Observation device and method for observing an eye

Abstract

The present invention relates to an observation device (10) and a method for observing an eye using such an observation device, the observation device having a positioning unit (11) for positioning an optical unit (12) in a beam path (13) of a microscope between the objective lens of the microscope and the eye to be observed, the positioning unit comprising a connecting device (14), a positioning device (15), a receiving device (16) and an optical unit, the optical unit comprising a lens for observing the fundus of the eye and another optical element, the positioning unit comprising a pivoting mechanism (19) by which the optical unit can pivot away from or into the beam path, the positioning unit being coupled to the microscope by means of the connecting device, the lens being adapted to the positioning device by means of the receiving device, the receiving device being at least primarily, preferably entirely, made of plastic material, wherein the positioning device (15) has a lens barrel (24) pivotally mounted on the pivoting mechanism, the lens barrel being at least primarily or entirely made of metal.

Description

Observation device and method for observing eyes The present invention relates to an observation device having a positioning unit for positioning an optical unit in the beam path of a microscope between an objective lens of the microscope and in front of an eye to be observed. The positioning unit comprises a connecting device, a positioning device, a receiving device, and the optical unit, the optical unit comprising a lens and another optical element for observing the fundus of the eye. The positioning unit comprises a pivot mechanism by which the optical unit can be pivoted out of or into the beam path. The positioning unit can be coupled to the microscope by means of the connecting device, and the lens is mounted on the positioning device by means of the receiving device. The present invention also relates to a method for observing an eye using an observation device of this type, the receiving device being made at least predominantly, preferably completely, of a plastic material, and a method for observing an eye using an observation device of this type. Microscopes used for ophthalmic surgery are typically designed for procedures in the anterior region of the eye. If this type of intervention is also to be performed in the posterior region of the eye, it is necessary to add an observation device to the microscope that enables precise focusing of this region of the eye. This type of observation device includes at least one wide-angle lens for wide-angle viewing of the respective posterior portion of the eye and / or an ophthalmoscopic lens. The ophthalmoscopic lens provides an intermediate image in the beam path before the microscope's objective lens, which can be focused by the microscope. To focus this intermediate image, the length of the microscope's beam path needs to be shortened, which can be accomplished with the help of corresponding setting mechanisms on the microscope. However, since it is necessary to switch between different views with and without the ophthalmoscopic lens during ophthalmic surgery, such microscope settings present a hurdle. Therefore, a so-called reduction lens is placed in the beam path before the objective lens. This reduction lens shortens the microscope's beam path and is used in conjunction with the ophthalmoscopic lens. Both lenses are held as an optical unit by a positioning unit of the observation device, which is directly attached to the microscope and can be positioned in the beam path as needed without requiring substantial adjustments to the microscope during surgery. The positioning unit usually comprises a connection device by means of which the positioning unit can be coupled to the microscope. Furthermore, the positioning unit is designed in such a way that the individual lenses can be easily swung into the beam path or inserted into the beam path and removed from it again. An observation device of this type is known, for example, from DE 10 2011 002 940 A1. In order to be able to adjust the intermediate image of the ophthalmoscope lens as precisely as possible to the focal length of the microscope objective, the ophthalmoscope lens is designed to be adjustable along the beam path of the microscope by means of a screw drive. This observation device is designed so that the ophthalmoscope lens can be moved relative to the eye along the beam path. It is advantageous to place the ophthalmoscope lens as close to the eye as possible, since a relatively large area of ​​the eye can then be clearly seen. At the same time, however, contact between the ophthalmoscope lens and the eye must be avoided. Therefore, in order to obtain a clear image of the largest possible area of ​​the eye, it is necessary to constantly adjust the distance of the microscope relative to the eye and coordinate this with the distance of the ophthalmoscope lens relative to the eye. If a certain procedural step during eye surgery (e.g., to aspirate the eye's humor) requires a different distance from the ophthalmoscope lens to the eye, this adjustment of the respective relative distances from the ophthalmoscope lens to the microscope and eye, as well as the subsequent focusing of the acquired image, must be repeated. Currently, it is considered advantageous to make the viewing device and / or the positioning unit from plastic and use them as disposable products, thereby eliminating the need for sterilization of the viewing device and / or the positioning unit. Therefore, viewing devices made from plastic and capable of single use are known. DE 10 2018 127 469 B4 discloses such a viewing device. However, a disadvantage in this case is that, unlike metal, plastic cannot always be used with the required precision for positioning the ophthalmoscope lens, particularly when the positioning device or positioning unit is made of fragile plastic rods. Consequently, when the ophthalmoscope lens is swung into or out of the beam path, it can easily become displaced along or transversely to the beam path. This often necessitates a correction of the ophthalmoscope lens' position, which impedes the effectiveness of the eye surgery. It is therefore an object of the present invention to propose a viewing device and a method for viewing the eye, thereby enabling improved treatment during eye surgery. This object is achieved by an observation device having the characteristics of technical solution 1, a microscope having the characteristics of technical solution 16, and a method having the characteristics of technical solution 17. In the observation device according to the present invention, the observation device has a positioning unit, which is used to position an optical unit in a beam path of a microscope between an objective lens of the microscope and in front of an eye to be observed. The positioning unit includes a connecting device, a positioning device, a accommodating device and the optical unit, and the optical unit includes a lens and another optical element for observing a fundus of the eye. The positioning unit includes a pivot mechanism, and the optical unit can be pivoted away from or into the beam path by means of the pivot mechanism. The positioning unit can be coupled to the microscope by means of the connecting device, and the lens is adapted to the positioning unit by means of the accommodating device. The accommodating device is at least mainly, preferably completely, made of plastic material, wherein the positioning device has a lens barrel pivotally arranged on the pivot mechanism, and the lens barrel is at least mainly or completely made of metal. The observation device according to the present invention can be adapted to a microscope and / or removably connected to the microscope by means of a connecting device. In this case, a lens, which can be an ophthalmoscope lens, is held in the beam path of the objective lens by means of a positioning unit between the eye to be observed and the objective lens. In this case, the lens is intended to be positioned so that the principal axis and / or optical axis of the microscope objective lens extends through the center point of the lens. By means of a pivot mechanism, an optical unit comprising the lens and another optical element (preferably a lens with positive refractive power) can be swung into the beam path and out again as required during eye surgery. In this case, the design of the pivot mechanism is initially irrelevant; what is important is that the optical unit can be completely removed from the beam path and moved into it. Therefore, the pivot mechanism can also be considered a displacement mechanism, by means of which the optical unit can be displaced parallel to the beam path. Furthermore, it is advantageous that the container for housing the lens is essentially made of plastic material, and the lens barrel is essentially made of metal. Therefore, the pivotable lens barrel can be designed in a particularly stable and precise manner, and allows the lens and another optical element to be precisely positioned in the beam path without the need for corrective adjustments, as is the case with purely disposable products. At the same time, due to the fact that the container is made of plastic, it is possible to produce a container with a lens at a particularly low cost. Production can be easily and in large quantities, for example, in the context of an injection molding process. This in turn makes it possible to use the container as a disposable product. In this case, the container can be discarded after the eye surgery has been performed. Sterilizing the container is not necessary. In order to perform subsequent eye surgery, a new container that can be sterilely packaged can be used. The container can be easily adapted to the lens barrel and / or detachably connected to the lens barrel. Another optical element can be positioned below the pivot mechanism. Because the positioning device includes a lens barrel pivotally mounted on the pivot mechanism, placement of the other optical element within the lens barrel is possible. Consequently, movable placement of the other optical element within the lens barrel can be particularly easy. In this case, the other optical element can be easily protected from external influences. The other optical element can be moved relative to the microscope in the longitudinal direction of the beam path by means of a positioning device. In this case, the movable arrangement of the other optical element below the pivot mechanism makes it possible to use the other optical element to adjust the microscope's beam path and / or shorten it to a point where the intermediate image of the lens can be focused. If the other optical element can be moved along the beam path below the pivot mechanism, significantly more space is available for moving it along the beam path compared to when it is positioned above the pivot mechanism. In this case, the distance between the pivot mechanism and the microscope objective is relatively short, as this is the only way to ensure that the optical unit and / or positioning device are completely removed from the beam path. The relatively large adjustment range of the other optical element makes it possible to universally adjust the observation device to different microscope types and, therefore, use them for all of them. In this case, it is no longer necessary to design the other optical element specifically for different microscopes with different beam paths. Alternatively, the lens can remain fixed in one position in the beam path and does not need to be moved relative to the microscope along the beam path. It is only necessary to align the microscope and the lens with the eye. In this case, the beam path can be adjusted simply by moving the other optical element. The lens and the other optical element can each be composed of a plurality of optical components that are connected to each other and, in each case, together form an optical element. The lens can be an ophthalmoscope lens, and the other optical element can be at least one lens with positive refractive power and used to adjust the light beam path. The lens in the lens barrel is movably arranged below the pivot mechanism in the longitudinal direction of the light beam path. The lens with positive refractive power can be a so-called reduction lens, which can be used to shorten the light beam path of the microscope. Because the lens with positive refractive power can be moved along the light beam path in the lens barrel below the pivot mechanism, the light beam path can be easily adjusted over a relatively large adjustment range. The lens with positive refractive power can be simply displaced along the light beam path by means of a screw drive, a helix formed inside the lens barrel, or the like. In this case, the lens barrel can be at least partially rotated. In this case, the lens with positive refractive power can be accommodated in a mount that can be displaced together with the lens inside the lens barrel. The viewing device can include a cover unit made of plastic material to cover the pivotable lens barrel of the positioning device for aseptic covering. The cover unit can be realized in a relatively thin-walled manner so that the cover unit can be in close contact with the pivotable lens barrel. The plastic material can be a rigid or flexible plastic material. In addition, the plastic material can be opaque or the optical part is transparent. In particular, the cover unit can be configured so that the outer surface of the pivotable lens barrel is completely shielded from the environment by the cover unit. In this case, the surgeon can manually grasp and actuate the pivotable lens barrel without sterilizing the lens barrel. In this case, it is only necessary to remove the cover unit that can be manufactured at low cost by plastic material and replace the cover unit with a new aseptic cover unit that has not been used so far. The cover unit can have an upper sterile cover for at least partially covering the end surface of the lens barrel and a lower sterile cover for at least partially covering the circumferential surface of the lens barrel. Therefore, the cover unit can be realized in two parts. When the lens barrel pivots away from the beam path, the upper sterile cover can be placed on the end surface of the lens barrel from above. The lower sterile cover can be placed on the lens barrel from below. In this case, all sides of the lens barrel are surrounded by the cover unit. In particular, when the surgeon manually grasps the lens barrel in the position of pivoting away from the beam path, the upper sterile cover allows the end surface of the lens barrel to be protected from being touched by the surgeon. If the upper sterile cover is used, then if a gap is realized between the lens barrel and the connecting device, then it is also advantageous that when the lens barrel swings into the beam path, the upper sterile cover can be located in this gap. The cover unit can be implemented with at least one connecting element that needs to be destroyed when the cover unit is separated from the positioning device. The connecting element can be implemented by engaging a projection implemented on the lens barrel or engaging a latch element in a groove implemented on the lens barrel. It can also provide a plurality of connecting elements. The connecting element can be implemented or installed flexibly so that the connecting element can easily contact the lens barrel. It is necessary for the connecting element to be constructed in a way that the connecting element and / or the cover unit are destroyed when the cover unit is removed from the positioning device and / or the lens barrel. This prevents the cover unit from being mistakenly reused. The cover unit may have at least one tear strip by means of which the cover unit is at least partially broken. The tear strip may be designed to have a tab that can be easily grasped manually. The tear strip may be implemented by a single weak line or two parallel weak lines in the cover unit. If the cover unit is fixed to the positioning device and / or the lens barrel, for example, by means of a latch connection, the latch connection can be broken by manually actuating the tear strip. This makes it possible to easily remove the cover unit from the positioning device and / or the lens barrel. The receiving device may be implemented with at least one connecting element that needs to be broken when separating the receiving device from the positioning device. This also prevents the receiving device from being mistakenly reused after being separated from the positioning device. The connecting element can, for example, be implemented in such a way that it breaks when the receiving device is removed from the positioning device. The receiving device can be implemented with another, preferably conical, lens barrel. The other lens barrel can be directly attached to the lens barrel and fixedly connected to the lens barrel. The fixed connection can be achieved, for example, by a latch connection. It is particularly advantageous if the other lens barrel is implemented in the form of a cone. In this case, the lens barrel can be adjusted to the shape of the beam path in such a way that the diameter of the other lens barrel is relatively small at the lower end of the other lens barrel. In this case, the lens can be placed on the lower end. It is also advantageous if the other lens barrel is closed. In this case, the other lens barrel can be implemented in the form of a conical sleeve. Another lens barrel can be composed of an upper section and a lower section, wherein the lower section is loosely or spring-loaded mounted on the upper section so that the lower section can be inserted into the upper section. The spring-loaded mounting can be achieved by means of a compression spring that is inserted into the upper section and resists the spring force that allows the lower section to be moved into the upper section. This can prevent undesirable eye injury in the event of a potential collision between the lens and / or the lower section and the eye of the person undergoing surgery. At least one manually actuatable protrusion can be implemented on the lower section, wherein the protrusion can be inserted through and moved along a longitudinal slot implemented in the upper section. In this case, the surgeon can manually move the lower section in the direction of the beam path by grasping the protrusion and pulling it upward in the direction of the microscope, so that the lower section moves into the upper section. Advantageously, for this purpose, two opposing protrusions can also be implemented on the lower section, each engaging in a mutually opposing longitudinal slot on the upper section. The surgeon can advantageously use a facility to manually move the lower section away from the eye in the direction of the beam path when the optical unit is pivoted out of the beam path. Specifically, if the lens is particularly close to the eye to be operated on, the lens can be manually moved out of the eye's danger zone, and the optical unit can be pivoted out of the beam path in a subsequent manual movement. The same applies to the reverse movement of the optical unit into the beam path. In this case, a corresponding movement of the microscope is no longer required. The positioning device can include a drive unit, by means of which the position of the further optical element can be set in the longitudinal direction of the beam path. The drive unit can be operated purely manually or electrically. It is important that the further optical element can be displaced and positioned along the beam path by means of the drive unit. In this regard, it is also advantageous if the drive unit is self-locking. If the further optical element is accommodated in a lens barrel, the drive unit can also be implemented at least partially or completely on the lens barrel. The drive unit can be mounted on the connecting device above the pivot mechanism and / or on the lens barrel below the pivot mechanism. Thus, the drive unit can be mounted solely on the lens barrel, or it can be mounted on both the connecting device and the lens barrel. Depending on the design of the drive unit, it may be advantageous to implement only a portion of the drive unit on the lens barrel, so that the surgeon's work is not hindered by protruding components of the viewing device. The viewing device may include a shielding unit for shielding the optical path of the positioning unit, wherein the shielding unit may be formed by at least one optical shield or a closed lens barrel. For example, the positioning device and the receiving device may implement such a closed lens barrel. Advantageously, this prevents light sources used during eye surgery, stray light, or the like from entering the beam path and undesirably affecting the image of the eye observed by the surgeon through the optical unit. This prevents possible differences in brightness, reflections, or the like. The drive unit can include a stepper motor, which can be coupled to a coupling of the drive unit to the lens barrel via a belt drive or a transmission. In this case, the stepper motor can be an electric motor, which can be used to perform a defined number of rotations until the further optical element is in the desired position in the lens barrel. For this purpose, the lens barrel can be rotatable in sections, so that the rotation of the stepper motor can be transferred to the lens barrel via the belt drive and / or the transmission. The drive unit can include, for example, a sleeve in the lens barrel, which is embodied with a thread or a spiral and is connected to the belt drive and / or the transmission via a coupling. In this case, the rotation of the sleeve, which can be moved by means of the stepper motor, can cause the further optical element to be raised or lowered and / or moved along the beam path. The coupling can be separated or connected by means of a pivot mechanism. This is particularly advantageous if a stepper motor with a belt drive or transmission is arranged on the connecting device above the pivot mechanism. In this case, the coupling can be implemented between the connecting device and the lens barrel in such a way that the coupling is separated when the lens barrel is pivoted out of the beam path and connected when the lens barrel is pivoted into the beam path. The coupling can be implemented as a nonpositive, form-fitting, and / or friction coupling. If the coupling is a magnetic coupling consisting of two rings that can transfer torque by means of magnets, it is advantageous, wherein the other optical element can be moved by means of the rotation of the lens barrel. The two coaxial rings can each have a number of magnets that exert magnetic forces on each other in such a way that the rings attract each other and thus transfer torque. The magnets can be placed on the axial end faces of the respective rings at regular intervals. The magnetic poles of the magnets of the respective rings can alternate so that the rings are in a defined relative position when the coupling is closed. It is particularly advantageous if a gap is created between the rings, because in this case the rings and / or the coupling do not have to contact each other to transfer torque. This gap can be used to insert a sterile cover into the coupling and / or between the lens barrel and the connecting device. The positioning unit may comprise a control device, wherein the control unit may be implemented to detect the pivoting of the optical unit out of or into the beam path and to transmit this to the microscope. The swinging into or out of the optical unit and / or the lens barrel can be easily detected by means of sensors of the control device. In this case, the control device can signal to the microscope whether the optical unit is swung into or out of the beam path. If the microscope is equipped with a so-called inverter, the microscope can move the inverter into or out of the beam path within the microscope. In this case, a beam transposition and a mirror image of the intermediate image of the lens can be generated by means of the inverter, so that when the optical unit is swung into the beam path, the image of the eye is presented to the surgeon in the correct position. The positioning unit includes a control device, the rotation of the lens barrel can be detected by means of a sensor in the control device, and the drive unit can be controlled by means of the control device in such a way that the drive unit can move the other optical element to a desired position in the longitudinal direction of the beam path. The sensor can be, for example, a Hall sensor mounted on the drive unit and / or the lens barrel. Markings, a number of markings in the form of a scale, or the like can be arranged on the lens barrel so that the rotation and position of the other optical element in the longitudinal direction of the beam path can be detected by means of the sensor. This then enables the position of the other optical element along the adjustment range to be detected. For example, if the lens barrel is unintentionally rotated or the connection device to the microscope objective is rotated while the optical unit and / or lens barrel is pivoted out of the beam path, then when the other optical element pivots into the beam path, the other optical element is no longer in the desired position and / or focus (as set by the surgeon before pivoting out). With the help of the drive unit, the control unit can now move the optical element to the desired position and / or previously set focus of the optical unit. In this case, it is no longer necessary for the surgeon to actuate the drive unit to correct the changed setting of another optical element. The microscope according to the present invention comprises the observation device according to the present invention. Further advantageous embodiments of the microscope are provided by referring back to the description of the features of the appended claims of claim 1. In the method according to the invention for observing an eye using an observation device, an optical unit is positioned in the beam path of a microscope between the objective lens of the microscope and in front of the eye to be observed by means of a positioning unit of the observation device. The positioning unit comprises a connecting device, a positioning device, a receiving device, and an optical unit. The optical unit comprises a lens for observing the fundus of the eye and another optical element. The positioning unit comprises a pivot mechanism, by means of which the optical unit is pivoted out of or into the beam path. The positioning unit is coupled to the microscope by means of the connecting device. The lens is mounted on the positioning unit by means of the receiving device. The receiving device is made at least predominantly, preferably completely, of plastic material. The lens barrel of the positioning device is pivoted, the lens barrel being mounted on the pivot mechanism and being made at least predominantly or completely of metal. With regard to the advantages of the method according to the invention, reference is made to the description of the advantages of the observation device according to the invention. Another optical element can be used to correct for refractive anomalies of the eye. Since this allows the intermediate image of the lens to be focused and thus adjust the beam path of the microscope, this can also be corrected with the help of another optical element. Other advantageous embodiments of the method are provided by referring back to the description of the features of the appended claims of technical solution 1. Hereinafter, preferred embodiments of the present invention are explained in more detail with reference to the accompanying drawings. picture 1 to picture The combination of FIG8 shows an observation device 10 having a positioning unit 11 for positioning an optical unit 12 (not shown in greater detail in the present case) in the beam path 13 of a microscope. The observation device 10 can be adjusted on a microscope so that it is located between the microscope objective and in front of the eye to be observed. The positioning unit 11 comprises a connecting device 14, a positioning device 15, a receiving device 16, and the optical unit 12. The optical unit 12 consists of an ophthalmoscope lens 17 and a lens with positive refractive power or a reducing lens 18. In the present case, the ophthalmoscope lens 17 is used to observe the fundus of the eye, and the reducing lens 18 is used to adjust the beam path 13 of the microscope to the intermediate image of the ophthalmoscope lens 17 (not visible in the present case). The positioning unit 11 also comprises a pivot mechanism 19, by means of which the optical unit 12 can be pivoted into or out of the beam path 13. picture 1 to picture 3. picture 5 and picture 6 shows the positioning device 15 which is swung together with the optical unit 12 into the beam path 13, and picture 4. picture 7 and picture 8 shows the positioning device 15 which is pivoted together with the optical unit 12 out of the beam path 13 . Furthermore, the positioning unit 11 can be coupled to a microscope by means of a connecting device 14. In the present case, the connecting device 14 is composed in particular of a receptacle 20 with a guide rail 21 and a clamping screw 22 and can be adapted to the objective of the microscope in such a way that the objective is directly adjacent to the upper side 23 of the connecting device 14. The receiving device 16 is made almost entirely of plastic and accommodates the ophthalmoscopic lens 17. The receiving device 16 is adapted to the positioning device 15. The positioning device 15 is essentially made of metal. By means of a pivot mechanism 19, which in the present case is realized by a hinge 25, the lens barrel 24 of the positioning device 15 can be pivoted by 90 degrees from an essentially vertical position in the beam path 13 out of the beam path 13 in such a way that the beam path 13 is cleared. The hinge 25 is realized with a guide 26 which allows the positioning device 15 to be latched in place. picture 2 and picture 4. Therefore, the positioning device 15 can be reliably fixed at the respective positions. The receiving device 16 is completed by a further lens barrel 27, which in the present case consists of an upper section 28 and a lower section 29. Furthermore, a compression spring 30 is inserted into the upper section 28 and fixed therein by means of a ring 31. The ophthalmoscopic lens 17 is held on the lower end 32 of the receiving device 16. Furthermore, the lower section 29 is realized with two projections 33, each of which passes through a longitudinal groove 34 in the upper section 28. The compression spring 30 is in contact with the upper edge 35 of the lower section 29, which rests on a step 37 with an annular shoulder 36 on the lower end 38 of the upper section 28. In the event of a collision between the lower end 32 and the eye, the lower section 29 can now be pushed into the upper section 28 against the spring force of the compression spring 30. Furthermore, it is also possible to grasp the projection 33 by hand and push the lower section 29 into the upper section 28 in order to create a sufficient distance relative to the eye when the receiving device 16 is to be pivoted together with the positioning device 15 . The receiving device 16 is implemented with connecting elements 39 that engage in grooves 40 in the lens barrel 27 and latch there. The connecting elements 39 are implemented on tabs 41 on the upper end 42 of the upper section 28. The tabs 41 allow the connecting elements 39 to be elastically mounted transversely to the beam path 13 and can be manually actuated. Pressing together and / or screwing in the tabs 41 then allows the receiving device 16 to be removed from the lens barrel 24. The lens barrel 24 is basically composed of an outer sleeve 43 and an inner sleeve 44, which is rotatably mounted on a bearing 45 in the lens barrel 24. A mount 46 with a reduction lens 18 is inserted into the inner sleeve 44. In addition, a spiral tube 47 is implemented in the inner sleeve 44 and a groove 48 is implemented in the outer sleeve 43. Relative protrusions 49 on the mount 46 pass through the spiral tube 47 and the groove 48 respectively. The rotation of the inner sleeve 44 relative to the outer sleeve 43 enables the mount 46 and the reduction lens 18 to move along this type of beam path 13. The user can see the position of the reduction lens 18 in the lens barrel 28 on the circumferential surface 50 of the lens barrel 24. In the present case, the protrusion 49 can be seen in the groove 48. When using the observation device 10, the ophthalmoscope lens 17 can first be aligned with the eye by adjusting the height of the microscope. Subsequently, the reduction lens 18 can be set by adjusting its position in the lens barrel 24 in such a way that the intermediate image of the ophthalmoscope lens 17 can be clearly focused by means of the microscope. The rotation of the inner sleeve 44 in the outer sleeve 43 is achieved by the drive unit 51 of the positioning device 15. In the present case, the drive unit 51 is placed on the connecting device 14 and comprises a stepper motor 52, a belt drive 53 and a coupling 54. In the present case, the drive wheel 55 of the belt drive 53 is connected to an output sleeve 57 in the connecting device 14 via a belt 56. The output sleeve 57 coaxially surrounds the beam path 13 and is rotatably mounted in a housing 59 of the connecting device 14 by means of a bearing 58. The coupling 54 is implemented as a magnetic coupling 60, with an axial end face 61 of the inner sleeve 44 and an opposite axial end face 62 of the output sleeve 57 each having a magnet 63 embedded therein. The magnets 63 are arranged with alternating polarity in such a way that the opposing magnets 63 exert a magnetic force on each other so that torque can be transferred to the inner sleeve 44 when the output sleeve 57 rotates. The control device 64 of the positioning unit 11 is located in the housing 59 and can be used to control and detect the rotation of the lens barrel 24 and / or the inner sleeve 44. Even if the observation device 10 is rotated or rotated around the beam path 13 on the microscope, for example by manually performing a rotation, if the reduction lens 18 has been adjusted and / or moved along the beam path 13 by means of this rotation, it is also possible to bring the reduction lens 18 into the desired position in the longitudinal direction of the beam path 13 by means of the stepper motor 52. For this purpose, the control device 64 can be equipped with a sensor for detecting this rotation (not shown in the present case). In addition, the control device 64 is provided with a connection 65 for connecting to a power supply, a foot switch (not shown in the present case) and a microscope. Figure 9 and picture 10 shows the accommodating device 16 and the cover unit 66 of observation device 10. Cover unit 66 is made of plastic material and is made of upper sterile cover 67 and lower sterile cover 68. Utilize upper sterile cover 67, can cover the end surface 69 and upper circumferential surface 70 of lens barrel 24. Utilize lower sterile cover 68, can cover the circumferential surface 50 and part hinge 25 of lens barrel 24. Upper sterile cover 67 has protrusion 71, and it is engaged on lens barrel 24 and realizes upper annular shoulder 72. Therefore, upper sterile cover 67 can be latched on upper annular shoulder 72. In addition, tab 73 is arranged on upper sterile cover 67 to remove upper sterile cover 67 manually. In addition, groove 74 is realized in upper sterile cover 67, and pin 75 on connecting device 14 passes through these grooves 74 in the installation position. The pin 75 forms a stop 76 for the lens barrel 24 and a gap 77 between the lens barrel 24 and the connecting device 14 , in which gap 77 a circular cover area 78 of the upper sterile cover 67 is accommodated and secured against rotation by means of the pin 75 . Like the upper sterile cover 67, the lower sterile cover 68 is integrally formed and has a projection 79 that engages in the lower annular groove 80 of the lens barrel 24. Therefore, the lower sterile cover 68 can be fixed to the lens barrel 24 by a latch. In addition, a tab 81 is implemented on the lower sterile cover 68, wherein the lower sterile cover 68 can be removed from the lens barrel 24 by means of the tab 81. The tab 81 is implemented with a weak line 82 in the lower cover 68 so that a tear strip 83 is formed, which leads to the destruction of the lower sterile cover 68 when the tab 81 is manually actuated. Therefore, it is ensured that the cover unit 66 is not reused again after removal. In addition, the plastic material of the cover unit 66 is partially transparent. Since the cover unit 66 completely covers the lens barrel 24, it is not necessary to sterilize the lens barrel 24 after the operation has been performed. After the operation, the cover unit 66 can be removed and replaced with a new, sterile cover unit 66 that has not yet been used. This also applies to the container 16 with the ophthalmoscopic lens 17, so that in this case, unintentional reuse and sterilization are also excluded. Therefore, after the operation has been performed, the viewing device 10 can be quickly prepared for the subsequent operation by replacing the cover unit 66 and the container 16, without the need for time-consuming sterilization of the viewing device 10. 10: Observation device 11: Positioning unit 12: Optical unit 13: Beam path 14: Connecting device 15: Positioning device 16: Receiving device 17: Ophthalmoscope lens 18: Reducing lens 19: Pivoting mechanism 20: Receiving part 21: Guide rail 22: Clamping screw 23: Upper side 24, 27: Lens barrel 25: Hinge 26: Guide 28: Upper section 29: Lower section 30: Compression spring 31: Ring 32: Lower end 33, 49, 71, 79: Protrusion 34: Longitudinal groove 35: Upper edge 36: Annular shoulder 37: Step 38: Lower end 39: Connecting element 40: Groove 41, 73, 81: Tab 42: Upper end 43: Outer sleeve 44: Inner sleeve 45, 58: Bearing 46: Mount 47: Helical tube 48: Groove 50: Circumferential surface 51: Drive unit 52: Stepper motor 53: Belt drive 54: Coupling 55: Drive pulley 56: Belt 57: Output sleeve 59: Housing 60: Magnetic coupling 61, 62: Axial end face 63: Magnet 64: Control device 65: Connecting element 66: Cover unit 67: Upper sterile cover 68: Lower sterile cover 69: End surface 70: Upper circumferential surface 72: Upper annular shoulder 74: Groove 75: Pin 76: Stop 77: Gap 78: Circular cover area 80: Lower annular groove 82: Weakness line 83: Tear strip In the diagram: FIG1 shows a perspective view of an observation device; FIG2 shows a side view of the viewing device with a shielding unit; FIG3 shows a side view of the viewing device without the shielding unit; FIG4 shows a side view of the viewing device with the positioning device swung out of the beam path; FIG5 shows a longitudinal cross-sectional view of an observation device having a shielding unit; FIG6 shows a longitudinal cross-sectional view of the observation device without the shielding unit; FIG7 shows a perspective view of the viewing device with the positioning device and the shielding unit swung out of the beam path; FIG8 shows a perspective view of the viewing device without the shielding unit and the receiving device; FIG9 shows a longitudinal cross-sectional view of the shielding unit and the receiving device; FIG. 10 shows an exploded view of the shielding unit and the receiving device. 10: Observation device 11: Positioning unit 12: Optical unit 13: Beam path 14: Connecting device 15: Positioning device 16: Container 17: Ophthalmoscope inspection lens 18: Zoom out lens 19: Pivot mechanism 51:Drive unit 52: Stepper Motor 53: Belt drive 55: driving wheel 56: Belt 57: Output sleeve 58: Bearing 64: Control device 65: Connector 66: Cover unit 72: Upper annular shoulder 75: Pin

Claims

1. An observation device (10) having a positioning unit (11) for positioning an optical unit (12) in a beam path (13) of a microscope between an objective lens of the microscope and an eye to be observed, the positioning unit comprising a connecting device (14), a positioning device (15), a receiving device (16) and the optical unit, the optical unit comprising a lens for observing the fundus of the eye and another optical element, the positioning unit comprising a pivoting mechanism (19) by means of which the optical unit can pivot away from or into the beam path, the positioning unit being coupled to the microscope by means of the connecting device, the lens being adapted to the positioning device by means of the receiving device, the receiving device being at least primarily, preferably entirely, made of plastic material, characterized in that the positioning device has a lens barrel (24) pivotally mounted on the pivoting mechanism, the lens barrel being at least primarily or entirely made of metal.

2. The observation device of claim 1, characterized in that the other optical element is disposed below the pivoting mechanism (19).

3. The observation apparatus of claim 1 or 2, characterized in that the other optical element can be moved relative to the microscope in the longitudinal direction of the beam path (13) by means of the positioning device (15).

4. The observation device according to claim 1 or 2, characterized in that the lens is an ophthalmoscope lens (17), the other optical element is at least one lens (18) having positive refractive power and used to adjust the beam path, and the lens in the lens barrel (24) is movably disposed below the pivoting mechanism (19) in the longitudinal direction of the beam path.

5. The observation device as claimed in claim 1 or 2, characterized in that the observation device (10) includes a cover unit (66) made of plastic material for aseptically covering the pivotable lens barrel (24) of the positioning device (15).

6. The observation device according to claim 5, characterized in that the cover unit (66) has an upper sterile cover (67) for at least partially covering one end surface (69) of the lens barrel (24) and a lower sterile cover (68) for at least partially covering one circumferential surface (70) of the lens barrel.

7. The observation device of claim 5, characterized in that the cover unit (66) may be implemented with at least one connecting element (71, 79), which needs to be destroyed when the cover unit is separated from the positioning device (15).

8. The observation device of claim 5, characterized in that the cover unit (66) has at least one tear strip (83) by means of which the cover unit can be at least partially destroyed.

9. The observation device of claim 1 or 2, characterized in that the receiving device (16) is implemented with at least one connecting element (39), which needs to be destroyed when the receiving device is separated from the positioning device (15).

10. The observation device according to claim 1 or 2, characterized in that the receiving device (16) is implemented having another, preferably conical, lens barrel (27).

11. The observation device of claim 10, characterized in that the other lens barrel (27) is composed of an upper section (28) and a lower section (29), the lower section being loosely mounted on the upper section in such a way that the lower section can be inserted into the upper section or in a spring-loaded manner.

12. The observation device of claim 11, characterized in that at least one manually actuable protrusion (33) is implemented on the lower section (29), the protrusion passing through a longitudinal groove (34) implemented in the upper section (28) and being movable along the longitudinal groove.

13. The observation device as claimed in claim 1 or 2, characterized in that the positioning device (15) has a driving unit (51) by means of which the position of one of the other optical elements can be set in the longitudinal direction of the beam path (13).

14. The observation device of claim 13, characterized in that the drive unit (51) is disposed above the pivot mechanism (19) on the connecting device (14) and / or below the pivot mechanism on the lens barrel (24).

15. The observation device of claim 1 or 2, characterized in that the observation device (10) includes a shielding unit for shielding one of the optical paths of the positioning unit (11), the shielding unit being composed of at least one optical shielding or sealing lens barrel (24, 27).

16. A microscope having an observation device (10) as described in any one of claims 1 to 15 above.

17. A method for observing an eye using an observation device (10), wherein an optical unit (12) is positioned in a beam path (13) of a microscope between an objective lens of the microscope and an eye to be observed by means of a positioning unit (11) of the observation device, the positioning unit comprising a connecting device (14), a positioning device (15), a receiving device (16) and the optical unit, the optical unit comprising a lens for observing a fundus of the eye and another optical element, the positioning unit comprising a pivoting mechanism (19) by means of the pivoting mechanism pivoting away from or into the beam path, the positioning unit being coupled to the microscope by means of the connecting device, the lens being adapted to the positioning device by means of the receiving device, the receiving device being at least primarily, preferably entirely, made of plastic material, characterized in that a lens barrel (24) of the positioning device (15) is pivoted, the lens barrel (24) being disposed on the pivoting mechanism, the lens barrel being at least primarily or entirely made of metal.

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