Automated evaluation of the stability of the human lens capsule

Abstract

A method for assessing the stability of a lens capsule in a human patient's eye includes directing electromagnetic energy within a predetermined spectrum onto the pupil of the eye via an energy source, simultaneously following an eye movement that causes an eye saccade inward. The method also includes acquiring an image of the eye that indicates the eye saccade using an image capture device, and calculating, via an ECU, a lens capsule movement curve using the image. In addition, the method includes extracting, via the ECU, a time-normalized lens capsule vibration trace based on the movement curve, and then fitting, via the ECU, the lens capsule vibration trace to a model, thereby assessing the lens capsule instability. Also disclosed herein is an automated system for performing an embodiment of the method, including an energy source, an image capture device, and an ECU.

Description

Technical Field

[0001] The present disclosure relates to an automated method and system for non-invasively diagnosing or evaluating the stability of the potential lens capsule within the eye of a human patient. Non-limiting exemplary lens stability states that can be effectively diagnosed in accordance with the present teachings are those of zonular insufficiency (ZI). In addition, the solutions described herein can be adapted for the evaluation of candidate patients for accommodative intraocular lens (aIOL) devices, for example, during the preoperative fitting process, in determining an optimal cataract surgery plan, or in evaluating a patient's accommodative ability. Similarly, preoperative, postoperative, diagnostic, or treatment procedures related to the stability of the lens capsule or general eye health can also benefit from the present teachings.

[0002] The lens of the human eye includes a lens capsule, epithelium, and supporting fibers. The lens capsule is specifically a thin transparent membrane whose outer periphery is fixed to a ring of elastic fibers known in the art as the zonular membrane / zona, or simply the zonules. The ciliary muscle within the eye contracts or relaxes to act collectively on the zonules during accommodation, which has the effect of changing the shape of the lens capsule. Thus, the zonules provide the benefits of proper eye function by appropriately adjusting the various forces applied to the lens by the ciliary muscle and fixing the lens capsule along the optical axis.

[0003] The above-described ZI condition exists when the zonules are overly elastic or "floppy." Thus, the lens and capsular bag can become weakly attached to the ciliary muscle. As a result, patients diagnosed with the ZI condition are at a higher risk of experiencing some complication during cataract surgery, lens exchange, or aIOL device insertion. Surgeons operating on ZI patients may attempt to reduce the surgical risk by using a capsular support device to stabilize the capsule, by performing a laser-based capsulotomy procedure, or by taking other preventive measures.

[0004] The size of the zonule is approximately several tens of micrometers. The extremely small size of the zonule behind the iris and its well-occluded location prevent effective direct optical examination of the zonule's structural integrity. Therefore, the presence of a ZI condition in a given patient is usually revealed indirectly, for example, using slit-lamp examination, in which a surgeon stimulates the patient's body to induce eye movements. For example, a clinician may tap the headrest supporting the patient's head or lightly tap the side of the patient's head directly to provide manual stimulation. As an alternative approach, ultrasound stimulation may be used.

[0005] Regardless of the approach used, patients may experience increased anxiety because they anticipate the arrival of stimulation. Ultrasound stimulation, in particular, generally requires direct contact between the ultrasound device and the patient's eye. Furthermore, diagnostic results tend to be highly skill-dependent and subjective. Consequently, potential ZI conditions or other capsule instability may be unexpectedly discovered, for example, during ophthalmic surgery, which could negatively impact the surgical outcome or necessitate changes to the surgical plan. [Overview of the project]

[0006] Disclosed herein are methods and systems for performing automated assessment of the structural integrity of the lens capsule of a human eye. These instructions may be used to detect potential instability of the lens capsule that could predict potential lens or lens capsule dislocation. For example, but not limited to, these instructions may be applied to assess the condition of the zonule and / or the likelihood of a patient receiving an accommodative intraocular lens or another surgical procedure. The approach involves measuring and quantifying lens vibration in the process of accurately and reproducibly diagnosing such conditions.

[0007] One embodiment of a method for evaluating the instability of the lens capsule includes simultaneously guiding electromagnetic energy within a predetermined spectrum onto the pupil of the eye via an energy source after an eye movement that generates an internal ocular saccade. The method includes acquiring an image of the eye indicating the ocular saccade using an image acquisition device, and then calculating a motion curve of the lens capsule using the image via an electronic control unit (ECU). The method further includes extracting a time-normalized lens capsule oscillation trace based on the curve via the ECU, and then fitting the lens capsule oscillation trace to a model via the ECU to evaluate the instability of the lens capsule.

[0008] An optional implementation of this method may include sending dynamic gaze-guided cues to a target, which is positioned along the patient's line of sight. The gaze-guided cues induce a predetermined controlled eye movement, referred to below and in general art as an ocular saccade. In the light-based embodiment, the induced ocular saccade occurs simultaneously with the induction of a characteristic Purkinje reflex.

[0009] As part of such an optical-based embodiment of the method, one or more images of characteristic Purkinje reflections may be acquired using a high-speed camera, and an electronic control unit (ECU) calculates a motion curve for one of the characteristic Purkinje reflections, for example, the P1 reflection as described herein. Other embodiments may choose to incorporate other reflections or motions indicating capsule oscillations when diagnosing the structural integrity of the lens / capsule as described herein, and may not perform the induction and detection of Purkinje reflections.

[0010] This method also includes extracting time-normalized lens vibration traces based on motion curves via the ECU, and then fitting the time-normalized lens vibration traces to a model to diagnose the state of the lens / capsule structure described above.

[0011] Furthermore, this specification discloses a system for diagnosing the condition of the lens / capsule. According to a typical embodiment, the system includes an energy source, such as IR or visible light, ultrasonic energy, etc. The energy source is operable to guide electromagnetic energy toward a target position, which coincides with the position of the human patient's eye when the system is in operation. The system includes an image acquisition device. When the image acquisition device is a high-speed camera, a hot mirror may be positioned at a predetermined angle to the camera. Such a mirror may be configured to guide light reflected from the target position toward the camera. An optional gaze-guiding target may be positioned opposite the target position. When used as part of such a system, an ECU communicates with the energy source, the image acquisition device, and the optional gaze-guiding target.

[0012] In typical embodiments where the electromagnetic energy includes light waves in the visible or IR spectrum, such light can be guided onto the pupil at a predetermined intensity level sufficient to induce a characteristic Purkinje reflex within the patient's pupil. In some embodiments, the ECU may be configured to send gaze-guided cues to a target, which may occur simultaneously with inducing the characteristic Purkinje reflex, thereby changing the relative position of the target. In this example, the change in relative position is sufficient to induce a saccade within the eye. However, as described above, other embodiments may employ other types of imaging, and therefore the characteristic Purkinje reflex is merely one possible reflex within the scope of this disclosure.

[0013] The ECU is also configured to acquire images of characteristic Purkinje or other eye reflexes, for example, using a high-speed camera or ultrasound reading, and then use a processor to calculate the motion curves of one or more of the given characteristic eye reflexes. Based on the curves, the ECU extracts a time-normalized lens vibration trace and is also configured, via the processor, to perform model fitting of the time-normalized lens vibration trace using a given lumped mass model. The ECU, or the practitioner / surgeon using the ECU, then uses the results of such model fitting to diagnose the condition of the lens / capsule that may be unstable.

[0014] In another possible embodiment, the ECU is configured for use with a high-speed video camera. The ECU in this embodiment includes a processor, a transceiver for communicating with the high-speed video camera and a target, and a memory in which computer-readable instructions are stored. The execution of instructions by the processor causes the processor to receive an image of the P1 characteristic Purkinje reflection from the high-speed camera as an IR light beam is guided over the pupil of the eye.

[0015] Similarly, the execution of a command causes the ECU to send a dynamic gaze induction cue to the target, thereby causing the target to move sufficiently to induce a predetermined ocular saccade, which is done simultaneously with the characteristic Purkinje reflex. In this particular embodiment, the ECU calculates the instantaneous velocity, acceleration, and / or position curves of the P1 characteristic Purkinje reflex, extracts a time-normalized lens vibration trace based on the motion curve, and fits the lens vibration trace to a model using a lumped mass model, thereby diagnosing the state of the zonule.

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

[0017] [Figure 1]Figure 1 is a schematic diagram of an automated system for diagnosing or evaluating potential lens / capsule-related structural conditions as described herein. [Figure 2] Figure 2 is a schematic diagram of a typical characteristic Purkinje reflex within the pupil of a human eye. [Figure 3] Figure 3 is a schematic diagram of exemplary sequences of alternating or dynamic visual cues that can be used as an optional part of this method. [Figure 4] Figure 4 is a flowchart illustrating an exemplary method for diagnosing the conditions of the types of lens / capsule described herein. [Figure 5A-5C] Figures 5A-5C are schematic block diagrams of typical condensed mass models of saccade crystalline vibrations available within the scope of this disclosure. [Modes for carrying out the invention]

[0018] The features described above and other features of this disclosure will be more fully apparent from the following description and the appended claims, in conjunction with the accompanying drawings. While understanding that these drawings only illustrate some embodiments relating to this disclosure and should not be considered limiting, this disclosure is described with further specificity and detail through the use of the accompanying drawings. Any dimensions disclosed in the drawings or elsewhere in this specification are for illustrative purposes only.

[0019] Embodiments of the present disclosure are described herein. However, it should be understood that the embodiments of the present disclosure are merely examples, and other embodiments may take various and alternative forms. The figures are not necessarily to scale, and some features may be exaggerated or minimized to illustrate details of particular components. Accordingly, certain structural and functional details disclosed herein should not be construed as limitations, but rather as representative grounds for teaching those skilled in the art to make various uses of the present disclosure. As those skilled in the art will understand, various features illustrated and described with reference to any one of the figures can be combined with features illustrated in one or more other figures to create embodiments not expressly illustrated or described. Combinations of illustrated features result in representative embodiments for typical applications. However, various combinations and modifications of features consistent with the teachings of the present disclosure may be desirable for particular applications or implementations.

[0020] Certain technical terms are used for reference purposes only in the following explanation and are therefore not intended to be limiting. For example, terms such as "above" and "below" refer to directions within the referenced drawings. Terms such as "front," "back," "fore," "aft," "left," "right," "rear," and "side" describe the orientation and / or location of a component or part of an element within a consistent, but arbitrary, coordinate system, as revealed by referring to the text and related drawings describing the component or element being discussed. Furthermore, terms such as "first," "second," "third," etc., may be used to describe separate components. Such technical terms may include the words specifically mentioned above, their derivatives, and equally important words.

[0021] Referring to the drawings, similar reference numerals refer to similar components, and Figure 1 schematically shows the automated evaluation system 10. The system 10 is configured to infer the structural integrity of the lens / capsule structure within a human patient's eye 11, including, but not limited to, the structural integrity of the zonule and / or other tissues located behind the cornea 12 and iris 17 of the eye 11. For example, such a diagnosis or evaluation may be of a zonule insufficiency (ZI) condition or other condition related to lens / capsule stability as described herein, and the diagnosed condition is represented by metrics generated through an integrated process of video tracking, image analysis, and physical modeling.

[0022] The use of these instructions in conjunction with preoperative and postoperative eye evaluations may help improve the outcomes of cataract surgery planning, for example, by more accurately identifying potential intraoperative risks and assisting in optimal lens selection. When used postoperatively with pseudophakic eyes, these instructions may also help diagnose visual impairments related to various zonular problems. Similarly, these instructions may be useful for numerous other optical or ophthalmic procedures and / or diagnoses, as will be understood by those skilled in the art.

[0023] As described in particular reference to FIGS. 2-5C herein, the automated evaluation system 10 of FIG. 1 can be used to infer lens / capsule stability by measuring the movement of the lens located within the eye 11 during high-speed eye movements or saccades. System 10, in some embodiments, automatically tracks infrared light reflected from the cornea 12 and the lens. Due to the elastic suspension of the lens on the zonular fibers, the movement of the lens relative to the remaining eye tissue starts with some delay and ends with an overshoot with characteristic vibrations. The ZI state and other eye states are broadly characterized by significant lens instability that results in abnormal lens / capsule vibrations by itself. Therefore, a model-based quantification of such abnormal vibrations is used as part of this method 50. As a result, the approach described herein can be used to diagnose specific states of the eye 11 in a more accurate and patient-friendly manner compared to slit lamps and other competing approaches.

[0024] A possible non-limiting embodiment of the automated evaluation system 10 shown in FIG. 1 includes an energy source 14 operable to guide electromagnetic energy (arrow LL), e.g., light or ultrasonic energy, onto the pupil 16 of the eye 11. In a possible application, the energy source 14 is an infrared (IR) light source and the electromagnetic energy (arrow LL) is in the form of an IR light beam within the eye-safe portion of the IR spectrum. Therefore, during operation of the system 10, the pupil 16 forms a target position for irradiation by the electromagnetic energy (arrow LL). In addition to the light source 14, the system 10 may include an image capture device 18 such as a high-speed camera. When the image capture device 18 is embodied as such, the system 10 may also include a hot mirror 20, which is disposed at a predetermined angle (θ) with respect to the optical axis (AA), and θ is, in a possible implementation, about 15°. Therefore, the hot mirror 20 is configured to guide the energy (arrow LLR) reflected from the pupil 16 towards the image capture device 18. Alternatively, instead of light-based motion detection and tracking, an ultrasonic transducer 140 may be used to directly image the lens capsule within the eye 11.

[0025] As part of the automatic evaluation system 10, an optional fixation-inducing visual target 22 is positioned along the optical axis (AA) opposite the patient. An electronic control unit (ECU) 25, as further described below, communicates with the energy source 14, the image capture 18, and the optional fixation-inducing visual target 22, and the ECU 25 is configured to execute computer-readable code or instructions embodying the method 50. Although schematically shown as a single-frame schematic for simplicity of illustration, the ECU 25 may include a computer-readable medium or memory (M) including one or more networked devices, a non-transitory (e.g., tangible) medium involved in providing data / instructions readable by one or more processors P.

[0026] 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 can include, for example, optical or magnetic disks and other permanent memories, while volatile media can include dynamic random-access memory (DRAM), static RAM (SRAM), etc., any or all of which can constitute main memory. Although not shown, other hardware established in the art, including, but not limited to, input / output circuitry, local oscillators or high-speed clocks, buffers, latches, etc., may be included as part of the ECU 25.

[0027] With respect to the various components of the automated evaluation system 10 shown in Figure 1, the energy source 14 can optionally be embodied as an application-appropriate IR light source having an IR wavelength greater than the eye-safe portion of the electromagnetic spectrum, for example, about 1.4 μm. Suitable choices for use as the energy source 14 in such a non-limiting exemplary embodiment include IR light-emitting diodes (LEDs), continuous-wave lasers, etc. Although omitted for brevity and clarity of the example, the energy source 14 may be coupled to and / or include a power supply, filters, amplifiers, waveguides, and other components suitable for ensuring the generation and propagation of electromagnetic energy (arrow LL) of an application-appropriate quality.

[0028] The hot mirror 20 may be embodied as a thermal reflective mirror configured to act as a short-path edge filter, i.e., to transmit visible wavelengths of incident light while reflecting IR / thermal emission wavelengths toward the image acquisition device 18. In this particular embodiment, the ECU 25 is configured to control the operation of the energy source 14 to guide electromagnetic energy (arrow LL) onto the pupil 16 of the eye 11 during the operation of the system 10. In some embodiments, a corrective optical element 24 may be positioned along the optical axis (AA) between the eye 11 and the target 22 to ensure proper fixation and tracking of the patient's focus on a moving gaze cue. Such a corrective optical element 24 may be used as an optional module for corrective optics to benefit patients with myopia or other visual impairments, such as spherical / cylindrical defects. Although omitted from Figure 1 for clarity and brevity, the corrective optical element 24 may, in various embodiments, include a mount for a manually switchable lens, a liquid lens, and / or a fogging system.

[0029] As part of this approach, electromagnetic energy (arrow LL) arrives at a predetermined intensity level sufficient to induce a characteristic reflex, such as a Purkinje reflex, within the pupil 16. The electromagnetic energy (arrow LL) is guided over the pupil 16, where it propagates through the cornea 12 and lens (not shown) and is reflected by them. Irradiation in this manner will produce four characteristic Purkinje reflexes in IR / light-based embodiments. The first and fourth characteristic Purkinje reflexes P1 and P4 are shown in Figure 2 and are used in several embodiments herein.

[0030] Referring briefly to Figure 2, the schematic diagram of the eye 11 includes the surrounding sclera 15, i.e., the iris 17 located in the center of the white of the eye 11. The Purkinje reflex, also referred to in the art as the Purkinje image or Purkinje-Samson image, appears as an externally visible reflection of an object within the pupil 16. The P1 Purkinje reflex, which tends to be the brightest of the Purkinje reflexes, is visible on the outer region of the cornea 12 (see Figure 1) within the pupil 16 region. The inverted P4 Purkinje reflex is similarly visible on the posterior surface of the cornea 12 within the pupil 16 region. The P2 and P3 Purkinje reflexes, both omitted from Figure 2, are visible on the inner and anterior surfaces of the cornea 12. Therefore, during the operation of the system 10 in Figure 1, the light reflected from the eye 11 is intentionally deflected towards the image acquisition device 18 by the angled hot mirror 20. On the other hand, the image acquisition device 18 operates at a shutter speed greater than approximately 300 Hz, which is a frequency suitable for the application. In other embodiments, different techniques, such as optical coherence tomography (OCT) or ultrasonic biomicroscopy (UBM), may be used for tracking the position of the lens, sometimes using directly imaged features of the lens / capsule structure instead of the Purkinje reflection described above.

[0031] Referring again to Figure 1, as part of the method 50 described below with particular reference to Figure 4, the ECU 25 may be optionally configured to send a gaze-guided cue signal (arrow CC22) to the target 22 at the same time as inducing lens / capsule motion. The optionally selected gaze-guided cue signal (arrow CC22) causes the target 22 to change its relative position to a level sufficient to induce a predetermined saccade of the eye 11, and as a result induce a detectable vibration of the lens / capsule located within it.

[0032] As shown in Figure 3, for example, sending a gaze guidance cue signal (arrow CC22) to the target 22 may include separately illuminating the respective illumination devices L1 and L2 of the illumination panel 35. The lights L1 and L2 may optionally be embodied as two (or more) discrete LEDs, incandescent bulbs, or other fast-illuminating light sources that are spaced apart from each other by a distance (d) and illuminated sequentially according to a predetermined sequence. The gaze guidance cue signal (arrow CC22) could be implemented, for example, as a pair of side-by-side LEDs that are switched on and off alternately as indicated by arrows A and B by the action of the ECU 25 or another control device. Other embodiments may also be considered, but not limited to, projection or display of dynamic objects at alternating positions, such as a video display configured to show a dynamic image, or any other suitable configuration. When the patient tracks a motor target, the eye 11 is moved over a predetermined range of motion, and such eye movements induce controlled and reproducible crystalline lens oscillations.

[0033] The ECU 25 in Figure 1 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 include indirect imaging by acquiring characteristic Purkinje reflections P1 and P2 via the transmission of an acquisition control signal (arrow CC18) to the image acquisition device 18, in conjunction with the transmission of an energy control signal (arrow CC14) to the energy source 14, as described above. The ECU 25 then calculates motion curves of the acquired lens / capsule motion that describe the motion of the lens / capsule via the processor (P). This may require calculating curves for predetermined characteristic Purkinje reflections, such as the first characteristic reflection P1, or for any directly imaged landmark structures of the eye 11, such as the instantaneous velocity, acceleration, position, and / or other curves of the lens itself. In addition, the ECU 25 is configured to extract a time-normalized lens vibration trace based on the motion curves and then, via the processor (P), perform a model fitting of the lens vibration trace using a lumped mass model. Next, the results of this model fitting are used to diagnose the potential state of the lens / capsule, and in some cases, the ECU25 outputs the data file 30 as part of the output signal (arrow CCO).

[0034] Referring to Figure 4, Method 50 for inferring / diagnosing potential structural instability of the lens / capsule within the eye 11 (Figures 1 and 2) of a human patient begins in Block B 52 ("Preparation"), which may require positioning the human patient for the automated evaluation system 10 in Figure 1. For example, the patient may be seated comfortably in a chair facing a specific direction toward an optional target 22, and the image acquisition device 18 may be positioned adjacent to the hot mirror 20 and energy source 14, depending on the embodiment. The patient then turns their gaze toward the target 22 and maintains this posture while Method 50 proceeds to Block B 54.

[0035] In block B54, the practitioner controlling the automated evaluation system 10, or the ECU 25 itself, initiates the operation of the energy source 14 via an energy control signal (arrow CC14), guiding electromagnetic energy (arrow LL in Figure 1) toward the eye 11 while the patient maintains focus on the target 22. In light-based implementations where the lens / capsule is indirectly imaged, the electromagnetic energy (arrow LL) is maintained at an intensity level sufficient to induce characteristic Purkinje reflexes P1 and P4 in the pupil 16. If an optional corrective optical element 24 is employed as part of block B52, then block B54 may require the patient to view the target 22 through the intervening corrective optical element 24 in order to assist the patient in focusing on the target 22 in a manner based on the patient's visual acuity. Simultaneously with the characteristic Purkinje reflexes, an optional dynamic gaze guidance cue (arrow CC22) is sent toward the target 22 positioned along the line of sight of the eye 11, thereby inducing an ocular saccade. Such dynamic gaze guidance cues (arrow CC22) may also be used, if desired, in embodiments in which the lens / capsule is directly imaged, as opposed to imaging the Purkinje reflector.

[0036] While this is in progress, the ECU 25 may use the image acquisition device 18 to acquire video, still, ultrasound, or other images of the eye 11, possibly including characteristic Purkinje reflexes. That is, as the patient's optical axis changes in conjunction with the motion image on the visual target 22, the image acquisition device 18 continuously acquires images and stores the acquired images in the memory (M) of the ECU 25. Alternatively, the ECU 25 may store discrete image sequences for each saccade, defined by the time intervals before and after the appearance of each optional gaze-guided visual cue (arrow CC 22). The latter approach may help minimize data transfer load and subsequent image processing time. Method 50 may then proceed to an optional block B 56.

[0037] Block B56 may be used in embodiments in which Purkinje reflexes are induced using IR or other light. In such cases, Block B56 is required to detect and identify first and fourth characteristic Purkinje reflexes P1 and P4 (see Figure 2) in the patient's eye 11 based on predetermined factors, such as intensity, size, shape, absolute position, and / or relative position, i.e., the relative position of reflection P1 to reflection P4, or vice versa. As part of Block B56, the processor (P) of ECU 25 may extract the corresponding coordinates of reflections P1 and P4 based on the geometric features of each, such as the centroid, as will be understood by those skilled in the art. Method 50 then proceeds to Block B58.

[0038] In block B58 of method 50 shown in Figure 4, ECU25 may normalize data from block B56 or from similar blocks in which the lens / capsule is directly imaged. For example, ECU25 may extract lens motion and then correct for eye 11 rotation. In implementations that capture P1 and P4 Purkinje reflections, this may require subtracting the coordinates of the first reflection P1 from the coordinates of P4. As part of block B58, ECU25 may identify saccades and extract time-normalized lens vibration traces. Individual saccades of eye 11 may be identified, for example, by calculating the motion curve of the point of interest, of reflection P1. Detected velocity spikes represent the presence of saccades, and lens vibration occurs after such velocity spikes approach zero. Method 50 then proceeds to block B60.

[0039] Block B60 of this particular embodiment of Method 50 includes performing a model fitting on the collected vibration traces via the ECU25, thereby diagnosing potential structural instability conditions of the lens / capsule. Two non-limiting exemplary diagnostic applications for lens vibration measurement according to this disclosure include the detection of zonular insufficiency (ZI) and the detection of accommodative IOL (aIOL) fit, as broadly described above, along with many other conditions related to lens stability of the eye 11.

[0040] In particular, for ZI detection, measuring the fibrous integrity of the zonule within the eye 11 can be performed by estimating the zonule tension based on collected lens vibration data. A possible algorithmic approach is to fit the collected data using a dynamic model. That is, the lens mass is estimated based on OCT biometric measurements or other methodologies, and then the model is fitted to the vibration frequency and amplitude based on saccade eye stimulation. For example, least-squares fitting is performed by adjusting the stiffness and damping terms. ECU 25 could, for example, be solved for a stiffness parameter k that correlates with the zonule tension. A simple linear lumped mass model may suffice for this application, while more complex models may be used to improve the fit to a given dataset.

[0041] For the application of aIOL fitting in this instruction, approaches to measure accommodation function may include estimating zonular tension between different accommodation states and then inferring ciliary muscle activity based on lens vibration data. In a possible algorithmic approach, the ECU25 in Figure 1 could be fitted to data using a dynamic model, and the lens mass could be estimated based on OCT biometric measurements or other methods suitable for fitting the model to vibration frequency and amplitude. Such approaches are similarly based on saccadic eye stimulation in different accommodation states, solving for the stiffness parameter k and accommodation motion / tension range x0 using least-squares fitting by adjusting the stiffness and damping terms, for example. A nonlinear lumped mass model may be used for this purpose.

[0042] Furthermore, with respect to block B60, Figures 5A, 5B, and 5C show exemplary concentrated mass dynamic models usable in the context of Method 50. A one-dimensional concentrated mass model can describe the system-level behavior for saccadic eye movements. As shown in Figure 5A, a simplified representation of the radial arrangement of zonular fibers connects a lens 19 having mass m to the ciliary muscle / ciliary body 60, thereby suspending the lens 19 from two anchoring points, i.e., the ciliary body 60, by two springs 62 having spring constant k. In Figure 5A, the springs 62 represent zonular fibers. The initial tension represents the contraction state of the ciliary muscle and is given by x0, i.e., the distance from the anchoring point to the mass (m). The damping effect of the physiological environment is represented by a dashpot 61 positioned parallel to the springs 62, the dashpot 61 having a damping coefficient b.

[0043] With respect to x0, this value is a potential suitability indicator for aIOL. A decrease in tension during an increasing regulatory requirement indicates the presence of ciliary body 60 contraction, while a lack of tension change indicates a lack of such contraction. With respect to the spring constant k, this value correlates with the stiffness of the system, primarily the tension of the ligament. Therefore, a lack of stiffness may indicate a potential surgical challenge.

[0044] For a linear oscillator, the system in question can be mathematically described as follows:

number

number

[0045] For more complex nonlinear oscillators, the response amplitude changes for different regulated states, i.e., ciliary motion represented by x0, indicating nonlinearity. Such nonlinearity is likely the restoring and damping force components. Therefore, equation (1) can be modified to:

number

number

number

number

number

[0046] Figure 5B schematically shows an exemplary nonlinear model. The modified lumped mass model incorporates a viscoelastic model of damping, represented by a Maxwell damping term. The Maxwell damping term assumes another dashpot 161 in series with another spring 162 and represents material properties such as creep and elasticity, which are well-established in the art.

[0047] For example, if the natural lens shape is measured during accommodation using OCT, the effect of presbyopic lens 19 may be considered in the nonlinear model of Figure 5C by introducing another parameter x1, which is referred to herein as an additional lens shape parameter.

[0048] Referring again to Figure 4, in block B62, method 50 includes calculating a metric, for example, by including different coefficients of the mechanical model or set of models as described above. Alternatively, separate metrics could be calculated based on key coefficients indicating, for example, surgical problems, suitability for adjustable IOL selection, recommendations, etc. Different values ​​of one or more metrics would lead to recommendations for a number of beneficial processes, such as planning surgery according to the indicated surgical problem or determining the suitability of a given patient for accepting an adjustable IOL. The boundaries of the metrics for these specific recommendations may be defined using patient cohorts in clinical studies.

[0049] Another potential implementation of this technology could be determining the suitability of presbyopic patients for receiving ciliary muscle-driven accommodative IOLs by measuring the patient's remaining accommodation. See, for example, the patent to Campin et al., U.S. Patent No. 9,456,739B2, issued on 4 October 2016, which is incorporated herein by reference in its entirety. an IOL is designed to retain accommodative ability after implantation, and to achieve this objective, it relies on the proper functioning of the ciliary muscle. In a healthy eye, the ciliary muscle is relaxed during fixation to distant objects. This, in turn, places tension on the zonules and sacrum, and such tension is eventually transmitted to the lens. As a result, the lens becomes flattened.

[0050] Therefore, during accommodation of the eye 11 to a closer object in Figures 1 and 2, the ciliary muscle contracts, thereby reducing the tension on the zonules and sac. This reduced tension allows the lens to increase its refractive power. This difference in the tension of the zonules induces different crystalline lens oscillation behaviors, with the accommodative state inducing stronger crystalline lens oscillation than the unaccommodative or far-focus state. This effect is pronounced in presbyopia. Thus, the proposed mechanical model used as part of the method 50 can be used to derive zonule tension from measurements of crystalline lens oscillation. By comparing tension values ​​from measurements in the disclosure over a range of accommodative demands, quantitative estimation of ciliary muscle activity becomes possible. That is, when the ciliary muscle contracts, the tension decreases with increasing accommodative demands. When no change in tension is detected, the diagnostic result that may be incorporated into the output file 30 of Figure 1 is that the ciliary muscle activity is negligible.

[0051] Appropriate ciliary muscle activity response is crucial for the function of many new adjustable IOL designs and can be an important screening factor prior to cataract surgery. When used to diagnose residual accommodative potential, the exemplary hardware mechanism in Figure 1 requires the presence of an optical element capable of presenting different accommodative needs to the subject. This can be achieved by introducing the corrective optical element 24 of Figure 1 into the optical path in a manner that allows for easy replacement or adjustment, as described above. Measurements in this example are performed using visual targets 22 perceived in two or more different accommodative needs. The data analysis pipeline may be similar for image analysis. The most significant difference when applying this instruction to accommodation assessment is the higher complexity of the underlying dynamical model used as part of Method 50.

[0052] The above has been described with reference to the exemplary method 50 in Figure 4 and the automated evaluation system 10 in Figure 1, but those skilled in the art will understand that components or subsystems of the system 10 can be used within the scope of this disclosure. For example, when diagnosing a zonules insufficiency, the ECU 25 may be used in conjunction with an image acquisition device 18 embodied as a high-speed camera. In an exemplary embodiment, the ECU 25 includes the above-described processor (P), a transceiver (Tx) that communicates with the image acquisition device 18 and target 22 in Figure 1, and a memory (M) in which instructions for performing the method 50 are recorded.

[0053] Execution of such instructions causes the processor (P) to receive an image of the eye 11 from the image acquisition device 18, potentially including P1 and P4 reflections, as electromagnetic energy (arrow LL) is guided over the pupil 16 of the eye 11, as shown in Figures 1 and 2, and to send an optional dynamic gaze guidance cue (arrow CC22) to the target 22, thereby moving the target 22 or the display on it sufficiently to induce a predetermined ocular saccade, which in the light-based embodiment may be done simultaneously with characteristic Purkinje reflections. Execution of the instructions also causes the processor (P) to calculate one or more motion curves of the detected lens motion, extract a time-normalized lens vibration trace based on the curves, and fit the lens vibration trace to a model using one of the lumped mass models shown in Figures 5A to 5C, thereby diagnosing the state of the zonule.

[0054] Thus, the automated evaluation system 10 of Figure 1 and the accompanying method 50 described with reference to Figures 2-5C enable non-invasive diagnosis or evaluation of the state of the lens / capsule, as well as residual accommodative potential / ciliary muscle activity and other possible beneficial ophthalmic applications. This instruction enables the practitioner to accurately infer the structural state of supporting structures within the eye 11, such as the hidden zonule of the eye 11, through metrics generated via the motion tracking, analysis, and physical modeling described above. Therefore, this instruction can help improve preoperative evaluation. Similarly, this instruction can be extended to postoperative situations, such as evaluating pseudophakic eyes and diagnosing visual impairment related to the types of potential zonule problems described above. These and other advantages will be readily apparent to those skilled in the art in consideration of this disclosure.

[0055] Detailed descriptions and drawings or figures support and illustrate this disclosure, but the scope of this disclosure is defined solely by the claims. While some of the best modes and other embodiments for carrying out the claimed disclosure have been described in detail, various alternative designs and embodiments exist for carrying out the disclosure as set forth in the appended claims.

[0056] Furthermore, the features of the embodiments shown in the drawings, or the various embodiments described herein, should not necessarily be understood as independent embodiments. Rather, each feature described in one of the examples of an embodiment can be combined with one or more other desired features from other embodiments, making it possible to bring about other embodiments not described in words or by reference to the drawings. Thus, such other embodiments are included within the scope of the appended claims. Furthermore, this disclosure includes the following inventions. The first aspect is, A method for evaluating the stability of the lens capsule in the eye of a human patient, wherein the method is Simultaneously after the eye movement that generates an internal saccade within the eyeball, electromagnetic energy within a predetermined spectrum is guided to the pupil of the eye via an energy source. Acquiring an image of the eye that indicates the eyeball saccade using an image acquisition device, The process involves using the image via an electronic control unit (ECU) to calculate a motion curve describing the movement of the lens capsule, The ECU extracts a time-normalized lens capsule vibration trace based on the motion curve, The time-normalized lens capsule oscillation trace is fitted to the model via the ECU, thereby evaluating the unstable state of the lens capsule. This method includes [something]. The second aspect is, The method in the first embodiment includes calculating the motion curve, a position curve, an instantaneous velocity curve, and / or an acceleration curve. The third aspect is, A second embodiment of the method is a method wherein the electromagnetic energy is light energy, the energy source is a light source, the image acquisition device is a camera, and acquiring an image of the eye includes acquiring an image of the characteristic Purkinje reflection within the eye. The fourth aspect is, The characteristic Purkinje reflect includes a P1 reflect having a P1 coordinate and a P4 reflect having a P4 coordinate, and the method further includes subtracting the P1 coordinate from the P4 coordinate via the ECU, thereby correcting the rotation of the eye, in a third embodiment. The fifth aspect is, A third embodiment of the method is one in which the characteristic Purkinje reflection includes a P1 reflection, and calculating the motion curve includes calculating the motion curve of the P1 reflection. The sixth aspect is, The method in the first embodiment further includes sending a dynamic gaze-guiding cue to a target positioned along the line of sight of the eye, thereby inducing the ocular saccade. The seventh aspect is, The first embodiment of the method involves an image acquisition device being a high-speed camera, and guiding electromagnetic energy in a predetermined spectrum onto the pupil of the eye via the energy source, which includes guiding an infrared (IR) light beam onto the pupil, and acquiring an image of the eye indicating the ocular saccade, which includes guiding the IR light reflected from the eye toward the high-speed camera using a hot mirror. The eighth aspect is, A first embodiment of the method includes guiding electromagnetic energy within a predetermined spectrum onto the pupil of the eye by directly imaging the lens capsule using ultrasonic energy, and acquiring an image of the eye indicating the ocular saccade by collecting an ultrasonic image of the lens capsule. The ninth aspect is, The first embodiment of the method involves applying the aforementioned lens capsule vibration trace to a model, which includes using a concentrated mass model of the saccadic force of the eye. The tenth aspect is, Presenting different accommodation requests to the human patient via an optical lens while acquiring the aforementioned image, The process involves using a nonlinear concentrated mass model to fit the lens capsule vibration trace to the model, It further includes, A method in a first embodiment includes detecting the ciliary muscle activity of the eye in order to diagnose a potential instability of the lens capsule. The eleventh aspect is, An automated system for evaluating the instability of the lens capsule in the eye of a human patient, wherein the system An energy source configured to simultaneously guide electromagnetic energy within a predetermined spectrum onto or into the eye, at the same time as the induced ocular saccade, An image acquisition device configured to acquire an image of the eye indicating the eyeball saccade, An electronic control unit (ECU) that communicates with the energy source and the image acquisition device, The ECU is equipped with, The process involves calculating the motion curve of the lens capsule using the aforementioned image, wherein the motion curve describes the motion of the lens capsule. Based on the aforementioned motion curve, extract a time-normalized lens vibration trace, and The time-normalized lens vibration trace is applied to the model, thereby evaluating the instability state of the lens capsule. It is an automated system configured to perform the following actions. The twelfth aspect is, An automated system in an eleventh embodiment, wherein the electromagnetic energy is light energy, the energy source is a light source, the image acquisition device is a high-speed camera, and the image is of the characteristic Purkinje reflection within the eye. The 13th aspect is, The characteristic Purkinje reflect includes a P1 reflect having a P1 coordinate and a P4 reflect having a P4 coordinate, and the ECU is configured to subtract the P1 coordinate from the P4 coordinate via the ECU, thereby correcting the rotation of the eye, in a twelfth embodiment of the automated system. The 14th aspect is, An automated system in a twelfth embodiment, wherein the characteristic Purkinje reflect includes a P1 reflect, and the ECU is configured to calculate the motion curve of one of the characteristic Purkinje reflects by calculating the instantaneous velocity curve, instantaneous acceleration curve, and / or instantaneous position curve of the P1 reflect. The 15th aspect is, An automated system in an eleventh embodiment, further comprising a visual target, wherein the ECU is configured to send dynamic gaze guidance cues to the visual target to induce the eye saccade. The 16th aspect is, An eleventh embodiment of the automated system, wherein the image acquisition device is a high-speed camera, the electromagnetic energy is an infrared (IR) light beam, and the automated system further comprises a hot mirror configured to guide the IR light reflected from the eye toward the high-speed camera. The 17th aspect is, An automated system in an eleventh embodiment, wherein the energy source and / or the image acquisition device includes an ultrasonic transducer configured to directly image the lens capsule via ultrasonic energy, and the ECU is configured to acquire an image of the eye indicating the ocular saccade by collecting an ultrasonic image of the lens capsule. The 18th aspect is, An automated system in an eleventh embodiment, wherein the ECU is configured to perform the model fitting of the lens vibration trace using a concentrated mass model of the saccadic activating force of the eye. The 19th aspect is, An electronic control unit (ECU) for use with a high-speed video camera when diagnosing instability of the lens capsule in a human patient, wherein the ECU is Processor and A transceiver that communicates with the aforementioned high-speed video camera, The memory in which the instructions are recorded, The processor is equipped with the execution of the instruction by the processor, Receiving an image of the eye from the high-speed camera when infrared (IR) light is guided onto the pupil of the eye, wherein the image includes a P1 characteristic Purkinje reflection. Simultaneously with the characteristic Purkinje reflex, a dynamic gaze induction cue is sent to the target, thereby causing the target to move sufficiently to induce a predetermined eye saccade. Calculating the instantaneous velocity curve, acceleration curve, and / or position curve of the P1 characteristic Purkinje reflex that describes the motion of the lens capsule, Extracting a time-normalized lens vibration trace based on the instantaneous velocity curve, acceleration curve, and / or position curve, and By applying the aforementioned lens vibration trace to the model using a concentrated mass model, the state of the zonule can be diagnosed. This is an electronic control unit (ECU) that performs this function. The 20th aspect is, The transceiver is coupled to an adjustable optical lens positioned along the line of sight between the human patient and the visual target, and the execution of the instruction causes the processor to acquire the image of the characteristic Purkinje reflection while different adjustment requests are presented to the human patient via the adjustable optical lens, in a 19th embodiment of the ECU.

Claims

1. A method for operating an automated system for evaluating the stability of the lens capsule in the eye of a human patient, wherein the operating method is The automated system, using an image acquisition device, acquires an image of the eye indicating an ocular saccade, for an eye in which electromagnetic energy within a predetermined spectrum is guided to the pupil via an energy source simultaneously with the eye movement that generates an ocular saccade inside the eye. The automated system, via an electronic control unit (ECU), calculates a motion curve describing the movement of the lens capsule using the image, The automated system extracts a time-normalized lens capsule vibration trace based on the motion curve via the ECU, The automated system applies the time-normalized lens capsule oscillation trace to the model via the ECU, thereby evaluating the unstable state of the lens capsule. A method of operation including the following.

2. The operating method according to claim 1, wherein the automatic system calculating the motion curve includes the automatic system calculating a position curve, an instantaneous velocity curve, and / or an acceleration curve.

3. The operating method according to claim 2, wherein the image acquisition device is a camera, and the automatic system acquiring an image of the eye includes the automatic system acquiring an image of the characteristic Purkinje reflex within the eye.

4. The operating method according to claim 3, wherein the characteristic Purkinje reflex includes a P1 reflex having a P1 coordinate and a P4 reflex having a P4 coordinate, and the operating method further includes the automatic system subtracting the P1 coordinate from the P4 coordinate via the ECU, thereby correcting the rotation of the eye.

5. The operating method according to claim 3, wherein the characteristic Purkinje reflect includes a P1 reflect, and the calculation of the motion curve by the automatic system includes the calculation of the motion curve of the P1 reflect by the automatic system.

6. The method of operation according to claim 1, further comprising the automatic system sending dynamic gaze guidance cues to targets positioned along the line of sight of the eye, thereby inducing the ocular saccade.

7. The operating method according to claim 1, wherein the image acquisition device is a high-speed camera.

8. The operating method according to claim 1, wherein the automated system acquiring an image of the eye indicating the ocular saccade includes the automated system collecting an ultrasound image of the lens capsule.

9. The operating method according to claim 1, wherein the automatic system fitting the lens capsule vibration trace to a model includes the automatic system using a concentrated mass model of the saccadic force of the eye.

10. The aforementioned operating method, The automated system presents different accommodation requests to the human patient via an optical lens while acquiring the image, The automated system performs the fitting of the model to the lens capsule vibration trace using a nonlinear lumped mass model, It further includes, The operating method according to claim 1, wherein the automated system diagnoses a potential instability of the lens capsule, and the automated system detects the ciliary muscle activity of the eye.

11. An automated system for evaluating the instability of the lens capsule in the eye of a human patient, wherein the automated system An energy source configured to simultaneously guide electromagnetic energy within a predetermined spectrum onto or into the eye, at the same time as the induced ocular saccade, An image acquisition device configured to acquire an image of the eye indicating the eyeball saccade, An electronic control unit (ECU) that communicates with the energy source and the image acquisition device, The ECU is equipped with, The process involves calculating the motion curve of the lens capsule using the aforementioned image, wherein the motion curve describes the motion of the lens capsule. Based on the aforementioned motion curve, extract a time-normalized lens vibration trace, and The time-normalized lens vibration trace is applied to the model, thereby evaluating the instability state of the lens capsule. An automated system configured to perform the following actions.

12. The automated system according to claim 11, wherein the electromagnetic energy is light energy, the energy source is a light source, the image acquisition device is a high-speed camera, and the image is of the characteristic Purkinje reflection in the eye.

13. The automated system according to claim 12, wherein the characteristic Purkinje reflect includes a P1 reflect having a P1 coordinate and a P4 reflect having a P4 coordinate, and the ECU is configured to subtract the P1 coordinate from the P4 coordinate via the ECU, thereby correcting the rotation of the eye.

14. The automated system according to 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 automated system according to claim 11, further comprising a target, wherein the ECU is configured to send dynamic gaze guidance cues to the target and induce the eye saccade.

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