Ophthalmological Treatment Apparatus

Abstract

Disclosed is an ophthalmological treatment apparatus for modifying a shape of a corneal surface of a human eye. The apparatus includes a surgical laser device for implementing tissue cuts. The apparatus further includes a computerized control device in operative coupling with the surgical laser device, the control device being designed to control the laser device to implement tissue cuts according to a cut geometry with a primary tissue cut and a secondary tissue cut, wherein the primary tissue cut is a relief cut and extends into the depth of the conical eye tissue, and wherein the secondary tissue cut lies within the conical eye tissue, such that the secondary tissue cut adds to the relieving effect of the primary tissue cut.

Claims

1. An ophthalmological treatment apparatus for modifying a shape of a corneal surface of a human eye of a patient, comprising: a surgical laser device for implementing tissue cuts; and a computerized control device in operative coupling with the surgical laser device, the control device being designed to control the surgical laser device to implement tissue cuts according to a patient-specific cut geometry with a primary tissue cut and a secondary tissue cut, wherein the primary tissue cut is a relief cut and extends into a depth of a tissue and includes a patient-specific arc length, wherein the secondary tissue cut lies within the tissue, such that the secondary tissue cut adds to the relieving effect of the primary tissue cut, wherein the secondary tissue cut is arranged such that it extends in the tissue an area of increased mechanical stress resulting from the primary tissue cut, thereby increasing a conical tissue deformation resulting from the primary tissue cut, and wherein a patient-specific cut geometry parameter of the patient-specific cut geometry is at least one of: an arc length, a radius of the primary tissue cut, a depth of the primary tissue cut, a width of the secondary tissue cut, or an axis with respect to which the primary and secondary tissue cuts are centered.

2. The apparatus of claim 1, wherein the primary tissue cut and the secondary tissue cut meet or intersect along a joint line.

3. The apparatus of claim 1, further comprising memory for storing a plurality of predefined cut geometry templates.

4. The apparatus of claim 3, wherein the patient-specific cut geometry is computed by applying the patient-specific cut geometry parameter to one of the plurality of predefined cut geometry templates.

5. The apparatus of claim 4, further comprising a user interface for receiving a selection of the patient-specific cut geometry parameter by an operator of the apparatus.

6. The apparatus of claim 1, wherein the surgical laser device includes a femtosecond laser source.

7. The apparatus of claim 1, wherein the primary tissue cut extends to an outer tissue surface.

8. The apparatus of claim 1, wherein the primary tissue cut and the secondary tissue cut are spatially curved.

9. The apparatus of claim 1, wherein the primary tissue cut and the secondary tissue cut are perpendicular with respect to each other.

10. The apparatus of claim 1, wherein the secondary tissue cut extends in a constant distance from a posterior corneal surface.

11. The apparatus of claim 1, wherein the control device is designed to control the surgical laser device to implement the secondary tissue cut prior to implementing the primary tissue cut.

12. The apparatus of claim 1, wherein the control device is designed to control the surgical laser device to start implementing the primary tissue cut at a starting position within the tissue and advance towards the outer tissue surface.

13. The apparatus of claim 1, wherein a tissue bridge remains between the primary tissue cut and the secondary tissue cut, wherein the patient-specific cut geometry parameter of the patient-specific cut geometry includes a width of the tissue bridge.

14. A method comprising: implementing, by a surgical laser device, tissue cuts; controlling, by a computerized control device in operative coupling with the surgical laser device, the surgical laser device to implement the tissue cuts according to a patient-specific cut geometry with a primary tissue cut and a secondary tissue cut, wherein the primary tissue cut is a relief cut and extends into a depth of a tissue, wherein the secondary tissue cut lies within the tissue, such that the secondary tissue cut adds to the relieving effect of the primary tissue cut, wherein the secondary tissue cut is arranged such that it extends in the tissue an area of increased mechanical stress resulting from the primary tissue cut, thereby increasing a conical tissue deformation resulting from the primary tissue cut, and wherein a patient-specific cut geometry parameter of the patient-specific cut geometry is at least one of: an arc length, a radius of the primary tissue cut, a depth of the primary tissue cut, a width of the secondary tissue cut, or an axis with respect to which the tissue cuts are centered.

15. The method of claim 14, wherein the primary tissue cut and the secondary tissue cut meet or intersect along a joint line.

16. The method of claim 14, further comprising storing, in memory, a plurality of predefined cut geometry templates.

17. The method of claim 15, further comprising applying the patient-specific cut geometry parameter to one of the plurality of predefined cut geometry templates.

18. The method of claim 17, further comprising computing the patient-specific cut geometry based upon the applied patient-specific cut geometry parameter.

19. The method of claim 18, further comprising receiving, by a user interface, a user selection of the patient-specific cut geometry parameter.

20. An apparatus comprising: a surgical laser device configured to implement tissue cuts; and a computerized control device configured to control the surgical laser device to implement tissue cuts according to a patient-specific cut geometry with a primary tissue cut and a secondary tissue cut, wherein the primary tissue cut is a relief cut and extends into a depth of a tissue, wherein the secondary tissue cut lies within the tissue, such that the secondary tissue cut adds to the relieving effect of the primary tissue cut, wherein the secondary tissue cut is arranged such that it extends in the tissue an area of increased mechanical stress resulting from the primary tissue cut, thereby increasing a corneal tissue deformation resulting from the primary tissue cut, and wherein a patient-specific cut geometry parameter of the patient-specific cut geometry is at least two of: an arc length of the primary tissue cut, a radius of the primary tissue cut, a depth of the primary tissue cut, a width of the secondary tissue cut, or an axis with respect to which the primary and secondary tissue cuts are centered.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0053] FIG. 1a-1c illustrate the biomechanical principle of a relief cut into the corneal tissue;

[0054] FIG. 2a-2b illustrate the principle of a cut geometry with a primary tissue cut and a secondary tissue cut;

[0055] FIG. 3 show an ophthalmologic treatment apparatus in a schematic view;

[0056] FIG. 4-4m illustrate exemplary embodiments of cut geometries in a sectional view;

[0057] FIG. 5a-5c illustrate exemplary embodiments of cut geometries in a frontal view.

EXEMPLARY EMBODIMENTS

[0058] Where, with reference to the figures, directional terms such as “top”, “bottom”; “left”, “right”, “above”, or “below” are used, such terms are only intended to guide the reader's view and to improve the understanding of the figures. They are not meant to imply any particular directions and/or relative positions during application, unless stated differently in a specific context.

[0059] In the following, reference is first made to FIG. 1a-FIG. 1c and FIG. 2a-FIG. 2b, illustrating the underlying biomechanical principle of the present disclosure in a simplified one-dimensional model.

[0060] Further in the following description, it is assumed that the eye tissue into which the tissue cuts are implemented is corneal tissue. The considerations and examples, however, also hold true for limbal tissue in an analogue way.

[0061] It is to be understood that the corneal tissue, the intra-corneal tissue stress and the effect from implementing tissue cuts into or within the corneal tissue are three-dimensional. This three-dimensional real world situation may be approximated with good accuracy by a two-dimensional membrane strain model. Since the main effect of the tension is tangential to the cornea surface and perpendicular to the tissue cut projection, it may, in particular for illustrative purposes, be further simplified to a one-dimensional model. This approach is used in the following description.

[0062] FIG. 1a shows a rod of length 1 as one-dimensional model of the corneal tissue 210, with the anterior (outer) cornea surface being referenced 211. Assuming one end (bottom end, not referenced) of the rod to be fixed, the rod is strained with a displacement Δ1 under influence of a force F which results from the intra-ocular pressure. Accordingly, the top end A of the rod is displaced by Δ1. Stress (Force F divided by the cross-section of the rod) and strain (Δ1/1) are constant across the rod. In FIG. 1b, a tissue cut C is implemented that extends from the anterior (outer) cornea surface and into the corneal tissue, traverse to the direction of the force F. The tissue cut C has a depth d as measured from the cornea surface 211 to the (not reference) ground of the cut inside the corneal tissue 210. As best visible in FIG. 1c, the tissue cut C results in a zone B of increased stress and strain at the bottom of the tissue cut C, resulting in a gap 212 that extends from the cornea surface 211 into the corneal tissue 210, and an increased displacement of the corneal tissue 210 (see position of end A in FIG. 1c as compared to FIG. 1a). To this extend, FIG. 1a-FIG. 1c illustrate the situation of a corneal incision procedure as generally known in the art, with the cut C being, e. g., an arcuate incision for the case of arcuate keratotomy.

[0063] In accordance with the present disclosure, an additional tissue cut C′ may be implemented in addition to the tissue cut C as primary tissue cut, as shown in FIG. 2a. The secondary tissue cut C′ extends fully inside the corneal tissue 210 and is traverse to the primary tissue cut C. As best visible in FIG. 2b, the secondary tissue cut C′ results in a larger zone B′ of increased stress, which in turn results in a wider gap 212′ and an increased displacement as compared to a situation with only the primary tissue cut C being implemented (see FIG. 2b as compared to FIG. 1c). With s being the width of the secondary tissue cut as indicated, the effect of the secondary tissue cut C′ increases with s, thereby providing a new additional parameter that may be selected or adjusted to achieve the desired tissue deformation.

[0064] In the following, reference is additionally made to FIG. 3. FIG. 3 shows an exemplary embodiment of an ophthalmologic treatment apparatus 1, 3, in accordance with the present disclosure and in interaction with a human eye (patient eye) 2 in a schematic view.

[0065] For the human eye 2, the cornea 21, the lens 22, the retina 23 and the sclera 29 are shown. Further, the limbus (not separately referenced) is present as transition area between the cornea 21 and the sclera 29. Some cuts or incision, in particular limbal relaxing incisions, LRI, are made in the limbal tissue. A direction from “outer” towards “inner” is a direction from the outer surface of the cornea 21 and the sclera 29 towards the retina 23.

[0066] The ophthalmologic treatment apparatus comprises the control device 1 and the surgical laser device 3 that is exemplarily based on a femtosecond laser source in operative coupling with a projection lens that is part of an application head (components as scanners and beam delivery and shaping optics are not separately shown). From the laser device 3 respective its projection lens, laser radiation is emitted and focused onto a point of the corneal tissue 210 (indicated by radiation cone 32). In a situation of use, the surgical laser device 3 is coupled to the eye 2 via a patient interface 31 that is typically designed for one-way use and couples with the surgical laser device 3 respectively its application head via releasable mechanical coupling and for coupling with the eye 2 respective its sclera 29 and/or cornea 21 via a suction ring 33. Coupling is not mandatory if the laser can compensate for eye movement or is fast enough. The patient interface 31 may be designed to deform the eye surface to a desired shape for the surgical procedure, e. g. planar, spherical or aspherical shape with an applanation-type coupling and a transparent contact body.

[0067] Alternatively, the patient interface 31 may be designed to couple with the eye 2, in particular the cornea 21, via a contact liquid, e. g. saline solution, substantially without causing deformation. An exemplary patient interface is disclosed in the EP2853247.

[0068] The control device 1 is exemplarily shown as being based on a general purpose computing device 15, such as a PC or workstation, in operative coupling with a user interface that includes an input unit 16 (shown with a keyboard and a mouse for exemplary purposes) and an output unit 17 (exemplarily shown as computer monitor with an image area 171).

[0069] Other devices for the input unit 16 and/or the output unit 17 may be used as well. For example, the input unit 16, may include a track ball and/or a touch pad. The output unit 17 may, for example, be or include a beamer or glasses with integrated display, to be worn by an operator.

[0070] The control device 1 includes a number of functional modules 1′, which include interface circuitry for coupling with the surgical laser device 3 via an (typically electrical) operative coupling 4. The control device 1 further includes one or more processors, e. g. microprocessors and/or microcontrollers, for controlling operation of the control device 1 and the ophthalmologic treatment apparatus as a whole in accordance with corresponding program code. The control device 1 further includes volatile and/or non-volatile memory that stores program code and/or data.

[0071] In FIG. 3, the control device is shown as a compact unit. The control device 1 may, however, also be distributed between a number of computing devices, each with particular functional units 1′. The computing devices may be coupled via data interfaces such as a LAN network or USB connection for data transfer and/or between which data may be transferred via physical media, such as CD-ROMS, DVDs, magnetic storage discs, or the like.

[0072] Further, the control device 1 may be fully or partly integrated with the surgical laser device 3.

[0073] In the following, reference is additionally made to FIG. 4a-FIG. 4m, showing a variety of exemplary cut geometries in accordance with the present disclosure in a schematic one-dimensional view, generally similar to the view of before-discussed figures FIG. 1, FIG. 2. The arrow “t” indicates a direction tangential respectively parallel to the cornea surface 211 and pointing radially from the center of the cornea 21 towards the sclera 29. A direction traverse to the cornea surface 211 into the corneal tissue is referred to as depth direction (not referenced) and a distance from the cornea surface as depth. The figures may be considered as cross sectional views of the corneal tissue in the area of the tissue cuts. Generally, geometrical relations such as parallel, perpendicular or mirrored refer to the view as shown.

[0074] FIG. 4a shows a basic embodiment of a cut geometry with the secondary tissue cut being C′ being tangentially symmetric with respect to the primary tissue cut C and perpendicular to the primary tissue cut C. The primary tissue cut C and the secondary tissue cut C′ meet along a joint line, resulting in an overall T-shaped cut geometry in the sectional view. FIG. 4a generally corresponds to FIG. 2a as discussed before.

[0075] The cut geometry as shown in FIG. 4b is similar to the cut geometry as shown in FIG. 4a. The secondary tissue cut C′, however is tangentially displaced with respect to the primary tissue cut C. In this example, the secondary tissue cut is displaced by half of the cut width s (see FIG. 2a) as compared to FIG. 4a, resulting in an L-shaped cut geometry in the cross sectional view. Alternatively, the secondary tissue cut C′ may be displaced by less or somewhat more than half of the cut width. The amount of displacement is a cut geometry parameter that may be selected by a user or automatically.

[0076] The cut geometry as shown in FIG. 4c is similar to the cut geometry as shown in FIG. 4b. The secondary tissue cut C′, however is radially displaced with respect to the primary tissue cut C into the opposite direction as compared to FIG. 4b. The cross sectional cut geometry of FIG. 4c may accordingly be obtained by mirroring the secondary tissue cut C′ with respect to the primary tissue cut C. Similarly, the cut geometries shown and discussed in the following examples may be mirrored in an analogue way.

[0077] For the cut geometry as shown in Fog. 4d, a secondary tissue cut C′ and a further secondary tissue cut C.sub.2′ are present. The secondary tissue cut C′ and the further secondary tissue cut C.sub.2′ are spaced apart from each other in the depth direction, with the distance being bridged by the primary tissue cut C, such that one end of the primary tissue cut C meets with the secondary tissue cut C′ and the other end of the primary tissue cut C meets with the further secondary tissue cut C.sub.2′ along corresponding joint lines. The cross sectional tissue cut geometry is accordingly H-shaped. In contrast to the examples of FIG. 4a-FIG. 4c and FIG. 4f-FIG. 4m, the primary tissue cut does not extend to the anterior (outer) cornea surface 211, but all tissue cuts lie fully within the corneal tissue 210.

[0078] The cut geometry as shown in FIG. 4e is similar to the cut geometry as shown in FIG. 4d. The further secondary tissue cut C.sub.2′, however is tangentially displaced with respect to the primary tissue cut C. It is noted that in cut geometries with a secondary tissue cut C′ and a further secondary tissue cut C.sub.2′, the naming as secondary tissue cut C′ respectively further secondary tissue cut C.sub.2′ is generally arbitrary and may be interchanged.

[0079] The cut geometry as shown in FIG. 4f is similar to the cut geometry as shown in FIG. 4a. The primary tissue cut C, however, extends deeper into the corneal tissue 210 and beyond the secondary tissue cut C′, resulting in the primary tissue cut C and the secondary tissue cut C′ intersecting rather than meeting. The distance by which the primary tissue cut C extends beyond the secondary tissue cut C′ may be a further cut geometry parameter. As explained before, such configuration may be favorably used in order to avoid undesired tissue bridges.

[0080] The cut geometry as shown in FIG. 4g is similar to the cut geometry as shown in FIG. 4a. The primary tissue cut C, however, is inclined rather than perpendicular with respect to the cornea surface 211, resulting in the primary tissue cut C and the secondary tissue cut C′ meeting with an angle different from perpendicular. As explained before, such configuration may be favorably used in order to avoid gaping wounds. The angle of inclination may be a further cut geometry parameter. The cut geometry is such that the joint line is defined by an edge of the secondary tissue cut C′ and the ground of the primary tissue cut C.

[0081] The cut geometry as shown in FIG. 4h is similar to the cut geometry as shown in FIG. 4g. However, the ground of the primary tissue cut C does not meet with an edge of the secondary tissue cut C′, but is somewhat inwardly displaced, resulting in the secondary tissue cut C′ extending beyond the joint line in tangential direction. Further, the primary tissue cut C extends beyond the secondary tissue cut C′ and deeper into the corneal tissue 210. Similar to the cut geometry of FIG. 4f. as discussed before, such arrangement avoids gaping wounds and tissue bridges.

[0082] The cut geometry as shown in FIG. 4i is similar to the cut geometry as shown in FIG. 4g. The primary tissue cut C, however, does not extend to the secondary tissue cut C′, such that the primary tissue cut C and the secondary tissue cut C′ do not meet or intersect, but a tissue bridge 213 remains between them. As explained before, such arrangement is favorable in view of subsequent adjustments. The distance between the ground of the primary tissue cut C and the secondary tissue cut C′, i. e. the width of the tissue bridge 213, may be a cut geometry parameter.

[0083] The cut geometry as shown in FIG. 4j is similar to the cut geometry as shown in FIG. 4g. For the cut geometry of FIG. 4j, however, an inclined primary tissue cut C and a further inclined primary tissue cut C.sub.2 are implemented, that meet with the edges of the secondary tissue cut C′. Such arrangement is also favorable in order to avoid gaping wounds respectively to improve wound closure.

[0084] The cut geometry as shown in FIG. 4k is similar to the cut geometry as shown in FIG. 4j. The primary tissue cut C and the further primary tissue cut C.sub.2, however, are inclined into the opposite direction as compared to the cut geometry of FIG. 4j, that is radially outwards from the secondary tissue cut C′, rather than inwards as in FIG. 4j. This geometry reduces stress gradients, but requires more space.

[0085] The cut geometry as shown in FIG. 4l is similar to the cut geometry as shown in FIG. 4a. The secondary tissue cut C′, however has a peripheral region C.sub.P′ along its edges that extends towards the anterior (outer) cornea surface 211. As explained before, such cut geometry favorably avoids stress peaks along the periphery of the secondary tissue cut C′. A similar further cut geometry is shown in FIG. 4m. While the peripheral regions C′ extend straight in FIG. 4l, they extend towards the anterior (outer) cornea surface in an arc in FIG. 4m. The design and dimensions of the peripheral region C′ may be defined by one or more cut geometry parameters.

[0086] In the following, reference is additionally made to FIG. 5a-FIG. 5c, showing different cut geometries in a frontal view with the viewing direction being along the optical axis onto the cornea surface 211, with the cornea being circumferentially surrounded by the limbus and the sclera 29 (see also FIG. 3). For the sake of conciseness, each of FIG. 5a to FIG. 5c shows two cut geometries. This does not imply, however, that they would be implemented in these specific combinations.

[0087] FIG. 5a shows two cut geometries where the primary tissue cut C.sub.a respectively C.sub.b and the corresponding secondary tissue cut C.sub.a′ respectively C.sub.b′ are perpendicular with respect to each other, and where the secondary tissue cut C.sub.a′ respectively C.sub.b′ is radially symmetrical with respect to the primary tissue cut tissue cut C.sub.a respectively C.sub.b, in accordance with FIG. 4a. For C.sub.a, C.sub.a′, the primary tissue cut C.sub.a projects beyond the secondary tissue cut C.sub.a′ and covers a larger circumferential angle as compared to the secondary tissue cut C.sub.a′. For the cut geometry C.sub.b, C.sub.b′ in contrast, the secondary tissue cut C.sub.b′ projects beyond the primary tissue cut C.sub.b, and accordingly covers a larger circumferential angle as compared to the primary tissue cut C.sub.b. FIG. 5a also shows that opposite geometries do not necessary have to be placed symmetrically to each other and being of same size respectively dimensions.

[0088] FIG. 5b shows two further examples cut geometries with the width of the secondary tissue cut C.sub.c′ respectively C.sub.d′ varying along its arc length. In contrast to the embodiments of FIG. 5c, however, the width of the secondary tissue cut C.sub.c′ respectively C.sub.d′ does not vary continuously, but in discrete steps respectively at discrete positions along the arc length. Secondary tissue cuts of varying width may be used to achieve a homogenous deformation across the eye.

[0089] FIG. 5c shows two examples of cut geometries with the width s of the secondary tissue cut C.sub.e′ respectively C.sub.f′ continuously varies along its arc length. Exemplarily, the primary tissue cuts C.sub.e respectively C.sub.f are shown as being flush with the corresponding second tissue cuts C.sub.e respectively C.sub.f, i. e. cover the same circumferential angle but varying the width s differently.

[0090] FIG. 5a-5c exemplarily show the secondary tissue cuts as single continuous cuts. Alternatively, however, they may be implemented by a number of secondary sub-cuts along it circumferential length, with the secondary sub-cuts being separated by tissue bridges.