Lens parameters for refining an eye model

Abstract

An ophthalmic system for generating an ocular model of an eye includes an optical coherence tomography (OCT) device, an aberrometer, and a computer. The OCT device detects OCT light reflected from the eye. The aberrometer detects aberrometer light reflected from the eye. The computer generates an ocular model of the eye from the reflected OCT light. The ocular model includes parameters describing the eye. The parameters include a lens parameter describing a lens of the eye. The computer determines an OCT-based wavefront from the ocular model, determines an aberrometer-based wavefront from the reflected aberrometer light, and compares the OCT-based wavefront to the aberrometer-based wavefront. If a difference between the wavefronts exceeds a predefined tolerance, the computer adjusts one or more values assigned to the parameters until the wavefronts satisfy the predefined tolerance. At least one adjusted value is assigned to the lens parameter.

Description

Technical Field

[0001] This disclosure generally relates to systems and methods for providing eye models, and more specifically to refining the lens parameters of the eye model. Background Technology

[0002] The natural lens is a complex optical device with two aspherical surfaces and a gradient refractive index. Adding to this complexity, the profile of the gradient refractive index can change with age. In a young lens, the refractive index gradually increases from the surface to the center. As we age, the refractive index distribution becomes more uniform in the central region of the lens, typically forming a plateau whose size increases with age. These changes in the refractive index distribution reduce both the lens's optical power and the contribution of the gradient to the lens's power.

[0003] Devices used to measure the axial dimension of the eye typically approximate the lens as having a single, uniform refractive index. However, this simplification can lead to errors in calculating eye size. For example, if the net refractive index along the path of light through the lens is higher (or lower) than assumed, the lens thickness in that region may be calculated as longer (or shorter) than it actually is. This, in turn, can degrade the accuracy of total axial length measurements and, for example, IOL (intraocular lens) diopter calculations. Summary of the Invention

[0004] In some embodiments, an ophthalmic system for generating an eye model of an eye includes an optical coherence tomography (OCT) device, an aberration meter, and a computer. The OCT device directs OCT light toward the eye and detects the OCT light reflected from the eye. The aberration meter directs aberration meter light toward the eye and detects the aberration meter light reflected from the eye. The computer generates an eye model of the eye based on the reflected OCT light. The eye model includes parameters describing the eye, where each parameter is assigned a value. These parameters include one or more lens parameters describing the lens of the eye. The computer determines an OCT-based wavefront based on the eye model, determines an aberration meter-based wavefront based on the reflected aberration meter light, and compares the OCT-based wavefront with the aberration meter-based wavefront. If the difference between the OCT-based wavefront and the aberration meter-based wavefront exceeds a predefined tolerance, the computer adjusts one or more values ​​assigned to one or more of these parameters until the OCT-based wavefront and the aberration meter-based wavefront meet the predefined tolerance. At least one adjusted value is assigned to a lens parameter.

[0005] The embodiment may exclude the following features or may include one, some or all of the following features: the lens parameter having the adjusted value describes the refractive index profile of the lens.

[0006] The computer adjusts one or more values ​​assigned to one or more parameters by repeating the following steps until the adjusted OCT-based wavefront and the aberration meter-based wavefront meet a predefined tolerance: adjusting the one or more values ​​to generate an adjusted eye model; determining the adjusted OCT-based wavefront based on the adjusted eye model; and comparing the adjusted OCT-based wavefront with the aberration meter-based wavefront to see if they meet the predefined tolerance.

[0007] The computer generates an eye model of the eye based on the reflected OCT light using a ray tracing program.

[0008] The computer generates an eye model based on reflected OCT light using the following steps: applying a ray tracing procedure; defining multiple rays passing through multiple anatomical interfaces of the eye; determining the positions of the anatomical interfaces based on the rays; and generating the eye model based on the positions of the anatomical interfaces. The computer can define the rays passing through each anatomical interface by repeating the following steps: determining the angle of refraction of the anatomical interface based on the refractive index and angle of incidence; and determining the distance to the next anatomical interface based on the reflected OCT light.

[0009] The system includes a topographic mapper that directs topographic mapper light toward the eye and detects the topographic mapper light reflected from the eye. A computer can generate an eye model of the eye by: determining a model-based anterior corneal surface from the eye model; determining a topographic mapper-based anterior corneal surface from the reflected topographic mapper light; and examining the eye model by comparing the model-based anterior corneal surface with the topographic mapper-based anterior corneal surface.

[0010] The computer generates an eye model of the eye by the following steps: examining the eye model by comparing it with one or more known measurements of the eye.

[0011] The computer determines the OCT-based wavefront using an eye model by applying a ray tracing program.

[0012] The computer compares an OCT-based wavefront with an aberration meter-based wavefront using the following steps: parameterizing the OCT-based wavefront with multiple wavefront parameters, each wavefront parameter being assigned to describe the OCT-based wavefront value; parameterizing the aberration meter-based wavefront with the same multiple wavefront parameters, each wavefront parameter being assigned to describe the aberration meter-based wavefront value; and comparing the OCT-based wavefront value with the aberration meter-based wavefront value.

[0013] The OCT device examines the eye model by directing the next OCT light toward the eye at an angle different from the OCT light and detecting the reflection of that next OCT light from the eye. The aberration meter examines the eye model by directing the next aberration meter light toward the eye at an angle different from the aberration meter light and detecting the reflection of that next aberration meter light from the eye. The computer examines the eye model by: generating a next eye model of the eye based on the reflected next OCT light; determining a next OCT-based wavefront based on this next eye model; and comparing this next OCT-based wavefront with the next aberration meter-based wavefront.

[0014] The computer determines the resulting eye model from the OCT-based wavefront-based eye model that meets predefined tolerances, and plans ophthalmic surgery based on the resulting eye model.

[0015] The computer determines the resulting eye model from an OCT-based wavefront-based eye model that satisfies a predefined tolerance, and generates a description of the lens's refractive index profile based on the resulting eye model.

[0016] In some embodiments, a method for generating an eye model of an eye includes: guiding OCT light toward the eye using an optical coherence tomography (OCT) device; detecting OCT light reflected from the eye using the OCT device; guiding aberration meter light toward the eye using an aberration meter; detecting aberration meter light reflected from the eye using the aberration meter; generating an eye model of the eye by a computer based on the reflected OCT light, the eye model including a plurality of parameters describing the eye, each parameter being assigned a value, the plurality of parameters including one or more lens parameters describing the lens of the eye; and generating an eye model of the eye by a computer based on the reflected OCT light. The eye model determines the OCT-based wavefront; the computer determines the aberration-based wavefront based on the reflected aberration meter light; the computer compares the OCT-based wavefront with the aberration-based wavefront; and if the difference between the OCT-based wavefront and the aberration-based wavefront exceeds a predefined tolerance, the computer adjusts one or more values ​​assigned to one or more of the plurality of parameters until the OCT-based wavefront and the aberration-based wavefront meet the predefined tolerance, and at least one adjusted value is assigned to the lens parameter among the one or more lens parameters.

[0017] The embodiments may exclude or include one, some, or all of the following features: The method adjusts one or more values ​​assigned to one or more parameters by repeating the following steps until the adjusted OCT-based wavefront and the aberration meter-based wavefront meet a predefined tolerance: adjusting the one or more values ​​to generate an adjusted eye model; determining the adjusted OCT-based wavefront based on the adjusted eye model; and comparing the adjusted OCT-based wavefront with the aberration meter-based wavefront to see if they meet the predefined tolerance.

[0018] This method generates an eye model of the eye based on reflected OCT light, including applying a ray tracing procedure through the following steps: defining multiple rays passing through multiple anatomical interfaces of the eye; determining the positions of the anatomical interfaces based on the rays; and generating an eye model based on the positions of the anatomical interfaces.

[0019] The method generates an eye model of the eye through the following steps: determining a model-based anterior corneal surface from the eye model; determining a topographic mapper-based anterior corneal surface from the topographic mapper; and examining the eye model by comparing the model-based anterior corneal surface with the topographic mapper-based anterior corneal surface.

[0020] This method compares an OCT-based wavefront with an aberration meter-based wavefront through the following steps: parameterizing the OCT-based wavefront with multiple wavefront parameters, each wavefront parameter being assigned to describe the OCT-based wavefront value; parameterizing the aberration meter-based wavefront with the same multiple wavefront parameters, each wavefront parameter being assigned to describe the aberration meter-based wavefront value; and comparing the OCT-based wavefront value with the aberration meter-based wavefront value.

[0021] The method further includes guiding a next OCT light toward the eye at an angle different from that of the OCT light by an OCT device; detecting the next OCT light reflected from the eye by the OCT device; guiding a next aberration meter light toward the eye at an angle different from that of the aberration meter light by an aberration meter; detecting the next aberration meter light reflected from the eye by the aberration meter; generating a next eye model of the eye by a computer based on the reflected next OCT light; determining a next OCT-based wavefront by the computer based on the next eye model; and comparing the next OCT-based wavefront with the next aberration meter-based wavefront by the computer.

[0022] In some embodiments, an ophthalmic system for generating an eye model of an eye includes an optical coherence tomography (OCT) device, an aberrometer, a topographic mapper, and a computer. The OCT device directs OCT light toward the eye and detects the OCT light reflected from the eye. The aberrometer directs aberrometer light toward the eye and detects the aberrometer light reflected from the eye. The topographic mapper directs topographic mapper light toward the eye and detects the topographic mapper light reflected from the eye. The computer generates an eye model of the eye based on the reflected OCT light. The eye model includes parameters describing the eye, where each parameter is assigned a value. These parameters include one or more lens parameters describing the lens of the eye. The eye model is generated by applying a ray tracing procedure that includes: defining multiple rays passing through multiple anatomical interfaces of the eye, wherein the rays are defined by repeating the following steps for each anatomical interface: determining the angle of refraction of the anatomical interface based on the refractive index and angle of incidence, and determining the distance to the next anatomical interface based on the reflected OCT light; determining the position of the anatomical interface based on the rays; and generating the eye model based on the position of the anatomical interface. The eye model is generated through the following steps: determining a model-based anterior corneal surface from the eye model, determining a topographically based anterior corneal surface from reflected topographically derived light, and verifying the eye model by comparing the model-based anterior corneal surface with the topographically derived anterior corneal surface. The eye model is also generated through the following steps: verifying the eye model by comparing it with one or more known measurements of the eye. The computer determines an OCT-based wavefront from the eye model by applying a ray tracing program, and determines an aberration-based wavefront from reflected aberration-derived light. The computer then compares the OCT-based wavefront with the aberration-derived wavefront. The OCT-based wavefront and the aberration meter-based wavefront are compared through the following steps: The OCT-based wavefront is parameterized using multiple wavefront parameters, each assigned to describe the OCT-based wavefront value; the aberration meter-based wavefront is parameterized using the same multiple wavefront parameters, each assigned to describe the aberration meter-based wavefront value; and the OCT-based wavefront value is compared with the aberration meter-based wavefront value. If the difference between the OCT-based wavefront and the aberration meter-based wavefront exceeds a predefined tolerance, the computer adjusts one or more values ​​assigned to one or more of the multiple parameters until the OCT-based wavefront and the aberration meter-based wavefront meet the predefined tolerance. At least one adjusted value is assigned to one of the one or more lens parameters, where the lens parameter with the adjusted value describes the refractive index profile of the lens.The one or more values ​​are adjusted by repeating the following steps until the adjusted OCT-based wavefront and the aberrometer-based wavefront meet a predefined tolerance: adjusting the one or more values ​​to generate an adjusted eye model; determining the adjusted OCT-based wavefront based on the adjusted eye model; and comparing the adjusted OCT-based wavefront with the aberrometer-based wavefront to see if they meet the predefined tolerance. The computer determines a resultant eye model from the eye model that generates an OCT-based wavefront that meets the predefined tolerance, plans ophthalmic surgery based on the resultant eye model, and generates a description of the lens's refractive index profile based on the resultant eye model. The OCT device further examines the eye model by guiding the next OCT light toward the eye at an angle different from the OCT light and detecting the reflection of that next OCT light from the eye. The aberrometer further examines the eye model by guiding the next aberrometer light toward the eye at an angle different from the aberrometer light and detecting the reflection of that next aberrometer light from the eye. The computer further examines the eye model through the following steps: generating a next eye model of the eye based on the reflected next OCT light, determining a next OCT-based wavefront based on the next eye model, and comparing the next OCT-based wavefront with the next aberration meter-based wavefront. Attached Figure Description

[0023] Figure 1 Examples of systems that provide an eye model according to certain embodiments are shown; Figure 2 An example of using an OCT device to measure the anterior surface of the cornea of ​​the eye is shown; Figure 3 An example of a topographic mapper measuring the anterior surface of the cornea of ​​the eye is shown; Figure 4 Examples of the interaction between OCT light and aberration meter light and the eye are shown; Figure 5A and Figure 5B An example of applying ray tracing procedures to determine the location of the eye's anatomical interfaces is shown; and Figure 6 It is shown that, according to certain embodiments, it can be made by Figure 1 This is an example of a method executed by the system to generate an eye model. Detailed Implementation

[0024] Example embodiments of the disclosed apparatus, systems, and methods are now shown in detail with reference to the specification and accompanying drawings. The specification and drawings are not intended to be exhaustive or otherwise limit the claims to the specific embodiments shown in the drawings and disclosed in the specification. Although the drawings illustrate possible embodiments, they are not necessarily drawn to scale, and certain features may be simplified, exaggerated, removed, or partially cut out to better illustrate the embodiments.

[0025] Embodiments of the disclosed systems and methods refine the lens parameters of the eye model, such as the refractive index profile of the lens, which can provide advantages. For example, they can produce more accurate dimensional readings, such as axial length and lens thickness. As another example, they can produce more anatomically accurate posterior lens topography, which can be useful for determining the size of the accommodative IOL and predicting the postoperative IOL position. Additionally, the refined lens parameters can produce information about presbyopia changes within the lens, which can be useful for determining refractive surgery strategies.

[0026] Figure 1 An example of a system 10 providing an eye model 12 according to certain embodiments is shown. In this example, system 10 includes a computer 20 (which includes logic 22, memory 24, and interface 26) coupled as shown, a measuring device 28, and an optical system 36. The measuring device 28 includes an optical coherence tomography (OCT) device 30, an aberration meter 32, and a topographic mapper 34 coupled as shown.

[0027] According to the operational example, computer 20 generates an eye model of eye 12 based on measurements from OCT device 30. The eye model includes lens parameters describing the lens of eye 12. Computer 20 determines an OCT-based wavefront from the eye model and an aberration-based wavefront from aberration meter 32. Computer 20 compares the OCT-based wavefront with the aberration-based wavefront. If the difference between these wavefronts exceeds a predefined tolerance, computer 20 adjusts at least one value assigned to the lens parameters.

[0028] Regarding the components of system 10, measuring device 28 includes an OCT device 30, an aberration meter 32, and a topographic mapper 34. The OCT device 30 directs OCT light toward the eye 12 and detects the OCT light reflected from various parts of the eye 12 to generate images of those parts. The OCT device 30 can be any suitable device that uses OCT to capture two-dimensional or three-dimensional images from an optically scattering medium (e.g., eye tissue). The OCT device 30 can use time-domain coding, frequency-domain coding, or other suitable spectral coding, and can use single-point scanning, parallel scanning, or other suitable scanning. (Reference) Figure 2 A more detailed example of the operation.

[0029] Figure 2An example of OCT device 30 measuring the anterior corneal surface 58 of eye 12 is shown. Typically, OCT device 30 detects light reflection from interfaces between media (e.g., between air and eye 12, or between different parts of eye 12, such as between the cornea and aqueous humor)). OCT device 30 records the optical path length of the detected light and converts the optical path length into a physical distance. In some embodiments, the raw data from OCT device 30 is converted such that the distance to the interface of eye 12 is expressed "as in air" (i.e., without considering the refractive index of the tissue).

[0030] In the example shown, the OCT device 30 detects light reflection from the anterior corneal surface 58, records the optical path length of the detected light, and represents the distance to the anterior corneal surface 58 as "as in air." The distances to different points on the surface 58 can be used to construct the surface 58 in the eye model. The OCT device 30 similarly measures the distances to interfaces between other parts of the eye 12 to construct the rest of the eye model.

[0031] refer to Figure 1 The aberration meter 32 directs aberration meter light toward the eye 12 and detects the aberration meter light reflected from the eye 12. The aberration meter 32 uses aberration measurement (i.e., wavefront technique) to measure how light passes through the eye 12 to reach the retina reflecting the light. Aberrations in the eye cause light to take on different shapes, which can be used to characterize aberrations. The aberration meter 32 generates a wavefront diagram (e.g., a Zernike coefficient diagram) based on the reflected light. A Hartmann-Shack aberration meter is an example of the aberration meter 32.

[0032] The reflective topographic mapper 34 directs topographic mapper light toward the eye and detects the topographic mapper light reflected from the eye to measure the shape of the anterior corneal surface 58. In some embodiments, measurements from the topographic mapper 34 and the OCT device 30 are used to construct the anterior corneal surface 58 of the eye model. (See reference...) Figure 3 A more detailed example of the operation.

[0033] Figure 3An example is shown of a topographic mapper 34 (e.g., a reflective topographic mapper) measuring the anterior corneal surface of eye 12. In this example, the topographic mapper 34 includes an illumination system 60 and a sensor 62. The illumination system 60 directs topographic mapper light toward the eye. The light projects a pattern (e.g., concentric rings or a grid of dots) onto the anterior corneal surface 58. The sensor 62 (e.g., a camera) detects the topographic mapper light reflected from the eye and generates an image of the reflected light. The image is analyzed to determine features of the eye, such as the shape of surface 58. If the surface is an ideal sphere, the reflected pattern matches the projected pattern. If aberrations exist on the surface, areas with closer spacing between reflected portions in the pattern (e.g., rings or dots) may indicate a steeper corneal curvature, while areas with farther spacing may indicate a flatter corneal curvature. The topographic mapper 34 may output results in the form of surface maps, such as axial maps, tangential maps, refractive power maps, or elevation maps.

[0034] Back Figure 1 The measuring device 28 can acquire measurements sequentially and / or simultaneously. To compare the measurements, they should be aligned. In some cases, features of the eye 12 (e.g., pupil or iris markings) can be used to align the measurements. In other cases, eye-tracking functionality can be used. In still other cases, the measuring device 28 can perform measurements along the same optical path, ensuring that the eye 12 has the same alignment for the measurements. (Reference) Figure 4 Describe an example of measuring device 28 performing measurements along the same optical path.

[0035] Figure 4 An example of the interaction between OCT light 54 and aberrometer light 56 ​​and eye 12 is illustrated. In this example, eye 12 includes ocular parts such as cornea 40, aqueous humor 42, iris 44, lens 46, vitreous fluid 50, and retina 52. In some embodiments, the interfaces between one or more surfaces of eye 12 and / or the various parts of the eye can be considered as anatomical interfaces that can be used to generate an eye model. For example, anatomical interfaces may include: the anterior surface of cornea 40; the interface between cornea 40, aqueous humor 42, iris 44, lens 46, vitreous fluid 50, and / or retina 52; and retina 52.

[0036] In this example, the beam of OCT light 54 enters the cornea 40, and the light from aberration meter light 56 ​​is reflected from the retina 52. If the eye 12 is an ideal emmetropic eye (without optical aberrations), then each ray of OCT light 54 has a reflected wavefront ray of aberration meter light 56 ​​that travels along the exact same optical path (only in opposite directions). If the eye 12 has optical aberrations, these aberrations cause the light from OCT light 54 and the light from aberration meter light 56 ​​from measuring device 28 to pass through the eye 12 along different paths. In the example shown, the beam of OCT light 54 is parallel. However, the beam of OCT light 54 can have any other suitable beam geometry, such as a single-scan OCT beam. As long as the beam geometry is known, the path of the beam of OCT light 54 can be determined.

[0037] return Figure 1 The optical system 36 includes one or more optical elements that guide light from the measuring device 28 toward the eye 12. The optical elements can act on (e.g., transmit, reflect, refract, diffract, collimate, adjust, shape, focus, modulate, and / or otherwise act on) the laser beam. Examples of optical elements include lenses, prisms, mirrors, diffractive optical elements (DOEs), holographic optical elements (HOEs), and spatial light modulators (SLMs).

[0038] Computer 20 controls the operation of system 10 to refine the lens parameters of the eye model. In some embodiments, computer 20 generates an eye model of eye 12 based on measurements from OCT device 30 and then determines an OCT-based wavefront from the eye model. Computer 20 compares the OCT-based wavefront with an aberration-based wavefront from aberration meter 32. If the comparison is unsatisfactory, computer 20 adjusts the lens parameter values ​​of the eye model and retests the adjusted eye model by comparing the OCT-based wavefront obtained from the adjusted eye model with the aberration-based wavefront until the comparison is satisfactory. In some embodiments, computer 20 may perform additional checks on the model.

[0039] Generate eye model: eye modelAn eye model may include parameters describing an eye 12, each of which is assigned a value. Parameters may describe characteristics of features of the eye 12 (e.g., a portion, such as the cornea of ​​the lens) (e.g., location, size, shape, and / or material properties such as refractive index). Parameters may describe, for example, the following characteristics of the eye 12 or a portion of the eye 12: (1) the wavefront of the eye 12; (2) the shape of a surface of a portion of the eye 12 (e.g., the anterior or posterior surface of the cornea or the surface of the lens); (3) distances through the portions of the eye 12 or between these portions (e.g., the distance between the posterior cornea and the anterior lens, the distance between the posterior lens and the retina, or the distance through the cornea, lens, vitreous humor, or aqueous humor); and the refractive index of a portion of the eye 12. The value assigned to a parameter gives a specific value for that parameter, such as the specific thickness of the cornea. As an example, lens parameters describe characteristics of the lens, such as the refractive index profile of the lens. In this example, the refractive index profile may describe the refractive index at a specific location of the lens.

[0040] The parameter values ​​are constrained. Constraints can be harder constraints with higher priority to be satisfied, or softer constraints with lower priority to be satisfied. In some examples, the following parameter values ​​may be deterministic and are considered harder constraints: (1) The whole eye :Wavefront; (2) cornea : the shape of the front and rear surfaces, the physical and optical distances traversed, and the refractive index; (3) Aqueous humor : Physical distance and refractive index; (4) lens : The shape of the anterior surface of the lens, the length of the light path, and the general refractive index profile (but without specific values); (5) vitreous body : Physical distance and refractive index. In this example, the following parameter values ​​may be uncertain and are considered variables or soft constraints: (1) lens (2) The shape of the posterior surface of the lens, the physical path it takes, and the specific value of its refractive index profile; vitreous body : The direction through which the light beam passes; (3) retina Location, surface shape.

[0041] Generative eye model: Ray tracingComputer 20 can generate an eye model in any suitable manner based on the reflected OCT light. In some embodiments, computer 20 applies a ray tracing procedure to generate the eye model. Ray tracing determines the path of light through eye 12, including how the interfaces between the various parts of eye 12 refract the light. At tissue boundaries, refraction is calculated according to Snell's Law, which states that the ratio of the sine of the incident angle θ to the sine of the refraction angle θ is equal to the reciprocal of the ratio of the refractive indices n: sin θ2 / sin θ1 = n1 / n2. Light rays passing through the parts of eye 12 with a uniform refractive index propagate in a constant direction, while light rays propagating in the parts with a gradient refractive index propagate in a curved path. As the light passes through eye 12, the process calculates the points of intersection between the light rays and the surfaces, and calculates the surface normals at those points to determine the new direction of the light rays according to Snell's Law. These points and the surface normals at these points can be used to determine the shape of the surfaces. Reference Figure 5A and Figure 5B Examples describing such a process.

[0042] Figure 5A and Figure 5B An example is shown of applying a ray tracing procedure to determine the location of the anatomical interface 57 of the eye 12 in order to generate an eye model. Figure 5A Anatomical interfaces 57 are shown, including: interface 57a (anterior corneal surface 58); interface 57b (anterior lens surface) between aqueous humor 42 and lens 46; interface 57c (posterior lens surface) between lens 46 and vitreous fluid 50; and interface 57d (surface of retina 52). Distance d' represents the physical distance to anatomical interfaces 57.

[0043] Figure 5B Measurements from OCT device 30 are shown, recording the distance d, measured "as if in air," of the OCT light propagating to the point at anatomical interface 57. The light travels through air to reach interface 57a, therefore the distance d1 = d'1. However, the light travels through the eye tissue to reach interfaces 57b through 57d, which reduces this distance, making d'1 = d'1. i < d i , where i = b, c and d.

[0044] According to the operational example, computer 20 defines the light rays passing through the anatomical interfaces of eye 12, determines the position of the anatomical interfaces based on the light rays, and generates an eye model using the position of the anatomical interfaces. Computer 20 defines the light rays by repeating the following steps for each anatomical interface: determining the angle of refraction of the anatomical interface using the refractive index and angle of incidence of the tissue; and determining the distance to the next anatomical interface based on OCT measurements.

[0045] In this example, the OCT device 30 provides initial "air" distances d to various points on the anatomical interface 57. In some embodiments, the topographic mapper 34 may provide additional measurements of the shape of the interface 57a (anterior corneal surface 58). Additionally, uncertain parameter values ​​may be assigned initial values, which may be adjusted in response to additional information. For example, the refractive index profile of the lens may be initially parameterized, for example, expressed as parameters, where initial values ​​are assigned. Initial values ​​may be, for example, the average of a population.

[0046] Starting from interface 57a (anterior corneal surface 58), the OCT device 30 provides distances d1 = d'1 to each point on interface 57a. The distances d'2 to each point on interface 57b (anterior lens surface) can be calculated based on the distances d2 to these points and the refractive index of the aqueous humor. The angle of refraction at each point on interface 57b can be calculated based on the shape of the anterior lens surface, the direction of light rays, the refractive index of the aqueous humor, and the initial values ​​of the lens refractive index at these points. The distances d' to the remaining interfaces 57c and 57d can be calculated in a similar manner.

[0047] Computer 20 constructs an eye model based on the length and position of light rays. The points where light rays intersect with the anatomical interface 57 and the surface normals at these points can be used to determine the shape of the anatomical interface 57. In some embodiments, computer 20 constructs the eye model by modifying an existing model. In other embodiments, computer 20 constructs the eye model from raw data.

[0048] In some cases, computer 20 may take into account additional aspects of eye 12 when generating the eye model. These additional aspects may be found, for example, in the medical history of eye 12. Examples of such consideration include the refractive index of the IOL in patients with intraocular lenses, the atypical corneal refractive index of previously cross-linked corneas, and the atypical corneal surface of keratoconus.

[0049] Generate an eye model: Inspect the model In some embodiments, computer 20 can examine the eye model by comparing one or more parameter values ​​of the eye model with other measurements of eye 12 (e.g., measurements from measurement device 28 of system 10 or measurements outside system 10). Significant deviations between values ​​can indicate a problem. A significant deviation can be, for example, a deviation beyond one or two standard deviations, or greater than a specified percentage, such as 2% or 5%. Examples of problems include issues with measurement conditions (e.g., insufficient sampling, inadequate patient fixation, and / or tear film instability), measurement device 28 (e.g., device alignment and / or calibration), or parameters of the model (e.g., lens topography parameters). In some cases, the deviation may have specific characteristics indicating a possible problem.

[0050] Computer 20 can respond to the detected deviation in any suitable manner. For example, computer 20 can send a notification identifying one or more related problems (e.g., one or more problems that are the cause of the deviation or may be the cause of the deviation). As another example, computer 20 can provide a suggestion to re-measure with one or more measuring devices 28 associated with the deviation, for example, which may be the cause of the deviation. As yet another example, computer 20 can (e.g., from the medical history of eye 12) identify the condition of eye 12 and notify the user of these conditions, which provide context for the deviation.

[0051] Comparison of anterior corneal surface In some embodiments, computer 20 may compare values ​​describing the anterior corneal surface 58 of an eye model with other descriptive values ​​from the anterior corneal surface 58 (e.g., toric diopter or measurements of the anterior corneal surface 58 as measured by topography 34). Significant discrepancies may indicate problems such as undersampling and / or inadequate device issues with surface 58 (e.g., inadequate device alignment or calibration). For example, computer 20 may determine that measurements of surface 58 from OCT device 30 and / or topography 34 are insufficient, or that measurements from OCT device 30 and / or topography 34 are not aligned with other measurements. Computer 20 may send notifications identifying problems or potential problems and / or recommendations to re-measure using one or more measuring devices 28 (e.g., OCT device 30 and / or topography 34) that may be causing the discrepancy.

[0052] Determine the wavefront The wavefront of the eye is typically measured at the corneal surface or entrance pupil plane. However, the wavefront can be calculated at any suitable location (e.g., the anterior surface of the lens) using aberration measurements and / or anatomical OCT data. Computer 20 can determine the OCT-based wavefront in any suitable manner based on an eye model. In some embodiments, computer 20 determines the OCT-based wavefront by applying a ray-tracing procedure to the eye model. Light rays originating from a point on the retina propagate through the eye 12, similar to... Figure 5A As shown, but in the opposite direction. Computer 20 obtains the position and orientation of the light rays at the selected location and constructs an OCT-based wavefront from that position and orientation. Computer 20 determines the aberration-based wavefront based on the reflected aberration-meter light from aberration meter 32. In some embodiments, aberration meter 32 generates a wavefront map, and computer 20 determines the aberration-based wavefront based on that map.

[0053] Comparison of wavefrontsComputer 20 can compare OCT-based wavefronts with aberration meter-based wavefronts in any suitable manner. In some embodiments, the computer compares the wavefronts to see if their differences exceed a predefined tolerance. The predefined tolerance can be defined as a known error tolerance adapted to measurement device 28. For example, the predefined tolerance could be the largest of known error tolerances.

[0054] Wavefronts can be parameterized using the same parameters, and computer 20 can compare wavefronts by comparing the values ​​of these parameters. According to an example of operation, computer 20 parameterizes an OCT-based wavefront with parameters, where each parameter is assigned to describe the OCT-based value of the OCT-based wavefront. Computer 20 then parameterizes an aberration-based wavefront with these parameters, where each parameter is assigned to describe the aberration-based value of the aberration-based wavefront. Computer 20 then compares the OCT-based values ​​with the aberration-based values.

[0055] Typically, comparing more parameter values ​​can increase the time required for the comparison. Therefore, the number of parameters to be compared can be chosen based on the desired efficiency. In some embodiments, computer 20 can perform a faster comparison that compares fewer parameter values ​​in order to identify major defects in the eye model that can be addressed before performing a more extensive (but slower) comparison that compares more parameter values.

[0056] Based on the example of rapid comparison, computer 20 can examine an eye model by generating a less detailed simulated wavefront. For example, computer 20 can determine the toric representation of anatomical interface 57 and then calculate the spherical and cylindrical parameters of the wavefront simulated through anatomical interface 57. The parameters of the simulated wavefront can be compared with the spherical and cylindrical parameters of the wavefront based on an aberrometer. Significant deviations can indicate problems, such as inaccurate axial length measurements, inadequate patient fixation, and / or inadequate device alignment or calibration. Computer 20 can send notifications identifying problems or potential problems and / or suggestions to re-measure using one or more measuring devices 28 (e.g., OCT device 30 and / or aberrometer 32) that may be causing the deviation.

[0057] According to another example of faster comparison, computer 20 can check whether the parameters of the simulated wavefront conform to, for example, measurements from topographic mapper 34. For instance, computer 20 can compare the anterior corneal surface 58 of the eye model with the surface 58 measured by topographic mapper 34. In this example, computer 20 determines the model-based anterior corneal surface from the eye model and the topographic mapper-based anterior corneal surface from the topographic mapper 34. Computer 20 checks the eye model by comparing the model-based anterior corneal surface with the topographic mapper-based anterior corneal surface. Significant discrepancies can indicate problems such as tear film instability and / or inadequate device alignment or calibration. Computer 20 can send notifications identifying problems or potential problems and / or suggestions to re-measure using one or more measuring devices 28 (e.g., OCT device 30 and / or topographic mapper 34) that may be causing the discrepancy.

[0058] According to an example of a broader comparison, computer 20 utilizes a wavefront diagram (e.g., a Zernike coefficient diagram) that includes wavefront parameters. In this example, computer 20 examines the OCT-based wavefront value against the aberration-based wavefront value. For example, the slope of the aberration-based wavefront can be compared to the slope of light rays leaving the eye based on an OCT-based model. Any appropriate number (e.g., 20 to 50, 50 to 100, or more than 100) of the harmonic OCT-based and aberration-based values ​​(e.g., slope) can be examined. The number of values ​​can be adjusted according to desired completeness and / or efficiency. Significant deviations in higher-order Zernike parameterization can indicate problems such as tear film instability, inaccurate lens topography parameters, inadequate patient fixation, and / or inadequate device alignment or calibration. Computer 20 can send notifications identifying problems or potential problems and / or suggestions to re-measure using one or more measurement devices 28 (e.g., OCT device 30 and / or aberration meter 32) that may be causing the deviation.

[0059] Adjust parameter values If the difference between the OCT-based wavefront and the aberration meter-based wavefront exceeds a predefined tolerance, computer 20 adjusts one or more parameter values ​​(such as lens parameter values) of the OCT-based wavefront until the wavefront comparison meets the predefined tolerance. Computer 20 adjusts these values ​​by repeating the following steps: adjusting the values ​​to generate an adjusted eye model; determining the adjusted OCT-based wavefront based on the adjusted eye model; and comparing the adjusted OCT-based wavefront with the aberration meter-based wavefront to see if they meet the predefined tolerance.

[0060] Computer 20 can adjust parameter values ​​in any suitable manner. In some embodiments, less certain values ​​are adjusted before being compared to more certain values. Less certain values ​​may include values ​​that are not directly measured (e.g., lens refractive index or cataract grading), values ​​from less reliable measuring devices 28, or values ​​given by softer constraints. More reliable values ​​may include values ​​supported by multiple measurements, values ​​generally known in the field, or values ​​given by harder constraints.

[0061] Perform another check In some embodiments, system 10 performs another check on the eye model. In these embodiments, measuring device 28 measures eye 12 from an angle different from the angle previously used to measure eye 12, and the measurements are compared. For example, measuring device 28 may first measure the eye "on-axis," i.e., the optical axis of measuring device 28 is aligned with the axis of eye 12 (e.g., visual or optical). To check the eye model, measuring device 28 may measure the eye "off-axis," i.e., the axis of measuring device 28 forms an angle with the axis of eye. This angle may be, for example, 0 to 10 degrees and / or 10 to 20 degrees, such as approximately 3 degrees. Computer 20 uses the measurements from the different angles to generate new wavefronts for comparison in order to check the eye model.

[0062] For example, OCT device 30 directs OCT light toward the eye at different angles and detects the OCT light reflected from the eye. Aberrometer 32 directs aberrometer light toward the eye at different angles, detects the aberrometer light reflected from the eye, and generates an aberrometer-based wavefront. Computer 20 generates another eye model of the eye based on the reflected OCT light and determines an OCT-based wavefront from this eye model. Computer 20 then compares these wavefronts to examine the eye model.

[0063] Computer 20 stores the resulting eye model in memory 24 and can output the model via interface 26. In some embodiments, computer 20 uses the resulting eye model to plan ophthalmic surgeries, such as cataract or refractive surgeries. For example, the model can be used to determine the size of an accommodative intraocular lens (IOL) or predict the postoperative position of the IOL. In other embodiments, computer 20 generates a refractive index profile of the lens from the resulting eye model. This profile can be used, for example, to detect presbyopia changes in the lens, which can be used to determine a refractive surgery strategy.

[0064] Figure 6 It is shown that, according to certain embodiments, it can be made by Figure 1 This is an example of a method for generating an eye model executed by system 10. In some embodiments, computer 20 can execute the steps of the method by sending instructions to components of system 10.

[0065] The method begins at step 110, where the OCT device 30 directs a beam of OCT light toward tissue of the eye that reflects the light. At step 112, the OCT device 30 detects the reflected OCT light. At step 114, the aberration meter 32 directs an aberration meter beam toward the tissue, and at step 116 detects the aberration meter light reflected from the tissue.

[0066] At step 120, computer 20 generates an eye model of the eye based on the reflected OCT light. In some embodiments, computer 20 generates the eye model by applying a ray tracing procedure through the following steps: defining the light rays passing through the anatomical interfaces of the eye; determining the position of the anatomical interfaces based on the light rays; and generating the eye model based on the position of the anatomical interfaces. The light rays passing through the anatomical interfaces can be defined by repeating the following steps for each anatomical interface: determining the angle of refraction of the anatomical interface based on the refractive index and the angle of incidence; and determining the distance to the next anatomical interface based on the reflected OCT light.

[0067] Some embodiments may include generating variations of the eye model. For example, computer 20 may construct the anterior corneal surface of the eye model based on measurements from OCT device 30 and topographic mapper 34. As another example, computer 20 may examine the eye model by comparing it with other measurements of the eye, such as toposcopic measurements.

[0068] At step 122, computer 20 determines an OCT-based wavefront based on an eye model. Computer 20 may apply a ray tracing process to calculate the OCT-based wavefront. At step 124, computer 20 determines an aberration-based wavefront based on reflected aberration meter light. In some embodiments, aberration meter 32 generates a wavefront map and provides this map to computer 20.

[0069] At step 128, computer 20 compares the OCT-based wavefront with the aberration meter-based wavefront. Computer 20 can compare the wavefronts by: parameterizing the OCT-based wavefront with wavefront parameters, each parameter being assigned to describe the OCT-based wavefront value; parameterizing the aberration meter-based wavefront with these wavefront parameters, each parameter being assigned to describe the aberration meter-based wavefront value; and comparing the OCT-based wavefront value with the aberration meter-based wavefront value.

[0070] The wavefront can be matched within a predefined tolerance at step 130. If the wavefront does not match at step 130, the computer 20 adjusts one or more parameter values ​​at step 132 to generate an adjusted eye model. The method then proceeds to step 134 to determine an OCT-based wavefront from the adjusted eye model. The method then returns to step 128 to compare the adjusted OCT-based wavefront with an aberration meter-based wavefront.

[0071] If wavefront matching occurs at step 130, the method proceeds to step 140, where computer 20 examines the eye model. To examine the model, measuring devices 30 (e.g., OCT device 30 and aberration meter 32) measure the eye 12 from different angles. Computer 20 generates the next wavefront based on the new measurements for comparison to examine the eye model.

[0072] At step 142, the eye model may pass the check. If the eye model passes, the method proceeds to step 146, where computer 20 provides the results. Computer 20 may display and / or use the results in any suitable manner. For example, these results may be used to plan ophthalmic surgery (e.g., cataract or refractive surgery) or to generate a description of the refractive index profile of the lens. The method then ends.

[0073] Components of the systems and apparatus disclosed herein (such as computer 20) may include interfaces, logic, and / or memory, any of which may include computer hardware and / or software. Interfaces may receive input to and / or send output from components and are generally used to exchange information between, for example, software, hardware, peripheral devices, users, and / or other external entities. Users may use interfaces such as graphical user interfaces (GUIs) or interface devices to interact with the computer (e.g., provide input and / or receive output). Examples of interface devices include input and / or output devices such as keyboards, mice, touchpads, touchscreens, microphones, displays, foot pedals, gesture sensors, and / or speakers.

[0074] Logic can perform operations on components. Logic may include one or more electronic devices that process data (e.g., execute instructions to generate outputs from inputs). Examples of such electronic devices include computers, processors, microprocessors (e.g., central processing units (CPUs)), and computer chips. Logic may include computer software that encodes instructions that can be executed by electronic devices to perform operations. Examples of computer software include computer programs, applications, and operating systems.

[0075] Memory can store information and may include tangible, computer-readable, and / or computer-executable storage media. Examples of memory include computer memory (e.g., random access memory (RAM) or read-only memory (ROM)), mass storage media (e.g., hard disk), removable storage media (e.g., optical disc (CD) or digital video or universal disc (DVD)), databases, network storage devices (e.g., servers), and / or other computer-readable media. Specific embodiments may be directed to memory encoded with computer software.

[0076] Although this disclosure has been described with reference to certain embodiments, modifications to the embodiments (such as alterations, substitutions, additions, omissions, and / or other modifications) will be apparent to those skilled in the art. Therefore, modifications can be made to the embodiments without departing from the scope of the invention. For example, modifications can be made to the systems and apparatus disclosed herein. Components of the systems and apparatus may be integral or separate, or the operation of the systems and apparatus may be performed by more, fewer, or other components, as will be apparent to those skilled in the art. As another example, modifications can be made to the methods disclosed herein. These methods may include more, fewer, or other steps, and these steps may be performed in any suitable order, as will be apparent to those skilled in the art.

Claims

1. An ophthalmic system for generating an eye model, the system comprising: An optical coherence tomography (OCT) device, wherein the OCT device is configured to: Guide the OCT light toward the eye; as well as Detecting OCT light reflected from the eye; Aberration meter, the aberration meter being configured to: Directing the aberration meter light toward the eye; and Detecting aberration light reflected from the eye; as well as Computer, the computer is configured to: The eye model of the eye is generated based on reflected OCT light, wherein the computer applies a ray tracing program to generate the eye model, the eye model including multiple parameters describing the eye, each parameter being assigned a value, the multiple parameters including one or more lens parameters describing the lens of the eye; The wavefront based on OCT is determined according to the eye model; The wavefront based on the aberration meter is determined by the reflected aberration meter light; The wavefront based on OCT is compared with the wavefront based on aberration meter. as well as If the difference between the OCT-based wavefront and the aberration meter-based wavefront exceeds a predefined tolerance, one or more values ​​of one or more of the plurality of parameters are adjusted until the OCT-based wavefront and the aberration meter-based wavefront meet the predefined tolerance, and at least one adjusted value is assigned to a lens parameter among the one or more lens parameters; wherein the lens parameter having the adjusted value describes the refractive index profile of the lens.

2. The ophthalmic system as claimed in claim 1, wherein, The computer is configured to adjust one or more values ​​assigned to one or more parameters by the following steps: Repeat the following steps until the adjusted OCT-based wavefront and the aberration meter-based wavefront meet the predefined tolerance: Adjust one or more of the values ​​to produce the adjusted eye model; The adjusted OCT-based wavefront is determined based on the adjusted eye model; as well as The adjusted OCT-based wavefront is compared with the aberration meter-based wavefront to see if they meet the predefined tolerance.

3. The ophthalmic system as claimed in claim 1, wherein, The computer is configured to generate the eye model of the eye based on the reflected OCT light through the following steps: Apply ray tracing using the following steps: Define multiple light rays that pass through multiple anatomical interfaces of the eye; The location of the anatomical interface is determined based on the light; and The eye model is generated based on the location of the anatomical interface.

4. The ophthalmic system as described in claim 3, wherein, The computer is configured to define a ray among the plurality of rays passing through the anatomical interface by the following steps: Repeat the following steps for each anatomical interface: The angle of refraction of the anatomical interface is determined based on the refractive index and the angle of incidence; and The distance to the next anatomical interface is determined based on the reflected OCT light.

5. The ophthalmic system of claim 1, further comprising a topographic mapper, the topographic mapper being configured to: Guide the topographic map light toward the eye; and Detect topographic light reflected from the eye.

6. The ophthalmic system of claim 5, wherein the computer is configured to generate the eye model of the eye by means of the following steps: The model-based anterior corneal surface is determined from the eye model; The anterior corneal surface is determined from reflected topographic light; as well as The eye model is examined by comparing the model-based anterior corneal surface with the topographic mapper-based anterior corneal surface.

7. The ophthalmic system of claim 1, wherein the computer is configured to generate the eye model of the eye by means of the following steps: The eye model is examined by comparing it with one or more known measurements of the eye.

8. The ophthalmic system of claim 1, wherein the computer is configured to determine an OCT-based wavefront based on the eye model through the following steps: Apply ray tracing.

9. The ophthalmic system of claim 1, wherein the computer is configured to compare the OCT-based wavefront with the aberration meter-based wavefront by the following steps: The OCT-based wavefront is parameterized using multiple wavefront parameters, each of which is assigned to describe the OCT-based wavefront value of the OCT-based wavefront. The aberration-based wavefront is parameterized using the plurality of wavefront parameters, each wavefront parameter being assigned a wavefront value based on the aberration-based wavefront that describes the aberration-based wavefront. as well as The wavefront value based on OCT is compared with the wavefront value based on aberration meter.

10. The ophthalmic system as claimed in claim 1: The OCT device is further configured to examine the eye model through the following steps: Guide the next OCT light toward the eye at an angle different from the angle of the OCT light; and Detect the next OCT light reflected from the eye; and The aberration meter is further configured to examine the eye model through the following steps: Guide the next aberration meter light toward the eye at an angle different from the angle of the aberration meter light; and Detect the next aberration meter light reflected from the eye; and The computer is further configured to examine the eye model through the following steps: The next eye model of the eye is generated based on the reflected next OCT light; The next OCT-based wavefront is determined based on the next eye model; and The next OCT-based wavefront is compared with the next aberration meter-based wavefront.

11. The ophthalmic system of claim 1, wherein the computer is further configured to: The resulting eye model is determined from the eye model that generates the OCT-based wavefront satisfying the predefined tolerance; and Based on the results, an eye model is used to plan ophthalmic surgery.

12. The ophthalmic system of claim 1, wherein the computer is further configured to: The resulting eye model is determined from the eye model that generates the OCT-based wavefront satisfying the predefined tolerance; and Based on the results, the eye model generates a description of the refractive index profile of the lens.

13. A method for generating an eye model, the method comprising: The OCT light is guided toward the eye using an optical coherence tomography (OCT) device; The OCT device detects the OCT light reflected from the eye; The aberration meter light is directed toward the eye via the aberration meter; The aberration meter detects the aberration meter light reflected from the eye; The eye model of the eye is generated by a computer based on reflected OCT light, wherein the computer applies a ray tracing program to generate the eye model, the eye model including multiple parameters describing the eye, each parameter being assigned a value, the multiple parameters including one or more lens parameters describing the lens of the eye; The computer determines the OCT-based wavefront based on the eye model; The computer determines the aberration-based wavefront based on the reflected aberration meter light; The computer compares the OCT-based wavefront with the aberration meter-based wavefront. as well as If the difference between the OCT-based wavefront and the aberration meter-based wavefront exceeds a predefined tolerance, the computer adjusts one or more values ​​assigned to one or more of the plurality of parameters until the OCT-based wavefront and the aberration meter-based wavefront meet the predefined tolerance, and at least one adjusted value is assigned to a lens parameter among the one or more lens parameters; wherein the lens parameter having the adjusted value describes the refractive index profile of the lens.

14. The method of claim 13, wherein adjusting one or more values ​​assigned to one or more parameters comprises: Repeat the following steps until the adjusted OCT-based wavefront and the aberration meter-based wavefront meet the predefined tolerance: Adjust one or more of the values ​​to produce the adjusted eye model; The adjusted OCT-based wavefront is determined based on the adjusted eye model; as well as The adjusted OCT-based wavefront is compared with the aberration meter-based wavefront to see if they meet the predefined tolerance.

Images