JP6831171B2 - Axial axis length measuring device, eyeball shape information acquisition method, and eyeball shape information acquisition program - Google Patents

Description

The present disclosure relates to an eye axis length measuring device for measuring the axial length of an eye to be inspected, an eyeball shape information acquisition method for acquiring eyeball shape information, and an eyeball shape information acquisition program.

Non-contact axial length measurement that has a measurement optical system that projects measurement light onto the eye to be inspected and detects the reflected light, and optically measures the axial length of the eye to be inspected using interference light. The device is known (see Patent Document 1).

Japanese Unexamined Patent Publication No. 2005-342204

However, the conventional axial length measuring device only measures at one point, and is insufficient for confirming a lesion or the like due to deformation of the eyeball shape of the eye to be inspected.

In view of the above problems, it is a technical subject of the present disclosure to provide an axial length measuring device capable of confirming the eyeball shape of an eye to be inspected, an eyeball shape information acquisition method, and an eyeball shape information acquisition program.

In order to solve the above problems, the present disclosure is characterized by having the following configurations.

(1) An interfering optical system for detecting an interference signal between the measurement light irradiated to the eye to be inspected and the reference light is provided, and the interfering optical system receives the corneal reflected light and the fundus reflected light by the measured light. An axial length measuring device that measures the axial length, which is the distance from the corneal membrane of the eye to be inspected to the fundus of the eye. The measurement position of the axial length on the eye to be inspected is set with the pupil of the eye to be inspected as a fulcrum. The measurement position changing means for changing to a plurality of measurement positions including the ear side and the nasal side of the eye bottom and the acquisition means for acquiring the axial length based on the interference signal from the interference optical system are provided. The acquisition means acquires the axial length at a plurality of measurement positions including the ear side and the nasal side, which are changed by the measurement position changing means, and at a plurality of measurement positions including the ear side and the nasal side. It is characterized in that the eyeball shape information of the eye to be inspected is acquired based on the axial length.
(2) A method for acquiring eyeball shape information, in which the eye to be inspected is irradiated at a plurality of measurement positions including the ear side and the nose side of the fundus of the eye with the pupil of the eye to be inspected as a fulcrum on the same eye to be inspected. The distance from the corneum of the eye to be inspected to the fundus of the eye, which is measured by receiving the reflected light of the corneal membrane and the reflected light of the fundus of the eye by the interference optical system that detects the interference signal between the measurement light and the reference light. An axial length acquisition step for acquiring the axial length, and a shape information acquisition step for acquiring eyeball shape information of the eye to be inspected based on the axial length acquired in the acquisition step.
It is characterized by including.
(3) An eyeball shape information acquisition program executed by a control device that controls the operation of the eyeball shape information acquisition device, and by being executed by the processor of the control device, the eyeball to be inspected is subjected to the same eye. Corneal reflection by the measurement light by an interference optical system that detects the interference signal between the measurement light and the reference light applied to the eye to be inspected at a plurality of measurement positions including the ear side and the nasal side of the eye bottom with the pupil as a fulcrum. An axial length acquisition step for acquiring the axial length, which is the distance from the corneum of the eye to be inspected to the fundus , measured by receiving light and reflected light from the fundus, and the axial length acquired in the acquisition step. It is characterized in that the eyeball shape information acquisition device executes the shape information acquisition step of acquiring the eyeball shape information of the eye to be inspected based on the length.

It is the schematic which shows the optical system of this apparatus. It is a figure for demonstrating the movement of the fixation lamp. It is a flowchart which shows the control operation of this apparatus. It is a figure for demonstrating the kind of eyeball deformation. It is a figure for demonstrating the calculation of the eyeball shape. It is a figure which shows an example of the screen displayed on the display part. It is a figure for demonstrating the calculation correction of the eyeball shape using the corneal shape. It is a figure for demonstrating another calculation method of an eyeball shape. It is the schematic which shows the optical system of 2nd Example. It is a figure for demonstrating the light guide optical system of 2nd Example. It is a figure which shows an example of the tomographic image acquired in the 2nd Example.

<Overview>
Hereinafter, the outline of the present embodiment will be described with reference to FIGS. 1 to 11. The axial length measuring device of the present embodiment can acquire eyeball shape information of the eye to be inspected. For example, the axial length measuring device has a first measurement mode (eye axis length measurement mode) for measuring the axial length of the eye to be inspected and a second measurement mode (eyeball shape information acquisition mode) for acquiring eyeball shape information of the eye to be inspected. ), You can select the mode and set the measurement operation.

The axial length measuring device includes, for example, an interference optical system (for example, a light projecting optical system 10, a light receiving optical system 20, etc.) and a measuring position changing means (for example, in the present embodiment, a control unit 80, an optometry optical system). 50 and the like) and acquisition means (for example, in the present embodiment, the control unit 80 and the like). For example, the interference optical system may detect an interference signal between the measurement light and the reference light applied to the eye to be inspected.
For example, in the present device, when the second measurement mode is set, the acquisition means acquires the axial lengths at a plurality of different measurement positions changed by the measurement position changing means, and the axial lengths at the plurality of measurement positions. Based on the above, the eyeball shape information of the eye to be inspected is acquired.

For example, the measurement position changing means changes the measurement position of the axial length on the eye to be inspected. For example, the measurement position changing means may be configured to change the fixation position of the eye to be inspected and change the measurement position of the axial length. In this case, for example, in the present embodiment, the measurement position changing means includes a configuration in which the fixation position is changed by using the fixation position changing means. For example, the optometry position changing means controls the optometry optical system 50 (for example, the optometry light source 51, the driving unit 52, etc.) to change the optometry position. For example, as the fixation position changing means, there is a configuration for controlling the lighting position of the fixation light source 51. Further, for example, as the fixation position changing means, there is a configuration in which the fixation light source 51 is moved. Further, for example, as the fixation position changing means, there is a configuration in which the fixation light beam emitted from the fixation light source 51 is scanned. In this way, the measurement position changing means may change the measurement position of the axial length.

Further, for example, as the measurement position changing means, the measurement of the axial length is changed by scanning the measurement light from the interference optical system on the eye to be inspected by a scanning optical system (for example, scanning optical system 123 or the like). May be good.

Further, for example, as the measurement position changing means, the measurement position of the axial length may be changed by adjusting the relative position between the apparatus main body containing the interference optical system and the eye to be inspected. In this case, for example, as a configuration for adjusting the relative position between the device main body and the eye to be inspected, the device main body is moved with respect to the eye to be inspected, and the jaw stand supporting the jaw of the subject is attached to the device main body. A moving configuration, etc. may be used.

For example, the measurement position changing means can be set to an arbitrary number of measurement positions such as two different measurement positions and three different measurement positions as a plurality of different measurement positions. For example, when the measurement position changing means changes the measurement position to at least three different measurement positions, the acquisition means is more than acquiring the eyeball shape information based on the two axial lengths having different measurement positions. Eyeball shape information can be reliably acquired.

More specifically, for example, the measurement position changing means changes the measurement position as at least three different measurement positions to at least the first measurement position where the reference axis of the eye to be inspected and the measurement optical axis coincide with each other. You may do so. By measuring the axial length of the reference axis of the eye to be inspected, it is easy to compare with the axial length of the normal eye measured separately.

In the following description, the reference axis of the eye to be inspected will be described as the visual axis of the eye to be inspected, but the present invention is not limited to this. For example, the reference axis of the eye to be inspected may be the optical axis of the eye to be inspected. Here, the visual axis of the eye to be inspected is, for example, a line connecting the point of gaze (for example, the fixation position) and the fovea centralis of the eye. The optical axis of the eye to be inspected is, for example, a line passing through the center of curvature of all the optical systems of the eye (for example, the cornea, the crystalline lens, etc.), and is different from the visual axis. For example, when the reference axis is the optical axis of the eye to be inspected, the measurement position changing means may set the measurement position on the optical axis of the eye to be inspected by shifting the measurement position by a predetermined amount with respect to the visual axis. .. More specifically, for example, when the measurement position is set using fixation, the presentation position of fixation is shifted by a predetermined amount from the presentation position of fixation when the reference axis is the visual axis. The optical axis of the interference optical system can be aligned with the optical axis of the optometry. As the predetermined amount, an amount that deviates from the visual axis and the optical axis can be generally used as the predetermined amount for shifting the fixation.

The measurement position changing means includes, for example, in addition to the first measurement position, a second measurement position located in a region on one side of the axis passing through the first measurement position, and a third measurement located in the other region. The position may be changed to. For example, the axis passing through the first measurement position is set in a direction such as a horizontal direction, a vertical direction, and an oblique direction (a direction between the horizontal direction and the vertical direction).

For example, the first measurement position, the second measurement position, and the third measurement position may be set on one meridian. That is, the first measurement position, the second measurement position, and the third measurement position may be set side by side in the horizontal direction, the vertical direction, and the diagonal direction (the direction between the horizontal direction and the vertical direction). Here, for example, the meridian may be a curve of the cut end when the eyeball is cut on a plane including the visual axis of the eyeball. That is, for changing the measurement position, for example, the measurement position may be changed so that the first measurement position located on the visual axis and the second measurement position and the third measurement position are linearly aligned. As described above, when the measurement position is located on one meridian, the acquisition means can easily acquire the eyeball shape information. For example, the acquisition means can easily perform calculations such as when the eyeball shape is approximated by an ellipse.

For example, the second measurement position and the third measurement position may be symmetrical about the axis passing through the first measurement value. This makes it easier for the examiner to confirm the symmetry of the eyeball shape of the eye to be examined. The symmetry may be symmetry in the horizontal direction (left-right symmetry), symmetry in the vertical direction (vertical symmetry), or symmetry in the diagonal direction.

For example, the measurement position changing means may be set as the second measurement position and the third measurement position at a position swirled around a reference position in the eye as a rotation point. For example, as the second measurement position, the measurement light of the interference optical system is located at a position shifted to the right with respect to the first measurement position in the anterior segment and at a position shifted to the left with respect to the first measurement position in the fundus. Is irradiated. Further, for example, the third measurement position is located at a position shifted to the left with respect to the first measurement position in the anterior segment of the eye, and at a position shifted to the right with respect to the first measurement position in the fundus. The measurement light is irradiated.

For example, the eyeball shape information is information that enables comparison of the axial length results at each measurement position (for example, information in which a plurality of measurement positions and the axial lengths acquired at the measurement positions are associated with each other, and a plurality of information. The shape of the eyeball is calculated from the axial length difference information of the eye to be inspected with respect to the axial length information of the normal eye, and the axial length result at each measurement position. The calculated calculation result information (for example, an approximate expression showing the eyeball shape, a graphic showing the eyeball shape, information classifying the result of the eyeball shape, etc.) may be used. The eyeball shape information is not limited to the outer surface shape of the eyeball, but may be information on the inner surface shape.

For example, the information associated with a plurality of measurement positions and the axial lengths acquired at the measurement positions may be configured such that the axial lengths acquired at each measurement position are displayed on the same screen. Further, for example, the display may show each measurement position and the measurement result of each axial length may be displayed.

For example, as the difference information of the axial lengths compared at a plurality of measurement positions, the difference value of the axial lengths at each measurement position with respect to the first measurement position may be displayed. Further, for example, the difference value between the second measurement position and the third measurement position may be displayed.

For example, the difference information of the axial length of the eye to be inspected with respect to the axial length information of the normal eye is to compare the database stored in the storage unit with the axial length obtained by measuring the eye to be inspected. May be obtained by. In this case, for example, the axial length of the normal eye measured at a plurality of measurement positions may be stored as a database in the storage unit (for example, the memory 85).
Further, for example, the classification information of the eyeball shape may be a determination result of determining which type the eyeball shape is classified when the axial length is deformed due to a disease or the like. For example, the acquisition means determines the type of eyeball shape of the eye to be inspected based on the axial lengths at a plurality of measurement positions, and acquires the determination result as the eyeball shape information of the eye to be inspected. The eyeball deformed due to a disease or the like is classified into four shapes, for example, a nasal protruding type, an ear protruding type, a spindle type, and a barrel type.

Further, the acquisition means may obtain an ellipse that approximates the shape of the eye to be inspected based on the axial lengths at the three measurement positions, and classify the eyeball shape according to the ratio of the minor axis to the major axis of the ellipse.

Further, the axial length is measured at at least three measurement positions on at least two meridian lines, and the shape of the eye to be inspected is based on the axial length at at least three measurement positions on each measured meridian. You may find an ellipse that approximates. Then, the eyeball shape may be classified based on the ratio of the minor axis to the major axis on at least two meridian lines.

<Example>
Hereinafter, examples will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of an optical system of the axial length measuring device according to the present embodiment. In this embodiment, the depth direction of the eye to be examined will be described as the Z direction (optical axis L1 direction), the horizontal direction will be described as the X direction, and the vertical direction will be described as the Y direction in a plane perpendicular to the depth direction.

<Interference optical system>
The interferometric optical system measures, for example, the axial length of the eye to be inspected. The interference optical system of this embodiment is, for example, a time domain type interference optical system. Of course, it is not limited to Time-domain OCT (TD-OCT), and may be a Fourier domain type interference optical system such as Spectral-domain OCT (SD-OCT) or Swept-source OCT (SS-OCT).

The interference optical system mainly includes, for example, a light source 1, a beam splitter 5, a light projecting optical system (irradiation optical system) 10, a light receiving optical system 20, and an optical path length changing member. The light source 1 may emit low coherent light, for example. The beam splitter 5 may split the emitted light into a first split light and a second split light, for example. For example, the projection optical system 10 may irradiate the first divided light toward the fundus of the eye to be inspected. The light receiving optical system 20 may include, for example, a light receiving element 21. The light receiving element 21 synthesizes, for example, the first divided light reflected by the fundus of the eye to be inspected and the second divided light to receive light. The optical path changing member may be, for example, a triangular prism 7. The optical path changing member may be movably arranged in one of the optical paths by the drive unit 71 in order to change the optical path lengths of the first divided light and the second divided light. The interference optical system measures the axial length of the eye to be inspected based on the light receiving signal output from the light receiving element 21.

The specific configuration of the above-mentioned optical system will be described below. The irradiation optical system 10 is arranged, for example, to irradiate the cornea to be inspected and the fundus of the eye to be inspected with measurement light. The irradiation optical system 10 includes, for example, a measurement light source 1 (for example, SLD), a collimator lens 3, a beam splitter 5, a first triangular prism (corner cube) 7, a second triangular prism 9, and a polarizing beam splitter 11. It has a 1/4 wave plate 13, a dichroic mirror 15, and an inspection window 17.

The measurement light source 1 may emit low coherent light, for example. The collimator lens 3 uses a light flux emitted from the measurement light source 1 as a parallel light flux. The beam splitter 5 may split the light emitted from the light source 1. The first triangular prism 7 may be arranged in the transmission direction of the beam splitter 5, and the second triangular prism 9 may be arranged in the reflection direction of the beam splitter 5.

The light receiving optical system 20 may be arranged to receive, for example, the corneal reflex light due to the measurement light emitted by the irradiation optical system 10 and the interference light due to the fundus reflected light. The light receiving optical system 20 includes, for example, an inspection window 17, a dichroic mirror 15, a quarter wave plate 13, a polarizing beam splitter 11, a condenser lens 19, and a light receiving element 21. This device detects the interference light of the reflected light on the cornea and the reflected light on the fundus by the light receiving element 21.

The triangular prism 7 is used as an optical path length changing member for changing the optical path length, and is linearly moved in the optical axis direction with respect to the beam splitter 5 by driving a drive unit 71 (for example, a motor). In this case, the optical path length changing member may be a triangular mirror. The drive position of the prism 7 may be detected by a position detection sensor 72 (for example, a potentiometer, an encoder, etc.).

The light (linearly polarized light) emitted from the light source 1 is collimated by the collimator lens 3 and then split into the first measurement light (reference light) and the second measurement light by the beam splitter 5. Then, the first measurement light (second division light) is reflected by the triangular prism 7, and the second measurement light (first division light) is reflected by the triangular prism 9, and after being folded back, the beam splitter 5 Synthesized by. Then, the synthesized light is reflected by the polarization beam splitter 11, converted into circularly polarized light by the 1/4 wave plate 13, and then irradiated to at least the optometry lens and the fundus of the eye through the dichroic mirror 15 and the examination window 17. To. At this time, when the measured luminous flux is reflected by the cornea and fundus of the subject's eye, the phase is converted by 1/2 wavelength.

The corneal reflected light and the fundus reflected light are converted into linear polarization by the 1/4 wave plate 13 via the inspection window 17 and the dichroic mirror 15. After that, the reflected light transmitted through the polarizing beam splitter 11 is focused by the condenser lens 19 and then received by the light receiving element 21.

In the above description, the optical path length changing member may be arranged in any of the measurement optical paths divided by the optical path dividing member, and may be moved so as to adjust the optical path difference between the divided measurement optical paths. Specifically, the optical path length changing member and the optical path dividing member are arranged in the optical path of the irradiation optical system 10 as shown in FIG. 1, the optical path of the light receiving optical system 20, or the irradiation optical system 10 and the light receiving optical system 20. It may be configured so as to be arranged in the common optical path of.

<Anterior segment imaging optical system>
An anterior segment imaging optical system 30 is provided in the reflection direction of the dichroic mirror 15. The anterior segment imaging optical system 30 is arranged to image the anterior segment of the eye to be inspected. The imaging optical system 30 has a dichroic mirror 15, an objective lens 31, a total reflection mirror 33, and an imaging lens 35 having a characteristic of transmitting the light emitted from the light source 1 and reflecting the light emitted from the anterior segment illumination light source 40. , A two-dimensional image pickup element 37. Here, the anterior segment image illuminated infraredly by the illumination light source 40 is imaged on the two-dimensional image pickup element 37 via the inspection window 17, the dichroic mirror 15, the objective lens 31, the reflection mirror 33, and the imaging lens 35. Will be done.
<Optometry optical system>
The fixation optical system 50 guides the line-of-sight direction of the eye E to be inspected. FIG. 2 is a diagram for explaining an optometry optical system. The fixation optical system 50 has an fixation light source 51 presented to the eye E to be examined, and can guide the eye E to be examined in a plurality of directions. For example, the fixation light source 51 emits visible light. The fixation light from the fixation light source 51 passes through the beam splitter 5 and is reflected by the triangular prism 9. Then, the fixation light again passes through the beam splitter 5, is reflected by the polarizing beam splitter 11, passes through the 1/4 wave plate 13, the dichroic mirror 15, and the inspection window 17, and is projected onto the eye to be inspected.

For example, the optometry optical system 50 includes a configuration in which the presentation position of the optotype is two-dimensionally changed. As a result, the line-of-sight direction is changed, and as a result, the measurement optical axis L1 with respect to the visual axis of the eye to be inspected is changed. For example, as shown in FIG. 2A, when the fixation target is presented from the same direction as the measurement optical axis L1, the central portion of the fundus is set as the measurement site. Further, as shown in FIG. 2B, when the fixation target is presented from the right side of the measurement optical axis L1 when viewed from the subject, the subject fixes the right side on which the fixation target is presented. Therefore, the right part of the fundus is set as the measurement site. That is, the measurement site is changed according to the position of the optotype with respect to the measurement optical axis L1. Similarly, as shown in FIG. 2C, when the fixation target is presented from the left side of the measurement optical axis L1 when viewed from the subject, the subject fixes the left side where the fixation target is presented. Therefore, the left part of the fundus is set as the measurement site.

The optometry optical system 50 of this embodiment includes, for example, a drive unit 52 for moving the optometry light source 51 (see FIG. 2). The control unit 52 drives the drive unit 52 to move the fixation light source 51, thereby changing the fixation position. The fixation optical system 50 includes, for example, a configuration in which the fixation position is adjusted according to the lighting positions of LEDs arranged in a matrix, a configuration in which light from a light source is scanned by an optical scanner, and lighting control of a light source such as an LCD. Various configurations such as a configuration for adjusting the fixation position can be considered. Further, the optometry optical system 50 may be an internal optometry lamp type or an external optometry lamp type. The fixation light source 51 may be a light source having a color different from that of the measurement light. As a result, it is possible to reduce the fact that the light of the fixation lamp is mixed with the measurement light.

<Control system>
Next, the control system of the apparatus according to this embodiment will be described. The control unit 80 includes a CPU (processor), RAM, ROM, and the like. The CPU of the control unit 80 controls the entire device. The RAM temporarily stores various types of information. The ROM of the control unit 80 stores various programs, initial values, and the like for controlling the operation of the entire device. The control unit 80 may be composed of a plurality of control units (that is, a plurality of processors).

A non-volatile memory (storage means) 85, an operation unit (control unit) 84, a display unit (monitor) 82, and the like are electrically connected to the control unit 80. The non-volatile memory (memory) 85 is a non-transient storage medium capable of retaining the storage contents even when the power supply is cut off. For example, a hard disk drive, a flash ROM, a detachably attached USB memory, or the like can be used as the non-volatile memory 85. The memory 85 contains a control program for controlling the acquisition of the interference signal by the interference optical system, a control program for acquiring the axial length from the acquired interference signal, and eyeball shape information of the eye to be inspected from a plurality of axial lengths. The control program and the like for acquiring the above are stored. In addition, various information related to measurement such as an interference signal, an axial length, and information on a measurement position of the axial length are stored in the memory 85. Various operation instructions by the inspector are input to the operation unit 84.

The operation unit 84 outputs a signal corresponding to the input operation instruction to the control unit 80. For the operation unit 84, for example, at least one of a mouse, a joystick, a keyboard, a touch panel, and the like may be used.

The monitor 82 may be a display mounted on the main body of the apparatus or a display connected to the main body. A display of a personal computer (hereinafter referred to as "PC") may be used. A plurality of displays may be used together. Further, the monitor 82 may be a touch panel. When the monitor 82 is a touch panel, the monitor 82 functions as an operation unit. Various information such as an interference signal, an axial length, and measurement information acquired by the interference optical system may be displayed on the monitor 82.

The control unit 84 is provided with various switches such as a measurement start switch 84a that emits a measurement start trigger signal.

<Control operation>
The device described above can execute, for example, a first measurement mode for measuring the axial length of the eye to be inspected and a second measurement mode for acquiring eyeball shape information of the eye to be inspected. Hereinafter, a case where the eyeball shape information of the eye to be inspected is acquired in the second measurement mode will be described with reference to the flowchart of FIG.

First, the examiner supports the face of the subject by a face support unit (not shown) and operates the measurement start switch 84a. When the measurement start switch 84a is operated, the control unit 80 projects the optometry target onto the subject by the optometry optical system 50 and guides the optometry. For example, the control unit 80 turns on the fixation light source 51 and irradiates the eye E to be inspected with the fixation target from the direction on the measurement optical axis L1 (see FIG. 2). Subsequently, the control unit 80 starts the alignment of the measurement unit. While detecting the alignment state of the eye to be inspected, the control unit 80 moves the measurement unit in the up / down / left / right and front / back directions with respect to the eye to be inspected E, and places the measurement unit in a predetermined positional relationship with respect to the eye to be inspected E.

When the alignment is completed, the trigger signal for starting measurement is automatically or manually output, and the measurement light source 1 is turned on by the control unit 80. Then, the measurement light is irradiated to the eye to be inspected by the irradiation optical system 10, and the reflected light from the eye to be inspected by the measurement light is incident on the light receiving element 21 of the light receiving optical system 20.

Further, the control unit 80 controls the drive of the drive unit 71 to reciprocate the first triangular prism 7. Then, the control unit 80 calculates the axial length based on the timing at which the interference light is detected by the light receiving element 21.

In the case of reciprocating movement, the control unit 80 acquires the first interference signal output from the light receiving element 21 when the first triangular prism 7 is moved in the first direction (A direction), and also obtains the first interference signal. When the first triangular prism 7 is moved in the second direction (B direction) opposite to the direction, the second interference signal output from the light receiving element 21 is acquired, and the first interference signal and the second interference signal are obtained. The axial length of the eye to be examined is measured based on each interference signal of the interference signal.

As described above, the moving position of the prism 7 when the interference signal is output from the light receiving element 21 differs depending on the axial length of the eye to be inspected. Then, the moving position of the prism 7 when the interference signal is output can be detected based on the signal output from the position detection sensor 72. Therefore, the axial length value can be calculated by, for example, obtaining the relationship between the moving position of the prism 7 and the axial length of the eye to be inspected in advance using a predetermined calculation formula or a table or the like.

The acquired information on the axial length of the eye to be inspected is stored in the memory 85. Further, when the measurement of a predetermined number of times is completed (or when a predetermined number of axial length values of the subject are obtained), the control unit 80 ends the reciprocating movement of the prism 7 and sets the moving position of the prism 7 to the initial position. Restore.

<Change of measurement position>
When the first measurement is completed, the control unit 80 changes the fixation position of the eye to be inspected. For example, the control unit 80 controls the position of the fixation light source 51 by the drive unit 52, and changes the fixation position of the eye E to be inspected. For example, as shown in FIG. 2, in the first measurement, the fixation light source 51 is arranged at the fixation position M1, and in the second measurement, the fixation is located on the left side in the horizontal direction from the fixation position M1 with respect to the eye to be inspected. The optometry light source 51 is moved to the position M2. The visual axis L9 of the eye to be inspected switches from the direction of the optical axis L1 to the direction of the optical axis L2 by switching the position of the fixation light source 51 from the fixation position M1 to the fixation position M2. In this way, the control unit 80 changes the fixation position of the subject by switching the lighting position of the fixation light source 51, and tilts the observation axis L9 of the eye to be inspected with respect to the measurement optical axis L1. The control unit 80 measures the axial length by irradiating the measurement light from a direction inclined with respect to the visual axis L9 of the subject. Therefore, as shown in FIG. 2, the axial length in the oblique direction with respect to the visual axis L9 is measured. In this embodiment, for example, the axial length of the eye to be inspected is measured from a direction inclined by ± θ ° with respect to the visual axis. Therefore, for example, the control unit 80 drives the drive unit 52, and the fixation position M1 for irradiating the fixation target from the direction of the measurement optical axis L1 and θ ° to the left side in the horizontal direction with respect to the measurement optical axis L1. The fixation position M2 for projecting the fixation target from an inclined direction and the fixation position M3 for projecting the fixation target from a direction inclined by −θ ° to the right side in the horizontal direction with respect to the measurement optical axis L1. The fixation light source 51 may be moved.

The direction in which the fixation light source 51 is moved does not have to be the horizontal direction. For example, the fixation light source 51 may be moved in the vertical direction or diagonally. Further, the fixation light source 51 does not have to be moved linearly, and may be moved curvedly.

In the above example, the fixation light source 51 is moved to a fixation position tilted by θ ° to the left and right with respect to the visual axis L9, but the fixation light source 51 is symmetrical to the left and right (or up and down) with respect to the visual axis. It is not necessary to move the fixed vision light source 51 asymmetrically left and right (or up and down).

The control unit 80, for example, switches the fixation position of the fixation light source 51 to measure the axial length of the eye E to be inspected, and stores the result in the memory 85. The control unit 80 measures the axial length of the eye E to be inspected at at least two different fixation positions. In this embodiment, the case where the fixation position is switched and the measurement is performed three times each will be described, but the fixation position may be switched two or more times to perform the measurement.

<Classification of eyeball deformation>
The control unit 80 determines the shape of the eyeball based on, for example, the measurement result of the axial length stored in the memory 85. As an example of determining the eyeball shape, for example, a method of classifying into several types of eyeball shape can be considered.

For example, as shown in FIG. 4, deformation of the eyeball shape in pathological myopia and the like can be classified into four types other than normal eyes. For example, FIG. 4A shows a normal eye. FIG. 4B is a nasal protruding type in which the fundus of the eye protrudes to the nasal side with left-right asymmetry. FIG. 4C shows an ear-side protruding type that is asymmetrical and the fundus of the eye protrudes toward the ear. FIG. 4D shows a spindle type that is symmetrical and has a pointed fundus. FIG. 4 (e) is a barrel shape that is symmetrical and has a rounded fundus. The control unit 80 classifies the types of eyeball deformation as described above based on the axial length from a plurality of directions with respect to the eye to be inspected, for example.

For example, in the control unit 80, among the three axial lengths measured from different measurement positions, the axial length measured when the position of the fixation light source 51 is the fixation position M1 and the position of the fixation light source 51 are The eye deformities may be classified by comparing the lengths of the axial lengths measured in the case of the fixation position M2 or the fixation position M3. In the following example, different measurement positions will be described depending on the angle (hereinafter referred to as the angle of view) formed by the measurement optical axis L1 and the visual axis L9.

For example, the control unit 80 may measure the axial length from three directions of an angle of view of 0 °, an angle of view of θ °, and an angle of view of −θ ° as different measurement positions, and classify the shape of the eyeball. For example, the control unit 80 may first determine whether or not the eyeball is deformed based on the axial length measured when the angle of view is 0 °. For example, when the difference between the measured axial length and the axial length of a normal eye is larger than a predetermined value, it may be determined that the eye to be examined is pathologically deformed.

Further, the control unit 80 may compare the axial length at the angle of view θ ° and the axial length at the angle of view −θ °, and classify the eyeball shapes according to the magnitude of the difference. For example, in the case of the eye to be inspected for the left eye, if the axial length at the angle of view θ ° is larger than the axial length at the angle of view −θ °, it may be determined that the eyeball shape of the eye to be inspected is a nasal protrusion type. .. On the contrary, when the axial length at the angle of view θ ° is smaller than the axial length at the angle of view −θ °, it may be determined that the eyeball shape of the eye to be inspected is the ear-side protruding type.

When the difference between the axial length at the angle of view θ ° and the axial length at the angle of view −θ ° is small, the control unit 80 may determine that the eyeball shape is symmetrical. In this case, the control unit 80 compares the axial length at an angle of view of 0 ° with the axial length at an angle of view of θ ° or −θ °, and the eye to be inspected is spindle-shaped based on the magnitude of the difference. It may be determined whether it is a barrel type or a barrel type. For example, if the difference between the two is large, the control unit 80 determines that the eyeball shape of the eye to be inspected is spindle-shaped, and if the difference is small, the eyeball shape of the eye to be inspected is barrel-shaped. Good.

Of course, the control unit 80 stores the axial lengths taken at each angle of view of the normal eye in the memory 85, and classifies the eyeball deformation of the test eye by comparing the axial lengths of the test eyes of the normal eye. You may. For example, the control unit 80 creates a table that can classify the types of eyeball deformation based on the magnitude of the difference between the axial length of the normal eye measured at each angle of view and the axial length of the eye to be inspected. The type of eyeball deformation may be classified in advance in the memory 85 based on this correspondence. It is not always necessary to measure the axial length at an angle of view of 0 °, and only the axial length at an angle of view ± θ ° symmetrical to the visual axis may be measured. In this case, the control unit 80 compares the axial lengths at the angle of view ± θ °, determines that the eyeball shape of the eye to be inspected is asymmetrical when the difference is large, and is symmetrical when the difference is large. It may be determined that it is a type.

As described above, pathological eyeball deformation can be classified by measuring the axial length at a plurality of different measurement positions. Therefore, the examiner can confirm the medical condition, progress, etc. of severe myopia, and can further predict the medical condition in the future. Further, it is not necessary to perform a large-scale measurement using CT, MRI, or the like, and the measurement can be easily performed as a screening, which leads to early detection of severe myopia.

In the above description, the control unit 80 has been described as moving the fixation light source 51 in the horizontal direction, but the present invention is not limited to this. For example, the control unit 80 may move the fixation light source 51 in the vertical direction. Thereby, the vertical eyeball shape of the eye to be inspected may be classified. Further, the fixation light source 51 may be moved not only in the horizontal direction and the vertical direction but also in an oblique direction, for example.

<Approximation of fundus shape>
The control unit 80 may approximate the eyeball shape from at least a plurality of measurement results stored in the memory 85. For example, the control unit 80 may obtain an approximate curve (ellipse) of the eyeball shape from the measurement result of the axial length. As shown in FIG. 5A, for example, the start points of the line segments D1, D2, and D3 having the same length as the axial length measured at the angle of view 0 °, the angle of view θ °, and the angle of view −θ ° are defined. The start points P1, P2, P3, and the end points are the end points Q1, Q2, and Q3, respectively. Further, the midpoints of the line segments D1, D2, and D3 are set as the midpoints C1, C2, and C3, respectively. For example, the midpoint C1, the midpoint C2, and the midpoint C3 are the origins of the polar coordinate system, and the start points P1, P2, P3 and the end points Q1, Q2, and Q3 are represented by polar coordinates, respectively. Then, the shape of the fundus may be approximated by an ellipse by passing through the coordinates of the end points Q1, Q2, Q3 (or the start points P1, P2, P3) and obtaining an ellipse centered on the origin of polar coordinates by an ellipse equation. .. The control unit 80 may perform the above calculation and approximate the eyeball shape from the plurality of measured axial lengths.

The control unit 80 may classify the types of eyeball deformation based on the approximated elliptical shape. For example, the ratio of the minor axis A to the major axis B of the ellipse R1 may be obtained, and if the ratio is larger than a predetermined value, it may be classified as a normal eye, and if the ratio is smaller than a predetermined value, it may be classified as a pathological myopic eye. For example, the control unit 80 stores the correspondence between the experimentally obtained ratio of the minor axis A and the major axis B and the measured type of eyeball deformation in the memory 85, and approximates the fundus shape of the eye E to be inspected. The type of eyeball deformation may be classified based on the ratio of the minor axis A and the major axis B of the elliptical ellipse R1 and the correspondence relationship stored in the memory 85. The control unit 80 may determine the left-right symmetry of the eye to be inspected based on the size of the inclination angle α of the ellipse.

<Display>
The control unit 80 may output the classification information of the eyeball deformation calculated as described above. For example, the names of the types of eyeball deformation classified as described above may be displayed on the display unit 82 (see FIG. 6). Further, the approximated ellipse R1 may be displayed on the display unit 82, or the graphic image of the eyeball calculated based on the approximated ellipse may be displayed on the display unit 82. Further, the control unit 80 may display the difference in the axial lengths measured at different measurement positions on the display unit 82. For example, the examiner can determine that the eye to be inspected has an abnormality such as pathological myopia when the displayed difference is large. The graphic image of the approximate ellipse R1 or the eyeball may be displayed on the display unit 82 so that the graphic image of the normal eye can be compared. Further, the display unit 82 may display the comparison result of comparing the data measured by the control eye with the data of the eye to be inspected. As a result, the examiner can visually confirm the degree of deformation of the eye to be inspected, and can easily diagnose the pathological myopia.

The control unit 80 may display the eyeball shape information in parallel with the display unit 82 in a state where the plurality of measurement positions and the axial lengths measured at the plurality of measurement positions correspond to each other. The examiner may diagnose the eyeball shape by confirming the measurement position of the axial length displayed on the display unit 82 and the axial length thereof.

The corneal shape may be used when analyzing the eyeball deformation. For example, the present apparatus may include a corneal shape measuring means for measuring the corneal shape. The corneal shape measuring means may be, for example, an optical interference tomography, a Shine pluque camera, a keratometer, a corneal topography, or the like.

For example, as described above, the midpoints C1, C2, and C3 of each axial length are overlapped, and the positions of the line segments D1, D2, and D3 are fixed so that the starting points P1, P2, and P3 match the corneal shape K. After adjusting under the above, ellipse approximation may be performed using the coordinates of the end points Q1, Q2, and Q3 (see FIG. 7). In this way, the approximation of the eyeball shape may be corrected based on the corneal shape of the eye to be inspected.

In the above description, the elliptical approximation of the eyeball shape is performed with the midpoint of the line segments D1, D2, and D3 having the same length as the axial length as the origin of the polar coordinate system, but the present invention is not limited to this. For example, as shown in FIG. 8, the positions separated from the start points P1, P2, and P3 by a predetermined distance are set as reference points U1, U2, and U3, respectively. Then, the control unit 80 may obtain an approximate curve using the coordinates of the end points Q1, Q2, and Q3 of the axial length when the reference points U1, U2, and U3 are overlapped with the origin of the polar coordinate system. Here, the predetermined distance from the start points P1, P2, P3 to the reference point may be, for example, an experimentally determined distance. For example, it may be the distance from the cornea to the center of rotation of the eye (for example, 13 mm). In this case as well, the approximation of the eyeball shape may be corrected based on the corneal shape as described above.

Further, for example, when the boundary between the cornea or the crystalline lens can be detected in the interference signal detected by the light receiving optical system 20, the eyeball shape of the eye to be inspected may be classified based on the positions of the cornea, the crystalline lens, and the like. For example, the control unit 80 may set the positions corresponding to the front surface of the crystalline lens in the line segments D1, D2, and D3 as reference points U1, U2, and U3, respectively. Then, the control unit 80 may obtain an approximate curve using the coordinates of the end points Q1, Q2, and Q3 when the reference points U1, U2, and U3 are overlapped with the origin of the polar coordinate system. The rear surface of the crystalline lens may be used as a reference, or the position between the front surface and the rear surface of the crystalline lens may be used as a reference.

Further, when the curved surface shape of the cornea or the crystalline lens can be measured by a tomographic image photographing means such as an optical interference tomography or a Shine Prouk camera, for example, the midpoint of the line segment passing through the two intersections of the front curve and the posterior curve of the lens is described above. The reference points U1, U2, and U3 may be set as such. Then, the reference points U1, U2, and U3 may be superimposed on the origin of the polar coordinate system, and the approximate curve may be obtained using the coordinates of the end points Q1, Q2, and Q3 at that time.

As described above, when the eyeball shape is approximated with a reference point other than the midpoint of the axial length, if the eyeball shape of the eye to be inspected is asymmetrical, the center of the acquired ellipse shifts with respect to the visual axis. .. Therefore, the control unit may determine the left-right symmetry of the eye to be inspected based on the amount of deviation between the visual axis and the center of the ellipse, and classify the types of eyeball deformation.

Information based on the eyeball shape information and the fundus information may be output. For example, as the fundus information, layer information of the fundus can be used. For example, when the thickness of the choroid can be measured by an interference optical system or another device, there is a configuration in which the classification information of the eyeball deformation and the choroid thickness are displayed together. Diagnosis can be made more effectively by confirming the thickness information of the choroid thinned by the deformation of the eyeball.

Further, in the above description, the configuration is such that the corneal reflected light and the fundus reflected light interfere with each other, but the present invention is not limited to this. That is, a beam splitter (light dividing member) that divides the light emitted from the light source, a sample arm that forms an object optical path, a reference arm that forms a reference optical path, and a light receiving element for receiving interference light. An interference optical system that uses a light receiving element to receive interference light from the measurement light (first division light) irradiated to the fundus of the eye to be examined via the sample arm and the reference light (second division light) from the reference arm. The present invention can be applied even to the provided axial length measuring device. In this case, the optical path length changing member is arranged at at least one of the sample arm and the reference arm.

<Second Example>
The device may be a Fourier domain type OCT device 101 that captures an optical tomography image of the eye to be inspected (see FIG. 9). For example, the OCT apparatus 101 may include an OCT optical system 200. The OCT optical system 200 divides the luminous flux emitted from the measurement light source 127 into the measurement light and the reference light. Further, the OCT optical system 200 guides the divided measurement luminous flux to the fundus Er of the eye to be inspected, and guides the reference light to the reference optical system 200b. After that, the detector (light receiving element) 183 detects the interference signal of the light in which the measurement reflected or backscattered by the fundus Er and the reference light are combined.

The OCT optical system 200 includes, for example, a fiber coupler 126, a measurement light source 127, optical fibers 138a, 138b, 138c, 138d, a measurement optical system 200a, a reference optical system 200b, and a spectroscopic optical system 800.

[OCT light source]
The measurement light source 127 is a light source that emits low-coherent light used as the measurement light and the reference light of the OCT optical system 200, and for example, an SLD light source or the like is used. As the measurement light source 127, for example, a light source having a central wavelength of 840 nm and a band of 50 nm is used.

[fiber]
The optical fibers 138a, 138b, 138c, and 138d allow light to pass through the inside and connect the measurement light source 127, the coupler 126, the measurement optical system 200a, the reference optical system 200b, the spectroscopic optical system 800, and the like.

[Fiber coupler]
The fiber coupler 126 also serves as an optical dividing member and an optical coupling member. The light emitted from the measurement light source 127 is divided into reference light and measurement light by the fiber coupler 126 via an optical fiber 138a as a light guide path. The measurement light is directed to the eye E to be inspected via the optical fiber 138b, and the reference light is directed to the reference mirror 131 via the optical fiber 138c (polarizer (polarizing element) 133).

[Measurement optical system]
The measurement optical system 200a, for example, guides the measurement light to the fundus Er. In the measurement optical system 200a, a collimator lens 121, a focusing optical member (focusing lens) 124, a scanning optical system (optical scanner) 123, a relay lens 122, and the like are arranged. The scanning optical system 123 is composed of, for example, two galvanometer mirrors, and is used to scan the measurement light emitted from the measurement light source 127 two-dimensionally (XY directions) on the fundus by driving the scanning drive mechanism 151. Be done. The scanning optical system 123 may be composed of, for example, an AOM (acousto-optic optical element), a resonant scanner, or the like.

The focusing lens 124 is movable in the optical axis direction by being driven by the driving unit 124a, and is used to correct the diopter of the subject's fundus Er.

The focusing lens 124 is moved in the optical axis direction by the drive of the drive unit 124a, and the movable range thereof is set. The focusing lens 124 can move, for example, in a range from a position where the refractive power corresponds to -14D (a position where the focus is achieved by the refractive power of -14D) to a position where the refractive power corresponds to + 14D.

The measurement light emitted from the end portion 139b of the optical fiber 138b is collimated by the collimator lens 121. After that, the measurement light reaches the scanning optical system 123 via the focusing lens 124, and the reflection direction is changed by driving the two galvanometer mirrors. Then, the measurement light reflected by the scanning optical system 123 is reflected by the dichroic mirror 140 described later via the relay lens 122, and then focused on the fundus of the eye to be inspected via the light guide optical system 110.

Then, the measurement light reflected by the fundus Er is reflected by the dichroic mirror 140 via the light guide optical system 110 and heads toward the OCT optical system 200. After that, the measurement light reflected by the fundus Er is incident on the end portion 139b of the optical fiber 138b via the relay lens 122, the two galvanometer mirrors of the scanning optical system 123, the focusing lens 124, and the collimator lens 121. The measurement light incident on the end portion 139b reaches the end portion 184a of the optical fiber 138d via the optical fiber 138b, the fiber coupler 126, and the optical fiber 138d.

[Reference optical system]
The reference optical system 200b produces reference light. The reference light is light that is combined with the reflected light of the measurement light reflected by the fundus Er. The reference optical system 200b may be a Michelson type or a Machzenda type. The reference optical system 200b is formed by, for example, a reflective optical system (for example, a reference mirror 131), and the light from the coupler 126 is reflected by the reflective optical system to be returned to the coupler 126 and guided to the detector 183. As another example, the reference optical system 200b is formed by a transmission optical system (for example, an optical fiber) and guides the light from the coupler 126 to the detector 183 by transmitting it without returning it.

For example, an optical fiber 138c, an end portion 139c of the optical fiber 138c that emits reference light, a collimator lens 129, and a reference mirror 131 are arranged in an optical path that emits reference light toward the reference mirror 131. The optical fiber 138c is rotationally moved by the drive mechanism 134 in order to change the polarization direction of the reference light. That is, the optical fiber 138c and the drive mechanism 134 are used as a polarizer 133 for adjusting the polarization direction. The polarizer is not limited to the above configuration, and may be any one that substantially matches the polarization states of the measurement light and the reference light by driving the polarizer arranged in the optical path of the measurement light or the optical path of the reference light. .. For example, a 1/2 wave plate or a 1/4 wave plate, or one that changes the polarization state by applying pressure to the fiber to deform it can be applied.

The polarizer 133 (polarization controller) may have a configuration in which at least one of the polarization directions of the measurement light and the reference light is adjusted in order to match the polarization directions of the measurement light and the reference light. For example, the polarizer 133 may be configured to be arranged in the optical path of the measurement light.

Further, the reference mirror driving unit 150 drives the reference mirror 131 and adjusts the optical path length of the reference light.

The reference light emitted from the end portion 139c of the optical fiber 138c is converted into a parallel luminous flux by the collimator lens 129 and reflected by the reference mirror 131. After that, the reference light is collected by the collimator lens 129 and incident on the end portion 139c of the optical fiber 138c. The reference light incident on the end 139c reaches the fiber coupler 126 via the optical fiber 138c and the optical fiber 138c (polarizer 133), and is guided to the spectroscopic optical system 800 via the fiber 138d.

[Spectroscopic optical system]
The spectroscopic optical system 800, for example, disperses the interference light of the reference light and the measurement light for each frequency (wavelength), and causes the detector 183 (one-dimensional light receiving element in this embodiment) to receive the dispersed interference light. ..

Then, the reference light generated as described above by the light emitted from the measurement light source 127 and the fundus reflected light which is the measurement light irradiated to the fundus Er of the eye to be inspected are combined by the fiber coupler 126 to be regarded as interference light. To. After that, the interference light is emitted from the end portion 184a through the optical fiber 138d. The spectroscopic optical system 800 (spectrometer unit) disperses the interference light into frequency components in order to obtain an interference signal for each frequency. The spectroscopic optical system 800 (spectrometer unit) includes, for example, a collimator lens 180, a grating mirror (diffraction grating) 181 and a condenser lens 182, and a detector 183. The detector 83 uses a one-dimensional element (line sensor) having sensitivity in the infrared region.

Here, the interference light emitted from the end portion 184a is converted into parallel light by the collimator lens 180, and then separated into frequency components by the grating mirror 181. Then, the interference light dispersed in the frequency component is condensed on the light receiving surface of the detector 183 via the condenser lens 182. As a result, the spectral information (spectral signal) of the interference fringes is recorded on the detector 83. Then, the tomographic image of the eye (fundus tomographic image) is imaged by analyzing using the Fourier transform based on the output signal from the detector 183. That is, the spectral information is input to the control unit 170 and analyzed by using the Fourier transform, so that the information in the depth direction of the eye to be inspected can be measured.

Here, the control unit 170 can acquire a tomographic image by scanning the measurement light on the fundus in a predetermined transverse direction by the scanning optical system 123. For example, by scanning in the X direction or the Y direction, a tomographic image (fundus tomographic image) on the XZ plane or the YZ plane of the fundus to be inspected can be obtained (in the present embodiment, the measurement light is used as the fundus. On the other hand, the method of obtaining a tomographic image by one-dimensional scanning is called B scanning). The acquired fundus tomographic image is stored in the memory 172 connected to the control unit 170. Further, by controlling the driving of the scanning optical system 123 and scanning the measurement light two-dimensionally in the XY direction, a two-dimensional moving image regarding the XY direction of the optometry eye base of the subject based on the output signal from the detector 183 is obtained. And can acquire a three-dimensional image of the fundus of the eye to be inspected.

[Focus target projection unit]
Next, the fixation target projection unit 300 will be described. The fixation target projection unit 300 has an optical system for guiding the line-of-sight direction of the eye E. The fixation target projection unit 300 has an fixation target presented to the eye E, and can guide the eye E in a plurality of directions. The fixation target projection unit 300 may have the same configuration as that of the first embodiment.

The fixation target projection unit 300 has, for example, a configuration in which the fixation position is adjusted according to the lighting positions of LEDs arranged in a matrix, the light from the light source is scanned by an optical scanner, and the fixation position is determined by lighting control of the light source. Various configurations such as an adjustment configuration can be considered. Further, the projection unit 300 may be an internal fixation light type or an external fixation light type.

[Dichroic mirror]
The OCT device 101 of this embodiment includes, for example, a dichroic mirror 140. For example, the dichroic mirror 140 has a property of reflecting the light of the wavelength component used as the measurement light of the OCT optical system 200 and transmitting the light of the wavelength component used in the fixation target projection unit 300.

<Control system>
Further, the control unit 170 is connected to a display monitor 175, a memory 172, an operation unit 174, a reference mirror drive unit 150, a focusing lens drive unit 124a, a drive mechanism 134 of an optical fiber 138c, a focal length variable 112 described later, and the like. There is.

<Light guide optical system>
The light guide optical system 110 is provided to guide the measurement light to the eye E to be inspected. The light guide optical system 110 includes, for example, an objective lens unit 111, a light collection position variable system 112, and the like.

[Variable focusing position]
The light-collecting position variable system 112 changes, for example, the light-collecting position of the measurement light passing through the light guide optical system 110. The light collection position variable system 112 may include, for example, an insertion / removal mechanism of an optical element. Then, the light collecting position variable system 112 may change the light collecting position of the measurement light passing through the light guide optical system 110 by inserting and removing the optical element with respect to the optical axis of the light guide optical system 110. As the light collection position variable system 112, for example, a refractive power variable system 113 capable of changing the refractive power may be used. The variable refractive power system 113 may change the condensing position of the measurement light, for example, by changing the refractive power.

In this embodiment, the case where the variable refractive power system 113 is used as the variable light collection position system 112 will be described. The variable refractive power system 113 switches the condensing position of the measurement light between the fundus portion Er and the anterior segment portion Ec, for example, by changing the refractive power. The refractive power variable system 113 may continuously change the refractive power.

The variable refractive power system 113 is arranged, for example, behind the objective lens unit 111 with respect to the eye E to be inspected. In this embodiment, the variable refractive power system 113 is arranged between the objective lens unit 111 and the dichroic mirror 140. However, the variable refractive power system 113 may be arranged on the side to be inspected with respect to the objective lens unit 111, or may be arranged in the middle of the objective lens unit 111.

FIG. 10A shows a state when the refractive power of the variable refractive power system 113 is controlled so that the measurement light is focused on the fundus Er. When the measurement light is focused on the fundus Er, the control unit 170 controls the variable refractive power system 113, and the refractive power is variable so that the measurement light irradiated to the eye to be inspected by the light guide optical system 110 becomes a parallel light beam. The refractive power of the system 113 is changed. If the eye to be inspected is an emmetropic eye, the measurement light is focused on the fundus Er by the refractive power of the cornea and the crystalline lens. If the eye to be inspected is not an emmetropic eye, the refractive power of the variable refractive power system 113 may be adjusted according to the refractive power of the eye to be inspected E.

FIG. 10B shows a state when the measurement light is focused on the anterior segment Ec by controlling the refractive power of the variable refractive power system 113. When the measurement light is focused on the anterior segment Ec, the control unit 170 controls the refractive power variable system 113, and the measurement light irradiated to the subject E by the light guide optical system 110 is the anterior segment Ec of the subject E. The refractive power of the variable refractive power system 113 is changed so as to concentrate on.

In this way, the variable refractive power system 113 can change the refractive power by being electrically driven by the control unit 170 without moving the variable refractive power system 113 itself with respect to the optical axis L11. .. Therefore, the variable refractive power system 113 may be three-dimensionally fixed with respect to the optical axis L11.

The variable refractive power system 113 of this embodiment may include, for example, a liquid crystal lens or the like. The liquid crystal lens is, for example, a lens having a structure in which the refractive power is continuously changed by controlling the applied voltage.

<Fundus anterior eye switching method>
In the ophthalmologic apparatus (OCT device 1) having the above configuration, switching between imaging of the fundus Er and imaging of the anterior segment Ec will be described.

First, when photographing the fundus portion Er, the control unit 170 adjusts the refractive power variable system 113 to a predetermined refractive power so that the measurement light emitted from the light guide optical system 110 becomes a parallel light flux. Further, the control unit 170 controls the reference mirror drive unit 150 to move the reference mirror 131 and adjust the optical path length. For example, the control unit 170 moves the reference mirror 131 to a predetermined first position set in advance. As a result, the optical path lengths of the reference light reflected by the reference mirror 131 and the measurement light reflected by the fundus Er are equal, and when the reference light and the measurement light are combined by the fiber coupler 126, an interference signal is generated. Will be done. The detector 183 acquires this interference signal and sends it to an image generation means (for example, control unit 170). When the image generation means receives the interference signal, it acquires the fundus tomographic image W1 (see FIG. 11).

Subsequently, when switching to imaging of the anterior segment Ec, the control unit 170 controls the refractive power variable system 113 to adjust the refractive power so that the measurement light is focused on the anterior segment Ec. For example, as described above, the refractive power of the variable refractive power system 113 is increased, and the measurement light is switched so as to be focused on the anterior segment Ec. Further, the control unit 170 controls the reference mirror drive unit 150 to move the reference mirror 131 and adjust the optical path length. For example, the control unit 170 moves the reference mirror 131 to a predetermined second position set in advance. As a result, the optical path lengths of the reference light reflected by the reference mirror 131 and the measurement light reflected by the anterior segment Ec become equal, and when the reference light and the measurement light are combined by the fiber coupler 126, an interference signal is generated. Generate. The detector 183 acquires this interference signal and sends it to the image generation means. Upon receiving the interference signal, the image generation means generates an anterior segment tomographic image W2 (see FIG. 11).

As described above, by switching the reference mirror 131 when switching the condensing position of the measurement light, it is possible to acquire tomographic images of both the fundus Er and the anterior eye Ec. The control unit 170 may measure the axial length of the eye to be inspected using tomographic images of the anterior eye portion Ec and the fundus portion Er. At this time, since the positional relationship between the fundus tomographic image W1 and the anterior ocular tomographic image W2 may be reversed, the control unit 170 inverts one of the images and then obtains the axial length by image processing. You may.

Further, the control unit 170 may classify the eyeball shape using the axial lengths measured from at least three different angles of view. For example, the control unit 170 may scan the measurement light from the measurement light source 127 by the scanning optical system 123 on the fundus of the eye with the pupil or the like as a fulcrum, and measure the axial length from different angles of view. Similar to the first embodiment, the control unit 170 may classify the types of eyeball deformation of the eye to be inspected based on the axial lengths measured from different angles of view.

When the control unit 170 irradiates the eye to be inspected with the measurement light from the measurement light source 127 as a parallel luminous flux, for example, as shown in FIG. 10B, the fixation of the eye to be inspected by the fixation guidance unit 300, for example. May be guided and the visual axis may be tilted with respect to the measurement optical axis L11. Thereby, the control unit 170 may acquire the axial length measured from different angles of view and classify the type of eyeball deformation of the eye to be inspected.

Of course, the axial length at different angles of view may be measured by scanning the measurement light on the anterior eye portion and the fundus portion by the scanning optical system 123, and the types of eyeball deformation may be classified.

The method of OCT may be spectral domain OCT or swept source OCT.

In the above description, the case where the refractive power is changed by using a variable refractive power element (for example, a liquid crystal lens, a liquid lens, etc.) or the like has been described, but the refractive power may be changed by driving an optical member such as a lens. Good. Further, although the position of the reference mirror 131 is switched, a plurality of reference mirrors having different optical paths may be provided in the reference optical system.

In the above configuration, tomographic images of the anterior segment and the fundus are taken separately, but the present invention is not limited to this. For example, the present device may be configured to capture tomographic images of the anterior segment and the fundus at the same time. For example, the interference optical system may have a configuration having a measurement range capable of photographing the anterior segment and the fundus at the same time. For example, a measurement light source capable of photographing the anterior segment and the fundus at the same time may be provided. In this case, the control unit 170 may acquire the axial length of the eye to be inspected by performing image processing on an image including the anterior eye portion and the fundus portion.

When the fundus tomographic image of the eye to be inspected is acquired as described above, for example, the control unit 170 detects the position of the macula or the optic nerve head by image processing or the like, so that the fixation of the eye to be inspected is correct. You may determine if it is done. Then, based on this determination result, the control unit 170 may change the geodetic position of the axial length by controlling the fixation position or scanning the measurement light. In this way, by stabilizing the measurement position of the eye to be inspected, it may be easy to follow up the shape of the eyeball of the eye to be inspected.

Claims (5)

The eye to be inspected is provided with an interference optical system for detecting an interference signal between the measurement light irradiated to the eye to be inspected and the reference light, and the interference optical system receives the reflected light from the corneal membrane and the reflected light from the fundus of the eye by the interference optical system. It is an axial length measuring device that measures the axial length, which is the distance from the optometry to the fundus of the eye.
A measurement position changing means for changing the measurement position of the axial length on the eye to be examined to a plurality of measurement positions including the ear side and the nasal side of the fundus with the pupil of the eye to be inspected as a fulcrum.
An acquisition means for acquiring the axial length based on an interference signal from the interference optical system, and
With
The acquisition means acquires the axial length at a plurality of measurement positions including the ear side and the nasal side, which are changed by the measurement position changing means, and a plurality of measurement positions including the ear side and the nasal side. An axial length measuring device, characterized in that it acquires eyeball shape information of the eye to be inspected based on the axial length of the eye. Further provided with display control means for controlling the display of the display means,
The acquisition means acquires the type of eyeball shape of the eye to be inspected and the choroidal thickness determined based on the axial length at a plurality of measurement positions including the ear side and the nose side.
The axial length measuring device according to claim 1, wherein the display control means causes the display means to display the type of the eyeball shape and the choroidal film thickness. Further provided with display control means for controlling the display of the display means,
The axial length measuring device according to claim 1, wherein the display controlling means causes the display means to display difference information of the axial lengths compared at a plurality of measurement positions including the ear side and the nasal side. .. It is a method of acquiring eyeball shape information.
On the same eye to be inspected, the interference signal between the measurement light and the reference light applied to the inspected eye is detected at a plurality of measurement positions including the ear side and the nose side of the fundus with the pupil of the inspected eye as a fulcrum. An axial length acquisition step for acquiring the axial length, which is the distance from the corneum of the eye to be inspected to the fundus , measured by receiving the corneal reflected light and the fundus reflected light by the measurement light by the interference optical system .
A shape information acquisition step for acquiring eyeball shape information of the eye to be inspected based on the axial length acquired in the acquisition step, and a shape information acquisition step.
A method for acquiring eyeball shape information, which comprises. An eyeball shape information acquisition program executed in a control device that controls the operation of the eyeball shape information acquisition device.
By being executed by the processor of the control device,
On the same eye to be inspected, the interference signal between the measurement light and the reference light applied to the inspected eye is detected at a plurality of measurement positions including the ear side and the nose side of the fundus with the pupil of the inspected eye as a fulcrum. An axial length acquisition step for acquiring the axial length, which is the distance from the corneum of the eye to be inspected to the fundus , measured by receiving the corneal reflected light and the fundus reflected light by the measurement light by the interference optical system .
A shape information acquisition step for acquiring eyeball shape information of the eye to be examined based on the axial length acquired in the acquisition step,
The eyeball shape information acquisition program, characterized in that the eyeball shape information acquisition device is executed.

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