US-12616609-B2 - Equipment and methods for refractive surgery, particularly for keratoplasty

US12616609B2US 12616609 B2US12616609 B2US 12616609B2US-12616609-B2

Abstract

Equipment and methods for refractive surgery, including for keratoplasty. The invention describes equipment and methods for the production and implantation of a lamella of a tissue or material for the purpose of correcting a corneal geometry at maximum precision that is thus improved in relation to the prior art. The invention facilitates restoration of normal corneal geometry together with optical functionality of the cornea which is improved in relation to the prior art. A planning device, a treatment system and a planning method are designed to couple a device coordinate systems of the laser devices involved and characterization devices by application of registration and to uniquely register the supplied measurement data for generating the lamella to be implanted to the device coordinate systems by a specific, defined edge geometry of a blank from which the lamella is produced, and by the lamella, and by additional system and method aids.

Inventors

Mark Bischoff
Robert Pomraenke

Assignees

CARL ZEISS MEDITEC AG

Dates

Publication Date: 20260505
Application Date: 20210326
Priority Date: 20200401

Claims (20)

1 . A treatment system for refractive surgery, including for keratoplasty, said treatment system comprising: a planning device that generates control data for the treatment system for the refractive surgery; a first laser device and at least one characterization device; a second laser device; wherein the first laser device, is configured to generate at least one incision within a corneal stroma of an eye and is controllable by operation of the control data to generate the at least one incision within the corneal stroma thereby to create at least one cut surface defining an intrastromal pocket in the stroma, the intrastromal pocket being bounded by the corneal stroma and having an anterior surface and a posterior surface and a perimeter within the corneal stroma; the planning device including a first interface that supplies first measurement data regarding parameters of the cornea to the characterization device, a second interface that supplies second measurement data or model data about a lamella which is insertable into the intrastromal pocket following the generation of the at least one cut surface wherein the second laser device is configured to process a blank to form the lamella and comprises a holder on which the blank is affixable during the treatment by the second laser device; wherein the planning device is furthermore configured to generate control data for the second laser device of the treatment system, to control the second laser to process the blank to form the lamella to be shaped in a patient-specific fashion, and wherein the planning device further comprises a fourth interface that transmits control data to the second laser device; wherein the first laser device, the second laser device and the characterization device each have an equipment coordinate system, and the first laser device, the second laser device and the characterization device are coupled or couplable with respect to one another by a registration of the equipment coordinate systems, and the supplied second measurement data or model data of the lamella are registrable with respect to the equipment coordinate systems; and wherein the planning device further generates control data that facilitates active cooling of the holder, active cooling of the blank in the holder itself or both.
2 . The treatment system as claimed in claim 1 , wherein the first laser device, comprises a femtosecond laser device.
3 . The treatment system as claimed in claim 1 , wherein the characterization device, comprises an OCT (optical coherence tomography) device.
4 . The treatment system as claimed in claim 1 , wherein second laser device of the treatment system, comprises an excimer laser device.
5 . The treatment system as claimed in claim 1 , wherein the planning device is further configured to generate control data to institute a temperature regime that maintains a temperature below a maximum temperature for processing the blank to form the lamella using the second laser device.
6 . The treatment system as claimed in claim 1 , wherein the planning device is further configured to determine a substantially ring-shaped transition zone at an edge of the lamella, within which an edge thickness gradually transitions to a patient-specific thickness profile, and furthermore wherein control data are generated such that there is no processing of the edge of the lamella by the second laser device.
7 . The treatment system as claimed in claim 1 , wherein the planning device is furthermore configured to generate control data for the first laser device or a third laser device, an equipment coordinate system of which is likewise coupled to the aforementioned equipment coordinate systems by application of a registration, to generate or pre-process the blank, wherein the blank is able to be generated from a natural donor cornea or from artificial tissue, or the blank is pre-processable therein, by generating one or more cut surfaces in the donor cornea or the artificial tissue by operation of the first laser device or the third laser device.
8 . The treatment system as claimed in claim 7 , wherein the third laser device, comprises a further femtosecond laser device.
9 . The treatment system as claimed in claim 7 , wherein the planning device is further configured to define the one or more cut surfaces in the donor cornea or in the artificial tissue in such a way as to generate control data and transmit the control data to the first laser device or the third laser device with which a blank is generatable, the blank being defined by a correction zone situated in a center of the blank, a transition zone arranged around said correction zone and an edge zone arranged around said transition zone, the edge zone being provided for the subsequent separation prior to an insertion of the lamella into the cornea of the eye, and wherein the blank can be removed and affixed on a holder for purposes of processing with the second laser device.
10 . The treatment system as claimed in claim 9 , wherein the planning device is configured to define a position of calibration marks in the transition zone and/or edge zone and to generate control data for the first laser device or the third laser device, by application of which control data these calibration marks are able to be introduced during processing with the first laser device or the third laser device, wherein the calibration marks are defined such that they are usable as a single or multiple orientation feature during a processing of the blank by operation of the second laser device.
11 . The treatment system as claimed in claim 7 , wherein the planning device is configured to define the one or more cut surfaces in the donor cornea or the artificial tissue in such a way as to generate control data and transmit the control data to the first laser device or the third laser device with which a blank is generatable, the blank being defined by a correction zone situated in the center of the blank and a transition zone arranged around said correction zone, and this blank is further processable by the second laser device in the original donor cornea or in the artificial tissue.
12 . The treatment system as claimed in claim 11 , wherein the planning device is further configured to define the one or more cut surfaces in the donor cornea or the artificial tissue in such a way as to generate control data and transmit the control data to the first laser device or the third laser device with which a blank is generatable, the blank further having an edge zone which is arranged around the transition zone and which is provided for subsequent separation prior to an insertion of the lamella into the cornea of the eye.
13 . The treatment system as claimed in claim 12 , wherein the planning device is configured to define a processing profile of a correction zone for the second laser device and determine the control data in such a way that the processing profile of the correction zone situated in a center of the blank and of the transition zone arranged around said correction zone is generatable by operation of the second laser device and an excavation is generatable in the edge zone arranged around the transition zone, thereby facilitating removal of a lamella carved out of the donor cornea or the artificial tissue, or thereby facilitating further processing of the blank on a holder, in such a way that the holder cannot be hit by a processing laser beam of the second laser device.
14 . The treatment system as claimed in claim 11 , wherein the planning device is configured to define a position of calibration marks in the transition zone and/or edge zone and to generate control data for the first laser device or the third laser device, by application of which control data these calibration marks are able to be introduced during processing with the first laser device or the third laser device, wherein the calibration marks are defined such that they are usable as a single or multiple orientation feature during a processing of the blank by operation of the second laser device.
15 . The treatment system as claimed in claim 14 , wherein the planning device is further configured to define calibration marks which are arranged multiple times above one another and/or offset from one another and/or at different levels in the blank to be processed by the second laser device.
16 . The treatment system as claimed in claim 1 , wherein the planning device is configured to generate the control data taking into account a defined initial hydration state of the blank or of the lamella ex vivo, and a change in the hydration state of the lamella during or after the implementation.
17 . The treatment system as claimed in claim 16 , wherein the planning device is configured to generate the control data taking into account the defined initial hydration state of the blank or of the lamella ex vivo, and the change in the hydration state of the lamella during or after the implementation, by application of a constant expansion factor.
18 . The treatment system as claimed in claim 1 , wherein the planning device further generates control data that facilitates active cooling of the holder, the blank or both such that a temperature of the blank can be lowered in such a way that the blank is processed in a frozen state or wherein the planning device further generates control data that facilitates active cooling of the holder, the blank or both such that the temperature is lowered to a dewpoint of air in an airstream so that constant humidity is maintained thereby balancing condensation and evaporation of the blank.
19 . The treatment system as claimed in claim 1 , further comprising a temperature control device which comprises at least one of the following configurations: active electrical cooling by application of a Peltier element; active cooling by application of an introduced coolant; active cooling by an air flow; passive cooling by pre-cooling the holder with or without the blank affixed thereon; and a chamber, separated from surroundings, for processing the blank.
20 . The treatment system as claimed in claim 1 , further comprising a temperature sensor that monitors the temperature of the blank and/or of the holder during the processing.

Description

RELATED APPLICATIONS This application is a National Phase entry of PCT Application No. PCT/EP2021/058022 filed Mar. 26, 2021, which application claims the benefit of priority to DE Application No. 10 2020 204 261.6, filed Apr. 1, 2020, the entire disclosures of which are incorporated herein by reference. TECHNICAL FIELD The present invention relates to apparatuses and methods of refractive surgery, in particular for keratoplasty, for example sutureless intrastromal anterior lamellar keratoplasty (sIALK). BACKGROUND Apparatuses and methods of refractive surgery, in particular for keratoplasty, for example as described in DE 10 2007 019 815 A1 and WO 2008/131888 A1, have previously assumed that a piece of tissue is always taken from the recipient's eye during the treatment. To this end, the sIALK method has hitherto been described in such a way that there always has to be a resection because only this creates a depression in the stromal bed (vacancy) which simplifies an implementation of an implant or transplant in the correct position. A vacancy has inherent disadvantages, for example the burden of surgery connected to the generation and the loss of tissue. However, the advantages often dominate: obtaining biopsy material and simplified positioning of the implant. In a certain configuration, there is also an improvement in the uncorrected visual acuity (UDVA) in addition to an improvement in the corrected visual acuity (CDVA). Thus, the visual acuity is corrected at the same time. In parts, this idea has also already been formulated in DE 10 2007 019 815 A1 or WO 2008/131888 A1. Shaping can be implemented in different ways within the scope of the production of the implant, more particularly a tissue implant. One possible procedure consists of impressing the target geometry on an implant blank by application of laser processing. For refractive surgery, in particular, this is a procedure of interest because the refractive laser systems conventional there can be adapted to such methods with little outlay. Consequently, the patient-specific adaptation of the implant could be carried out by the medical user in the clinic and would not have to be implemented in a tissue bank or elsewhere. Thus, such an approach would have logistical advantages and would also reduce some risks to the patients. However, the required processing accuracy cannot be reliably obtained in the case of a simple transfer of a PRK or LASIK treatment procedure to the problem of the implant production. This is down to the fact that in contrast to the usual use when shaping stromal corneal tissue for the subtractive correction of a refractive error, in which tissue layers up to approximately 13 μm thick are removed per diopter correction and hence there hardly ever is a maximum removal of more than 100 μm, a removal of more than 100 μm layer thickness is not unusual during the implant production. To ultimately obtain an absolute accuracy of the order of micrometers when removing so much is more difficult than to obtain the high relative requirement in terms of accuracy during a PRK correction, especially since the properties of the implant material may be subject to greater variations than is the case for stromal tissue during a PRK or LASIK treatment. Particularly high accuracy is required when shaping the implant within the correction zone of the tissue, which may be a natural donor corneal tissue or an artificial tissue with identical properties to natural corneal tissue, and for the geometry of the edge of said implant. Accurate fitting into an available vacancy in the tissue is often required for the periphery of the implant, which is referred to as an edge. (An accuracy of at least 10 μm, and 5 μm or less where possible, should be obtained in this case. In the ideal case, fitting can be implemented with 1 μm accuracy.) One aspect of this problem consists of the fact that the surgeon may not damage the edge of the implant during the entire process, for example when separating the tissue to be transplanted from the surrounding tissue of the donor eye or when separating unneeded parts from the material. Naturally, these process steps require manual microsurgical work using surgical instruments. SUMMARY OF THE INVENTION Example embodiments of the invention include apparatuses and methods for producing and implanting a lamella of a tissue or material for the purposes of correcting a corneal geometry with the greatest precision, and hence with a better precision than in the prior art. In particular, embodiments of the invention assist in restoring a normal corneal geometry with a better optical function of the cornea than in the prior art. The invention includes various measures or features which all serve the purpose of improving the aforementioned apparatuses and methods of refractive surgery, in particular for keratoplasty, and which are ultimately used to achieve the production and implantation of a tissue or material for the purposes of cor