METHOD AND DEVICE FOR ELABORATING THE SIZE OF AN INTRAOCULAR PHAK IMPLANT FOR THE CORRECTION OF REFLECTIVE VISION

Abstract

The invention relates to a method and device for developing the size of a phakic vision correction implant for the eye (3) of a patient. From a horizontal section (6) of the anterior segment of the eye and an optical power Po, we determine (34) the size of several implants from a basis Ii, we geometrically simulate (35) the image of the respective positions of these implants on reconstructed surfaces s1, s2, ...si of the section, then we calculate (37) for each size of implant Ii, the value Vtsci of the theoretical Vault without compression and the total theoretical compression CTi, we calculate (42) the probability of obtaining a satisfactory Vault between two threshold values ​​S1 and S2 by considering the cases of operated patients for whom the respective differences between their Vtsci and the postoperative Vaults for a given compression CTi have been calculated, and we choose (43) the size of implant presenting the highest probability between S1 and S2.Figure for the abridged version: Fig. 1.

Description

Title of the invention: METHOD AND DEVICE FOR ELABORATING THE SIZE OF AN INTRAOCULAR PHAK IMPLANT FOR THE CORRECTION OF AMETROPIES

[0001] The present invention relates to a method for developing the size of a phakic vision correction implant for a patient's eye and more particularly of an intraocular phakic implant (IIP) for the correction of ametropias (such as myopia, hyperopia and astigmatism).

[0002] It allows a distance between the implant and the patient's lens to be obtained which significantly limits the risks of subsequent complications.

[0003] It also relates to a device implementing such a development process.

[0004] It finds a particularly important, although not exclusive, application in the field of eye surgery allowing the correction of vision defects observed in implanted patients, particularly between 18 and 60 years of age, between the natural lens and the patient's iris often posing reliability problems.

[0005] There are known methods which seek to predict the distance between the posterior face of the implant and the anterior face of the natural lens, called vault (in Anglo-Saxon terminology) and hereafter referred to as Vault, in order to determine the size of the optimum phakic intraocular lens which should allow the effective correction of a patient's vision while limiting postoperative complications.

[0006] Such predictive processes or models are based on encrypted biometric measurements of the eye of the patients concerned and have several drawbacks.

[0007] First, they exhibit a precision that depends on the sample (size, representativeness) on which the model is developed. For example, it is observed that the model's performance depends on the patient's ethnicity, with the algorithmic formulas used performing better on patients of the same ethnicity as those used to develop the model.

[0008] They depend on the devices used to perform biometric measurements on patients.

[0009] Indeed, the biometric parameters used can vary from one machine to another, thus requiring the development of a new model and a new algorithm corresponding to each device.

[0010] It is observed that the algorithms of prior art models produce results that do not take into account the margins of error inherent in said models. models, and also do not allow surgeons to assess the reliability of these results.

[0011] They do not allow for the effective dissociation of the lateral compression phenomenon of the implant from the suitability of the patient's anatomy to the implant geometry, thus leading to a tendency to overestimate small Vaults and underestimate large Vaults. Furthermore, they are less able to properly address the specific cases of certain atypical patients. A small Vault is defined as a dimension (height) less than 200 microns, and a large Vault as a dimension greater than 850 microns.

[0012] The present invention aims to provide a method and device for developing the optimal size of a phakic corrective implant that better meets the requirements of practice than those previously known, in particular in that it will allow the dissociation of the phenomenon of horizontal compression of the implant by the walls of the eye, from that of the adequacy between the patient's anatomy and the geometry of the implant, in that it allows the use of the patient's structures directly in contact with the implant, which will make it possible to avoid deformations leading to troublesome postoperative constraints, in that it offers a solution independent of considerations related to the ethnicity of the patients who were used to develop the model and / or that of the patients treated, the solution being independent of the imaging machines used, and allowing the surgeon to take into account the margin of error of the model, the uncertainties that it could generate,and all this while producing a result that is visually interpretable by the latter.

[0013] Indeed, by using numerical parameters, older methods make approximations about the structures actually in contact with the implant. These approximations differ from one ethnic group to another. By actually detecting the structures involved (namely those corresponding to the iris, the lens, and the ciliary body, as well as its interparietal portion), the invention eliminates these approximations.

[0014] With the invention it is possible to almost completely eliminate defects related to errors in the geometry of the implant by detecting the structures that will serve as support and mechanical constraints for the implant, to accurately simulate the positioning of the implant in the eye, and this while taking into account the margin of error and uncertainty related to compression, which the known processes of the prior art did not do sufficiently.

[0015] More specifically, in the embodiment described herein, almost all structures in direct contact with or in the immediate vicinity of the implant are detected directly. The only part modeled is then the non-visible portion between the lens and the ciliary body.

[0016] This small portion, modeled by a polynomial function, has a regular shape which turns out to be very well represented by this function.

[0017] The uncertainty in this area is low. The rest is actually detected. Furthermore, by knowing the exact geometries of all potential implants from the outset and integrating them into the development process, certain errors of older methods related to a mismatch between the geometry of the implant and the anatomy of the eye are avoided.

[0018] This results in a sharp increase in the reliability and success rate of surgical operations without deleterious postoperative effects causing the need for reoperation.

[0019] With the present invention, in addition to the gain in quality of the result linked to the choice of the appropriate implant, greater ease of placement by the surgeon is obtained due to the excellent dimensioning.

[0020] To this end, the invention proposes in particular a method for elaborating the size of a phakic corrective implant for the vision of a patient's eye by a user - wherein a raw image of a horizontal section of the anterior segment of the patient's eye is obtained, - from the said raw image on the one hand and an optical power Po of the implant determined beforehand, for example by a subjective examination of the refraction in a manner known in itself by an ophthalmologist, on the other hand, - the structures corresponding to the iris I, the lens L, and the intra-parietal portion M of the ciliary bodies C are identified in the image, - We determine the angle between a line X separating the outermost points A of the iris I and a horizontal line H (corresponding to the horizontal line of the image), - we perform a rotation to make these two lines X and H coincide, - we detect four series of points, namely O the said two points A, substantially symmetrical with respect to the lens, formed by the outermost points of the iris I on the image, O two points B, substantially symmetrical with respect to the lens, formed by the innermost points on the image of the ciliary body C, Two points D, substantially symmetrical with respect to the lens, corresponding to the connection between the ciliary body C and its intraparietal portion M, and a series of points E located on the anterior face F of the lens L, are used to calculate, from these points, at least two versions of the surface, called reconstructed surfaces (si, s2, ... si), on which the implant is planned to be placed, using a polynomial function. The geometry or size of a first implant II is determined from the determined optical power Po and from the geometric characteristics of implant II present in a specific implant database, hereinafter also referred to as the database. Supplier data, we geometrically simulate the image of the respective positions of implant II on the said reconstructed surfaces if, s2, ...if, - from the image of these respective positions, we calculate the Vti value of the theoretical Vault without compression for each reconstructed surface, if, s2,..., if, the theoretical or simulated Vault without compression, Vtscl retained from implant II, being the average of said Vti values ​​obtained for said reconstructed surfaces, - We repeat the calculations of theoretical Vault without compression Vtsci for each implant size li presenting the same optical power Po existing in said implant database, - For each implant li, the total theoretical compression CTi is calculated, defined as the difference between the size of the implant li and the distance between the two points A. - For each implant li, and based on its theoretical or simulated Vault without compression Vtsci, its total theoretical compression CTi, and a database of operated patients (hereinafter also referred to as the Patients database) for which the respective differences between their theoretical Vault without compression and the postoperative Vaults actually obtained with said respective patients, as well as their total theoretical compressions, have been calculated, the probability of obtaining a satisfactory Vault between two threshold values ​​S1 and S2 is calculated from the Patients database, considering the cases of patients in the database having a determined total theoretical compression CTi.and we choose the implant size with the highest probability of being within this range between these two threshold values ​​SI and S2.

[0021] By two points substantially symmetrical with respect to the crystalline lens, we mean two points symmetrical in the plane of section used with respect to a vertical axis of the crystalline lens which is coincident or as close as possible geometrically to what its axis would be if the crystalline lens formed a perfectly regular body or polygon, to within several tens of microns, for example < 100 or 50 microns.

[0022] By size we mean the total overall diameter of the implant seen from above, that is to say of the circle in which said implant is inscribed.

[0023] By raw image we mean the grey level image obtained for example by optical coherence tomography, or obtained, in a non-limiting way, by high frequency or very high frequency ultrasound UBM (Anglo-Saxon initials for "Ultrasound Biomicroscopy") an imaging technique which allows visualization of the internal structures of the eye (iris, ciliary body,...) with excellent resolution.

[0024] The geometric simulation of the image of the position of the implant on the reconstructed surface is described more precisely below in an embodiment given by way of non-limiting example.

[0025] The implant databases used are those of companies in the market such as the American company STAAR Surgical.

[0026] The identification on the image of the structures corresponding to the iris, etc.... is done in a way known in itself, for example by use of a "deep learning" segmentation model, such as for example and in no way limiting the convolutional neural network known as UNet from the University of Freiburg (Germany), which was trained on manually labeled images.

[0027] Rotations are for example performed by code in python using existing libraries.

[0028] The points E are variables, automatically detected in a known way, for example by being spaced at the same determined length, for example a few microns, for example between 10 microns and 50 microns... knowing that in practice one could take all the points of the anterior face F of the lens L.

[0029] The polynomial function is, for example, a fourth-degree polynomial whose coefficients vary from one image to another and are adjusted with respect to the points in a manner chosen by a person skilled in the art, for example, by the least squares method. The invention thus makes it possible to take into account the margin of error and uncertainty related to compression from a database of operated patients and to perform a probability calculation that will make it possible to obtain a Vault considered satisfactory (for example, in the range between 250 and 750 microns) by taking into account the (more or less satisfactory) results obtained with implants actually placed on patients, thanks to a combination of the theoretical Vault without compression with an estimate (by calculation) of the total theoretical compression CTi (horizontal) of the implant.

[0030] Another range may be chosen, for example between 300 and 800 microns, or 200 and 700 microns or between 100 and 500 microns.

[0031] With the process according to the embodiment of the invention more particularly described here, two steps are therefore particularly important.

[0032] The first concerns the compilation of information regarding the data of operated patients, which will be stored in a structured database called the Patient database. This is a dynamic database, as it is fully configurable and modifiable according to, for example, a simple architecture.

[0033] This is, for example, a table with two columns and N rows, where N is the number of patients (i.e., patients' eyes, since patients often have a record for each of their two eyes) in the database. The first column is the difference between the simulated Vault without compression and the obtained Vault. The second column, called "comp_max" and corresponding to the CTi, is the difference between the size of the implant and the distance between the two points A.

[0034] The Patient database uses, on the one hand, the difference between the implant size and the distance between the two horizontal walls (points A) in contact with the implant (therefore independent of ethnicity), and on the other hand, the difference between the calculated (predicted) Vault without compression and the obtained Vault. This difference incorporates the prediction errors of the Vault without compression and the errors related to compression.

[0035] The errors of the uncompressed Vault are indeed related to the detection of structures and the modeling of the surface by the polynomial function. These elements are therefore independent of ethnicity and depend on the imaging capabilities of the measuring machine.

[0036] Indeed, errors related to compression are linked to the capacity of the implant to absorb compression.

[0037] This capacity can be broken down into two components: one related to the implant itself, which has a design that allows it to absorb some of the compression (independent of ethnicity), and the other related to the patient's anatomy, which can absorb more or less compression. Since the various possible anatomies exist in all ethnicities, risk thresholds can then be objectively determined from the patient database. These thresholds are, in fact, fixed.

[0038] In one embodiment, the risk thresholds are developed for example as follows: the Patient database is separated into three categories according to the variable "size_diff", that is to say, according to the extent of the differences observed between the theoretical Vault without compression and the Vault actually obtained in the operated patient.

[0039] The low-risk category has the smallest range of difference values. (Vault obtained close to the simulated Vault without compression). These patients correspond to uncompressed or substantially uncompressed implants.

[0040] The high-risk category, on the other hand, exhibits the widest range of difference values ​​(the obtained Vault is highly variable compared to the simulated Vault). These are patients with strong horizontal compression that is more or less absorbed.

[0041] The moderate risk category lies between the two categories specified above, and this is the one that is generally of interest. However, in some cases, it may be necessary for the implant to be either not compressed at all or, conversely, only slightly compressed to obtain the desired vault, depending on the patient's anatomy.

[0042] The categories therefore come from the size_diff variable (or total compression).

[0043] For example, in one embodiment it will be considered that there is a low risk if size_diff < 0.5 mm, a moderate risk if size_diff is located between 0.5 and 1 mm, and a high risk if size_diff > 1 mm.

[0044] The second step consists of implementing an algorithm using, on the one hand, commercial CAD / CAM software, for example written in Python using open-source libraries for mathematics, image analysis, and deep learning (in a non- limiting and for example known under the names SciPy, Scikit-Image, PyTorch Pandas, Numpy or Matplotlib) allowing to perform the measurements of the structures of the image, to apply the rotations, the determination of the series of points and the calculations of the reconstructed surfaces, and on the other hand a specific software allowing the simulation of the positions of the implants chosen in the Supplier databases, allowing the calculation of the theoretical Vaults without compression.

[0045] According to the embodiment of the invention described more particularly herein, the specific algorithm or software is developed to fulfill the following functionalities: - Reconstruction of the support surface using the polynomial function; - Determination of the y coordinates of the support surface for the positions xl and x2 corresponding to each of the points of application of the effective compression of the implant centered horizontally with respect to the central axis of the lens.

[0046] These elements can be easily programmed by a person skilled in the art, an ophthalmologist with a minimum of computer knowledge and / or combined with a computer scientist and thus makes it possible to obtain the theoretical Vault without compression.

[0047] For example, the reconstruction of the surface to simulate the position is the curve formed by each value of x of the maximum between the polynomial function f(x) and the highest point of the ciliary body.

[0048] Such a process is therefore independent of measurement methods.

[0049] In the event of a change in the Supplier databases, the method remains consistent and will allow the positioning to be simulated in the same way.

[0050] The Patients database will be adapted or modified (if necessary) to be consistent with the use of competing implants in the new (different) Suppliers database.

[0051] In advantageous embodiments, one and / or moreover, one and / or the other of the following provisions are also used: - as indicated above, the Patient database is separated into three risk categories Gi based on the extent of the differences observed between the theoretical Vault without compression and the Vault obtained after the patient's operation, namely a low risk category G1 defined by a total theoretical compression Cti less than a first threshold Sri, has the smallest range of difference values, a high risk category G2 defined by a total theoretical compression Cti greater than a second threshold Sr2 has the widest range of difference values ​​and a moderate risk category G3 located between the two previous categories Sri is for example chosen between 0.2 mm and 0.8 mm, for example 0.5 mm, and Sr2 chosen between 0.8 mm and 1.5 mm, for example 1 mm; - To estimate the highest probability value, for each simulated implant size li, we determine which risk category Gi we are in using the threshold values ​​of total theoretical compression Sri and Sr2, the risk category Gi being determined by calculation from the total theoretical compression of the implant li located between these threshold values, the thresholds SI and S2 being the lower and upper limits respectively of Vault of the desired target implant which has a theoretical Vault without compression Vtsci, among the number N of patients (patient eyes) in the database that have the same risk category, we calculate the number of patients P who have a difference between the theoretical Vault without compression and the Vault actually obtained between the values ​​SI - Vtsci and S2 - Vtsci, then we divide the value P by the number N of patients in the said category Gi concerned in the Patients database,which gives the highest estimated probability value P / N. - SI is a fixed value equal to or greater than 250 microns and S2 a fixed value equal to or less than 750 microns (SI > 250 microns and S2 < 750 microns), advantageously S1 = 300 microns and S2 = 600 microns and / or S1 > 300 microns and S2 < 600 microns; - the detection of point series is performed manually on the image by the user. There is therefore no automatic detection of structures by Deep Leaming, but rather the identification of points of interest by hand on the image, the rest of the process remaining unchanged. Such a provision can be useful for correcting an inaccuracy in the automated model, or for adapting to any imaging machine if no automated model has yet been specifically trained for these images; - The patient's lens is not the patient's natural lens but an artificial one. In other words, the procedure is used in the case of an "add-on" implant, that is, not placed over the patient's natural lens but on an artificial lens after cataract surgery, for example, in order to readjust the refractive result.

[0052] These are then the same implant references as phakic implants, bearing in mind that current methods are not at all adapted to this case because they take into account measurements of the eye before cataract surgery, which are not at all the same after surgery (in particular the height of the lens and the depth of the anterior chamber).

[0053] By directly using the post-operative image of the cataract (on which there is no longer a lens but a thinner artificial lens (implant)) it is possible to find the true anatomical landmarks of the structures surrounding the future implant and predict the correct size of implant.

[0054] Moreover, the acceptable vault target is no longer the same because much lower Vaults can be tolerated and Vaults will be generally higher (because artificial crystalline is thinner than natural crystalline).

[0055] Adding new components does not, in fact, disrupt the rest of the model. Note that this is impossible in a regression formula, which is fixed once it has been developed; - The process is repeated on other radial sections of the eye to obtain a 3D map of the implantation space, which will improve accuracy, particularly when the implant is not implanted in the classic axis and / or allow the surgeon to choose another orientation to obtain the desired result; - The Patient database is accessed via an internet portal.

[0056] The development of a patient database makes it possible, in a secure manner using means known in themselves, to offer global access via an internet portal, a service which does not exist to date; - We regularly update the Patient database which is used to calculate the probability collaboratively with data from surgeons worldwide or locally with data from a given surgeon.

[0057] The present invention also relates to a device implementing the method described above.

[0058] It also relates to a device for determining the size of a phakic corrective implant for a patient's eye from a raw image of a horizontal section of the anterior segment of the eye on the one hand and a previously determined optical power of the implant Po on the other hand, characterized in that it comprises means for identifying on the image the structures corresponding to the iris I, the lens L, and the interparietal portion M of the ciliary bodies C; means for calculating the angle between a line X separating the outermost points A of the iris I and a horizontal line H; means for rotating the image to make these two lines X and H coincide; and means for detecting four series of points, namely - said two points A, substantially symmetrical with respect to the lens, formed by the outermost points of the iris I on the image, - two points B, substantially symmetrical with respect to the lens, formed by the innermost points on the image of the ciliary body C, - two points D, substantially symmetrical with respect to the lens, corresponding to the connection between the ciliary body C and its intra-parietal portion M, - a series of points E located on the anterior face F of the lens L, means of calculation by means of a polynomial function from these points of at least two versions of the surface called reconstructed surfaces (si, s2,...si) on which the implant is planned to be placed, means of calculation of the geometry of a first implant II from the determined optical power Po and from the geometric characteristics of implant II present in a determined implant database called the Supplier database, geometric simulation methods for the respective positions of implant II on said reconstructed surfaces if, s2,... if, means of calculating, from the image of these positions, the value Vti of the theoretical Vaults without compression, for each reconstructed surface si, s2,...si, the theoretical or simulated Vault without compression Vtscl retained for implant II being the average of said Vti values ​​obtained for said reconstructed surfaces, and this for each anticipated implant size li presenting the same optical power Po existing in said implant database, means of calculating the total theoretical compression CTi defined as the difference between the size of the implant li and the distance between the two points A, and for each implant li and from its theoretical or simulated Vault without compression Vtsci,of its total theoretical compression CTi and a database of operated patients (hereinafter also referred to as the Patients database) for which the difference between the theoretical Vault without compression for them and the actual postoperative Vault obtained and the total theoretical compression was calculated, calculation methods arranged to calculate the probability of obtaining a satisfactory Vault between two threshold values ​​SI and S2 from the Patients database by considering the cases of patients in the database having a determined total theoretical compression CTi, allowing the size of the implant to be chosen to be that having the highest probability of being located in this range between SI and S2.

[0059] In an advantageous embodiment, the device includes calculation means arranged to divide the Patient database into three categories Gl, G2, G3 of total theoretical compression based on the extent of the differences observed between the theoretical Vault without compression and the Vault obtained after operation, namely a low-risk category has the smallest range of difference values, a high-risk category has the largest range of difference values, and a moderate-risk category is situated between the two previous categories.

[0060] Advantageously the device includes means of accessing the patient database via an internet portal.

[0061] The invention will be better understood upon reading the following description of embodiments given below by way of non-limiting examples.

[0062] The description refers to the accompanying drawings in which:

[0063] [Fig-1] is a schematic diagram illustrating the device for elaborating the size of an intraocular phakic implant (IPI) for the correction of ametropias according to an embodiment of the invention.

[0064] [Fig.2] is a block diagram detailing the steps of the manufacturing process according to a method of embodiment of the invention.

[0065] [Fig.3] schematically shows a horizontal section of a patient's eye obtained by optical coherence tomography, the following figures 4 to 8 successively showing the steps followed on this image according to an embodiment of the process of the invention.

[0066] More specifically:

[0067] [Fig.4] shows the structure detection step.

[0068] [Fig.5] shows the step of horizontalizing the image.

[0069] [Fig.6] shows that of determining the points of interest used with the mode of realization of the invention more particularly described here.

[0070] [Fig.7] shows the reconstruction step of the surface that will serve as the support for the implant.

[0071] [Fig.8] shows the step of simulating the implant on the surface and calculating the Vault theoretical without compression.

[0072] [Fig.9] is an example of an interface screen rendering showing the simulated implant of [Fig.8] supplemented by an example of a table showing the user of the development process the results allowing them to choose the implant most favorable to the patient whose eye section was used.

[0073] [Fig. 10] is a schematic cross-sectional representation of an implant model for parameterization usable with the invention.

[0074] [Fig. 11] is a top view of an embodiment of an implant usable with the invention.

[0075] [Fig. 12] is a cross-sectional view of two types of implants usable with the invention, presented in a superimposed manner.

[0076] [Fig. 13] illustrates the main steps for simulating the position of the implant on the surface and calculating the theoretical Vault without compression according to the embodiment of the invention more particularly described here.

[0077] Figure 1 shows a device 1 implementing the method for determining the size of a corrective implant 2 for the vision of a patient's eye 3 (specification sheet 4) according to an embodiment of the invention. The determination is made by a user 5 from a raw image of a horizontal section 6 of the anterior segment of the patient's eye 3 and a predetermined optical power Po of the implant. previously by the user in a manner known in itself (appearing in the patient's identification sheet 4).

[0078] This image is obtained for example by means of a high-frequency ultrasound machine 7.

[0079] The device includes means 8 (processor) for identifying on the image 9 appearing on the screen 10 of the monitor 11 (computer) for rendering, structures of the eye (iris, lens, interparietal portions of the ciliary bodies...)

[0080] It includes means 12 for calculating angle, rotation, detecting points on the image 9, and for implementing a polynomial function f(x) allowing the geometry of a first implant II to be obtained from the determined optical power Po of the patient and from the geometric characteristics of the implants in the Suppliers database 13 where the implants are listed by size and power, and are presented for example as follows:

[0081] [TABLE 1] - SUPPLIER DATABASE (example) Size Power Optical Zone Optical Vault 13.2 -9.5 6.1 465 12.6 -10.5 5.8 465 13.7 -14.5 4.9 450

[0082] Column 1 gives the supplier reference concerning the size of the implant.

[0083] Column 2 gives the optical power of the implant in diopters

[0084] The optical zone is the central round area of ​​the implant when viewed from above. It is responsible for the optical correction of the ametropia and is a lens whose surfaces can be convex, concave, planar, or toric. Outside this zone, light rays are only slightly deviated.

[0085] The optical vault is given in microns.

[0086] The functionalities of these means will be further developed below with reference to the process.

[0087] The device 1 further includes means for simulating S(y) 14 of the implant and means 15 for calculating the value Vti of the theoretical Vaults without compression as will be described more precisely with reference to the following figures.

[0088] It finally includes means 16 for calculating the total theoretical compression CTi (defined as the difference between the size of the implant li and the distance between the two points A), and

[0089] arranged calculation means 17, for each implant li and based on its theoretical or simulated Vault without compression Vtsci, its total theoretical compression Cti and a database 18 of operated patients (hereinafter also database of patient data) for which the difference between the theoretical Vault without compression concerning them and the actual postoperative Vault obtained and the total theoretical compression has been calculated, determine the highest probability value 19 20 of being located in this range between SI and S2 allowing the choice of the implant size 21 to be retained.

[0090] The patient database 18 is, for example, structured as follows:

[0091] [TABLE 2] - PATIENT DATABASE (EXAMPLE) # comp_max = CTi vault_error 67 0.66 125.0 68 1.30 894.0 69 1.30 177.0 70 0.36 -7.0 71 0.86 114.0 72 0.96 434.0 73 0.94 36.0 74 0.98 196.0 75 0.35 -223.0 76 1.04 196.0

[0092] Column 1 gives the (confidential) reference for the patient in question (actually that of one eye of said patient), column 2 gives the total theoretical compression CTi (max compression) of said patient's eye, and column 3 gives the Vault error, that is, the difference between the theoretical uncompression Vault for the patient and the Vault actually obtained or observed in the patient. We can see here that for patients 70 and 76 the results are rather good, whereas this is not the case for patients 68 and 72.

[0093] Advantageously the device implements several Supplier databases 13, 13', ...and / or several Patient databases 18, 18'... which it has access to via the internet network 22.

[0094] In general, the means used in this device include means for capturing the various information by graphic screen, calculation means such as a computer programmed accordingly through its graphic means, a modem and / or means of connection with the internet network, means for producing the images, and means for printing these images, these means being known in themselves, but arranged in a particular way to carry out the functionalities of the process according to the invention, an embodiment of which will now be described more precisely with reference to the following figures.

[0095] Fig. 2 is a block diagram describing the embodiment of the process for developing the invention more particularly envisaged.

[0096] Subsequently, reference will also be made as we go along to figures 3 to 9 which illustrate more precisely certain steps of the process.

[0097] The first step 23 of the process consists of obtaining or measuring a raw image of the horizontal section 6 of the anterior segment of the eye 3 of the patient in whom the prosthesis will be implanted.

[0098] Figure [Fig.3] schematically represents in shades of grey such a horizontal section of the eye which will serve as a background for the operations which will follow.

[0099] In parallel, the optical defect of the patient is measured in 24 by means known in themselves and the optical power Po of correction which is necessary for him is determined (step 25).

[0100] This step can advantageously be carried out at the same station and with the same equipment as that of step 23 of measurement of the raw image of the horizontal slice of the patient, and / or additional equipment known to the person skilled in the art (not shown in [Fig.1]).

[0101] From the raw image of the section, the structures corresponding to the iris I, the lens L (in mixed lines on the figures), and the intraparietal portion M (in dashed lines on the figures) of the ciliary bodies C are identified on the image (step 26), as well as the outermost points A of the iris I.

[0102] Fig. 4 illustrates on the cross-section of Fig. 3 the physical identification of these different structures and / or points.

[0103] This identification, as we have seen, can be done automatically or physically by the user using the appropriate software directly on the screen 10 of the computer 11.

[0104] The next step 27 makes it possible to determine the angle existing between a line X separating the outermost points A of the iris I and a horizontal line H (corresponding to the horizontal line of the image), and to perform a rotation to make these two lines X and H coincide.

[0105] This step is also illustrated by [Fig.5]. The angle between line 28 (X) separating points A (the outermost points of the iris I) and horizontal line 29 (H) is measured and a rotation (arrow 30) of the image of this angle (for example by a few degrees) is carried out to make lines 28 and 29 coincide.

[0106] A step 31 of detection of points of interest is then carried out comprising points A, B, D and E, the points A (substantially symmetric with respect to the lens, formed by the outermost points of the iris I on the image having already been identified in the context of the rotation.

[0107] More precisely, and with reference also to [Fig. 6], two points B are detected, substantially symmetrical with respect to the lens, formed by the innermost points on the image of the ciliary body C, - two points D, substantially symmetrical with respect to the lens, corresponding to the connection between the ciliary body C and its intra-parietal portion M, - a series of points E located on the anterior face F of the lens L.

[0108] The next step 32 (see also [Fig.7]) consists of calculating from these points and by means of a polynomial function a surface called reconstructed surface if on which the implant is planned to be placed.

[0109] We then repeat this calculation at least once (iteration 33) to construct at least a second reconstructed surface s2.

[0110] On [Fig.7] two curves corresponding to the surfaces si and s2 have thus been represented by fitting a polynomial function, for example of the 4th degree using the method of least squares, on the one hand from the points E and B (curve si), and on the other hand from the points E and a point located in the middle of the segment drawn between the points A and D (curve s2).

[0111] The next step 34 allows the determination of the geometry or size of a first implant II from the optical power Po determined in step 25 and from the geometric characteristics of implant II present in the Supplier implant database 13.

[0112] To do this (see also [Fig.8]) we geometrically simulate (step 35) the image of the position of implant II on each of the said reconstructed surfaces si, s2, etc.

[0113] On [Fig.8] we have represented the simulation 36 of the implant on the curve s2 calculated during iteration 33.

[0114] From the image of these respective positions, we calculate (step 37) the value Vti (reference 38 on [Fig.8]) of the theoretical Vault without compression for each reconstructed surface si, s2....

[0115] The theoretical or simulated uncompression Vtscl retained of implant II is the average of said Vti values ​​obtained for said reconstructed surfaces.

[0116] An example of calculating the theoretical Vault without compression is given below (TABLE 3).

[0117] [TABLE 3] - CALCULATION OF THEORETICAL VAULT WITHOUT COMPRESSION - Retrieving the base vault from the vault_base implant - Determination of the vertical position y_base of the implant base on the simulated surface - Determining the vertical position of the implant optics in the eye: y_optics = (y_base + vault_base) - Determination of the y-coordinate of the frontmost point of the lens (y_lens) - simulated vault = optical y-lens - lens y-lens

[0118] Then (step 39) we repeat the calculations of theoretical Vault without compression Vtsci for each implant size li presenting the same optical power Po existing in said implant database.

[0119] For each implant li, we then calculate (step 40) the total theoretical compression CTi defined as the difference between the size of the implant li and the distance between the two points A.

[0120] In the embodiment of the invention more particularly described here, a step 41 of determining at least three risk categories is then carried out here, which will be used for the following step 42 of probability calculation, which will be detailed below.

[0121] Step 41 consists of separating the Patient database into three so-called risk categories Gi according to the extent of the differences observed between the theoretical Vault without compression and the Vault obtained after the patient's operation, namely a low risk category G1 defined by a total theoretical compression Cti less than a first threshold Sri, has the smallest range of difference values, a high risk category G2 defined by a total theoretical compression Cti greater than a second threshold Sr2 has the widest range of difference values ​​and a moderate risk category G3 located between the two previous categories.

[0122] This dissociation will then be used, as we will see below, to estimate the highest probability value for each simulated implant size li.

[0123] Step 42 consists in calculating the probability of obtaining a satisfactory Vault between two threshold values ​​SI and S2 from the Patients database by considering the cases of patients in the database having a determined total theoretical compression CTi.

[0124] This is done for each implant li and from its theoretical or simulated Vault without compression Vtsci, its total theoretical compression CTi and the database of operated patients (Patients database 18) for which the respective differences between their theoretical Vault without compression and the postoperative Vaults actually obtained with said respective patients, as well as their total theoretical compressions, have been calculated.

[0125] An example (TABLE 4) of probability calculation is given below in pseudocode, as a non-limiting example.

[0126] [TABLE 4] - CALCULATION OF PROBABILITY - Simulated vault recovery - comp_max recovery - Determination of upper bound and lower bound of the maximum comp_max risk category - Retrieve upper_limit and lower_limit of the interval - From the patient database Calculating the percentage of lines where vault_error is within [lower_limit - simulated_vault, upper_limit - simulated_vault] among those where comp_max is between lower_limit and upper_limit

[0127] Then (final step 43) we choose the implant size with the highest probability of being in this range between these two threshold values ​​SI and S2.

[0128] In the embodiment more particularly described here, and for the determination of the highest probability value, step 41 (which is an option) of risk determination is used as follows.

[0129] To estimate the highest probability value, for each simulated implant size li, the risk category Gi is determined using the total theoretical compression threshold values ​​Sri and Sr2. The risk category Gi is determined by calculation from the total theoretical compression of the implant li located between these threshold values. The thresholds SI and S2 are the lower and upper limits, respectively, of the Vault of the desired target implant, which has a theoretical uncompression Vault Vtsci. Among the number N of patients (patient eyes) in the database that have the same risk category, the number of patients P that have a difference between the theoretical uncompression Vault and the actual Vault between the values ​​SI - Vtsci and S2 - Vtsci is calculated. Then, the value P is divided by the number N of patients in the relevant Gi category in the Patients database.which gives the highest estimated probability value P / N.

[0130] Figure 9 shows an example of screen rendering obtained with the method and device according to one embodiment of the invention.

[0131] Table 39 of [Fig.9] shows the size of the implant selected - here the size corresponding to the implant of the supplier listed 12.6 in its catalogue - (second column) for a simulated Vault (sim Vault of 334 microns), the risk category chosen being category G3 "moderate" and the probability value with only SI and S2 being fixed at 250 and 750 (3rd line).

[0132] Fig. 10 shows the modeling assumptions of the positioning of the simulated implant 40, in the form of a flattened isosceles trapezoid showing the simulation of the approximate ends 41 in dashed line on the figure, forming the buffer zones capable of absorbing part of the compression, the simulated points 42 of application of the effective (non-absorbed) compression, the (spontaneous) Vault 43 of the implant outside the eye, subjected to no compression (vertical distance between the rear face of the optic and the line of the points of application of the compression), and the distance 44 between the points of application of the compression.

[0133] Options on the user interface can allow the surgeon to better explore the results by visualizing the position and points of contact of each implant size in the eye, modifying the desired vault window according to the case (we may want to avoid low or high vaults depending on the patient's age, anatomy (iridocorneal angle...).

[0134] Similarly, it is possible to display the possible extent of postoperative vaults with their probability to better guide the surgeon's choice (sometimes there is no perfect option and the most suitable compromise for the patient must be chosen).

[0135] By using one of the curves rather than the other or both curves which model the posing surface according to the visibility of the structures behind the iris, of the type of anatomy it is possible to explore different implantation orientations (if the measurements are carried out on all radial sections of the eye).

[0136] Fig. 11 gives a top view representation of a type 45 implant, as produced by suppliers on the market and forming part of its databases.

[0137] Its diameter 46 is that of the circle 47 in which it is inscribed. It has four end tabs 48 located at the four corners of a base of the implant forming substantially a rectangle with convex sides, tabs which will cooperate with the iris and ciliary bodies of the patient's eye, and a central circular zone 49, active for dioptric correction.

[0138] As can be seen in Fig. 12 representing two implants 50 and 51 of the same diameter, in cross-section one on top of the other, each implant has a different Vault 52, 53 and a progressive (or non-progressive) thickness e or e' in its center according to the particular design of the implant Supplier / manufacturer.

[0139] We will now describe more particularly with reference to [Fig. 13], a method of implementing the calculation of the Vault without compression.

[0140] After taking dioptric measurements on the patient's eye to determine the correction to be made in optical power, and making one or more horizontal sections of the eye to be corrected, the user of the process reconstructs the support surface of the implant in section (diagram 60 corresponding to [Fig.7]) using in particular the polynomial function f(x) - curve 61.

[0141] For each curve 61 the surface actually used 62 (see diagram 63) to simulate the position is the curve formed by each value of x of the maximum between the polynomial function f(x) and the highest point of the ciliary body (when it exists in x).

[0142] It is then assumed that the implant 64 (see diagram 65) is horizontally centered with respect to the vertical central axis 66 of the lens.

[0143] Knowing the distance separating the two points xl and x2 of application of the compression, we determine the coordinates y (f(x)) of the support surface for the positions xl and x2 corresponding to each of the points of application centered horizontally by the central axis of the crystalline.

[0144] As is self-evident and as follows from the foregoing, the present invention is not limited to the embodiments described in more particular detail. On the contrary, it encompasses all variants thereof, and in particular those in which several databases of operated patients are used (after anonymization).

Claims

1. Demands Method for preparing the size of a phakic corrective implant for the vision of a patient's eye by a user, wherein a raw image of a horizontal section (6) of the anterior segment of the patient's eye (3) is obtained from said raw image on the one hand and a previously determined optical power of the implant Po (24) on the other hand, - the structures corresponding to the iris I, the lens L, and the intraparietal portion M of the ciliary bodies C are identified on the image, - the angle existing between a line X (28) separating the outermost points A of the iris I and a horizontal line H (29) is determined, - a rotation (30) is performed to make these two lines X and H coincide, - we detect (31) four series of points, namely O the said two points A, substantially symmetrical with respect to the lens, formed by the outermost points of the iris I on the image, O two points B, substantially symmetrical with respect to the lens, formed by the innermost points on the image of the ciliary body C, O two points D, substantially symmetrical with respect to the lens, corresponding to the connection between the ciliary body C and its intraparietal portion M, A series of points E are located on the anterior face F of the lens L. From these points, at least two versions of the surface, called reconstructed surfaces (s1, s2, ..., s2), on which the implant is to be placed, are calculated (32) using a polynomial function. The geometry or size of a first implant II is determined (34) from the determined optical power and the geometric characteristics of implant II present in a specific implant database, hereafter also referred to as the Supplier database (13). The respective positions of implant II on the reconstructed surfaces s1 and s2 are geometrically simulated (35). From the image of these respective positions, the theoretical uncompressed V1 value is calculated (37) for each reconstructed surface si, s2, ..., si, the theoretical or simulated uncompressed V1. compression Vtscl retained of implant II being the average of said Vti values ​​obtained for said reconstructed surfaces, - we repeat (39) the calculations of theoretical Vault without compression Vtsci for each implant size li presenting the same optical power Po existing in said implant database, - for each implant li we calculate (40) the total theoretical compression CTi defined as the difference between the size of the implant li and the distance between the two points A, - for each implant li and from its theoretical or simulated Vault without compression Vtsci, its total theoretical compression Cti and a database of operated patients (18, 18',...(hereinafter referred to as the Patient database) for which the difference between the theoretical Vault without compression concerning them and the actual postoperative Vault obtained and the total theoretical compression concerning them has been calculated, we calculate (42) the probability of obtaining a satisfactory Vault between two threshold values ​​SI and S2 and we choose (43) the implant size presenting the highest value of probability of being in this range between SI and S2.

2. Method according to claim 1, characterized in that the Patient database is separated (41) into three risk categories Gi based on the extent of the differences observed between the theoretical Vault without compression and the Vault obtained after the patient's operation, namely a low risk category G1 defined by a total theoretical compression Cti less than a first threshold Sri, has the smallest range of difference values, a high risk category G2 defined by a total theoretical compression Cti greater than a second threshold Sr2 has the widest range of difference values ​​and a moderate risk category G3 situated between the two previous categories.

3. A method according to claim 2, characterized in that, to estimate the highest probability value, for each simulated implant size li, the risk category Gi is determined using the threshold values ​​of total theoretical compression Sri and Sr2, the risk category Gi being determined by calculation from the total theoretical compression of the implant li located between these threshold values, the thresholds SI and S2 being the lower and upper limits respectively of Vault, the desired target implant whose simulated Vault without compression is Vtsci, among the number N of patients (of eyes of patients) from the database which presents the same risk category, we calculate the number of patients P which have a difference between the theoretical Vault without compression and the Vault actually obtained between the values ​​SI -Vtsci and S2 - Vtsci, then we divide the value P by the number N of patients of said category Gi concerned in the Patients database, which gives the highest value of estimated probability P / N.

4. A method according to any one of the preceding claims, characterized in that SI is a fixed value > 250 microns and S2 is a fixed value < 750 microns, advantageously SI > 300 microns and S2 < 600 microns.

5. A method according to any one of the preceding claims, characterized in that the detection of the series of points is carried out manually on the image (9) by the user (5).

6. A method according to any one of the preceding claims, characterized in that the method is used for calculating an “add-on” implant on an artificial lens.

7. A method according to any one of the preceding claims, characterized in that the polynomial function is a 4th degree polynomial f(x) whose coefficients vary from one image to another and are adjusted by the least squares method.

8. A method according to any one of the preceding claims, characterized in that the method is repeated on other radial sections of the eye to obtain a 3D map of the implantation space.

9. A method according to any one of the preceding claims, characterized in that one or more Patient databases (18, 18',...) are accessed via an internet portal (22).

10. Device for elaborating the size of a phakic corrective vision implant of the eye (3) of a patient from a raw image (9) of a horizontal section (6) of the anterior segment of the eye on the one hand and an optical power of the implant Po previously determined on the other hand, characterized in that it comprises - means (8) for identifying on the image (9) the structures corresponding to the iris I, the lens L, and the interparietal portion M of the ciliary bodies C, - means (12) for calculating the angle existing between a line X separating the outermost points A of the iris I and a horizontal line H, - means of rotation to make these two lines X and H coincide, - means (12) for detecting four series of points, namely O the said two points A substantially symmetrical with respect to the lens, formed by the outermost points of the iris I on the image, O two points B, substantially symmetrical with respect to the lens, formed by the innermost points on the image of the ciliary body C, O two points D, substantially symmetrical with respect to the lens, corresponding to the connection between the ciliary body C and its intraparietal portion M, O a series of points E located on the anterior face F of the lens L, - means (12) for calculating, by means of a polynomial function from these points, at least two versions of the surface called reconstructed surfaces (si, s2,...si) on which the implant is planned to be placed, - means (12) for calculating the geometry of a first implant II from the determined optical power Po and from the geometric characteristics of implant II present in a determined implant database called the Supplier database (13, 13'...), - means (14) for geometric simulation of the respective positions of implant II of the implant on said reconstructed surfaces if, s2,... if, - means (15) for calculating, from the image of these positions, the value Vti of the theoretical Vaults without compression, for each reconstructed surface si, s2,... si, the theoretical or simulated Vault without compression Vtscl retained for implant II being the average of said Vti values ​​obtained for said reconstructed surfaces, and this for each anticipated implant size li presenting the same optical power Po existing in said implant database, - means (16) for calculating the total theoretical compression CTi defined as the difference between the size of the implant li and the distance between the two points A, and for each implant li and from its theoretical or simulated Vault without compression Vtsci, its total theoretical compression Cti and a database of operated patients (hereafter also Patient database) for which the difference between the theoretical Vault without compression concerning them and the actual postoperative Vault obtained and the total theoretical compression have been calculated, means (17) of calculation arranged to calculate the probability of obtaining a satisfactory Vault between two threshold values ​​SI and S2 from the Patient database by considering the cases of patients in the database having a determined total theoretical compression CTi, allowing the size of the implant (21) to be retained to be chosen as the one having the highest value (19) of probability (20) of being located in this range between SI and S2.

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