JP2020049128A - Intraocular lens selection device and intraocular lens selection program - Google Patents

Abstract

To provide an intraocular lens selection device and an intraocular lens selection program capable of selecting an appropriate intraocular lens.SOLUTION: The intraocular lens selection device for selecting an intraocular lens comprises: acquisition means for acquiring an eye shape parameter of an eye to be examined; and control means which uses an IOL offset based on the relationship between the intraocular lens diopter and the intraocular lens shape and the eye shape parameter to calculate a post-operative predictive refractive power.SELECTED DRAWING: Figure 6

Description

  The present disclosure relates to an intraocular lens selection device for selecting a power of an intraocular lens, and an intraocular lens selection program.

  2. Description of the Related Art In cataract surgery, an intraocular lens power determination device that determines the power (hereinafter, power) of an intraocular lens (hereinafter, IOL) inserted into the eye of a subject's eye after removing a lens nucleus is known (Patent Document 1). 1). In such an apparatus, the postoperative predicted anterior chamber depth (the position of the intraocular lens) is estimated to determine the intraocular lens power, and the power of the intraocular lens is calculated.

JP 2013-94410 A

  However, in the conventional intraocular lens calculation formula, it has not been possible to consider a change in shape according to the power of the intraocular lens.

  An object of the present disclosure is to provide an intraocular lens selection device and an intraocular lens selection program that can select an appropriate intraocular lens in view of the conventional problems.

  In order to solve the above problem, the present disclosure is characterized by including the following configuration.

(1) An intraocular lens selection device for selecting an intraocular lens, comprising: an acquisition unit for acquiring an eye shape parameter of an eye to be inspected; and a control unit, wherein the control unit includes an intraocular lens power and The method is characterized in that a predicted postoperative refractive power is calculated using an IOL offset based on a relationship with an intraocular lens shape and the eye shape parameter.
(2) An intraocular lens selection program executed by an intraocular lens selection device for selecting an intraocular lens, wherein the eye shape parameter of the eye to be inspected is executed by a processor of the intraocular lens selection device. Calculating an IOL offset based on the relationship between the intraocular lens power and the intraocular lens shape, and the eye shape parameter, and calculating a postoperative predicted refractive power using the intraocular lens. It is characterized by being executed by a lens selecting device.

It is a schematic structure figure explaining the composition of the ophthalmologic photographing device concerning this example. It is a figure showing the anterior segment observation screen on which the imaged anterior segment image was displayed. It is a figure showing an example of an anterior segment cross section image. It is a figure for explaining calculation of an IOL frequency. FIG. 4 is a diagram illustrating a method for calculating an offset. It is a figure explaining calculation of postoperative residual refractive power using paraxial ray tracing. It is a figure showing the shape of an intraocular lens. It is a figure showing the relation between the power of an intraocular lens and IOL offset.

<Embodiment>
Hereinafter, embodiments according to the present disclosure will be described. The intraocular lens selection device (for example, the ophthalmologic photographing device 1) of the present embodiment is a device for determining the power of the intraocular lens to be inserted into the eye to be examined. The intraocular lens selection device includes, for example, an acquisition unit (for example, the OCT optical system 100 or the control unit 80) and a control unit (for example, the control unit 80). The acquisition unit acquires eye shape parameters of the eye to be examined. The control unit calculates the postoperative predicted refractive power using the IOL offset based on the relationship between the intraocular lens power and the intraocular lens shape, and the eye shape parameter. Thus, the intraocular lens selection device can select an intraocular lens that is more suitable for the patient even if the shape of the intraocular lens changes for each power.

  The control unit may correct a change in the positional relationship between the support unit of the intraocular lens and the principal point position with respect to the intraocular lens power using the IOL offset. Thus, even if the positional relationship between the support portion and the principal point position changes for each power, an intraocular lens suitable for the patient can be selected.

  The control unit may calculate the IOL offset by inputting the intraocular lens power into the relational expression between the intraocular lens power and the IOL offset. The relational expression may be, for example, an approximate expression based on the data of the intraocular lens power and the IOL offset. As a result, even when the design data of the intraocular lens cannot be obtained, the IOL offset suitable for the intraocular lens power can be set.

  The eye shape parameter may be an ocular axial length, a predicted postoperative anterior chamber depth, an anterior corneal curvature radius, a corneal posterior curvature radius, or a corneal center thickness. The posterior corneal curvature radius may be an actually measured value or an estimated value.

  The intraocular lens selection device may select the intraocular lens from the calculation result of the intraocular lens power, or may support the selection of the intraocular lens by presenting options.

  The control unit may execute an intraocular lens selection program stored in the storage unit. The intraocular lens selection program includes, for example, an acquisition step and a calculation step. The obtaining step is, for example, a step of obtaining eye shape parameters of the eye to be inspected. The calculating step is a step of calculating a predicted postoperative refractive power using an IOL offset based on a relationship between the intraocular lens power and the intraocular lens shape, and an eye shape parameter.

<Example>
Hereinafter, embodiments according to the present disclosure will be described with reference to the drawings. The optical system of the ophthalmologic photographing apparatus 1 according to the present embodiment is built in a casing (not shown). The housing is moved three-dimensionally with respect to the eye E by driving a well-known alignment moving mechanism. In the following description, the direction of the optical axis of the subject's eye E will be described as the Z direction, the horizontal direction as the X direction, and the vertical direction as the Y direction. The surface direction of the fundus may be considered as the XY direction.

  The ophthalmologic photographing apparatus 1 includes, for example, an interference optical system (OCT optical system) and a corneal measurement optical system.

  An interference optical system (OCT optical system) 100 is provided. It is used as an imaging device for capturing a cross-sectional image of the eye E. It may be used to measure the axial length of the eye E. The OCT optical system 100 irradiates the eye E with measurement light. The OCT optical system 100 detects an interference state between the measurement light reflected from the anterior segment (for example, the cornea, the crystalline lens, etc.) and the reference light by the light receiving element (detector 120). The OCT optical system 100 includes an irradiation position changing unit (for example, an optical scanner 108) that changes the irradiation position of the measurement light on the anterior eye to change the imaging position on the anterior eye. The control unit 80 controls the operation of the irradiation position changing unit based on the set imaging position information, and acquires a tomographic image based on a light receiving signal from the detector 120.

  The OCT optical system 100 has a so-called optical coherence tomography (OCT) apparatus configuration. The OCT optical system 100 divides the light emitted from the light source 102 into measurement light (sample light) and reference light by a coupler (light splitter) 104. Then, the OCT optical system 100 guides the measurement light to the anterior ocular segment by the measurement optical system 106, and guides the reference light to the reference optical system 110. Thereafter, the detector (light receiving element) 120 receives the interference light resulting from the synthesis of the measurement light reflected by the anterior segment and the reference light.

  Light emitted from the light source 102 is split by the coupler 104 into a measurement light beam and a reference light beam. Then, the measurement light beam is emitted into the air after passing through the optical fiber. The light flux is condensed on the anterior segment via the optical scanner 108 and other optical members of the measurement optical system 106. The light reflected by the anterior segment is returned to the optical fiber via a similar optical path.

  The optical scanner 108 scans the measurement light on the eye E in the XY directions (transverse direction). The optical scanner 108 is, for example, two galvanometer mirrors, and the reflection angle thereof is arbitrarily adjusted by the drive mechanism 109.

  As a result, the light beam emitted from the light source 102 changes its reflection (progression) direction, and is scanned on the eye E in an arbitrary direction. Thereby, the imaging position on the anterior segment is changed. The optical scanner 108 may have any configuration as long as it deflects light. For example, in addition to a reflection mirror (galvano mirror, polygon mirror, resonant scanner), an acousto-optic device (AOM) for changing the traveling (deflection) direction of light is used.

  The reference optical system 110 generates reference light that is combined with reflected light obtained by the reflection of the measurement light from the eye E. The reference optical system 110 may be a Michelson type or a Mach-Zehnder type. The reference optical system 110 is formed by, for example, a reflection optical system (for example, a reference mirror), and returns the light from the coupler 104 to the coupler 104 again by reflecting the light from the reflection optical system, and guides the light to the detector 120. As another example, the reference optical system 110 is formed by a transmission optical system (for example, an optical fiber), and guides the light from the coupler 104 to the detector 120 by transmitting the light without returning.

  The reference optical system 110 has a configuration that changes an optical path length difference between the measurement light and the reference light by moving an optical member in the reference light path. For example, the reference mirror is moved in the optical axis direction. The configuration for changing the optical path length difference may be arranged in the measurement optical path of the measurement optical system 106.

  The detector 120 detects an interference state between the measurement light and the reference light. In the case of Fourier domain OCT, the spectrum intensity of the interference light is detected by the detector 120, and a depth profile (A-scan signal) in a predetermined range is obtained by Fourier transform of the spectrum intensity data. Here, the control unit 80 can acquire a tomographic image by scanning the measurement light on the anterior segment in a predetermined transverse direction by the optical scanner 108. That is, an anterior segment tomographic image of the subject's eye is captured. For example, by scanning in the X direction or the Y direction, a tomographic image (anterior tomographic image) on the XZ plane or the YZ plane of the anterior eye of the subject's eye can be acquired (in the present embodiment, measurement is performed in this manner). A method in which light is one-dimensionally scanned with respect to the anterior eye part to obtain a tomographic image is referred to as a B scan). The acquired anterior ocular segment tomographic image is stored in the memory 85 connected to the control unit 80. Furthermore, it is also possible to acquire a three-dimensional image of the anterior segment of the eye by scanning the measurement light two-dimensionally in the XY directions.

  For example, the Fourier domain OCT includes Spectral-domain OCT (SD-OCT) and Swept-source OCT (SS-OCT). Further, it may be Time-domain OCT (TD-OCT).

  In the case of the SD-OCT, a low coherent light source (broadband light source) is used as the light source 102, and the detector 120 is provided with a spectral optical system (spectrum meter) that splits the interference light into each frequency component (each wavelength component). . The spectrum meter includes, for example, a diffraction grating and a line sensor.

  In the case of SS-OCT, a wavelength scanning type light source (variable wavelength light source) that changes the emission wavelength at high speed over time is used as the light source 102, and a single light receiving element is provided as the detector 120, for example. The light source 102 includes, for example, a light source, a fiber ring resonator, and a wavelength selection filter. Examples of the wavelength selection filter include a combination of a diffraction grating and a polygon mirror, and a filter using a Fabry-Perot etalon.

  The corneal measurement optical system 300 is used for measuring a corneal shape. The corneal measurement optical system 300 is roughly divided into a projection optical system 50, an alignment optical system 40, and an anterior ocular segment imaging optical system 30.

  The projection optical system 50 has a ring-shaped light source 51 arranged around the optical axis L1 and is used to project a ring index on the cornea to measure a corneal shape (curvature, astigmatic axis angle, etc.). . Note that, for the light source 51, for example, an LED that emits infrared light or visible light is used. In the projection optical system 50, it is sufficient that at least three or more point light sources are arranged on the same circumference around the optical axis L1, and an intermittent ring light source may be used. Further, a placid target projection optical system that projects a plurality of ring targets may be used.

  The alignment optical system 40 is disposed inside the light source 51, has a light source 41 (for example, λ = 970 nm) that emits infrared light, and is used to project an alignment index on the cornea Ec. The alignment index projected on the cornea Ec is used for alignment with the eye to be inspected (for example, automatic alignment, alignment detection, manual alignment, and the like). In the present embodiment, the projection optical system 50 is an optical system that projects a ring index onto the cornea Ec, and the ring index also serves as a Meyer ring. The light source 41 of the projection optical system 40 also serves as an anterior segment illumination for illuminating the anterior segment with infrared light from an oblique direction. The projection optical system 40 may be further provided with an optical system that projects parallel light onto the cornea Ec, and the front and rear alignment may be performed in combination with finite light from the projection optical system 40.

  The anterior segment imaging optical system 30 is used to capture (acquire) an anterior segment front image. The anterior ocular segment imaging optical system 30 includes a dichroic mirror 33, an objective lens 47, a dichroic mirror 62, a filter 34, an imaging lens 37, and a two-dimensional image sensor 35. Used. The two-dimensional imaging device 35 is disposed at a position substantially conjugate with the anterior segment of the eye to be examined.

  The anterior segment reflected light from the above-described projection optical system 40 and projection optical system 50 is imaged on a two-dimensional image sensor 35 via a dichroic mirror 33, an objective lens 47, a dichroic mirror 62, a filter 34, and an imaging lens 37. You.

  The light source 10 is a fixation lamp. Further, for example, part of the anterior segment reflected light obtained by reflection of light emitted from the light source 10 at the anterior segment is reflected by the dichroic mirror 33 and imaged by the anterior segment imaging optical system 30. You.

  Next, the control system will be described. The control unit 80 controls the entire apparatus and calculates a measurement result. The control unit 80 is connected to each member of the OCT optical system 100, each member of the cornea measurement optical system 300, the display unit 70, the operation unit 84, the memory 85, and the like. A general-purpose interface such as a mouse may be used as the operation input unit, or a touch panel may be used as the operation unit 84. The memory 85 stores, in addition to various control programs, an analysis program for the control unit 80 to perform an anterior ocular segment image analysis.

<Control operation>
A control operation for determining the intraocular lens power in the apparatus having the above configuration will be described. The examiner moves the apparatus up, down, left, right and front and rear directions using an operation unit such as a joystick (not shown) while watching the alignment state of the eye to be inspected displayed on the display unit 70, and moves the apparatus to the eye to be inspected E. Put in a predetermined positional relationship. In this case, the examiner causes the subject's eye to fixate the fixation target.

  At the time of alignment, the light sources 41 and 51 are turned on. Here, the examiner performs vertical and horizontal alignment such that the reticle LC electronically displayed on the display unit 70 and the ring indexes Q1 and Q2 by the light source 41 are concentric as shown in FIG. Thereby, alignment is performed in the XY directions so that the optical axis L1 of the present apparatus passes through the cornea vertex of the eye to be examined. In addition, the examiner performs front and rear alignment so that the ring index Q1 is in focus.

  When the alignment with respect to the anterior segment is completed, the control unit 80 photographs the anterior segment of the subject's eye with the anterior segment imaging optical system 30. Further, the control unit 80 captures a cross-sectional image 500 of the eye to be inspected by the OCT optical system 100 based on a preset scanning pattern (see FIG. 3). The acquired anterior ocular segment image and cross-sectional image are stored in the memory 85 or the like.

  The control unit 80 calculates the corneal shape of the subject's eye based on the ring index images Q1 and Q2 in the anterior eye image 400 stored in the memory 85. The corneal shape is, for example, a corneal curvature radius of the anterior cornea in a strong principal meridian direction and a weak principal meridian direction, an astigmatic axis angle of the cornea, and the like. For example, the control unit 80 calculates the corneal shape based on the size and shape of the ring index images Q1, Q2.

  In addition, the control unit 80 analyzes a cross-sectional image captured using the OCT optical system 100. For example, the control unit 80 detects the position of the cornea, the lens, and the like by detecting the edge of the cross-sectional image, and measures the corneal thickness, the anterior chamber depth, and the lens thickness based on the position. Further, the control unit 80 approximates the detected anterior or posterior surface of the cornea and the lens with a circle (or ellipse approximation, conic curve approximation, etc.), and based on the approximate curve, the radius of curvature of the posterior surface of the cornea, the curvature of the anterior lens, the posterior surface of the lens. Measure the curvature and the like.

  When the measurement and the image analysis are completed, the control unit 80 calculates the intraocular lens power by partially using the known SRK / T equation, the Binkhorst equation, and the like. For example, the above measurement data is substituted into the SRK / T formula, the Binkhorst formula, and the like. When the SRK / T equation (Equation (1) below) is used, the intraocular lens power is calculated using the corneal curvature radius, the axial length, the postoperative predicted anterior chamber depth (details will be described later), and the like.

ここで、R:角膜曲率半径[mm](R＝(nk−1.000)×1000/K)、nk:検者によって選択された屈折率、LO:AL＋RT[mm]、RT:網膜の厚み[mm](RT＝0.65696−0.02029×AL)、AL:眼軸長[mm]、AD´:術後予測前房深度の補正値[mm](AD´＝H＋OF,OF＝AD−3.336)、AD:術後予測前房深度[mm](AD＝0.62467×A−68.747)、A:A定数、H:角膜高さ[mm](H=R−(R×R−((Cw×Cw)/4))1/2)（ただし、(R×R−((Cw×Cw)/4))＜0の場合、H＝R）、Cw:角膜幅[mm]、Cw＝−5.41＋0.58412×LC＋0.098×K、LC:眼軸長の補正値[mm]（AL≦24.2の場合LC＝AL、AL＞24.2の場合LC＝−3.446＋1.716×AL−0.0237×AL2）、DR:術後希望する矯正用レンズの屈折力[D]、LP:移植するIOLの度数[D]、V:頂点距離、na:房水および硝子体の屈折率(＝1.336)、nc:角膜の屈折率(＝1.333)、ncml: nc−1(＝0.333)である。

Here, R: corneal curvature radius [mm] (R = (nk-1.000) × 1000 / K), nk: refractive index selected by the examiner, LO: AL + RT [mm], RT: retinal thickness [mm] ] (RT = 0.65696-0.02029 x AL), AL: axial length [mm], AD ': corrected value of postoperative predicted anterior chamber depth [mm] (AD' = H + OF, OF = AD-3.336), AD: Predicted postoperative anterior chamber depth [mm] (AD = 0.62467 x A-68.747), A: A constant, H: corneal height [mm] (H = R-(R x R-((Cw x Cw) / 4 )) 1/2) (However, when (R × R − ((Cw × Cw) / 4)) <0, H = R), Cw: corneal width [mm], Cw = −5.41 + 0.58412 × LC + 0.098 × K, LC: correction value of the axial length [mm] (LC = AL when AL ≦ 24.2, LC = −3.446 + 1.716 × AL−0.0237 × AL2 when AL> 24.2), DR: surgery Later desired refractive power of corrective lens [D], LP: power of implanted IOL [D], V: vertex distance, na: refractive index of aqueous humor and vitreous (= 1.336), nc: refractive index of cornea (= 1.333), ncml: nc−1 (= 0.333).

ここで、補正量Ｘは、水晶体前面の位置から赤道位置（水晶体の最大径部分）ＥＰＰまでの距離である。本実施例において、赤道位置は、水晶体前面と水晶体後面とが交差する位置とされる。補正量αは、水晶体赤道位置からＩＯＬまでの距離である。補正量αは、ＩＯＬが水晶体嚢から圧力を受けることによる水晶体後嚢側または前房側への移動の影響を受ける。術後予測前房深度としては、角膜裏面から定義される場合もあるが、ここでは、角膜前面からＩＯＬまでの距離とした。 <Calculation of postoperative predicted anterior chamber depth>
Subsequently, the calculation of the postoperative predicted anterior chamber depth ELP _pred defined in the present specification will be described. The postoperative predicted anterior chamber depth ELP _pred is calculated by adding a central corneal thickness CCT, an anterior chamber depth ACD, a correction amount X, and a correction amount α with reference to the corneal vertex K, as shown in FIG. You. Therefore, the postoperative predicted anterior chamber depth ELP _pred can be expressed as in the following equation (2).

Here, the correction amount X is a distance from the position of the front surface of the crystalline lens to the equatorial position (the maximum diameter portion of the crystalline lens) EPP. In this embodiment, the equator position is a position where the front surface of the lens and the rear surface of the lens intersect. The correction amount α is a distance from the lens equator position to the IOL. The correction amount α is affected by the movement of the IOL to the posterior capsule side or the anterior chamber side due to pressure from the lens capsule. The postoperative predicted anterior chamber depth may be defined from the back of the cornea, but here, the distance from the front of the cornea to the IOL is used.

Next, a method of calculating the correction amount X will be described. 5, the distance (lens equatorial radius) h is the distance from the optical axis L ₁ to the intersection between the approximate circle of approximate circle and the lens rear surface of the lens front surface. The distance X ₁ denotes the distance from the lens front surface curvature center O ₄ in the optical axis L ₁ to the lens rear surface. The distance X ₁ ′ indicates the distance from the intersection of the approximate circle of the front surface of the lens and the approximate circle of the rear surface of the lens to the rear surface of the lens. The distance X ₂ denotes the distance from the lens rear surface curvature center O ₃ in the optical axis L ₁ to the lens front surface. Using the curvature radius R _{3 of the} front surface of the lens, the curvature radius R ₄ of the rear surface of the lens, and the thickness LT of the lens, the following equation (3) is established by Pythagorean theorem.

そして、上記の式（３）において、距離ｈが同様であるため、これらの式を補正量Ｘについて解くと以下の式（４）が成り立つ。

Then, since the distance h is the same in the above equation (3), solving these equations for the correction amount X gives the following equation (4).

Accordingly, the control unit 80 calculates the correction amount X by substituting each numerical value into the lens front curvature radius R ₃ , the lens rear surface curvature radius R ₄ , and the lens thickness LT in Expression (4). Each numerical value is obtained by analyzing a tomographic image.

<Calculation of correction amount>
Next, a method of calculating the correction amount α will be described. The control unit 80 obtains the correction amount α based on an anterior segment parameter indicating the shape of the anterior segment. The anterior ocular segment parameter is, for example, a parameter related to a crystalline lens shape. The anterior segment parameters are, for example, at least one of lens thickness, lens anterior curvature, posterior lens curvature, lens equatorial position, lens equatorial diameter, anterior chamber depth, corneal thickness, corneal diameter, and the like.

  For example, the control unit 80 calculates the correction amount α using a relational expression between the correction amount α and the anterior ocular segment parameter. This relational expression is acquired using, for example, clinical data of a patient who has inserted an intraocular lens in the past. For example, the control unit 80 obtains the measured value of the postoperative anterior chamber depth ELP by analyzing the cross-sectional image of the patient into which the intraocular lens is inserted, and obtains the measured value of the correction amount α from the measured value of the postoperative anterior chamber depth ELP. Ask for. In this case, the measured value of the correction amount α is calculated by subtracting the distance (CCT + ACD + X) from the corneal vertex K measured before the operation to the equatorial position EPP from the measured value of the postoperative anterior chamber depth ELP. Then, regression analysis is performed using the actually measured correction amount α and the anterior segment shape parameter, and a relational expression is derived from the result. In this embodiment, multiple regression analysis is used. The multiple regression analysis is, for example, an analysis method of predicting one variable with a plurality of variables. Multiple regression analysis can be performed by general statistical software or the like. By performing multiple regression analysis using a plurality of clinical data, it is possible to obtain a regression equation of the correction amount α such as the following equation (5). Equation (5) is an example of a regression equation for the correction amount α.

In the example of Equation (5), lens front surface curvature R _3, the ratio (X / LT) of the correction amount X with respect to the lens thickness, the ratio of the lens thickness for the lens diameter (lens equator diameter) (LT / DIA) is anterior segment parameters It is used as Of course, other anterior segment parameters may be used in the regression equation. Thus, a combination of a plurality of parameters may be used as an anterior segment parameter.

For example, the control unit 80 calculates the correction amount α by substituting the equation (5) for the curvature of the lens front surface R ₃ , the correction amount X, the lens thickness LT, and the lens diameter DIA. Next, the control unit 80 substitutes the correction amount X and the correction amount α calculated by the equations (4) and (5), the central corneal thickness CCT and the anterior chamber depth ACD obtained by analyzing the tomographic image into the equation (2). Thus, the postoperative predicted anterior chamber depth ELP _pred is calculated. The control unit 80 calculates the intraocular lens power by substituting the postoperative predicted anterior chamber depth ELP _pred estimated in this manner into, for example, AD ′ in Expression (1).

  The control unit 80 causes the display unit 70 to display the calculated intraocular lens power. The examiner checks the intraocular lens power displayed on the display unit 70 and selects the intraocular lens. For example, when the intraocular lens is prepared at intervals of 0.5D, the examiner selects an intraocular lens close to the displayed intraocular lens power. The examiner inputs the power of the selected intraocular lens through the operation unit 84. The control unit 80 calculates a predicted postoperative refractive power of the eye to be inspected based on the power of the selected intraocular lens. The postoperative predicted refractive power is the refractive power of the eye to be examined after the insertion of the intraocular lens.

<Calculation of predicted postoperative refractive power>
The calculation of the postoperative predicted refractive power will be described. For example, as shown in FIG. 6, the control unit 80 calculates the postoperative predicted refractive power using a paraxial ray tracing formula. First, the control unit 80 obtains the residual power P ₀ is the reciprocal of the back focus bf. The back focus bf is a distance from the front surface of the cornea to the focal point. The control unit 80 includes an IOL refractive power p ₁ , a posterior corneal refractive power p ₂ , a corneal anterior refractive power p ₃ , a distance d ₀ , a distance d ₁ , a distance d ₂ , an aqueous humor refractive index n ₀ , and an aqueous humor refractive index n _1. , The corneal refractive index n ₂ , the air refractive index n ₃ , and the corneal vertex distance VD are used to determine the back focus bf. The distance d ₀ is expressed by the following equation (6), and the distance d ₁ is expressed by the following equation (7). The distance d ₂ is the central corneal thickness (CCT).

In Equations (6) and (7), AL is the axial length, ELP _pred is the predicted postoperative anterior chamber depth, and β is the IOL offset. The IOL offset β will be described later. Control unit 80, converted by using the above parameters in the following paraxial ray tracing equation (8) tilt a ₁ ~a _3, calculate the ray height h ₁ to h _3, obtains the back focus bf.

Then the control unit calculates the residual power P ₀ is the reciprocal of the back focus bf (Equation (9)).

Residual power P ₀ corresponds to the contact lens power. The following equation (10) is used to convert this into eyeglass refractive power P.

  Usually, this equation (10) is an equation representing the postoperative residual refractive power (postoperative predicted refractive power). The postoperative residual refractive power P corresponds to the spectacle power.

<IOL offset>
The IOL offset β is a numerical value for correcting the positional relationship between the support portion and the principal point position, which changes for each power of the intraocular lens. For example, as shown in FIG. 7, the distance W from the tip of the support portion Sp of the intraocular lens to the principal point position H (or principal point position H ') differs depending on the power even for the same type of intraocular lens. There are cases. Therefore, the control unit 80 corrects the calculated position of the intraocular lens using the IOL offset β when calculating the postoperative residual refractive power.

  FIG. 8 is a graph in which the IOL offset β is plotted for each intraocular lens power such that the postoperative residual refractive power P obtained by calculation becomes equal to the actual postoperative refractive power of the patient. As shown in FIG. 8, there is a correlation between the intraocular lens power and the IOL offset β. Therefore, control unit 80 determines IOL offset β using this correlation. For example, the control unit 80 converts the relationship between the intraocular lens power and the IOL offset β into a function by regression analysis of clinical data as shown in FIG. 8 and inputs the selected intraocular lens power into the obtained relational expression. , IOL offset β.

  After calculating the IOL offset β, the control unit 80 calculates the post-operative residual refractive power according to the equations (6) to (10), and displays it on the display unit 70. The examiner determines whether the selected intraocular lens is appropriate by confirming the displayed predicted postoperative refractive power. For example, the examiner selects an intraocular lens having a postoperative residual refractive power on the minus (myopic) side so as not to overcorrect.

  As described above, the intraocular lens selection device according to the present embodiment uses the IOL offset, so that even if the positional relationship between the support portion and the principal point position changes for each power of the intraocular lens, Accurate post-operative residual refractive power can be calculated. This allows the examiner to select an intraocular lens that is more suitable for the patient.

  In the above embodiment, the control unit 80 obtains the IOL offset by regression analysis of clinical data, but is not limited to this. The control unit 80 may calculate the IOL offset based on the design data of the intraocular lens. For example, the control unit may calculate the IOL offset based on the distance from the support of the intraocular lens to the principal point position, the intraocular lens center thickness, and the intraocular lens refractive index.

  In the above embodiment, the equator position is the position where the front surface of the lens and the rear surface of the lens intersect. However, the equator position may be estimated by another calculation method.

  In this embodiment, the optical coherence tomography device for capturing an anterior ocular segment tomographic image (cross-sectional image) is used to acquire a three-dimensional shape image by acquiring an anterior ocular segment tomographic image at a plurality of scanning positions. Is also applicable. For example, the OCT optical system 100 is an anterior segment imaging device that acquires a three-dimensional cross-sectional image (three-dimensional anterior segment data) of the anterior segment, and the control unit 80 is acquired by the anterior segment imaging device. The offset distance from the front surface of the crystalline lens to the contact point between the chin zonule and the crystalline lens may be determined three-dimensionally based on the three-dimensional sectional image. In this case, the ELP may be calculated based on the average of the anterior lens curvature and the posterior lens curvature for each meridian direction in the three-dimensional anterior segment data.

  In the present embodiment, an optical coherence tomography device for capturing an anterior ocular segment tomographic image (cross-sectional image) has been described as an example of an anterior ocular segment imaging device that captures an anterior ocular segment cross-sectional image, but is not limited thereto. A projection optical system that projects light emitted from the light source toward the anterior segment of the subject's eye to form a light-section plane on the anterior segment, and before the light-section plane is acquired by scattering at the anterior segment. A light-receiving optical system having a detector that receives light including scattered light from the eye, and a configuration that forms an anterior ocular segment image based on a detection signal from the detector. That is, the present invention is also applicable to a device that projects slit light onto the anterior segment of the optometry and obtains an anterior segment cross-sectional image using a Scheimpflug camera.

  Furthermore, the present invention can be applied to an apparatus that acquires a three-dimensional shape image of the anterior segment by rotating the Scheimpflug camera or moving the camera in the horizontal or vertical direction. In this case, by performing the displacement correction for each predetermined rotation angle, it is possible to accurately acquire the three-dimensional shape image of the anterior ocular segment, and the accuracy of the measurement value acquired from the three-dimensional shape image is improved. In this case, a displacement in a direction perpendicular to the imaging surface (slit cross section) is detected, and a displacement correction process is performed based on the detection result.

  Further, in the above configuration, the anterior ocular segment cross-sectional image is obtained optically, but is not limited thereto. For example, any configuration may be used as long as a cross-sectional image of the anterior ocular segment is acquired by detecting reflection information from the anterior ocular segment using an ultrasonic probe for B scanning.

  In this embodiment, the corneal curvature radius at the front surface of the cornea is calculated using the corneal measurement optical system 300, and the corneal curvature radius at the posterior surface of the cornea is calculated using the OCT optical system 100. It is not limited to. The OCT optical system 100 may calculate the corneal curvature radius in the anterior-posterior surface of the cornea. Further, the corneal curvature radius of the anterior-posterior corneal surface may be treated by the same measurement value. That is, the radius of curvature of the cornea at the front surface of the cornea calculated by the cornea measurement optical system 300 may be used as the radius of curvature of the cornea at the front and rear surfaces of the cornea.

  In this embodiment, a corneal topography can be used as the corneal measurement optical system 300. In this case, when calculating the radius of curvature of the anterior corneal surface, the radius of curvature of the anterior corneal surface is calculated from the entire shape of the cornea. Therefore, when calculating the IOL frequency, the accuracy of the IOL frequency calculation is improved.

  When the OCT optical system 100 is an anterior ocular segment imaging device (for example, an ultrasonic B probe, an anterior ocular segment OCT) capable of imaging an anterior ocular segment cross-sectional image including a ciliary body, the control unit 80 The correction amount X may be obtained based on the position information of the ciliary body in the anterior segment cross-sectional image acquired by the OCT optical system 100. For example, a ciliary body (tip of the ciliary body) is detected from the acquired tomographic image of the anterior eye part (cross-sectional image of the anterior eye part), and the position of the chin zonule is predicted from the detected ciliary body position. Then, the position of the contact portion between the chin zonule and the lens may be detected from the predicted chin zonal position.

  Further, when the OCT optical system 100 is an anterior ocular segment imaging device (for example, an ultrasonic B probe, an anterior ocular segment OCT) capable of imaging an anterior ocular segment cross-sectional image including a contact portion between a chin zonule and a crystalline lens, The control unit 80 obtains a correction amount X by processing a contact portion in the anterior ocular segment cross-sectional image acquired by the OCT optical system 100. For example, when the chin zonule is photographed in the anterior ocular segment tomographic image (cross-sectional image), the position of the contact portion between the chin zonule and the crystalline lens may be detected from the acquired anterior ocular segment tomographic image. .

  Note that the present invention is not limited to the device described in the present embodiment. For example, an IOL frequency calculation program that performs the functions of the above embodiment is supplied to a system or an apparatus via a network or various storage media. Then, a computer (for example, CPU or the like) of the system or the apparatus can read and execute the program.

Reference Signs List 1 ophthalmologic photographing apparatus 30 anterior ocular segment front imaging optical system 40 alignment optical system 50 projection optical system 70 monitor 80 control unit 85 memory 84 operation unit 100 OCT optical system 300 cornea measurement optical system

Claims (7)

An intraocular lens selection device for selecting an intraocular lens,
Acquisition means for acquiring eye shape parameters of the eye to be inspected,
Control means,
An intraocular lens selecting apparatus, wherein the control means calculates a postoperative predicted refractive power using an IOL offset based on a relationship between an intraocular lens power and an intraocular lens shape, and the ocular shape parameter. .   2. The intraocular lens selection device according to claim 1, wherein the control unit corrects a change in a positional relationship between a support portion of the intraocular lens and a principal point position with respect to the intraocular lens power using the IOL offset. 3.   3. The intraocular lens according to claim 1, wherein the control unit calculates the IOL offset by inputting the intraocular lens power into a relational expression between the intraocular lens power and the IOL offset. 4. Selection device.   The intraocular lens selection device according to claim 3, wherein the relational expression is an approximate expression based on the data of the intraocular lens power and the IOL offset.   The intraocular lens selection device according to any one of claims 1 to 4, wherein the control unit calculates the postoperative predicted refractive power using a paraxial ray tracing formula.   The intraocular lens selection according to any one of claims 1 to 5, wherein the ocular shape parameters are an axial length, a postoperative predicted anterior chamber depth, an anterior corneal curvature radius, a corneal posterior curvature radius, and a corneal center thickness. apparatus. An intraocular lens selection program executed by an intraocular lens selection device for selecting an intraocular lens, wherein the program is executed by a processor of the intraocular lens selection device,
An acquisition step of acquiring eye shape parameters of the subject's eye,
Causing the intraocular lens selecting device to execute an IOL offset based on a relationship between the intraocular lens power and the intraocular lens shape, and a calculating step of calculating a postoperative predicted refractive power using the ocular shape parameter. An intraocular lens selection program characterized by:

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