CN111653364B - Method and device for calculating refractive power of intraocular lens - Google Patents
Method and device for calculating refractive power of intraocular lens Download PDFInfo
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Abstract
The application discloses a method and a device for calculating the refractive power of an intraocular lens, which are used for improving the accuracy of the calculation result of the refractive power of the intraocular lens. The method comprises the following steps: acquiring parameter information, human eye information and spectacle plane residual refractive power information of an intraocular lens; determining the distance between the cornea image side principal plane and the intraocular lens image side principal plane according to the parameter information of the intraocular lens and the human eye information; the refractive power of the intraocular lens is calculated from the parametric information of the intraocular lens, the information of the human eye, the distance between the principal plane of the cornea image side and the principal plane of the intraocular lens image side, and the information of the residual refractive power of the lens plane. By adopting the scheme provided by the application, the distance between the cornea image side principal plane and the intraocular lens image side principal plane is used for replacing the position of the effective intraocular lens after operation, so that the accuracy of the calculation result of the refractive power of the intraocular lens is improved.
Description
Technical Field
The application relates to the field of computers, in particular to a method and a device for calculating refractive power of an intraocular lens.
Background
Cataract is the first eye disease to occupy the leading cause of blindness worldwide, IOL (IntraOcular Lens) implantation is the most effective means for treating cataract patients at present, and how to accurately calculate the refractive power of the arithmetically implanted IntraOcular Lens, so that obtaining good expected effects has been the key research direction in the industry.
At present, the formula for calculating the refractive power of an intraocular lens has been developed to the fourth generation, which focuses more on the prediction of ELP (effective lense position, the distance from the vertex of the anterior surface of the cornea to the vertex of the anterior surface of the intraocular lens), which is considered to play an important role in the calculation of the refractive power of an intraocular lens. Many domestic specialists also make various researches and innovations on the calculation formula of the refractive power of the intraocular lens, contribute to the technical competitiveness in the field of China, and also provide more accurate cataract surgery treatment means for cataract patients in China. However, the existing refractive power calculation formula still has drawbacks, for example, in the existing formula, the information of the principal plane of the image side is not considered.
Therefore, how to provide a method for calculating the refractive power of an intraocular lens, so as to improve the accuracy of the result of calculating the refractive power of the intraocular lens, is a technical problem to be solved.
Disclosure of Invention
The embodiment of the application aims to provide an intraocular lens refractive power calculation method and device, which are used for improving the accuracy of an intraocular lens refractive power calculation result.
In order to solve the technical problems, the embodiment of the application adopts the following technical scheme: a method of intraocular lens power calculation comprising:
acquiring parameter information of an intraocular lens, eye information and lens plane residual refractive power;
determining the distance between the cornea image side principal plane and the intraocular lens image side principal plane after operation according to the parameter information and the human eye information of the intraocular lens;
and calculating the refractive power of the intraocular lens according to the parameter information of the intraocular lens, the human eye information, the distance between the postoperative cornea image side principal plane and the intraocular lens image side principal plane and the spectacle plane residual refractive power.
The application has the beneficial effects that: when the refractive power of the intraocular lens is calculated, the distance between the principal plane of the cornea image side and the principal plane of the intraocular lens image side is used for replacing the position of the effective intraocular lens after operation, so that the accuracy of the calculation result of the refractive power of the intraocular lens is improved.
In one embodiment, the parameter information of the intraocular lens includes:
the refractive index of the intraocular lens and the location of the principal plane of the image side of the intraocular lens;
the eye information includes:
the predicted value of the postoperative full cornea refractive power, the adjusted length of the eye axis and the principal plane position of the cornea image side.
In one embodiment, the calculating the refractive power of the intraocular lens based on the parameter information of the intraocular lens, the human eye information, the distance between the principal plane of the cornea image side and the principal plane of the intraocular lens image side, and the spectacle lens information includes:
substituting the refractive index of the intraocular lens, the adjusted length of the eye axis, the distance between the postoperative cornea image side principal plane and the intraocular lens image side principal plane into the following formula to calculate the refractive power of the intraocular lens:
wherein P is the refractive power of the artificial lens, AL real ELP for adjusted eye axis length real Distance between the principal plane of the cornea image and the principal plane of the intraocular lens image; k (K) real A predicted value of the total cornea refractive power after operation; REF is the residual power of the lens plane.
The beneficial effects of this embodiment lie in: the calculation is performed by adopting the full cornea refractive power formula, so that the full cornea refractive power is adopted to replace the simulated cornea curvature, the problem of calculation accuracy reduction caused by using the formula for simulating the cornea curvature when the radius of curvature of the cornea rear surface deviates from a normal value is solved, and the accuracy of the calculation result of the intraocular lens refractive power is improved.
In one embodiment, the adjusted eye axis length is determined by the following formula:
AL real ＝AL pre -(CCT+ΔCCT)；
wherein, AL real The length of the eye axis is adjusted; AL (AL) pre Eye axis length as measured preoperatively; CCT is the pre-operatively measured central thickness of the cornea; Δcct is the distance from the vertex of the posterior surface of the cornea to the principal plane of the corneal image space.
In one embodiment, the distance between the corneal image side principal plane and the intraocular lens image side principal plane is determined by the following formula:
ELP real ＝ELP-(CCT+ΔCCT)+ΔLT IOL ；
wherein ELP real Distance of the principal planes of the two lenses, the cornea and the intraocular lens; ELP is the distance from the anterior surface vertex of the cornea to the anterior surface vertex of the intraocular lens; deltaLT IOL Is the distance from the principal plane of the image of the intraocular lens to the apex of the anterior surface of the intraocular lens.
In one embodiment, the distance from the anterior corneal surface apex to the anterior intraocular lens surface apex is determined by the following equation:
ELP＝ACD+W×LT pre ；
wherein ELP is the distance from the anterior surface vertex of the cornea to the anterior surface vertex of the intraocular lens; ACD is anterior chamber depth; w is the ratio of the distance between the anterior surface apex of the preoperative natural lens and the anterior surface apex of the intraocular lens to the preoperative natural lens thickness; LT (LT) pre Is the natural lens thickness before operation.
In one embodiment, the ratio W of the position of the intraocular lens in the capsular bag to the lens thickness is determined by the following formula:
W＝a0+a1×Age+a2×WTW+a3×AL+a4×ACD+a5×LT；
wherein W is the ratio of the distance between the anterior surface apex of the preoperative natural lens and the anterior surface apex of the intraocular lens to the preoperative natural lens thickness; age is patient Age; WTW is the transverse diameter of the cornea; AL is the ocular length; ACD is the preoperative anterior chamber depth; LT is the preoperative natural lens thickness; a0 A1, a2, a3, a4 and a5 are regression coefficients obtained by performing multiple linear regression on preoperative and postoperative data.
In one embodiment, the post-operative full cornea refractive power prediction value is determined by the following formula:
K real ＝K pre -ΔK；
wherein K is real K for predicted postoperative full corneal power pre Δk is the change in refractive power of the cornea resulting from the surgical incision, which is the refractive power of the cornea prior to surgery.
The present application also provides an intraocular lens refractive power calculation apparatus comprising:
the acquisition module is used for acquiring parameters of the intraocular lens, eye information and the plane residual refractive power of the glasses;
the determining module is used for determining the distance between the cornea image side main plane and the intraocular lens image side main plane after operation according to the parameter information and the human eye information of the intraocular lens;
and the calculation module is used for calculating the refractive power of the intraocular lens according to the parameter information of the intraocular lens, the eye information, the distance between the postoperative cornea image side principal plane and the intraocular lens image side principal plane and the residual refractive power of the spectacle plane.
In one embodiment, the parameter information of the intraocular lens includes:
the refractive index of the intraocular lens and the location of the principal plane of the image side of the intraocular lens;
the eye information includes:
the predicted value of the postoperative full cornea refractive power, the adjusted length of the eye axis and the principal plane position of the cornea image side.
Drawings
FIG. 1 is a flow chart of a method of calculating intraocular lens refractive power according to an embodiment of the present application;
FIG. 2 is a diagram of an IOL optic system according to one embodiment of the application;
FIG. 3 is a schematic interface diagram of IOL power calculation software according to one embodiment of the application;
fig. 4 is a block diagram of an intraocular lens refractive power calculation device according to an embodiment of the present application.
Detailed Description
Various aspects and features of the present application are described herein with reference to the accompanying drawings.
It should be understood that various modifications may be made to the embodiments of the application herein. Therefore, the above description should not be taken as limiting, but merely as exemplification of the embodiments. Other modifications within the scope and spirit of the application will occur to persons of ordinary skill in the art.
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the application and, together with a general description of the application given above, and the detailed description of the embodiments given below, serve to explain the principles of the application.
These and other characteristics of the application will become apparent from the following description of a preferred form of embodiment, given as a non-limiting example, with reference to the accompanying drawings.
It is also to be understood that, although the application has been described with reference to some specific examples, a person skilled in the art will certainly be able to achieve many other equivalent forms of the application, having the characteristics as set forth in the claims and hence all coming within the field of protection defined thereby.
The above and other aspects, features and advantages of the present application will become more apparent in light of the following detailed description when taken in conjunction with the accompanying drawings.
Specific embodiments of the present application will be described hereinafter with reference to the accompanying drawings; however, it is to be understood that the disclosed embodiments are merely exemplary of the application, which can be embodied in various forms. Well-known and/or repeated functions and constructions are not described in detail to avoid obscuring the application in unnecessary or unnecessary detail. Therefore, specific structural and functional details disclosed herein are not intended to be limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present application in virtually any appropriately detailed structure.
The specification may use the word "in one embodiment," "in another embodiment," "in yet another embodiment," or "in other embodiments," which may each refer to one or more of the same or different embodiments in accordance with the application.
Fig. 1 is a flowchart of an intraocular lens refractive power calculation method according to an embodiment of the present application, the method comprising the steps of:
in step S11, parameter information of an intraocular lens, eye information, and lens plane residual refractive power are acquired;
in step S12, determining a distance between the main surface of the cornea image side and the main surface of the intraocular lens image side after operation according to the parameter information of the intraocular lens and the human eye information;
in step S13, the refractive power of the intraocular lens is calculated from the parameter information of the intraocular lens, the information of the human eye, the distance between the principal plane of the cornea image side and the principal plane of the intraocular lens image side after surgery, and the lens plane residual refractive power.
In the embodiment, parameter information of an intraocular lens, eye information and residual refractive power of a plane of glasses are obtained; wherein the parameter information of the intraocular lens includes a refractive index of the intraocular lens and a position of a principal plane of an image side of the intraocular lens, and the human eye information includes: the predicted value of the postoperative full cornea refractive power, the adjusted length of the eye axis and the principal plane position of the cornea image side.
Determining the distance between the cornea image side principal plane and the intraocular lens image side principal plane according to the parameter information of the intraocular lens and the human eye information;
FIG. 2 is a diagram of an IOL optic system: cornea is the Cornea, IOL is an intraocular lens, RPE is the retinal pigment epithelium (retinal pigment epithelium, RPE). H1' is the principal plane of the cornea image space, and the intersection point of the principal plane and the optical axis is B; h2' is the principal plane of the image side of the IOL, and the intersection with the optical axis is E. The intersection points of the anterior and posterior surfaces of the cornea and the optical axis are A, C, respectively, the intersection points of the anterior and posterior surfaces of the IOL and the optical axis are D, F, respectively, and the intersection point of the RPE and the optical axis is G. BC is ΔCCT, BE is ELP real BG is AL real 。
As can be readily seen from fig. 2, the IOL power calculation is equivalent to a two-lens imaging system, the first lens being the cornea and the second lens being the IOL. In an optical system, magnification varies with the position of an object. The conjugate planes at different positions correspond to different magnifications, but there is always a pair of conjugate planes of a homeotropic magnification β++1, which are called principal planes, and the intersection point of the principal planes and the optical axis is called principal point. The principal plane in the object side is called the object side principal plane, and the principal plane in the image side is called the image side principal plane. In this study, the IOL power calculation should be performed using the principal image plane, since the object at infinity is imaged onto the retina (i.e., parallel rays of light are imaged onto the retina through the ocular optical system). For a dual lens imaging system, the distance between the two lenses should be the distance of the principal planes of the image of the two lenses, not the distance of the anterior surface of the cornea to the anterior surface of the IOL. To obtain more accurate calculation results, the ELP formula should be modified, ELP real ＝ELP-(CCT+ΔCCT)+ΔLT IOL ，ELP real For the distance between the cornea and the principal plane of the IOL image, ΔCCT is the distance between the vertex of the posterior surface of the cornea and the principal plane of the IOL image, ΔLT IOL From the principal plane of the image of the intraocular lens to the anterior surface of the intraocular lensDistance of the vertices.
The refractive power of the intraocular lens is calculated from the parameter information of the intraocular lens, the human eye information, the distance between the principal plane of the cornea image side and the principal plane of the intraocular lens image side, and the residual refractive power information of the lens plane.
The application has the beneficial effects that: when the refractive power of the intraocular lens is calculated, the distance between the principal plane of the cornea image side and the principal plane of the intraocular lens image side is used for replacing the position of the effective intraocular lens after operation, so that the accuracy of the calculation result of the refractive power of the intraocular lens is improved.
In one embodiment, the parametric information for the intraocular lens includes:
refractive index of the intraocular lens and position of the principal plane of the image side of the intraocular lens;
the human eye information includes:
the predicted value of the postoperative full cornea refractive power, the adjusted length of the eye axis and the principal plane position of the cornea image side.
In one embodiment, calculating the refractive power of the intraocular lens based on the parametric information of the intraocular lens, the information of the human eye, the distance between the principal plane of the cornea image side and the principal plane of the intraocular lens image side, and the residual refractive power information of the lens plane, comprises:
the refractive index of the intraocular lens, the adjusted length of the eye axis, the distance between the main surface of the cornea image side and the main surface of the intraocular lens image side after operation and the residual refractive power of the lens surface are substituted into the following formula to calculate the refractive power of the intraocular lens:
wherein P is the refractive power of the artificial lens, AL real ELP for adjusted eye axis length real Distance between the principal plane of the cornea image and the principal plane of the intraocular lens image; k (K) real A predicted value of the total cornea refractive power after operation; REF is the residual power of the lens plane.
The cornea and the intraocular lens of the present application have a certain thickness,therefore, in the design of the formula, the principle of double-thick lens imaging is adopted for design, and in the application, ELP real The distance between the main plane of the cornea image side and the main plane of the intraocular lens image side is not the distance between the vertex of the front surface of the cornea and the vertex of the front surface of the intraocular lens, so that the difference of the cornea thickness and the intraocular lens thickness can cause the difference of imaging positions, and therefore, the ELP formula is directly designed by the main plane of the cornea image side and the main plane of the intraocular lens image side, so that the calculation result is more accurate.
REF is the postoperative residual refractive power of cataract, is used for representing patient's postoperative is myopia or hyperopia, and in the ideal state, patient's postoperative neither myopia nor hyperopia, at this moment, need not consider the influence of residual refractive power.
In the standard calculation formula, the length unit should be taken as the length unit, but in the present embodiment, the length unit is adjusted to be millimeter for the convenience of calculation, and thus, in the above formula, the values of the parameters are all amplified by 1000 times.
Specifically, this approach can be implemented in software, and FIG. 3 is a schematic interface diagram of the IOL power calculation software of the application. Wherein, the basic data of the patient is input at the upper left of the interface: ID inputs serial number, name inputs First Name of patient, first Name inputs last Name of patient; the upper right of the interface inputs the surgeon's data: name inputs the First Name of the surgeon and First Name inputs the last Name of the surgeon. Target Refr inputs the Target refractive power, AL inputs the ocular axis length, CCT inputs the corneal thickness, ACD inputs the anterior chamber depth, LT inputs the pre-operative natural lens thickness, K inputs the full cornea refractive power, WTW inputs the transverse cornea diameter. K is the preoperative full cornea refractive power, WTW is the cornea transverse diameter. Click calculations result in the IOL power at the target power.
The beneficial effects of this embodiment lie in: the calculation is performed by adopting the full cornea refractive power formula, so that the full cornea refractive power is adopted to replace the simulated cornea curvature, the problem of calculation accuracy reduction caused by using the formula for simulating the cornea curvature when the radius of curvature of the cornea rear surface deviates from a normal value is solved, and the accuracy of the calculation result of the intraocular lens refractive power is improved.
In one embodiment, the adjusted eye axis length is determined by the following formula:
AL real ＝AL pre -(CCT+ΔCCT)；
wherein, AL real The length of the eye axis is adjusted; AL (AL) pre Eye axis length as measured preoperatively; CCT is the pre-operatively measured central thickness of the cornea; Δcct is the distance from the vertex of the posterior surface of the cornea to the principal plane of the corneal image space.
The ocular axis length is the distance from the vertex of the anterior surface of the cornea to the retinal pigment epithelium, but since the cornea is not on the anterior surface of the cornea as the principal plane of the image side of the lens, correction of the ocular axis length is required. Specifically by formula AL real ＝AL pre - (CCT+DeltaCCT) correction, wherein AL real The length of the eye axis is adjusted; AL (AL) pre For the measured ocular axis length; CCT is the measured central thickness of the cornea.
In one embodiment, the distance between the principal corneal image side plane and the principal intraocular lens image side plane is determined by the following equation:
ELP real ＝ELP-(CCT+ΔCCT)+ΔLT IOL ；
wherein ELP real Distance of the principal planes of the two lenses, the cornea and the intraocular lens; ELP is the distance from the anterior surface vertex of the cornea to the anterior surface vertex of the intraocular lens; deltaLT IOL Is the distance from the principal plane of the image of the intraocular lens to the apex of the anterior surface of the intraocular lens.
The cornea is a negative meniscus lens. The front is air and the back is aqueous. Model eye parameters were set in this study as follows: the refractive index of air n1=1, the refractive index of aqueous humor n2=1.336, the refractive index of cornea n=1.376, the radius of curvature r1 of the anterior surface of the cornea set to 7.8mm, the radius of curvature r2 of the posterior surface set to 6.4mm, and the lens center thickness d set to 0.52mm. The ΔCCT calculated using the optical formula was-0.578 mm according to the above setting parameters. Although a specific numerical value of Δcct can be calculated by the above formula, due to Δlt IOL Is not a true value. In order to better conform the result of formula calculation to the actual refractive power after operation, the present studyIn the study, the delta CCT value (-0.578 mm) calculated according to the setting parameters is substituted into a calculation formula for preliminary operation. And (3) comparing the actual residual equivalent sphere power (subjective refraction result) of 3 months after operation with the residual equivalent sphere power calculated by a formula, and sequentially calculating delta CCT within +/-0.5 mm by taking 0.001mm as a step difference. And finally, taking the delta CCT value with the average value closest to 0 of the prediction error as a constant of the formula. According to the program loop calculation result, when delta CCT is taken to be-0.423, the average value of the prediction error is closest to 0.
That is, the ELP described above real Is expressed as ELP real ＝ELP-(CCT+ΔCCT)+ΔLT IOL When DeltaCCT takes constant-0.423 according to the program loop calculation result, the average value of the prediction error is closest to 0, and therefore, ELP real The formula of (2) can be modified to ELP real ＝ELP-(CCT-0.423)+LT IOL /2。
Wherein LT IOL Is the thickness of the intraocular lens.
In one embodiment, the distance from the anterior surface vertex of the cornea to the anterior surface vertex of the intraocular lens is determined by the following formula:
ELP＝ACD+W×LT pre ；
wherein ELP is the distance from the anterior surface vertex of the cornea to the anterior surface vertex of the intraocular lens; ACD is anterior chamber depth; w is the ratio of the distance between the anterior surface apex of the preoperative natural lens and the anterior surface apex of the intraocular lens to the preoperative natural lens thickness; LT (LT) pre Is the natural lens thickness before operation.
In one embodiment, the ratio W of the position of the intraocular lens in the capsular bag to the lens thickness is determined by the following formula:
W＝a0+a1×Age+a2×WTW+a3×AL+a4×ACD+a5×LT：
wherein W is the ratio of the distance between the anterior surface apex of the preoperative natural lens and the anterior surface apex of the intraocular lens to the preoperative natural lens thickness; age is patient Age; WTW is the transverse diameter of the cornea; AL is the ocular length; ACD is the preoperative anterior chamber depth; LT is the preoperative natural lens thickness; a0 A1, a2, a3, a4 and a5 are regression coefficients obtained by performing multiple linear regression on preoperative and postoperative data.
W is the ratio of the distance of the anterior surface apex of the preoperative natural lens to the anterior surface apex of the intraocular lens to the preoperative natural lens thickness, and may be related to some or all of the factors cornea transverse diameter WTW, the ocular axis length AL, anterior chamber depth ACD, lens thickness LT, age. Regression analysis is performed on the data measured before and after operation in the study, and finally a regression equation is obtained.
Specifically, the value of W is inversely related to WTW, i.e., the smaller the transverse cornea diameter, the greater the value of W, and the more posterior the IOL optic is positioned in the capsular bag, the greater the ELP value. The present study speculates that the IOL optic position was moved posteriorly due to the two climbs being squeezed by the equatorial capsular bag, since the total intraocular lens length used in the study was 12.5mm, greater than the capsular bag transverse diameter, and the IOL two climbs were located at points 3 and 9. The smaller the transverse diameter of the cornea, the smaller the transverse diameter of the corresponding capsular bag, the more significantly the IOL is squeezed by the equatorial capsular bag, and the more posteriorly the IOL's optic position is. The W value is positively correlated with age, i.e., the greater the age, the greater the W value, and the greater the ELP value, the more posterior the IOL optic is positioned in the capsular bag. The present study speculates that as age progresses, the capsular bag gradually relaxes, decreasing tension against IOL optic posterior movement, and increasing IOL optic posterior movement. Possibly different intraocular lenses will also vary in factors related to W (cornea transverse diameter WTW, eye axis length AL, anterior chamber depth ACD, lens thickness LT, age) due to the different parameters.
The analysis of the pearson correlation shows that the correlation intensity of the W value and each factor is Age > WTW > LT > AL > ACD from strong to weak. Multiple linear regression analysis of W and each factor using stepwise regression shows that W has the highest correlation with WTW, age, but the correlation with other factors is negligible, a0=1.518, a1=0.005, a2=0.138 obtained by multiple linear regression of preoperative post-operative data, and therefore the resulting regression equation is: w=1.518+0.005age-0.138 WTW.
In one embodiment, the post-operative full cornea refractive power prediction is determined by the following formula:
K rea1 ＝K pre -ΔK；
wherein K is real K for predicted postoperative full corneal power pre Δk is the change in refractive power of the cornea resulting from the surgical incision, which is the refractive power of the cornea prior to surgery.
After cataract surgery is performed on a patient, the cornea is flattened due to incision factors, and the total cornea refractive power becomes smaller. During some medical work, corneal curvature after cataract surgery was also found to be lower than before. The present application therefore contemplates that factors of post-operative corneal power degradation should be considered when calculating IOL power using the IOL power calculation formula. That is, the actual full cornea refractive power after the operation is corrected based on the actual measurement before the operation.
In the application, in order to simplify the formula, delta K is taken as 0.2, and the total cornea refractive power K is 3 months after operation real ＝K pre -0.2。
In the foregoing embodiments, a specific implementation of the disclosed aspects of the application by software is described, and the following, a scheme for calculating intraocular lens refractive power by a neural network is described, in particular as follows:
1. and establishing a neural network, wherein the neural network comprises a preprocessing model, a feature extraction model and a prediction model, and the preprocessing model, the feature extraction model and the prediction model are connected end to end.
2. After the neural network is established, training the neural network, wherein the specific training process is as follows:
training data: a large number of data samples are collected, for example, a large number of cataract patient characteristic parameters, such as ocular parameters of the eye axis, corneal curvature, anterior chamber depth, lens thickness, pupil size, etc., although other parameters may be included, such as patient age, sex, nationality, etc. Then vector information corresponding to the characteristic parameters is obtained through a preprocessing model, and the data size of the vector information is expanded in at least one of the following modes:
randomly translate up and down, left and right, randomly overturn according to a certain axis, randomly rotate in three dimensions and randomly amplify.
And inputting the vector subjected to data volume expansion into a feature extraction model.
The feature extraction model extracts important features in the vector to obtain a feature vector, so that the calculated amount is reduced, the feature vector is output to the prediction model, and the prediction model calculates the diopter of the intraocular lens based on the feature vector. Comparing the diopter of the intraocular lens output by the prediction model with the actual diopter of the cataract patient after operation for three months, taking the binary cross entropy of the predicted diopter output by the prediction model and the actual diopter of the cataract patient after operation for three months as a loss function, repeatedly iterating by using an optimization mode of random gradient descent through a back propagation algorithm until a preset iteration number is obtained, and when the preset iteration number is obtained, proving that the feature extraction model and the prediction model are trained, and at the moment, predicting the refractive power of the intraocular lens based on the neural network, so that a more accurate refractive power predicted value can be obtained.
3. When the refractive power of the intraocular lens is predicted through the trained neural network, various characteristic parameters measured before operation are obtained, and various characteristic parameters are input into a preprocessing model, wherein the preprocessing model is used for obtaining vector information corresponding to the characteristic parameters; after the preprocessing model obtains vector information, the vector information is automatically output to a feature extraction model, and feature extraction of the vector information is realized through the feature extraction model, so that feature vectors corresponding to feature parameters are obtained; after the feature extraction model obtains the feature vector, the feature vector is automatically input into a prediction model to predict the refractive power of the intraocular lens after operation through the prediction model, and the predicted refractive power of the intraocular lens is output from the output end of the prediction model.
In addition, the refractive power in the present application can also be calculated by optical path tracking:
the optical path tracing method is to calculate and simulate the path of light according to the detailed information such as the surface shape, thickness, refractive index, angle of incident light and the like of each component unit in the optical system, and for the intraocular lens, the optical path tracing method can calculate the path of light from the object image to the cornea front surface, cornea stroma, cornea back surface, aqueous humor, anterior and posterior surfaces of the intraocular lens and vitreous body until the retina passes, so that the value of the diopter of the intraocular lens in the optical system can be continuously adjusted until the value of the diopter of the intraocular lens when the intersection point of a plurality of light rays from the object image is converged on the retina is the calculated value. Compared with the existing calculation formula taking cornea and intraocular lens as thin lenses, in the scheme, the thickness of each component unit is considered, so that the visual optical characteristics of the intraocular lens can be simulated more truly, and the refractive power of the intraocular lens can be calculated more accurately.
Fig. 4 is a block diagram of an intraocular lens refractive power calculation device according to an embodiment of the present application, the device comprising the following modules:
an acquisition module 41 for acquiring parameters of the intraocular lens, information of the human eye, and a lens plane residual refractive power;
a determining module 42, configured to determine a distance between a main surface of the cornea image side and a main surface of the intraocular lens image side after operation according to the parameter information of the intraocular lens and the human eye information;
the calculating module 43 is configured to calculate the refractive power of the intraocular lens according to the parameter information of the intraocular lens, the eye information, the distance between the principal plane of the cornea image side and the principal plane of the intraocular lens image side after operation, and the residual refractive power of the lens plane.
In one embodiment, the parametric information for the intraocular lens includes:
the refractive index of the intraocular lens and the location of the principal plane of the image side of the intraocular lens;
the human eye information includes:
the predicted value of the postoperative full cornea refractive power, the adjusted length of the eye axis and the principal plane position of the cornea image side.
The above embodiments are only exemplary embodiments of the present application and are not intended to limit the present application, the scope of which is defined by the claims. Various modifications and equivalent arrangements of this application will occur to those skilled in the art, and are intended to be within the spirit and scope of the application.
Claims (2)
1. A method of calculating intraocular lens refractive power, comprising:
acquiring parameter information of an intraocular lens, eye information and lens plane residual refractive power;
determining the distance between the cornea image side principal plane and the intraocular lens image side principal plane after operation according to the parameter information and the human eye information of the intraocular lens;
calculating the refractive power of the intraocular lens according to the parameter information of the intraocular lens, the human eye information, the distance between the postoperative cornea image side principal plane and the intraocular lens image side principal plane and the spectacle plane residual refractive power;
the parameter information of the intraocular lens comprises:
the refractive index of the intraocular lens and the location of the principal plane of the image side of the intraocular lens;
the eye information includes:
the predicted value of the postoperative full cornea refractive power, the adjusted length of the eye axis and the position of the principal plane of the cornea image space;
the calculating the refractive power of the intraocular lens according to the parameter information of the intraocular lens, the human eye information, the distance between the cornea image side principal plane and the intraocular lens image side principal plane and the spectacle plane residual refractive power information comprises the following steps:
substituting the refractive index of the intraocular lens, the adjusted length of the eye axis, the distance between the postoperative cornea image side principal plane and the intraocular lens image side principal plane and the residual refractive power of the lens plane into the following formula to calculate the refractive power of the intraocular lens:
wherein P is the refractive power of the artificial lens, AL real ELP for adjusted eye axis length real Distance between the principal plane of the cornea image and the principal plane of the intraocular lens image; k (K) real A predicted value of the total cornea refractive power after operation; REF is the residue of the lens planeA refractive power;
the distance between the principal corneal image side plane and the principal intraocular lens image side plane is determined by the following formula:
ELP real ＝ELP-(CCT+ΔCCT)+ΔLT IOL ；
wherein ELP real Distance of the principal planes of the two lenses, the cornea and the intraocular lens; ELP is the distance from the anterior surface vertex of the cornea to the anterior surface vertex of the intraocular lens; deltaLT IOL Is the distance from the principal plane of the image side of the intraocular lens to the apex of the anterior surface of the intraocular lens; CCT is the pre-operatively measured central thickness of the cornea; Δcct is the distance from the vertex of the back surface of the cornea to the principal plane of the cornea image space;
the distance from the anterior surface vertex of the cornea to the anterior surface vertex of the intraocular lens is determined by the following formula:
ELP＝ACD+W×LT pre ；
wherein ELP is the distance from the anterior surface vertex of the cornea to the anterior surface vertex of the intraocular lens; ACD is the preoperative anterior chamber depth; w is the ratio of the distance between the anterior surface apex of the preoperative natural lens and the anterior surface apex of the intraocular lens to the preoperative natural lens thickness; LT (LT) pre Is the natural lens thickness before operation;
the ratio W of the position of the intraocular lens in the capsular bag to the lens thickness is determined by the following formula:
W＝a0+a1×Age+a2×WTW+a3×AL+a4×ACD+a5×LT pre ；
wherein W is the ratio of the distance between the anterior surface apex of the preoperative natural lens and the anterior surface apex of the intraocular lens to the preoperative natural lens thickness; age is patient Age; WTW is the transverse diameter of the cornea; AL is the ocular length; a0, a1, a2, a3, a4 and a5 are regression coefficients, and are obtained by performing multiple linear regression on preoperative and postoperative data;
the adjusted eye axis length is determined by the following formula:
AL real ＝AL pre -(CCT+ΔCCT)；
wherein, AL real The length of the eye axis is adjusted; AL (AL) pre Eye axis length as measured preoperatively;
the post-operative whole cornea refractive power predicted value is determined by the following formula:
K real ＝K pre -ΔK；
wherein K is real K for predicted postoperative full corneal power pre Δk is the change in refractive power of the cornea resulting from the surgical incision, which is the refractive power of the cornea prior to surgery.
2. An intraocular lens refractive power calculation apparatus, comprising:
the acquisition module is used for acquiring parameters of the intraocular lens, eye information and the plane residual refractive power of the glasses;
the determining module is used for determining the distance between the cornea image side main plane and the intraocular lens image side main plane after operation according to the parameter information and the human eye information of the intraocular lens;
the calculation module is used for calculating the refractive power of the intraocular lens according to the parameter information of the intraocular lens, the human eye information, the distance between the cornea image side principal plane and the intraocular lens image side principal plane after operation and the residual refractive power of the lens plane;
the parameter information of the intraocular lens comprises:
the refractive index of the intraocular lens and the location of the principal plane of the image side of the intraocular lens;
the eye information includes:
the predicted value of the postoperative full cornea refractive power, the adjusted length of the eye axis and the position of the principal plane of the cornea image space;
calculating the refractive power of the intraocular lens according to the parameter information of the intraocular lens, the human eye information, the distance between the cornea image side principal plane and the intraocular lens image side principal plane and the spectacle plane residual refractive power information, comprising:
substituting the refractive index of the intraocular lens, the adjusted length of the eye axis, the distance between the postoperative cornea image side principal plane and the intraocular lens image side principal plane and the residual refractive power of the lens plane into the following formula to calculate the refractive power of the intraocular lens:
wherein P is the refractive power of the artificial lens, AL real ELP for adjusted eye axis length real Distance between the principal plane of the cornea image and the principal plane of the intraocular lens image; k (K) real A predicted value of the total cornea refractive power after operation; REF is the residual refractive power of the lens plane;
the distance between the principal corneal image side plane and the principal intraocular lens image side plane is determined by the following formula:
ELP real ＝ELP-(CCT+ΔCCT)+ΔLT IOL ；
wherein ELP real Distance of the principal planes of the two lenses, the cornea and the intraocular lens; ELP is the distance from the anterior surface vertex of the cornea to the anterior surface vertex of the intraocular lens; deltaLT IOL Is the distance from the principal plane of the image side of the intraocular lens to the apex of the anterior surface of the intraocular lens; CCT is the pre-operatively measured central thickness of the cornea; Δcct is the distance from the vertex of the back surface of the cornea to the principal plane of the cornea image space;
the distance from the anterior surface vertex of the cornea to the anterior surface vertex of the intraocular lens is determined by the following formula:
ELP＝ACD+W×LT pre ；
wherein ELP is the distance from the anterior surface vertex of the cornea to the anterior surface vertex of the intraocular lens; ACD is the preoperative anterior chamber depth; w is the ratio of the distance between the anterior surface apex of the preoperative natural lens and the anterior surface apex of the intraocular lens to the preoperative natural lens thickness; LT (LT) pre Is the natural lens thickness before operation;
the ratio W of the position of the intraocular lens in the capsular bag to the lens thickness is determined by the following formula:
W＝a0+a1×Age+a2×WTW+a3×AL+a4×ACD+a5×LT pre ；
wherein W is the ratio of the distance between the anterior surface apex of the preoperative natural lens and the anterior surface apex of the intraocular lens to the preoperative natural lens thickness; age is patient Age; WTW is the transverse diameter of the cornea; AL is the ocular length; a0, a1, a2, a3, a4 and a5 are regression coefficients, and are obtained by performing multiple linear regression on preoperative and postoperative data;
the adjusted eye axis length is determined by the following formula:
AL real ＝AL pre -(CCT+ΔCCT)；
wherein, AL real The length of the eye axis is adjusted; AL (AL) pre Eye axis length as measured preoperatively;
the post-operative whole cornea refractive power predicted value is determined by the following formula:
K real ＝K pre -ΔK；
wherein K is real K for predicted postoperative full corneal power pre Δk is the change in refractive power of the cornea resulting from the surgical incision, which is the refractive power of the cornea prior to surgery.
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| CN112957004B (en) * | 2021-02-01 | 2023-12-19 | 复旦大学附属眼耳鼻喉科医院 | Lens curvature and diopter acquisition method and system based on IOLMaster image |
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