Method for positioning optical axis of laser-assisted ophthalmic procedure without corneal marking

Abstract

A method for finding an optical axis position prior to eye docking for use in a corneal microlens procedure for tracking optical axis position displacement during docking without ink marking the optical axis position at the center of the cornea using ink or other material, and centering the microlens cutout pattern at the viewing axis position after docking. The two docking illumination beams illuminate on the surface of the eye at an inclined angle and a first eye image is taken before docking while the eye gazes at the fixed light of the laser system. A second eye image is taken after docking. Corneal vertex positioning before docking is obtained based on the two reflected light spots of the docking illumination light. A pupil center is obtained in both images. The post-docking corneal apex is then calculated from the pre-docking corneal apex positioning and the pre-docking and post-docking pupil center positioning.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to U.S. Patent Application No. 18 / 190,061, filed March 24, 2023, the entire contents of which are incorporated herein by reference. Background Technology

[0003] Technical Field This invention relates generally to laser-assisted ophthalmic procedures, and more specifically, to a method for locating the visual axis (corneal apex) of a patient's eye without marking the cornea for ophthalmic laser surgery (such as corneal microlens removal).

[0004] With recent advancements in laser technology, laser surgery has gradually become the preferred technique for ophthalmic procedures involving vision correction. Different laser ophthalmic surgical systems utilize different types of laser beams for various procedures and indications. These include, for example, ultraviolet lasers, infrared lasers, and near-infrared ultrashort pulse lasers. Ultrashort pulse lasers emit radiation with pulse durations ranging from as short as 10 femtoseconds to as long as 3 nanoseconds and wavelengths between 300 nm and 3000 nm.

[0005] Specifically, since their introduction into ophthalmology, femtosecond lasers have been widely used in femtosecond laser-assisted in situ keratomileusis (FS-LASIK) refractive procedures to treat myopia and astigmatism, and in laser-assisted cataract surgery. One of the main advantages of femtosecond lasers compared to mechanical techniques is their superior precision and reproducibility during anterior capsulotomy and lens fragmentation, as well as in the creation of lamellar flaps. The short pulse duration and high repetition rate of femtosecond lasers allow for the application of lower energy levels than those used for picosecond and nanosecond lasers in generating the laser-induced plasma and cavitation bubbles required for tissue photoanatomy. This lower pulse energy, combined with the low absorption rate of laser light by tissue in the near-infrared wavelength range, significantly reduces thermal effects and collateral damage to adjacent tissues in femtosecond laser-assisted ophthalmic procedures.

[0006] Surgical procedures used to reshape the cornea include laser-assisted in situ keratomileusis (LASIK), refractive keratomileusis (PRK), and lenticule extraction. In the LASIK procedure, an ultrashort-pulse laser is used to cut a corneal flap to expose the corneal stroma for photoablation with an ultraviolet beam from an excimer laser. The photoablation of the corneal stroma reshapes the cornea and corrects refractive conditions such as myopia, hyperopia, and astigmatism. In the PRK procedure, which does not create a flap, the epithelium is first removed, followed by the removal of some stromal material using an excimer laser. The epithelium will grow back within a few days after the procedure.

[0007] In corneal lenticule removal procedures, instead of using an excimer laser to ablate corneal tissue after creating a corneal flap, the technique involves tissue removal through two or more intersecting femtosecond laser incisions to form a lenticule for removal. The removal of the lenticule alters the shape and refractive power of the cornea to achieve visual correction. Lens removal can be performed with or without forming a corneal flap. Using a flapless procedure, a refractive lenticule is formed within an intact portion of the anterior cornea and removed through a small incision.

[0008] In ophthalmic laser surgeries such as femtosecond laser corneal microlentimetry, it is important to center the incision pattern along the visual axis of the patient's eye. Decentering of the microlens (e.g., more than 300 μm) can degrade visual quality. Summary of the Invention

[0009] The present invention relates to a method and related apparatus for positioning the visual axis of the cornea, which substantially avoids one or more problems caused by the limitations and disadvantages of related technologies.

[0010] The purpose of this invention is to locate the visual axis for corneal microlens removal procedures without marking the cornea with ink.

[0011] Additional features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from that description, or may be learned by practice of the invention. The objects and other advantages of the invention will be realized and obtained by means of the structures particularly pointed out in the written description, its claims, and the accompanying drawings.

[0012] To achieve the above objectives, the present invention provides a method for locating the corneal apex of a patient's eye using an ophthalmic laser system, the method comprising: (a) coupling a patient interface device to the ophthalmic laser system; (b) positioning the patient's eye and the patient interface device relative to each other such that the eye is located below the patient interface device within a predetermined distance range, without coupling the patient interface to the eye; (c) generating a stationary light beam that exits the ophthalmic laser system along the optical axis of the ophthalmic laser system; (d) generating one or more docking illumination beams, each of the one or more docking illumination beams exiting the ophthalmic laser system in a direction having a predetermined spatial relationship with the optical axis of the ophthalmic laser system; (e) when the eye is not coupled to the patient interface device and the eye is being injected through the patient interface device... (f) Obtaining a first image of the eye when a fixed light and one or more docking illumination beams are incident on the eye; (g) Coupling a patient interface device to the eye; (h) Obtaining a second image of the eye when the patient interface device is coupled to the eye; (h) Based on the first image, identifying the location of one or more light spots representing reflected light from one or more docking illumination beams, and calculating the pre-docking corneal vertex position based on the location of the one or more light spots; (i) Based on the first image, identifying the pupil of the eye, and calculating the pre-docking pupil center position; (j) Based on the second image, identifying the pupil of the eye, and calculating the post-docking pupil center position; and (k) Calculating the post-docking corneal vertex position based on the pre-docking corneal vertex position, the pre-docking pupil center position, and the post-docking pupil center position.

[0013] In another aspect, the present invention provides a method for locating the corneal apex of a patient's eye in an ophthalmic laser system, the method comprising: (a) generating a fixed light source of the ophthalmic laser system, the fixed light exiting the ophthalmic laser system along the optical axis of the ophthalmic laser system; (b) generating one or more corresponding docking illumination beams of the ophthalmic laser system through one or more docking illumination sources, each of the one or more docking illumination beams exiting the ophthalmic laser system in a direction having a predetermined spatial relationship with the optical axis of the ophthalmic laser system; and (c) when a patient interface device is coupled to the ophthalmic laser system, the eye is positioned below the patient interface within a predetermined distance range, the eye is looking at the fixed light through the patient interface device, and one or more docking illumination sources are... (d) When the beam is incident on the eye, a first image of the eye is obtained by a camera of the ophthalmic laser system; after the patient interface is coupled to the eye, a second image of the eye is obtained by a camera; and by a controller of the ophthalmic laser system: (e) based on the first image, the location of one or more points of light representing the reflected light of one or more docking illumination beams is identified, and the pre-docking corneal vertex position is calculated based on the location of the one or more points of light; (f) based on the first image, the pupil of the eye is identified, and the pre-docking pupil center position is calculated; (g) based on the second image, the pupil of the eye is identified, and the post-docking pupil center position is calculated; and (h) the post-docking corneal vertex position is calculated based on the pre-docking corneal vertex position, the pre-docking pupil center position, and the post-docking pupil center position.

[0014] In another aspect, the present invention provides an ophthalmic laser system comprising: a fixed light source configured to generate a fixed beam that exits the ophthalmic laser system along an optical axis at a beam exit point; one or more docking illumination sources configured to generate one or more docking illumination beams, each of the one or more docking illumination beams exiting the ophthalmic laser system in a direction having a predetermined spatial relationship with the optical axis of the ophthalmic laser system; a patient interface device coupled to the beam exit and having an optical window through which the fixed beam and one or more docking illumination beams pass; a camera configured to capture reflected light from an eye disposed below the patient interface device; and a controller coupled to the camera and programmed to perform the following steps: (a (a) When the eye is positioned below the patient interface within a predetermined distance, the eye is looking at a fixed light through the patient interface device, and one or more docking illumination beams are incident on the eye, control the camera to obtain a first image of the eye; (b) after the patient interface is coupled to the eye, control the camera to obtain a second image of the eye through the camera; (c) based on the first image, identify the location of one or more light spots representing the reflected light of one or more docking illumination beams, and calculate the pre-docking corneal vertex position based on the location of the one or more light spots; (d) based on the first image, identify the pupil of the eye, and calculate the pre-docking pupil center position; (e) based on the second image, identify the pupil of the eye, and calculate the post-docking pupil center position; and (f) based on the pre-docking corneal vertex position, the pre-docking pupil center position, and the post-docking pupil center position, calculate the post-docking corneal vertex position.

[0015] In a preferred embodiment, the step of calculating the corneal vertex position after docking uses the following formula:

[0016] (XA',YA')=(γ*XA+XB'-γ*XB,γ*YA+YB'-γ*YB), where (XA',YA') represents the corneal vertex position after docking, (XA,YA) represents the corneal vertex position before docking, (XB,YB) represents the pupil center position before docking, (XB',YB') represents the pupil center position after docking, and γ is the magnification correction factor between the first and second images.

[0017] In a preferred embodiment, the step of generating one or more docking illumination beams includes: generating two docking illumination beams located in a plane passing through the optical axis, at an angle relative to the optical axis, with one docking illumination beam on each side of the optical axis, and the two docking illumination beams being symmetrical with respect to the optical axis; and the step of calculating the pre-dock corneal vertex position includes: identifying the locations of two light spots representing the reflected light of the two docking illumination beams; and calculating the pre-dock corneal vertex position as the center of the line segment connecting the locations of the two light spots.

[0018] It should be understood that the foregoing general description and the following detailed description are merely exemplary and illustrative, and are intended to provide further explanation of the claimed invention. Attached Figure Description

[0019] Figure 1 The illustration schematically illustrates the intracorneal microlens and its relationship with the visual axis and fixed light in an ophthalmic corneal microlens procedure according to an embodiment of the present invention.

[0020] Figure 2 A method for positioning the visual axis of a corneal microlens procedure according to an embodiment of the present invention is illustrated schematically.

[0021] Figure 3A and Figure 3B An example of a single-piece patient interface device that can be used in embodiments of the present invention is shown. Figure 3B This is a bottom view of the patient interface, showing the fixed light as it appears through the optical window of the patient interface.

[0022] Figure 4 The relationship between a fixed beam and two docking illumination beams in an ophthalmic laser system according to an embodiment of the present invention is illustrated schematically.

[0023] Figures 5A to 5D An embodiment of the invention is illustrated in Figure 2 Examples of images taken during the process. Detailed Implementation

[0024] Embodiments of the present invention provide a method for locating the visual axis position during corneal microlentimetry before eye docking. This method tracks visual axis displacement during docking without marking the visual axis position at the center of the cornea with ink or other substances, and centers the microlentimetry incision pattern at the visual axis position after docking. Marking the visual axis with ink on the corneal surface not only adds to the procedural steps but also increases the risk of corneal surface roughness.

[0025] Here, docking refers to the process of coupling a patient's eye to the laser delivery head of an ophthalmic laser system via a patient interface device. During the procedure, the patient interface device mechanically and optically couples the eye to the optics of the laser system.

[0026] The eye's optics have four refractive surfaces: the anterior corneal surface, the posterior corneal surface, the anterior lens surface, and the posterior lens surface (as well as refraction due to the lens's gradient refractive index). The corneal microlens procedure addresses the refraction at the anterior corneal surface. To best maintain the optical axis of the entire eye's optics, the corneal microlens should be centered at the optical axis on the anterior corneal surface. For example... Figure 1 As shown, when the eye is focused on the fixation beam, the optical axis O of the anterior corneal surface is parallel to the direction of the fixation beam F, which typically crosses the anterior corneal surface at the corneal apex. The fixation beam (sometimes called the aiming beam) is a collimated beam generated by an ophthalmic laser system that travels along the same optical path as the therapeutic laser beam at the beam exit (i.e., the location where the beam leaves the beam delivery head). This is typically used to allow the patient to guide their eye toward the target direction as instructed by the surgeon. In this case, as... Figure 1 As shown, the corneal vertex A is the position where the visual axis O passes through the cornea, and it is the position where the center C of the corneal microlens should be aligned with it.

[0027] Various techniques have been used in ophthalmic laser systems for corneal microlentifold alignment. One known method includes the following steps: Step 1: The patient focuses on the fixed beam of the ophthalmic laser system. Step 2: The normal reflection of the fixed beam at the anterior cornea indicates the position of the corneal apex. This is the point where the microlentifold should be centered. Step 3: The position of the bed on which the patient lies is adjusted so that the corneal apex is centered on the laser optical axis. This adjustment can be done manually by the surgeon or automatically by the laser system. Step 4: The surgeon moves the bed upward so that the eye is close to the patient interface device already mounted on the laser system. Step 5: The surgeon couples the patient interface to the eye. For example, the patient interface can be a patient interface coupled to the eye using a suction ring, and the surgeon activates a vacuum suction system to suction the patient interface onto the eye. Step 6: A microlentifold incision is performed using a therapeutic laser beam, wherein the incision pattern is centered at the center of the patient interface, which is also the optical axis of the laser system.

[0028] The problem with this technique is that if the corneal apex is not centered at the patient interface, there is no centering adjustment after aspiration because the apex was initially not centered or because it was moved during aspiration. This is one of the main problems with this traditional method.

[0029] Another known technique for centering corneal microlenses involves the following steps: Step 1: Before placing the patient interface, the surgeon instructs the patient to gaze at a fixed light from a microscope separate from the ophthalmic laser system and manually mark the corneal apex or pupil center using a corneal marking tool with corneal ink. Step 2: After coupling the patient interface to the eye (butt and flatten), the surgeon manually adjusts the microlens incision pattern to center it on the central corneal mark. This is done by: viewing an image of the eye taken by a camera from the laser system; determining the ink mark position; and moving the programmed incision pattern to be performed by the laser system so that it is centered on the ink mark. The disadvantage of this method is that it adds a corneal marking step to the entire procedure, and it may introduce surface roughness or even damage to the corneal field of vision.

[0030] An embodiment of the present invention provides a method, as described below. Figure 2 The method described herein is used to locate the visual axis of the cornea without marking the cornea with ink and to center the microlens incision pattern accordingly.

[0031] like Figure 2 As shown, in step 1, the patient interface is coupled to the beam delivery head of the ophthalmic laser system and is ready to be coupled to the patient's eye. The patient interface is preferably a one-piece patient interface, i.e., a patient interface constructed as a single, integrated structure, an example of which is shown in... Figure 3A (Perspective) and Figure 3B Example shown in the bottom view. Figures 3A to 3B As shown, the one-piece patient interface 30 has a tapered body with an upper end 31 and a lower end 32. The upper end is configured to be coupled to a beam delivery head of a laser system, and the lower end is configured to be coupled to the patient's eye, for example, via a suction ring 33 located at the lower end. The suction ring is a soft and flexible material forming an annular suction channel, which can apply suction force to the surface of the eye to hold the eye to the patient interface. The patient interface has a central optical window 34 covered by a planarization lens (also indicated by reference numeral 34), through which various beams from the laser system are delivered to the eye.

[0032] Some ophthalmic laser systems use a two-piece patient interface, consisting of a first piece configured to couple to the laser system's beam delivery head and a second piece (e.g., via an aspiration ring) configured to couple to the eye. The first and second pieces are separate components, coupled to each other as a final step in eye docking. The method described herein is primarily applicable to single-piece patient interfaces. With a single-piece patient interface, aspiration and flattening are performed simultaneously as the final step in docking; the method of this embodiment restricts and effectively tracks movement of the visual axis (corneal apex position) before and after aspiration and flattening. However, it should be noted that the method described herein is applicable if a two-piece patient interface is used, but the two pieces are joined together before the lower piece is coupled to the eye, since aspiration and flattening are the final steps in docking.

[0033] Re-reference Figure 2 In step 2, the beam delivery head, on which the patient interface is mounted, is positioned approximately aligned with the eyes of the patient lying on the bed and lowered to a position close to but not yet in contact with the eyes (e.g., leaving a distance of up to 75 mm, or more preferably up to 11 mm, between the lower surface of the flattening lens and the apex of the cornea). Alternatively, the beam delivery head may be lowered to a position where the flattening lens just touches and slightly presses against the eye, for example, lowered to a position up to 0.6 mm below the unflattened surface of the corneal apex. Within this preferred range, i.e., a distance of -0.6 mm to 11 mm between the flattening lens and the corneal apex, the light spots of the two mating illumination beams can be clearly seen (described in more detail later). The positioning of the beam delivery head can be accomplished by moving the beam delivery head and / or moving the bed. The surgeon then instructs the patient to look at the fixed light of the laser system through the patient interface. Figure 3B This is a bottom view of the patient interface, illustrating the fixed light F (e.g., a red flashing dot) as it is presented to the patient. When the patient fixates on the fixed light, which has a very narrow field of view, the visual axis of the eye is aligned with the optical axes of the fixed light and the laser system. In this case, the vertex A of the cornea is where the visual axis O passes through the cornea, and is the position where the center C of the corneal microlens should be aligned (see [reference]). Figure 1 ).

[0034] In step 3, two collimated illumination beams generated by the ophthalmic laser system are guided onto the eye through the patient interface. For example... Figure 4 Schematic illustration shows that the optical paths of the two docking illumination beams D1 and D2 lie in the plane passing through the optical axis of the laser system at the beam exit (which is also the optical path of the fixed beam F), at an angle relative to the optical axis, with one docking illumination beam on each side of the optical axis, and the two docking illumination beams are symmetrical with respect to the optical axis (i.e., at the same angle of inclination). Figure 4In this context, the plane is the plane of the drawing. Two docking illumination beams, D1 and D2, are generated by two docking illumination sources 45 and 46 of the ophthalmic laser system 40.

[0035] like Figure 4 As illustrated schematically, the ophthalmic laser system 40 also includes a laser source 41 for generating a therapeutic laser beam, and a beam scanner or scanning assembly (also made of...) for scanning the focal point of the therapeutic laser beam in the lateral and longitudinal directions. Figure 4 The laser system 40 includes a fixed light source 42 (represented by box 41 in the diagram) that generates a fixed beam, and a camera 43 that receives reflected light from the eye to generate an image of the eye. The laser system 40 also includes optical components that combine the optical paths of the therapeutic laser and the fixed light into a common optical path at the beam exit (in...). Figure 4 (marked as F), and the optical path of the reflected light traveling toward camera 43 is separated from the optical paths of the therapeutic laser and the stationary light. Figure 4 In the example shown, the optical components include two beam splitters 47A and 47B, but other suitable beam splitter arrangements and / or other suitable optical components can also be used to achieve the above-described function. For example, beam splitter 47B can alternatively be positioned above beam splitter 47A to reflect the stationary light onto the upper side of beam splitter 47A. In another alternative configuration, the common optical path of the therapeutic laser and the stationary light can be in a direction perpendicular to the drawing, and beam splitter 47A is positioned in an orientation used to reflect them toward the beam exit. Many other optical configurations are possible and can be implemented by those skilled in the art.

[0036] Re-reference Figure 2 Step 3 further includes capturing a first image of the eye with camera 43 by capturing reflected light from the eye while the patient is looking at the fixed light and while the two docking illumination beams are incident on the anterior corneal surface. This image will contain images of eye structures such as the pupil and iris, as well as two light spots, which are the reflected light from the two docking illumination beams on the anterior corneal surface. From this image, the following information is obtained: First, the positions of the two reflected light spots of the docking illumination beams are measured, and the center of the line segment connecting the two light spots is calculated as the docking anterior corneal apex position (XA, YA). This is based on the fact that when the eye is looking at the fixed light, the corneal apex is aligned with the fixed light, and the two incident points of the two docking illumination beams on the anterior corneal surface (which is a near-spherical surface) are symmetrical on both sides of the corneal apex. Second, the pupillary margin is fitted with a circle, and the center of the circle is calculated as the docking anterior pupil center position (XB, YB).

[0037] In step 4, the beam delivery head is further lowered so that the flattening lens contacts the corneal surface (unless the flattening lens has been sufficiently lowered to contact the corneal surface in step 2), and the lower end of the patient interface 30 is coupled to the eye, such as by bringing the suction ring 32 into contact with the eye and applying suction force to the suction ring. This achieves eye docking. The coupling of the suction ring to the eye results in the cornea being flattened (to a certain extent), and the corneal apex may be displaced due to asymmetry in suction pressure and / or asymmetry in the eye around the visual axis.

[0038] In step 5, after aspiration and flattening, a second image of the eye is captured using camera 43. Based on the second image, the pupil center position (XB', YB') after docking is calculated by fitting a circle to the pupil edge. The vector difference (XB'-XB, YB'-YB) between the pupil center after docking and the pupil center before docking is calculated as the corneal displacement before and after docking. By adding this displacement to the vertex position (XA, YA) before docking, the vertex position (XA', YA') after docking is calculated as follows:

[0039] (XA',YA')=(γ*XA+XB'-γ*XB,γ*YA+YB'-γ*YB)

[0040] Where γ is the magnification correction factor between the pre- and post-docking (first and second) images. In some embodiments, γ can be calculated as follows: γ = 0.0092 * H + 1, where H is the distance (in mm) between the planarization lens surface and the corneal vertex of the pre-docking image. H can be measured by any suitable measuring component within the beam delivery head and / or patient interface device.

[0041] Note that all coordinates described here are in the camera's frame of reference.

[0042] In step 6, with the patient's eye aligned with the laser system, the laser system centers the microlens incision pattern at the apex position (XA', YA') after alignment and performs a microlens incision according to the incision pattern. This includes generating a pulsed laser beam from laser source 41 and scanning the focal point of the pulsed laser beam within the eye tissue using the scanning components of the laser system. The scanning components may include one or more of, for example, a resonant scanner, a scan line rotator, a fast Z-scanner, a slow Z-scanner, an XY scanner, etc.

[0043] Figures 5A to 5D Examples of first and second images of the patient's eye taken in steps 3 and 5 are shown. Figure 5A The first image is taken in step 3, at which point the patient's eyes are focused on the stationary light, where two docking illumination beams illuminate the eyes immediately before the suction force is applied to the patient interface. Figure 5B Is with Figure 5A The same image, but with added annotations to indicate various features in the image, including the reflections of the two docking illumination beams D1 and D2, the vertex position (located at the center of the line segment connecting D1 and D2), the circle fitting the pupil, and the pupil center position. Figure 5C This is the second image taken in step 5 after suction and flattening have occurred. Note that the docking illumination beam has been turned off. Figure 5D Is with Figure 5C The same image, but with added annotations to indicate various features in the image, including the circle fitted to the pupil and the position of the pupil center. Figure 5A and Figure 5C China (and) Figure 5B and Figure 5D The small and large circles (in the middle) are reference circles with fixed positions in the camera's frame of reference. (Comparison) Figure 5B and Figure 5D It can be seen that the center of the pupil has shifted after suction and flattening, as can be seen by comparison. Figure 5B and Figure 5D This can be seen from the position of the pupil center relative to the small reference circle.

[0044] exist Figure 4 In one implementation, the two docking illumination beams are configured to be coplanar with and symmetrical about the optical axis of the laser system. In another implementation, the two docking illumination beams may have other spatial relationships with the optical axis, or other numbers of docking illumination beams with suitable spatial relationships with the optical axis may be used.

[0045] For example, in an alternative embodiment (not shown in the figure), only a single docking illumination beam is used, which propagates in a direction coaxial with the optical axis of the laser system (and therefore the stationary beam). This can be achieved, for example, using an additional beam splitter to couple the docking illumination beam to the optical axis of the laser system. In this case, in the first eye image taken in step 3, i.e., before the suction force is applied and while the patient is looking at the stationary beam, the corneal vertex is located as the spot of light reflected by the docking illumination beam. Therefore, the calculation of the corneal vertex position (XA, YA) in step 3 is simplified. Figure 2 The other steps of the process remain the same, including the calculations in step 5.

[0046] In another alternative implementation (not shown in the figure), the two docking illumination beams are coplanar with the optical axis but asymmetrical with respect to the optical axis, but this alternative arrangement would complicate the calculation of the vertex position based on the first image captured in step 3. Figure 2 The other steps of the process remain the same, including the calculations in step 5.

[0047] In another alternative embodiment (not shown in the figure), three, four, or more docking illumination beams are provided, which are located on a geometric cone around the optical axis (i.e., having the same tilt angle) and are uniformly or non-uniformly distributed around the optical axis. Such docking illumination beams will form three, four, or more light spots in the first image captured in step 3, which are uniformly or non-uniformly distributed around a circle (if uniformly distributed, they form a regular polygon), and the corneal vertex can be calculated as the center of the circle (or regular polygon). Figure 2 The other steps of the process remain the same, including the calculations in step 5.

[0048] In another alternative implementation (not shown in the figure), two pairs of docking illumination beams are provided, each pair being coplanar with the optical axis. The two planes of the two pairs of beams do not need to be perpendicular to each other. The tilt angles of the beams within each pair or between the two pairs do not need to be equal. Such docking illumination beams will form two pairs of light spots in the first image captured in step 3, and the corneal vertex can be calculated as the intersection of two line segments connecting the two pairs of light spots, respectively. Figure 2 The other steps of the process remain the same, including the calculations in step 5.

[0049] The various data processing steps described above, such as calculating the location of the docking illumination spot and the corneal vertex location in step 3, the circle fitting in steps 3 and 5, and calculating the vector difference and the corneal vertex position after docking in step 5, can be performed by the programmable controller 48, which is part of the ophthalmic laser system 40 (see [link to documentation]). Figure 4 The controller 48 is also coupled to various other components of the laser system 40, such as the laser source and beam scanner, and controls them to execute the slit pattern in step 6.

[0050] An alternative method for centering the microlenticule pattern without marking the cornea is to center the pattern at the center of the pupil. While the pupil center is not precisely aligned with the visual axis of the cornea, it is close to the cornea or close to the visual axis of the entire eye. Note that LASIK typically uses the pupil center, rather than the corneal apex, as the centering target. This alternative method does not require the use of two docking illumination lights or the calculations described above, except for fitting the pupil to a circle.

[0051] It should be noted that, using the corneal axis localization method described above, if astigmatism treatment is required, peripheral corneal marking may still be necessary to align the cornea's cylindrical axis. Marking the peripheral corneal axis is less important because it is not done within the visual field. Alternatively, if the iris image is taken from preoperative measurements (performed at a measurement system independent of the ophthalmic laser system 40) and matched with the iris image taken by the camera 43 of the laser system 40, the peripheral marking step can also be eliminated, thus providing a completely marker-free corneal microlentiolum procedure.

[0052] The methods described above for locating the visual axis and corneal apex can be used in wavefront-guided corneal microlens procedures, wherein the shape of the microlens is designed based on wavefront measurements of the eye and the designed visual correction amount.

[0053] It will be apparent to those skilled in the art that various modifications and variations can be made to the methods and related apparatus of the present invention without departing from the spirit or scope of the invention. Therefore, the present invention is intended to cover various modifications and variations falling within the scope of the appended claims and their equivalents.

Claims

1. A method for locating the corneal apex of a patient's eye using an ophthalmic laser system, comprising: (a) Couple the patient interface device to the ophthalmic laser system; (b) Positioning the patient's eye and the patient interface device relative to each other such that the eye is located below the patient interface device within a predetermined distance range, without coupling the patient interface to the eye; (c) Generate a fixed beam that exits the ophthalmic laser system along the optical axis of the ophthalmic laser system; (d) Generate one or more docking illumination beams, each of the one or more docking illumination beams leaving the ophthalmic laser system in a direction having a predetermined spatial relationship with the optical axis of the ophthalmic laser system; (e) Obtaining a first image of the eye when the eye is not coupled to the patient interface device, the eye is looking at the fixed light through the patient interface device, and the one or more docking illumination beams are incident on the eye; (f) Couple the patient interface device to the eye; (g) Obtaining a second image of the eye when the patient interface device is coupled to the eye; (h) Based on the first image, identify the location of one or more light spots representing the reflected light of the one or more docking illumination beams, and calculate the corneal vertex position before docking based on the location of the one or more light spots; (i) Based on the first image, identify the pupil of the eye and calculate the center position of the pupil before docking; (j) Based on the second image, identify the pupil of the eye and calculate the center position of the pupil after docking; as well as (k) Calculate the corneal vertex position after docking based on the corneal vertex position before docking, the pupil center position before docking, and the pupil center position after docking.

2. The method according to claim 1, wherein, Step (k) includes calculating the corneal vertex position after docking using the following formula: (XA',YA')=(γ*XA+XB'-γ*XB,γ*YA+YB'-γ*YB), Where (XA',YA') represents the corneal vertex position after docking, (XA,YA) represents the corneal vertex position before docking, (XB,YB) represents the pupil center position before docking, (XB',YB') represents the pupil center position after docking, and γ is the magnification correction factor between the first image and the second image.

3. The method according to claim 2, wherein, The magnification correction factor γ between the first image and the second image is calculated by γ = 0.0092 * H + 1, where H is the distance in mm between the planarization lens surface of the patient interface device and the corneal vertex when the first image is obtained.

4. The method according to claim 1, wherein, Step (d) includes: generating two docking illumination beams using two docking illumination sources, the two docking illumination beams being located in a plane passing through the optical axis, at an angle relative to the optical axis, with one docking illumination beam on each side of the optical axis, and the two docking illumination beams being symmetrical with respect to the optical axis; and Step (h) includes: identifying the locations of two light spots representing the reflected light of the two docking illumination beams; and calculating the position of the corneal vertex before docking as the center of the line segment connecting the locations of the two light spots.

5. The method according to claim 1, wherein, Step (d) includes: generating a docking illumination beam coaxial with the optical axis using a single illumination source; and Step (h) includes: identifying the location of a light spot representing the reflected light of the docking illumination beam; and calculating the location of the light spot as the position of the corneal vertex before docking.

6. The method according to claim 1, wherein, Step (i) includes fitting the pupil in the first image to a first circle and calculating the center of the first circle as the center of the pupil before docking, and step (j) includes fitting the pupil in the second image to a second circle and calculating the center of the second circle as the center of the pupil after docking.

7. A method for locating the corneal apex of a patient's eye in an ophthalmic laser system, comprising: (a) A fixed light is generated by a fixed light source of the ophthalmic laser system, and the fixed light leaves the ophthalmic laser system along the optical axis of the ophthalmic laser system; (b) One or more corresponding docking illumination beams are generated by one or more docking illumination sources of the ophthalmic laser system, each of the one or more docking illumination beams leaving the ophthalmic laser system in a direction having a predetermined spatial relationship with the optical axis of the ophthalmic laser system; (c) When the patient interface device is coupled to the ophthalmic laser system, the eye is positioned below the patient interface within a predetermined distance range, the eye is looking at the fixed light through the patient interface device, and the one or more docking illumination beams are incident on the eye, a first image of the eye is obtained by the camera of the ophthalmic laser system; (d) After the patient interface is coupled to the eye, a second image of the eye is obtained through the camera; as well as Through the controller of the ophthalmic laser system: (e) Based on the first image, identify the location of one or more light spots representing the reflected light of the one or more docking illumination beams, and calculate the pre-dock corneal vertex position based on the location of the one or more light spots; (f) Based on the first image, identify the pupil of the eye and calculate the center position of the pupil before docking; (g) Based on the second image, identify the pupil of the eye and calculate the center position of the pupil after docking; as well as (h) The corneal vertex position after docking is calculated based on the corneal vertex position before docking, the pupil center position before docking, and the pupil center position after docking.

8. The method according to claim 7, wherein, Step (h) includes calculating the corneal vertex position after docking using the following formula: (XA',YA')=(γ*XA+XB'-γ*XB,γ*YA+YB'-γ*YB), Where (XA',YA') represents the corneal vertex position after docking, (XA,YA) represents the corneal vertex position before docking, (XB,YB) represents the pupil center position before docking, (XB',YB') represents the pupil center position after docking, and γ is the magnification correction factor between the first image and the second image.

9. The method according to claim 8, wherein, The magnification correction factor γ between the first image and the second image is calculated by γ = 0.0092 * H + 1, where H is the distance in mm between the planarization lens surface of the patient interface device and the corneal vertex when the first image is obtained.

10. The method according to claim 7, wherein, Step (b) includes: generating two docking illumination beams using two docking illumination sources, the two docking illumination beams being located in a plane passing through the optical axis, at an angle relative to the optical axis, with one docking illumination beam on each side of the optical axis, and the two docking illumination beams being symmetrical with respect to the optical axis; and Step (e) includes: identifying the locations of two light spots representing the reflected light of the two docking illumination beams; and calculating the anterior corneal vertex position as the center of the line segment connecting the locations of the two light spots.

11. The method according to claim 7, wherein, Step (b) includes: generating a docking illumination beam coaxial with the optical axis using a single illumination source; and Step (e) includes: identifying the location of a spot representing the reflected light of the docking illumination beam; and calculating the location of the spot as the position of the corneal vertex before docking.

12. The method according to claim 7, wherein, Step (f) includes fitting the pupil in the first image to a first circle and calculating the center of the first circle as the center of the pupil before docking, and step (g) includes fitting the pupil in the second image to a second circle and calculating the center of the second circle as the center of the pupil after docking.

13. The method of claim 7, further comprising, via the controller: The microlens cut pattern is defined as centered at the vertex position after docking; and When the patient interface device is coupled to the eye, it controls the laser source and beam scanner assembly of the ophthalmic laser system to deliver a pulsed laser beam to the eye according to the microlens incision pattern.

14. An ophthalmic laser system, comprising: A fixed light source is configured to generate fixed light that exits the ophthalmic laser system along the optical axis at the beam exit of the ophthalmic laser system. One or more docking illumination sources are configured to generate one or more docking illumination beams, each of the one or more docking illumination beams exiting the ophthalmic laser system in a direction having a predetermined spatial relationship with the optical axis of the ophthalmic laser system; A patient interface device coupled to the beam exit and having an optical window through which the stationary light and the one or more docking illumination beams pass; A camera configured to capture reflected light from an eye positioned below the patient interface device; A controller, coupled to the camera, is programmed to perform the following steps: (a) When the eye is positioned below the patient interface within a predetermined distance range, the eye is looking at the fixed light through the patient interface device, and the one or more docking illumination beams are incident on the eye, the camera is controlled to obtain a first image of the eye; (b) After the patient interface is coupled to the eye, the camera is controlled to obtain a second image of the eye through the camera; (c) Based on the first image, identify the location of one or more light spots representing the reflected light of the one or more docking illumination beams, and calculate the pre-dock corneal vertex position based on the location of the one or more light spots; (d) Based on the first image, identify the pupil of the eye and calculate the center position of the pupil before docking; (e) Based on the second image, identify the pupil of the eye and calculate the center position of the pupil after docking; as well as (f) Calculate the corneal vertex position after docking based on the corneal vertex position before docking, the pupil center position before docking, and the pupil center position after docking.

15. The system according to claim 14, wherein, Step (f) includes calculating the corneal vertex position after docking using the following formula: (XA',YA')=(γ*XA+XB'-γ*XB,γ*YA+YB'-γ*YB), Where (XA',YA') represents the corneal vertex position after docking, (XA,YA) represents the corneal vertex position before docking, (XB,YB) represents the pupil center position before docking, (XB',YB') represents the pupil center position after docking, and γ is the magnification correction factor between the first image and the second image.

16. The system according to claim 15, wherein, The magnification correction factor γ between the first image and the second image is calculated by γ = 0.0092 * H + 1, where H is the distance in mm between the planarization lens surface of the patient interface device and the corneal vertex when the first image is obtained.

17. The system according to claim 14, wherein, The one or more docking illumination sources include two docking illumination sources configured to generate two docking illumination beams, the two docking illumination beams being located in a plane passing through the optical axis, at an angle relative to the optical axis, with one docking illumination beam on each side of the optical axis, and the two docking illumination beams being symmetrical with respect to the optical axis. and Step (c) includes: identifying the location of two light spots representing the reflected light of the two docking illumination beams; And the position of the corneal vertex before docking is calculated as the center of the line segment connecting the two light points.

18. The system according to claim 14, wherein, The one or more docking illumination sources include a single illumination source configured to generate a docking illumination beam coaxial with the optical axis; and Step (c) includes: identifying the location of a light spot representing the reflected light of the docking illumination beam; And the positioning of the corneal vertex position before docking as the light spot.

19. The system according to claim 14, wherein, Step (d) includes fitting the pupil in the first image to a first circle and calculating the center of the first circle as the center of the pupil before docking, and step (e) includes fitting the pupil in the second image to a second circle and calculating the center of the second circle as the center of the pupil after docking.

20. The system according to claim 14, wherein, The controller is also programmed to perform the following steps: The microlens cut pattern is defined as centered at the vertex position after docking; and When the patient interface device is coupled to the eye, it controls the laser source and beam scanner assembly of the ophthalmic laser system to deliver a pulsed laser beam to the eye according to the microlens incision pattern.

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