EP2004093A1

EP2004093A1 - Support element for compensating for deformations of the cornea of an eye

Info

Publication number: EP2004093A1
Application number: EP07727535A
Authority: EP
Inventors: Mark Tomalla; Gebhard Tomalla
Original assignee: Acritec AG; Tomalla Jutta
Current assignee: TOMALLA, JUTTA
Priority date: 2006-03-30
Filing date: 2007-03-29
Publication date: 2008-12-24
Also published as: KR20090052834A; US20100286770A1; WO2007113225A1

Abstract

The invention relates to a support element for compensating for deformations of the cornea (H) of an eye, with a one-part or multi-part annular support body (2) with which it is possible to compensate for keratoconus with minimal loading of the cornea of the treated eye. According to the invention, this is achieved by the fact that the support body (2) has a cross section that is flattened on one side and is otherwise rounded, such that a peripheral flattening (6) is formed on it.

Description

STUTZELEMENT TO THE COMPENSATION OF DEFORMATION OF THE HORNHAUT

AN EYE

The invention relates to a support element for compensating deformations of the cornea of an eye, which has a transverse slotted annular support body. Such support elements, here also referred to as support rings, are inserted into a channel which is introduced into the cornea of a human or animal eye and generally runs parallel to its contour in order to eliminate local, sight-limiting bulges of the cornea.

Such bulges are also referred to in the jargon as "keratoconus." They result from a progressive thinning and subsequent conical deformation of the cornea of the eye.

It is known that the corneal deformations arched outwards in keratoconus patients can be compensated by the formation of raised bulges, ie towards the interior of the eye. These bulges are generated by the introduction of displacement bodies, so-called "Intacs", in the proximal, ie pointing to the body, half of the cornea as possible outside of the visual field or in its edge zone. The known Intacs used as support elements are usually formed annularly with a round or hexagonal cross-section and produce after implantation in the cornea a torus. Due to the formation of beads, transversal tensile forces are generated in the cornea. These can be adjusted by an appropriate design of the socket element itself and the channel so that the diseased corneal tubercle (keratoconus) is compensated in accordance with the normal corneal vaulting.

In order to be able to easily introduce them into the channel formed in the cornea, the known support elements are usually composed of two half-rings. Such a ring is described, for example, in EP 0 732 891 B1. In the finished implanted state, this ring has a plate-horse-like shape with conically-projecting end abutment surfaces. About in the implanted state of these close to the inner surfaces of the molded channel in the cornea surfaces, the ring exerts tensile forces on the circumference of the ring surrounding the cornea section through which the relevant corneal section is stretched and thus smoothed.

Due to practical experience with support elements of the type described above, there is a desire for a support element, which makes it possible to compensate for keratoconus with minimized stress on the cornea of the treated eye.

This object is achieved according to the invention by a trained according to claim 1 support element. Advantageous embodiments of this support element are specified in the dependent of claim 1 claims.

With the invention, a support element for compensating for deformations of the cornea of an eye is available, which has a one-piece or multi-part annular support body in a conventional manner. According to the invention, this support body has a cross-section which is flattened on one side. This flattening is arranged according to the invention so that a peripheral end flattening is formed on the support element according to the invention. In the implanted state, this flattening forms a contact surface, with which the support element according to the invention bears tightly against the outwardly directed inner wall of the slot-like channel, which has been previously formed, for example by means of a laser beam, into the cornea of the respective treated eye. Outside its flattened portion of the cross section of the support element according to the invention is rounded. In this way, it is ensured that the forces exerted by a support element according to the invention are gently introduced into the sections of the cornea surrounding the support element and local load peaks are avoided.

An inventive support element is thus shaped so that the given in the prior art adverse influence on the corneal inner wall by bending and strain stress is minimized. A designed according to the invention support element is therefore predestined for implantation in a by means of a very high-frequency laser, z. As a femto-second laser, introduced into the cornea of the treated eye slit-like, parallel to Corneal contour and thus in a first approximation conical circular channel whose shape is similar to a divider spring.

The orientation of the flattening present on a support element according to the invention is preferably to be selected such that it is adapted to the orientation of the inner surface of the channel slot molded into the cornea in the implanted state. The advantages of the embodiment of the flattening acting as a support surface in the implanted state, which is adapted to the pitch angle of the contact surface of the channel, lie in the low surface pressure and thus low indentation behavior in the cornea in the region of the flattening.

The existing in a support member according to the invention flattening can therefore be designed so that the forces transmitted through them is optimally adapted to the locally given their implantation in their respective neighborhood conditions. In cases where the geometry and the nature of the corneal portion into which the support element is to be used is uniform, the flattening formed on the support element may form a conically tapered annular disc surface. Such a shaped support element can be produced particularly easily and inserted precisely into the channel slot molded into the cornea to be treated.

In addition, a conically shaped flattening results in a relatively large current range relative to the thickness of the cornea for the implantation of the cornea Stutzringes can be selected. A nearly horizontal, ie approximately parallel to the circular plane of the support element extending flattening is preferably limited to the proximal half of the cornea, in order to avoid or exclude the consequences of a Durchdruckens the Stutzringes outward.

An essential advantage of a support element according to the invention consists in the high centering effect which is achieved on account of its conically shaped flattening in the described cornea channel.

In order to be able to effect a large functional area with the preferably large support surface, the angular position (flattening angle) of the flattening acting as a support surface between about 25 to above the horizontal, in this case 0 °, goes out. By aligning the flattening the thrust can be adjusted, which is initiated in the implanted state of the socket element in the surrounding cornea. Depending on the geometry and position of the channel introduced into the cornea, load peaks can be avoided by the flattening angle being> 0 °.

Due to the fact that in a horizontal orientation, the flattening does not run parallel to the channel wall produced in the curved cornea, but at an angle to this, the horizontal flattening exerts a thrust component on the outwardly over the frontal area of the cornea.

The greatest security in the predictions of the outcome of the operation and thus also in the determination The dimensions to be selected of a support element according to the invention can be achieved with slot channels introduced into the proximal region of the cornea. In this arrangement of the channel to be introduced for the implantation of a support element according to the invention results in a large thickness of the outer with respect to the channel slot area of the cornea in comparison to the thickness of the interior relative to the channel slot area of the cornea.

In order to bring about a uniform introduction of the forces introduced into the cornea by a support element according to the invention and an equally uniform compensation of the corneal convexity to be treated, the support body of a support element according to the invention should have a circumferential angle of at least 350 °, in particular up to 360 °.

A support element according to the invention offers numerous possibilities for variation, regardless of the particular orientation of the flattening acting as a support surface, while retaining its basic shape according to the invention. Thus, even by a parallel displacement of the flattening in the radial cross-sectional direction while maintaining the diameter of the support body, the volumes occupied by the support element change.

In order to reinforce the extent of peripheral recovery of the cornea at certain points and to reduce it at other locations, it is also possible, seen on the ring circumference of a support element according to the invention, local reductions or extensions of the ring cross-section, in cross-sectional radial Direction of the height or in ringradialer direction the width concerning and here make both the outer or inner diameter or even one of both or both both concerning.

Accordingly, the local conditions of the cornea or the forces to be applied locally in the design of a support element according to the invention can be taken into account by varying the thickness of the support body along its circumference. For this purpose, the thickness of the support body may be varied in the direction of its height measured perpendicular to the circle plane. Alternatively or additionally, it is furthermore possible for the same purpose to vary the width of the support body measured parallel to the circle plane. It is of course not necessary that the respective variation symmetrical to

Cross-sectional center is carried out, but it can also be asymmetric indentations or bulges formed on the support element, if this is necessary in view of the desired effect in the implanted state of the support element according to the invention. This available with the invention

The possibility of design can be decisive, above all, in the correction of eccentric keratoconus formation lying eccentrically to the support element.

A particularly gentle embodiment of the invention surrounding the environment of the support element according to the invention is characterized in that the edge of the cross section of the support body extends in a circular arc outside the area of the flattening. In principle, it is conceivable convex or concave on or flattening the flattening formed on a support member according to the invention, frontally encircling and in the implanted state serving as a support surface while maintaining their basic conical to horizontal orientation, if this in terms of each desired effect as expediently turns out. However, taking into account the fact that the wall of the channel formed into the cornea in the implanted state will usually be flat, it is favorable if the flattening itself is also flat. Accordingly, a further advantageous variant of the invention provides that the edge of the cross section of the Stutzkorpers runs in a straight line in the region of its flattening.

In order to avoid that in the implanted state, the areas of the cornea adjacent to the edges of the support element are excessively stressed, the transition between the flattening and the adjoining area of the support body should be rounded.

The handling of a support element according to the invention during insertion into the slot channel previously molded into the eye can be simplified by forming a flattened step on at least one end of its support body. This paragraph can serve as a point of attack for the tool used by the surgeon. In order to facilitate a secure coupling of tool and Stutzkorper, an opening can be formed in the flattened paragraph. The risk of injury to the cornea can be minimized by the fact that in the area of the transition between the flattened paragraph and the support body is formed a slope.

A support element according to the invention can be produced from commercially available, well biocompatible plastics from which the already known "intacs" are made use, the support body are composed of more than one part.So it is also possible with a support element according to the invention to assemble the support body, for example, two half-rings.

The invention will be explained in more detail with reference to an exemplary embodiments illustrative drawing. Each show schematically:

Figure 1 is a support element in plan view.

FIG. 2 shows the support element in a section along the section line X-X drawn in FIG. 1; FIG.

FIG. 3 shows an end section of the support element in an enlarged view corresponding to FIG. 1; FIG.

4 shows the end section in a section along the ring axis of the support element;

FIG. 5 shows the support element in a section along the section line YY drawn in FIG. 4; FIG. 6 shows a section of a cornea of an eye with the support element implanted therein in a sectional view;

Fig. 7 is a varied support member in one of Fig. 5 corresponding sectional view.

The support element 1 shown in FIG. 1 comprises an annular body 2 which surrounds an angular range of more than 350 ° and is composed of two semi-tubular body halves 2a, 2b and on whose end portions a flattened shoulder 3,4 is formed.

The Stutzkorper 2 has a cross-section whose basic shape corresponds to the shape of a circle, but which is obliquely flattened in the region 5 of its the one end face Sl of the support member 1 associated side. In this case, the edge R of the cross-section in its flattened region on a straight-line course, while he proceeds arc-shaped otherwise. In this way, a flat flattening 6 is formed on the one end face Sl of the Stutzkorpers 2, which circulates on the one hand to the Stutzkorper 2 and on the other in the direction of the central axis M of the support member 1 tapered at an angle OC relative to the circular plane E of the overall annular Support element 1 is inclined. The transitions 7,8 between the flattening 6 and the adjacent sections of the Stutzkorpers 2 are formed rounded.

As a result of the positioning of the flattened region 5 of the cross-section of the support body 2, it can be easily understood from the comparison of FIGS. 5 and 7 Variants can be seen, in otherwise unchanged geometry in a simple manner, the volume of the Stutzkorpers 2 can be adjusted.

The flattening 6 is guided over the free ends of the Stutzkorpers 2 also up to the free end of the molded on the Stutzkorper 2 flattened paragraphs 3,4. The heels 3,4 have a thickness which is about half as large as the thickness of the Stutzkorpers 2. When importing the neck element 1 in an incised into the cornea H of the eye to be treated K channel paragraphs 3.4 are used, by means of a suitable, not shown here tool to hold the support element 1 and push into the channel K. In order to ensure a secure hold, in each case a perpendicular to the flattening 6 aligned and this piercing Durchgangsoffnung 9,10 is formed in the paragraphs 3,4.

To reduce the risk of accidental injury to a minimum when importing the neck element 1 into the channel K, the area of the transition U of the heel 3,4 to the neck body 2 is in each case beveled at an angle β of 45-60 °.

In order to treat a keratoconus C (not shown here) on an eye which is likewise not further illustrated here, the slot-shaped channel K is cut into the cornea H by means of a femtosecond laser known per se in a manner which is also known per se. The walls Wa, Wi delimiting this channel K run essentially parallel to the curved surface Oa of the cornea H. The channel K is thereby positioned such that the thickness Da of the cornea H between it and the external surface Oa of the cornea H remaining corneal area Ba is greater than the thickness of the proximal, remaining between it and the inner surface Oi of the cornea H area Bi.

Subsequently, first the first support body half 2a and then the second support body half 2b of the support member 1 is pushed into the channel K. The support body halves 2 a, 2 b forming together the support body 2 of the support element 1 are each aligned so that the flattening 6 abuts the outer wall Wa associated with the surface Oa of the cornea H.

Due to its flat, conically oriented shape, the flattening 6 is close to the wall Wa, without deforming them to a greater extent. At the same time, however, the proximal region Bi of the cornea H is displaced from the curved region of the support element 1 in the direction of the interior I of the eye, so that outwardly directed tensile forces Z arise in this region in the radial direction of the eye. These cause the area of the cornea H in which the keratoconus C originated to be drawn towards the interior I of the eye until the curvature of the cornea H, also in the area of the keratoconus C, returns to the general curvature of the healthy area of the cornea H is adjusted.

It should be noted that the free space K 'remaining in the channel K in FIG. 6 at the side of the support element 1 or its respective support body 2 is shown exaggerated for clarity. In practice, the width of the channel K will of course be adapted to the width of the support member 1 and its support body 2, that after implantation as low as possible Free space K 'remains laterally of the support element 1 or its support body 2.

The embodiment of the invention described above in detail is to be understood only as an example.

The selected basic design of the support element according to the invention enables a simple, low-resistance implantation and, because of its generally rounded shape, involves a very low risk of injury to the cornea. Of course, this does not exclude that - apart from the flattening which is always to be provided according to the invention - the cross-section of a support element according to the invention may also have cross-sectional shapes other than those expressly mentioned here,

Advantageously, the inwardly-lying cross-sectional shape of a support element according to the invention is always designed so that the adverse effect on the corneal inner wall is kept as low as possible by bending and expansion stresses.

It is also conceivable that in order to simplify the implantation process, instead of the shoulders formed on the ends of the support body, a bore or a comparable opening is provided, to which an implantation instrument can be attached.

The high stability and reliability of the surgical results is also helped by the precision of the canal design with the femtosecond laser. This precision relates to both the location of the canal in terms of corneal thickness and canal history Aquidistante to the corneal contour. Such a slot channel means that each part, the distal (outer) and the proximal (body facing) portion, has a uniform thickness for itself.

When implanting the neck element according to the invention with its flattening in the cornea, which has a conical surface serving as the surface of the stump, the channel wall facing outwards offers an advantageous abutment and counterpart surface for the flattening of the neck element. Due to the large-scale support creates a clearly geometrically definable abutment for the forces that result from the tensioning of the thinner inner cornea layer on the advantageously rounded inward and perpendicular to the corneal contour built-ring ring.

The extent of the corneal deformation is determined by the size and shape of the cross-sectional area of the support element in addition to the position diameters of the channel and support element.

REFERENCE NUMBERS

1 support element

2 tubes

2a, 2b Stutzkorperhalften

3.4 paragraph

5 flattened area of the cross section of the Stutzkorpers. 2

6 level flattening

7.8 transitions between the flattening 6 and the adjacent sections of the Stutzkorpers 2

9.10 passage openings

CC angle

Ba, Bi corneal areas ß angle

C Keratoconus

E Circular plane of the support element 1

H cornea of the eye to be treated

I inside of the eye

K in the cornea H cut channel

K 'free space

M center axis of the support element 1

Oa, Oi surfaces of the cornea H

R edge of the cross section

Sl first end face of the Stutzkorpers. 2

Wa, Wi the channel K delimiting walls

Z tensile forces

Claims

PATENT APPLICATIONS

1. support element to compensate for deformations of the cornea (H) of an eye, with a one or more parts annular Stutzkorper (2), characterized in that the Stutzkorper (2) has a flattened on one side and otherwise rounded cross section, so that at him a circumferential end flattening (6) is formed.

2. Support element according to claim 1, characterized in that the flattening (6) forms a conically tapered annular disk surface.

3. Support element according to one of the preceding claims, d a d u r c h e c e n e c i n e t, d a s s

Flattening (6) at a flattening angle (CC) of 0 ° to 25 ° relative to the circular plane (E) of the support element (1) is inclined.

4. support element according to claim 3, characterized in that the Abf laughter angle (CC)> 0 °. - 2 -

5. Supporting element according to one of the preceding claims, characterized in that the supporting body (2) comprises a circumferential angle (β) of at least 350 °.

6. Supporting element according to one of the preceding claims, characterized in that the thickness of the supporting body (2) is varied along its circumference.

7. The support element according to claim 6, wherein the thickness of the support body is varied in the direction of its height measured perpendicular to the circle plane (E).

8. The support element according to claim 6, wherein the width of the support body (2) measured parallel to the circle plane (E) is varied.

9. Supporting element according to one of the preceding claims, characterized in that the edge (R) of the cross section of the supporting body (2) runs in a circular arc outside the region (5) of the flattening.

10. Supporting element according to one of the preceding claims, characterized - 3 -

The edge of the cross-section of the support body (2) runs rectilinearly in the region (5) of its flattening.

11. Restorber element according to one of the preceding claims, characterized in that the transition between the flattening (6) and the adjacent region of the support body (2) is rounded off.

12. Supporting element according to one of the preceding claims, wherein a flattened shoulder (3, 4) is integrally formed on at least one end of the support body (2).

13. A support element according to claim 12, wherein a recess is formed in the flattened shoulder (3, 4).

14. Resting element according to one of claims 12 or 13, wherein a skew is formed in the region of the transition between the flattened shoulder (3, 4) and the supporting body (2).

15. support element according to one of the preceding claims, d a d u r c h e c e n e c e s e s, e e s of the Stutzkorper (2) is integrally formed.