Centering device for determining the centering of a visual axis of an eye

Abstract

Centering device (12) for determining the centering of a visual axis of an eye (14) to a beam path, wherein the centering device (12) comprises at least two color sources (16, 18), a control unit (20), and a detection unit (22), wherein the color sources (16, 18) are arranged in the beam path of the centering device (12), wherein a respective color signal (17, 19) in a visible spectral range can be output via the beam path to an eye interface (26) by the color sources (16, 18), wherein the wavelength of the respective color signals (17, 19) differs, and wherein the control unit (20) is configured to control the detection unit (22) for determining an eye alignment when a superposition criterion is present, indicating a superposition of the color signals (17, 19) on the visual axis, wherein the detection unit (22) is trained to do soto determine the eye alignment by means of an image of the eye (14) and by identifying landmarks in the image, in particular a pupil center and / or characteristics of the iris.

Description

[0001] The invention relates to a centering device for determining the centering of a visual axis of an eye relative to a beam path, and to a treatment device comprising at least one ophthalmic laser and such a centering device. Furthermore, the invention relates to a method for determining the centering of a visual axis of an eye, a computer program for implementing the method, and a computer-readable medium on which the computer program is stored.

[0002] In ophthalmology therapy and diagnostic systems, one challenge is to center an eye, particularly its visual axis, for treatment and / or diagnosis. The visual axis represents the field of view of the eye's sharpest vision, and a treatment or diagnosis shifted relative to the visual axis can lead to undesirable results. Finding the correct centering of the eye based on the visual axis is difficult and time-consuming.

[0003] Therefore, it is an object of the invention to improve the centering of a visual axis of an eye.

[0004] This object is achieved by the independent patent claims. Advantageous developments of the invention are disclosed in the dependent patent claims, the following description, and the figures.

[0005] The invention is based on the idea that chromatic aberration is always present in the human eye, and thus different wavelengths that fall off-center on the eye are focused with varying strengths in the eye. This creates a transverse aberration in the eye that can be used for centering. The idea is that two sources with different wavelengths are arranged coaxially in a beam path, with the visual axis centered to the beam path when both wavelengths coincide in the retina.

[0006] The invention provides a centering device for determining a centering of a visual axis of an eye with respect to a beam path, wherein the centering device has at least two color sources, a control device and a detection device, wherein the color sources are arranged in the beam path of the centering device, wherein a respective color signal in a visible spectral range can be output by the color sources via the beam path to an eye interface, wherein a wavelength of the respective color signals differs, and wherein the control device is designed to control the detection device to determine an eye alignment if an overlay criterion is present which indicates a superposition of the color signals on the visual axis.

[0007] In other words, two different color signals are provided which are transmitted together in a beam path of the centering device and can be output at an eye interface. An eye interface here means an exit or window of the centering device to which an eye can be placed for examination and / or treatment. The eye interface is therefore an interface between the centering device and the eye, which can, for example, have a contact element against which the eye can be pressed. The color signals, which can be provided by color sources of the centering device, can enter the eye through the eye interface. The color signals only overlap at a position on the retina if this position lies on the visual axis of the eye.

[0008] If this overlap is detected, the alignment of the eye is determined using a detection device. The detection device can, for example, comprise a camera that can capture an image of the eye when the color signals are overlapped on the visual axis, since the visual axis is collinear with the beam path of the centering device when the color signals are overlapped. Otherwise, the color signals are displaced due to chromatic aberration.

[0009] The color sources may comprise passive color sources, for example color dots or color plates, which can preferably be illuminated with a light source, or active color sources which generate a respective color signal, for example light sources, in particular laser light sources and / or color diodes.

[0010] Eye alignment can be determined, for example, by taking an image of the eye and determining landmarks, such as a pupil center, a corneal vertex, Purkinje images, or iris characteristics, in relation to the beam path of the centering device. The determined eye alignment with a centered visual axis can be in the form of data that can be transmitted to a diagnostic device and / or a treatment device. This means that the centering device can be used for therapeutic devices, such as ophthalmic lasers, or diagnostic devices, for example, for fitting glasses or contact lenses.

[0011] The superposition criterion, which indicates the superposition of the color signals on the visual axis, can be a rule or condition that is checked to determine whether the color signals are superimposed or not. For example, the superposition criterion can be met when the color signals spatially overlap on a retina, which can be determined optically, for example, particularly by an ophthalmoscopy device. Alternatively or additionally, an input device can be provided that a user or patient can use to input information if the color signals overlap in a perception.

[0012] The invention offers the advantage that centering of the eye can be improved and, in particular, performed more quickly. This allows for improved diagnostic and / or treatment results.

[0013] The invention also includes further developments which result in additional advantages.

[0014] A further development provides for the color sources to be designed as white light sources with respective color filters. This means that the color filters filter out specific wavelengths from the white light source and can thus provide a different color signal for each one.

[0015] A further development provides for the color sources to be configured as light-emitting diodes and / or lasers. In this case, collimated color signals can be emitted by the respective color sources, which makes it easier to detect overlapping color sources.

[0016] A further development provides that the wavelengths of the color signals are located at different ends of the visual spectral range, in particular one color signal in a red or orange spectral range and the other color signal in a blue or green spectral range. This means that the color signals located in the visible or visual spectral range can differ in that one color signal has a wavelength located at a lower end of the spectral range, for example, red or orange, and the wavelength of the other color signal can be located at the upper end of the spectral range, for example, blue or green. This can provide suitable color differentiation and / or an enhanced effect of chromatic aberration, which can increase the accuracy of determining centering.

[0017] Preferably, one of the color signals has a wavelength in the visible spectral range below 500 nanometers and / or the further color signal has a wavelength in the visual spectral range above 600 nanometers.

[0018] In a further advantageous development, the wavelengths of the color signals are spaced at least 200 nanometers apart. This means that at least a wavelength difference of 200 nanometers is provided between the color signals.

[0019] A further development provides that the detection device is additionally designed to determine an overlay of the color signals on a retina, wherein the overlay criterion is present when the overlay is determined. In other words, the detection device can, for example, in addition to a camera for detecting the eye alignment, also have an ophthalmoscopy device by means of which a projection of the color signals on the retina can be detected. If it is determined in such images that the color signals on the retina are superimposed, it can be concluded that the visual axis of the eye is coaxial with the beam path of the centering device. The overlay criterion can thus be present and the associated eye alignment can be determined. This development results in the advantage that an objective determination of the overlay can be provided.

[0020] A further development provides that the detection device is additionally designed to determine an overlay of Purkinje images of the color signals, wherein the overlay criterion is met upon detection of the overlay. Purkinje images refer to reflections of the incoming color signals by optical interfaces of the eye, wherein four different Purkinje images can arise from four interfaces. One can arise on the surface of the cornea, one on the posterior surface of the cornea, one on the anterior surface of the eye lens, and one on the posterior surface of the eye lens. To determine the overlay, in particular the first Purkinje image and the fourth Purkinje image of the respective color signals can be superimposed in order to determine the centration of the eye.In particular, not all Purkinje images of all color signals need to overlap at a single point; rather, those of the first color signal overlap at a first point, and those of the second color signal overlap at a second point. This allows for a further objective determination of the eye's centration.

[0021] A further development provides that the detection device is designed to determine the eye alignment by means of an image of the eye and a determination of landmarks in the image, in particular a pupil center and / or characteristics of the iris (iris). The landmarks can preferably be detected in relation to the beam path of the centering device. This means that characteristic points of the eye or landmarks can be determined via an image of the eye in order to determine the position and / or orientation of the eye that exists when the color signals are superimposed. These landmarks can then be used, in particular, in further steps, for example during a treatment of the eye, to detect the centering or the visual axis.

[0022] A further development provides that the centering device has an input device configured to generate a control signal for the control unit, wherein the superimposition criterion is provided by the generated control signal. In other words, the patient can use the input device, which may comprise, for example, a pushbutton or a key, to inform the centering device when they perceive the color signals superimposed and thus manually trigger the superimposition criterion. This eliminates the need for additional detection devices, which reduces complexity and / or costs.

[0023] A further aspect of the invention relates to a treatment device comprising at least one ophthalmic laser for separating a corneal volume of a human or animal eye by means of optical disruption, in particular by means of photodisruption and / or ablation, and / or for a laser-induced structural change, in particular a laser-induced refractive index change and / or laser-induced cross-linking, and the aforementioned centering device. Preferably, the beam path of the centering device and the beam path of the laser can be coaxial. The eye interface or patient interface of the centering device can also be the same as that for the treatment device, wherein the eye interface can preferably have a contact element for contacting the eye on the treatment device or centering device.The respective laser can be designed to at least partially separate a predefined corneal volume with predefined boundary surfaces of a human or animal eye by means of optical breakthrough, in particular to at least partially separate it by means of photodisruption and / or to ablate corneal layers by means of (photo)ablation and / or to cause a laser-induced refractive index change in the cornea and / or the eye lens.

[0024] In a further development of the treatment device, it is provided that the eye interface has a fixation device for the eye, in particular a suction ring, wherein the control device is designed to control the fixation device for fixating the eye when the superimposition criterion is met. This means that the eye can be fixed in the position in which the color signals lie one above the other on the visual axis by the fixation device fixing the eye. For this purpose, the fixation device can be designed, for example, as a suction ring that generates a negative pressure and thus holds the eye in position. Alternatively, the detection device can also check when the eye alignment matches the determined eye alignment when the color signals are superimposed, in which case the fixation device can be controlled to fix the eye.

[0025] A further aspect of the invention relates to a method for determining a centration of a visual axis of an eye, using the centration device described above, wherein at least two color sources generate a respective color signal in a visible spectral range and with different wavelengths and output it to an eye interface via an at least partially common beam path, wherein a control device checks for the presence of an overlay criterion by which an overlay of the color signals on a visual axis of an eye located at the eye interface is indicated, wherein a detection device determines an eye alignment if the overlay criterion is present. This results in the same advantages and variation options as with the centration device.The respective method may include at least one additional step that is executed precisely when a use case or application situation occurs that has not been explicitly described here. This step may, for example, include outputting an error message and / or a request for user feedback. Additionally or alternatively, it may be provided that a default setting and / or a predetermined initial state is set.

[0026] According to the invention, a computer program is also provided, comprising instructions that cause the centering device to execute the aforementioned method. The computer program comprises instructions that, for example, form a program code. When the program code is executed by a computer or a computer network, the computer is prompted to execute the previously described method or at least one embodiment thereof.

[0027] A further aspect of the invention relates to a computer-readable medium (storage medium) on which the aforementioned computer program or its instructions are stored. To execute the computer program, a computer or a computer network can access the computer-readable medium and read its contents. The storage medium is designed, for example, as a data memory, in particular at least partially as a volatile or non-volatile data memory. A non-volatile data memory can be a flash memory and / or an SSD (solid state drive) and / or a hard disk. A volatile data memory can be a RAM (random access memory). The instructions can be present, for example, as source code of a programming language and / or as assembler and / or as binary code.

[0028] A further aspect of the invention relates to a control device which is designed to carry out the steps of at least one embodiment of the method described above. For this purpose, the control device can have a computing unit for electronic data processing, such as a processor. The computing unit can comprise at least one microcontroller and / or at least one microprocessor. The computing unit can be embodied as an integrated circuit and / or microchip. Furthermore, the control device can comprise an (electronic) data memory or a memory unit. Program code which encodes the steps of the respective embodiment of the respective method can be stored on the data memory. The program code can comprise the control data for the respective laser.The program code can be executed by the computing unit, causing the control device to execute the respective embodiment. The control device can be embodied as a control chip or control unit. The control device can be comprised, for example, of a computer or computer network.

[0029] Further features and advantages of one of the described aspects of the invention may arise from the further development of another aspect of the invention. The features of the embodiments of the invention may thus be present in any combination with one another, unless explicitly described as mutually exclusive.

[0030] Additional features and advantages of the invention are described below with reference to the figure(s) in the form of advantageous exemplary embodiments. The features or combinations of features of the exemplary embodiments described below can be present in any combination with one another and / or with the features of the embodiments. This means that the features of the exemplary embodiments can supplement and / or replace the features of the embodiments, and vice versa. Thus, the invention also encompasses and discloses configurations that are not explicitly shown or explained in the figures, but which emerge and can be produced from the exemplary embodiments and / or embodiments through separate combinations of features.Thus, embodiments are also considered to be disclosed that do not have all the features of an originally formulated claim or that go beyond or deviate from the combinations of features set forth in the claims' references. The embodiments are shown in: Fig. 1 is a schematic representation of a centering device according to an exemplary embodiment; Fig. 2 a schematic representation of a treatment device with a centering device according to an exemplary embodiment.

[0031] In the figures, identical or functionally identical elements are provided with the same reference numerals.

[0032] In Fig. 1 shows a schematically illustrated centering device 12 for determining the centering of a visual axis of an eye 14 according to an exemplary embodiment. This means that the centering device 12 can be designed to center the visual axis of the eye, which indicates a region of sharpest vision, or to determine the associated alignment of the eye 14 such that the visual axis coincides coaxially with a beam path of a diagnostic and / or treatment device, in particular when the beam path or beam output of the diagnostic and / or treatment device is in a neutral position. For this purpose, the centering device 12 can have a first color source 16, a second color source 18, a control device 20, and a detection device 22.

[0033] The first color source 16 can be configured to generate a first color signal 17. For this purpose, the first color source 16 can be configured, for example, as a light-emitting diode and / or laser. The color signal 17 generated by the first color source 16 can be provided in particular in a visible spectral range and preferably have a wavelength above 600 nanometers. In other words, the first color signal can be generated, for example, in a red or orange spectral range.

[0034] The second color source 18 can be configured to generate a second color signal 19, wherein the second color signal 19 has a different wavelength than the first color signal 17. The second color signal 19 can also be provided in the visible spectral range and preferably has a wavelength below 500 nanometers, with a wavelength difference between the color signals 17, 19 preferably being greater than 200 nanometers. This means that the second color signal 19 can be emitted, for example, in a blue or green spectral range.

[0035] The two color signals 17, 19 can then be combined in a beam path of the centering device 12, for example by a mirror 24. The mirror 24 can preferably be designed as a partially transparent mirror and / or dichroic mirror or filter.

[0036] The color signals 17, 19 can then be forwarded via the common beam path of the centering device 12 to an eye interface 26, wherein the eye interface 26 provides an output of the color signals 17, 19 to the outside and enables irradiation into the eye 14. For example, a contact element can be provided at the eye interface 26, to which the eye 14 can be placed.

[0037] In order to determine whether a visual axis of the eye 14 is centered relative to the beam path of the respective color signals 17, 19, it can be checked whether the color signals 17, 19 overlap on a visual axis of the eye 14. Due to chromatic aberration, if the visual axis of the eye 14 is decentered, there is a different degree of refraction between the first color signal 17 and the second color signal 19 in the eye 14, whereby a transverse shift of the color signals 17, 19 occurs due to the decentering and thus the respective color signals 17, 19 impinge at different positions in the retina. However, if the common beam path of the color signals 17, 19 coincides coaxially with the visual axis or achromatic axis, the two color signals 17, 19 impinge at a common position on the retina.It should be noted here that chromatic aberration also occurs when the visual axis coincides with the optical path. However, this only acts longitudinally to the visual axis / optical path, resulting in no transverse shift, so that the projections of the color signals 17 and 19 on the retina overlap at one position.

[0038] To determine that the color signals 17, 19 lie on the visual axis of the eye 14, the control device 20 can check different superposition criteria, which indicate an overlay of the color signals on the visual axis. For example, a projection of the color signals 17, 19 on the retina can be captured by the capture device 22, which can comprise, for example, an ophthalmoscopy device. These images can then be checked by the control device 20 to determine whether the color signals 17, 19 overlap on the retina. If this is the case, the overlay criterion can be met, whereby the control device 20 can control the capture device 22 to determine an eye alignment. For example, the capture device 22 can additionally comprise a camera that takes an image of the eye 14 at the moment the overlay criterion is met.From this image, the orientation of the eye 14 in relation to the centering device 12 can then be determined, for example using landmarks, in particular using a pupil center and / or characteristics of the iris, which corresponds to a centering of the visual axis.

[0039] Another possibility for verifying the superposition criterion is the determination of Purkinje images of the color signals 17, 19, which can also be recorded, for example, by the detection device 22. If the Purkinje images of the respective color signals 17, 19, in particular the first and fourth Purkinje images of the respective color signals 17, 19, are superimposed, it can be provided that the control device 20 controls the detection device 22 to determine the eye alignment.

[0040] Alternatively or additionally, the centering device 12 can also include an input device 28 that can be manually operated by a user, in particular a patient. For example, the input device 28 can be designed as a button or push-button. If the patient perceives the two color signals 17, 19 to be superimposed, the patient can manually trigger the detection of the eye alignment via the input device 28.

[0041] The detected eye alignment can, for example, be stored in a storage device (not shown) of the centering device 12 and / or transmitted to further therapeutic and / or diagnostic devices that can use the eye alignment and thus the centering of the visual axis of the eye 14 for further treatment or diagnostic steps.

[0042] In Fig. 2 shows a schematically illustrated treatment device 10 according to an exemplary embodiment. The treatment device 10 has an ophthalmic laser 30, for example, for correcting a cornea of ​​an eye 14. For example, a correction profile, in particular a solid body or lenticule (not shown), can be defined by control data, which can be separated from the cornea by means of photodisruption and / or ablation. For example, for separating the lenticule, boundary surfaces can be specified in the control data, on which boundary surfaces a cavitation bubble path can be generated to separate the lenticule from the cornea.

[0043] It can be seen that, in addition to the laser 30, a control device 32 of the treatment device 10 can be configured for the laser 30, so that the laser can emit pulsed laser pulses, for example, in a predefined pattern to generate the correction profile or the boundary surfaces. Alternatively, the control device 32 of the treatment device and the control device 20 of the centering device 12 can be configured as a common control unit.

[0044] Furthermore, the Fig.1, the laser beam 34 generated by the laser 30 can be deflected into different positions by means of a beam device 36, namely a beam deflection device, such as a rotary scanner, wherein a neutral position can preferably be defined in which the laser beam 34 is centered or emitted centrally. The beam deflection device 36 can also be controlled by the control device 32 to generate the correction profile or the boundary surfaces.

[0045] The laser 30 shown can preferably be a photodisruptive and / or ablative laser configured to emit laser pulses in a wavelength range between 300 nm and 1400 nm, preferably between 700 nm and 1200 nm, with a respective pulse duration between 1 fs and 1 ns, preferably between 10 fs and 10 ps, ​​and a repetition frequency greater than 10 kHz, preferably between 100 kHz and 100 MHz. The control device 32 optionally also includes a memory device (not shown) for at least temporarily storing at least one control data set, wherein the control data set(s) comprise control data for positioning and / or focusing individual laser pulses in the cornea.The position data and / or focusing data of the individual laser pulses, i.e. the correction profile of the lenticule to be separated, is generated on the basis of predetermined control data, in particular from previously measured refractive error data, in particular a previously measured topography and / or pachymetry and / or the morphology of the cornea.

[0046] The treatment device 10 can further comprise the centering device 12. In this case, it can be provided that the eye interface 26 of the centering device 12 is the same as that of the treatment device 10. In particular, the eye interface 26 can comprise a fixation device 38, preferably a suction ring. The fixation device 38 can be designed to fix the eye 14 in a position and / or in an eye alignment.

[0047] Particularly preferably, the eye 14 can be docked to the fixation device 38 of the eye interface 26, with the centering device 12 checking the superposition of the color signals 17, 19. If the superposition of the color signals 17, 19 is present on the visual axis, the control device 20 and / or the control device 32 can additionally control the fixation device 38 to fix the centered eye. This means, for example, that a suction device can be started that sucks in the eye using negative pressure and thus fixes it. Treatment of the centered eye 14 can then be started using the treatment device 10.

[0048] Overall, the examples show how the invention can provide automatic centering of a visual axis of an eye.

Claims

[1] Centering device (12) for determining a centering of a visual axis of an eye (14) with respect to a beam path, wherein the centering device (12) has at least two color sources (16, 18), a control device (20) and a detection device (22), wherein the color sources (16, 18) are arranged in the beam path of the centering device (12), wherein a respective color signal (17, 19) in a visible spectral range can be output by the color sources (16, 18) via the beam path to an eye interface (26), wherein a wavelength of the respective color signals (17, 19) differs, and wherein the control device (20) is designed to control the detection device (22) to determine an eye alignment if an overlay criterion is present which indicates a overlay of the color signals (17, 19) on the visual axis. [2] Centering device (12) according to claim 1, wherein the color sources (16, 18) are designed as white light sources with respective color filters. [3] Centering device (12) according to claim 1, wherein the color sources (16, 18) are designed as light-emitting diodes and / or lasers. [4] Centering device (12) according to one of the preceding claims, wherein the wavelengths of the color signals (17, 19) are located at different ends of the visible spectral range, in particular one color signal (17) in a red or orange spectral range and the other color signal (19) in a blue or green spectral range. [5] Centering device (12) according to one of the preceding claims, wherein one of the color signals (19) has a wavelength in the visible spectral range below 500 nm and / or the further color signal (17) has a wavelength in the visual spectral range above 600 nm. [6] Centering device (12) according to one of the preceding claims, wherein the wavelengths of the color signals (17, 19) have a spacing of at least 200 nm. [7] Centering device (12) according to one of the preceding claims, wherein the detection device (22) is additionally designed to determine a superposition of the color signals (17, 19) on a retina, wherein the superposition criterion is present upon determination of the superposition. [8] Centering device (12) according to one of the preceding claims, wherein the detection device (22) is additionally designed to determine a superposition of Purkinje images of the color signals (17, 19), wherein the superposition criterion is present upon determination of the superposition. [9] Centering device (12) according to one of the preceding claims, wherein the detection device (22) is designed to determine the eye alignment by means of a recording of the eye (14) and a determination of landmarks in the recording, in particular a pupil center and / or characteristics of the iris. [10] Centering device (12) according to one of the preceding claims, wherein the centering device (12) has an input device (28) which is designed to generate a control signal for the control device (20), wherein the superposition criterion is present by the generated control signal. [11] Treatment device (10) with at least one ophthalmological laser (30) for the separation of a corneal volume of a human or animal eye (14) by means of optical breakdown, in particular by means of photodisruption and / or ablation, and / or for a laser-induced structural change, in particular a laser-induced refractive index change and / or laser-induced cross-linking, and a centering device (12) according to one of the preceding claims. [12] Treatment device (10) according to claim 11, wherein the eye interface (26) has a fixing device (38) for the eye (14), in particular a suction ring, wherein the control device (20) is designed, when the superposition criterion is present, in addition to controlling the fixing device (38) for fixing the eye (14). [13] Method for determining a centration of a visual axis of an eye (14), with a centration device (12) according to one of claims 1 to 10, wherein a respective color signal (17, 19) in a visible spectral range and with different wavelengths is generated by at least two color sources (16, 18) and is output to an eye interface (26) via an at least partially common beam path, wherein a control device (20) checks for the presence of an overlay criterion by which a superposition of the color signals on a visual axis of an eye (14) located at the eye interface (26) is indicated, wherein a detection device (22) determines an eye alignment if the overlay criterion is present. [14] Computer program comprising instructions causing the centering device (12) according to any one of claims 1 to 10 to carry out a method according to 13. [15] A computer-readable medium on which a computer program according to claim 14 is stored.

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