JP7528933B2 - Optical coherence tomography apparatus and optical module - Google Patents

Description

The technology disclosed herein relates to an optical coherence tomography imaging device and an optical module.

U.S. Patent Application Publication No. 2009/0149742 discloses an anterior segment optical coherence tomography device equipped with an automatic eye tracking means for moving the device body so as to maintain a constant positional relationship between the corneal apex and the device body while acquiring a tomographic image of the anterior segment of the subject eye.

There is a demand for an optical coherence tomography device that can perform eye tracking with a simpler configuration rather than a complex configuration that requires the device body to move in a tracking manner.

The optical coherence tomography apparatus according to a first aspect of the disclosed technique comprises a light source that generates light for optical coherence tomography, a light splitting means that splits the light from the light source into reference light and measurement light, a scanning means that scans the measurement light, an optical element that is arranged in the optical path of the measurement light and emits the measurement light scanned by the scanning means to the subject's eye, an optical element driving means that moves the optical element within a plane that intersects the optical axis of the optical element, a motion detection means that detects the movement of the subject's eye, a drive control means that controls the optical element driving means based on the movement information of the subject's eye detected by the motion detection means, an interference light detection means that detects interference light obtained by combining the return light from the subject's eye and the reference light, and an image generation means that forms a tomographic image of the subject's eye based on the detection signal detected by the interference light detection means.

An optical coherence tomography apparatus according to a second aspect of the disclosed technology is an optical coherence tomography apparatus that generates a tomographic image from interference light between measurement light and reference light that have passed through a test eye, and has a posterior eye observation mode that generates a tomographic image of the posterior eye segment of the test eye, and an anterior eye observation mode that generates a tomographic image of the anterior eye segment of the test eye, and is characterized in that it is equipped with a mode selection means that sets either the posterior eye observation mode or the anterior eye observation mode, and a tracking execution means that, when the mode selection means selects the posterior eye observation mode, executes a first eye tracking control that causes the irradiation position of the measurement light at the posterior eye segment to follow the movement of the test eye, and, when the mode selection means selects the anterior eye observation mode, executes a second eye tracking control that causes the irradiation position of the measurement light at the anterior eye segment to follow the movement of the test eye.

The optical module of the third aspect of the technology disclosed herein is an optical module that is detachable from an optical coherence tomography imaging device that acquires a tomographic image from interference light between measurement light and reference light that has passed through a test eye, and is characterized in that it comprises an optical element that is arranged in the optical path of the measurement light, and an optical element driving means that moves the optical element within a plane that intersects with the optical axis of the optical element.

1 is a schematic configuration diagram of an ophthalmic apparatus according to a first embodiment. 1 is a schematic diagram illustrating the configuration of a photographing optical system according to a first embodiment. 11 is a schematic diagram of a photographing optical system when an optical module for observing an anterior eye segment is not inserted in the optical path of an objective lens. FIG. 1 is a schematic diagram of a photographing optical system when an optical module for observing an anterior eye segment is inserted in the optical path of an objective lens. FIG. The upper figure is a schematic optical configuration diagram of the first lens group and the second lens group when an optical module for observing the anterior eye is not inserted in the optical path between the first lens group and the second lens group, and the lower figure is a schematic optical configuration diagram of the first lens group and the second lens group when a module for the anterior eye is inserted in the optical path between the first lens group and the second lens group. 13 is a flowchart of an optical coherence tomographic image generating process. FIG. 13 is a schematic diagram illustrating the configuration of a photographing optical system according to a second embodiment. FIG. 13 is a schematic diagram illustrating the configuration of a photographing optical system according to a third embodiment.

Below, embodiments of the technology disclosed herein are described in detail with reference to the drawings.

[First embodiment]

Below, the ophthalmic device 110 relating to the first embodiment of the technology disclosed herein is described with reference to the drawings.

Figure 1 shows a schematic configuration of an ophthalmic device 110.

For ease of explanation, Scanning Laser Ophthalmoscope is referred to as "SLO" and Optical Coherence Tomography is referred to as "OCT."

When the ophthalmic device 110 is placed on a horizontal plane, the horizontal direction is the "X direction", the vertical direction relative to the horizontal plane is the "Y direction", and the optical axis direction of the imaging optical system 116A is the "Z direction". Therefore, the X direction, Y direction, and Z direction are perpendicular to each other.

The ophthalmologic apparatus 110 includes an imaging device 14 and a control device 16. The imaging device 14 includes an SLO unit 18 for acquiring an image of the fundus 12A of the subject's eye 12, and an OCT unit 20 for acquiring a tomographic image of the subject's eye 12. Hereinafter, a fundus image generated based on SLO data acquired by the SLO unit 18 is referred to as an SLO image. Also, a tomographic image generated based on OCT data acquired by the OCT unit 20 is referred to as an OCT image. The SLO image may also be referred to as a two-dimensional fundus image. Also, the OCT image may also be referred to as a fundus tomographic image or an anterior segment tomographic image depending on the imaging site of the subject's eye 12.
The ophthalmic apparatus 110 is an example of an “optical coherence tomography apparatus” of the technology of the present disclosure.

The control device 16 comprises a computer having a central processing unit (CPU) 16A, a random access memory (RAM) 16B, a read-only memory (ROM) 16C, and an input/output (I/O) port 16D.
The CPU 16A is an example of the "drive control means" of the technology of the present disclosure.

The control device 16 is equipped with an input/display device 16E connected to the CPU 16A via an I/O port 16D. The input/display device 16E has a graphic user interface that displays an image of the subject's eye 12 and receives various instructions from the user. The input/display device 16E can be a touch panel display.

The control device 16 also includes an image processing device 17 connected to the I/O port 16D. The image processing device 17 generates an image of the subject's eye 12 based on the data obtained by the photographing device 14.
The image processing device 17 is an example of the "image generating means" of the technology of the present disclosure.

As described above, in FIG. 1, the control device 16 of the ophthalmic device 110 is provided with an input/display device 16E, but the technology of the present disclosure is not limited to this. For example, the control device 16 of the ophthalmic device 110 may not be provided with the input/display device 16E, but may be provided with a separate input/display device that is physically independent from the ophthalmic device 110. In this case, the display device includes an image processing processor unit that operates under the control of the CPU 16A of the control device 16. The image processing processor unit may display an SLO image, etc., based on an image signal that the CPU 16A instructs to output.

The imaging device 14 operates under the control of the control device 16. The imaging device 14 includes an SLO unit 18, an imaging optical system 116A, and an OCT unit 20. The imaging optical system 116A is moved in the X, Y, and Z directions by an imaging optical system drive unit 116M under the control of the CPU 16A. Alignment (positioning) between the imaging device 14 and the subject's eye 12 may be performed, for example, by moving the imaging device 14 or the ophthalmic device 110 in the X, Y, and Z directions.

The SLO system is realized by the control device 16, SLO unit 18, and imaging optical system 116A shown in Figure 1.

The SLO unit 18 has a plurality of light sources. For example, as shown in FIG. 1, the SLO unit 18 has a light source 40 of B light (blue light), a light source 42 of G light (green light), a light source 44 of R light (red light), and a light source 46 of IR light (infrared light (e.g., near-infrared light)). The light emitted from each light source 40, 42, 44, 46 is directed to the same optical path via each optical member 48, 50, 52, 54, 56. The optical members 48, 56 are mirrors, and the optical members 50, 52, 54 are beam splitters. The B light is guided to the optical path of the imaging optical system 116A via the optical members 48, 50, 54. The G light is guided to the optical path of the imaging optical system 116A via the optical members 50, 54. The R light is guided to the optical path of the imaging optical system 116A via the optical members 52, 54. The IR light is guided to the optical path of the photographing optical system 116A via the optical members 56 and 52. The light sources 40, 42, 44, and 46 may be LED light sources or laser light sources. An example using a laser light source will be described below. The optical members 48 and 56 may be total reflection mirrors. The optical members 50, 52, and 54 may be dichroic mirrors, half mirrors, etc.

The SLO unit 18 is configured to be switchable between various light emission modes, such as a light emission mode in which G light, R light, B light, and IR light are emitted individually, and a light emission mode in which all or some of these light emission modes are emitted simultaneously.
1, four light sources are provided: a B light (blue light) light source 40, a G light source 42, an R light source 44, and an IR light source 46; however, the technology of the present disclosure is not limited to this. For example, the SLO unit 18 may further include a white light source. In this case, in addition to the various light emission modes described above, a light emission mode that emits only white light may be set.

The laser light incident on the imaging optical system 116A from the SLO unit 18 is scanned in the X and Y directions by the scanning units (120, 142) described below. The scanning light passes through the pupil 27 and is irradiated onto the posterior segment (e.g., fundus 12A) of the subject's eye 12. The reflected light reflected by the fundus 12A is incident on the SLO unit 18 via the imaging optical system 116A.

The reflected light reflected by the fundus 12A is detected by the light detection elements 70, 72, 74, and 76 provided in the SLO unit 18. In this embodiment, the SLO unit 18 is provided with a B light detection element 70, a G light detection element 72, an R light detection element 74, and an IR light detection element 76 corresponding to a plurality of light sources, i.e., the B light source 40, the G light source 42, the R light source 44, and the IR light source 46. The B light detection element 70 detects the B light reflected by the beam splitter 64. The G light detection element 72 detects the G light that passes through the beam splitter 64 and is reflected by the beam splitter 58. The R light detection element 74 detects the R light that passes through the beam splitters 64 and 58 and is reflected by the beam splitter 60. The IR light detection element 76 detects the IR light that passes through the beam splitters 64, 58, and 60 and is reflected by the beam splitter 62. The light detection elements 70, 72, 74, and 76 may be, for example, an avalanche photodiode (APD).

Under the control of the CPU 16A, the image processing device 17 generates an SLO image corresponding to each color using signals detected by the B light detection element 70, the G light detection element 72, the R light detection element 74, and the IR light detection element 76. The SLO images corresponding to each color include a B-SLO image generated using a signal detected by the B light detection element 70, a G-SLO image generated using a signal detected by the G light detection element 72, an R-SLO image generated using a signal detected by the R light detection element 74, and an IR-SLO image generated using a signal detected by the IR light detection element 76. In addition, in the case of a light emission mode in which the B light source 40, the G light source 42, and the R light source 44 emit light simultaneously, an RGB-SLO image may be synthesized from the R-SLO image, the G-SLO image, and the B-SLO image generated using the signals detected by the R light detection element 74, the G light detection element 72, and the B light detection element 70, respectively. Furthermore, in the case of a light emission mode in which the G light source 42 and the R light source 44 emit light simultaneously, an RG-SLO image may be synthesized from an R-SLO image and a G-SLO image generated using the respective signals detected by the R light detection element 74 and the G light detection element 72. In the first embodiment, an RG-SLO image is used as the SLO image, but this is not limiting, and other SLO images may be used.
As the beam splitters 58, 60, 62, and 64, a dichroic mirror, a half mirror, or the like can be used.

The OCT system is a three-dimensional image acquisition device realized by the control device 16, the OCT unit 20, and the imaging optical system 116A shown in Figure 1. The OCT unit 20 includes a light source 20A, a sensor (detection element) 20B, a first optical coupler 20C, a reference optical system 20D, a collimating lens 20E, and a second optical coupler 20F.

The light source 20A generates light for optical coherence tomography. For example, a super luminescent diode (SLD) can be used as the light source 20A. The light source 20A generates low-coherence light of a broadband light source having a wide spectral width. The light emitted from the light source 20A is split by a first optical coupler 20C. One of the split lights is collimated by a collimating lens 20E as a measurement light, and then is incident on the imaging optical system 116A. The measurement light is scanned in the X direction and the Y direction by a scanning unit (148, 142) described later. The scanning light is irradiated to the anterior segment of the subject's eye and the posterior segment via the pupil 27. The measurement light reflected by the anterior or posterior eye segment is incident on the OCT unit 20 via the photographing optical system 116A, and then incident on the second optical coupler 20F via the collimator lens 20E and the first optical coupler 20C. Note that, although the present embodiment illustrates an SD-OCT using an SLD as the light source 20A, the present invention is not limited thereto, and an SS-OCT using a wavelength swept light source instead of an SLD may be adopted.
The first optical coupler 20C is an example of a "light splitting means" in the technology of the present disclosure. The scanning units (148, 142) are an example of a "scanning means" in the technology of the present disclosure.

The other light emitted from the light source 20A and split by the first optical coupler 20C is incident on the reference optical system 20D as reference light, and passes through the reference optical system 20D to be incident on the second optical coupler 20F.

The measurement light (return light) reflected and scattered by the subject's eye 12 and the reference light are combined by the second optical coupler 20F to generate interference light. The interference light is detected by the sensor 20B. The image processing device 17 generates a tomographic image based on the detection signal (OCT data) from the sensor 20B.
The sensor 20B is an example of the "interference light detection means" of the technology of the present disclosure.

In the first embodiment, the OCT system generates a tomographic image of the anterior or posterior segment of the test eye 12.

The anterior segment of the subject's eye 12 includes, as an anterior segment, the cornea, the iris, the angle, the crystalline lens, the ciliary body, and a part of the vitreous body. The posterior segment of the subject's eye 12 includes, as a posterior segment, the remaining part of the vitreous body, the retina, the choroid, and the sclera. The vitreous body belonging to the anterior segment is the part of the vitreous body on the cornea side with respect to the X-Y plane passing through the point of the crystalline lens closest to the center of the eyeball as a boundary, and the vitreous body belonging to the posterior segment is the part of the vitreous body other than the vitreous body belonging to the anterior segment.
When the anterior segment of the subject's eye 12 is the imaging target region, the OCT system generates, for example, a tomographic image of the cornea. When the posterior segment of the subject's eye 12 is the imaging target region, the OCT system generates, for example, a tomographic image of the retina.

2 shows a schematic configuration of the imaging optical system 116A. The imaging optical system 116A includes, in order from the subject's eye 12 side, an objective lens 130, a beam splitter 178, a horizontal scanning unit 142, a relay lens device 140, a beam splitter 147, vertical scanning units 120 and 148, a focus adjustment device 150, and a collimator lens 156.
As the beam splitters 178 and 147, for example, a dichroic mirror, a half mirror, or the like can be used.

The horizontal scanning unit 142 is an optical scanner that horizontally scans the SLO laser light and the OCT measurement light incident via the relay lens device 140. In this embodiment, the horizontal scanning unit 142 is shared by the SLO optical system and the OCT optical system, but this is not limited to this. A horizontal scanning unit may be provided for each of the SLO optical system and the OCT optical system.

The collimator lens 156 converts the measurement light emitted from the end 158 of the fiber through which the light emitted from the OCT unit 20 travels into parallel light.

The focus adjustment device 150 includes multiple lenses 152, 154. The focus position of the measurement light in the test eye 12 is adjusted by moving each of the multiple lenses 152, 154 appropriately in the optical axis direction according to the imaging area in the test eye 12. Although not shown, if a focus detection device is included, it is possible to realize an autofocus device by driving the lenses 152, 154 with the focus adjustment device according to the focus detection state to automatically adjust the focus.

The vertical scanning unit 148 is an optical scanner that scans the measurement light incident through the focus adjustment device 150 in the vertical direction.

The vertical scanning unit 120 is an optical scanner that scans the laser light incident from the SLO unit 18 in the vertical direction.

The relay lens device 140 includes multiple lenses 144, 146 having positive power. The multiple lenses 144, 146 configure the relay lens device 140 so that the positions of the vertical scanning units 120, 148 and the horizontal scanning unit 142 are conjugate. More specifically, the relay lens device 140 is configured so that the central positions of the angular scanning of both scanning units are conjugate.

The beam splitter 147 is disposed between the relay lens device 140 and the vertical scanning unit 148. The beam splitter 147 is an optical member that combines the SLO optical system and the OCT optical system, and reflects the SLO light emitted from the SLO unit 18 toward the relay lens device 140, and transmits the measurement light emitted from the OCT unit 20 toward the relay lens device 140. The measurement light emitted from the OCT unit 20 is two-dimensionally scanned by the vertical scanning unit 148 and the horizontal scanning unit 142. Furthermore, the light emitted from the SLO unit 18 is two-dimensionally scanned by the vertical scanning unit 120 and the horizontal scanning unit 142 that configure the SLO optical system.
In this embodiment, the scanning speed of the vertical scanning unit 120 is, for example, several times faster than the scanning speed of the vertical scanning unit 148. Therefore, while the measurement light emitted from the OCT unit 20 is vertically scanned once by the vertical scanning unit 148, the light emitted from the SLO unit 18 is vertically scanned several times by the vertical scanning unit 120.

The two-dimensionally scanned OCT measurement light and SLO laser light are each incident on the test eye 12 via the objective lens 130 constituting a common optical system. The SLO laser light reflected by the test eye 12 is incident on the SLO unit 18 via the objective lens 130, horizontal scanning unit 142, relay lens device 140, beam splitter 147, and vertical scanning unit 120. The OCT measurement light that has passed through the test eye 12 is incident on the OCT unit 20 via the objective lens 130, horizontal scanning unit 142, relay lens device 140, beam splitter 147, vertical scanning unit 148, focus adjustment device 150, and collimator lens 156.

As the horizontal scanning unit 142 and the vertical scanning units 120 and 148, for example, a resonant scanner, a galvanometer mirror, a polygon mirror, a rotating mirror, a dowel prism, a double dowel prism, a rotation prism, a MEMS mirror scanner, an acousto-optical element (AOM), etc. are preferably used. In this embodiment, a galvanometer mirror is used as the vertical scanning unit 148, and a polygon mirror is used as the vertical scanning unit 120. Note that when a two-dimensional optical scanner such as a MEMS mirror scanner is used instead of an optical scanner such as a polygon mirror or a galvanometer mirror, the incident light can be two-dimensionally angle scanned by the reflecting element, so the relay lens device 140 may be eliminated.

The objective lens 130 includes, in order from the horizontal scanning unit 142 side, a first lens group 134 and a second lens group 132, and at least the second lens group 132 is a positive lens group having a positive power overall. In the first embodiment, the first lens group 134 is also a positive lens group having a positive power overall. Each of the first lens group 134 and the second lens group 132 includes at least one positive lens. When each of the first lens group 134 and the second lens group 132 includes multiple lenses, each of the first lens group 134 and the second lens group 132 may include a negative lens as long as it has a positive power overall.

The first lens group 134 and the second lens group 132 constituting the objective lens 130 are separated by the maximum air gap on the optical axis between the lens surfaces of the objective lens. Even if there is a glass plate having no power between the first lens group 134 and the second lens group 132, the glass plate is not considered to be a lens belonging to either the first lens group 134 or the second lens group 132, and the first lens group 134 and the second lens group 132 are considered to be separated by the maximum air gap.

The photographing optical system 116A includes an optical module 136 for observing the anterior eye as an optical module that can be inserted into and removed from the optical path of the objective lens 130, and a sensor 130S for detecting the inserted and removed state of the optical module 136. In the first embodiment, as described in detail later, when the optical module 136 is not disposed in the optical path of the objective lens 130, a posterior eye observation optical system 300 (see also FIG. 3) is configured as the observation optical system, and the ophthalmic device 110 thereby obtains an image of the posterior eye of the subject's eye 12. On the other hand, when the optical module 136 is inserted into the optical path of the objective lens 130, an anterior eye observation optical system 400 (see also FIG. 4) is configured as the observation optical system, and the ophthalmic device 110 thereby obtains an image of the anterior eye of the subject's eye 12. In the first embodiment, as described in detail later, the optical module 136 is inserted into and removed from the optical path of the observation optical system manually or automatically by an operator (e.g., an ophthalmologist). The optical module 136 moves on a rail (not shown) or is inserted into or removed from the optical path between the first lens group 134 and the second lens group 132 by rotational movement of a turret. The sensor 130S that detects the insertion/removal state of the optical module 136 for anterior segment observation may be a sensor that detects either that the optical module 136 is inserted into or removed from the imaging optical system, or may be a sensor that can detect both.
The sensor 130S is an example of the "insertion detection means" of the technology of the present disclosure.

Hereinafter, in this embodiment, the case where the subject's eye 12 is observed with the optical module 136 for anterior eye observation not disposed in the optical path of the imaging optical system is referred to as the posterior eye observation mode (first mode). Also, the case where the subject's eye 12 is observed with the optical module 136 disposed in the optical path of the imaging optical system is referred to as the anterior eye observation mode (second mode).

2, the imaging optical system 116A further includes an optical module 138 that is different from the optical module 136 for anterior eye observation. The optical module 138 is mainly used in the posterior eye observation mode, and is therefore hereinafter referred to as the optical module 138 for posterior eye observation. The optical module 138 for posterior eye observation includes a beam splitter 178. The beam splitter 178 is disposed in the optical path between the objective lens 130 and the horizontal scanning unit 142, more specifically, between the first lens group 134 and the horizontal scanning unit 142.

Next, the configuration of each of the imaging optical systems 116A in the posterior eye observation mode and the anterior eye observation mode will be described with reference to Figures 3 and 4. Figure 3 shows the posterior eye observation optical system 300 in the posterior eye observation mode. The optical module 136 for anterior eye observation is removed from the optical path of the objective lens 130. Figure 4 shows the anterior eye observation optical system 400 in the anterior eye observation mode. The optical module 136 for anterior eye observation is inserted into the optical path of the objective lens 130, specifically, the optical path between the first lens group 134 on the horizontal scanning unit 142 side and the second lens group 132 on the test eye side. In the posterior eye observation optical system 300 (Figure 3), the parallel light beams of three angles of the parallel light beams supplied from the scanning surface represented by the horizontal scanning unit 142 are shown as being focused on the fundus 12A of the test eye 12 through two positive lens groups (the first lens group 134 and the second lens group 132). In the anterior segment observation optical system 400 (Figure 4), parallel light beams at the same three angles shared from the horizontal scanning unit 142 are focused onto the cornea of the test eye 12 by two positive lens groups (the first lens group 134 and the second lens group 132) and an optical element inserted between them (the negative lens 162, described in detail later) as shown in the diagram.

In the posterior segment observation optical system 300, as shown in FIG. 2, the vertical scanning units 120, 148 and the horizontal scanning unit 142 are arranged so as to be conjugate with the pupil position Pp of the test eye 12. In the SLO optical system, the SLO laser light scanned by the vertical scanning unit 120 and the horizontal scanning unit 142 passes through the objective lens 130 and is two-dimensionally angularly scanned around the pupil position Pp of the test eye 12. As a result, the focal point of the SLO laser light is two-dimensionally scanned on the fundus 12A. Similarly, in the OCT optical system, the measurement light scanned by the vertical scanning unit 148 and the horizontal scanning unit 142 passes through the objective lens 130 and is two-dimensionally angularly scanned around the pupil position Pp of the test eye 12. As a result, the focal point of the measurement light is two-dimensionally scanned on the fundus 12A. In a posterior segment observation mode in which images are acquired using the posterior segment observation optical system 300, a two-dimensional fundus image is acquired by the SLO unit 18, and a tomographic image of the fundus is acquired by the OCT unit 20. As described below, during the period in which the OCT unit 20 is acquiring a tomographic image of the fundus, the SLO unit 18 continues to acquire two-dimensional images of the fundus sequentially. The multiple SLO images acquired sequentially are used as images for eye tracking during OCT imaging.

In the anterior eye observation optical system 400, as shown in FIG. 4, an optical module 136 for anterior eye observation is inserted in the optical path of the objective lens 130, specifically, in the optical path between the first lens group 134 with positive refractive power and the second lens group 132 with positive refractive power that constitute the objective lens 130. The optical module 136 has an optical element such as a lens inside. In this embodiment, the optical element is a lens 162 with negative power as a switching lens. When the negative lens 162 is placed on the optical axis of the objective lens 130, the negative lens 162 acts as a switching lens for switching the posterior eye observation optical system 300 to the anterior eye observation optical system 400. Hereinafter, the lens 162 will be referred to as the negative lens 162 or the switching lens 162. When the negative lens 162 is inserted into the optical path of the objective lens 130, the scanning position of the horizontal scanning unit 142 and the pupil position Pp of the subject's eye 12 are not conjugate, and the parallel light from the scanning position of the horizontal scanning unit 142 is focused on the anterior eye. The diameter of the light beam passing through the negative lens 162 is smaller than the diameter of the light beam passing through each of the first lens group 134 and the second lens group 132. Therefore, the effective diameter of the negative lens 162 is smaller than the effective diameter of the lens group constituting the objective lens 130. The negative lens 162 is smaller than the first lens group 134 and the second lens group 132. Therefore, the optical module 136 can be configured to be small. Note that the optical element is not limited to the negative lens 162, and instead of the negative lens 162, an optical member such as a Fresnel lens or a DOE (Diffractive Optical Element) may be used.

Next, the configuration and function of the optical module 136 for observing the anterior segment of the eye will be described in detail. As shown in FIG. 3, the optical module 136 includes the switching lens 162 described above, a switching lens driving unit 162M, a beam splitter 170, a fixation lamp 164, cameras 166A and 166B, and illumination devices 168A and 168B. The switching lens driving unit 162M as an optical element driving unit minutely moves the switching lens 162 within a plane intersecting the optical axis of the objective lens 130, for example, within a plane perpendicular to the optical axis, under the control of the CPU 16A. The fixation lamp 164 generates visible light and is used to guide and fix the line of sight of the subject's eye 12. The illumination devices 168A and 168B are infrared light sources and are used to illuminate the anterior segment of the subject's eye 12. The infrared light source emits infrared light having a longer or shorter wavelength than the wavelength of the measurement light emitted from the OCT unit 20, for example. The cameras 166A and 166B receive the infrared light reflected by the anterior segment of the subject's eye 12, and generate an image of the anterior segment, for example, the cornea reflected light. The beam splitter 170 transmits the OCT measurement light, and reflects the visible light emitted from the fixation lamp 164 and the infrared light emitted from the illumination devices 168A and 168B. The visible light and infrared light reflected by the beam splitter 170 are directed to the subject's eye 12 via the second lens group 132 of the objective lens 130. The infrared light reflected by the anterior segment is reflected by the beam splitter 170 and detected by the cameras 166A and 166B. The cameras 166A and 166B are preferably equipped with a light receiving element such as a CCD area sensor or a CMOS area sensor, and are controlled to output a plurality of reflected light images of the subject's eyes 12 in time series, for example, as a video. Each of the cameras 166A and 166B captures an image of the anterior segment of the subject's eye 12 from a different direction. The CPU 16A processes the images of the anterior segment (e.g., corneal reflected light images) obtained from each of the cameras 166A and 166B to calculate the positions of the anterior segment and pupil of the subject's eye 12. The calculated position information of the anterior segment and pupil is used to align the subject's eye 12 with the ophthalmic device 110 before starting OCT imaging of the anterior segment.
The cameras 166A and 166B are an example of a "light receiving element" of the technology of the present disclosure. The lighting devices 168A and 168B, the cameras 166A and 166B, and the CPU 16A are an example of a "motion detection means" of the technology of the present disclosure.

The position information of the anterior segment and the pupil calculated by the CPU 16A, i.e., information on the movement of the subject's eye 12, is used as information for performing eye tracking during the acquisition of the tomographic image of the anterior segment. In the anterior segment observation mode, eye tracking is realized by the switching lens driver 162M changing the position of the switching lens 162 based on the position information of the anterior segment and the pupil calculated by the CPU 16A. The measurement light of the OCT is irradiated to the anterior segment of the subject's eye 12 through the switching lens 162 as shown in FIG. 4. The switching lens driver 162M changes the irradiation position of the measurement light on the anterior segment by moving the switching lens 162 in a plane intersecting the optical axis of the objective lens 130. The CPU 16A controls the switching lens driver 162M to move the switching lens 162 based on the position information of the anterior segment and the pupil calculated in real time. As a result, the CPU 16A changes the irradiation position of the measurement light on the anterior segment of the subject's eye 12 in accordance with the movement of the subject's eye 12. As described above, the driving range of the switching lens 162 is within a plane intersecting the optical axis of the objective lens 130, and examples of such a range include a plane perpendicular to the optical axis and a curved surface intersecting the optical axis with a point on the optical axis as a center. Note that an anti-vibration lens mechanism used in cameras and the like can be used as the switching lens driving unit 162M. Examples of such techniques include Japanese Patent Application Publication No. 2007-240736, Japanese Patent Application Publication No. 2009-282448, Japanese Patent Application Publication No. 2010-011302, and Japanese Patent Application Publication No. 2012-173301. Unless otherwise specified, the contents of these documents are incorporated by reference.

Next, the configuration and function of the optical module 138 for posterior segment observation will be described in detail. As shown in FIG. 2, the optical module 138 for posterior segment observation is disposed in the optical path between the horizontal scanning unit 142 and the objective lens 130. The optical module 138 for posterior segment observation includes a beam splitter 178 and a module body 138H. The module body 138H includes a fixation lamp 172, cameras 174A and 174B, and illumination devices 176A and 176B.

The fixation lamp 172 emits visible light to guide and fix the line of sight of the subject's eye 12. The visible light emitted from the fixation lamp 172 is reflected by the beam splitter 178 and enters the subject's eye 12 via the objective lens 130.

The illumination devices 176A and 176B emit infrared light as illumination light for illuminating the anterior segment of the subject's eye 12. The infrared light source emits infrared light of a wavelength different from, for example, the measurement light emitted from the OCT unit 20 and the IR light emitted from the SLO unit 18. The illumination light is reflected by the beam splitter 178 and illuminates the anterior segment of the subject's eye 12 via the objective lens 130.

The cameras 174A and 174B receive the illumination light reflected by the anterior segment of the subject's eye 12 and generate an image of the anterior segment, for example, the cornea. The anterior segment of the subject's eye 12 is photographed by the two cameras 174A and 174B from different directions. The beam splitter 178 transmits the measurement light emitted from the OCT unit 20 and the IR light emitted from the SLO unit 18, and reflects the visible light emitted from the fixation lamp 172 and the infrared light emitted from the illumination devices 176A and 176B. The visible light and infrared light reflected by the beam splitter 178 are directed to the subject's eye 12 via the objective lens 130. The infrared light reflected by the anterior segment is reflected by the beam splitter 178 and detected by the cameras 174A and 174B. The cameras 166A and 166B are preferably equipped with light receiving elements such as a CCD area sensor or a CMOS area sensor, and are controlled to output reflected light images of a plurality of subjects' eyes 12 in time series, for example as a video. Each of the cameras 166A and 166B captures an anterior segment of the subject's eye 12 from a different direction. The CPU 16A processes the anterior segment images obtained by each camera and calculates the positions of the anterior segment and pupil of the subject's eye 12. The calculated position information of the anterior segment and pupil is used to align the subject's eye 12 with the ophthalmic device 110 before starting posterior segment tomography.

In this embodiment, the optical module 138 is always inserted into the optical path of the imaging optical system 116A, but this is not the only possible example. The optical module 138 is configured to be insertable into and removable from the optical path of the imaging optical system 116A, and may be removed from the optical path of the imaging optical system 116A during the anterior eye observation mode. In this case, the optical module 138 is manually or automatically operated by an operator (e.g., an ophthalmologist) and is inserted into or removed from the optical path of the observation optical system by moving on a rail (not shown) or by rotating a turret.

Next, the optical configuration in the posterior eye observation mode and the anterior eye observation mode will be described. The upper diagram of FIG. 5 shows an overview of the posterior eye observation optical system in the posterior eye observation mode (first mode). The optical module 136 for anterior eye observation is not inserted in the optical path of the objective lens 130. On the other hand, the lower diagram of FIG. 5 shows an overview of the anterior eye observation optical system in the anterior eye observation mode (second mode). The optical module 136 is inserted in the optical path of the objective lens 130. Note that in the schematic diagram of the anterior eye observation optical system, for ease of explanation, only the switching lens 162 is shown as the optical module 136.

In the posterior segment observation optical system (upper diagram in FIG. 5), the multiple lens groups constituting the objective lens 130, i.e., the positive first lens group 134 and the positive second lens group 132, form an afocal system, and the scanning center (Ps in the diagram) in the horizontal scanning unit 142 is conjugate with the pupil position Pp of the subject's eye 12. Here, if the focal lengths of the first lens group 134 and the second lens group 132 are f1 and f2, respectively, the distance (group spacing) d between the first lens group 134 and the second lens group 132 is given by:
d = f1 + f2
It is.
The magnification β is
β=−f2/f1
It is.

In the posterior segment observation mode (first mode) of the first embodiment, the scanning position Ps of the horizontal scanning unit 142 is conjugate with the pupil position Pp of the subject's eye 12. Parallel light from the scanning position Ps of the horizontal scanning unit 142 passes through the pupil position Pp of the subject's eye 12 as approximately parallel light at a predetermined angle, and is focused on the fundus 12A by the subject's eye 12. The focusing position at the fundus 12A of the measurement light emitted from the OCT unit 20 is determined depending on the position of the vertical scanning unit 120 and the scanning angle at the position (Ps) of the horizontal scanning unit 142. This makes it possible to set a desired scanning position and scanning range when photographing or observing the fundus 12A.

Next, the anterior segment observation optical system (lower diagram in FIG. 5) will be described. In this observation optical system, the switching lens 162 of the optical module 136 for anterior segment observation is inserted into the optical path of the objective lens 130.

In the anterior segment observation mode (second mode), a switching lens 162, which is a negative lens, is inserted between the first lens group 134 and the second lens group 132. In the anterior segment observation mode (second mode), the scanning position Ps of the horizontal scanning unit 142 and the pupil position Pp of the subject's eye 12 are not conjugated, and the parallel light from the scanning position Ps of the horizontal scanning unit 142 is focused on the anterior segment. The focusing position at the anterior segment of the measurement light emitted from the OCT unit 20 is determined depending on the scanning angle at the position (Ps) of the scanning unit. This makes it possible to observe the anterior segment.

Here, the arrangement of the switching lens 162 in the anterior eye observation mode (second mode) will be described. The focal length of the switching lens 162 is f3, the distance between the first lens group 134 and the switching lens 162 is x, the object distance of the switching lens 162 when parallel light is incident on the first lens group 134 from the scanning position Ps is S3, and the image distance is S3'. Note that the image position P3' in the figure is the image position by the switching lens 162 when parallel light is incident on the first lens group 134 from the scanning position Ps, and the image position P3' is conjugate with the pupil position Pp of the subject's eye 12. From the imaging equation for the switching lens 162,


It is.
S3 = f1 - x
Than,


is obtained.

Next, for the second lens group 132, similarly, if the object distance of the second lens group 132 is S2 and the image distance is S2' when parallel light is incident on the first lens group 134 from the scanning position Ps, then the imaging equation for the second lens group 132 gives:


Note that S2' is substantially the distance between the second lens group 132 and the subject's eye 12, that is, the so-called working distance WD. As can be seen from FIG. 5,
S2=S3′+d−x
And from this,


is obtained.

Substituting the above formula (1) into formula (2),


is obtained.
By rearranging the above equation (3) with respect to x, the following equation is obtained.

Using this equation (4), once the focal length f3 of the switching lens 162 is determined, the value of its position x can be found.

In addition, when the light between the two positive first lens group 134 and the second lens group 132 is parallel light, f2=S2′. Therefore, from the above formula (3),
x=f1+f3...(5)
This results in a simple relationship (5).

Approximately, it is possible to configure the system by placing a switching lens 162 between the first lens group 134 and the second lens group 132 according to this relational expression (5). This relational expression (5) is a theoretical configuration, even though it is the case that the two positive first lens group 134 and the second lens group 132 are completely afocal systems and the light between the two groups is completely parallel light. Needless to say, a practical solution is to appropriately select the shape, thickness, refractive index, etc. of each lens by performing appropriate aberration calculations in order to obtain an aberration structure suitable for the anterior eye observation mode (second mode).

In the first embodiment, as shown in FIG. 5, the distance (working distance WD) between the second lens group 132 and the subject's eye 12 does not change whether it is the posterior eye observation mode (first mode) or the anterior eye observation mode (second mode). Therefore, there is no need to readjust the alignment between the subject's eye 12 and the imaging optical system 116A according to the change of each observation mode, and therefore there is no need to force the subject to move. Since it is possible to smoothly and quickly switch between anterior eye photography and posterior eye photography, the time required for a series of photographs can be shortened. In addition, since the switching lens 162 is small, the insertion and removal mechanism of the switching lens 162 can be realized simply and compactly.

Next, a method for acquiring a tomographic image of the test eye 12 using the ophthalmic apparatus 110 according to the first embodiment will be described. FIG. 6 shows a flowchart of the tomographic image generation process. The tomographic image generation process starts when a tomographic image generation start button (not shown) is turned on. The tomographic image generation process is realized by the CPU 16A executing a tomographic image generation process program stored in the ROM 16C. Note that the tomographic image generation process program may be stored in an external storage device (not shown) instead of the ROM 16C.

First, when attempting to obtain a tomographic image of the posterior segment of the subject's eye 12, for example, the fundus 12A, the operator does not use the optical module 136 for observing the anterior segment (see FIG. 3). On the other hand, when attempting to generate a tomographic image of the anterior segment of the subject's eye 12, for example, the cornea, the operator inserts the optical module 136 into the optical path of the imaging optical system 116A (see FIG. 4).

In step 202, the CPU 16A determines whether or not the optical module 136 is inserted into the photographing optical system 116A based on the input state of the signal from the sensor 130S.

If it is determined that the optical module 136 is inserted into the optical path, the tomographic image generation process proceeds to step 204. In step 204, the observation mode is set to the anterior segment observation mode (second mode).

If it is determined that the optical module 136 is not inserted in the optical path, the tomographic image generating process proceeds to step 214. In step 214, the observation mode is set to the posterior eye observation mode (second mode).
The CPU 16A and the process of step 202 are an example of a "mode selection means" of the technology of the present disclosure. That is, the CPU 16A sets either the posterior eye observation mode (first mode) or the anterior eye observation mode (second mode) according to the determination result of step 202.

In step 204, alignment between the subject's eye 12 and the photographing optical system 116A is performed using the optical module 136. Specifically, the CPU 16A turns on the fixation lamp 164, the illumination devices 168A and 168B, and the cameras 166A and 166B.
The operator urges the patient to gaze at the fixation lamp 164. When the patient gazes at the fixation lamp 164 from the front, the line of sight of the subject's eye 12 coincides with the optical axis of the photographing optical system 116A. The CPU 16A displays the anterior segment images of the subject's eye 12 output from the cameras 166A and 166B on the monitor of the input/display device 16E. The operator checks from the anterior segment image displayed on the monitor of the input/display device 16E whether the pupil of the subject's eye 12 is in an appropriate position.

The alignment between the subject's eye 12 and the photographing optical system 116A may be automated by the CPU 16A. The CPU 16A detects the apex (center position) of the cornea based on, for example, a corneal reflection light image in a still image or video of the anterior part of the subject's eye 12 output from the cameras 166A and 166B. The CPU 16A calculates the deviation (amount of deviation and direction of deviation) between the detected apex of the cornea and the optical axis of the photographing optical system 116A (ophthalmic device 110). The CPU 16A may control the photographing optical system driving unit 116M to move the photographing optical system 116A so that the optical axis of the photographing optical system 116A coincides with the position of the apex of the cornea based on the amount of deviation and the direction of deviation. In addition, for fine adjustment in the XY direction, the switching lens driving unit 162M may be controlled to move the switching lens 162 within a plane intersecting the optical axis of the photographing optical system 116A.

When the alignment between the test eye 12 and the imaging optical system 116A is complete, the tomographic image generation process proceeds to step 206. In step 206, the CPU 16A starts an OCT scan to obtain three-dimensional image data of the anterior segment of the test eye 12. Specifically, the CPU 16A operates the OCT unit 20 and controls the horizontal scanning unit 142 and the vertical scanning unit 148 to perform two-dimensional scanning of the measurement light in a pre-specified area of the anterior segment of the test eye 12.

However, while the measurement light is being two-dimensionally scanned in a specified area of the anterior segment of the test eye 12, the test eye 12 may move unintentionally due to fixation eye movement or the like, even if the patient is gazing at the fixation lamp 164. Since unintentional movement of the test eye may cause motion artifacts in the OCT image, correction of the scan position of the measurement light, i.e., eye tracking, is performed during the period when three-dimensional image data of the test eye 12 is acquired. By eye tracking, the scan position of the measurement light follows the movement of the test eye 12 in real time. Therefore, in steps 208 and 210, the CPU 16A executes a process of making the irradiation position of the measurement light in the anterior segment follow the movement of the test eye 12. Specifically, the process is as follows.

In step 208, the CPU 16A controls the cameras 166A and 166B of the optical module 136 to sequentially photograph the anterior part of the eye 12, for example, the cornea, at predetermined time intervals. The CPU 16A extracts the center position of the cornea from each of the sequential images output from the cameras 166A and 166B, and calculates the deviation information (such as the deviation amount, the deviation direction, and the deviation vector) between the corneal center position in the previous image (the n-1th image) and the corneal center position in the current image (the nth image) as the movement of the eye 12. Here, n is a natural number equal to or greater than 2, and indicates the number of times the cornea has been photographed at each predetermined time interval.
The deviation information (such as deviation amount, deviation direction, and deviation vector) is an example of "motion information" of the technology of the present disclosure.

In step 210, the CPU 16A executes eye tracking control (second eye tracking control) in the anterior eye observation mode (second mode). In this eye tracking control, the switching lens 162 and the switching lens driving unit 162M are used. As described above, the switching lens driving unit 162M moves the switching lens 162 in a plane intersecting the optical axis of the objective lens 130. By slightly moving the switching lens 162, the irradiation position of the measurement light on the anterior eye can be changed. Specifically, the CPU 16A feedback controls the switching lens driving unit 162M to move the switching lens 162 based on the deviation information of the center position of the cornea calculated every predetermined time. As a result, the irradiation position of the measurement light on the anterior eye can be made to follow the movement of the subject's eye 12.

In step 212, CPU 16A determines whether the OCT scan is completed for the observation area specified by the operator. If it is determined that the OCT scan is not completed, the tomographic image generation process returns to step 208, and if it is determined that the OCT scan is completed, the tomographic image generation process ends. In this way, eye tracking control (steps 208, 210) in the anterior eye observation mode is performed until the OCT scan is completed, that is, during the period when the measurement light is irradiated to the test eye.

When the tomographic image generation process is completed, the CPU 16A turns off the fixation light 164, cameras 166A, 166B, and lighting devices 168A, 168B of the optical module 136, as well as the OCT unit 20, and terminates the acquisition of three-dimensional image data of the anterior segment.

If it is not determined in step 202 that the optical module 136 is inserted in the optical path of the objective lens 130 (see FIG. 3), then in step 214, alignment is performed between the subject eye 12 and the imaging optical system 116A using the optical module 138 for posterior eye observation. The processing in step 214 is similar to the alignment processing in step 204 in that the elements (172-176B) of the optical module 138 for the posterior eye are used, and therefore a description thereof will be omitted. The difference is whether the optical module 136 for anterior eye observation or the optical module 138 for posterior eye observation is used.

When the alignment between the test eye 12 and the imaging optical system 116A is completed in step 214, the tomographic image generation process proceeds to step 216. In step 216, the CPU 16A starts an OCT scan to acquire three-dimensional image data of the posterior segment. As with the acquisition of three-dimensional image data of the anterior segment (step 206), while the OCT scan is being performed on the posterior segment of the test eye 12, the test eye 12 may move due to fixational eye movement or the like, so the CPU 16A uses eye tracking processing in steps 218 and 220 to make the irradiation position of the measurement light on the fundus follow the movement of the test eye 12. Specifically, this is as follows.

In step 218, CPU 16A operates SLO unit 18 to continuously acquire two-dimensional fundus images during the period in which three-dimensional fundus data is acquired. Preferably, CPU 16A acquires IR-SLO images by emitting IR light from SLO unit 18. Since the SLO optical system and the OCT optical system share the objective lens 130 and horizontal scanning unit 142, the two-dimensional fundus images acquired by SLO unit 18 include the acquisition area of the three-dimensional image data specified by the operator. CPU 16A extracts at least one feature point from each of the two-dimensional fundus images acquired sequentially by SLO unit 18. Examples of feature points include the pattern of blood vessels, the branching points of blood vessels, and the positions of the optic disc and macula. Each time the CPU 16A acquires a two-dimensional fundus image from the SLO unit 18, it compares the feature points extracted from the current image (nth image) with the feature points extracted from the previously acquired image (n-1th image) and calculates the deviation information of the feature points (amount of deviation, direction of deviation, vector of deviation, etc.) as the movement of the test eye 12.

In step 220, the CPU 16A executes the first eye tracking control in the fundus observation mode (first mode) based on the deviation information calculated in step 218. Specifically, the CPU 16A feedback-controls the horizontal scanning unit 142 and the vertical scanning unit 148 based on the deviation information of the feature points calculated each time an SLO image is acquired, so that the irradiation position of the measurement light on the fundus 12A follows the movement of the subject's eye 12.

In step 222, CPU 16A determines whether acquisition of three-dimensional image data for the area specified by the operator has been completed. If it is determined that acquisition of three-dimensional image data has not been completed, the tomographic image generation process returns to step 218, and if it is determined that acquisition of three-dimensional image data has been completed, the tomographic image generation process ends. In this way, the second eye tracking control is performed until the OCT scan is completed, that is, during the period during which the measurement light is irradiated to the test eye.

When completing the tomographic image generation process, the CPU 16A turns off the fixation light 172, cameras 174A, 174B, lighting devices 176A, 176B, OCT unit 20, and SLO unit 18 of the optical module 138 for posterior eye observation, and terminates the acquisition of three-dimensional image data of the posterior eye.

The ophthalmic device 110 of the first embodiment described above can provide a device that acquires three-dimensional image data of both the posterior and anterior segments of the test eye 12 using an optical module 136 for observing the anterior segment with a single ophthalmic device.

In addition, the ophthalmic device 110 according to the first embodiment can switch between the posterior eye observation optical system and the anterior eye observation optical system by inserting and removing the optical module 136 for anterior eye observation into and from the optical path between the first lens group 134 and the second lens group 132 constituting the objective lens 130, so that the working distance WD between the objective lens 130 (particularly the second lens group 132) and the subject's eye 12 does not change in each optical system (300, 400). As a result, in the above-mentioned step 204 (anterior eye observation mode) and step 214 (posterior eye observation mode), it is not necessary to redo the alignment between the subject's eye 12 and the photographing optical system 116A, so that the switching between the posterior eye observation mode and the anterior eye observation mode can be performed smoothly.

In addition, in the ophthalmic device 110 according to the first embodiment, the optical element of the optical module 136 for observing the anterior segment of the eye can be a small lens with an effective diameter smaller than that of the objective lens 130 (the first lens group 134 and the second lens group 132), so that the optical module 136 can be made compact. Therefore, it is easy to switch between the optical system for observing the posterior segment of the eye and the optical system for observing the anterior segment of the eye.

In addition, the ophthalmic device 110 according to the first embodiment switches eye tracking control according to a posterior eye observation mode (first mode) for acquiring three-dimensional image data of the posterior eye of the subject's eye 12 and an anterior eye observation mode (second mode) for acquiring three-dimensional image data of the anterior eye of the subject's eye 12, so that eye tracking control optimal for each mode can be performed. In addition, since the optical modules 136 and 138 are used according to each mode, troublesome adjustments such as focus adjustment of the fixation lamp are not required.

As a result, in the first embodiment, the convenience of the ophthalmic device 110 can be improved.

In the first embodiment described above, the operator manually removes the optical module 136 for the anterior eye from the optical path of the imaging optical system 116A or inserts it into the optical path, but the technology of the present disclosure is not limited to this. For example, a mechanism is provided for automatically removing the optical module 136 for the anterior eye from the optical path or inserting it into the optical path. When a posterior eye tomographic image generation button (not shown) is turned on or when an anterior eye tomographic image generation button is turned on, the CPU 16A may control the mechanism to automatically remove the optical module 136 for observing the anterior eye from the optical path or insert it into the optical path. The mechanism is an example of an "optical module driving means" of the technology of the present disclosure.

In the first embodiment, the switching lens 162 is arranged to be movable within a plane perpendicular to the optical axis of the objective lens 130, but the technology of the present disclosure is not limited to this. For example, the switching lens 162 may be arranged to be rotatable around a point on the optical axis of the objective lens 130 as the center of rotation. In this case, in steps 204, 210, and 214, the switching lens 162 is rotated within a curved surface around a point on the optical axis of the objective lens 130 as the center of rotation.

In the first embodiment, the objective lens 130, the horizontal scanning unit 142, and the relay lens device 140 are arranged in order from the test eye 12 as a common optical system shared by the SLO optical system and the OCT optical system, but the technology disclosed herein is not limited to this. Instead of a configuration in which the horizontal scanning unit 142 is shared by the SLO optical system and the OCT optical system, a horizontal scanning unit and a vertical scanning unit may be provided in each optical system.

[Second embodiment]

Next, the second embodiment will be described. The configuration of the second embodiment is substantially the same as that of the first embodiment, so the same parts are given the same reference numerals and their explanation will be omitted, and mainly the different parts will be described.

FIG. 7 shows a schematic configuration of an imaging optical system 116B according to the second embodiment.
In the imaging optical system 116A of the first embodiment, an optical module 136 for observing the anterior segment of the eye is disposed between the first lens group 134 and the second lens group 132 so as to be detachable therefrom.
In contrast to this, in the photographing optical system 116B of the second embodiment, an optical module 136B for observing the anterior eye segment is removably disposed between the second lens group 132 and the subject's eye 12. Whether or not the optical module 136B is inserted into the photographing optical system 116B is determined by the CPU 16A based on a signal output from the sensor 130S, as in the first embodiment.

The optical module 136B of the second embodiment is similar to the configuration of the optical module 136 of the first embodiment, and includes a switching lens 162B, a switching lens driver 162MB, a beam splitter 170, a fixation lamp 164, cameras 166A and 166B, and lighting devices 168A and 168B. The functions of each component are similar to those of the components constituting the optical module 136 of the first embodiment, and therefore illustrations and explanations are omitted, except for the switching lens 162B and the switching lens driver 162MB. In addition, the optical module 138 for posterior eye observation of the second embodiment is the same as the optical module for posterior eye observation of the first embodiment, and therefore explanations are omitted.

When the optical module 136B is inserted into the imaging optical system 116B, the switching lens 162B is positioned in the optical path between the second lens group 132 of the objective lens 130 and the subject's eye 12. The switching lens 162B in the second embodiment is a positive lens. As in the first embodiment, the CPU 16A drives the switching lens driving unit 162MB in response to the detected movement of the subject's eye 12 as described in steps 208 and 210, and moves the switching lens 162B in a plane intersecting the optical axis of the objective lens 130. This changes the irradiation position of the measurement light emitted from the OCT unit 20 on the anterior segment of the subject's eye 12, and eye tracking control is performed during the acquisition period of three-dimensional image data of the anterior segment.

In the second embodiment, the optical module 136B is inserted between the second lens group 132 and the subject's eye 12, and therefore the working distance WD between the subject's eye 12 and the photographing optical system 116B changes between the fundus observation optical system and the anterior segment observation optical system. Therefore, in the above-mentioned step 204 (anterior segment observation mode) and step 214 (posterior segment observation mode), alignment in the Z-axis direction between the subject's eye 12 and the photographing optical system 116B is performed in each step.

In the second embodiment, the switching lens 162B as an optical element inserted and removed between the second lens group 132 and the test eye 12 is a positive lens, but this is not limited to this. When the optical element is inserted into the optical path of the imaging optical system 116B, it is sufficient that the measurement light emitted from the OCT unit 20 is focused on the anterior segment of the test eye 12, and the optical element may be, for example, a lens having negative power (negative lens).

[Third embodiment]

Next, the third embodiment will be described. The configuration of the third embodiment is substantially the same as that of the first embodiment, so the same parts are given the same reference numerals and their explanation will be omitted, and mainly the different parts will be described.

Figure 8 shows an example of an imaging optical system 116C in which an optical module 136C for observing the anterior segment is configured to be insertable and detachable.

The optical module 136C is removably arranged between the first lens group 134 constituting the objective lens 130 and the horizontal scanning unit 142. The optical module 136C in a state removed from the imaging optical system 116C (posterior eye observation optical system) is shown by a solid line, and the optical module 136C in a state inserted into the imaging optical system 116C (anterior eye observation mode) is shown by a dashed line. As in the first and second embodiments, the CPU 16A determines whether the optical module 136C is inserted into the imaging optical system 116C based on a signal output from the sensor 140D.

The optical module 136C for anterior segment observation according to the third embodiment includes a switching lens 162C and a switching lens drive unit 162MC. As shown in the figure, the optical module 138 for posterior segment observation according to the third embodiment has the same configuration as the optical module for posterior segment observation according to the first embodiment, and therefore the description thereof is omitted.

Unlike the optical modules 136 and 136B of the first and second embodiments, the optical module 136C does not include the beam splitter 170, the fixation lamp 164, the cameras 166A and 166B, and the illumination devices 168A and 168B. In step 204 of the anterior eye observation mode, the alignment between the subject's eye 12 and the photographing optical system 116C is performed using the optical module 138 for posterior eye observation. Specifically, in step 204, the CPU 16A turns on the fixation lamp 172, the illumination devices 176A and 176B, and the cameras 174A and 174B of the optical module 138 for posterior eye observation. The operator prompts the patient to gaze at the fixation lamp 172. When the patient gazes at the fixation lamp from the front, the line of sight of the subject's eye 12 coincides with the optical axis of the photographing optical system 116C. The CPU 16A displays the anterior eye image of the subject's eye 12 output from the cameras 174A and 174B on the monitor of the input/display device 16E. The operator checks from the anterior eye image displayed on the monitor of the input/display device 16E whether the pupil of the subject's eye 12 is in an appropriate position.

When the optical module 136C is inserted into the imaging optical system 116C, the switching lens 162C is located in the optical path between the first lens group 134 of the objective lens 130 and the horizontal scanning unit 142. The switching lens 162C in the third embodiment is a negative lens. As in the first and second embodiments, the CPU 16A drives the switching lens driving unit 162MC in response to the detected movement of the subject's eye 12 as described in steps 208 and 210 to move the switching lens 162C in a plane intersecting the optical axis of the objective lens 130. This changes the irradiation position of the measurement light emitted from the OCT unit 20 on the anterior segment of the subject's eye 12, and eye tracking control is performed during the acquisition period of three-dimensional image data of the anterior segment.

In the third embodiment, the switching lens 162C as an optical element inserted and removed between the first lens group 134 and the horizontal scanning unit 142 is a negative lens, but this is not limited thereto. When the optical element is inserted into the optical path of the imaging optical system 116C, it is sufficient that the measurement light emitted from the OCT unit 20 is focused on the anterior segment of the test eye 12, and the optical element may be, for example, a lens having positive power (positive lens).

[Further variations]

In each of the examples described above, the objective lens 130 has a positive first lens group 134 (G1), but the technology disclosed herein is not limited to this, and the first lens group 134 may also be a lens group having negative power (negative lens).

In each of the above-mentioned examples, focus adjustment may be performed. The focus adjustment is not limited to being performed by the autofocus device alone, and may involve moving at least one of the optical system from the second lens group 132 of the objective lens to the light source side, for example, the second lens group 132 of the objective lens, the first lens group 134, the switching lens 162, and the lenses 144 and 146, including the autofocus device.

In each of the examples described above, it is also possible to prepare multiple optical elements such as switching lenses with different powers, and depending on the shape of the anterior segment (e.g., the cornea) obtained in advance, select from the multiple optical elements an optical element that can focus light at the corneal position depending on the shape of the cornea, etc.

In each of the examples described above, furthermore, depending on the shape of the anterior segment (e.g., the cornea), the position at which an optical element such as a switching lens is inserted is switched to between the first lens group 134 and the second lens group 132, or between the horizontal scanning unit 142 and the first lens group 134, and an optical element capable of focusing light according to the corneal position is selected from among a plurality of optical elements such as switching lenses having different powers, and inserted at the switched position.

In each of the above-described examples, the interference light is detected by one detector in both the posterior eye observation mode (first mode) and the anterior eye observation mode (second mode), but the technology disclosed herein is not limited to this. For example, two detectors with different detection capabilities may be provided, and the interference light may be detected by one of the two detectors in the posterior eye observation mode (first mode), and by the other of the two detectors in the anterior eye observation mode (second mode).

The tomographic image generation process described above is merely an example. It goes without saying that unnecessary steps may be deleted, new steps may be added, or the order of the processes may be changed without departing from the spirit of the invention.

In each of the above-described examples, the tomographic image generation process is realized by a software configuration using a computer, but the technology of the present disclosure is not limited to this. For example, instead of a software configuration using a computer, the tomographic image generation process may be executed only by a hardware configuration such as an FPGA (Field-Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit). A part of the tomographic image generation process may be executed by a software configuration, and the remaining process may be executed by a hardware configuration.

110 Ophthalmology device 16A CPU
17 Image processing device 20B Sensor 20C First optical coupler 130S Sensor 136 Optical module 142 Horizontal scanning unit 148 Vertical scanning units 166A, 166B Cameras 168A, 168B Illumination device

Claims (10)

A light source that generates light for optical coherence tomography;
a light splitting means for splitting the light from the light source into a reference light and a measurement light;
A scanning means for scanning the measurement light;
an optical element that is disposed in an optical path of the measurement light and that emits the measurement light scanned by the scanning means to an eye to be examined;
an optical element driving means for moving the optical element within a plane intersecting an optical axis of the optical element;
A movement detection means for detecting the movement of the subject's eye;
a drive control means for controlling the optical element drive means based on information on the movement of the subject's eye detected by the movement detection means;
an interference light detection means for detecting interference light obtained by combining the return light from the subject's eye and the reference light;
an image generating means for forming a tomographic image of the subject's eye based on a detection signal detected by the interference light detecting means;
An optical coherence tomography apparatus comprising :
The optical element, the optical element driving means, and the motion detection means are modularized as an optical module.
An optical coherence tomography apparatus comprising: The optical coherence tomography apparatus according to claim 1, characterized in that the drive control means controls the optical element drive means during the period during which the measurement light is irradiated to the subject's eye. The movement detection means for detecting the movement of the subject's eye includes:
an infrared light source that generates infrared light;
a light receiving element that receives the infrared light reflected by the subject's eye and sequentially outputs a plurality of reflected light images of the subject's eye;
Equipped with
3. The optical coherence tomography apparatus according to claim 1, wherein movement information of the subject's eye is calculated based on the reflected light images of the subject's eye output from the light receiving element. The optical coherence tomography apparatus according to claim 3 , wherein the light receiving element is an area sensor that captures an image of an anterior segment of the subject's eye. The optical coherence tomography apparatus according to claim 1 , wherein the optical module includes a fixation lamp. 6. The optical coherence tomography apparatus according to claim 1, further comprising an optical module driving unit for inserting and removing the optical module into and from the optical path of the measurement light. The optical element is a lens.
7. An optical coherence tomography apparatus according to claim 1, wherein the optical coherence tomography apparatus comprises: An optical module that is detachable from an optical coherence tomography apparatus that acquires a tomographic image from interference light between a measurement light and a reference light that has passed through a subject's eye,
an optical element disposed in an optical path of the measurement light;
an optical element driving means for moving the optical element within a plane intersecting an optical axis of the optical element;
A movement detection means for detecting the movement of the subject's eye;
An optical module comprising: The motion detection means
an infrared light source that irradiates the subject's eye with infrared light;
a light receiving element that receives the infrared light reflected by the subject's eye and obtains a reflected light image of the subject's eye;
9. The optical module according to claim 8 , further comprising: 10. The optical module according to claim 8 , further comprising a fixation lamp.