Abstract:
The present invention relates to a system for the stereoscopic examination of a patient&#39;s eye using a slit-lamp microscope ( 3 ), wherein the patient&#39;s eye ( 1 ) is illuminated by a light strip of a predetermined cross section which is emitted by a light source ( 5 ). The light source ( 5 ) is arranged on the vertical arm ( 20 ) of a support ( 7 ) and the eye ( 1 ) to be examined is placed in an essentially horizontal plane on one side of said support. The stereo-microscope ( 3 ) is essentially placed on a plane which is located on the side opposite to the first side of the support ( 7 ). The vertical arm ( 20 ) of the support ( 7 ) is made in the shape of a column having a narrow cross section so as to minimize the optical obstruction between the stereo-microscope ( 3 ) and the patient&#39;s eye. Using at least one beam ( 30   b ) from the stereo-microscope ( 3 ), a partial ray is stopped down and the image information of said ray is directed to a reception unit ( 44 ) located in said stereo-microscope ( 3 ).

Description:
This application is the national phase under 35 U.S.C. §371 of PCT International Application No. PCT/CH98/00480 which has an International filing date of Nov. 11, 1998, which designated the United States of America. 
    
    
     The invention relates to a slit lamp device and a lens supporting unit as an attachment for the device. 
     BACKGROUND OF THE INVENTION 
     A slit lamp microscope is known, for example from the company Haag Streit under the name “Original slit lamp 900 BM” and is described with its essential features in DE-A 1 133 911. The known slit lamp device had a viewing unit for stereoscopic examination of the eye and an illumination unit for the eye which is to be examined. The cross section of a illumination spot on or in the eye can be adjusted by a diaphragm which is adjustable in width and height. The illumination unit was located on a vertically running branch of a holding unit. The eye to be examined could be positioned in a roughly horizontally running plane on one side of the holding unit. The viewing unit was located roughly in the plane on the side of the holding unit opposite it. The holding unit had three columns. The illumination optics rested on the two outer columns. On the third middle column which was made as a stub column there was a deflection mirror which guided the beam of the illumination unit to the eye. In the intermediate spaces between one outer column at a time and the stub column the beam paths were guided to the viewing unit. 
     In U.S. Pat. No. 5,216,456 a three-column slit lamp device is described, the middle column bearing the deflection mirror for illuminating the eye. All three columns are joined via a connecting plate on which then an illumination unit is placed. 
     In U.S. Pat. No. 4,331,392 the illumination unit is located in the lower part of the slit lamp device and thus necessarily has a construction which is completely different from the invention; in it the illumination unit is located at the top. The arrangement of an illumination unit in the upper part of the slit lamp device compared to the arrangement of U.S. Pat. No. 4,331,392 allows simple replacement of the illumination source. The slit lamp device of U.S. Pat. No. 4,331,392 is foreign to that of the invention and thus not further examined below. 
     In EP-A 0 091 334 a slit lamp device is described with which the eye could be examined and a laser beam was guided for eye treatment. The slit lamp device of EP-A 0 091 334 was built analogously to that of DE-A 1 133 911, an additional column stub being present for guidance of the laser beam. The analogous structure can be seen especially in FIG. 2 which shows a vertical lengthwise section through the device. FIG. 2 shows cutaway the middle column which bears the deflection mirror. Furthermore, the left side column is shown as seen from the visual field of the patient. The connecting plate for the two side columns on which the illumination unit (here labelled  20 ) sits is shown cutaway. 
     SUMMARY OF THE INVENTION 
     The object of the invention is to devise a slit lamp device which allows good patent-physician contact, ensures efficient examination and which can be economically produced in an aesthetically pleasing form with outstanding optical properties. 
     The invention is characterized by as little material as possible between the observing and examining physician and the patient in order to ensure efficient examination and good patient-physician contact. A structure which avoids material between the physician and patient is achieved by means of a vertically running branch of a holding unit for an illumination unit made as one column with a narrow column cross section. The narrow column area is preferably made at eye height. Efficient examination is furthermore supported by a video recording. The compact configuration achieved likewise enables economical manufacture. The features of the invention also increase the examination efficiency since the viewing, observing or examining individual need no longer turn his gaze from the viewing unit to look for the controls. The most important controls can be operated with only one hand. 
     If a Greenough microscope is used as an observation unit preferably in conjunction with the slender holding column as a holding unit, a further reduction in the size of the device results. The video viewing arrangement described below with a Greenough microscope can also be used on other slit lamp devices with the corresponding adaptation. Also the size of the device can be reduced; but its mass does not decrease as much as when using the single-column holding unit. 
     One partial beam which is guided to a recording element of a recording unit is masked out into one of the two beam paths of the Greenough microscope for display and evaluation purposes. If the decoupling of the partial beam as was the case in conventional slit lamp devices, having a different microscope than a Greenough microscope, were to take place, much larger dimensions would result. 
     The structure described below furthermore easily allows integration of optical filters which enable better observation results. 
     In one preferred version, a lens supporting unit can simply be slipped on as an accessory. With this accessory part, studies can be done on the vitreous body and on the ocular fundus. These examinations have been done in the past with a so-called “movable Hruby adapter glass”. This means had a rod on which one examination lens was arranged with a capacity to swivel. The rod had a vertically running guide rod which was guided in the direction of the patient in one slot on the slit lamp device. This guide rod led through an attachment plate which was attached to the chin holder for the patient&#39;s head. Directly underneath the lens there was a small lever as the handle for moving the lens. The examinations performed with the known “adapter glass” were often not reproducible since when the lever was released generally the lens moved. Photographs for documentation were thus hardly possible. 
     Embodiments and other advantages of the invention are described below. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     The following examples of the device and the slit lamp microscope are detailed using the drawings. 
     FIG. 1 shows a side view of the slit lamp device with assignment to the human eye, here the video recording unit  46  which is shown by way of example in FIG. 6 not being used and therefore the housing opening being closed with a plug  50   b,    
     FIG. 2 shows a view of the slit lamp device which is shown in FIG. 1, a view turned 90° around a vertical axis, in the direction of viewing II there, 
     FIG. 3 shows an overhead view proceeding from the patient&#39;s eye to a holding unit of the slit lamp device which is shown in FIGS. 1 and 2, 
     FIG. 4 shows a schematic of known Greenough microscopes, 
     FIG. 5 shows a cross section through the modified Greenough microscope used in the device from FIGS. 1 and 2 as a viewing unit, here in a single figure two different layers of optical components being shown for one different enlargement each, 
     FIG. 6 shows a cross section along the section line VI through one beam path of the Greenough microscope shown in FIG. 5 for representation of an arrangement of a video recording unit, to the recording element of which the one partial beam of this beam path is guided, 
     FIGS. 7 a  to  7   f  show two embodiments of arrangements of optical components and their distances in the two beam paths of the Greenough microscope which is shown in FIGS. 5 and 6, the reference numbers corresponding to those in the Figures, the numerical data are in millimeters. O′ is the object plane without a protective glass  31 , B is the image plane for visual examination and Bv is the image plane of the video recording element  44 ; FIGS. 7 a ,  7   c  and  7   e  shown the location of optical components for one enlargement and FIGS. 7 b ,  7   d  and  7   f  for the others, 
     FIG. 8 shows one version of the viewing unit shown in FIG. 5, 
     FIG. 9 shows a cross section along the section line IX in FIG. 8 for representation of the behavior of the partial beam which is decoupled from one of the observation beams and which is guided onto a video recording element of a video recording unit, 
     FIG. 10 shows a cross section through the video recording unit which is shown in FIG. 9 as a separate component, 
     FIG. 11 shows a cross section through an illumination unit of the slit lamp microscope which is shown in FIG. 1, 
     FIG. 12 shows an overhead view of the illumination unit which is shown in FIG. 11, 
     FIG. 13 shows a side view of the illumination unit with the viewing direction XIII shown in FIGS. 2 and 12, 
     FIG. 14 shows an overhead view of a guide lever of the slit lamp device in the viewing direction which is shown in FIG. 1, the cover on the upper part of the guide lever being removed, 
     FIG. 15 shows the slit lamp device which is shown especially in FIG. 1 with a removable lens supporting unit, 
     FIG. 16 shows the supporting unit which is shown in 
     FIG. 15 as a separate accessory part in a larger representation, 
     FIG. 17 shows the supporting unit which is shown in FIG. 16 in the viewing direction XVII there, and 
     FIG. 18 shows the supporting unit which is shown in FIG. 17 in the viewing direction XVIII there. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The slit lamp device which is shown in FIGS. 1 and 2 as a device for stereoscopic examination of an eye  1  has a viewing unit  3  and an illumination unit  5 . The viewing unit  3  is held with a holding unit  23  and the illumination unit  5  is held with a holding unit  7 . As is detailed below, the illumination unit  5  can be used to produce a light beam  9  as radiation which can be guided via a deflection mirror  10  which is located on the holding unit  7  into or onto the eye  1 . The cross section of the light beam  9  can be adjusted according to the details below, especially as a thin streak of light. The holding unit  7  is located on a foot  11  of the device to be able to swivel via a swivel unit with a vertical swivel axis. 
     The holding unit  7  is made as a L-shaped component which is located with a swivelling capacity on the foot  11  of the device on the end of a horizontally running leg  13  in a swivel joint  15  which can be swivelled around a vertical axis  14 . The location of the axis  14  is chosen such that it runs past the front of the eye for a human forehead which is placed against a (only suggested in the drawings) forehead band  17  of a head holder (not shown). The other leg  20  of the L-shaped holding part  7  runs vertically and, as stated above, is made as a single column. So that between the viewing unit  3  and the eye  1  of the patient there is only slight optical distortion, a single column is used as shown in FIG.  3 . In the area of the eye height of the patient the horizontal cross section of the holding unit  5  is greatly reduced. There is a deflection mirror  10  on this area  18  which reduces the cross section. The cross section is made as narrow as possible. The reduction of the horizontal cross section is limited by mechanical stability constraints and the width of the deflection mirror  10  which is necessary for illumination beam guidance. Furthermore guidance of the elements described below within the leg  20  which is made hollow inside militates against any reduction in the width of the area  18 . 
     In its cavity a rod-shaped adjustment mechanism (not shown) runs for adjustment of the slit width in the illumination unit  5  which is located on the top end of the leg ( 20 ). The rod-shaped adjustment mechanism (not shown) acts with a cam which is not shown and which lies within the holding unit  7  in its external area of the union between the two legs  13  and  20 . On each of the two ends of the cam there is a adjustment knob  21   a  and  21   b . The surface of each adjustment knob  21   a  and  21   b  can be easily gripped. 
     The viewing unit  3  is likewise located on an L-shaped holding unit  23  analogously to the illumination unit  5 . This holding unit  23  also has one horizontally and one vertically running leg  24  and  25 . The end of the horizontal leg  24  is swivel mounted around the vertical axis  14  analogously to the holding unit  7  and with the swivel joint  15  which is elongated downward is swivel-mounted on the foot  11  of the device independently relative to the holding unit  7 . On the outside of the leg  25  a breathing protection shield  27  is interchangeably held. On the top end of the leg  25  the viewing unit  3  is located at a height which makes it possible to look into the eye  1 . 
     The viewing unit  3  is fundamentally made as a Greenough microscope. The fundamental structure of this stereomicroscope is shown in FIG. 4 as a sample figure from Karl Muetze, “ABC of Optics”, key word “Stereomicroscopy”, 1961, Verlag Werner Dausin, Hanau/Main. According to this reference a Greenough microscope is used for direct three-dimensional viewing. It has two separate microscopes which are tilted by an angle of 14 to 16° against one another, this angle corresponding roughly to the angle of convergence of the human eye axes when viewing an article from the distance of the conventional field of vision of 25 cm. A set of Porro prisms P of the first or second type aligns the image so that it is seen in the same location as the object. This is necessary to obtain an orthoscopic (with correct depth) image. 
     In a Greenough microscope the objectives are very close to one another, by which according to the statements in the aforementioned citation high apertures are not possible. The device as claimed in the invention is different from a typical Greenough microscope, as is shown by the cross section in FIG.  5 . FIG. 5 shows the two individual microscopes  29   a  and  29   b  which are separated from one another in a cross section tilted towards one another at an angle of 13°. The beam paths of the individual microscopes  29   a  and  29   b  are labelled  30   a  and  30   b . In the top part of the figure the location of the optical components is shown for one enlargement scale and in the lower half of the figure for another. The enlargement scales are switched with the switch lever  59  which can be seen in FIG.  2 . 
     At the observation beam inlet into the Greenough microscope  3  there is a single protective glass  31  for the two beam paths  30   a  and  30   b  in front of the two objectives  33   a  for the one enlargement scale and in front of the two objectives  33   b  for the other enlargement scale. In the “upper” beam path  30   a  a plane-parallel plate  35  for optical matching to the splitter prism  37  which is downstream of the objective  33   a  in the “lower” beam path  30   b  follows the objective  33   a . The “upper” and the “lower” beam path are the left and right beam path as shown in FIG.  2 . The plane-parallel plate  35  is followed by a Porro prism  36  which is upstream of an eyepiece  39 , especially an interchangeable eyepiece. Both components are shown only in the “lower” beam path. 
     In the beam path  30   b  there is image decoupling for a video recording unit  46 . This is done with a splitter prism  37  which divides the beam path  30   b  into one component beam  42   a  via the Porro prism  40  to the eyepiece  39  and into another component beam  42   b  via a deflection prism  41  and a video objective  43  to a recording element  44  of the video recording unit  46 . The video recording unit  46  consists of a splitter prism  37 , the deflection prism  41 , the video objective  43  and the video recording element  44 . The video recording element  44  is held in a mount  48   a  which plugs in an adjustment sleeve  48   b . The mount  48   a  is held with a clamp screw  48   c  in the adjustment sleeve  48   b . The adjustment sleeve  48   b  sits in a housing hole  50   a  with the capacity to turn and to be displaced and can be fixed with clamp screws  48   d  which fit in a peripheral groove on the outside jacket of the calibration sleeve  48   b . The optical image can be adjusted by moving the mount  48   a  and the calibration sleeve  48   b . So that no dirt can penetrate through the housing hole  60   a , this is closed by a removable plug  50   b . The video recording unit  48  can be interchanged as a whole. Likewise the video recording element is interchangeable. 
     In addition to visual examination, video photographs can thus also be taken for direct observation or for recording (documentation). The arrangement of the recording unit  44  is shown in FIG.  6 . 
     FIGS. 7 a  and  7   f  show two optical versions for different enlargement scales. FIGS. 7 a ,  7   c  and  7   e  show a version with one objective  33   a  and  33   b  each with 1.6× enlargement and in the video beam path with one objective  43  with likewise 1.6× enlargement. 
     In the other version which is shown in FIGS. 7 b ,  7   d  and  7   f , the components which are different from those in FIGS. 7 a ,  7   c  and  7   e  are labelled with an apostrophe &#39;. In this version one objective  33   a′  and  33   b′  each with 1:1 imaging and in the video beam path with one objective  43 ′ with the same enlargement are used. Other versions are of course possible. 
     The illumination unit  5  has two levers  45   a  and  45   b  which can be swivelled around a horizontal axis and which are arranged on top of one another. With these levers  45   a  and  45   b  the height and the width of a diaphragm opening can be adjusted. The cross section of this diaphragm opening defines the cross section of the thin streak  9  of light which is to be aimed at the eye  1 . With these two levers, additionally a blue or gray filter can be swivelled into the illumination beam path  9  and out again. The swivelling in and out takes place in the end region of the swivelling process of the pertinent lever  45   a  and  45   b.    
     Likewise a yellow filter  58  can be placed in the beam paths  30   a ,  30   a′ ,  30   b , and  30   b′  with an adjustment device on the viewing unit  3 . The yellow filter  58  here consists of two partial vapor depositions on the inside of the protective glass  31 . With the adjustment device  47  the protective glass  31  can be turned so that the two partial vapor depositions  58  lie on the one hand in front of the objective  33   a  and  33   b  (in the beam paths  30   a  and  30   b  as is suggested in FIGS. 3 and 5) and on the other next to them (not in the beam path  30   a  and  30   b ). 
     If fluorescein is applied to the surface of the eye for example when a contact lens (not shown) is inserted, and is illuminated with blue light (blue filter folded down), yellow fluorescence occurs which can be easily observed with a Greenough microscope  3  when there is a yellow filter in the observation beam path (check of fit of contact lenses). 
     On the viewing unit  3  there is a switching lever  59 . With this switching lever  59 , depending on the desired enlargement, the objectives  33   a  and  33   b  and  33   a′  and  33   b′ , as are shown in FIGS. 7 a ,  7   c , and  7   c , can be alternately swivelled in the beam paths and then in the other lever position those of FIGS. 7 b ,  7   d  and  7   f  can be swivelled. FIGS. 7 e  and  7   f  shown the beam behavior in a position swivelled relative to FIGS. 7 a  to  7   d  by 90°. On the foot  11  of the device there is furthermore a power connection  61  for the light source in the illumination unit  5  and for the recording unit  44 . 
     To observe the entire visual field, underneath the deflection mirror  10  which is arranged at 45° there is a cold light guide which is not shown. Furthermore a tonometer for measuring the eye pressure can be placed in an adapter  63  on the housing of the Greenough microscope. The brightness of the “slit lamp” in the illumination unit  5  is adjusted by a manual controller  49  which is located on the foot  11  of the device. The electrical cable for brightness control or power supply runs within the hollow holding unit  7 . The positioning of the device horizontally in the X direction and the Y direction is done using a guide lever  51  which is located on the foot  51  of the device, often also called a “joystick”. By lateral deflection  53  the foot  11  of the device can be moved laterally on an axis  52  in the Y direction  54 . Movement in the X-direction  56  is also possible by swivelling  55  of the guide lever  56  forward and backward. The movement in the X-direction takes place via rotary motion of the wheels  57   a  and  57   b  which are located on either side on the axis  52  and which roll off on rails which are not shown and which are attached to a base which is not shown. On this base there is also a head holder which is not shown and which has a forehead band  17 . 
     The guide lever  51  can furthermore be turned around its vertical axis. In order to achieve a good turning capacity, the coupling lever  51  is provided in its top jacket area with peripheral ribbing. The turning causes synchronous vertical adjustment of the holding units  7  and  23  and thus a vertical adjustment of the thin streak  9  of light which is to be directed into the eye  1  together with the viewing unit  5 . 
     Since the leg  20  of the holding unit  7  can be made very slender, for reasons of manufacture the laying the power cable in it can be abandoned. The power supply in this case passes to the power connection  61 , from the latter to the manual controller  49  and from it back again to the power connection  61  and from it then via an external (cable which is not shown) via the (head support which likewise is not shown) into the illumination unit  5 . 
     Instead of decoupling for the recording unit  44 , as described above, with partially transparent components for example via the splitter prism  37 , only a fraction of the beam cross section can also be decoupled using a decoupling mirror or a decoupling prism, as is shown for example in FIGS. 8 to  10 . FIG. 8 shows one version  65  of the viewing unit  3  (Greenough microscope) which is shown in FIG.  5 . The input objectives  67   a  and  67   b  of the individual microscopes  69   a  and  69   b  and their location are made analogously to the objectives  33  and  33   b′  in FIG.  5 . Since decoupling of a component beam  71   a  takes place to a video recording element  70  which is made analogously to the video recording element  44  (visible in FIGS. 9 and 10) by decoupling a fraction of the incident beam  73   a  (analogously to beam  30   b ), optical compensation by a plane-parallel plate analogous to plate  35  is not necessary. In this way the structure of the viewing unit  65  is greatly simplified compared to the viewing unit  3 . 
     To decouple a component beam  71   a  a prism  75  is used which partially projects into the cross section of the beam  73   a . The decoupled component beam  71   a  is deflected one more time with a second prism  76  and is imaged with imaging optics (video objective)  77  on the receiving plane of the video recording element  70 . The video recording unit  79  here consists of a prism  75  which geometrically decouples a component beam, a prism  76 , imaging optics  77  and the video recording element  70 . 
     The video recording unit  79  (camera) which is shown in FIGS. 9 and 10 can likewise be replaced as a whole, but also only the video recording element  70  alone can be replaced. The prisms  75  and  76 , the imaging optics  77  and the video recording element  70  are located and held in a housing  81  which with optically fitting can be pushed into the housing opening  82  of the viewing unit  65  such that the prism  75  comes to rest correctly in the beam  73 a for decoupling of the component beam  71   a.  Also here are there shifting and turning of the video recording element  70  to adjust the image. The housing  81  (FIG. 9) analogously to FIG. 6 likewise has a mount for the video recording element  70  and an adjustment sleeve. Fixing takes place here as well with the clamp screws  83   a  and  83   b . By means of the interchangeability of the video recording unit  79  the viewing unit  65  with this video recording unit  79  can be easily refitted among others in terms of salesmanship. Furthermore, after removing the video recording unit  79  the image contrast in both observation beam paths  73   a  and  73   b  is the same. The viewing unit  65  can be produced more easily and thus also more cost favorably compared to the viewing unit  3 . 
     The arrangement of a light source  86  which is inserted into the illumination unit  5  is shown in FIG. 11 in an enlarged cross section. As the light source  86  a so-called high temperature quartz lamp can be used which is held interchangeably in a fitted base  87 . The base  87  sits with a clearance fit in a sleeve  89 . The base  87  has contact pins  90  which fit into matching sleeves of a plug piece  91  which can be removed from the base  87 . From the plug piece  91  a cable  93  passes to an electrical connection piece  94 . The base  87  is kept from sliding out with an elastic clip  95  of spring wire which lies in a groove  97  of the base  87 . The clip  95  is wound roughly in a circular cylinder on its one side, with for example five turns here, forming a “tube piece”  99 . The “tube piece”  99  slips onto a pin  100  with a top end which bears a clamp disk (Seeger circlip ring  101 ) which prevents the “tube piece”  99  and thus the clip  95  from sliding out. 
     The other end of the clip has a pull loop  103  which can be inserted into a peripheral groove  105  in the top of a pin  106 . The clip  95  is elastically pre-bent such that it presses the base  87  into the sleeve  89  and itself presses against the groove  105 . To replace the light source  86  the plug piece  91  must be withdrawn and then the pull loop  103  must be raised only over the upper end of the pin  106 . The light source  86  can now be withdrawn with the base  87 . So that the base  87  can be easily grasped, it projects somewhat over the outer edge of the sleeve  89 . 
     The advantage of the arrangement for holding the light source is its simple configuration. Furthermore, a tool is not required for changing the light source. 
     In the top part  109  of the guide lever  51 , as indicated in FIG. 14, there are switching elements  110   b  and  110   b  for control of the functions of the device or of the functions which control peripheral units which are connected with the viewing device. In the embodiment shown here in the upper part  109  as the switching elements there are two microswitches  110   a  and  110   b  (toggle switches, . . . ) next to one another as signal-delivering elements. The two microswitches  110   a  and  110   b  can preferably be operated from the top  111  of the top part  109  preferably with the thumbs. If the device is to be used in a rough environment, the top  111  is covered to be splashproof by an elastic film. 
     Instead of microswitches, pushbuttons or momentary-contact tumbler switches can also be used. If for example the top part of the switch  110   a  which is made as a momentary-contact tumbler switch is pressed, for example via a motor drive which is not shown, the light slit width of the light source can be reduced. If then the lower part of the switch  110   a  is pressed, the slit would be enlarged. This function would eliminate manual operation of the adjustment knobs  21   a/b  by another hand. Via the switch  110   b  brightness could be controlled in a similar manner; this would result in elimination of adjustment via the manual controller  49 . The treating physician can then continually view without having to glance at these adjustment elements. Also here the physician has the hand required previously for adjustment free for treatment manipulations. 
     With these two switches/momentary-contact tumbler switches  110   a/b  other units can be adjusted. Electrical and signal-engineering connection could take place via the terminal  61  or via a separate terminal which is not shown. For example a tonometer could be moved against the surface of the eye. 
     By actuating the two switches/momentary-contact tumbler switches  110   a/b  adjustments can be made using motorized drives. So that at this point the physician knows in which position the pertinent unit or the slit width or the brightness is found, reflecting the data into the beam path of the viewing unit  3  or  65  can be done. The reflection-in would take place now analogously to beam reflection out for the video recording element  44  or  70 . Instead of the video recording element  44  or  70  there would be only one display element with video information which is being reflected in. Then the prism  37  and  75  can be turned 180° relative to the representations in FIGS. 5 and 8 for reflection-in. 
     If the slit lamp device is also to be used for preferred examination of the vitreous body and the ocular fundus of the patient, the device with a lens supporting unit  203  which can attached and removed again without using tools manually via a coupling  201  is placed with an examination lens  204  in front of the inlet of the observation beam in the viewing unit  3  in the observation beam path, therefore in front of the protective glass  30 . The examination lens  204  is held self-locking with a turning capacity and self-locking in all three-dimensional directions with an adjustment capacity with the lens supporting unit  203 . The lens supporting unit  203 , in contrast to the known Hruby adapter glass which can be used together with a slit lamp, has no mechanical connection to the head holder and chin holder of the patient. 
     The lens supporting unit  203  has a plate-shaped support part  205  from which a cylindrical stud  207  projects. The cross section of the stud  207  is chosen such that it can be inserted with a clearance fit into an axial hole  209  which is shown in FIG.  1 . The axial hole  209  is formed centrally to the vertical axis of the swivel joint  15 . With the swivel joint  15  the holding part  7  for the illumination unit  5  and the holder  23  for the viewing unit  3  can be swivelled. The pin  207  and the axial hole  209  for a plug coupling  201 . Locking of the lens supporting unit  203  is achieved by the plate edge of the support part  206  being provided with a notch  210 . In the inserted state the projecting part of a sheet strip  211  which is located on the front of the horizontal leg  13  of the holding unit  7  fits into this notch  210 . The support part  205  in an extension upward has a roughly cuboidal base part  213 ; on its horizontal top a first carriage  214  is positioned to be movable in the lengthwise direction of the cuboid (in the installed state in the direction towards the patient&#39;s eye  1  and away from it). The carriage  214  is guided on the base part  213  for example in a dovetail guide which can be fixed with a clamp screw  215  which is provided with knurling for better grip. When the clamp screw  215  is loosened, movement by hand is possible. With this guide coarse adjustment of the distance of the lens  204  from the patient&#39;s eye  1  can be done. On the first carriage  214  there sits a second carriage  217  which can be moved in the same direction as the first carriage  214 . The movement takes place however via a likewise knurled fine adjustment screw  219 . Horizontally, perpendicularly to the first and the second carriage  214  and  217  there is a third carriage  220  which can be moved likewise via a fine adjustment screw  221  by turning it. With the two fine adjustment screws  219  and  221  fine adjustment of the examination lens  204  in the horizontal plane takes place. 
     For vertical height adjustment there is a two-part lens post  223  which on its top end bears the examination lens  204 . The lower part  225  sits on the third carriage  220  and tapers prismatically upward. From the top end of the part  225  a blind hole  226  runs centrally into the part  225  in the axis of symmetry. In this blind hole  226  a mandrel  227  sticks which passes into the upper component piece  229  of the lens post  223 . Proceeding from the mandrel projection, the component piece  229  widens prismatically upward. The mandrel  227  can be moved in the blind hole  226 . The vertical height of the examination lens  204  is set manually by this motion. This height adjustment is self-locking based on a frictional force-fit. The self-locking is achieved by a permanent magnet which is captively located in the lower part  225  and which however can move in the direction to the surface of the mandrel  227 . Since the mandrel  227  consists of ferromagnetic material, the permanent magnet in the mandrel  227  which has been inserted into the blind hole  226  is pulled against its surface and thus locks the vertical displacement by self-locking. But locking is only so strong that movement as a result of the inherent weight of the examination lens  204  plus its top component piece  229  is suppressed. But adjustment is possible manually. The location of the permanent magnet is apparent in FIGS. 16 to  18  by a disk-shaped mounting aid  231 . 
     The examination lens  204  lies in a V-shaped recess  232  on the top end of the component piece  229  on its mount jacket  233 . The examination lens  204  is held with a band-like flexible lens holding element  235  which has a chain-like structure. One end of the element  235  is held with a spring  236  roughly in the center on the end of the lateral lengthwise groove  237  of the component piece  229 . The element  235  as a chain-like structure has nubs  239  which are equally spaced in the lengthwise direction and which are separated by intermediate spaces  240  with a thinner band cross-section. One of these intermediate spaces  240  is hooked between two projections  241   a  and  241   b  in a lateral lengthwise groove  243  on the side opposite the lateral lengthwise groove  237 . The spring  236  tensions the lens holding element  235  and thus pulls the examination lens  204  into the recess  232  and fixes it. The lens holding element  235  can have a different structure, for example it can be made as a chain, compared to the nubs  239  and the narrow intermediate spaces  240 . When using a chain likewise the two projections  241   a  and  241   b  could be present; then the chain would be suspended on its outer regions; but also there could be only a single projection into which one chain link at a time is suspended. 
     As detailed above, the lens supporting unit  203  is locked with the notch  210  and a sheet strip  211  which fits it on the holding unit  7 . But equally well there could be other catch elements such as a pin which is arranged radially to the stud  207  and which fits into a corresponding hole in the holding unit  7 . The locations of the pin and hole can of course be interchanged. Also textured surfaces can be used with structures which fit into one another. 
     In order to eliminate disruptive reflections in the examination and to deflect the path of the observation beam, the top part  229  of the lens post can be equipped with a tilting means for the examination lens  204 . The tilting means can be a simple swivel axis. But preferably however three swivel joints spaced apart from one another can be used with swivel axes which run parallel to one another, i.e., there is a angle leg with an adjustable apex angle, and the other leg ends can in turn be swivelled with a swivel joint. On the topmost leg end the examination lens  204  is held with a swivelling capacity. With this arrangement tilting of the lens is possible with preservation of the center of the lens at a stipulated point in space. 
     By using the lens supporting unit  203  the physician can adjust the examination lens  204  optimally to the patient&#39;s eye  1  via its precision three-dimensional adjustment. After adjustment he has both hands free for the examination and treatment to be performed. He can also, especially using the video recording unit  46  and  70 , undertake the corresponding documentation. Instead of the video recording unit a camera can also be flanged in order to undertake the corresponding documentation. Since the examination lens remains adjusted in its position by self-locking, at total rest the recording can be done with the choice of the image extract and sharpness adjustments. 
     Only the embodiment of the invention having the vertically running branch  20  of the holding unit  7  in a single column with the narrow column cross section allows optimum examination of the vitreous body and the ocular fundus using the examination lens  204  which is supported by the lens supporting unit  203 . The lens supporting unit  203  can be used with the initially described, already known slit lamp device which has a three-column holding unit. Also, use together with other slit lamp devices is possible if a corresponding coupling is present.