Method for attaching a contact lens for ophthalmic surgery

Abstract

Method for attaching a contact lens (12) in ophthalmic surgery, wherein - a contact lens (12) is used which has a lens body (22) accommodated in a mount (37), which has a concave front lens surface (29) designed to be placed on the eye (2), wherein an annular gap (44) is formed at the edge of the front lens surface (29) between the lens body (22) and the mount (37), which, together with the applied eye (2), acts as a suction channel, via which negative pressure can be applied to attach the contact lens (12) to the eye (2), wherein the mount (37) is designed such that when the eye (2) is fully applied to the front lens surface (29) the suction channel between the annular gap (44) and the eye (2) is not yet closed, and - the contact lens (12) is brought close to the eye (2) in such a way that the front surface of the lens (29) initially only touches a central area of the cornea, - with increasing placement, the cornea gradually rests against the complete front surface of the lens (29), wherein in this state the suction channel is not yet closed and in this state an alignment of the contact glass (12) with respect to the eye (2) can be carried out, and after reaching a desired adjustment position the distance between the contact glass (12) and the eye (2) is reduced, whereby the annular gap (44) is closed by the cornea and the eye (2) is fixed with respect to the contact glass (12) by negative pressure.

Description

[0001] The invention relates to methods for attaching a contact lens in ophthalmic surgery, wherein the contact lens has a lens body accommodated in a frame, which has a concave front lens surface designed to be placed on the eye, wherein an annular gap is formed at the edge of the front lens surface between the lens body and the frame, which, together with the applied eye, acts as a suction channel, via which negative pressure can be applied to attach the contact lens to the eye.

[0002] Such a contact glass is shown in WO 2005 / 048 895 A1, which otherwise deals with the attachment of the contact glass to a laser treatment device.

[0003] Contact lenses in ophthalmic surgery are examples of adapters that mechanically couple the laser processing device to an object. This coupling is necessary because the accuracy of the laser beam's positioning within the object generally determines the precision achieved during processing. Only the exact three-dimensional positioning of the laser beam within the processing volume, for example, within the cornea of the eye, enables highly precise processing. Therefore, the object to be processed is fixed using an adapter that ensures a precisely defined position of the object, for example, the eye, relative to the laser processing device. The adapter, commonly referred to as a contact lens in ophthalmic surgery, is thus part of the beam path.If the external shape of the object to be processed is not precisely known, the adapter usually also serves the function of giving the object, as far as possible, a specific shape required for the application of a laser beam. An adapter for coupling a laser processing device to an object is described in DE 103 49 297 A1.

[0004] Because the anterior surface of the cornea of the human eye varies from patient to patient, an adapter in the form of a contact lens is regularly used in laser-assisted eye surgery. US 2001 / 002 184 4 A1 describes a corresponding contact lens that not only fixes the eye but also shapes the anterior surface of the cornea. The US document proposes applying negative pressure between the cornea and the contact lens, which is designed as a lens body, thereby sucking the cornea onto the contact lens. Due to the negative pressure attachment created between the lens body and the cornea, the cornea automatically assumes the shape of the anterior surface of the lens body (the anterior surface refers to the patient).However, this type of attachment is quite uncomfortable for the patient, especially when the barb-like nubs provided in an embodiment of US 2001 / 002 184 4 A1 on the underside of the lens body frame are used, which are intended to achieve an improved attachment of the contact lens to the eye.

[0005] DE 103 53 264 A1 also relates to a contact lens for fixating and coupling the eye to a laser treatment device in ophthalmic surgery. The contact lens has a curved contact surface that is placed on the cornea of the eye to impart a defined curvature. The contact lens is held in a mount that provides an annular gap surrounding the contact surface, through which the adapter is attached to the cornea using negative pressure. This annular gap also couples oblique illumination from the mount onto the eye.

[0006] The invention is based on the object of developing a method for attaching a contact lens of the type mentioned at the outset in such a way that the lens body is securely attached to the eye and the cornea is reliably shaped in a manner that is as gentle as possible for the patient.

[0007] The invention is defined in claim 1. The remaining claims relate to preferred developments.

[0008] The frame of the contact lens used is designed in such a way that when the eye is fully pressed against the front surface of the lens, the suction channel between the annular gap and the eye is not yet closed.

[0009] In contrast to the procedure described in US 2001 / 0 021 844 A1, the cornea is not sucked directly onto the anterior surface of the lens by vacuum, but is applied to the anterior surface of the lens by mechanical pressure. Because the frame is designed in such a way that when the eye is fully applied to the anterior surface of the lens, the suction channel between the annular gap and the eye remains open (i.e. the cornea does not yet cover the annular gap), the contact lens can be precisely aligned with the eye in this state. Only when the contact lens is pressed further towards the eye does the cornea cover the annular gap, closing the suction channel between the annular gap and the eye and enabling the negative pressure fixation. The vacuum applied in the annular gap therefore only serves to fix the eye but does not directly cause the deformation of the cornea. This makes the entire application and fixation process easier to control.

[0010] The vacuum applied through the suction channel only serves to fix the eye in place, but does not directly deform the cornea, as there is no vacuum between the anterior surface of the lens and the cornea. This contact lens is therefore particularly suitable for patients with corneal damage, anomalies, or unhealed incisions from previous ophthalmic surgery in the area of the cornea that will be applied to the anterior surface of the lens. Since there is no negative pressure in this area of the cornea, any damaging effects of the contact lens attachment are now eliminated.

[0011] On the patient side, the transition between the front surface of the lens and the frame (except for the annular gap) is fluid; the frame does not form a discontinuity beyond the annular gap.

[0012] The frame is geometrically designed so that when the eye is already fully apposed to the anterior surface of the lens, the cornea does not yet rest against the frame edge that defines the annular gap, and thus does not yet close the annular gap to form a suction channel. This can be achieved, for example, by ensuring that the axially foremost contour of the frame does not protrude or even recedes relative to a curved surface that the cornea has when the eye is fully apposed to the anterior surface of the lens. The shape of the curved surface depends essentially on the condition of the eye when fully apposed to the anterior surface of the lens. In ophthalmic surgery, this condition is also referred to as the "applanated" condition.

[0013] In a simple design, the curvature surface, relative to which the axially foremost contour of the frame does not protrude or even lags behind, can also be referred to the curvature of the front surface of the lens, so that the axially foremost contour of the frame does not protrude or even lags behind the imaginary extension of the front surface of the lens.

[0014] With the contact lens according to the invention, the natural shape of the cornea can be maintained when the contact lens is in place, which is particularly comfortable for the patient. The eye is placed against the contact lens with minimal deformation at a suitable curvature radius.

[0015] A particularly simple manufacturing process is achieved by forming the annular gap with one or more truncated cone surfaces or conical surfaces on the frame and / or lens body. Such conical surfaces also generally allow for a further design to be easily realized, in which the annular gap tapers away from the eye and converges at an acute angle of ≤ 90°, particularly at the end facing away from the eye.

[0016] This design of the annular gap is also advantageous because it effectively prevents parts of the cornea from being sucked into the upper area of the suction channel, thereby partially blocking it. The introduction of negative pressure into the annular gap is then uncritical, since the entire annular gap always acts as a suction channel, and in particular, the negative pressure connection cannot be blocked by the cornea.

[0017] The contact lens makes it particularly easy to place the contact lens on the cornea, particularly when the curvature of the anterior surface of the lens is somewhat flatter than the cornea. When approaching the contact lens, initially only the central area of the cornea, i.e. the vertex of the cornea, touches the anterior surface of the lens. As the lens is placed closer, the cornea gradually comes into contact with the entire anterior surface of the lens. Even in this state, the suction channel is not yet closed and the patient can still move the eye freely despite partial deformation. In this state, the contact lens can be easily aligned with the eye. Once the desired adjustment position has been achieved, the distance between the contact lens and the patient's eye is reduced slightly, whereby the annular gap is closed by the cornea and the eye is fixed relative to the contact lens by negative pressure.

[0018] The curvature, which is imposed on the eye by the anterior surface of the lens as a desired shape, can be selected depending on the application. In particular, aspheric curvatures are also possible, which allow optical imaging errors to be minimized when applying treatment laser radiation. The anterior surface of the lens can also be spherical with a radius of 5-30 mm. A radius slightly smaller than that of the human cornea, e.g., between 15 and 25 mm, is particularly preferred. This sphericity is easily achieved with the inventive design because, unlike the prior art in the form of US 2001 / 002 184 4 A1, there is no risk of the cornea closing the vacuum suction channel in such a way that the contact lens is only partially attached to the eye.

[0019] It has been shown that when attaching an ophthalmic surgical contact lens using negative pressure, the suction of conjunctiva to the means of negative pressure attachment should be avoided, as otherwise inadequate fixation of the cornea on which the surgical intervention is to be performed may occur. It is therefore expedient, quite independent of the other design of the contact lens and in particular independent of the design of the means of negative pressure attachment, to provide a contact lens for ophthalmic surgery that has an anterior lens surface designed to be placed on the eye and a device for negative pressure attachment of the contact lens to the eye and is further characterized in that a coding element encoding a geometric or optical parameter of the contact lens is provided on the contact lens. Expediently, the geometric or optical parameter is the diameter of the anterior lens surface.The coding element is advantageously attached to the contact lens in such a way that a user, i.e. an eye surgeon, can recognize the desired geometric or optical parameter, for example the desired diameter of the front surface of the lens, from the outside. A barcode, a number or letter identifier, or even a geometric or color code, can be used as a coding element. A contact lens that bears a color marking is particularly preferred, whereby the color marking is assigned to the diameter of the front surface of the lens or to another geometric or optical parameter of the contact lens. If the contact lens is manufactured in two parts, i.e. from a lens body having the front surface of the lens and a frame holding the lens body, the coding element is advantageously arranged on the frame. In the case of color coding, for example, the frame itself can be colored.

[0020] To enable a user to select a contact lens with the desired parameters, the coding is advantageously designed as an optically perceptible coding so that a surgeon can quickly and accurately select the desired contact lens.

[0021] The coding element described can of course be used particularly advantageously with a contact lens of the type described above or below.

[0022] The invention will be explained in more detail below by way of example with reference to the drawings. In the drawings: Fig. 1 a schematic representation of a laser processing device for eye surgery, Fig. 2 a schematic representation of the cornea of a patient, Fig. 3 and Fig. 4 a contact glass for the laser processing device of the Fig. 1, where Fig. 3 a top view and Fig. 4 is a sectional view, and Fig. 5 to 8 schematic sectional views of contact lenses similar to the Fig. 3 / 4.

[0023] Fig. 1 shows a treatment device for an ophthalmic surgical procedure similar to that described in EP 1159986 A1 or US 5549632. The treatment device 1 of Fig. 1 is used to perform a vision correction on a patient's eye 2 according to the known femtosecond LASIK procedure. For this purpose, the treatment device 1 has a laser 3 that emits pulsed laser radiation. The pulse duration is, for example, in the femtosecond range, and the laser radiation acts in the cornea by means of nonlinear optical effects in the manner described above. The treatment beam 4 emitted by the laser 3 along an optical axis A1 falls on a beam splitter 5, which directs the treatment beam 4 to a scanning device 6. The scanning device 6 has two scanning mirrors 7 and 8, which are rotatable about mutually orthogonal axes, such that the scanning device 6 deflects the treatment beam 4 two-dimensionally. An adjustable projection optics system 9 focuses the treatment beam 4 onto or into the eye 2. The projection optics system 9 has two lenses 10 and 11.The treatment device 1 represents a laser processing device.

[0024] A contact lens 12 acting as an adapter is arranged downstream of the lens 11 and is firmly connected to the lens 11 and thus to the beam path of the treatment device 1 via a holder H. The contact lens 12, which will be described in more detail below, rests against the cornea of the eye 2. The optical combination of the treatment device 1 with the attached contact lens 12 causes the treatment beam 4 to be bundled into a focus 13 located in the cornea of the eye 2.

[0025] The scanning device 6, as well as the laser 3 and the projection optics 9, are controlled by a control unit 14 via control lines (not further designated). The control unit 14 determines the position of the focus 13 both transversely to the optical axis A1 (through the scanning mirrors 7 and 8) and in the direction of the optical axis A1 (through the projection optics 9).

[0026] The control unit 14 further reads a detector 15, which reads radiation backscattered from the cornea, which passes through the beam splitter 5 as a return radiation 16. The operation of the laser 3 can be controlled very precisely using the detector 15.

[0027] The contact lens 12 ensures that the cornea of the eye 2 achieves the desired shape. Due to the contact of the cornea 17 with the contact lens 12, the eye 2 is in a predetermined position relative to the contact lens 12 and thus to the treatment device 1 connected to it.

[0028] This is shown schematically in Fig. 2, which shows a section through the cornea 17. In order to achieve exact positioning of the focus 13 in the cornea 17, the curvature of the cornea 17 must be taken into account. The cornea 17 has an actual shape 18 that varies from patient to patient. The adapter 12 now rests against the cornea 17 in such a way that it deforms it into a desired target shape 19. The exact course of the target shape 19 depends on the curvature of the front surface of the contact lens 12 facing the eye 2. The adapter 12 provides known geometric and optical conditions for introducing and focusing the treatment beam 4 into the cornea 17.Since the cornea 17 rests against the contact lens 12 and this in turn is fixed relative to the beam path of the treatment device 1 via the holder H, the focus 13 can be positioned exactly three-dimensionally in the cornea 17 by controlling the scanning device 6 and the adjustable projection optics 9.

[0029] The Fig. 3 and Fig. 4 show an embodiment of the contact glass 12 in detail; Fig. 4 is a sectional view, Fig. 3 a view of the contact glass 12 from the front (in Fig. 4 from below), i.e., within the patient's field of vision. The contact lens 12 is constructed in two parts and consists of a lens body 22, which is fastened in a frame 37, for example, glued at an adhesive point 43. The lens body is made of glass or a medically approved plastic, e.g., PMMA or polycarbonate. These materials can also be used for the frame, which can additionally be made of polyurethane or silicone rubber. By pressing the contact lens 12 onto the cornea 17, the front surface 29 of the lens body 22 held in the frame 37 gives the cornea 17 the desired shape 19.

[0030] To provide the negative pressure, the frame 37 has a nozzle 38, which has a Luer-Lock connection 39 and a negative pressure supply line 40 running within the nozzle. The supply line 40 opens laterally of the lens body 22 above a connecting ring 41 of the frame 37. Between an inner ring surface 46 of the connecting ring 41 facing the lens body 22 and the lens edge 47, which is frustoconical in this embodiment, an annular gap 44 is formed. This gap is connected to the supply line 40 and acts as a suction channel through which a negative pressure can be applied to the cornea in a ring shape. By means of negative pressure at the Luer-Lock connection 39, the contact lens 12 is thus attached to the eye in such a way that the cornea is pressed against the anterior surface 29 of the lens by mechanical pressure, thereby achieving the desired shape 19.

[0031] The attachment ring 41 protrudes relative to the optical axis A1 relative to the front surface 29 of the lens.

[0032] When the contact lens is placed on the cornea, contact is first established between the anterior surface of the lens 29 and the corneal vertex. As the cornea is further pressed against the anterior surface of the lens 29, contact with the cornea is established over an increasingly larger area of the anterior surface of the lens. When the cornea is completely in contact with the anterior surface of the lens 29, due to the curvature of the cornea becoming more pronounced in the peripheral region of the cornea, no contact is yet established between the axially foremost contour of the attachment ring 41 and the cornea, so that the suction channel provided by the annular gap 44 is not yet closed by the cornea. In this state, it is still possible to adjust the eye in contact with the anterior surface of the lens 29 so that the optical axis A1 is positioned exactly as desired, for example, coincides with the visual axis.Only when the contact lens and the eye are pressed further together does the cornea also adhere to the axially frontmost contour line 45 of the attachment ring 41, whereby the suction channel at the annular gap 44 is closed and the contact lens 12 is attached to the eye.

[0033] The frame 37 is thus designed with respect to the attachment ring 41 such that the axially frontmost contour line 45 of the attachment ring 41 does not protrude beyond a curved surface defined by the curvature of the eye when the cornea is fully pressed against the anterior lens surface 29. In one embodiment, the attachment ring 41 lies exactly in the imaginary extension of the curved surface. For simplification, reference can also be made to the curvature of the anterior lens surface 29.

[0034] The shape of the annular gap 44, which tapers at an acute angle from the eye, reliably prevents parts of the cornea from being sucked into the area of the supply line 40, thereby at least partially clogging or bloating it. Blockage of the suction channel 44 is also avoided, thus ensuring a circular application of the negative pressure.

[0035] The Fig. 5 to 8 schematically show different embodiments of the geometry of the lens body 22 and the mount 37. Elements that are already present in the design of the Fig. 3 / 4 are provided with the same reference symbols, so that in this regard, reference is also made to the description of the Fig. 3 and Fig. 4 is referred to.

[0036] The contact lens 12 again has the lens body 22, which is held in the mount 37. The lens body 22 is defined by an entrance surface 23 and the front lens surface 29. The preferred shape is a plano-concave lens, with the concave front lens surface 29 particularly preferably corresponding to the curvature of the human cornea or having a somewhat flatter curve. However, other shapes are also possible; in particular, the front lens surface 29 can also be aspherical to minimize optical aberrations.

[0037] The mount 37 encloses the lens body 22 over a portion of its circumference, thereby forming a connecting surface between the lens body 22 and the mount element 37 essentially along a cylindrical surface. The annular gap 44, which serves as a suction channel, is formed between the edge of the lens body 22 and the attachment ring 41 of the mount 37 and the edge 47 of the lens front surface 29 of the lens body 22.

[0038] To execute this annular gap, as the Fig. 5 to 8, either the inner ring surface 46 of the attachment ring 41 and / or the lens edge 47 can be conical, ie, can be inclined relative to the optical axis A1. In the embodiment of the Fig. 5, the lens edge 47 is conical, the inner ring surface 46 is cylindrical. Furthermore, it can be clearly seen that the attachment ring 41 does not protrude from the already mentioned curvature surface K, which determines the curvature of the cornea, but rather remains slightly behind. The design of the Fig. 5 has the advantage that a simple, essentially tubular mount 37 can be used. Furthermore, the diameter of the lens front surface 29 is smaller than that of the entrance surface 23.

[0039] The opposite case is shown by the Fig. 6, here the lens edge 47 is cylindrical, while the inner ring surface 46 is conical, with the cone now opening towards the curved surface K. Here, too, the attachment ring 41 extends exactly to the curved surface K.

[0040] In the construction according to Fig. 7, both the lens body 22 at the lens edge 47 (tapering toward the eye) and the inner ring surface 46 (expanding toward the eye) are conical. Furthermore, the axially foremost contour of the attachment ring 41 remains behind the curved surface K. This has the advantage that complete adjustment of the eye relative to the contact lens 12 is possible, and the suction channel is only closed by contact with the cornea when additional mechanical pressure is applied.

[0041] Fig. 8 finally shows a construction similar to the Fig.7, however, both the inner ring surface 46 and the lens edge 47 are tapered towards the eye. The smaller diameter of the contact surface of the contact lens 12 on the eye combined with the large diameter of the entrance surface 23 is advantageous in this case.

[0042] Of course, the geometric configurations described here can also be used advantageously individually or in other combinations not expressly shown or described.

Claims

[1] Method for attaching a contact lens (12) in ophthalmic surgery, wherein - a contact lens (12) is used which has a lens body (22) accommodated in a mount (37), which has a concave front lens surface (29) designed to be placed on the eye (2), wherein an annular gap (44) is formed at the edge of the front lens surface (29) between the lens body (22) and the mount (37), which, together with the applied eye (2), acts as a suction channel, via which negative pressure can be applied to attach the contact lens (12) to the eye (2), wherein the mount (37) is designed such that when the eye (2) is fully applied to the front lens surface (29) the suction channel between the annular gap (44) and the eye (2) is not yet closed, and - the contact lens (12) is brought close to the eye (2) in such a way that the front surface of the lens (29) initially only touches a central area of the cornea, - with increasing placement, the cornea gradually rests against the complete front surface of the lens (29), wherein in this state the suction channel is not yet closed and in this state an alignment of the contact glass (12) with respect to the eye (2) can be carried out, and after reaching a desired adjustment position the distance between the contact glass (12) and the eye (2) is reduced, whereby the annular gap (44) is closed by the cornea and the eye (2) is fixed with respect to the contact glass (12) by negative pressure. [2] Method according to claim 1, characterized by that the contact glass (12) is used in which the lens front surface (29) is concave according to a curved surface (K) and the axially foremost contour of the frame (37) towards the eye (2) lies in an imaginary extension of the curved surface (K) or at least does not protrude relative to it. [3] Method according to claim 2, characterized bythat the contact glass (12) is used in which an inner surface of the mount (37) delimiting the annular gap (44) and / or an edge surface (47) of the lens body (22) delimiting the annular gap (44) is designed as a truncated cone surface running obliquely to the optical axis (A1). [4] Method according to one of the above claims, characterized by that the contact lens (12) is used in which the annular gap (44) tapers away from the eye (2). [5] Method according to claim 4, characterized by that the contact glass (12) is used in which the end of the annular gap (44) facing away from the eye (2) converges at an angle ≤ 90°. [6] Method according to one of the above claims, characterized by that the contact lens (12) is used in which the front lens surface (29) is aspherical. [7] Method according to one of the above claims, characterized bythat the contact glass (12) is used in which a coding element coding a geometric or optical parameter of the contact glass (12) is provided. [8] Method according to claim 7, characterized by that the contact glass (12) is used in which the coding element is designed for color coding. [9] Method according to one of the above claims, characterized by that the contact lens (12) is used in which the front surface (29) of the lens is formed according to a curved surface (K) and the curved surface (K) is curved more flatly than the cornea of the eye.

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