Ophthalmic device and method for controlling the device

Abstract

To reduce the possibility of imaging of an eye to be examined failing.SOLUTION: An ophthalmologic device includes: driving means for driving an optical head part including an optical system for imaging an eye to be examined of a subject; control means for controlling the driving means so as to reduce a first amount of positional deviation between the eye to be examined and the optical head part; and notification means for notifying of the information on a posture of the subject when it is determined that a difference between a second amount of positional deviation acquired under the control of the driving means, which is acquired at the time later than the time that the first amount of positional deviation is acquired, and the first amount of positional deviation is different from an amount that the optical head part is driven between the time that the first amount of positional deviation is acquired and the time that the second amount of positional deviation is acquired.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The disclosed technology relates to an ophthalmic apparatus and a control method for the ophthalmic apparatus. [Background technology]

[0002] As ophthalmic devices, devices for obtaining two-dimensional images of the fundus of a test eye (hereinafter referred to as fundus camera devices) and devices for obtaining tomographic images of a test eye using optical coherence tomography (OCT) with low-coherence light (hereinafter referred to as OCT devices) have been put to practical use.

[0003] Some of these devices are equipped with a fully automatic function that automatically performs various adjustments and then automatically captures images without the examiner having to operate them during the process.Patent Document 1 discloses an optical image measurement device that determines whether each state in the fully automatic function, such as alignment, focus, and position adjustment of the measurement image, is suitable, and captures images only when all are determined to be suitable. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2010-191172 A Summary of the Invention [Problem to be solved by the invention]

[0005] Depending on the posture of the subject, the failure may occur repeatedly no matter how many times the image is taken. For example, the subject may be in a posture where the head is away from the forehead rest, which may cause the eye movement to become unstable.

[0006] One of the objectives of the disclosed technology is to reduce the possibility of failure in photographing the subject's eye.

[0007] In addition to the above-mentioned objective, another objective of the present invention is to achieve effects that are derived from the various components shown in the description of the embodiments of the invention described below, and that cannot be obtained by conventional techniques. [Means for solving the problem]

[0008] One of the disclosed ophthalmic devices includes: An optical head unit including an optical system for imaging the subject's eye To move A driving means for driving the a control unit that controls the driving unit so as to reduce a first positional deviation amount between the eye to be examined and the optical head unit; When it is determined that a difference between the second positional deviation amount acquired at a time later than the time when the first positional deviation amount was acquired under the control of the driving means and the first positional deviation amount is different from an amount by which the optical head unit was driven between the time when the first positional deviation amount was acquired and the time when the second positional deviation amount was acquired, A movement of the subject's eye is detected. and a notification means for notifying information regarding the posture of the subject. Effect of the Invention

[0009] According to one of the disclosed techniques, it is possible to reduce the possibility of failure in photographing a subject's eye. [Brief description of the drawings]

[0010] [Figure 1] 1 shows a schematic configuration example of an apparatus according to an embodiment. [Diagram 2] 1 shows a flowchart of a method for controlling automatic alignment according to an embodiment. [Diagram 3] 1 shows a flowchart of a control method for detecting movement of an eye to be examined according to an embodiment. [Figure 4] 1 shows a flowchart of a control method for automatic coherence gate adjustment according to an embodiment. [Diagram 5] 1 shows a schematic configuration example of an optical head unit and a face receiving unit of an apparatus according to an embodiment. [Figure 6] FIG. 1 is a schematic diagram showing a change in position of an optical head unit and a test eye over time according to an embodiment; [Figure 7] 13 shows an example of display of notification content on a monitor according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, each embodiment of the present invention will be described in detail with reference to the drawings.

[0012] The device according to this embodiment is a device that detects the movement of the subject's eye in the control flow of automatic alignment and automatic coherence gate adjustment, and notifies the examiner of information regarding the subject's posture.

[0013] <Configuration> The ophthalmic apparatus of this embodiment includes a fundus image capturing unit that captures a two-dimensional fundus image and a tomographic image capturing unit that captures a three-dimensional tomographic image of the fundus of the subject's eye using information based on optical interference. The present embodiment will be described below with reference to FIG. 1, which shows a schematic configuration of the ophthalmic apparatus of this embodiment and its optical system. The ophthalmic apparatus includes an optical head unit 100, a spectroscope 200, and a control unit 300. The configurations of the optical head unit 100, the spectroscope 200, and the control unit 300 will be described in order below.

[0014] <Configuration of the Optical Head Unit 100 and the Spectrometer 200> The optical head unit 100, which is an inspection unit, is configured with a measurement optical system for capturing two-dimensional images and tomographic images of the anterior part Ea of the subject's eye E and the fundus Ef of the subject's eye. Various optical systems arranged in the optical head unit 100 will be described below. In the optical head unit 100, an objective lens 101 is installed facing the subject's eye E. That is, the optical head unit 100 may be configured to include, for example, an optical system for capturing an image of the subject's subject's eye. The optical system included in the optical head unit 100 may include, for example, a measurement optical system having an OCT measurement optical path including an objective optical system. In this case, the optical system included in the optical head unit 100 may or may not include various optical systems described later. The various optical systems described later may be configured to be included, for example, in a stage unit not shown, and in this case, the optical system inside the optical head unit 100 and the optical system inside the stage unit may be connected by an optical fiber or the like.

[0015] A first dichroic mirror 102 and a second dichroic mirror 103 functioning as an optical path splitter are disposed on the optical axis L1 of the objective lens 101. These dichroic mirrors split the optical path of the anterior eye observation system (optical axis L2), the optical path of the fundus photography system (optical axis L3), and the optical path of the OCT interference system (optical axis L5) into separate optical paths for each wavelength band.

[0016] <Anterior eye observation system> A lens 120, a diaphragm 121, a prism 122, a lens 123, and an image sensor 124 are arranged on an optical axis L2 in the reflection direction of the dichroic mirror 103. The image sensor 124 is a monochrome sensor having sensitivity in the infrared range. An anterior eye observation optical system for observing the anterior eye is configured by the optical members and the like arranged on the optical axis L2. The CMOS sensor 124 is connected to a control unit 300. Each pixel value acquired by the image sensor 124 is output to a monitor 301 via the control unit 300. In addition, an anterior eye observation light source 125 arranged near the objective lens 101 illuminates the anterior eye of the subject's eye E.

[0017] <Fundus photography system / fixation light> On the optical axis L3 in the transmission direction of the dichroic mirror 103, a perforated mirror 131, a photographing aperture 132, a focus lens 133, an imaging lens 134, a third dichroic mirror 135, and an image sensor 136 are arranged. An optical system for observing and photographing the fundus is configured. The perforated mirror 131 has an opening in the center. The focus lens 133 adjusts the focus by moving its position on the optical axis L3. The optical path on the optical axis L3 is branched by the third dichroic mirror 135 into an optical path leading to the image sensor 136 and an optical path leading to the fixation lamp 137 for each wavelength band. The image sensor 136 is a sensor that is sensitive to visible light and infrared light and is used for both moving image observation and still image capture. The fixation lamp 137 generates visible light to encourage the subject to fixate.

[0018] <Fundus illumination system> A corneal baffle 140, a relay lens 141, a focus index unit 142, a lens 143, and a ring slit 144 are arranged in this order on an optical axis L4 in the reflection direction of the perforated mirror 131. The corneal baffle 140 has a light-shielding point at the center. The ring slit 144 has a ring-shaped slit opening. Also arranged on the optical axis L4 are a crystalline lens baffle 145 as a light-shielding member having a light-shielding point, and a dichroic mirror 146 having the property of transmitting infrared light and reflecting visible light. The focus index unit 142 is movable along the optical axis L4 and can be inserted into and removed from the optical axis L4.

[0019] In the reflection direction of the dichroic mirror 146, a condenser lens 147 and a white LED light source 148 are arranged. The white LED light source 148 is an imaging light source in which a plurality of white LEDs that emit visible pulsed light are arranged. In the transmission direction of the dichroic mirror 146, a condenser lens 149 and an infrared LED light source 150 are arranged. The infrared LED light source 150 is an observation light source in which a plurality of infrared LEDs that emit infrared steady light are arranged. An illumination optical system for illuminating the fundus of the eye is configured by the objective lens 101, the dichroic mirror 146, the optical members therebetween, and the condenser lenses 147 and 149. Through this illumination optical system, the light of the white LED light source 148 or the infrared LED light source 150 illuminates the fundus of the eye to be examined.

[0020] <OCT optical system> On the optical axis L5 in the reflection direction of the dichroic mirror 102, a lens 151, a mirror 152, an OCT X scanner 153-1, an OCT Y scanner 153-2, and lenses 154 and 155 are arranged. The OCT X scanner 153-1 and the OCT Y scanner 153-2 are composed of, for example, dichroic mirrors and function as a scanning unit that scans the measurement light on the fundus Ef of the eye to be examined. Further, the OCT X scanner 153-1 and the OCT Y scanner 153-2 are arranged such that the vicinity of their central positions becomes the focal position of the lens 151. Also, the vicinity of this central position has an optical conjugate relationship with the position of the pupil of the eye to be examined E. With this configuration, the optical path with the scanning unit as the object point becomes substantially parallel between the objective lens 101 and the lens 151. Thereby, even when the fundus Ef is scanned with the measurement light by the OCT X scanner 153-1 and the OCT Y scanner 153-2, it is possible to make the incident angles of the measurement light incident on the dichroic mirror arranged therebetween the same. Note that the OCT X scanner 153-1 and the OCT Y scanner 153-2 scan the measurement light in the main scanning direction and the sub-scanning direction orthogonal thereto, respectively, but the scanning direction is not limited to this.

[0021] The measurement light source 157 is a light source that emits light for obtaining the measurement light to be incident on the measurement optical path.

[0022] In the present embodiment, the measurement light in the OCT optical system is emitted from the fiber end as a light source, and the fiber end has an optically conjugate relationship with the fundus Ef of the subject's eye E. The lens 154 is a lens for focus adjustment, and is driven in the optical axis direction indicated by the arrow in the figure by a motor (not shown). The focus adjustment of the measurement light is performed so that the measurement light emitted from the fiber end acting as the light source is imaged on the fundus Ef. The lens 154 functioning as a focus adjustment unit is disposed between the fiber end serving as the measurement light source and the OCTX scanner 153-1 and the OCTY scanner 153-2 functioning as the scanning unit. By the focus adjustment described above, the image of the measurement light emitted from the fiber end can be imaged on the fundus Ef of the subject's eye E, and the return light from the fundus Ef can be efficiently returned to the optical fiber 156-2.

[0023] In FIG. 1, the optical path between the OCTX scanner 153-1 and the OCTY scanner 153-2 is configured within the plane of the paper, but in reality, it is configured in a direction perpendicular to the plane of the paper.

[0024] Next, the configuration of the optical path from the measurement light source 157, the reference optical system, and the spectrometer 200 will be described. The measurement light source 157, the optical coupler 156, the optical fibers 156-1 to 156-4, the lens 158, the dispersion compensation glass 159, the reference mirror 160, and the spectrometer 200 constitute a Michelson interference system. The optical fibers 156-1 to 156-4 are single-mode optical fibers that are connected to the optical coupler 156 and integrated. The light emitted from the measurement light source 204 is guided to the optical coupler 156 via the optical fiber 156-1, and the light guided to the optical coupler 156 is split by the optical coupler 156 into the measurement light on the optical fiber 156-2 side and the reference light on the optical fiber 156-3 side. The measurement light is irradiated to the fundus Ef of the subject's eye E, which is the observation target, through the optical path of the OCT optical system described above, and reaches the optical coupler 156 again through the same optical path due to reflection and scattering by the retina.

[0025] On the other hand, the reference light reaches the reference mirror 160 via the optical fiber 156-3, the lens 158, and the dispersion compensation glass 159 inserted to adjust the dispersion of the measurement light and the reference light, and is reflected. The reference light reflected by the reference mirror 160 returns along the same optical path and reaches the optical coupler 156 again. The reference light and the measurement light (returned light) that reach the optical coupler 156 again are combined by the optical coupler 156. Here, when the optical path length of the measurement light and the optical path length of the reference light become almost the same, the combination causes interference between the respective lights. The reference mirror 160 is held so that its position can be adjusted in the optical axis direction indicated by the arrow in the figure by a motor and a driving mechanism (not shown). The driving mechanism is an example of a driving means for driving an optical member for changing the optical path length difference between the measurement light and the reference light, and is composed of a stepping motor, a feed screw, and a linear guide (not shown). The optical path length of the reference light can be adjusted to the optical path length of the measurement light that changes depending on the subject's eye E by using this motor or the like. The obtained interference light is guided to the spectrometer 200 via the optical fiber 156-4.

[0026] The spectrometer 200 includes a lens 201, a diffraction grating 202, a lens 203, and a line sensor 204. The interference light emitted from the optical fiber 156-4 becomes approximately parallel light via the lens 201, is then dispersed by the diffraction grating 202, and is imaged on the line sensor 204 by the lens 203. Each element in the line sensor 204 outputs a signal corresponding to the received light. The control unit 300 samples this signal at a predetermined timing using an image acquisition and generation unit 304 (described later), and performs predetermined signal processing to generate a tomographic image.

[0027] Next, the periphery of the measurement light source 157 will be described. In this embodiment, the measurement light source 157 uses an SLD (Super Luminescent Diode), which is a typical low-coherent light source. The central wavelength of the light emitted from the measurement light source 157 is 855 nm, and the wavelength bandwidth is about 100 nm. Here, the bandwidth is an important parameter because it affects the resolution in the optical axis direction of the tomographic image obtained. In addition, the type of light source selected here is an SLD, but it is sufficient to emit low-coherent light, and ASE (Amplified Spontaneous Emission) and the like can also be used. Considering that the central wavelength of the measurement light is to measure the eye, near-infrared light is appropriate. In addition, since the central wavelength affects the lateral resolution of the tomographic image obtained, it is desirable that the wavelength is as short as possible. For both reasons, light with a central wavelength of 855 nm is used in this embodiment.

[0028] In this embodiment, a Michelson interferometer is used as the interferometer, but a Mach-Zehnder interferometer may also be used. It is preferable to use a Mach-Zehnder interferometer when the light intensity difference between the measurement light and the reference light is large, and to use a Michelson interferometer when the light intensity difference is relatively small.

[0029] Further, the optical head unit 100 includes a head driving unit 170. The head driving unit 170 is an example of a driving means for driving the optical head unit 100, and is configured with a linear motion mechanism in three dimensions (X, Y, Z). The linear motion mechanism in each direction is configured with a stepping motor, a feed screw, and a linear motion guide (not shown), and is configured to be able to move the optical head unit 100 in three dimensions (X, Y, Z) relative to the subject's eye E. This allows alignment of the optical head unit 100 with respect to the subject's eye E. Note that the configuration of the driving unit is not limited to this. Here, the optical head unit 100 may be configured to be movable with respect to the stage unit 180 of FIG. 5, for example. In addition, a face receiving unit 181 for receiving the subject's face may be provided on the stage unit, and the face receiving unit 181 may be provided with a forehead receiving unit 182 for receiving the subject's forehead and a chin receiving unit 183 for receiving the subject's chin. The chin rest 183 is connected to the control unit 300, and is configured to be movable up and down relative to the face rest 181. This allows the height of the subject's eye E to be roughly adjusted relative to the optical head unit 100 by adjusting the elevation of the chin rest 183 according to the size of the subject's face, etc. At this time, for example, the optical head unit 100 can be moved relative to the stage unit to perform alignment with the subject's eye.

[0030] <Configuration of control unit 300> The control unit 300 is connected to each unit of the optical head unit 100 and the spectroscope 200. Specifically, the control unit 300 is connected to the infrared CCD 142 in the optical head unit 100, and is configured to be capable of generating an observation image of the anterior eye part Ea of the subject's eye E. The control unit 300 is also connected to the APD 115 in the optical head unit 100, and is configured to be capable of generating an observation image of the fundus Er of the subject's eye E. Furthermore, the control unit 300 is also connected to the head driving unit 170 in the optical head unit 100, and is configured to be capable of driving the optical head unit 100 three-dimensionally with respect to the subject's eye E.

[0031] On the other hand, the control unit 300 is also connected to the line sensor 204 of the spectrometer 200. This makes it possible to acquire a measurement signal that has been wavelength-resolved by the spectrometer 200, and further tomographic images of the subject's eye E can be generated based on the measurement signals.

[0032] The generated anterior ocular segment observation image, fundus observation image, and tomographic image of the subject's eye E can be displayed on a monitor 301 connected to the control unit 300.

[0033] <Alignment method for test eye E> Fig. 2 is a flowchart showing a control method of the fundus imaging apparatus according to the present embodiment. A method of automatic alignment of the subject's eye E using the optical coherence tomography imaging apparatus according to the present embodiment will be described with reference to the flowchart of Fig. 2. Prior to imaging, the examiner first makes the subject sit in front of the apparatus.

[0034] The control unit 300 starts automatic alignment upon receiving a switch operation (not shown) by the examiner. When the automatic alignment starts, in step S201, the control unit 300 functions as an anterior eye image acquisition unit, and periodically acquires an anterior eye image from the infrared CCD 142 and analyzes it. Specifically, the control unit 300 detects a pupil area in the input anterior eye image. The control unit 300 calculates a center position of the detected pupil area. The center position of the pupil area is an example of a predetermined position of the anterior eye to be examined. The control unit 300, as a deviation amount calculation means, calculates a displacement amount (positional deviation amount) between the center position of the detected pupil area and the center position of the anterior eye image. The optical coherence tomography imaging apparatus of this embodiment is configured so that the center of the anterior eye image and the optical axis of the objective lens 101-1 coincide with each other, and the displacement amount calculated in step S201 represents a positional deviation amount between the test eye E and the measurement optical axis. The above-mentioned displacement amount (positional deviation amount) is an example of the positional deviation amount between the eye E and the optical head unit 100.

[0035] In step S202, the control unit 300 determines whether the positional deviation amount calculated in step S201 is less than a predetermined value. If it is determined that the positional deviation amount is equal to or greater than the predetermined value (S202; No), the process proceeds to step S203. On the other hand, if it is determined that the positional deviation amount is less than the predetermined value (S202; Yes), the automatic alignment process ends.

[0036] If the process of step S203 is the first time, the control unit 300 proceeds to step S205.

[0037] In step S205, the control unit 300 instructs the head driving unit 170 to move the optical head unit 100 according to the positional deviation amount calculated in step S201 in order to reduce the positional deviation amount. The head driving unit 170 drives three motors (not shown) to move the position of the optical head unit 100 in three-dimensional (X, Y, Z) directions relative to the subject's eye E. More specifically, the control unit 300 instructs the number of rotations of each of the three motors (not shown). As a result, the position of the optical axis of the objective lens 101-1 mounted on the optical head unit 100 is corrected so as to approach the pupil center position of the anterior eye portion Ea of the subject's eye E. The control unit 300 is an example of a control means that controls the head driving unit 170 so as to reduce the first positional deviation amount between the subject's eye E and the optical head unit 100.

[0038] Then, the process returns to step S201. In step S201, the control unit 300 functions as an anterior-segment image acquisition unit, acquires a plurality of anterior-segment images of the subject's eye E at different times, and repeats the above process. In step S205, the control unit 300 functions as a tracking unit, and performs tracking of the subject's eye by the head driving unit 170 based on the plurality of anterior-segment images.

[0039] This series of automatic alignment operations allows the optical axis position of the objective lens 101-1 to coincide with the pupil center position of the anterior segment Ea of the subject's eye E, making it possible to capture a tomographic image of the subject's eye in a properly aligned state. Note that the positional relationship between the subject's eye E and the optical head unit 100 in this aligned state is an example of a predetermined positional relationship.

[0040] The process of step S201 is performed at a predetermined time interval, so depending on the relationship between the rotation speed of the motor and the magnitude of the positional deviation, the process may proceed to the next step S201 before the positional deviation becomes less than the predetermined value.

[0041] In step S202, if the positional deviation amount is repeatedly determined to be equal to or greater than the predetermined value (S202; No) even after the reduction of the positional deviation amount in step S205 is performed, it is considered that the movement of the subject's eye continues to be in a state in which the movement amount is greater than the predetermined value in S202 and the movement speed is faster than the movement speed of the optical head 100. The subject's posture that causes such a state may be such that the head is away from the forehead rest 182, causing the movement of the subject's eye to be unstable.

[0042] Therefore, if the process of step S203 is the second or subsequent time, the control unit 300 proceeds to step S204, detects the movement of the subject's eye, and, in some cases, notifies the examiner of information regarding the subject's posture.

[0043] <Method for detecting movement of examinee's eye E based on anterior eye observation image> FIG. 3 is a flowchart showing a control method for detecting the movement of the subject's eye E in step S204.

[0044] In step S301, the control unit 300 calculates the difference between the amount of misalignment (second misalignment amount) calculated in the immediately preceding process of S201 and the amount of misalignment (first misalignment amount) calculated in the process of S201 immediately before that. This difference is called the amount of change in misalignment. The second amount of misalignment is an amount of misalignment acquired at a time later than the time when the first amount of misalignment was acquired, and is an example of an amount of misalignment acquired under the control of the head driving unit 170, which is an example of a driving means. Note that "under the control of the head driving unit 170" does not strictly specify that the head driving unit 170 is actually being driven, but is a concept that also includes, for example, a timing when the head driving unit 170 is not being driven temporarily in preparation for the next drive.

[0045] In step S302, the control unit 300 calculates the reduction amount of the positional deviation of the subject's eye E in the immediately preceding process of S205. The reduction amount of the positional deviation is the movement amount of the optical head unit 100 in the immediately preceding process of S205. The movement amount of the optical head unit 100 can be calculated from the number of rotations of the motor and the pitch of the feed screw. Note that the method of calculating the movement amount of the optical head unit 100 is not limited to this. It may be calculated using an encoder or a displacement meter. In this case, the reduction amount of the positional deviation is an example of the amount by which the optical head unit 100 is driven between the time when the first positional deviation amount is acquired and the time when the second positional deviation amount is acquired.

[0046] In step S303, the control unit 300 calculates the difference between the amount of change in positional deviation calculated in S301 and the amount of reduction in positional deviation calculated in S302.

[0047] In step S304, the control unit 300 judges whether the difference between the amount of change in positional deviation calculated in S303 and the amount of reduction in positional deviation is less than a predetermined value. If it is judged to be equal to or greater than the predetermined value (S304; No), the process proceeds to step S305. On the other hand, if it is judged that the difference is less than the predetermined value (S304; Yes), the process proceeds to step S306.

[0048] If the subject's eye E does not move, the reduction amount of the positional shift is approximately the same as the change amount of the positional shift. On the other hand, if it is determined that the reduction amount of the positional shift and the change amount of the positional shift are different, it is found that the subject's eye E has moved over time, and the movement of the subject's eye E can be detected. If it is determined that the change amount of the positional shift is greater than the reduction amount of the positional shift, it is considered that the subject's forehead has moved away from the forehead support unit 182, for example, and the subject's eye has moved away from the optical head unit 100. On the other hand, if it is determined that the change amount of the positional shift is smaller than the reduction amount of the positional shift, it is considered that the subject's forehead, which was away from the forehead support unit 182, has moved, for example, and the subject's eye has moved closer to the optical head unit 100.

[0049] FIG. 6 is a schematic diagram showing the positional change over time of the optical head unit 100 and the eye E to be examined during automatic alignment according to this embodiment. At time t1, the position of the optical head unit 100 is Zhead(t1), and the position of the eye E to be examined is Zeye(t1). As described above, the first positional deviation amount at time t1 is calculated by the control unit 300 as ΔZwd(t1) (=Zhead(t1)−Zeye(t1)) based on the anterior eye observation image (processing of step S201). The shaded area in FIG. 6(b) indicates a certain range in which the positional deviation amount is less than a predetermined value. When the positional deviation amount ΔZwd(t1) is out of the range of the predetermined value, the control unit 300 drives the optical head unit 100 by a motor (not shown) to move it to the position Zeye(t1) in order to reduce the positional deviation amount ΔZwd(t1). The gradient Vz in FIG. 6(a) indicates the moving speed of the optical head unit 100, and is determined by, for example, the number of rotations of a motor (not shown) and the pitch of a feed screw. At time t, only ΔZwd(t) can be detected, and the position Zhead(t) of the optical head unit 1000 and the position Zeye(t) of the subject's eye E cannot be detected directly. At time t2, the control unit 300 calculates a second positional deviation amount ΔZwd(t2) (=Zhead(t2)-Zeye(t2)) between the optical head unit 1000 and the subject's eye E based on the anterior eye observation image. Furthermore, the control unit 300 calculates the reduction amount of the positional deviation (step S302). The reduction amount of the positional deviation is calculated as Zhead(t2)-Zhead(t1)=Vz×(t2-t1). 6, since the amount of change in positional deviation ΔZwd(t2)−ΔZwd(t1) is smaller than the amount of reduction in positional deviation Zhead(t2)−Zhead(t1), it is determined that the amount of reduction in positional deviation and the amount of change in positional deviation are different. As a result, it is found that the subject's eye has come closer to the optical head unit 100, for example, due to the forehead, which was away from the forehead support unit 182, moving.

[0050] In step S305, the control unit 300 notifies the monitor 301 that the movement of the subject's eye has been detected as a notification means. FIG. 7 shows an example of the notification content displayed on the monitor 301. The notification method may be to display a text message on the monitor 301. Examples of the text message to be displayed include "Please check the subject's posture" and "The head may be separated from the forehead support" as shown in FIG. 7(a). An illustration expressing the notification content may also be displayed. An example of the illustration to be displayed is one that calls attention to the posture of the subject and the state of the forehead support of the subject's head as shown in FIG. 7(b). In addition, when the anterior eye observation image is displayed on the monitor 301, the outer frame of the anterior eye observation image may be displayed in red as shown in FIG. 7(c). When the notification is displayed on the monitor 301, the control unit 300 continues the notification until the notification cancellation process is performed. The various notification methods described above are examples of methods for notifying information regarding the posture of the subject. Also, a different message may be notified as information regarding the posture of the subject depending on the magnitude relationship between the amount of change in positional displacement and the amount of reduction in positional displacement. After step S305, the control unit 300 ends the detection of the movement of the subject's eye, and proceeds to step S205.

[0051] In step S306, the control unit 300 determines whether or not a notification is being displayed on the monitor 301. If a notification is not being displayed (S306: No), the control unit 300 ends the detection of the movement of the subject's eye and proceeds to step S205. If a notification is being displayed (S306: Yes), the control unit 300 proceeds to step S307.

[0052] In step S307, the control unit 300 cancels the notification on the monitor 301. The control unit 300 erases the display of information on the posture of the subject from the monitor 301.

[0053] In this embodiment, the optical system is automatically aligned with respect to the subject's eye based on an anterior eye image captured by an infrared CCD, but this may be achieved using other methods. For example, an alignment indicator may be projected onto the anterior eye of the subject's eye, and the reflected light may be detected to perform automatic alignment in three dimensions (X, Y, Z).

[0054] <Anterior eye tracking during preparation for imaging> Next, the examiner performs preparation for photographing to obtain a tomographic image for photographing. Here, the preparation for photographing includes at least one of focus adjustment, polarization adjustment, light amount adjustment, and optical path length difference adjustment, for example. In addition, the preparation for photographing includes at least one of focus adjustment, polarization adjustment, light amount adjustment, and optical path length difference adjustment, for example. The examiner performs these preparations for photographing while viewing the anterior eye observation image, fundus observation image, and tomographic image displayed on the monitor 301, but if the alignment state of the subject's eye is not good, the preparation for photographing may take a long time.

[0055] Focus adjustment, polarization adjustment, etc. are generally performed while observing the brightness of the acquired image, but if the alignment state of the examinee's eye is poor, part of the light beam may be blocked by the pupil edge, resulting in a dark image. Also, the optical path length difference is generally adjusted while observing the position of the retina in the tomographic image, but if the alignment state of the examinee's eye is unstable, the position of the retina in the tomographic image may continue to move and become unstable.

[0056] Therefore, the optical coherence tomography imaging apparatus of this embodiment has an anterior eye tracking function that continues automatic alignment operation to prevent the alignment state of the subject's eye from deteriorating. By using the anterior eye tracking during preparation for imaging, the alignment state can be maintained as much as possible, and imaging preparation can be completed in a relatively short time.

[0057] When starting anterior eye tracking during preparation for imaging, it is desirable to continue anterior eye tracking as it is after the completion of the above-mentioned automatic alignment. When the automatic alignment is completed, the positional relationship between the optical axis position of the objective lens 101-1 and the anterior eye part Ea of the subject's eye E is appropriately adjusted. Therefore, by repeating the automatic alignment operation, the anterior eye tracking can maintain the positional relationship between the optical axis position of the objective lens 101-1 and the anterior eye part Ea of the subject's eye E at the time of completion of the first automatic alignment. In addition, the optical coherence tomography imaging apparatus of this embodiment continues to perform a movement detection operation of the subject's eye E to detect the movement of the subject's eye, and notifies the examiner of information regarding the subject's posture.

[0058] <Focus adjustment for fundus observation image> After the automatic alignment is completed, the control unit 300 adjusts the focus of the fundus observation image. The control unit 300 drives the focus lens 133 by a motor (not shown) using the focus index unit 142 as an index. After adjusting the focus of the fundus observation image, the control unit 300 acquires a tomographic image and adjusts the coherence gate.

[0059] <How to capture tomographic images> A method for capturing a tomographic image using the optical coherence tomographic imaging apparatus of this embodiment will be described. The examiner starts capturing images by operating a switch (not shown) on the control unit 300. Following an instruction to start capturing images, the control unit 300 periodically starts generating a tomographic image for recording based on the interference light output from the line sensor 204. Note that "for recording" is also expressed as "for capturing images."

[0060] Here, the interference light output from the line sensor 204 is a signal for each frequency dispersed by the diffraction grating 202. The control unit 300 performs FFT (Fast Fourier Transform) processing on the signal from the line sensor 204 to generate information on the depth direction at a certain point on the fundus Er. This generation of information on the depth direction at a certain point on the fundus Er is called an A-scan.

[0061] The measurement light irradiated onto the fundus Er can be arbitrarily scanned over the fundus Er by controlling the driving of at least one of the X scanner 153-1 and the Y scanner 153-2. The measurement light can be scanned over the subject's eye by the X scanner 153-1 and the Y scanner 153-2.

[0062] The control unit 300 generates a tomographic image at the arbitrary trajectory on the fundus Er by bundling a series of multiple A-scans acquired during one scan along this arbitrary trajectory into one two-dimensional image.

[0063] Furthermore, the control unit 300 repeats the above-mentioned scanning along the arbitrary trajectory a plurality of times by controlling the driving of at least one of the X scanner 153-1 and the Y scanner 153-2. When the operation along the same trajectory is performed a plurality of times, a plurality of tomographic images along the arbitrary trajectory on the fundus Er can be obtained. For example, the control unit 300 drives only the X scanner 153-1 to repeatedly perform scanning in the X direction, and generates a plurality of tomographic images on the same scanning line of the fundus Er. The control unit 300 can also simultaneously drive the X scanner 153-1 and the Y scanner 153-2 to repeatedly perform a circular operation, and generate a plurality of tomographic images on the same circle of the fundus Er. Then, the control unit 300 performs arithmetic averaging processing on the plurality of tomographic images to generate a single high-quality tomographic image, and displays it on the monitor 301.

[0064] On the other hand, the control unit 300 can also perform multiple scans while shifting the above-mentioned arbitrary trajectory in the XY direction by driving and controlling at least one of the X scanner 153-1 and the Y scanner 153-2. For example, multiple scans in the X direction are performed multiple times while shifting the scan in the Y direction at regular intervals to generate multiple tomographic images covering the entire rectangular area on the fundus Er. The control unit 300 then synthesizes the multiple tomographic images to generate three-dimensional information of the fundus Er and displays it on the monitor 301.

[0065] The scanning patterns by the X scanner 153-1 and the Y scanner 153-2 can be arbitrarily switched by pressing a scan pattern selection button (not shown).

[0066] The control unit 300 functions as a tomographic image acquisition unit, and acquires a tomographic image of the test eye E based on interference light generated by interfering between return light from the test eye E irradiated with measurement light and reference light corresponding to the measurement light.

[0067] <Automatic coherence gate adjustment> FIG. 4 is a flowchart showing a method for controlling the fundus imaging apparatus according to the present embodiment. With reference to the flowchart in FIG. 4, a method for automatic coherence gate adjustment of the subject's eye E using the optical coherence tomography imaging apparatus according to the present embodiment will be described. The coherence gate is, for example, a position corresponding to the optical path length of the reference light in the measurement optical path. The coherence gate adjustment can be performed by changing the optical path length difference between the measurement light and the reference light. At this time, the reference mirror 160 is an example of an optical member for changing the optical path length difference between the measurement light and the reference light, and is also an example of an optical member for changing the optical path length of the reference light. The optical member for changing the optical path length difference may be an optical member for changing the optical path length of the measurement light.

[0068] In step S401, the control unit 300 functions as a tomographic image acquisition unit, and periodically generates and analyzes an "adjustment" tomographic image based on the interference light output from the line sensor 204. Specifically, the control unit 300 detects the retina in the generated tomographic image. The control unit 300 calculates the detected retina position. As a deviation amount calculation means, the control unit 300 calculates the amount of displacement (Z deviation amount) between the detected retina position (Z direction) and a predetermined position (Z direction) of the tomographic image.

[0069] In step S402, the control unit 300 determines whether the Z deviation amount calculated in step S401 is less than a predetermined value. If it is determined that the Z deviation amount is equal to or greater than the predetermined value (S401; No), the process proceeds to step S403. On the other hand, if it is determined that the Z deviation amount is less than the predetermined value (S402; Yes), the automatic coherence gate adjustment is terminated.

[0070] If the process of step S403 is the first time, the control unit 300 proceeds to step S405.

[0071] In step S405, the control unit 300 instructs a driving mechanism (not shown) to move the reference mirror 160 according to the Z shift amount calculated in step 401 in order to reduce the Z shift amount. The driving mechanism drives a motor (not shown) to move the position of the reference mirror 160 in the optical axis direction. More specifically, the control unit 300 instructs the number of rotations of the motor (not shown). As a result, the reference mirror 160 moves, so that the optical path length of the reference system is corrected to approximately match the optical path length of the OCT optical system, and the retina of the subject's eye is displayed at a suitable position in the tomographic image. Note that the positional relationship between the subject's eye E and the OCT optical system in this state is an example of a predetermined positional relationship. At this time, the control unit 300 is an example of a control means that controls the driving mechanism so as to reduce a first positional shift amount between the subject's eye and an optical member (e.g., the reference mirror 160) for changing the optical path length difference between the measurement light and the reference light. For example, even during automatic coherence gate adjustment, a function (anterior eye tracking) of driving the optical head unit 100 using the anterior eye observation image may be executed, and a method of detecting the movement of the subject's eye E based on the anterior eye observation image may be executed. In this case, a positional deviation amount (Z deviation amount) between the subject's eye and an optical member (e.g., the reference mirror 160) for changing the optical path length difference between the measurement light and the reference light may be calculated as a third positional deviation amount. The driving mechanism may be an example of a second driving means. A positional deviation amount (Z deviation amount) acquired at a time later than the time when the third positional deviation amount was acquired may be calculated as a fourth positional deviation amount acquired under the control of the second driving means.

[0072] In step S402, if the Z deviation amount is repeatedly determined to be equal to or greater than the predetermined value (S402; No) even after the reduction of the Z deviation amount in step S405 is performed, it is considered that the movement of the subject's eye continues to be in a state in which the movement amount is greater than the predetermined value in S402 and the movement speed is faster than the movement speed of the reference mirror 160. The subject's posture that causes such a state may be that the head is away from the forehead rest 182, causing the movement of the subject's eye to be unstable.

[0073] Therefore, if the process of step S403 is the second or subsequent time, the control unit 300 proceeds to step S404. In step S404, the control unit 300 detects the movement of the subject's eye, and, in some cases, notifies the examiner of information regarding the posture of the subject.

[0074] <Method for detecting movement of examinee's eye E based on tomographic images> The control method for detecting the movement of the subject's eye E in step S404 can also be explained using the flowchart in FIG.

[0075] In step S301, the control unit 300 calculates the difference between the Z deviation amount (second positional deviation amount) calculated in the immediately preceding process of S201 and the Z deviation amount (first positional deviation amount) calculated in the process of S201 one step before that. This difference is called the change amount of Z deviation. Note that the second positional deviation amount is a positional deviation amount (Z deviation amount) acquired at a time later than the time when the first positional deviation amount was acquired, and is an example of a positional deviation amount acquired under the control of the drive mechanism, which is an example of a driving means. Note that "under the control of the drive mechanism" does not strictly specify that the drive mechanism is actually being driven, but is a concept that also includes, for example, a timing when the drive mechanism is not being driven temporarily in preparation for the next drive.

[0076] In step S302, the control unit 300 calculates the reduction amount of the Z-shift of the subject's eye E in the immediately preceding process of S405. The reduction amount of the Z-shift is the movement amount of the reference mirror 160 in the immediately preceding process of S405. The movement amount of the reference mirror 160 can be calculated from the number of rotations of the motor and the pitch of the feed screw. Note that the method of calculating the movement amount of the reference mirror 160 is not limited to this. It may be calculated using an encoder or a displacement meter. In this case, the reduction amount of the Z-shift is an example of the amount by which the reference mirror 160 is driven between the time when the first positional shift amount is acquired and the time when the second positional shift amount is acquired.

[0077] In step S303, the control unit 300 calculates the difference between the amount of change in Z shift calculated in S301 and the amount of reduction in Z shift calculated in S302.

[0078] In step S304, the control unit 300 judges whether the difference between the amount of change in Z shift calculated in S303 and the amount of reduction in Z shift is less than a predetermined value. If it is judged to be equal to or greater than the predetermined value (S304; No), the process proceeds to step S305. On the other hand, if it is judged that the amount of displacement is less than the predetermined value (S304; Yes), the process proceeds to step S306. If there is no movement of the subject's eye E, the amount of reduction in Z shift will be approximately the same as the amount of change in Z shift. On the other hand, if it is judged that the amount of reduction in Z shift is different from the change in Z shift, it is found that the subject's eye E has moved over time, and the movement of the subject's eye E can be detected.

[0079] In step S305, the control unit 300 notifies the monitor 301 that the movement of the subject's eye has been detected as a notification means. FIG. 7 shows an example of the notification content displayed on the monitor 301. The notification method may be to display a text message on the monitor 301. Examples of the text message to be displayed include "Please check the subject's posture" and "The head may be separated from the forehead support 182" as shown in FIG. 7(a). An illustration expressing the notification content may also be displayed. An example of the illustration to be displayed is one that calls attention to the posture of the subject and the state of the forehead support of the subject's head as shown in FIG. 7(b). In addition, when a tomographic image is displayed on the monitor 301, the outer frame of the tomographic image may be displayed in red as shown in FIG. 7(d). When a notification is displayed on the monitor 301, the control unit 300 continues the notification until a notification cancellation process is performed. The various notification methods described above are examples of methods for notifying information regarding the posture of the subject. After step S305, the control unit 300 ends the detection of the movement of the subject's eye, and proceeds to step S205.

[0080] In step S306, the control unit 300 determines whether or not a notification is being displayed on the monitor 301. If a notification is not being displayed (S306: No), the control unit 300 ends the detection of the movement of the subject's eye and proceeds to step S205. If a notification is being displayed (S306: Yes), the control unit 300 proceeds to step S307.

[0081] In step S307, the control unit 300 cancels the notification on the monitor 301. The control unit 300 erases the display of information on the posture of the subject from the monitor 301.

[0082] <Focus lens adjustment for tomographic images> After the automatic coherence gate adjustment is completed, the control unit 300 adjusts the focus of the tomographic image. The lens 154 is driven by a motor (not shown) so that the tomographic image is in a suitable state. After the above adjustments are completed, the control unit 300 captures a tomographic image for storage and a fundus observation image.

[0083] <Anterior eye tracking during shooting> When multiple scans are performed as described above to capture multiple tomographic images, the time required for the multiple scans is longer than that required for one scan. For example, the optical coherence tomography imaging apparatus according to this embodiment can set 696 scanning positions on the fundus Er by shifting the scan of 10 mm in the X direction by 0.014 mm in the Y direction. The optical coherence tomography imaging apparatus performs four operations at the same position for each of the 696 scanning positions to obtain a total of 2784 tomographic images (696 lines x 4 times), and can generate three-dimensional information of a range of 10 mm x 10 mm on the fundus Er. In the optical coherence tomography imaging apparatus according to this embodiment, one tomographic image is composed of a total of 696 A-scans, and the time required for one A-scan is 14.3 microseconds. Therefore, 696 x 14.3 microseconds = 10.0 milliseconds are required to obtain one tomographic image, and at least 10.0 milliseconds / image x 2784 images = 27.8 seconds are required to obtain all 128 tomographic images.

[0084] On the other hand, human eye movements are a type of involuntary movement, and it is difficult to completely suppress them, even if the subject is gazing at a fixation light, etc. In addition, the period in which these movements occur is significantly shorter than the aforementioned 27.8-second shooting period, and it is highly likely that these eye movements will occur many times during the acquisition of all 2,784 tomographic images.

[0085] Therefore, in order to prevent the alignment of the subject's eye from deteriorating even during imaging, the system is equipped with an anterior eye tracking function that continues automatic alignment operation. Also, in order to detect the movement of the subject's eye, the system continues to perform a movement detection operation of the subject's eye E and notifies the examiner of information regarding the subject's posture.

[0086] According to this embodiment, the movement of the subject's eye E is detected from a fundus observation image or a tomographic image, and information regarding the subject's posture is notified to the examiner, thereby reducing the possibility of imaging failure.

[0087] Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and variations are possible within the scope of the gist of the present invention described in the claims.

[0088] (Other embodiments) The present invention can also be realized by executing the following process. That is, the present invention can also be realized by supplying software (programs) that realize one or more functions of the various embodiments described above to a system or device via a network or a storage medium, and having a computer (or a CPU, MPU, or the like) of the system or device read and execute the programs. The computer has one or more processors or circuits, and may include multiple separate computers or a network of multiple separate processors or circuits to read and execute computer-executable instructions.

[0089] In this case, the processor or circuitry may include a central processing unit (CPU), a microprocessing unit (MPU), a graphics processing unit (GPU), an application specific integrated circuit (ASIC), or a field programmable gateway (FPGA). The processor or circuitry may also include a digital signal processor (DSP), a data flow processor (DFP), or a neural processing unit (NPU).

Claims

1. a driving means for driving an optical head unit including an optical system for imaging an eye to be examined of a subject so as to move the optical head unit; a control unit that controls the driving unit so as to reduce a first positional deviation amount between the eye to be examined and the optical head unit; a notification means for notifying information on the posture of the subject associated with the detection of a movement of the subject's eye when it is determined that a difference between the second positional deviation amount acquired under the control of the drive means and the first positional deviation amount is different from an amount by which the optical head unit is driven between the time when the first positional deviation amount was acquired and the time when the second positional deviation amount was acquired, the difference being a second positional deviation amount acquired at a time later than the time when the first positional deviation amount was acquired, and a difference between an amount by which the optical head unit is driven between the time when the first positional deviation amount was acquired and the time when the second positional deviation amount was acquired, is different; An ophthalmic apparatus comprising:

2. The ophthalmologic apparatus according to claim 1 , further comprising an acquisition unit that acquires the first positional deviation amount and the second positional deviation amount using information about a result of detecting an anterior segment of the subject's eye.

3. a second driving means for driving an optical member included in the optical system to move the optical member for changing the optical path length difference between the measurement light and the reference light; the control means controls the second driving means so as to reduce a third positional deviation amount between the eye to be examined and the optical member; and The ophthalmic device of claim 1 or 2, wherein the notification means notifies information regarding the posture of the subject associated with the detection of movement of the subject's eye when it is determined that a fourth positional deviation amount is acquired at a time later than the time when the third positional deviation amount is acquired, and that a difference between the fourth positional deviation amount acquired under the control of the second driving means and the third positional deviation amount is different from an amount by which the optical element is driven between the time when the third positional deviation amount was acquired and the time when the fourth positional deviation amount was acquired.

4. a driving means for driving an optical member included in an optical system for imaging an eye of a subject, the optical member being for changing an optical path length difference between the measurement light and the reference light, so as to move the optical member; a control unit that controls the driving unit so as to reduce a first positional deviation amount between the eye to be examined and the optical member; a notification means for notifying information on the posture of the subject associated with the detection of a movement of the subject's eye when it is determined that a difference between the second positional deviation amount acquired under the control of the driving means and the first positional deviation amount is different from an amount by which the optical member is driven between the time when the first positional deviation amount was acquired and the time when the second positional deviation amount was acquired, the difference being a second positional deviation amount acquired at a time later than the time when the first positional deviation amount was acquired, and a difference between an amount by which the optical member is driven between the time when the first positional deviation amount was acquired and the time when the second positional deviation amount was acquired, is different; An ophthalmic apparatus comprising:

5. The ophthalmic apparatus of claim 4, further comprising an acquisition means for acquiring the first positional shift amount and the second positional shift amount using information regarding a tomographic image of the test eye obtained using interference light between the return light from the test eye irradiated with the measurement light and the reference light.

6. A method for controlling an ophthalmic apparatus including a driving unit that drives an optical head unit including an optical system for imaging an eye to be examined of a subject, comprising the steps of: controlling the driving means so as to reduce a first positional deviation amount between the eye to be examined and the optical head unit; a step of notifying information on the posture of the subject associated with the detection of the movement of the subject's eye when it is determined that a difference between the second positional deviation amount acquired under the control of the driving means and the first positional deviation amount is different from an amount by which the optical head unit is driven between the time when the first positional deviation amount was acquired and the time when the second positional deviation amount was acquired, the difference being a second positional deviation amount acquired at a time later than the time when the first positional deviation amount was acquired, and a difference between an amount by which the optical head unit is driven between the time when the first positional deviation amount was acquired and the time when the second positional deviation amount was acquired, is different; A method for controlling an ophthalmic apparatus comprising:

7. 1. A method for controlling an ophthalmic apparatus including a driving unit that drives an optical member included in an optical system for imaging an eye of a subject, the optical member being for changing an optical path length difference between a measurement light and a reference light, the method comprising the steps of: controlling the driving means so as to reduce a first positional deviation amount between the eye to be examined and the optical member; a step of notifying information on the posture of the subject associated with the detection of the movement of the subject's eye when it is determined that a difference between the second positional deviation amount acquired under the control of the driving means and the first positional deviation amount is different from an amount by which the optical member is driven between the time when the first positional deviation amount was acquired and the time when the second positional deviation amount was acquired, the difference being a second positional deviation amount acquired at a time later than the time when the first positional deviation amount was acquired, and a difference between an amount by which the optical member is driven between the time when the first positional deviation amount was acquired and the time when the second positional deviation amount was acquired, is different; A method for controlling an ophthalmic apparatus comprising:

8. A program for causing a computer to execute the method for controlling an ophthalmologic apparatus according to claim 6 or 7.

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