System and method for identifying a human visual axis

Abstract

The present disclosure relates generally to methods and apparatus for accurately identifying the visual axis of an eye. In one embodiment, a visual axis identification system includes a fixed light source, a camera, a processing system, and a multifocal lens. A patient passes their line of sight through the multifocal lens and focuses on a fixed light beam provided by the fixed light source. The fixed light beam creates two or more images on or near the patient's retina as it passes through the multifocal lens. The multifocal lens and / or the patient's eye are then moved relative to one another while the patient continues to keep their line of sight on the fixed light beam. When the centers of the multiple images coincide on the retina, the patient's visual axis can be located by determining the position of the optical center of the multifocal trial lens relative to the patient's eye.

Description

background Technical Field

[0002] The embodiments of this disclosure generally relate to methods and apparatus for visual characteristics, and more particularly, to methods and apparatus for accurately identifying the visual axis of the eye. Background Technology

[0004] Traditional presbyopia treatment techniques typically involve determining the relative position of the visual axes in each of a patient's eyes. Accurate determination of these axes is crucial for the effective placement of small-area bifocal, multifocal, and extended depth-of-focus (EDOF) intraocular lenses (IOLs). Even slight misalignment of these lenses can severely impede any benefits expected from surgical implantation. Other examples of presbyopia treatments that may also benefit from visual axis determination include LASIK, PresbyLASIK, or multifocal LASIK, as well as refractive corneal reshaping (PRK) surgery (to name just a few).

[0005] The visual axis is a person's actual line of sight; it is a straight line connecting the fovea (the small depression in the retina and the point of sharpest vision) of the eye to a fixed point in the patient's visual field. Therefore, measuring the visual axis is crucial for determining the placement of bifocal and multifocal lenses, as these lenses have a narrow field of view, and even slight misalignments can severely impair their function. Currently, there are no diagnostic devices for accurately and precisely determining the position of the visual axis. Instead, the position of the visual axis is generally approximated to the midpoint between the optical axis and the corneal apex, or the first Purkinje image, which is the reflection of fixed light on the outer surface of the cornea. This method is often inaccurate because the visual axis may be located far from the aforementioned midpoint (e.g., especially in damaged or abnormally shaped eyes).

[0006] Accordingly, there is a need in the art for improved methods and devices for identifying the visual axis of the eye. Summary of the Invention

[0007] This disclosure generally relates to methods and apparatus for accurately identifying the visual axis of the eye.

[0008] In some embodiments, a method is provided for determining the position of the visual axis of a patient's eye. The method includes placing a multifocal optical lens near the patient's eye, wherein the multifocal optical lens includes two or more optical powers and has corresponding and spatially coincident optical centers at its optical center. A fixed beam of light is generated and directed toward the patient's eye, forming two or more images near the patient's retina corresponding to the two or more optical powers of the multifocal lens. The method further includes capturing images of the patient's eye and the optical lens along the direction of the fixed beam of light and determining the X / Y position of the patient's eye relative to the X / Y position of the optical center of the multifocal optical lens. While the patient maintains their gaze on the fixed beam, the multifocal optical lens is moved along the X / Y direction until the centers of the two or more images coincide in the patient's field of vision. At this point, the position of the patient's visual axis is detected and located at the pupillary plane of the patient's eye, the position of which corresponds to the position of the optical center of the multifocal optical lens when viewed from the direction of the fixed beam of light. Attached Figure Description

[0009] To gain a more detailed understanding of the features described above in this disclosure, a more specific description of the briefly summarized disclosure can be obtained by referring to the embodiments, some of which are illustrated in the accompanying drawings. However, it should be noted that the drawings illustrate only exemplary embodiments and should not be construed as limiting their scope, and may allow for other equally effective embodiments.

[0010] Figure 1 A top-view cross-section of the human eye is shown.

[0011] Figure 2A A schematic diagram of a visual axis recognition system according to certain embodiments of this disclosure is shown.

[0012] Figure 2B A schematic diagram of an exemplary optical element for a visual axis recognition system according to certain embodiments of this disclosure is shown.

[0013] Figure 3A A schematic diagram of a portion of a visual axis recognition system according to certain embodiments of this disclosure is shown.

[0014] Figure 3B A schematic diagram of a portion of a visual axis recognition system according to certain embodiments of this disclosure is shown.

[0015] Figure 4A A schematic top view of a portion of a visual axis recognition system according to certain embodiments of this disclosure is shown.

[0016] Figure 4BA schematic top view of a portion of a visual axis recognition system according to certain embodiments of this disclosure is shown.

[0017] Figure 4C A schematic side view of a portion of a visual axis recognition system according to certain embodiments of this disclosure is shown.

[0018] Figure 5 Figure 2 illustrates certain embodiments of the use of FIG2 according to this disclosure. Figure 3A , Figure 3B and Figures 4A to 4C A block diagram of a method for a line-of-sight recognition system.

[0019] Figure 6A A schematic diagram of a portion of a visual axis recognition system according to certain embodiments of this disclosure is shown.

[0020] Figure 6B A schematic diagram of a portion of a visual axis recognition system according to certain embodiments of this disclosure is shown.

[0021] Figure 6C A schematic diagram of a portion of a visual axis recognition system according to certain embodiments of this disclosure is shown.

[0022] Figure 6D A schematic diagram of a portion of a visual axis recognition system according to certain embodiments of this disclosure is shown.

[0023] Figure 7A This illustrates certain embodiments of the application of this disclosure when using Figure 6A and Figure 6B When the visual axis recognition system is used, the patient's retina has multiple imaging spots.

[0024] Figure 7B This illustrates certain embodiments of the application of this disclosure when using Figure 6A and Figure 6B When the visual axis recognition system is used, the patient's retina has multiple overlapping imaging spots.

[0025] For ease of understanding, the same reference numerals have been used where possible to designate the same elements shared by the figures. It is contemplated that elements and features of one embodiment can be advantageously combined in other embodiments without further description. Detailed Implementation

[0026] This disclosure generally relates to methods and apparatus for accurately identifying the visual axis of an eye. In some embodiments, the visual axis identification system includes a fixed light source, a camera, a processing system, and a multifocal lens. The multifocal lens may be attached to a trial frame or non-patient device to be worn by a patient. In determining the position of the patient's visual axis, the patient focuses their line of sight through the multifocal lens onto a fixed beam of light provided by the fixed light source. The fixed beam of light creates two or more images on or near the patient's retina through the multifocal lens. The multifocal lens and / or the patient's eye are then moved relative to each other while the patient continues to maintain their line of sight on the fixed beam of light. When the centers of the multiple images coincide on the retina, the patient's visual axis can be located by determining the position of the optical center of the multifocal trial lens relative to the patient's eye.

[0027] Figure 1 A simplified cross-sectional top view of an exemplary human eye 100 is shown. Figure 1 The temporal and nasal sides of a human eye 100 are depicted for reference. Typically, the eye 100 includes a cornea 104, a pupil (its center 106 is shown), an iris 108, a natural lens 110, a ciliary muscle 112, and a retina 116. The pupillary axis 118 is perpendicular to the plane of the iris 108 and passes through the pupillary center 106.

[0028] Figure 1 The visual axis 120 is further depicted, extending from a fixed point P1 through the cornea 104 and pupil to the fovea 122 (which refers to the small depression in the retina 116). The center of the visual field is focused at the fovea 122, where the retinal cones are particularly concentrated, and therefore, visual acuity is highest along the visual axis 120. Accordingly, accurately determining the position 130 of the visual axis 120 is crucial for successful alignment of bifocal or multifocal corrective lenses. The position 130 of the visual axis 120 refers to the X / Y orientation or location of the point through which the visual axis 120 passes on the plane of the iris 108 or the pupillary plane. However, as mentioned earlier, no ophthalmic diagnostic device currently can precisely identify the position 130 of the visual axis 120.

[0029] Traditional ophthalmic techniques involve approximating the position 130 of the visual axis 120 as the midpoint between the pupillary center 106 and the corneal apex 132, or the first Purkinje image, defined as the position of the specular reflection from the anterior surface of the cornea 104 as viewed from a fixed light source. Current approximation techniques may result in ineffective or suboptimal corrective measures, such as misalignment of multifocal corrective lenses or presbyopia or PRK treatments. Embodiments of this disclosure provide improved systems and methods for accurately locating the intersection (position 130) of the visual axis 120 with the pupillary plane of the eye. Accordingly, embodiments of this disclosure can be used for corrective lens alignment and other ophthalmic procedures, including ophthalmic surgeries such as multifocal LASIK or multifocal PRK.

[0030] Figure 2 shows a simplified schematic diagram of an exemplary visual axis recognition system 200 according to some embodiments. The visual axis recognition system 200 includes a fixed light source 202, an imaging camera 204, an image processing system 206, and a multifocal lens 208. Typically, the fixed light source 202 and one or more associated optical relay devices 210 are configured to provide a fixed light beam 212 to the eye 100. For example, the fixed light source 202 may include one or more light-emitting diodes (LEDs) configured to emit the fixed light beam 212. Examples of other suitable light sources that can be used for the fixed light source 202 include incandescent lamps, etc. In some embodiments, the fixed light source 202 may provide a fixed light beam 212 having multiple wavelengths. The one or more optical relay devices 210 may include any suitable optical relay devices, such as relay lenses, beam splitters, filters, etc.

[0031] Imaging camera 204 may include any suitable digital imaging device or image detector, such as an eye-tracking camera or similar optical sensor, for capturing images of eye 100 and multifocal lens 208 and determining their position (e.g., X / Y translation position). In some embodiments, imaging camera 204 is an infrared optical sensor configured to track the X / Y position of eye 100 and multifocal lens 208. In this embodiment, eye 100 is illuminated by a fixed infrared light source 202. In some embodiments, imaging camera 204 is an optical sensor configured to track the movement of eye 100 by mapping and detecting the displacement (e.g., movement) of the vascular system (e.g., blood vessels) within eye 100, such as the vascular system within the sclera, which forms the white outer layer of eye 100.

[0032] Imaging camera 204 is communicatively coupled to image processing system 206 and can form a single device with it. For example, imaging camera 204 and image processing system 206 can be separate components within a single imaging device or system. Typically, imaging camera 204 is configured to capture images of eye 100 and transmit those images to image processing system 206 for analysis during use with visual axis recognition system 200. Image processing system 206 is configured to determine the X / Y position of eye 100 and the X / Y position of multifocal lens 208.

[0033] The determination of the X / Y position of the eye 100 by the image processing system 206 is performed relative to the X / Y position of the multifocal lens 208. The multifocal lens 208 can be any suitable type of multifocal optical lens. In some embodiments, the multifocal lens 208 is a multifocal lens with two or more focal powers, such as a bifocal lens. In some embodiments, the multifocal lens 208 is a multifocal lens with reflective coatings on its two or more sides. In further embodiments, the multifocal lens 208 includes diffractive optical elements, such as holographic elements, Fresnel lenses, etc. In still further embodiments, the multifocal lens 208 includes an axial pyramid or aspherical extended depth-of-focus lens, forming long or ultra-long focal lines (i.e., Bessel beams) instead of a single focal point. Figure 2B The text describes the formation of the super-telephoto line F. L An exemplary axial pyramid 218. Furthermore, it should be noted that although the multifocal lens 208 presents a certain elliptical shape, the multifocal lens 208 can have any suitable shape, such as the different shapes shown in the figures herein.

[0034] about Figures 3A to 3B , Figures 4A to 4C and Figures 6A to 6D Furthermore, examples of different types of multifocal lenses that can be used in the embodiments described herein are described in more detail. For example, such as Figures 3A to 3B and Figures 4A to 4C The depicted multifocal lens 308 includes at least two optical powers that create two distinct corresponding focal points: a first power 307 configured to correct refractive errors in the eye 100 for distance vision and a second power 309, or "additional power," for near vision. In some embodiments, the first power 307 corresponds to a single optical element or region, while the second power 309 corresponds to a separate second optical element or region. Furthermore, the first power 307 and the second power 309 have coincident (e.g., overlapping) optical centers at the optical center 314 of the multifocal lens 308. Thus, it can be said that the first power 307 and the second power 309 share the optical center 314. In some embodiments, the second power 309 is provided by a refractive element with a diameter smaller than the pupil diameter, such as a diameter less than about 1.5 mm, and an optical power of about 2 diopters.

[0035] like Figures 3A to 3B As shown and described, during the use of the visual axis recognition system 200, the multifocal lens 308 can be coupled (e.g., attached) to a non-patient device, such as an ophthalmic testing device. Therefore, movement of the non-patient device causes the multifocal lens 308 to shift relative to the patient's eye 100. Alternatively, the multifocal lens 308 can be coupled to a test frame 440 to be worn by the patient, such as... Figures 4A to 4CAs shown. Accordingly, when the patient is wearing the test frame 440, the rotation of the patient's head causes the multifocal lens 308 to shift relative to the eye 100, and this shift is proportional to the distance between the multifocal lens 308 and the eye 100 and the angle of rotation of the patient's head. In a further embodiment, the optical center of the multifocal lens 308 includes a mark 312, such as a crosshair mark, to identify the optical center of the multifocal lens 308, thereby making it easier to locate.

[0036] exist Figures 6A to 6D In another example depicted, the multifocal lens 608 includes a reflective coating 603 formed on its opposite sides. Thus, coating 603 replaces the function of powers 307 and 309, allowing light to pass through the multifocal lens 608 to create multiple focal points. Similar to multifocal lens 308, multifocal lens 608 can be attached to a non-patient device or trial frame during its use.

[0037] As previously described, according to certain embodiments, Figure 3A and Figure 3B A simplified schematic diagram of the multifocal lens 308 when used in conjunction with a non-patient device is shown. Figures 4A to 4C A simplified schematic top and side view of a multifocal lens 308 worn by a patient in a test frame 440 is shown. Figure 5 A flowchart illustrating a method 500 for determining the position 130 of a visual axis 120 using a visual axis recognition system 200 of FIG2, according to some embodiments, is shown. This visual axis recognition system may include a multifocal lens 308 coupled to a non-patient device or trial frame 440. Accordingly, for clarity, Figure 3A , Figure 3B and Figures 4A to 4C In this article, we will be with Figure 5 Let's describe it in more detail together.

[0038] Typically, at operation 510, when using the visual axis recognition system 200, the patient views through the multifocal lens 308 and focuses their line of sight onto a fixed beam 212. When the patient focuses their line of sight onto the fixed beam 212, a focal point F1 is formed on the fovea 122, where the patient's visual field center is located. A second focal power 209 of the multifocal lens 308 also creates a second focal point F2 near the retina 116 and along the optical axis 318 of the multifocal lens 308. Because the second focal power 209 of the multifocal lens 308, for example, having positive refractive power, increases the focusing (e.g., convergence) of light in the fixed beam 212, the focal point F2 has a different lateral position than the focal point F1 located on the retina 116.

[0039] like Figure 3A and Figure 4AAs depicted, when focal points F1 and F2 are not aligned along the visual axis 120 (e.g., not overlapping or laterally offset relative to each other), two isolated (e.g., misaligned, non-overlapping) images are formed on the patient's retina 116. In these cases, the patient sees two "spots" formed by the fixed beam 212: a first clear image created by focal point F1 and a second blurred (e.g., hazy or unclear) image created by focal point F2. However, as Figure 3B and Figure 4B As depicted, when focal points F1 and F2 overlap along visual axis 120, the patient can see two aligned (e.g., coincident, overlapping) images of a fixed beam 212 on the retina 116. In this context, image alignment, overlap, or coincidence refers to the alignment, overlap, or coincidence of the central spaces of the two images formed by focal points F1 and F2. This alignment occurs when the common optical center 314 of the powers 307 and 309 of the multifocal lenses 308 lies precisely on visual axis 120 of the eye 100.

[0040] Therefore, at operation 520, the multifocal lens 308 and / or the patient's head are moved to position the common optical center 314 of the multifocal lens 308 on the visual axis 120 of the eye 100. Figures 3A to 3B In the example shown, a multifocal lens 308 attached to a non-patient device can be moved relative to the patient's head along the X and Y axes while the patient continuously keeps their gaze on the fixed beam 212, so that focal point F2 is aligned with focal point F1 on visual axis 120. Alternatively, the multifocal lens 308 is stationary while the patient moves their head along the X and Y axes and continuously keeps their gaze on the fixed beam 212 in an attempt to align focal point F2 with focal point F1 or achieve visual overlap.

[0041] When focal point F2 is aligned with visual axis 120, the patient sees two overlapping images or spots in the central space. Even when aligned, the first image or spot formed by focal point F1 is sharp, while the second image or spot formed by focal point F2 is somewhat blurry. Figure 3B As shown, when focal point F2 overlaps with focal point F1 on visual axis 120, the line connecting the output point of fixed light source 202 (e.g., the origin of fixed beam 212) and the common optical center 314 of multifocal lens 308 intersects the anterior surface of cornea 104 (e.g., pupil plane) at the exact X / Y position of visual axis 120.

[0042] Now for reference Figures 4A to 4CIn one embodiment, instead of attaching the multifocal lens 308 to a non-patient device, the multifocal lens 308 is placed in a trial frame 440 worn by the patient. In this embodiment, the patient can move (e.g., rotate or tilt up, down, left, and right) their head 460 while wearing the trial frame 440 and continuously keeping their gaze on the fixed beam 212 in order to attempt to align or visually overlap the focal point F2 with the focal point F1 on the visual axis 120.

[0043] like Figure 4A As shown, when the patient focuses their gaze on the fixed beam 212, a first focal point F1 is formed on the fovea 122. Because the optical center 314 of the multifocal lens 308 is not aligned with the visual axis 120, the multifocal lens 308 forms a second focal point F2 in the ocular space of the eye 100 along an optical axis 318 that does not overlap with the visual axis 120. Figure 4B During this process, the patient moves or rotates their head 460 while focusing on the fixed beam 212, aligning the focal point F2 with the focal point F1 on the visual axis 120, thus seeing two images or spots that coincide in the central space formed by the fixed beam 212. As described above, when the focal point F2 overlaps with the focal point F1 on the visual axis 120, the line connecting the fixed light source 202 and the common optical center 314 of the multifocal lens 308 within the test frame 440 intersects the anterior surface of the cornea at position 130 on the visual axis 120.

[0044] For clarity, Figure 4C A schematic side view of a patient wearing the multifocal lens 308 when it is positioned within the test frame 440 is shown. While the patient maintains their gaze on the fixed beam 212, they rotate their head 460 in a "yes" (e.g., Y-rotation) or "no" (e.g., X-rotation) motion. Due to the distance between the patient's eye 100 and the multifocal lens 308, the rotational movement of the patient's head 460 creates a displacement of the multifocal lens 308 relative to the patient's eye 100 and the fixed beam 212. This displacement has a reference... Figure 3A and 3B The movement of the multifocal lens 308 described has the same effect. For example, if the distance between the eye 100 and the multifocal lens 308 is 12 mm, and the patient rotates their head by 5 degrees in an X or Y motion while keeping their line of sight on the fixed beam 212, then the multifocal lens 308 will therefore move (12 mm * tan(5°)) = 1.05 mm relative to the eye 100.

[0045] At operation 530, while the patient's head 460 and / or multifocal lens 308 are moving, imaging camera 204 captures images or videos of multifocal lens 308 and eye 100. Typically, imaging camera 204 captures images from the direction of a fixed beam 212 traveling toward eye 100. In some examples, recording video of eye 100 during method 500 can improve accuracy in identifying the position 130 of visual axis 120. The images or videos of multifocal lens 308 and eye 100 are then relayed to image processing system 206, which determines the position of eye 100 relative to the optical center 314 of multifocal lens 308 during the movement of the patient's head and / or multifocal lens 308. As described above, determining the X / Y position of eye 100 can be accomplished by utilizing the vascular system of the sclera of eye 100 as a landmark. In some examples, the optical center 314 is designated by a crosshair mark 312 on the multifocal lens 308 to be identified by the imaging camera 204 and / or the image processing system 206.

[0046] At operation 540, the patient's head and / or multifocal lens 308 continue to move until the patient reports seeing an overlapping image of the fixed light beam 212, such that the centers of two or more images coincide. Then, at operation 550, the image processing system 206 determines the position 130 of the patient's visual axis 120. Typically, when the patient sees two images aligned in the central space, the line connecting the output point of the fixed light source 202 to the optical center 314 of the multifocal lens 308 intersects the outer surface of the cornea 104 at the exact location of the visual axis 120, and therefore the position 130 of the visual axis 120 can be identified by locating this intersection.

[0047] In some embodiments, when a patient reports visual overlap of focal points F1 and F2, a single image of the eye 100 and multifocal lens 308 is acquired by imaging camera 204 and analyzed by image processing system 206. Therefore, the identification of the position 130 of visual axis 120 can be determined by a single X,Y coordinate. In other embodiments, while the patient attempts to maintain visual overlap of focal points F1 and F2, imaging camera 204 acquires video or a series of images, which are then analyzed by image processing system 206. The video or series of images can be acquired within any desired time period, such as 5 seconds, 10 seconds, 15 seconds, 20 seconds, 25 seconds, or any other suitable time period. For example, the time period can be between approximately 5 seconds and approximately 60 seconds, such as between approximately 5 seconds and approximately 30 seconds, such as between approximately 10 seconds and approximately 20 seconds. During this time period, the patient is instructed to try to maintain his / her gaze so that he / she sees the overlapping image of fixed beam 212. The image processing system 206 can then analyze the video or a series of images to determine the average X / Y position of the optical center 314 of the multifocal lens 308 relative to the eye 100, thus compensating for any unintentional eye and / or head movements of the patient when focused on the fixed beam 212. Accordingly, the identification of the position 130 of the visual axis 120 can be determined by the average X / Y coordinates.

[0048] In some embodiments, the fixed beam 212 may include two or more wavelengths or wavelength ranges with different reflective properties passing through the multifocal lens 308. In this embodiment, unwanted reflections of the fixed beam 212 toward the imaging camera 204 during the use of the visual axis recognition system 200 can be eliminated or significantly reduced. In one example, the fixed beam 212 may include a first wavelength having a first frequency to which the multifocal lens 308 is highly reflective and to which the imaging camera 204 is insensitive. The fixed beam 212 may also include a second wavelength having a second frequency, to which it has high transmittance through the multifocal lens 308 and to which the eye 100 is insensitive and the imaging camera 204 is sensitive. Therefore, the fixed beam 212 may be separated (e.g., filtered) by the multifocal lens 308 such that only the second wavelength of light is transmitted to the imaging camera 204. By separating the spectrum of the fixed beam 212 into two or more wavelengths to which the eye 100 and the imaging camera 204 have different sensitivities, the interference effect of the reflection from the multifocal lens 308 is reduced and the accuracy of the visual axis recognition system 200 in determining the position 130 of the visual axis 120 is improved.

[0049] Figures 6A to 6D A simplified schematic diagram of an alternative coated multifocal lens 608 that can be used in the visual axis recognition system 200 and method 500 according to some embodiments is shown. Figure 7A and Figure 7BAn image formed on a patient's retina 116 when using a coated multifocal lens 608 according to some embodiments is shown. Accordingly, for clarity, it will be described together herein. Figures 6A to 6D as well as Figure 7A and Figure 7B .

[0050] Figures 6A to 6D The coated multifocal lens 608 depicted herein is generally similar to the multifocal lenses 208 and 308 described above, but includes a coating 603 disposed on its two main surfaces 611a, 611b. The coating 603 is partially reflective and partially transmittive to the stationary beam 212. In some embodiments, the coating 603 enables spectral separation of the stationary beam 212 and the light entering the imaging camera 204. For example, the reflectance peak of the coating 603 (e.g., maximum reflectance) may correspond to the wavelength of the stationary beam 212 that the patient wants to see. In a further example, the coating 603 may have zero reflectance at the wavelength of the light to be detected by the imaging camera 204. Therefore, unwanted reflections of the stationary beam 212 toward the imaging camera 204 can be eliminated or significantly reduced by utilizing the coated multifocal lens 608, thereby enabling more accurate determination of the position 130 of the visual axis 120 during method 500.

[0051] The coating 603 on the coated multifocal lens 608 further enables the formation of two or more focal points depending on its reflectivity. Typically, the coating 603 can form an infinite number of focal points and images, with their intensity decreasing geometrically. However, the human eye 100 cannot perceive all of the images and therefore only a finite number. The number of perceptible or visible focal points formed can be controlled by modifying the reflectivity characteristics of the coating 603. For clarity, in Figures 6A to 6D Only four focal points F are depicted. L0 F L1 F L2 and F L3 When the fixed beam 212 passes through the coated multifocal lens 608 at a position other than the optical center 614, multiple focal points F L0 F L1 F L2 and F L3 Lateral offset from optical axis 618 (e.g.) Figure 6A and Figure 6C As shown), and the patient sees non-overlapping spots. However, when the fixed beam 212 is guided through the optical center 614 of the coated multifocal lens 608 and parallel to its optical axis 618 (as shown), Figure 6D As shown), focus F L0 F L1 F L2 and F L3Visual overlap occurs on the optical axis 618 of the coated multifocal lens 608, and the patient can see overlapping spots.

[0052] The multifocal lens 608 can be used to position the visual axis 120 of the patient's eye 100 via a method substantially similar to that described with reference to multifocal lenses 208 and 308 and method 500. Typically, the multifocal lens 608 moves laterally in the X or Y direction relative to the patient's eye 100 while the patient continuously focuses on the fixed beam 212. When the patient sees overlapping spots that coincide in the central space, the fixed beam 212 is guided through the optical center 614 of the multifocal lens 608, and the optical center 614 is located exactly on the visual axis 120 of the eye 100, thereby enabling the identification of the visual axis 120.

[0053] Figure 7A The image depicts a patient viewing a fixed beam 212 through a coated multifocal lens 608 at an off-center position. The focal point F... L0 F L1 F L2 and F L3 The image was misaligned on both the optical axis 618 and the visual axis 120. The patient saw a roughly linear line of spots 715, varying in size and clarity. Figure 7B This describes what a patient might see when a fixed beam of light 212 passes through the optical center 614 of a coated multifocal lens 608. Focus F L0 F L1 F L2 and F L3 The optical axis 618 and the visual axis 120 visually overlap each other. Compared with a lens that forms a single focal point, aligning with lenses that form two or more focal points during method 500 allows for more precise and accurate determination of the position of the visual axis 120.

[0054] The methods and apparatus described above provide a novel visual axis recognition system that can be used to improve the efficacy of ophthalmic procedures, such as presbyopia treatment, including corrective lens fitting, refractive surgery, intraocular lens implantation, and multifocal keratomileusis. The described visual axis recognition system can be further integrated with any suitable ophthalmic diagnostic device. Examples of suitable diagnostic devices include corneal topography, optical coherence tomography, wavefront meters (e.g., aberrometers), image-guided biometry, surgical microscopes, and other image-based diagnostic devices. In some examples, the visual axis recognition system 200 can be integrated with a device manufactured by Alcon in Fort Worth, Texas. INFINITI TM Verion TM ORA TM System LuxOR TMThe LX3 platform can be used in conjunction with other ophthalmic platforms. In some examples, the visual axis recognition system 200 can be used in conjunction with other ophthalmic platforms provided by other manufacturers.

[0055] Example Implementation

[0056] Example 1: A method for determining the position of the visual axis of a patient's eye, the method comprising: placing a multifocal optical lens near the patient's eye, the multifocal optical lens comprising two or more optical powers having corresponding spatially coincident optical centers at the optical center of the multifocal optical lens; generating a fixed light and directing it toward the patient's eye, the fixed light forming two or more images at a focal point near the retina of the patient's eye, the two or more images corresponding to the two or more optical powers of the multifocal optical lens; capturing images of the patient's eye and the multifocal optical lens along the direction of the fixed light; determining the X / Y position of the patient's eye relative to the optical center of the multifocal optical lens; moving the multifocal optical lens relative to the patient's eye while the patient maintains their gaze on the fixed light until the centers of the two or more images coincide in the patient's field of vision; and identifying the position of the patient's visual axis at the pupillary plane of the patient's eye, the position of the visual axis corresponding to the position of the optical center of the multifocal optical lens when viewed from the direction of the fixed light.

[0057] Example 2: The method as described in Example 1, wherein the multifocal optical lens is attached to the test frame worn by the patient.

[0058] Example 3: The method described in Example 1, wherein the multifocal optical lens is connected to a non-patient device.

[0059] Example 4: A system for determining the position of the visual axis of a patient's eye, the system comprising: a multifocal optical lens; a detector configured to track the movement of the eye, the detector further configured to capture an image of the multifocal optical lens relative to the position of the eye; and a processing system configured to identify the position of the visual axis of the eye at the anterior surface of the eye based on the image captured by the detector, wherein the visual axis of the eye corresponds to the optical center of the multifocal optical lens when the centers of two or more focal points of the multifocal optical lens coincide in the patient's field of vision.

[0060] Example 5: The system as described in Example 4, wherein the multifocal optical lens is attached to the test frame.

[0061] Example 6: The system as described in Example 4, wherein the multifocal optical lens is coupled to a non-patient device.

[0062] Example 7: The system as described in Example 4, wherein the detector is an infrared camera.

[0063] Example 8: The system as described in Example 7, wherein the infrared camera is configured to track eye movement by detecting signs of the vascular system in the sclera of the eye.

[0064] Example 9: The system as described in Example 4, wherein the multifocal optical lens includes an axial pyramid.

[0065] While the embodiments described above relate to this disclosure, other and further embodiments of this disclosure may be devised without departing from its essential scope, the scope of which is defined by the following claims.

Claims

1. A method for determining the position of the visual axis of a patient's eye, the method comprising: A multifocal optical lens is placed near the patient's eye. The multifocal optical lens includes two or more optical powers and has corresponding spatially coincident optical centers at its optical center. When using a visual axis recognition system, the multifocal optical lens is connected to a non-patient device, which includes an ophthalmic testing device. A fixed light is generated and directed toward the patient's eye, the fixed light forming two or more images at a focal point near the retina of the patient's eye, the two or more images corresponding to two or more optical powers of the multifocal optical lens; The patient's eye and the multifocal optical lens are captured along the direction of the fixed light; Determine the X / Y position of the patient's eye relative to the optical center of the multifocal optical lens; While the patient keeps their gaze on the fixed light, the multifocal optical lens is moved relative to the patient's eye by moving the non-patient device until the centers of the two or more images coincide in the patient's field of vision; and Identify the position of the visual axis of the patient's eye at the pupillary plane, and from the direction of the fixed light, the position of the visual axis corresponds to the position of the optical center of the multifocal optical lens.

2. The method as described in claim 1, wherein, The multifocal optical lens includes optical coatings on two or more of its surfaces.

3. The method as described in claim 2, wherein, The multifocal optical lens is configured to form more than two focal points within the patient's eye.

4. The method of claim 1, wherein, When the centers of the two or more images coincide with each other in the patient's field of vision, the position of the visual axis further corresponds to the position of the optical center of the multifocal optical lens.

5. The method of claim 1, wherein, The fixed light is spectrally separated into two or more wavelength ranges with different refractive indices and reflectivity by the multifocal optical lens.

6. The method of claim 1, wherein, The optical center of the multifocal optical lens is marked by a crosshair.

7. The method of claim 1, wherein, Identifying the position of the visual axis of the patient's eye further includes: During the period in which the patient keeps their gaze on the fixed light, the X / Y position of the optical center of the multifocal optical lens relative to the position of the patient's eye is spatially averaged, so that the patient sees an overlapping image formed by the fixed light.

8. The method of claim 7, wherein, The time period is between approximately 5 seconds and approximately 60 seconds.

9. The method of claim 1, wherein, The multifocal optical lens is a composite diffractive optical element configured to form an ultra-long focal length.

10. The method of claim 9, wherein, The multifocal optical lens includes an axial pyramid.

11. The method of claim 9, wherein, The multifocal optical lens includes an aspherical extended depth-of-focus lens.

12. A system for determining the position of the visual axis of a patient's eye, the system comprising: A multifocal optical lens, comprising two or more optical powers, having corresponding spatially coincident optical centers at the optical center of the multifocal optical lens, and being coupled to a patient device or a non-patient device, the patient device and the non-patient device being configured to provide displacement of the multifocal optical lens relative to the patient's eye. A fixed light source is used to generate fixed light and direct it toward the patient's eye, the fixed light forming two or more images at a focal point near the retina of the patient's eye, the two or more images corresponding to two or more optical powers of the multifocal optical lens; A detector configured to track the movement of the eye, the detector being further configured to capture an image of the multifocal optical lens relative to the position of the eye; as well as A processing system configured to identify the position of the visual axis of the eye at the anterior surface of the eye based on an image captured by the detector, wherein the visual axis of the eye corresponds to the optical center of the multifocal optical lens when the centers of two or more focal points of the multifocal optical lens overlap in the patient's field of vision to form an overlapping image.

13. The system of claim 12, wherein, The multifocal optical lens is a composite diffractive optical element configured to form an ultra-long focal length.

14. The system of claim 13, wherein, The multifocal optical lens includes an aspherical extended depth-of-focus lens.

15. The system of claim 12, wherein, The processing system is configured to identify the position of the visual axis of the eye, including that the processing system is configured to: During the period when the patient keeps their gaze on the fixed light, the X / Y position of the optical center of the multifocal optical lens relative to the position of the eye is averaged, so that the patient sees an overlapping image formed by the fixed light.

Images