Fitting system for an implantable lens

Abstract

The present disclosure includes an imaging system and a method for operating the imaging system. The method includes generating an estimate of a position of a PIOL that corrects a vision deficiency in a patient's eye, the PIOL having a particular size, from anatomical parameters describing the patient's eye, and generating a three-dimensional graphical representation of a distance between a posterior surface of the PIOL and a lens of the patient's eye and displaying the three-dimensional graphical representation on a display controlled by the imaging system.

Description

background

[0001] For some patients seeking to reduce their reliance on glasses and / or contact lenses, phakic intraocular lenses (PIOLs) (such as implantable collagen polymer lenses) are an attractive alternative. A PIOL is surgically inserted between the patient's lens and iris. The height of the posterior portion of the PIOL from the plane of the footplate is called the "lens vault," while the distance between the posterior portion of the PIOL and the anterior surface of the patient's lens is called the "lens separation," but in ophthalmology it is often simply referred to as the PIOL "vault." Choosing the correct size for a PIOL presents significant challenges. Problems can arise if the implanted PIOL is too large (resulting in a very high vault) or too small (resulting in a very low vault or no vault).

[0002] If the implanted PIOL is too large and creates an excessively high vault, it may push the iris forward. This can lead to narrowing of the anterior chamber angle, potentially increasing the risk of intraocular pressure changes and subsequent irreversible glaucoma nerve damage. Furthermore, the posterior surface of the iris, the pigment epithelium, may be excessively rubbed / abraded by an oversized PIOL, causing iris pigment to be rubbed away and dispersed into the anterior chamber. Unwanted pigment cells in the anterior chamber can affect the trabecular meshwork, leading to increased fluid outflow resistance, increased intraocular pressure, and glaucoma nerve damage.

[0003] If the implanted PIOL is too small and produces too low an arch, it may come into contact with the anterior surface of the lens. This could lead to early cataract formation. Furthermore, if the PIOL's arch is too low (even if it doesn't contact the anterior surface of the lens), it may interfere with the flow of nutrients to the lens, which could also contribute to early cataract formation. Finally, the lens may increase in size over time, and therefore, sufficient space must be provided between the PIOL and the lens surface to allow for lens growth.

[0004] It would be advantageous to provide the surgeon with a detailed diagram of the spacing between the PIOL and the lens for each possible PIOL size for the desired vision correction of a specific patient who may be considering surgery. Overview

[0005] This disclosure includes a method for operating an imaging system and an imaging system. The method includes: generating an estimate of the location of a PIOL (Portable Eye Orifice) based on anatomical parameters describing a patient's eye, the PIOL correcting a visual defect in the patient's eye, the PIOL having a specific size; and generating a three-dimensional graphical representation of the distance between the posterior surface of the PIOL and the lens of the patient's eye, and displaying the three-dimensional graphical representation on a display controlled by the imaging system.

[0006] In one aspect, anatomical parameters are measured using imaging systems.

[0007] On the other hand, the imaging system is an ultrasound imaging system suitable for scanning a patient's eyes.

[0008] On the other hand, the method is repeated for PIOLs of different sizes.

[0009] In another aspect, the method includes generating a cross-sectional view of the patient's eye, which shows the estimated location of the PIOL and the surface of the patient's lens.

[0010] In another aspect, the method includes generating a cross-sectional view of the patient's eye that shows the estimated location of the PIOL, as well as the movement of the iris position and the reduction of the anterior chamber angle.

[0011] The imaging system according to this disclosure includes a measuring component, a display, and a controller adapted to use the measuring component to measure anatomical parameters describing a patient's eye, to generate an estimate of the location of a PIOL of a specific size (which corrects visual defects in the patient's eye) based on the anatomical parameters, and to generate a three-dimensional graphic representation of the distance between the posterior surface of the PIOL and the lens of the patient's eye, and to display the three-dimensional graphic representation on the display.

[0012] In one aspect, the measuring components include an ultrasound imaging system suitable for scanning a patient's eyes.

[0013] On another front, the controller generates three-dimensional graphical representations with multiple different PIOL sizes.

[0014] In another aspect, the controller generates a cross-sectional view of the patient's eye, which shows the estimated location of the PIOL and the surface of the patient's lens.

[0015] In another aspect, the cross-sectional view also includes an estimated position of the iris of the patient's eye after the PIOL has been implanted. Brief description of the attached diagram

[0016] Figure 1 This is a cross-sectional view of a portion of the eye, showing the structures associated with the PIOL implant.

[0017] Figure 2 This shows what happens after inserting PIOL 21. Figure 1 The area of ​​the eye shown.

[0018] Figure 3 This is a top view of the PIOL 21.

[0019] Figure 4 An exemplary 3D display is shown, which provides details of the projected fit of the PIOL to the patient's eye.

[0020] Figure 5 An embodiment of an imaging system according to the present disclosure is shown.

[0021] Figure 6 A top view of the PIOL 61 that has been implanted in the eye 62 is shown.

[0022] Figure 7 The parameters measured using ultrasound or other scanners are shown.

[0023] Figures 8A-8E illustrate how the posterior chamber size arch height changes with compression due to the increase of PIOL in the posterior chamber. Detailed description

[0024] refer to Figure 1 This makes it easier to understand how the invention provides its advantages. Figure 1 This is a cross-sectional view of a portion of the eye, showing the structures associated with the PIOL implant. The cornea is shown at 11. The superior surface of the capsule that houses the lens is shown at 13. The iris is shown at 12. The angle between the iris and the inner surface of the cornea is shown at 16. The ciliary body is shown at 14. The ciliary sulcus is shown at 15.

[0025] Now for reference Figure 2 It shows what happens after inserting PIOL 21. Figure 1 The area of ​​the eye shown. The PIOL is inserted between the lens and iris 12. The foot of the PIOL is located in the area of ​​the suspensory ligaments, ciliary body, or ciliary sulcus, but preferably at or near the lower part of the ciliary sulcus. The PIOL 21 is arched above the lens capsule 13, as shown at 20. Therefore, the length of the iris surface rotates upward toward the cornea around its root. This results in a decrease in the angle 16 at the root, as shown at 16'. The greater the arch height 20, the smaller the angle 16 becomes. Furthermore, the posterior surface of the iris 12 in contact with the PIOL 21 may rub in a manner that causes pigment to be released from the iris. The higher the arch height, the greater the abrasive force that may cause this release.

[0026] Now for reference Figure 3 This is a top view of PIOL 21. PIOL 21 includes a central region 22 in which the lens is located and supporting regions (haptic or "legs" 24 on each side of region 22). The supporting regions terminate at two or more footplate feet shown at 23. Footplate feet 23 press against the suspensory ligaments, ciliary body, or ciliary sulcus 15 and stabilize PIOL 21 in place. The material constituting PIOL 21 is flexible. Typically, the length of PIOL 21 is greater than the distance between the ciliary body and the ciliary sulcus point where PIOL 21 is located, and therefore, PIOL 21 is essentially spring-loaded into place. The lens prescription is proportional to the thickness distribution of the lens, and therefore proportional to the stiffness and mechanical properties of the lens. The amount of force applied to the feet depends on the specific lens prescription, the arch height 20, and the material used to make the insert. If insufficient force is applied to push the foot into the ciliary sulcus, the PIOL may shift after implantation due to the physical force exerted on the patient's eye. If the lens shifts, it may deviate from its central position or rotate within the posterior chamber, resulting in optical distortion due to higher-order aberrations in the visual pathway, such as tilt aberration, coma, and astigmatism.

[0027] Preoperative patient examination for implant preparation is preferably performed using a high-frequency ultrasound scanner. Ultrasound scanners are superior to optical methods because they can observe the physical properties of the patient's eye, which is covered by an opaque iris and therefore cannot be directly observed through optical devices. Optical devices (e.g., optical coherence tomography) can typically image a portion of the posterior chamber within the area exposed by the pupillary opening. If the pupil is dilated, a larger portion of the posterior chamber can be imaged by such an optical device, encompassing the anterior and posterior surfaces of the lens within the dilated pupillary aperture. The curvature of the anterior and posterior surfaces can be mathematically extrapolated to estimate the size of the posterior chamber, but direct visualization and measurement of the posterior chamber behind the iris is best achieved adequately with ultrasound. Lower wavelength optical coherence tomography can penetrate behind the iris and allow imaging of this area. Lower wavelength optical coherence tomography results in higher thermal effects during scanning of biological tissue and may be limited when penetrating the iris. However, the posterior chamber anatomy and geometry can be imaged using optical devices.

[0028] In one aspect of the invention, a physician scans a patient’s eye using ultrasound or another imaging system, and a software package on the imaging system generates a three-dimensional map of the predicted distance between the PIOL and the top surface of the patient’s lens capsule, based on the location of each of a plurality of different-sized PIOLs available for the patient.

[0029] Now for reference Figure 4 , Figure 4 An exemplary three-dimensional display is shown, providing details of the projection fit of the PIOL to the patient's eye. The display includes the projected position of the PIOL 52 within the patient's eye 51. An exemplary distance between the PIOL and the capsule is provided, as shown at 53. Furthermore, regions within the PIOL are encoded to indicate the distance between the PIOL and the capsule at each point. The encoding can be either shading (where dark colors indicate depth) or color (where different colors indicate different distances) to provide a third dimension.

[0030] On another front, the software also provides the user with a cross-sectional view of the patient's eye, showing the expected projection position and changes when the PIOL is inserted. This display is similar to... Figure 2 The display shown illustrates variations such as the arch height 20 of the PIOL above the lens and the anterior chamber angle 16, the details of which will not be discussed further in this article.

[0031] Typically, a variety of different lens sizes are available. Furthermore, the mechanical properties of the lens depend on the type of vision correction prescription and the degree of lens compression when inserted between the zonular, suspensory ligament, or ciliary sulcus boundaries. For each lens size, this invention uses measured distances between posterior chamber dimensions and the lens's mechanical properties to predict the three-dimensional configuration of the implanted lens when placed between the zonular, ciliary, or ciliary sulcus points. Based on this configuration and measurements of the patient's natural lens surface, the imaging system generates a map of the calculated predicted modeling distance between the implanted lens and the patient's lens. Additionally, the imaging system generates a representation of how the PIOL's vault propels the iris forward, and thus, based on the force exerted by the PIOL due to its properties when fitted to the posterior chamber of the eye and the PIOL's compression, generates a representation of how the PIOL's vault narrows the angle of that particular eye. The imaging system also generates a representation of where the PIOL foot will be pressed (whether it's pressed on the suspensory ligament area, the ciliary body area, or the ciliary sulcus area). The physician can then select the best predictive fit for the patient.

[0032] In another aspect of the invention, the patient's eye is scanned postoperatively using ultrasound or other imaging techniques to determine the achieved posterior chamber relationship between the PIOL and the eye's anatomy, and to determine whether the implanted lens is correctly positioned and conforms to the predicted or clinically acceptable configuration. Ideally, all PIOL feet contact the ciliary body and ciliary sulcus, such that the lower surface of the PIOL lens is separated from the patient's own lens, and the lens axis corrects astigmatism. If not all feet are correctly positioned, the plane of the PIOL may be tilted. Furthermore, in the case of a tortuous PIOL, the lens orientation relative to the cornea must also be correct. If these types of problems are detected in the post-implantation scan, the lens position can be adjusted without removing the PIOL, compared to exchanging the lens under the assumption of correct positioning and incorrect lens size (a much riskier procedure).

[0033] During ultrasound or other scans, the patient's eyes must be still so that the results from various scan lines can be combined. Therefore, it is advantageous to provide a scan mode that requires a minimum number of scan lines to adequately obtain measurements of the PIOL's central position and axis orientation. Now refer to... Figure 6 The image shows a top view of the PIOL 61 implanted in eye 62. To locate the edge of the PIOL, a scan is performed along lines 71-74, identifying six points along the edge of the PIOL 61, as shown at points 63-68. These six points are used to calculate the long axis orientation of the PIOL, and thus the orientation to be calculated for two scans passing through the foot, as shown at points 75 and 76. Next, two scans are performed along lines 75 and 76 (along the axis of the foot) to determine the position of the foot of the PIOL 61 within the posterior chamber. If the feet are not at the same height, the position of the PIOL 61 may need to be changed because the PIOL 61 is tilted. Similarly, if the axis of the line passing through points 63-64 is not parallel to line 72, and the PIOL 61 is a toric lens, the PIOL 61 may need to be rotated around the intersection of lines 72 and 74 to adjust for astigmatism correction.

[0034] As described above, this invention relies on the ability to predict the morphology of the implanted PIOL prior to implantation. The measured parameters include anatomical measurements obtained using ultrasound or other scanners and the scleral pupil diameter (SPD). Now refer to... Figure 7 It shows the parameters measured using an ultrasound scanner. It should be noted that the eye is relatively spherical, and therefore, many structures are morphologically circular or elliptical.

[0035] A readily identifiable "landmark" is the ciliary sulcus. A plane 35 through the ciliary sulcus is used to define the three measurements of interest. The distance from ciliary sulcus to ciliary sulcus (STS) is shown at 34. This is essentially the diameter of the ciliary sulcus ring in the area where the PIOL will be implanted. The maximum distance 32 from the plane defined by the ciliary sulcus to the anterior margin of the cornea will be called the STSL. The distance 31 from the cornea to the anterior part of the cornea will be called the anterior chamber depth (ACD). The diameter 33 of the plane passing through the ciliary body (where the dome is furthest inward) is called the internal diameter of the ciliary body, or CBID, and this is also predictive.

[0036] Besides relying on parameters related to imaging behind the iris, SPD has been found to have predictive value in determining the pivot height or finding the lens size that provides the desired pivot height. SPD is the diameter of the pupil under scotopic light conditions, and it is related to the pivot height due to the difference in the force exerted by the iris on the PIOL for small and large pupils under physiological conditions. Pupil size varies with illumination conditions, causing the pupil to constrict in bright light and dilate in dim light. Therefore, pupil size will vary depending on illumination conditions and how illumination changes during the day, producing specific variations in the distance between the pivot and the lens. Scotopic pupil size is defined as the pupil diameter under scotopic illumination conditions (defined as ambient 0.04 lux). Other definitions of scotopic illumination conditions exist, and these can be extended to predict the pivot fit. Furthermore, lens size and pivot power need to be taken into account. Lens size is the diagonal diameter of the lens to the haptic tip. Recommended PIOL lens sizes are provided by the lens manufacturer. The PIOL power is related to the curvature of the inner and outer surfaces of the PIOL's optical center. For example, a high-power myopic lens will have an increased radius of curvature on the posterior surface of the lens compared to a lower-powered lens, resulting in a higher central occlusion. The PIOL power is also related to the PIOL's thickness distribution, and therefore, PIOLs with different powers will respond differently when force is applied. Thus, PIOLs with different powers (assuming all other conditions are equal) will result in different occlusion outcomes.

[0037] In the following discussion, the parameters CBID, SPD, STS, and STSL will be referred to as anatomical parameters. The parameters PIOL degree and PIOL size will be referred to as target PIOL parameters.

[0038] In one aspect of the invention, a model dependent on anatomical parameters, target PIOL parameters, and a set of unknown parameters is trained by fitting a dataset obtained by measuring multiple different patients before and after PIOL implantation. In the training mode, existing technology systems for predicting arch height are utilized to minimize the risk of implanting an improperly sized PIOL into the patient. Once a dataset with sufficient statistical accuracy to provide improved accuracy is accumulated, improvements usable with this system can be implemented.

[0039] An exemplary model relates the piol's arch height to a linear function of the aforementioned parameters, for example:

[0040] Predicted arch height = a*CBID + b*STSL + c*(PIOL degree) + d*(PIOL dimension) + e*SPD

[0041] The parameter ae was determined by fitting the arch height values ​​observed in the patient group.

[0042] The linear model described above is merely an exemplary model that can be used to model the dependence of arch height on anatomical parameters. For example, nonlinear models (such as polynomial, exponential, expert parameter cost center weighted systems, or neural networks) can be trained to provide arch height predictions.

[0043] Now for reference Figure 5 This illustrates one embodiment of an imaging system according to the present disclosure. In system 40, the imaging apparatus uses ultrasound or other imaging equipment 42 coupled to the patient's eye via a patient interface 41 to form an image of the patient's eye. The recorded images are processed by a controller 43, which extracts anatomical measurements dependent on the ultrasound or other images. A user interface 44 allows the user to input additional information (e.g., PIOL power and possible dimensions) to the controller 43. The controller 43 calculates the predicted arch height for each lens size requested by the user. A three-dimensional map of the distance between the lens capsule and the predicted PIOL configuration is then displayed on a display 45.

[0044] As described above, the data processing function of controller 43 can be implemented on a separate data processing system adapted to receive ultrasound images or other images from a separate ultrasound imaging device or other imaging device. The user interface of this separate data processing system can be used to input lens characteristics and output the predicted arch height for each desired lens size.

[0045] On another front, the fitting system according to the invention provides a warning if a physician attempts to achieve an arch height beyond the predetermined range by using a large PIOL in an eye with an excessively small internal posterior chamber size. Referring now to Figures 8A-8E, which illustrate how the arch height varies with CBID and posterior chamber size. Each figure shows a cross-section of a PIOL implanted in an eye with a specific CBID and posterior chamber size. The “foot” of the PIOL is shown at 81 in Figure 8A. The region 82 between the foot and the lens is generally referred to as the haptic of the lens, but will be referred to as the leg in the following discussion. Assume the arch height of the configuration shown in Figure 8A is V. Within the useful range of the PIOL, the leg concaves upwards, as shown in Figure 8A. The arch height increases when the feet are brought closer together (i.e., the lens is placed in a smaller eye). The amount of increase in the specific variation x of the spacing will be referred to as “a”. The arch height for the variation x between the configurations shown in Figures 8A and 8B is approximately V+a, as shown in Figure 8B. If, according to x, the feet are brought even closer (i.e., even smaller eyes), the arch height increases predictably to approximately V+2a based on the specific mechanics of PIOL, as shown in Figure 8C. Similarly, by bringing the feet closer together by the same amount, the arch height can increase to V+3a, as shown in Figure 8D. It should be noted that as the arch height increases by the amount shown in Figures 8A-8D, the legs remain concave upwards.

[0046] Essentially, a physician might want to implant an implant with a very high vault (having dimensions including a very high STSL) into the eye, and in principle, use a larger lens, which would force its legs closer together compared to a smaller lens. This type of fit might be better suited to younger patients to allow more room for the natural lens to grow with age. However, experiments have shown that the ability to increase vault by increasing the size of the PIOL is limited. At some point, the legs of the PIOL become concave, as shown in Figure 8E, and based on the relationship described above between the vault V and the relative approximation x, the vault “jumps” by a much higher increment than expected. This secondary mechanical behavior of the PIOL will result in excessively high vault values. For example, instead of obtaining a vault of V+4a if approximated by 4x, the implant might have a vault of V+6a when inserted into a patient's eye (even if a vault of 4a is predicted), which would be excessive. In such cases, explantation and / or replacement of the PIOL may be necessary. As mentioned above, such exchanges are generally to be avoided because they involve further risks to eye health.

[0047] The point at which the leg configuration changes from an upward concave to a downward concave will be called the inversion point. The inversion point is a function of the specific PIOL material, size, and prescription. In one aspect of the invention, the operating system warns the physician of the possibility of inversion for each PIOL size approaching the inversion point of a patient being treated. The cross-sectional display discussed above can also illustrate inverted versions of the PIOL and excessive arch height.

[0048] The invention also includes a computer-readable medium storing instructions that cause a data processing system to perform the methods of the invention. A computer-readable medium is defined as any medium that constitutes the patentable subject matter of 35 USC 101, but excludes any medium that does not constitute the patentable subject matter of 35 USC 101. Examples of such media include non-transitory media, such as computer memory devices that store information in a format readable by a computer or data processing system.

[0049] The foregoing embodiments of the invention have been provided to illustrate various aspects of the invention. However, it should be understood that different aspects of the invention shown in different specific embodiments can be combined to provide other embodiments of the invention. Furthermore, various modifications to the invention will become apparent from the foregoing description and drawings. Therefore, the invention is limited to the scope of the appended claims.

Claims

1. A method for operating an imaging system, the method comprising: An estimate of the location of a PIOL in a patient's eye, the PIOL correcting visual impairment in the patient's eye, the PIOL having an anterior surface, a posterior surface, a size, and a power, the location estimate including an estimate of the vault height, which is the distance between the anterior surface of the lens of the patient's eye and the posterior surface of the PIOL, and including: The imaging system receives multiple anatomical parameters describing the patient's eye, wherein the multiple anatomical parameters include CBID; and The estimated arch height value is calculated using a model comprising: the estimated arch height value = a*CBID + b*STSL + c*(PIOL degree) + d*(PIOL size) + e*SPD, where a*e is a parameter determined by fitting arch height values ​​observed in the patient group, CBID is the diameter of the plane at the furthest inward arch of the ciliary body, STSL is the maximum distance from the plane defined by the ciliary sulcus to the anterior margin of the capsular capsule, and SPD is the diameter of the pupil under dim light conditions. A three-dimensional graphical representation of the estimated arch height value is generated and displayed on a display controlled by the imaging system.

2. The method of claim 1, wherein, The anatomical parameters are measured by the imaging system.

3. The method of claim 1, wherein, The imaging system is an ultrasound imaging system suitable for scanning a patient's eyes.

4. The method according to claim 1, wherein, Repeat the above method for PIOLs of different sizes.

5. The method of claim 1, further comprising generating a cross-sectional view of the patient's eye, the cross-sectional view showing the estimated location of the PIOL and the anterior surface of the patient's lens.

6. The method according to claim 5, wherein, The cross-sectional view also includes an estimated position of the iris of the patient's eye after the PIOL has been implanted.

7. An imaging system, comprising: Measurement components; monitor; and controller, The controller is adapted to: The measurement component is used to measure multiple anatomical parameters describing a patient's eye, wherein the multiple anatomical parameters include CBID. An estimate of the location of a PIOL (pivot artery) for correcting visual impairment in the patient's eye is generated based on the anatomical parameters. The PIOL has an anterior surface, a posterior surface, a size, and a power. The location estimate includes an estimate of the arch height, which is the distance between the anterior surface of the patient's lens and the posterior surface of the PIOL. The estimated arch height value is calculated using a model comprising: the estimated arch height value = a*CBID + b*STSL + c*(PIOL degree) + d*(PIOL size) + e*SPD, where a*e is a parameter determined by fitting arch height values ​​observed in the patient group, CBID is the diameter of the plane at the furthest inward arch of the ciliary body, STSL is the maximum distance from the plane defined by the ciliary sulcus to the anterior margin of the capsular capsule, and SPD is the diameter of the pupil under dim light conditions. A three-dimensional graphical representation of the estimated arch height value is generated and displayed on the display.

8. The imaging system according to claim 7, wherein, The measurement components include an ultrasound imaging system suitable for scanning a patient's eyes.

9. The imaging system according to claim 7, wherein, The controller generates the three-dimensional graphical representation for multiple different PIOL sizes.

10. The imaging system according to claim 7, wherein, The controller generates a cross-sectional view of the patient's eye, which shows the estimated location of the PIOL and the anterior surface of the patient's lens.

11. The imaging system according to claim 10, wherein, The cross-sectional view also includes an estimated position of the iris of the patient's eye after the PIOL has been implanted.

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