DE9418864U1 - Device for determining and marking the corneal vertex - Google Patents

Description

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Description: 94075 G

Device for determining and marking the corneal vertex

The present invention relates to a device for determining and marking the corneal vertex according to the preamble of claim 1.

To correct the refractive power of a defective eye, in particular to correct short-sightedness, it is known to make radial incisions in the cornea of the patient's eye, for example with a special scalpel. This type of procedure is called radial keratotomy. The resulting changes in the mechanical properties of the cornea cause the cornea to flatten and thus correct any short-sightedness that may be present. If this type of procedure is to be carried out using the surgical microscope, the corneal vertex must be found and marked so that it is visible to the surgeon. The "point where the visual axis penetrates" through the cornea is referred to below as the corneal vertex. Only if this point is precisely identified can a reliable incision be made.

The determination of the corneal vertex using a light beam reflected from the cornea is described, for example, in the publication "Highlights of Ophthalmology Letter, Vol. XIII, No. 5, 1985" by B.F. Boyd on pages 1-14. This method is also known from the publication "0. Müller: Possibilities and limits of a visual axis marking of the cornea using an operating microscope", Klin. MbI. Augenheilkunde 191 (1987), pp. 74-77".

The patient looks into the paraxial microscope illumination and the surgeon focuses on the light source image that is reflected by the cornea. The corneal vertex sought is located in this type of illumination.

arrangement then in a specific, defined relative position to the light source image.

Such a method is not ideal for an illumination device of a surgical microscope, which directs the illumination light at least partially at a defined angle to the optical axis of the main objective towards the cornea, as this results in a certain inaccuracy.

In order to precisely mark the corneal vertex, it is also known, for example in the case of slit lamps, to place a separate light source in the observation beam path and to project this light source onto the patient’s cornea in order to generate the required corneal reflex.

Another possibility for generating a corneal reflex and determining the corneal vertex is also described, for example, in the applicant's US 4,614,411. Although this method cannot be considered highly precise, it often delivers sufficient results. The exit surface of a fiber optic light guide is placed between the two stereoscopic observation beam paths and the exit surface is projected onto the patient's cornea; the surgeon determines the position of the corneal vertex from the reflex image. A separate light source is therefore also required here.

For an illumination device of a surgical microscope in which light also hits the cornea at a defined angle to the optical axis, as known from DE 40 28 605 of the applicant, the options mentioned for marking the corneal vertex are unsuitable or not precise enough. The method known from US 4,614,411 would represent an acceptable compromise in terms of the required accuracy, but requires greater effort due to the separate light source.

The object of the present invention is therefore to create a device for determining and marking the corneal vertex in a surgical microscope with an illumination device that is as inexpensive as possible and allows at least part of the illumination light to strike the cornea at a defined angle to the optical axis of the main objective, so that a reliable determination and marking of the corneal vertex is possible during eye operations.

This object is achieved by a device for determining and marking the corneal vertex with the characterizing features of claim 1.

The device according to the invention for determining and marking the corneal vertex in a surgical microscope allows not only the variable choice of the angle of incidence of the illumination beam path but also the marking of the corneal vertex during eye operations. The projection of an almost point-shaped light source image onto the patient's cornea allows the corneal vertex to be determined and marked with the accuracy of known methods with minimal additional technical effort.

Further advantages and details of the device according to the invention emerge from the following description of embodiments with reference to the accompanying figures.

This shows

Figure la

and Ib a first embodiment of the inventive device for determining and marking the corneal vertex in a surgical microscope in two different views;

Figure 2a

and 2b a second embodiment of the device according to the invention for determining and marking the

Corneal vertex in a surgical microscope in two different views;

Figure 2c

and 2d each show an embodiment of a suitable aperture for arrangement in the embodiment of Figure 2b;

Figure 3 shows a view of a suitable aperture device within the device according to the invention for determining and marking the corneal vertex in a surgical microscope.

Figure la shows a schematic side view of the device according to the invention for determining and marking the corneal vertex in a surgical microscope. (1) here designates the one-piece main objective of the surgical microscope. The other observation-side optical elements of the surgical microscope, such as magnification changers and binocular tubes, are only indicated schematically via the two optical elements (5a, 5b) and are designed in a known manner. According to DE 40 28 605, the lighting device comprises two deflection elements (2, 3), between which a variable-position aperture (4) is arranged. The two deflection elements (2, 3) in conjunction with the variable-position aperture element (4) allow the illumination light to fall on the surgical field at various angles. On the lighting side, a fiber optic light guide (6) with a front diaphragm (7) and two optical imaging elements (8, 9) is also provided, whereby, of course, simpler or more complex imaging elements can also be used here. In the illustrated embodiment, a diaphragm device (10) is arranged between the two optical imaging elements (8, 9) of the lighting device. The diaphragm device (10) is designed as a pinhole diaphragm in the illustrated embodiment, which only allows part of the illumination beam path (11) to strike one of the two deflection elements (2, 3). This creates the marking beam path for the patient.

Cornea. The aperture device (10) has an aperture opening (15) at a point in the beam path, which defines a marking beam path (11) that neither coincides with an axis of symmetry of the illumination beam path nor with an axis of symmetry of the stereoscopic observation beam paths.

Figure 1b shows a top view of the main objective (1) including the two deflection elements (2, 3) from Fig. 1a. The two stereoscopic observation pupils (13a, 13b) can also be seen. The surface (14) on the deflection element (2) exposed to the marking beam path is also shown.

The light source (not shown), whose radiation is coupled into the fiber optic light guide (6), is advantageously adjustable in terms of intensity in order to enable optimal adaptation to a wide variety of operating conditions. Furthermore, the aperture device (10) can be optionally pivoted into the illumination beam path, since such a marking is not required for all eye surgical procedures.

It is also possible to provide several such aperture devices with differently arranged or dimensioned aperture openings (15) on an aperture turret and to swing a suitable aperture device into the illumination beam path depending on the application. Furthermore, in order to optimize the light source image on the patient's eye, it is possible to insert optically effective elements into the aperture opening (15), such as a suitable lens or a diffuser, etc.

An alternative embodiment of the lighting device according to the invention is shown in Figures 2a and 2b. This embodiment differs from the arrangement proposed in Figures 1a and 1b only in the different design of the two deflection elements (22,

23) in the illumination beam path. One of the two deflection elements (22, 23) that allows a portion of the illumination light to strike the surgical field axially is now triangular in the direction of the center of the main objective. The aperture device (30) in the illumination beam path is dimensioned or arranged in such a way that this deflection element (22) is exposed to the marking beam path (31) in the triangular or pointed part.

Furthermore, a diaphragm (37) that can be moved along the arrow is arranged in the illumination beam path in front of the deflection element (22), via which certain parts of the illumination light can be selectively blocked out. Various diaphragm shapes can be implemented here, as the two top views of possible embodiments of the diaphragm (37) in Figures 2c and 2d illustrate.

Furthermore, in this embodiment, it is possible to arrange the deflection element (22) so that it can be moved at least in one plane, as is illustrated by the associated arrow. By positioning the deflection element (22) accordingly, an exact overlap of the illumination and observation beam paths can be achieved. At the same time, the diaphragm device (30) is rotated by an angle α around the optical axis (32) of the illumination beam path, so that the diaphragm opening is ultimately oriented in a centered manner to the observation beam path. In this embodiment, the corneal reflex image is exactly identical to the corneal viewing point when viewed monocularly through just one of the two stereoscopic observation beam paths.

A view of the pinhole diaphragm (30) in Figure 2a is shown in Figure 3. The arrangement of the diaphragm opening (45) is clearly visible, which does not coincide with the optical axis of the illumination beam path (.32).

The determination of the actual corneal vertex from the point-like reflex image is finally carried out by the surgeon in the same way as described in the cited publications, provided the optical data are known.

Claims (11)

Expectations: 1. Device for determining and marking the corneal vertex in a surgical microscope with an illumination beam path which deflects at least a portion of the illumination light at a defined angle to the main objective in the direction of the eye being observed and for this purpose comprises at least one deflection element, characterized in that a diaphragm device (10, 30) is arranged in the illumination beam path, which allows only a portion of the illumination beam path to strike the deflection element (2, 22) and thus defines a marking beam path (11, 31). 2. Device according to claim 1, characterized in that the marking beam path (11, 31) defined by the aperture device (10, 30) runs along an axis that neither coincides with an axis of symmetry of the illumination beam path nor with an axis of symmetry of the observation beam paths. 3. Device according to claim 2, characterized in that the aperture device (10, 30) can be optionally -Illumination beam path can be swiveled in. 4. Device according to claim 2, characterized in that the deflection element (2, 22) acted upon by the illumination beam path through the aperture device (10, 30) is designed triangularly in one direction, the triangle tip being acted upon by the marking beam path (11, 31). 5. Device according to at least one of the preceding claims, characterized in that a perforated diaphragm is provided as the diaphragm device (10, 31). 6. Device according to at least one of the preceding claims, characterized in that the light source of the illumination beam path is adjustable in terms of intensity. 7. Device according to at least one of the preceding claims, characterized in that several aperture devices (10, 30) of different sizes, shapes and positions are arranged on an aperture turret, which enables various aperture devices (10, 30) to be swiveled in as desired. 8. Device according to at least one of the preceding claims, characterized in that at least one displaceable diaphragm (37) is arranged in the illumination beam path in front of at least one deflection element (22), via which certain portions of the illumination light can be selectively blocked out. 9. Device according to at least one of the preceding claims, characterized in that at least one of the deflection elements (22) is arranged displaceably in at least one plane. 10. Device according to at least one of the preceding claims, characterized in that the diaphragm device (10, 30) is arranged to be rotatable about the axis of the illumination beam path. 11. Surgical microscope, particularly suitable for ophthalmic surgery, characterized by an integrated device according to at least one of the preceding claims.