           12 ,  12   a  Lens or lens group 
           13  Camera 
           14  Image processing system 
           15  Light source 
           16  Light guide 
           17  Computer 
           18  Monitor 
           19  Data output 
           20  Deflection element 
           21  Mechanical pivoting-in apparatus 
           22  Beam transposer (alternative installation location to  11 ) 
           23  Retina lens 
           24  Observation beam path 
           25  Coupled-out camera beam path 
           26  Microscope light source 
           27  Central document management system 
           28  Auxiliary lens 
           29  Intermediate image 
           30  Imaging system 
           31  Optical light branching switch