JP7466727B2 - Ophthalmic Equipment - Google Patents

Description

The present invention relates to an ophthalmic device for determining refractive power, which represents the refractive state of the eye.

It is known that the refractive power of the eye varies throughout the day due to various factors. Therefore, strictly speaking, the optimal power of corrective devices such as glasses and contact lenses varies depending on the time of day. For example, the optimal eyeglass power during the day is strictly different from the optimal power at night. A refractometer is generally used to measure the refractive power of the eye.

It is known that fundus tissue also varies during the day. For example, research into the daily variation in choroidal thickness is ongoing (see, for example, Non-Patent Documents 1 and 2). It is also thought that the position of the retina fluctuates with changes in choroidal thickness.

There are two methods for testing the refractive power of the eye: subjective refraction and objective refraction (see, for example, Patent Documents 1 and 2). Subjective refraction is a subjective test in which the refractive power of the test eye is determined according to the test subject's response to a visual target (such as a Landolt ring) presented to the test eye. Objective refraction is an objective test in which the refractive power of the test eye is determined based on changes in the size and shape of the image of reflected light projected onto the fundus of the test eye.

JP 2016-077774 A JP 2017-080135 A

Shinichi Usui et al., “Circadian Changes in Subfoveal Choroidal Thickness and the Relationship with Circulatory Factors in Healthy Subjects”, Investigative Ophthalmology & Visual Science, April 2012, Vol. 53, No.4, pp. 2300-2307 Colin S. Tan et al., “Diurnal Variation of Choroidal Thickness in Normal, Healthy Subjects Measured by Spectral Domain Optical Coherence Tomography”, Investigative Ophthalmology & Visual Science, January 2012, Vol. 53, No.1, pp. 261-266

In subjective refraction measurement, the visual target (visible light) presented to the subject's eye is detected by the photoreceptor cells, so the subjective refractive power can be said to roughly represent the refractive power in the range from the corneal surface to the vicinity of the photoreceptor inner-outer segment junction (IS/OS). Therefore, if the position of the IS/OS varies throughout the day, it is thought that the subjective refractive power also varies throughout the day. Optical coherence tomography (OCT) is known as a method for acquiring information along the depth direction of the fundus. By identifying the position of the IS/OS from multiple OCT images of the fundus acquired at various times, it may be possible to detect the diurnal variation of the subjective refractive power.

On the other hand, objective refraction measurement detects reflected light from the fundus, so it is believed that the contribution of reflected light from highly reflective tissues in the fundus is large. Typically, tissues from the photoreceptor outer segment (OS) to the retinal pigment epithelium (RPE) are thought to have a large effect on the measurement results.

In addition, because near-infrared light is used in objective refraction measurements, it is believed that reflections from areas deeper than the photoreceptor cells that detect visible light (such as the choroid) also contribute to the measurement results. In particular, when the choroid is thin, reflections of light that reach the sclera may affect the measurement results.

In this way, there is a difference between subjectively obtained refractive power and objectively obtained refractive power due to the difference in the measurement principles used.

In addition, to measure the diurnal variation in refractive power, measurements must be taken at least every few hours, which is not practical considering the complexity and the burden it places on the subject.

The object of the present invention is to estimate the refractive power at a time different from the time when the refractive power was measured.

An ophthalmic device according to some exemplary embodiments includes a refraction measurement unit, an OCT unit, a time recording unit, a layer position data acquisition unit, and a data processing unit. The refraction measurement unit objectively measures the refractive power of the test eye. The OCT unit acquires OCT data by applying an optical coherence tomography (OCT) scan to the fundus of the test eye. The time recording unit records the measurement time, which is the time when the OCT unit performs the OCT scan. The layer position data acquisition unit acquires layer position data including position data of the anterior surface of the choroid of the fundus and position data of the posterior surface of the choroid by analyzing the OCT data. The data processing unit calculates choroid thickness data based on the layer position data. Furthermore, the data processing unit calculates an estimate of the refractive power of the test eye at a specified time based on standard data of the diurnal variation in choroidal thickness obtained by periodic regression analysis using at least choroidal thickness as a variable, the measurement time recorded by the time recording unit, the measurement data acquired by the refraction measurement unit, and the choroidal thickness data.

According to the embodiment, it is possible to estimate the refractive power at a time different from the time when the refractive power was measured.

1 is a schematic diagram illustrating an example of a configuration of an ophthalmologic apparatus according to an exemplary embodiment. 10 is a flowchart illustrating an example of an operation of an ophthalmologic apparatus according to an exemplary embodiment. 10 is a flowchart illustrating an example of an operation of an ophthalmologic apparatus according to an exemplary embodiment. 1 is a schematic diagram illustrating an example of a configuration of an ophthalmologic apparatus according to an exemplary embodiment. 10 is a flowchart illustrating an example of an operation of an ophthalmologic apparatus according to an exemplary embodiment.

Ophthalmic devices according to some exemplary embodiments will be described in detail with reference to the drawings.

First, an overview of the embodiment will be described. The ophthalmologic apparatus of the embodiment is configured to acquire the objective refractive power of the test eye and OCT data of the fundus, analyze the OCT data to acquire position data of a specific layer of the fundus (layer position data), and generate refractive power data of the test eye based at least on the objective refractive power and the layer position data.

Obtaining the objective refractive power may be, for example, either by measurement using an objective refraction measuring device, or by receiving objective refractive power data from an electronic medical record system or the like. Similarly, obtaining the OCT data may be, for example, either by measurement using an OCT device (OCT scanning and construction of image data), or by receiving OCT data from a medical image archiving system or the like.

The ophthalmic device of the embodiment may include either one or both of an objective refraction measurement device and an OCT device. The ophthalmic device of the embodiment may also include a device (communication interface, input/output interface, etc.) that accepts data from an external device or a recording medium.

Thus, the ophthalmic device of the embodiment may be, for example, any of the following: (A) an examination device including an objective refraction measurement device (refraction measurement unit) and an OCT device (OCT unit); (B) an examination device including an objective refraction measurement device (refraction measurement unit) but not an OCT device (OCT unit); (C) an examination device including an OCT device (OCT unit) but not an objective refraction measurement device (refraction measurement unit); (D) an information processing device including neither an objective refraction measurement device (refraction measurement unit) nor an OCT device (OCT unit).

The ophthalmic device of the embodiment includes a processor programmed to analyze OCT data and generate layer position data, and a processor programmed to generate refractive power data based at least on the objective refractive power and the layer position data. These processors may be the same as each other in terms of hardware, or may be separate pieces of hardware.

In this specification, the term "processor" refers to a circuit such as a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), an ASIC (Application Specific Integrated Circuit), or a programmable logic device (e.g., an SPLD (Simple Programmable Logic Device), a CPLD (Complex Programmable Logic Device), or an FPGA (Field Programmable Gate Array)). A processor realizes a specific function by, for example, reading and executing a program stored in a memory circuit or a storage device.

The refractive power data generated by the ophthalmic apparatus of the embodiment may be any data that can be used or referred to as the refractive power of the subject's eye. For example, the refractive power data of the embodiment may be a correction value (corrected value of objective refractive power) based on measurement data of the objective refractive power. Furthermore, this correction value of the objective refractive power may be a subjective refractive power (estimated value). Alternatively, the refractive power data of the embodiment may be an objective refractive power (estimated value) at a certain time based on the objective refractive power obtained by a measurement performed at another time.

In this specification, unless otherwise specified, no distinction is made between "image data" and the "image" based on the image data. Furthermore, unless otherwise specified, no distinction is made between a part or tissue of the subject's eye and an image representing the part or tissue.

First Embodiment
<Configuration>
An example of the configuration of an ophthalmic apparatus according to an embodiment is shown in Fig. 1. The ophthalmic apparatus 1 is an apparatus of the above-mentioned type (A), that is, an examination apparatus including an objective refraction measurement apparatus (refraction measurement unit) and an OCT apparatus (OCT unit). The ophthalmic apparatus 1 includes a refraction measurement unit 10, an OCT unit 20, and a computer 30. The computer 30 includes a layer position data acquisition unit 40, a data processing unit 50, and a control unit 60.

The refraction measurement unit 10 objectively measures the refractive power of the subject's eye E. The refraction measurement unit 10 has a configuration similar to that of a known refractometer, for example. Although not shown in the figures, a typical refractometer includes a projection system, a light receiving system, and a processor, as disclosed in Patent Documents 1 and 2.

The projection system of the refraction measurement unit 10 projects light emitted from a light source onto the fundus Ef of the subject's eye E. The projection system projects light from the light source onto the fundus Ef through, for example, a collimator lens, a focusing lens, a relay lens, a pupil lens, a holed prism, a decentered prism, an objective lens, etc.

The light receiving system of the refraction measurement unit 10 projects the reflected light from the fundus Ef onto the image sensor through an objective lens, a decentered prism, a holed prism, another pupil lens, another relay lens, another focusing lens, a conical prism, an imaging lens, etc. This allows the ring pattern to be detected by the image sensor.

The processor of the refraction measurement unit 10 is programmed to process the output from the image sensor of the light receiving system to calculate the objective refraction power, and for example, executes a process to determine the deviation (position shift, deformation, etc.) of the ring pattern image acquired by the image sensor from a reference pattern, and a process to determine the objective refraction power (measurement data) from this deviation.

The OCT unit 20 applies an OCT scan to the fundus Ef to obtain OCT data. The OCT data may be interference signal data, reflection intensity profile data obtained by applying a Fourier transform to the interference signal data, or image data obtained by applying image representation to the reflection intensity profile data.

The OCT method that the OCT unit 20 can implement is typically Fourier domain OCT, but may be either spectral domain OCT or swept source OCT. Swept source OCT is a method in which light from a tunable light source is split into measurement light and reference light, the return light of the measurement light projected on the test object is superimposed on the reference light to generate interference light, the interference light is detected by a photodetector, and the detection data (interference signal data) collected in response to the wavelength sweep and the measurement light scan is subjected to Fourier transform or the like to form reflection intensity profile data. On the other hand, spectral domain OCT is a method in which light from a low coherence light source (broadband light source) is split into measurement light and reference light, the return light of the measurement light projected on the test object is superimposed on the reference light to generate interference light, the spectral distribution of the interference light is detected by a spectroscope, and the detection data (interference signal data) by the spectroscope is subjected to Fourier transform or the like to form reflection intensity profile data. In other words, swept-source OCT is an OCT method that acquires the spectral distribution in a time-division manner, and spectral-domain OCT is an OCT method that acquires the spectral distribution in a space-division manner.

The OCT unit 20 has a configuration similar to that of a known OCT device, for example. Although not shown in the figures, a typical OCT device includes a light source, an interference optical system, a scanning system, a detection system, and a processor, as disclosed in Patent Documents 1 and 2.

The light output from the light source is split into measurement light and reference light by an interference optical system. The reference light is guided by a reference arm. The measurement light is projected onto the fundus Ef through the measurement arm. A scanning system is provided in the measurement arm. The scanning system includes, for example, a galvano scanner, and is capable of deflecting the measurement light two-dimensionally.

The measurement light projected onto the fundus Ef is reflected and scattered at various depth positions (layer boundaries, etc.) of the fundus Ef. The return light of the measurement light from the test eye E is combined into reference light by an interference optical system. The return light of the measurement light and the reference light generate interference light according to the principle of superposition. This interference light is detected by a detection system. The detection system typically includes a spectrometer in spectral domain OCT and a balanced photodiode and a data acquisition system (DAQ) in swept source OCT.

The processor of the OCT unit 20 constructs OCT data (typically image data) based on detection data from the detection system. As with conventional OCT data processing, the processor applies filter processing, fast Fourier transform (FFT), and the like to the detection data to construct reflection intensity profile data for each A-line (path of measurement light within the subject's eye E). Furthermore, the processor applies imaging processing (image representation) to this reflection intensity profile data to construct image data (A-scan data) for each A-line.

The processor can construct B-scan data by arranging a plurality of A-scan data according to a scan mode of the scan system. The processor can construct stack data by arranging a plurality of B-scan data according to a scan mode of the scan system. The processor can construct volume data (voxel data) from the stack data. The processor can render the stack data or the volume data. Rendering techniques include volume rendering, multiplanar reconstruction (MPR), surface rendering, projection, etc.

The computer 30 executes various calculations and various controls for operating the ophthalmic device 1. The computer 30 includes one or more processors and one or more storage devices. Examples of storage devices include random access memory (RAM), read-only memory (ROM), hard disk drive (HDD), and solid state drive (SSD). Various computer programs are stored in the storage devices, and the calculations and controls related to this example are realized by the processor operating based on the programs. In this example, with this configuration, the processor functions as each of the layer position data acquisition unit 40, the data processing unit 50, and the control unit 60.

The layer position data acquisition unit 40 acquires layer position data of the fundus Ef by analyzing the OCT data acquired by the OCT unit 20. The layer position data includes position data of one or more layers of the fundus Ef. Each of the one or more layers corresponds to a tissue or tissue boundary of the fundus Ef. Known tissues of the fundus Ef include the internal limiting membrane, nerve fiber layer, ganglion cell layer, inner plexiform layer, inner nuclear layer, outer plexiform layer, outer nuclear layer, external limiting membrane, photoreceptor layer, retinal pigment epithelium layer, choroid, and sclera. The layer position data includes position data for a predetermined layer. This layer can be arbitrarily determined and may be, for example, IS/OS, RPE, choroid, sclera, etc.

The process of identifying layers from OCT data typically includes segmentation. Segmentation is a well-known process for identifying partial regions in image data. The layer position data acquisition unit 40 performs segmentation, for example, based on the brightness values of the OCT image data. That is, each layer tissue of the fundus Ef has a characteristic reflectance, and the image regions corresponding to these layer tissues also have characteristic brightness values. The layer position data acquisition unit 40 can identify the target image region (layer) by performing segmentation based on these characteristic brightness values.

The data processing unit 50 generates refractive power data for the subject's eye E based at least on the objective refractive power (measurement data) acquired by the refraction measurement unit 10 and the layer position data acquired by the layer position data acquisition unit 40. An example of the processing performed by the data processing unit 50 will be described later.

As described above, the refractive power data obtained by the data processing unit 50 may be any data that can be used or referenced as the refractive power of the test eye E. Specifically, this refractive power data may be any one of a corrected value of the objective refractive power (e.g., an estimated value of the subjective refractive power), an estimated value of the objective refractive power at a time different from the time when the measurement is performed by the refraction measurement unit 10, and an estimated value of the subjective refractive power at a time different from the time when the measurement is performed by the refraction measurement unit 10.

The control unit 60 controls each part of the ophthalmic device 1. The control unit 60 can control a display device (not shown). The display device functions as part of a user interface and displays information under the control of the control unit 60. The display device may be, for example, a liquid crystal display (LCD) or an organic light emitting diode (OLED) display.

The control unit 60 can control the ophthalmic apparatus 1 according to signals from an operation device (not shown). The operation device functions as part of the user interface unit. The operation device may include various hardware keys (joystick, buttons, switches, etc.) provided on the ophthalmic apparatus 1. The operation device may also include various peripheral devices (keyboard, mouse, joystick, operation panel, etc.) connected to the ophthalmic apparatus 1. The operation device may also include various software keys (buttons, icons, menus, etc.) displayed on a touch panel.

The ophthalmic device 1 may be configured to obtain refractive power data from the thickness of one or more layers of the fundus Ef. For example, the layer position data acquisition unit 40 acquires layer position data including position data of a first layer and position data of a second layer of the fundus Ef. Each of the first layer and the second layer may be a predetermined layer.

Furthermore, the data processing unit 50 obtains distance data between the first layer and the second layer based on this layer position data. This process is typically performed based on the number of pixels existing between the first layer and the second layer and a predetermined pixel-to-pixel distance. The distance measurement is performed along a predetermined direction. The distance measurement direction may be, for example, a direction determined by the OCT scan (e.g., the traveling direction of the measurement light) or a direction determined based on the OCT data (e.g., a direction perpendicular to the layer). The distance data may be distance distribution data between the first layer and the second layer, a statistical value calculated from this distance distribution data (e.g., the average, maximum value, minimum value, median, mode, variance, standard deviation), or distance data between a representative point on the first layer and a representative point on the second layer.

Next, the data processing unit 50 generates refractive power data for the subject's eye E based at least on the objective refractive power measurement data acquired by the refraction measurement unit 10 and the distance data calculated from the layer position data. In this way, the ophthalmic device 1 is capable of calculating refractive power data from the thickness of one or more layers of the fundus Ef.

The thickness of the layer of the fundus Ef referenced to obtain the refractive power data may be the choroidal thickness, which is known to vary during the day. For example, the layer position data acquisition unit 40 identifies the anterior and posterior surfaces of the choroid of the fundus Ef and generates layer position data including position data of the anterior choroid surface and position data of the posterior choroid surface.

Furthermore, the data processing unit 50 obtains distance data between the anterior choroidal surface and the posterior choroidal surface based on the position data of the anterior choroidal surface and the position data of the posterior choroidal surface. This distance data is choroidal thickness data. The choroidal thickness data may be thickness distribution data, a statistical value calculated from this thickness distribution data, or representative thickness data.

Next, the data processing unit 50 generates refractive power data for the subject eye E based at least on the objective refractive power measurement data acquired by the refraction measurement unit 10 and the choroidal thickness data. In this way, the ophthalmic device 1 is able to obtain the refractive power data from the choroidal thickness of the fundus Ef.

The ophthalmic device 1 can obtain a correction value of the objective refractive power based on the choroidal thickness of the subject's eye E. Several examples are described below. In each example, the data processing unit 50 is configured to obtain an estimate of the subjective refractive power of the subject's eye E based at least on the measurement data of the objective refractive power acquired by the refraction measurement unit 10 and the choroidal thickness data. Here, the data processing unit 50 may be configured to convert the objective refractive power to the subjective refractive power using a correction formula that has at least the choroidal thickness as a variable. This correction formula may be, for example, a linear correction formula, but may also be a nonlinear correction formula. Note that in each of the following examples, a case where an estimate of the subjective refractive power is obtained as the correction value of the objective refractive power will be particularly described, but the correction value of the objective refractive power is not limited to an estimate of the subjective refractive power, and may be a value obtained by applying any correction process to the objective refractive power (measurement data).

A first example of processing for estimating subjective refractive power based on choroidal thickness will be described. In this example, the data processing unit 50 calculates an estimate of the subjective refractive power of the subject's eye E based on a predetermined correction equation with choroidal thickness as a variable, the objective refractive power measurement data acquired by the refraction measurement unit 10, and the choroidal thickness data.

In this example, an estimate of subjective refraction is obtained by scaling (linear correction) the objective refraction using choroidal thickness (CT) as a variable. The objective refraction (OR) is, for example, spherical power (S) or spherical equivalent (SE).

The linear correction formula applicable in this example may be the following conversion formula for converting objective refraction (OR) to subjective refraction (SR): SR = OR + b(CT). Here, b(CT) is a function that determines the amount of correction, with choroidal thickness (CT) as a variable. By substituting the objective refraction measurement data (OR) acquired by the refraction measurement unit 10 and the correction amount b(CT) corresponding to the value (CT) indicated in the choroidal thickness data of the subject's eye E into the correction formula, an estimate (SR) of the subjective refraction of the subject's eye E can be obtained.

Another linear correction formula that can be applied in this example is shown below: SR = OR x c(CT). Here, c(CT) is a function that determines the correction ratio, with choroidal thickness (CT) as a variable. By substituting the objective refractive power measurement data (OR) acquired by the refraction measurement unit 10 and the correction ratio c(CT) corresponding to the value (CT) indicated in the choroidal thickness data of the test eye E into the correction formula, an estimate (SR) of the subjective refractive power of the test eye E can be obtained.

The above two examples can be combined to apply the following linear correction formula: SR = OR x c(CT) + b(CT). By substituting the objective refractive power measurement data (OR) acquired by the refraction measurement unit 10, the correction ratio c(CT) corresponding to the value (CT) indicated in the choroidal thickness data of the test eye E, and the correction amount b(CT) corresponding to the value (CT) indicated in this thickness data into the correction formula, an estimate (SR) of the subjective refractive power of the test eye E can be obtained.

Note that a correction formula similar to the correction formula in this example can also be applied to calculations other than the estimation of subjective refractive power. The same applies below.

A second example of a process for estimating subjective refractive power based on choroidal thickness will be described. If the choroidal thickness differs, the degree of influence on the refractive power conversion may differ. For example, it may not be appropriate to apply the same conversion formula (correction formula) to both an eye with a particularly thin choroid and an eye with a particularly thick choroid. From this perspective, it is possible to divide choroidal thickness values into multiple ranges, provide correction formulas corresponding to each range, and selectively apply these correction formulas.

A specific example will be described. The data processing unit 50 in this example prestores two or more correction formulas corresponding to two or more ranges of choroidal thickness values. The data processing unit 50 selects a correction formula corresponding to the choroidal thickness data of the test eye E from among these correction formulas. The selection of this correction formula includes, for example, a process of selecting a range to which the choroidal thickness value indicated in the choroidal thickness data of the test eye E belongs from two or more ranges of choroidal thickness values, and a process of identifying the correction formula corresponding to the selected range. Furthermore, the data processing unit 50 inputs the measurement data of the objective refractive power acquired by the refraction measurement unit 10 into the selected correction formula, thereby obtaining an estimate of the subjective refractive power of the test eye E.

In this example, two or more correction equations corresponding to two or more ranges of choroidal thickness values ( _CTm : m=1, 2, ..., M; M is an integer equal to or greater than 2) are prepared, for example, _SRm =OR+ _bm ( _CTm ), _SRm = _ORxcm ( _CTm ), and _SRm = _ORxcm ( _CTm )+ _bm ( _CTm ). Here, it is assumed that _SRm =OR+ _bm ( _CTm ) is stored in the data processing unit 50.

The data processing unit 50 determines which of two or more ranges _CTm the value indicated in the choroidal thickness data obtained from the OCT data acquired by the OCT unit 20 belongs to. For example, when the value indicated in the choroidal thickness data belongs to the range _CT1 , the data processing unit 50 selects a correction equation _SR1 = OR + _b1 ( _CT1 ) corresponding to the range _CT1 from among the M correction equations. Furthermore, the data processing unit 50 obtains _an estimated value ( _SR1 ) of the subjective refractive power of the test eye E by substituting the measurement data (OR) of the objective refractive power acquired by the refraction measurement unit 10 and a correction amount _b1 ( _CT1 ) corresponding to the value indicated in the choroidal thickness data of the test eye E into the selected correction equation SR1 = OR + _b1 ( _CT1 ).

A third example of a process for estimating the subjective refractive power based on the choroidal thickness will be described. The variable for linear correction is not limited to only the choroidal thickness. For example, the data processing unit 50 may be configured to obtain an estimate of the subjective refractive power of the subject's eye E based on a predetermined correction formula with the choroidal thickness and the refractive power as variables, the measurement data of the objective refractive power acquired by the refraction measurement unit 10, and the choroidal thickness data.

In this example, the subjective refractive power is estimated by scaling (linear correction) the objective refractive power using choroidal thickness (CT) and objective refractive power (OR) as variables.

The linear correction formula applicable in this example may be the following conversion formula for converting the objective refraction power (OR) to the subjective refraction power (SR): SR = OR + b(CT, OR). Here, b(CT, OR) is a function for determining the correction amount, with the choroidal thickness (CT) and the objective refraction power (OR) as variables. By substituting the objective refraction power measurement data (OR) acquired by the refraction measurement unit 10, the value (CT) indicated in the choroidal thickness data of the test eye E, and the correction amount b(CT, OR) corresponding to the measurement data (OR) into the correction formula, an estimate (SR) of the subjective refraction power of the test eye E can be obtained.

Another linear correction formula that can be applied in this example is shown below: SR = OR x c (CT, OR). Here, c (CT, OR) is a function that determines the correction ratio, with choroidal thickness (CT) and objective refraction (OR) as variables. By substituting the objective refraction measurement data (OR) acquired by the refraction measurement unit 10, the value (CT) indicated in the choroidal thickness data of the test eye E, and the correction ratio c (CT, OR) corresponding to the measurement data (OR) into the correction formula, an estimate (SR) of the subjective refraction of the test eye E can be obtained.

The above two examples can be combined to apply the following linear correction formula: SR = OR x c(CT, OR) + b(CT, OR). By substituting the objective refractive power measurement data (OR) acquired by the refraction measurement unit 10, the value (CT) indicated in the choroidal thickness data of the test eye E and the correction ratio c(CT, OR) corresponding to the measurement data (OR), and the value (CT) indicated in the thickness data and the measurement data (OR) into the correction formula, an estimate (SR) of the subjective refractive power of the test eye E can be obtained.

A fourth example of a process for estimating subjective refractive power based on choroidal thickness will be described. From the same viewpoint as in the second example, it is possible to divide the choroidal thickness value into a plurality of ranges, provide correction equations corresponding to each range, and selectively apply these correction equations. The correction equation in this example is a predetermined correction equation with the choroidal thickness and refractive power as variables, as described in the third example.

A specific example will be described. The data processing unit 50 in this example prestores two or more correction formulas corresponding to two or more ranges of choroidal thickness values. The data processing unit 50 selects a correction formula corresponding to the choroidal thickness data of the test eye E from among these correction formulas. Furthermore, the data processing unit 50 obtains an estimate of the subjective refractive power of the test eye E by inputting, for example, the measurement data of the objective refractive power acquired by the refraction measurement unit 10 and the choroidal thickness data of the test eye E into the selected correction formula.

A fifth example of a process for estimating subjective refractive power based on choroidal thickness will be described. Factors affecting the conversion of refractive power are not limited to choroidal thickness. For example, the refractive power may affect the conversion. For example, it may not be appropriate to apply the same conversion formula (correction formula) to both an eye with a particularly small refractive power and an eye with a particularly large refractive power. From this perspective, it is possible to divide the refractive power value into a plurality of ranges, provide correction formulas corresponding to each range, and selectively apply these correction formulas. Note that the correction formula in this example is a predetermined correction formula with the choroidal thickness and the refractive power as variables, as described in the third example.

A specific example will be described. In this example, the data processing unit 50 prestores two or more correction formulas corresponding to two or more ranges of refractive power values. The data processing unit 50 selects, from among these correction formulas, a correction formula that corresponds to the measurement data of the objective refractive power acquired by the refraction measurement unit 10. Furthermore, the data processing unit 50 obtains an estimate of the subjective refractive power of the test eye E by inputting, for example, the measurement data of the objective refractive power acquired by the refraction measurement unit 10 and the choroidal thickness data of the test eye E into the selected correction formula.

A sixth example of a process for estimating subjective refractive power based on choroidal thickness will be described. In this example, a combination of the fourth and fifth examples will be described. That is, the choroidal thickness values are divided into a plurality of ranges, and the refractive power values are divided into a plurality of ranges, and a correction formula is provided for each combination of the two ranges, and these correction formulas can be selectively applied. The correction formula in this example is a predetermined correction formula with the choroidal thickness and the refractive power as variables, as described in the third example.

A specific example will be described. First, for each combination of two or more ranges of choroidal thickness values and two or more ranges of refractive power values, a corresponding correction formula is prepared. In this example, four or more correction formulas are stored in the data processing unit 50. From these correction formulas, the data processing unit 50 selects a correction formula corresponding to a combination of choroidal thickness data of the test eye E and measurement data of the objective refractive power of the test eye E. Furthermore, the data processing unit 50 obtains an estimate of the subjective refractive power of the test eye E by inputting, for example, the measurement data of the objective refractive power of the test eye E and the choroidal thickness data of the test eye E into the selected correction formula.

A seventh example of a process for estimating subjective refractive power based on choroidal thickness will be described. The ophthalmic device 1 of this example further includes a function for acquiring axial length data of the subject's eye E (axial length data acquisition unit). The axial length data may be acquired, for example, by either measurement using an axial length measurement device or by receiving axial length data from an electronic medical record system or the like.

The method for measuring axial length may be, for example, a method using OCT as disclosed in Patent Documents 1 and 2. That is, the axial length can be obtained by identifying the corneal apex position and the retinal surface position based on OCT data and calculating the distance between these positions. Note that the method for measuring axial length is not limited to this, and may be, for example, another known method using ultrasound.

Now, the variables for linear correction are not limited to choroidal thickness and refractive power. In this example, the data processing unit 50 is configured to calculate an estimate of the subjective refractive power of the test eye E based on a predetermined correction formula with the choroidal thickness and axial length as variables, the objective refractive power measurement data acquired by the refraction measurement unit 10, the choroidal thickness data, and the axial length data.

In this example, the subjective refractive power is estimated by scaling (linear correction) the objective refractive power using choroidal thickness (CT) and axial length (AL) as variables.

The linear correction formula applicable in this example may be the following conversion formula for converting objective refraction (OR) to subjective refraction (SR): SR = OR + b(CT, AL). Here, b(CT, AL) is a function for determining the correction amount, with choroidal thickness (CT) and axial length (AL) as variables. By substituting the objective refraction measurement data (OR) acquired by the refraction measurement unit 10 and the correction amount b(CT, AL) corresponding to the value (CT) indicated in the choroidal thickness data of the test eye E and the axial length data (AL) into the correction formula, an estimate of the subjective refraction (SR) of the test eye E can be obtained.

Another linear correction formula that can be applied in this example is shown below: SR = OR x c (CT, AL). Here, c (CT, AL) is a function that determines the correction ratio, with choroidal thickness (CT) and axial length (AL) as variables. By substituting the objective refractive power measurement data (OR) acquired by the refraction measurement unit 10 and the correction ratio c (CT, AL) corresponding to the value (CT) indicated in the choroidal thickness data of the test eye E and the axial length data (AL) into the correction formula, an estimate (SR) of the subjective refractive power of the test eye E can be obtained.

The above two examples can be combined to apply the following linear correction formula: SR = OR x c(CT, AL) + b(CT, AL). By substituting the objective refractive power measurement data (OR) acquired by the refraction measurement unit 10, the correction ratio c(CT, AL) corresponding to the value (CT) indicated in the choroidal thickness data of the test eye E and the axial length data (AL), and the correction amount b(CT, AL) corresponding to the value (CT) indicated in the thickness data and the axial length data (AL) into the correction formula, an estimate (SR) of the subjective refractive power of the test eye E can be obtained.

An eighth example of a process for estimating subjective refractive power based on choroidal thickness will be described. From the same viewpoint as in the second example, it is possible to divide the choroidal thickness value into a plurality of ranges, provide correction equations corresponding to each range, and selectively apply these correction equations. The correction equation in this example is a predetermined correction equation with the choroidal thickness and axial length as variables, as described in the seventh example.

A specific example will be described. The data processing unit 50 in this example prestores two or more correction formulas corresponding to two or more ranges of choroidal thickness values. The data processing unit 50 selects a correction formula corresponding to the choroidal thickness data of the test eye E from among these correction formulas. Furthermore, the data processing unit 50 obtains an estimate of the subjective refractive power of the test eye E by inputting, for example, the measurement data of the objective refractive power acquired by the refraction measurement unit 10 and the choroidal thickness data of the test eye E into the selected correction formula.

A ninth example of a process for estimating subjective refractive power based on choroidal thickness will be described. Factors affecting the conversion of refractive power are not limited to choroidal thickness and refractive power. For example, axial length may affect the conversion. It is known that axial length affects refractive power. For example, eyes with particularly long axial lengths tend to be highly myopic. Therefore, it may not be appropriate to apply the same conversion formula (correction formula) to both eyes with particularly long and short axial lengths. From this perspective, it is possible to divide axial length values into multiple ranges, set correction formulas corresponding to each range, and selectively apply these correction formulas. The correction formula in this example is a predetermined correction formula with choroidal thickness and axial length as variables, as described in the seventh example.

A specific example will be described. In this example, the data processing unit 50 pre-stores two or more correction formulas corresponding to two or more ranges of axial length values. The data processing unit 50 selects from these correction formulas a correction formula that corresponds to the axial length data acquired by the axial length data acquisition unit. Furthermore, the data processing unit 50 obtains an estimate of the subjective refractive power of the test eye E by inputting, for example, the measurement data of the objective refractive power acquired by the refraction measurement unit 10 and the choroidal thickness data of the test eye E into the selected correction formula.

A tenth example of a process for estimating subjective refractive power based on choroidal thickness will be described. In this example, a combination of the eighth and ninth examples will be described. That is, the choroidal thickness values are divided into a plurality of ranges, and the axial length values are divided into a plurality of ranges, and a correction formula is provided for each combination of the two ranges, and these correction formulas can be selectively applied. The correction formula in this example is a predetermined correction formula with the choroidal thickness and axial length as variables, as described in the seventh example.

A specific example will be described. First, for each combination of two or more ranges of choroidal thickness values and two or more ranges of axial length values, a corresponding correction formula is prepared. In this example, four or more correction formulas are stored in the data processing unit 50. The data processing unit 50 selects, from among these correction formulas, a correction formula that corresponds to a combination of the choroidal thickness data of the test eye E and the axial length data of the test eye E. Furthermore, the data processing unit 50 obtains an estimate of the subjective refractive power of the test eye E by inputting, for example, measurement data of the objective refractive power of the test eye E and the choroidal thickness data of the test eye E into the selected correction formula.

An eleventh example of a process for estimating subjective refractive power based on choroidal thickness will be described. This example is a combination of the third and seventh examples. The data processing unit 50 in this example is configured to obtain an estimate of the subjective refractive power of the test eye E based on a predetermined correction equation including three variables, choroidal thickness, refractive power, and axial length, the measurement data of the objective refractive power acquired by the refraction measurement unit 10, the choroidal thickness data, and the axial length data.

In this example, the subjective refractive power is estimated by scaling (linear correction) the objective refractive power using the choroidal thickness (CT), objective refractive power (OR), and axial length (AL) as variables.

The linear correction formula applicable in this example may be the following conversion formula for converting the objective refraction power (OR) to the subjective refraction power (SR): SR = OR + b (CT, OR, AL). Here, b (CT, OR, AL) is a function for determining the correction amount, with the choroidal thickness (CT), the objective refraction power (OR), and the axial length (AL) as variables. The objective refraction power measurement data (OR) acquired by the refraction measurement unit 10 and the correction amount b (CT, OR, AL) corresponding to the value (CT) indicated in the choroidal thickness data of the test eye E, the measurement data (OR), and the axial length data (AL) are substituted into the correction formula, and an estimate of the subjective refraction power (SR) of the test eye E is obtained.

Although details are omitted, other linear correction formulas that can be applied in this example include SR = OR x c(CT, OR, AL) and SR = OR x c(CT, OR, AL) + b(CT, OR, AL). Here, c(CT, OR, AL) is a function that determines the correction ratio, with the choroidal thickness (CT), objective refraction (OR), and axial length (AL) as variables.

Although details will also be omitted, it is possible to divide the choroidal thickness value, refractive power value, and axial length value into multiple ranges, set a correction formula for each combination of these ranges, and selectively apply these correction formulas. The correction formula in this example is a predetermined correction formula with the choroidal thickness, refractive power, and axial length as variables.

<Operation>
The operation of the ophthalmic apparatus 1 according to the present embodiment will be described. An example of the operation of the ophthalmic apparatus 1 is shown in Fig. 2 and Fig. 3. The flowchart in Fig. 2 shows an example of the operation when the axial length data is not used, and the flowchart in Fig. 3 shows an example of the operation when the axial length data is used.

First, we will explain the operation example shown in Figure 2.

(S1: Objective refraction measurement)
In step S1 of this example, objective refraction measurement of the subject's eye E is performed using the refraction measurement unit 10 of the ophthalmic apparatus 1.

(S2: Fundus OCT scan)
In step S2 of the present example, an OCT scan is applied to the fundus Ef using the OCT section 20 of the ophthalmologic apparatus 1, and OCT data is acquired.

Note that an OCT scan may be performed before the objective refraction measurement, or the objective refraction measurement and the OCT scan may be performed in parallel.

Although not shown in the figures, the ophthalmologic device 1 may have a function of presenting a fixation target to the subject to guide the gaze of the subject's eye E. The fixation target may be an internal fixation target presented to the subject's eye E, or an external fixation target presented to the fellow eye. Objective refraction measurement and OCT scanning can be performed at the same fixation position.

(S3: Acquire layer position data from OCT data)
The layer position data acquisition part 40 acquires layer position data of the fundus Ef by analyzing the OCT data acquired in step S2.

(S4: Estimation of subjective refractive power)
The data processing unit 50 obtains an estimate of the subjective refractive power of the subject's eye E based on at least the measurement data of the objective refractive power of the subject's eye E obtained in step S1 and the layer position data obtained in step S3. Note that, by using a similar method, it is also possible to obtain a correction value of the objective refractive power different from the estimate of the subjective refractive power.

Next, the operation example shown in FIG. 3 will be described. In this example, the axial length data of the subject's eye E is referenced.

(S11: Objective refraction measurement)
In step S11 of this example, objective refraction measurement of the subject's eye E is performed using the refraction measurement unit 10 of the ophthalmic apparatus 1.

(S12: Fundus OCT scan)
In step S12 of the present example, an OCT scan is applied to the fundus Ef using the OCT section 20 of the ophthalmologic apparatus 1, and OCT data is acquired.

(S13: Acquire axial length data)
In step S13 of the present embodiment, axial length data of the subject's eye E is acquired using the axial length data acquisition unit of the ophthalmic apparatus 1.

The order and timing of performing the three steps of objective refraction measurement, OCT scanning, and axial length data acquisition can be arbitrary. In addition, objective refraction measurement, OCT scanning, and axial length measurement can be performed at the same fixation position.

(S14: Acquire layer position data from OCT data)
The layer position data acquisition part 40 acquires layer position data of the fundus Ef by analyzing the OCT data acquired in step S12.

(S15: Estimation of subjective refractive power)
The data processing unit 50 obtains an estimate of the subjective refractive power of the subject's eye E based on at least the measurement data of the objective refractive power of the subject's eye E obtained in step S11, the axial length data obtained in step S13, and the layer position data obtained in step S14. Note that, by using a similar method, it is also possible to obtain a correction value of the objective refractive power different from the estimate of the subjective refractive power.

Second Embodiment
In the first embodiment, a case where an estimate of subjective refraction power is obtained as refraction power data based on the choroidal thickness of the subject's eye has been described. As described above, the refraction power data may be an estimate of objective refraction power (or subjective refraction power) at a time different from the time when the objective refraction measurement is performed. In this embodiment, a case where an estimate of objective refraction power at a time different from the time when the objective refraction measurement is performed will be described.

In order to obtain an estimate of the subjective refractive power at a time different from the time when the objective refraction measurement was performed, for example, the following two steps can be applied: (First step) By executing the process according to this embodiment, an estimate of the objective refraction power at a time different from the time when the objective refraction measurement was performed is obtained; (Second step) By executing the process according to the first embodiment, the estimate of the objective refraction power obtained in the first step is converted into an estimate of the subjective refraction power. In addition, the process of obtaining an estimate of the subjective refraction power at a time different from the time when the objective refraction measurement was performed is not limited to this example.

In normal eyes, no significant diurnal variation in retinal thickness is observed, but choroidal thickness does vary significantly throughout the day, and is thought to vary throughout the day due to an inherent biorhythm. Correlations between the choroidal thickness value at a given time (baseline) and the range of variation in choroidal thickness, as well as correlations between refractive power and the range of variation in choroidal thickness have been reported (see, for example, Non-Patent Document 2). An example of an embodiment based on these findings is described below.

In the following description, the symbols used in the first embodiment will be used accordingly. In addition, in this embodiment, unless otherwise specified, the description of the same matters as in the first embodiment will be omitted, and the matters different from the first embodiment will be described in particular.

<Configuration>
An example of the configuration of an ophthalmic apparatus according to this embodiment is shown in Fig. 4. The ophthalmic apparatus 1A includes a refraction measurement unit 10, an OCT unit 20, and a computer 30A. The computer 30A includes a layer position data acquisition unit 40, a data processing unit 50A, a control unit 60, and a time recording unit 70A.

The refraction measurement unit 10, the OCT unit 20, the layer position data acquisition unit 40, and the control unit 60 may each be similar to the corresponding elements in the first embodiment.

The computer 30A executes various calculations and various controls to operate the ophthalmic device 1A. The computer 30A includes one or more processors and one or more storage devices. Various computer programs are stored in the storage devices, and the calculations and controls related to this example are realized by the processor operating based on the programs. In this example, with this configuration, the processor functions as each of the layer position data acquisition unit 40, the data processing unit 50A, the control unit 60, and the time recording unit 70A.

The time recording unit 70A records the time when the OCT unit 20 performs an OCT scan to obtain choroidal thickness data of the subject's eye E. This time is called the measurement time.

The time recording unit 70A includes a clock unit and a recording unit. The clock unit has a function of displaying the time. The clock unit includes, for example, a real-time clock, a high-precision event timer, a satellite positioning signal receiver, a base station signal receiver, etc.

The recording unit records the time presented by the clock unit when a specific event occurs. In other words, the recording unit records the time when a specific event occurs. The recording unit includes a processor that can access the clock unit, and a storage device in which the time data obtained by the processor from the clock unit is recorded.

As described above, the event whose occurrence time is recorded may be the time (measurement time) when the OCT unit 20 performs an OCT scan to obtain choroidal thickness data of the test eye E. Note that the measurement time is not limited to this, and may be, for example, the time when the refraction measurement unit 10 performs an objective refraction measurement to obtain the objective refraction power (measurement data) of the test eye E.

In a typical embodiment, the measurement by the refraction measurement unit 10 and the measurement by the OCT unit 20 can be performed at substantially the same time. "Substantially the same time" refers not only to simultaneous measurement, but also to measurement with a time difference that is acceptable in terms of the diurnal variation (biorhythm) of choroidal thickness.

The data processing unit 50A obtains an estimate of the refractive power of the test eye E at a specified time based on at least the measurement time recorded by the time recording unit 70A, the measurement data of the objective refractive power of the test eye E, and the choroidal thickness data of the test eye E. The specified time can be set arbitrarily, for example, by the user or the ophthalmic device 1A.

The data processing unit 50A can refer to standard data on the diurnal variation of choroidal thickness. The standard data is obtained, for example, by regression analysis using at least choroidal thickness as a variable. Variables other than choroidal thickness include refractive power, axial length, age, etc.

The regression analysis may be, for example, linear regression analysis or nonlinear regression analysis. An example of nonlinear regression analysis is periodic regression analysis based on trigonometric functions. Linear regression analysis is typically used to obtain standard data for a portion of a 24-hour period. This portion of the period is a period where linear approximation is possible, such as daytime or nighttime. Periodic regression analysis is typically used to obtain standard data over a period of time (e.g., the entire 24-hour period) where sufficient approximation is not possible using linear approximation.

When linear regression analysis is applied, the choroidal thickness variation ΔCT is expressed, for example, by the following formula: ΔCT = a × t, where t is the time and a is the slope of the regression line. This regression line is defined, for example, in a coordinate system in which the horizontal axis represents the time axis and the vertical axis represents the amount of variation in choroidal thickness.

When performing linear regression analysis using choroidal thickness (CT) as a variable, for example, the regression line ΔCT = a(CT) x t is used. When performing linear regression analysis using choroidal thickness (CT) and objective refraction (OR) as variables, for example, the regression line ΔCT = a(CT, OR) x t is used. Here, the objective refraction (OR) may be spherical power (S) or spherical equivalent (SE). When performing linear regression analysis using objective refraction (OR) as a variable, for example, the regression line ΔCT = a(OR) x t is used.

When periodic regression analysis is applied, the choroidal thickness variation ΔCT is expressed, for example, by the following formula: ΔCT = a × sin(t). Here, sin() is a sine function, t is time, and a is amplitude. This regression curve is defined, for example, in a coordinate system in which the horizontal axis represents the time axis and the vertical axis represents the amount of variation in choroidal thickness.

When performing a periodic regression analysis using choroidal thickness (CT) as a variable, for example, the regression curve ΔCT = a(CT) x sin(t) is used. When performing a periodic regression analysis using choroidal thickness (CT) and objective refraction (OR) as variables, for example, the regression curve ΔCT = a(CT, OR) x sin(t) is used. When performing a periodic regression analysis using objective refraction (OR) as a variable, for example, the regression curve ΔCT = a(OR) x sin(t) is used.

The regression lines and regression curves exemplified above are created in advance and used as standard data for the diurnal variation of choroidal thickness. The standard data is stored, for example, in the data processing unit 50A.

The data processing unit 50A may be configured to calculate an estimate of the refractive power at a specified time based on at least standard data on the diurnal variation of choroidal thickness, the measurement time, the objective refractive power measurement data, and the choroidal thickness data.

For example, the data processing unit 50A can obtain an estimate of the amount of change in refractive power based on the standard data, the measurement time, and the choroidal thickness data. Typically, the data processing unit 50A can obtain an estimate of the amount of change in refractive power by applying the measurement time and the thickness data to the standard data.

Here, the data processing unit 50A may be configured to perform, for example, a process of calculating an estimated value of the variation in choroidal thickness based on standard data, the measurement time, and thickness data, and a process of calculating an estimated value of the variation in refractive power based on the calculated estimated value of the variation in choroidal thickness. The former process is performed by applying the measurement time and thickness data to the standard data. The latter process is performed via a relational equation (predetermined) between the variation in choroidal thickness and the variation in refractive power. If it is calculated assuming that the variation in choroidal thickness corresponds to the variation in retina, for example, a variation in retina of 40 micrometers corresponds to a variation in refractive power of 0.1 diopters in a typical eye.

Furthermore, the data processing unit 50A can obtain an estimate of the refractive power at a specified time based on the obtained estimate of the amount of fluctuation in the refractive power and the measurement data of the objective refractive power. Typically, the data processing unit 50A can obtain an estimate of the refractive power at a specified time by adding the obtained estimate of the amount of fluctuation in the refractive power to the value indicated in the measurement data of the objective refractive power.

As mentioned above, it has been reported that there is a correlation between the choroidal thickness value at a specific time (baseline) and the range of variation in choroidal thickness. From this perspective, it is possible to configure the system to provide multiple standard data according to the choroidal thickness value at a specific reference time (e.g., 9:00 a.m.) and to selectively use them. Here, each of the multiple standard data may be created by regression analysis using the refractive power (OR) as a variable.

The data processing unit 50A prestores two or more standard data items corresponding to two or more ranges of choroidal thickness values at a predetermined reference time. The data processing unit 50A selects, from among these standard data items, the standard data item corresponding to the choroidal thickness data of the subject eye E.

Furthermore, the data processing unit 50A can obtain an estimate of the refractive power at a specified time based on the selected standard data, the measurement time recorded by the time recording unit 70A, the measurement data of the objective refractive power of the test eye E, and the choroidal thickness data of the test eye E. This process is performed in the manner described above.

<Operation>
An example of the operation of the ophthalmic apparatus 1A according to this embodiment is shown in FIG.

(S21: Objective refraction measurement)
In step S21 of this example, objective refraction measurement of the subject's eye E is performed using the refraction measurement unit 10 of the ophthalmic apparatus 1A.

(S22: Fundus OCT scan)
In step S22 of the present example, an OCT scan is applied to the fundus Ef using the OCT section 20 of the ophthalmologic apparatus 1A, and OCT data is acquired.

The order and timing of performing the objective refraction measurement and OCT scan are arbitrary. In addition, the objective refraction measurement and OCT scan can be performed at the same fixation position.

(S23: Record the measurement time)
In step S23 of this example, the measurement time is recorded using the time recording unit 70A of the ophthalmic apparatus 1A.

(S24: Acquire layer position data from OCT data)
The layer position data acquisition part 40 acquires layer position data of the fundus Ef by analyzing the OCT data acquired in step S22.

(S25: Estimation of refractive power at a given time)
The data processing unit 50A calculates an estimate of the refractive power of the test eye E at a specified time based on at least the measurement time recorded in step S23, the measurement data of the objective refractive power acquired in step S21, and the choroidal thickness data calculated from the layer position data acquired in step S24.

<Action and Effects>
The operation and effects of the ophthalmic apparatus according to some exemplary embodiments will be described.

An ophthalmic device (1, 1A) according to an exemplary embodiment includes a refraction measurement unit (10), an OCT unit (20), a layer position data acquisition unit (40), and a data processing unit (50, 50A). The refraction measurement unit objectively measures the refractive power of the test eye. The OCT unit acquires OCT data by applying an OCT scan to the fundus of the test eye. The layer position data acquisition unit acquires layer position data including position data of one or more layers of the fundus by analyzing the OCT data. The data processing unit generates refractive power data of the test eye based at least on the measurement data and layer position data acquired by the refraction measurement unit.

With this type of ophthalmologic device, new refractive power data can be obtained based on the measured value of the objective refractive power of the test eye and the position of the fundus layer. Therefore, it is possible to obtain refractive power data that takes into account the position of the fundus layer.

In the ophthalmic device (1, 1A) according to the exemplary embodiment, the layer position data acquisition unit (40) may be configured to acquire layer position data including position data of a first layer and position data of a second layer of the fundus. Furthermore, the data processing unit (50, 50A) may be configured to determine distance data between the first layer and the second layer based on the layer position data, and to generate refractive power data of the subject's eye based at least on the distance data and the measurement data of the objective refractive power.

With this type of ophthalmic device, new refractive power data can be obtained based on the distance between the two layers of the fundus and the measurement data of the objective refractive power. Therefore, it is possible to obtain refractive power data that takes into account the distance between the two layers of the fundus.

In the ophthalmic device (1, 1A) according to the exemplary embodiment, the layer position data acquisition unit (40) may be configured to identify a combination of the anterior and posterior choroidal surfaces of the fundus as a combination of a first layer and a second layer, and to acquire layer position data including position data of the anterior choroidal surface and position data of the posterior choroidal surface. In addition, the data processing unit (50, 50A) may be configured to execute a process of obtaining choroidal thickness data as distance data between the first layer and the second layer, and a process of generating refractive power data of the subject's eye based at least on the measurement data of the objective refractive power and the choroidal thickness data.

With this type of ophthalmic device, new refractive power data can be obtained based on choroidal thickness data and objective refractive power measurement data. Therefore, it is possible to obtain refractive power data that takes into account the choroidal thickness.

In the ophthalmic device (1) according to the exemplary embodiment, the data processing unit (50) may be configured to obtain an estimate of the subjective refractive power of the subject's eye (refractive power data) based at least on the objective refractive power measurement data and the choroidal thickness data. Note that in some exemplary embodiments, it is possible to obtain a correction value of the objective refractive power, which is different from the estimate of the subjective refractive power, by a similar method.

With such an ophthalmic device, the subjective refractive power of the examinee's eye can be estimated based on choroidal thickness data and objective refractive power measurement data. Therefore, it is possible to obtain the subjective refractive power taking into account the choroidal thickness. Typically, it is possible to estimate the subjective refractive power from the objective refractive power obtained by objective refraction measurement using near-infrared light by excluding the influence of the choroid, etc. The same applies to the correction of the objective refractive power, which is different from the estimation of the subjective refractive power.

In the ophthalmic device (1) according to the exemplary embodiment, the data processing unit (50) may be configured to calculate an estimate of the subjective refractive power based on a predetermined correction formula with at least the choroidal thickness as a variable, measurement data of the objective refractive power of the test eye, and choroidal thickness data of the test eye. Note that in some exemplary embodiments, it is possible to calculate a correction value of the objective refractive power that is different from the estimate of the subjective refractive power by a similar method.

With this type of ophthalmic device, it is possible to estimate the subjective refractive power with high accuracy and precision by taking into account differences in choroidal thickness. The same applies to the correction of the objective refractive power, which is different from the estimation of the subjective refractive power.

In the ophthalmic device (1) according to the exemplary embodiment, the data processing unit (50) may be configured to select a correction formula corresponding to the choroidal thickness data of the test eye from among two or more correction formulas corresponding to two or more ranges of choroidal thickness values, and obtain an estimate of the subjective refractive power by inputting at least the objective refractive power measurement data into the selected correction formula. Note that in some exemplary embodiments, it is possible to obtain a correction value of the objective refractive power different from the estimate of the subjective refractive power by a similar method.

With such an ophthalmic device, it is possible to improve the accuracy and precision of the estimation of subjective refractive power. The same applies to the correction of objective refractive power, which is different from the estimation of subjective refractive power.

In the ophthalmic device (1) according to the exemplary embodiment, the data processing unit (50) may be configured to calculate an estimate of the subjective refractive power of the subject's eye based on a predetermined correction equation having at least choroidal thickness and refractive power as variables, the objective refractive power measurement data, and the choroidal thickness data. Note that in some exemplary embodiments, it is possible to calculate a correction value for the objective refractive power that is different from the subjective refractive power estimate by a similar method.

With such an ophthalmic device, it is possible to improve the accuracy and precision of the estimation of subjective refractive power. The same applies to the correction of objective refractive power, which is different from the estimation of subjective refractive power.

In the ophthalmic device (1) according to the exemplary embodiment, the data processing unit (50) may be configured to select a correction formula corresponding to the choroidal thickness data of the test eye from among two or more correction formulas corresponding to two or more ranges of choroidal thickness values, and obtain an estimate of the subjective refractive power by inputting at least the objective refractive power measurement data into the selected correction formula. Note that in some exemplary embodiments, it is possible to obtain a correction value of the objective refractive power different from the estimate of the subjective refractive power by a similar method.

In addition, in the ophthalmic device (1) according to the exemplary embodiment, the data processing unit (50) may be configured to select a correction formula corresponding to the measurement data of the objective refractive power of the test eye from among two or more correction formulas corresponding to two or more ranges of refractive power values, and obtain an estimate of the subjective refractive power by inputting at least the measurement data of the objective refractive power into the selected correction formula. Note that in some exemplary embodiments, it is possible to obtain a correction value of the objective refractive power that is different from the estimate of the subjective refractive power by a similar method.

In addition, in the ophthalmic device (1) according to the exemplary embodiment, the data processing unit (50) may be configured to select a correction formula corresponding to a combination of the choroidal thickness data of the test eye and the measurement data of the objective refractive power of the test eye from among four or more correction formulas each corresponding to a combination of two or more ranges of choroidal thickness values and two or more ranges of refractive power values, and obtain an estimate of the subjective refractive power by inputting at least the measurement data of the objective refractive power into the selected correction formula. Note that in some exemplary embodiments, it is possible to obtain a correction value of the objective refractive power different from the estimate of the subjective refractive power by a similar method.

With this type of ophthalmic device, it is possible to further improve the accuracy and precision of the estimation of subjective refractive power. The same applies to the correction of objective refractive power, which is different from the estimation of subjective refractive power.

The ophthalmic device (1) according to the exemplary embodiment may further include an axial length data acquisition unit (20, 30) that acquires axial length data of the subject's eye. In addition, the data processing unit (30) may be configured to calculate an estimate of the subjective refractive power based on a predetermined correction equation with at least the choroidal thickness and the axial length as variables, the objective refractive power measurement data, the choroidal thickness data, and the axial length data. Note that in some exemplary embodiments, it is possible to calculate a correction value of the objective refractive power that is different from the estimate of the subjective refractive power by a similar method.

With this type of ophthalmic device, it is possible to estimate the subjective refractive power with high accuracy and precision by taking into account differences in choroidal thickness and axial length. The same applies to the correction of the objective refractive power, which is different from the estimation of the subjective refractive power.

In the ophthalmic device (1) according to the exemplary embodiment, the data processing unit (50) may be configured to select a correction formula corresponding to the choroidal thickness data of the test eye from among two or more correction formulas corresponding to two or more ranges of choroidal thickness values, and obtain an estimate of the subjective refractive power by inputting at least the measurement data of the objective refractive power of the test eye into the selected correction formula. Note that in some exemplary embodiments, it is possible to obtain a correction value of the objective refractive power different from the estimate of the subjective refractive power by a similar method.

In addition, in the ophthalmic device (1) according to the exemplary embodiment, the data processing unit (50) may be configured to select a correction formula corresponding to the axial length data of the subject's eye from among two or more correction formulas corresponding to two or more ranges of axial length values, and obtain an estimate of the subjective refractive power by inputting at least the measurement data of the objective refractive power of the subject's eye into the selected correction formula. Note that in some exemplary embodiments, it is possible to obtain a correction value of the objective refractive power that is different from the estimate of the subjective refractive power by a similar method.

In addition, in the ophthalmic device (1) according to the exemplary embodiment, the data processing unit (50) may be configured to select a correction formula corresponding to a combination of the choroidal thickness data of the test eye and the axial length data of the test eye from among four or more correction formulas corresponding to combinations of two or more ranges of choroidal thickness values and two or more ranges of axial length values, respectively, and to obtain an estimate of the subjective refractive power by inputting at least the measurement data of the objective refractive power of the test eye into the selected correction formula. Note that in some exemplary embodiments, it is possible to obtain a correction value of the objective refractive power different from the estimate of the subjective refractive power by a similar method.

With this type of ophthalmic device, it is possible to further improve the accuracy and precision of the estimation of subjective refractive power. The same applies to the correction of objective refractive power, which is different from the estimation of subjective refractive power.

The ophthalmic device (1) according to the exemplary embodiment may further include an axial length data acquisition unit (20, 30) that acquires axial length data of the subject's eye. In addition, the data processing unit (50) may be configured to calculate an estimate of the subjective refractive power based on a predetermined correction equation having at least the choroidal thickness, refractive power, and axial length as variables, measurement data of the objective refractive power of the subject's eye, choroidal thickness data of the subject's eye, and axial length data of the subject's eye. Note that in some exemplary embodiments, a correction value of the objective refractive power different from the estimate of the subjective refractive power can be calculated by a similar method.

With this type of ophthalmic device, it is possible to estimate the subjective refractive power with high accuracy and precision by taking into account differences in choroidal thickness, refractive power, and axial length. The same applies to the correction of the objective refractive power, which is different from the estimation of the subjective refractive power.

The ophthalmic device (1A) according to the exemplary embodiment may further include a time recording unit (70A) that records the measurement time, which is the time when the OCT unit (20) performs an OCT scan to obtain choroidal thickness data of the test eye. In addition, the data processing unit (50A) may be configured to obtain an estimate of the refractive power of the test eye at a specified time (refractive power data) based on at least the measurement time, the measurement data of the objective refractive power of the test eye, and the choroidal thickness data of the test eye.

With this type of ophthalmic device, it is possible to estimate the refractive power of the test eye at a time different from the measurement time by taking into account the choroidal thickness.

In an ophthalmic device (1A) according to an exemplary embodiment, the data processing unit (50A) may be configured to obtain an estimate of the refractive power at a specified time based on at least standard data on the diurnal variation of choroidal thickness, the measurement time, measurement data of the objective refractive power of the test eye, and choroidal thickness data of the test eye.

Furthermore, the data processing unit (50A) may be configured to obtain an estimate of the amount of variation in refractive power based on at least standard data on the diurnal variation in choroidal thickness, the measurement time, and the choroidal thickness data of the test eye, and to obtain an estimate of the refractive power at a specified time based on the obtained estimate of the amount of variation and the measurement data of the objective refractive power of the test eye.

Furthermore, the data processing unit (50A) may be configured to obtain an estimate of the amount of variation in choroidal thickness based on at least the standard data, the measurement time, and the choroidal thickness data of the test eye, obtain an estimate of the amount of variation in refractive power based on the obtained estimate of the amount of variation in choroidal thickness, and obtain an estimate of the refractive power at a specified time based on the obtained estimate of the amount of variation in refractive power and the measurement data of the objective refractive power of the test eye.

With this type of ophthalmic device, it is possible to estimate the refractive power of the test eye at a time different from the measurement time with high accuracy and precision by taking into account the diurnal variation in standard choroidal thickness.

In an ophthalmic device (1A) according to an exemplary embodiment, the data processing unit (50A) may be configured to select standard data corresponding to the choroidal thickness data of the test eye from among two or more standard data corresponding to two or more ranges of choroidal thickness values at a predetermined reference time, and to obtain an estimate of the refractive power at the predetermined time based on the selected standard data, the measurement time, the measurement data of the objective refractive power of the test eye, and the choroidal thickness data of the test eye.

With such an ophthalmic device, it is possible to estimate the refractive power at a time different from the measurement time with higher accuracy and precision.

According to some exemplary embodiments, position information (height information) of a particular layer of the fundus (retina, choroid, sclera) can be used to estimate the subjective refractive power from objective refractive power measurement data (or, more generally, to correct the objective refractive power) or to estimate the refractive power at a different time of day from data obtained from an objective refraction measurement performed at a certain time. The position information of a particular layer may be the thickness of a particular fundus tissue (e.g., choroidal thickness).

According to some exemplary embodiments, a refractive power value is obtained that takes into account the position of the fundus tissue (such as the retina) and the choroidal thickness. In particular, a refractive power value is obtained that takes into account the diurnal variation of the choroidal thickness.

This makes it possible to prescribe eyeglasses etc. that are appropriate for each time of day, such as refractive powers suitable for daytime and nighttime. It is also possible to prescribe eyeglasses etc. that are not overcorrected at all times of day. In particular, overcorrection in myopic eyes requires constant accommodation when viewing at a distance, which may cause the axial length to elongate due to the strain of accommodation.

It is also possible to calculate and present a range of refractive power taking into account diurnal variation.

In this way, some exemplary embodiments can solve various problems inherent in conventional eye refraction measurements.

The above-described embodiments are merely examples. Any modifications (omissions, substitutions, additions, etc.) may be made within the scope of the present invention.

The methods described in the exemplary embodiments (such as an information processing method and a method for controlling an ophthalmic device) can be executed by an ophthalmic device or a computer. Also, a program for causing a computer to execute the method can be provided. Also, it is possible to create a computer-readable non-transitory recording medium on which such a program is recorded. This non-transitory recording medium may be in any form, and examples include a magnetic disk, an optical disk, a magneto-optical disk, and a semiconductor memory.

Reference Signs List 1 Ophthalmic apparatus 1A Ophthalmic apparatus 10 Refraction measurement unit 20 OCT unit 30 Computer 30A Computer 40 Layer position data acquisition unit 50 Data processing unit 50A Data processing unit 60 Control unit 70A Time recording unit

Claims (6)

A refraction measurement unit that objectively measures the refractive power of the subject's eye;
an optical coherence tomography (OCT) unit that applies an OCT scan to a fundus of the subject's eye to obtain OCT data;
a time recording unit that records a measurement time, which is a time when the OCT unit performs the OCT scan;
A layer position data acquisition unit that acquires layer position data including position data of the front surface of the choroid of the fundus and position data of the rear surface of the choroid by analyzing the OCT data;
a data processing unit that calculates choroidal thickness data based on the layer position data, and further calculates an estimated refractive power of the subject's eye at a predetermined time based on standard data of diurnal variation in choroidal thickness obtained by periodic regression analysis using at least choroidal thickness as a variable, the measurement time recorded by the time recording unit, the measurement data acquired by the refraction measurement unit, and the thickness data ,
The data processing unit includes:
determining an estimated value of the amount of variation in choroidal thickness based on the standard data, the measurement time, and the thickness data;
calculating an estimated value of the variation in refractive power based on the estimated value of the variation in choroidal thickness and a previously obtained relational expression between the variation in choroidal thickness and the variation in refractive power;
determining the estimated value of the refractive power of the subject's eye at the predetermined time based on the estimated value of the amount of variation in the refractive power and the measurement data;
Ophthalmic equipment. The data processing unit includes:
Selecting standard data corresponding to the thickness data from among two or more standard data corresponding to two or more ranges of choroidal thickness values at a predetermined reference time;
determining the estimated value of the amount of variation in the choroidal thickness based on the selected standard data, the measurement time , and the thickness data;
The ophthalmic device of claim 1 . The measurement data is either spherical power data or spherical equivalent power data.
3. An ophthalmic apparatus according to claim 1 or 2 . The standard data is a sine function with time as a variable, the amplitude of which is at least a variable of choroidal thickness.
The ophthalmic device according to any one of claims 1 to 3 . The standard data is a sine function with time as a variable, the amplitude of which is a function of choroidal thickness and objective refractive power.
5. An ophthalmic device according to claim 4 . the data processing unit obtains an estimated value of subjective refractive power based on the estimated value of the refractive power of the subject's eye at the predetermined time.
The ophthalmic device according to any one of claims 1 to 5 .

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