Automated assessment of human lens capsule stability

Abstract

A method for assessing a lens capsule stability condition in an eye of a human patient includes simultaneously directing electromagnetic energy in a predetermined spectrum via an energy source onto a pupil of the eye after movement of the eye results in eye saccades occurring therein. The method further includes acquiring images of the eye indicative of the eye saccades using an image capture device and calculating a motion profile of the lens capsule using the images via an ECU. Additionally, the method includes extracting time-normalized lens capsule oscillation trajectories based on the motion profile via the ECU and then model fitting the lens capsule oscillation trajectories via the ECU, thereby assessing the lens capsule instability condition. Also disclosed herein is an automated system for performing an embodiment of the method, the automated system including an energy source, an image capture device, and an ECU.

Description

Background Technology

[0001] This disclosure relates to automated methods and systems for non-invasively diagnosing or assessing potential lens capsule stability within the eye of a human patient. A non-limiting example of lens stability condition that can be effectively diagnosed according to this teaching is suspensory ligament insufficiency (ZI). Furthermore, the solutions described herein can be tailored, for example, during preoperative fitting, in determining optimal cataract surgery planning, or in assessing candidates for accommodative intraocular lens (aIOL) devices when evaluating a patient's accommodative potential. Similarly, other preoperative, postoperative, diagnostic, or therapeutic procedures related to lens capsule stability or general eye health can benefit from this teaching.

[0002] The lens of the human eye comprises the lens capsule, epithelium, and supporting fibers. The lens capsule is primarily a thin, transparent membrane, its periphery firmly attached to an elastic fibrous ring, referred to in the art as Zinn's membrane / zonules of Zinn, or simply the suspensory ligaments. During accommodation, the ciliary muscles within the eye contract and relax in conjunction with the suspensory ligaments, which alters the shape of the lens capsule. Therefore, the suspensory ligaments contribute to normal eye function by fixing the lens capsule along the optical axis while appropriately modulating the various forces exerted on the lens by the ciliary muscles.

[0003] The aforementioned ZI condition occurs when the suspensory ligaments are excessively elastic or "soft." Consequently, the attachment of the lens and capsular bag to the ciliary muscle may become less secure. Therefore, patients diagnosed with ZI may have an increased risk of certain complications during cataract surgery, lens replacement, or aIOL device implantation. Surgeons performing surgery on patients with ZI may attempt to mitigate surgical risks by using capsular support devices to stabilize the capsular bag, performing laser-based capsulorhexis, or taking other preventative measures.

[0004] The size of the suspensory ligaments is on the order of tens of micrometers. The extremely small size and completely obscured location of the suspensory ligaments behind the iris hinder effective direct optical examination of their structural integrity. Therefore, the presence of ZI in a given patient is often revealed indirectly, for example using slit-lamp examination, during which the surgeon applies stimulation to the patient's body to elicit eye movements. For example, the clinician may tap the headrest supporting the patient's head to apply manual stimulation, or may gently tap the side of the patient's head directly. Ultrasonic stimulation can be used as an alternative method.

[0005] Both methods can lead to increased patient anxiety because patients can anticipate the stimulus. In particular, ultrasound stimulation typically requires direct contact between the ultrasound measuring device and the patient's eye. Furthermore, diagnostic results are often highly skill-dependent and subjective. Therefore, underlying ZI conditions or other lens capsule instabilities may be unexpectedly discovered, for example, during eye surgery, which could adversely affect the surgical outcome or necessitate changes to the surgical plan. Summary of the Invention

[0006] This article discloses methods and systems for performing automated assessments of the structural integrity of the lens capsule in the human eye. This teaching can be used to detect potential lens capsule instability conditions that may indicate potential lens or lens capsule dislocation. As an example, and not a limitation, this teaching can be applied to assess suspensory ligament conditions and / or a patient's potential for accommodative intraocular lens placement or another surgical procedure. This method includes measuring and quantifying lens oscillations during the accurate and reproducible diagnosis of such conditions.

[0007] An embodiment of a method for assessing lens capsule instability includes simultaneously directing electromagnetic energy in a predetermined spectrum to the pupil of the eye via an energy source after eye movement causes eye saccades to occur. The method includes acquiring images of the eye indicating the saccades using an image capture device, and subsequently using these images via an electronic control unit (ECU) to calculate a motion curve of the lens capsule. The method further includes extracting a time-normalized lens capsule oscillation trajectory based on the curve via the ECU, and then model-fitting the lens capsule oscillation trajectory via the ECU to assess the lens capsule instability.

[0008] An alternative implementation of the method may include transmitting a dynamic gaze guidance cue to a visual target, wherein the visual target is positioned along the patient's line of sight. The gaze guidance cue induces a predetermined and controlled eye movement, referred to saccades below and in the general art, which occurs simultaneously with the induction of a characteristic Purkinje reflex in the light-based embodiment.

[0009] As part of this light-based embodiment of the method, a high-speed camera can be used to collect one or more images of characteristic Purkinje reflections, and an electronic control unit (ECU) calculates the motion curve of one of the characteristic Purkinje reflections (e.g., the P1 reflection), as described herein. Other embodiments may forgo initiating and detecting Purkinje reflections when diagnosing lens / capsule structural integrity as described herein, instead capturing other reflections or motions indicating lens capsule oscillations.

[0010] The method also includes extracting time-normalized lens oscillation trajectories based on motion curves via an ECU, and then performing model fitting on the time-normalized lens oscillation trajectories to diagnose the aforementioned lens / capsule structural conditions.

[0011] This document also discloses a system for diagnosing lens / capsule conditions. According to a representative embodiment, the system includes an energy source, such as IR or visible light, ultrasound energy, etc. The energy source is operable to direct electromagnetic energy toward a target location, which, during system operation, corresponds to the position of a human patient's eye. The system includes an image capturing device. When the image capturing device is a high-speed camera, a thermal mirror can be positioned relative to the camera at a predetermined angle. Such a mirror can be configured to direct reflected light from the target location toward the camera. An optional gaze-guided visual target can be positioned opposite the target location. When used as part of such a system, an ECU communicates with the energy source, the image capturing device, and the optional gaze-guided visual target.

[0012] In representative embodiments where the electromagnetic energy includes light waves in the visible or IR spectrum, this light can be directed onto the pupil at a predetermined intensity level sufficient to elicit a characteristic Purkinje reflex in the patient's pupil. In some embodiments, the ECU can be configured to transmit a gaze guidance cue to a visual target, thereby causing a change in the relative position of the visual target, which can occur simultaneously with the eliciting of the characteristic Purkinje reflex. In this case, the change in relative position is sufficient to elicit a saccade in the eye. However, as stated above, other types of imaging can be used in other embodiments, and therefore the characteristic Purkinje reflex is only one possible reflex within the scope of this disclosure.

[0013] The ECU is also configured to acquire images of characteristic Purkinje reflexes or other ocular reflexes, for example, using a high-speed camera or ultrasound reader, and subsequently use a processor to calculate one or more motion curves for a predetermined characteristic ocular reflex. The ECU extracts a time-normalized lens oscillation trajectory based on the curves and is also configured to perform model fitting on the time-normalized lens oscillation trajectory using a predetermined lumped mass model via the processor. The ECU, or the physician / surgeon using the ECU, then uses the results of this model fitting to diagnose potential unstable lens / capsule conditions.

[0014] In another possible embodiment, the ECU is configured for use with a high-speed video camera. In this embodiment, the ECU includes a processor, a transceiver communicating with the high-speed video camera and the visual target, and a memory on which computer-readable instructions are recorded. Execution of the instructions by the processor causes the processor to receive an image of the characteristic Purkinje reflection of P1 from the high-speed camera when an IR beam is directed onto the pupil of the eye.

[0015] Similarly, the execution of the command causes the ECU to transmit dynamic gaze guidance cues to the visual target, thereby causing the visual target to move sufficiently to trigger a predetermined eye saccade, which occurs simultaneously with the characteristic Purkinje reflex. In this particular embodiment, the ECU calculates the instantaneous velocity curve, acceleration curve, and / or position curve of the characteristic Purkinje reflex P1, extracts a time-normalized lens oscillation trajectory based on the motion curves(multiple), and uses a lumped mass model to model-fit the lens oscillation trajectory, thereby diagnosing the condition of the suspensory ligaments.

[0016] The above-described features and advantages of this disclosure, as well as other possible features and advantages, will become apparent from the following detailed description of the best mode for carrying out this disclosure, taken in conjunction with the accompanying drawings. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of an automated system for diagnosing or assessing potential lens / capsule-related structural conditions, according to this disclosure.

[0018] Figure 2 It is a schematic depiction of the typical Purkinje reflex within the human eye's pupil.

[0019] Figure 3 This is a schematic diagram of an exemplary sequence of alternating or dynamic visual cues that can be used as an optional part of this method.

[0020] Figure 4 This is a flowchart describing an exemplary method for diagnosing the type of lens / capsule condition described herein.

[0021] Figure 5A , Figure 5B and Figure 5C This is a schematic block diagram of a representative lumped mass model of scanned lens oscillations that can be used within the scope of this disclosure.

[0022] The foregoing and other features of this disclosure will become more fully apparent from the following description taken in conjunction with the accompanying drawings and the appended claims. The disclosure will be described with additional specificity and detail using the drawings, as it is understood that these drawings depict only a few embodiments according to this disclosure and should not be considered as limiting its scope. Any dimensions disclosed in the drawings or elsewhere herein are for illustrative purposes only. Detailed Implementation

[0023] This document describes embodiments of the present disclosure. However, it should be understood that the disclosed embodiments are merely examples, and other embodiments may take various alternative forms. These figures are not necessarily drawn to scale; some features may be enlarged or minimized to show details of specific components. Therefore, the specific structural and functional details disclosed herein should not be construed as limiting, but only as a representative basis for teaching those skilled in the art to employ the present disclosure in different ways. As will be understood by those skilled in the art, various features illustrated and described with reference to any of the figures may be combined with features illustrated in one or more other figures to produce embodiments not explicitly illustrated or described. The illustrated combinations of features provide representative embodiments for typical applications. However, for a particular application or implementation, various combinations and modifications of features consistent with the teachings of this disclosure may be required.

[0024] In the following description, certain terms may be used for illustrative purposes only and are therefore not intended to be limiting. For example, terms such as “above” and “below” refer to directions referenced in the accompanying drawings. Terms such as “front,” “rear,” “before,” “after,” “left,” “right,” “rear,” and “side” describe the orientation and / or position of portions of a component or element within a consistent but arbitrary frame of reference, as will become clear from the text describing the component or element under discussion and the associated accompanying drawings. Furthermore, terms such as “first,” “second,” and “third” may be used to describe individual components. Such terms may include the words specifically mentioned above, their derivatives, and words with similar meanings.

[0025] Referring to the accompanying drawings, where the same reference numerals refer to the same parts, Figure 1 An automated assessment system 10 is schematically depicted herein. System 10 is configured to infer the structural integrity of the lens / capsule structures within the eye 11 of a human patient, such as, but not limited to, the structural integrity of the suspensory ligaments and / or other tissues located behind the cornea 12 and iris 17 of the eye 11. For example, such a diagnosis or assessment could be a suspensory ligament insufficiency (ZI) condition or other conditions related to lens / capsule stability, as described herein, wherein the diagnosed condition is represented by a metric generated through a comprehensive process of video tracking, image analysis, and physical modeling.

[0026] Using this teaching in conjunction with preoperative and postoperative ocular assessments can help improve outcomes of cataract surgery planning, for example, by more accurately identifying potential intraoperative risks and helping to optimize lens selection. Postoperative use of this teaching in intraocular lenses can also aid in the diagnosis of visual impairment associated with various suspensory ligament problems. Similarly, as those skilled in the art will understand, this teaching can be beneficial for many other optical or ophthalmic procedures and / or diagnoses.

[0027] As specifically referenced in this article Figures 2 to 5CThe above, Figure 1 The automated assessment system 10 can be used to infer lens / capsule stability by measuring the movement of the lens located within the eye 11 during rapid eye movements or saccades. In some embodiments, the system 10 automatically tracks infrared light reflected from the cornea 12 and the lens. Due to the elastic suspension of the lens on the suspensory ligament fibers, the movement of the lens relative to the rest of the eye tissue begins with a slight delay and ends with an overshoot with characteristic oscillations. A prominent feature of ZI and other ocular conditions is significant lens instability, which in itself leads to alterations in lens / capsule oscillations. Therefore, model-based quantification of these altered oscillations is used as part of this method 50. Thus, the method described herein can be used to diagnose certain conditions of the eye 11 in a more accurate and patient-friendly manner compared to slit-lamp and other competing methods.

[0028] Figure 1 A possible non-limiting embodiment of the automated assessment system 10 shown includes an energy source 14 operable to direct electromagnetic energy (arrow LL) (e.g., light or ultrasonic energy) to the pupil 16 of the eye 11. In possible applications, the energy source 14 is an infrared (IR) light source, and the electromagnetic energy (arrow LL) is in the form of an IR beam in the eye-safe portion of the IR spectrum. During operation of the system 10, the pupil 16 thus forms a target position for being irradiated by the electromagnetic energy (arrow LL). In addition to the light source 14, the system 10 may also include an image capturing device 18, such as a high-speed camera. When the image capturing device 18 is embodied as a high-speed camera, the system 10 may also include a thermal mirror 20 arranged at a predetermined angle (θ) relative to the optical axis (AA), in a possible implementation, θ being approximately 15°. The thermal mirror 20 is thus configured to direct the reflected energy (LL) from the pupil 16... R The image is directed toward the image capture device 18. Alternatively, the lens capsule within the eye 11 can be imaged directly using the ultrasonic transducer 140, instead of light-based motion detection and tracking.

[0029] As part of the automated assessment system 10, an optional gaze-guided visual target 22 is positioned opposite the patient along the optical axis (AA). An electronic control unit (ECU) 25, as described further below, communicates with the power source 14, the image capture device 18, and the optional gaze-guided visual target 22. The ECU 25 is configured to execute computer-readable code or instructions embodying the method 50. Although schematically shown as a single schematic block for simplicity of illustration, the ECU 25 may include one or more networked devices, computer-readable media, or memories (M), including non-transitory (e.g., tangible) media involved in providing data / instructions that can be read by one or more processors P.

[0030] The memory (M) can take many forms, including but not limited to non-volatile media and volatile media. As will be understood, non-volatile media may include, for example, optical discs and / or magnetic disks, and other persistent memories, while volatile media may include dynamic random access memory (DRAM), static RAM (SRAM), etc., any or all of which may constitute main memory. Other hardware not depicted but established in the art may be included as part of ECU 25, including but not limited to input / output circuitry systems, local oscillators or high-speed clocks, buffers, latches, etc.

[0031] about Figure 1 The various components of the automated evaluation system 10 depicted herein, the energy source 14, may optionally be embodied as an IR light source suitable for the application, with a wavelength falling within the eye-safe portion of the electromagnetic spectrum, such as an IR wavelength greater than about 1.4 μm. Suitable options for use as the energy source 14 in such a non-limiting exemplary embodiment may include an IR light-emitting diode (LED), a continuous-wave laser, etc. Although the energy source 14 has been omitted for simplicity and clarity of illustration, it may be coupled to and / or include power supplies, filters, amplifiers, waveguides, and other components suitable for the generation and propagation of electromagnetic energy (arrow LL) to ensure suitable quality for the application.

[0032] The thermal mirror 20 can be embodied as a thermal reflector that operates as a short-pass edge filter, i.e., configured to transmit the visible wavelength of incident light while reflecting the IR / thermal wavelength toward the image capturing device 18. In this particular embodiment, the ECU 25 is configured to control the operation of the energy source 14 during operation of the system 10 to direct electromagnetic energy (arrow LL) to the pupil 16 of the eye 11. In some embodiments, a corrective optics 24 can be arranged along the optical axis (AA) between the eye 11 and the visual target 22 to ensure that the patient's focus is correctly fixed on and tracked by a moving gaze cue. Such a corrective optics 24 can be advantageously used for myopic patients or patients with other visual impairments, such as spherical / cylindrical defects, as an optional module of the corrective optics. Although for clarity and simplicity... Figure 1 The correction optics 24 are omitted, but in various embodiments, these correction optics may include mountings for manually switchable lenses, liquid lenses, and / or atomization systems.

[0033] As part of this method, electromagnetic energy (arrow LL) arrives at a predetermined intensity level sufficient to induce a characteristic reflection, such as a Purkinje reflection, in the pupil 16. The electromagnetic energy (arrow LL) is directed to the pupil 16, where the incident electromagnetic energy (arrow LL) propagates through the cornea 12 and the lens (not shown) and is reflected by them. In an IR / light-based embodiment, irradiation in this manner will produce four characteristic Purkinje reflections, a first characteristic Purkinje reflection P1 and a fourth characteristic Purkinje reflection P4. Figure 2 The examples shown herein are used in some of the embodiments.

[0034] Brief Reference Figure 2 The schematic diagram of eye 11 includes the iris 17, located at the center within the surrounding sclera 15, i.e., the sclera of eye 11. The Purkinje reflex, also known in the art as a Purkinje image or Purkinje-Samson image, is the externally visible reflection of an object within the pupil 16. The P1 Purkinje reflex, often the brightest of the Purkinje reflexes, is located within the region of the cornea 12 (see [reference needed]) in the pupil 16. Figure 1 The external region of the cornea 12 is visible. An inverted P4 Purkinje reflex is visible on the posterior surface of the cornea 12, also within the region of the pupil 16. P2 and P3 Purkinje reflexes are visible on the inner and anterior surfaces of the cornea 12; both reflexes originate from... Figure 2 The middle part is omitted. Therefore, in Figure 1 During operation of system 10, reflected light from eye 11 is intentionally deflected by angled thermal mirror 20 toward image capturing device 18, which in turn operates at a high frequency suitable for the application, for example, a shutter speed greater than about 300 Hz. In other embodiments, different techniques (e.g., optical coherence tomography (OCT) or ultrasound biomicroscopy (UBM)) may be used for lens position tracking, possibly replacing the aforementioned Purkinje reflection with direct imaging features of the lens / capsule structure.

[0035] Refer again Figure 1 For special reference below Figure 4 As part of the method 50 described herein, ECU 25 may optionally be configured to transmit a gaze guidance cue signal (arrow CC) to visual target 22. 22 This occurs simultaneously with the initiation of lens / capsule movement. Optional gaze guidance cue (arrow CC) 22 This causes the visual target 22 to change its relative position to a level sufficient to trigger a predetermined saccade of the eye 11, and thus triggers a detectable oscillation of the lens / capsule located therein.

[0036] like Figure 3 As shown, for example, a gaze guidance cue signal (arrow CC) is transmitted to visual target 22. 22This may include corresponding lighting devices L1 and L2 that illuminate the lighting panel 35 respectively. Lamp L1 and L2 may optionally be embodied as two (or more) discrete LEDs, incandescent bulbs, or other fast-illuminating light sources, spaced apart by a distance (d) and illuminated sequentially according to a predetermined order. Gaze guidance cues (arrow CC) 22 The LEDs can be implemented as a pair of side-by-side LEDs, for example, which are turned on and off alternately by the action of ECU25 or another control device, as indicated by arrows A and B. Other embodiments are conceivable, such as, but not limited to, projecting or displaying dynamic objects at alternating positions, for example, a video display configured to depict dynamic images, or any other suitable configuration. When the patient tracks the moving target, the eye 11 is induced to move within a predetermined range of motion, which induces lens oscillations in a controlled and repeatable manner.

[0037] Figure 1 The ECU 25 is also configured to acquire a set of images of the eye 11. This may include directly imaging the lens / capsule as described above, or it may involve indirect imaging, i.e., by transmitting energy control signals (arrow CC) to the energy source 14. 14 Combined with the above, a capture control signal (arrow CC) is transmitted to the image capture device 18. 18 The ECU 25 captures characteristic Purkinje reflexes P1 and P2. Subsequently, the ECU 25 calculates motion curves of the imaged lens / capsule motion via processor(P), which describe the motion of the lens capsule. This may require calculating instantaneous velocity, acceleration, position, and / or other curves for a predetermined characteristic Purkinje reflex (e.g., the first characteristic reflex P1) or any directly imaged landmark structure of the eye 11 (e.g., the lens itself). Additionally, the ECU 25 is configured to extract time-normalized lens oscillation trajectories based on the motion curves, and subsequently performs model fitting on the lens oscillation trajectories using a lumped mass model via processor(P). The results of this model fitting are then used to diagnose potential lens / capsule conditions, and the ECU 25 may output a data file 30 as an output signal (arrow CC). O Part of ).

[0038] refer to Figure 4 Used for inferring / diagnosing the eyes of human patients 11( Figure 1 and Figure 2 Method 50 for assessing potential lens / capsule structural instability within the lens begins at frame B52 (“Settings”), which may require relative to... Figure 1The automated assessment system 10 positions a human patient. For example, in some embodiments, the patient can be comfortably seated in a chair, facing a specific direction (e.g., toward an optional visual target 22), with the image capture device 18 located near the thermal mirror 20 and the power source 14. The patient then directs their gaze toward the visual target 22 and maintains this posture as method 50 advances to frame B54.

[0039] At box B54, the physician controls the automated assessment system 10 or ECU 25 itself via an energy control signal (arrow CC). 14 )Activate the operation of energy source 14 to transfer electromagnetic energy ( Figure 1 Arrow LL directs the eye toward eye 11 while the patient maintains focus on visual target 22. In a light-based implementation where the lens / capsule is indirectly imaged, electromagnetic energy (arrow LL) is maintained at an intensity level sufficient to elicit characteristic Purkinje reflexes P1 and P4 within pupil 16. If an optional corrective optics 24 is used as part of frame B52, frame B54 may require viewing visual target 22 through the intermediate corrective optics 24 to assist the patient in focusing on visual target 22 in a patient-vision-based manner. Optional dynamic gaze guidance cues (arrow CC) are transmitted to visual target 22, which is arranged along the line of sight of eye 11. 22 This triggers eye saccades, which occur simultaneously with the characteristic Purkinje reflex. Such dynamic gaze guidance cues (arrow CC) can be used if needed. 22 It can also be used in embodiments where the lens / capsule is directly imaged instead of Purkinje reflection imaging.

[0040] While this is in progress, ECU 25 can use image capture device 18 to acquire video, still, ultrasound, or other images of eye 11 (potentially including characteristic Purkinje reflexes). That is, as the patient's optical axis changes along with a moving image on visual target 22, image capture device 18 continuously acquires images and saves the collected images to the memory (M) of ECU 25. Alternatively, ECU 25 can save visual cues guided by each selectable gaze (arrow CC). 22 The discrete image sequence for each scan is defined by the time intervals before and after the occurrence of the image. The latter approach can help minimize data transmission load and subsequent image processing time. Method 50 can then proceed to optional box B56.

[0041] Box B56 can be used in embodiments where IR or other light is used to elicit the Purkinje reflex. In this case, box B56 needs to detect and identify the first characteristic Purkinje reflex P1 and the fourth characteristic Purkinje reflex P4 within the patient's eye 11 based on predetermined factors (e.g., intensity, size, shape, absolute position and / or relative position, i.e., the relative position of reflex P1 relative to reflex P4, or vice versa). Figure 2 As part of block B56, the processors (P) of ECU 25 can extract the corresponding coordinates of reflections P1 and P4 based on the geometric features (e.g., centroid) of each reflection, as will be understood by those skilled in the art. Method 50 then proceeds to block B58.

[0042] exist Figure 4 At box B58 of the depicted method 50, ECU 25 can normalize data from box B56 or from similar boxes that directly image the lens / capsule. For example, ECU 25 can extract lens movement and then correct for eye rotation 11. For example, in an embodiment capturing Purkinje reflections P1 and P4, this might require subtracting the coordinates of the first reflection P1 from the coordinates of P4. As part of box B58, ECU 25 can identify saccades to extract time-normalized lens oscillation trajectories. For example, individual saccades of eye 11 can be identified by calculating, for example, the motion curve of the point of interest for reflection P1. Detected velocity spikes represent the presence of saccades, and lens oscillations occur after such velocity spikes approach zero again. Method 50 then proceeds to box B60.

[0043] Box B60 of this particular embodiment of method 50 includes performing model fitting on the collected oscillation trajectories via ECU 25 to diagnose potential lens / capsule structural instability conditions. Two non-limiting example diagnostic applications of lens oscillation measurements according to this disclosure include the detection of suspensory ligament insufficiency (ZI) and the detection of accommodative IOL (aIOL) fitting, as generally described above, as well as many other lens stability-related conditions of the eye 11.

[0044] Specifically for ZI detection, measuring the fiber integrity of the suspensory ligament of the eye can be performed by estimating the suspensory ligament tension based on collected lens oscillation data. One possible algorithmic approach uses a kinetic model to fit the collected data; that is, estimating lens mass based on OCT biometry or other methods, and then fitting the model to the oscillation frequency and amplitude based on saccade eye stimulation, for example, by least-squares fitting with adjusted stiffness and damping terms. The ECU 25 can, for example, solve for the stiffness parameter k associated with the suspensory ligament tension. A simple linear lumped mass model may be sufficient for this application, while more complex models can be used to improve the fit to a given dataset.

[0045] For the aIOL assembly application of this teaching, methods for measuring accommodative function may include estimating suspensory ligament tension during different accommodative states and subsequently inferring ciliary muscle activity based on lens oscillation data. Among possible algorithmic approaches, Figure 1 The ECU 25 can use a dynamic model to fit the data and estimate lens mass based on OCT biometry or other methods suitable for fitting the model to oscillation frequencies and amplitudes. Such methods are also based on saccade eye stimuli under different accommodation states, for example, by using least squares fitting with adjusted stiffness and damping terms to solve for the stiffness parameter k and accommodation motion / tension range x0. For this purpose, a nonlinear lumped mass model can be used.

[0046] Further regarding frame B60, Figure 5A , Figure 5B and Figure 5C An example lumped mass dynamic model, usable in the context of Method 50, is described. The one-dimensional lumped mass model is capable of describing the system-level performance of saccadic eye movements. For example... Figure 5A As shown, a simplified representation of the radial arrangement of the suspensory ligament fibers connects a lens 19 with mass m to the ciliary muscle / ciliary body 60, such that the lens 19 is suspended from two anchor points (i.e., the ciliary body 60) by two springs 62 having a spring constant k. Figure 5A Spring 62 represents the suspensory ligament fiber. Pretension represents the ciliary muscle contraction state and is given by x0 (i.e., the distance between the anchor point and the mass (m)). The damping effect of the physiological environment is represented by a damper 61 arranged parallel to spring 62, which has a damping coefficient b.

[0047] Regarding x0, this value is a potential indicator of the suitability of aIOL. A decrease in tension during increased accommodation indicates contraction of the ciliary body at 60°, while a lack of tension change indicates a lack of this contraction. Regarding the spring constant k, this value is related to the stiffness of the system, primarily the tension of the suspensory ligaments. Therefore, a lack of stiffness can indicate potential surgical challenges.

[0048] For a linear oscillator, the system under discussion can be described mathematically as follows:

[0049]

[0050] Where m is again the concentrated mass of lens 19, and x is the linear displacement of lens 19 in resonant mode. It is the damping term, kx is the restoring force, and F(t) is the saccade actuation force based on the saccade acceleration curve.

[0051] For more complex nonlinear oscillators, different tuning states, i.e., ciliary body movement represented by x0, result in changes in the response amplitude, indicating nonlinearity. This nonlinearity may be part of the restoring force and damping force. Therefore, equation (1) can be modified as follows:

[0052]

[0053] In a nonlinear oscillator, the damping term in equation (1) Transform into a nonlinear function of equation (2) It can be a very complex nonlinear term, including terms such as combinations of extrusion membrane damping or viscoelastic properties. For example, the nonlinear function of equation (2) It can be represented as follows:

[0054] or

[0055]

[0056] The nonlinear behavior of the restoring force k(x) can be described as a nonlinear spring with a nonlinear spring force, for example:

[0057] k(x)=k eff (x+x0) p +k eff (x-x0) p .

[0058] exist Figure 5B The example nonlinear model is schematically depicted. The modified lumped mass model incorporates a damped viscoelastic model represented by Maxwell damping terms. Maxwell damping terms assume that another damper 161 is connected in series with another spring 162 and represent material properties such as creep and elasticity, which are well-known properties of suspensory ligaments in the art.

[0059] If the shape of the natural lens is measured during accommodation, for example using OCT, it can be improved by introducing another parameter x1 (referred to in this paper as the additional lens shape parameter). Figure 4 The influence of the presbyopic lens 19 is considered in the nonlinear model of C.

[0060] Refer again Figure 4 At box B62, method 50 includes calculating metrics, for example, by including different coefficients of one or more mechanical models as described above. Alternatively, individual metrics may be calculated based on key coefficients indicating, for example, the surgical problem, the suitability of the adjustable IOL selection, recommendations, etc. Different values ​​of single or multiple metrics will drive recommendations for many beneficial procedures, such as planning surgery based on indicated surgical problems, or determining the suitability of a given patient for receiving an adjustable IOL. The boundaries of these specific recommendations' metrics can be defined using patient groups in clinical studies.

[0061] Another potential implementation of this technology could be to determine the suitability of a ciliary muscle-driven accommodative IOL for a presbyopic patient by measuring their residual accommodation. See, for example, US Patent 9,456,739B2, issued October 4, 2016, to Campin et al., the entire contents of which are incorporated herein by reference. An aIOL is designed to retain accommodative ability after transplantation and relies on the normal function of the ciliary muscle for this. In a healthy eye, the ciliary muscle is relaxed when focusing on a distant object. This, in turn, places the suspensory ligament fibers and capsule under tension, which is ultimately transmitted to the lens. The lens thus flattens.

[0062] Therefore, in Figure 1 and Figure 2 During eye accommodation to a closer object, the ciliary muscle contracts, thereby reducing tension on the suspensory ligament fibers and capsule. This reduced tension allows the lens to increase its optical power. This difference in suspensory ligament fiber tension leads to different lens oscillation behaviors, with the accommodative state evoking stronger oscillations than the non-accommodative or far-focusing state. This effect is particularly noticeable in presbyopia. Therefore, the proposed mechanical model, used as part of this method 50, can be used to derive suspensory ligament tension from lens oscillation measurements. Comparing tension values ​​from the disclosed measurements over a range of accommodative demands allows for quantitative inference of ciliary muscle activity. That is, when the ciliary muscle contracts, tension decreases with increasing accommodative demand. When no change in tension is detected, it can be... Figure 1 The diagnostic results captured in the output file 30 show that ciliary muscle activity is negligible.

[0063] Appropriate ciliary muscle activity is crucial for the function of many novel accommodative IOL designs and may be an important screening factor before cataract surgery. When used to diagnose residual accommodative potential, Figure 1 The example hardware setup requires the presence of optics capable of providing different adjustment needs to the subject. As mentioned above, this can be achieved by... Figure 1The correction optics 24 are introduced into the optical path in a manner that allows for easy replacement or tuning. In this case, measurements are performed while perceiving the visual target 22 under two or more different accommodation requirements. A similar data analysis pipeline can be used for image analysis. When this teaching is applied to accommodation evaluation, the most significant difference is the increased complexity of the underlying mechanical model used as part of method 50.

[0064] Although the above references Figure 4 Exemplary method 50 and Figure 1 The automated assessment system 10 has been described, but those skilled in the art will understand that components or subsystems of system 10 can be used within the scope of this disclosure. For example, when diagnosing suspensory ligament insufficiency, ECU 25 can be used with an image capture device 18 embodied as a high-speed camera. In an exemplary embodiment, ECU 25 includes the aforementioned processor(P), and... Figure 1 The transceiver (Tx) that communicates between the image capture device 18 and the visual target 22, and the memory (M) thereon that records instructions for implementing the method 50.

[0065] The execution of this instruction causes (multiple) processors (P) to receive images of the eye 11 (potentially including P1 reflections and P4 reflections) from the image capturing device 18 when electromagnetic energy (arrow LL) is directed to the pupil 16 of the eye 11, as... Figure 1 and Figure 2 As shown, and transmits optional dynamic gaze guidance cues (arrow CC) to visual target 22. 22 This causes the visual target 22 or its display to move sufficiently to induce a predetermined eye saccade, which may occur simultaneously with the characteristic Purkinje reflection in the light-based embodiment. The execution of these instructions also causes processor(P)(p)(s) to calculate one or more motion curves of the detected lens motion, extract a time-normalized lens oscillation trajectory based on the curves(s), and use... Figures 5A to 5C One of the lumped mass models shown is used to fit the lens oscillation trajectory, thereby diagnosing the condition of the suspensory ligament.

[0066] therefore, Figure 1 Automated evaluation system 10 and reference Figures 2 to 5CThe described accompanying method 50 enables non-invasive diagnosis or assessment of the lens / capsule condition, residual accommodative potential / ciliary muscle activity, and other potentially beneficial ocular applications. This teaching allows physicians to accurately infer the structural state of the supporting structures within the eye 11 (e.g., the hidden suspensory ligaments of the eye 11) through measurements generated by the motion tracking, analysis, and physical modeling described above. Therefore, this teaching can help improve preoperative assessment. Similarly, this teaching can be extended to postoperative conditions, such as diagnosing visual impairment associated with potential suspensory ligament problems of the aforementioned types by assessing the intraocular lens eye. These and other benefits will be readily understood by those skilled in the art in light of this disclosure.

[0067] The detailed descriptions and accompanying drawings are supportive and descriptive of this disclosure, but the scope of this disclosure is defined only by the claims. While some best modes and other embodiments for implementing the claimed disclosure have been described in detail, various alternative designs and embodiments exist to practice the disclosure as defined in the appended claims.

[0068] Furthermore, the features of the embodiments shown in the accompanying drawings or the various embodiments mentioned in this specification are not necessarily to be construed as independent embodiments. Rather, each feature described in one of these examples of embodiments may be combined with one or more other desired features from other embodiments to produce other embodiments not described in words or with reference to the accompanying drawings. Therefore, such other embodiments fall within the scope of the appended claims.

Claims

1. A method for assessing the stability of the lens capsule in the eye of a human patient, the method comprising: After the movement of the eye causes saccades to occur, electromagnetic energy in a predetermined spectrum is simultaneously directed to the pupil of the eye via an energy source. Use an image capture device to acquire an image of the eyes that indicate the saccades of the eyes; The image is used by the electronic control unit (ECU) to calculate a motion curve describing the movement of the lens capsule; The ECU extracts the time-normalized lens capsule oscillation trajectory based on the motion curve; as well as The instability of the lens capsule is evaluated by model fitting the time-normalized lens capsule oscillation trajectory via the ECU.

2. The method as described in claim 1, wherein, The calculation of the motion curve includes calculating the position curve, instantaneous velocity curve, and / or acceleration curve.

3. The method as described in claim 2, wherein, The electromagnetic energy is light energy, the energy source is a light source, and the image capturing device is a camera, wherein acquiring an image of the eye includes acquiring an image of the characteristic Purkinje reflection within the eye.

4. The method of claim 3, wherein, The characteristic Purkinje reflex includes a P1 reflex with P1 coordinates and a P4 reflex with P4 coordinates, and the method further includes subtracting the P1 coordinates from the P4 coordinates via the ECU to correct the rotation of the eye.

5. The method of claim 3, wherein, The characteristic Purkinje reflection includes the P1 reflection, and wherein calculating the motion curve includes calculating the motion curve of the P1 reflection.

6. The method of claim 1, further comprising transmitting a dynamic gaze guidance cue to a visual target arranged along the line of sight of the eye, thereby triggering the eye saccade.

7. The method of claim 1, wherein, The image capturing device is a high-speed camera, and directing electromagnetic energy in the predetermined spectrum to the pupil of the eye via the energy source includes directing an infrared (IR) beam to the pupil, and acquiring an image of the eye indicating a scan of the eye includes using a thermal mirror to direct reflected IR light from the eye toward the high-speed camera.

8. The method of claim 1, wherein, Directing electromagnetic energy in the predetermined spectrum to the pupil of the eye includes using ultrasound energy to directly image the lens capsule, and wherein acquiring an image of the eye indicating a saccade of the eye includes collecting an ultrasound image of the lens capsule.

9. The method of claim 1, wherein, Model fitting of the lens capsule oscillation trajectory includes using a lumped mass model of the eye’s saccade actuation.

10. The method of claim 1, further comprising: Different adjustment needs are provided to the human patient via optical lenses, while the images are acquired; as well as The lens capsule oscillation trajectory was fitted using a nonlinear lumped mass model. Assessing the instability of the lens capsule includes detecting the ciliary muscle activity of the eye.

11. An automated system for assessing lens capsule instability in the eye of a human patient, the system comprising: An energy source configured to direct electromagnetic energy in a predetermined spectrum to the eye or into the eye while triggering an eye saccade; An image capturing device configured to acquire an image of the eye indicating a saccade of the eye; as well as An electronic control unit (ECU) communicates with the power source and the image capture device, wherein the ECU is configured to: The motion curve of the lens capsule is calculated using the image, wherein the motion curve describes the motion of the lens capsule; Based on the motion curve, the time-normalized lens oscillation trajectory is extracted; and The time-normalized lens oscillation trajectory is modeled to assess the lens capsule instability.

12. The automation system as described in claim 11, wherein, The electromagnetic energy is light energy, the energy source is a light source, and the image capturing device is a high-speed camera, wherein the image is an image of the characteristic Purkinje reflection within the eye.

13. The automation system as described in claim 12, wherein, The characteristic Purkinje reflex includes a P1 reflex with P1 coordinates and a P4 reflex with P4 coordinates, wherein the ECU is configured to subtract the P1 coordinates from the P4 coordinates via the ECU, thereby correcting the eye rotation.

14. The automation system of claim 12, wherein, The characteristic Purkinje reflection includes a P1 reflection, and the ECU is configured to calculate the motion curve of one of the characteristic Purkinje reflections by calculating the instantaneous velocity curve, instantaneous acceleration curve, and / or instantaneous position curve of the P1 reflection.

15. The automation system of claim 11, further comprising a visual target, wherein, The ECU is configured to transmit dynamic gaze guidance cues to the visual target to trigger eye saccades.

Images