JP2024108380A - Ophthalmic device and method for controlling the device - Google Patents

Abstract

To smoothly perform an alignment operation regardless of an individual difference of an eye to be examined.SOLUTION: An ophthalmologic device comprises: a first optical system including an objective lens facing an eye to be examined, and focus means, and for imaging the ocular fundus of the eye to be examined; a second optical system including an objective lens, and imaging the anterior eye part; alignment means for changing a relative position of the eye to be examined and the objective lens; and control means for performing first control for controlling the alignment means on the basis of the image captured by the first optical system, and second control for controlling the alignment means on the basis of the image captured by the second optical system. The first control is configured so that a position separated from the eye to be examined relative to a prescribed position in a drive range of the alignment means is set as an initial position, and the control means performs adjustment of the focus means while changing the relative position, and the second control is started after starting the first control.SELECTED DRAWING: Figure 6

Description

This disclosure relates to an ophthalmic device and a method for controlling the ophthalmic device.

In recent years, devices that use optical coherence tomography (OCT) to obtain cross-sectional images using interference from low-coherence light (OCT devices) have been put to practical use. These OCT devices can obtain cross-sectional images with a resolution on the order of the wavelength of the light incident on the object being inspected, so they can obtain high-resolution cross-sectional images of the object being inspected.

OCT devices are particularly useful as ophthalmic devices for obtaining tomographic images of the retina located at the fundus. Other useful ophthalmic devices include fundus cameras (devices for taking two-dimensional images of the fundus) and scanning laser ophthalmoscopes (SLOs). Refractometers (devices for measuring eye refractive power) and tonometers (tonometers) are also useful ophthalmic devices. Combined devices of these are also useful.

In such an ophthalmic device, it is important to precisely align (position) the imaging unit (mainly the measurement optical system) of the device to the test eye in order to photograph the test eye. Patent Document 1 describes an ophthalmic device that projects an alignment index onto the cornea of the test eye, divides the reflected light and captures it with an imaging element through an observation optical system, detects the relative position between the device and the test eye from the position of the divided alignment index image, and performs automatic alignment. In such a technology, in order to achieve the necessary alignment accuracy, an observation optical system that can observe the test eye with high resolution is required. Since the angle of view per pixel needs to be small to observe the test eye with high resolution, the observation range of the observation optical system in these devices is often limited to the test eye and its surroundings. Patent Document 2 also describes an ophthalmic device equipped with an optical system that observes a wide range using an external camera. Because the eye is observed from the side by an external camera along an axis different from the optical axis of the ophthalmic device, switching to an alignment means with the required alignment accuracy often does not occur smoothly because the image after switching is blurred or not within the observation range.

JP 2010-162424 A JP 2009-201981 A

However, when performing alignment using the high-precision observation optical system described above, for example, because there are individual differences in face size, when the subject places his or her face on the face support part of the device, the subject's eyes may fall outside the observation range of the observation optical system. Also, for example, when observing the subject's entire face and then switching to a high-precision observation system as necessary, problems may arise such as the switching not being smooth.

One embodiment of the present disclosure aims to perform alignment operations smoothly regardless of individual differences in the subject's eye.

An ophthalmic apparatus according to an embodiment of the present disclosure includes:
a first optical system for imaging a fundus of the subject's eye, the first optical system including an objective lens facing the subject's eye and a focusing device;
a second optical system for imaging the anterior segment of the eye, the second optical system including the objective lens;
an alignment means for changing a relative position between the eye and the objective lens;
a control unit that performs a first control for controlling the alignment unit based on an image captured by the first optical system, and a second control for controlling the alignment unit based on an image captured by the second optical system,
The first control sets a position farther from the subject's eye than a predetermined position within a driving range of the alignment means as an initial position,
The control means adjusts the focus means while changing the relative position,
The second control is started after the first control is started.

According to one embodiment of the present disclosure, alignment operations can be performed smoothly regardless of individual differences in the subject's eye.

1 illustrates an example of a schematic configuration of an OCT apparatus according to a first embodiment. 2 illustrates an example of a schematic optical configuration of an imaging unit according to the first embodiment. 13 shows an example of display of an anterior eye observation image, a frontal fundus image, and a tomographic image. FIG. 2 is a block diagram illustrating an example of a control unit according to the first embodiment. 1 shows several examples of anterior ocular viewing images. Shows the range of anterior eye observation images 1 is a flowchart showing a series of inspection processes. 2 illustrates an example of a schematic optical configuration of an imaging unit according to the first embodiment. 1 shows an example of a prism lens having an image splitting prism and an example of an anterior eye observation image obtained using the prism lens.

Below, exemplary embodiments for implementing the present disclosure will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, and relative positions of components described in the following embodiments are arbitrary and can be changed according to the configuration of the device to which the present disclosure is applied or various conditions. In addition, the same reference symbols are used between the drawings to indicate elements that are identical or functionally similar.

In the following, an image of the fundus refers to an image that includes information about the fundus. For example, images of the fundus include tomographic images and three-dimensional tomographic images, which are cross-sectional images of the fundus, frontal fundus images, which are two-dimensional images of the fundus, images including ring images, as well as En-Face images, OCTA frontal images, and OCTA tomographic images, which will be described later. In addition, fine anterior observation images are images acquired by an infrared CCD 112 for anterior observation, which will be described later, and wide anterior observation images are images acquired by a CCD 105 that is separate from the infrared CCD 112. As will be described later, the CCD 105 is used to acquire both wide anterior observation images and frontal fundus images, which are two-dimensional images of the fundus.

Example 1
Hereinafter, an ophthalmic imaging apparatus and a control method thereof will be described as an example of an ophthalmic apparatus and a control method thereof according to the present embodiment. The ophthalmic apparatus according to the present embodiment is an ophthalmic apparatus that photographs the fundus of a subject's eye, and is particularly used to obtain a front image of the fundus and a tomographic image, which are two-dimensional images of the fundus of the subject's eye. In this embodiment, an optical coherence tomography (OCT) apparatus that uses a trained model to align the apparatus with the subject's eye based on an anterior eye observation image will be described as an example of the ophthalmic apparatus.

(General configuration of the device)
The schematic configuration of an OCT device according to this embodiment will be described with reference to Fig. 1. Fig. 1 is a side view showing an example of the schematic configuration of an OCT device 1. The OCT device 1 is provided with an imaging unit 10, a control unit 20, a display unit 40, and an input unit 50. The imaging unit 10 is provided with an optical head unit 100, a stage unit 150, a base unit 190 incorporating a spectroscope described below, and a face receiving unit 160.

The optical head unit 100 includes a measurement optical system for irradiating the subject's eye with light and detecting the return light from the subject's eye, and capturing fine and wide anterior observation images, a frontal fundus image, and a tomographic image. The stage unit 150 is an example of a moving unit that can move the optical head unit 100 in the x, y, and z directions in the figure using a motor (not shown). The face support unit 160 is a chin rest that can fix the subject's chin and forehead to promote fixation of the subject's eye (test eye). The face support unit 160 also includes a driving member such as a motor (not shown), and the driving member functions as an example of a moving unit that can move the face support unit 160 in the y direction in the figure.

The control unit 20 is connected to the imaging unit 10, the display unit 40, and the input unit 50, and can control these. The control unit 20 can, for example, control the movement of the stage unit 150 and align the optical head unit 100 with the subject's eye. The control unit 20 can also generate anterior eye observation images, frontal fundus images, tomographic images, etc., based on the data acquired by the imaging unit 10.

The control unit 20 can be configured using a general computer including a processor and memory, but may also be configured as a computer dedicated to the OCT device 1. The control unit 20 may be not only a separate (external) computer to which the imaging unit 10 is communicatively connected, but also a built-in (internal) computer of the imaging unit 10. The control unit 20 may also be, for example, a personal computer, such as a desktop PC, a notebook PC, or a tablet PC (portable information terminal).

The display unit 40 is composed of any monitor, and displays various information such as subject information, various images, a mouse cursor in accordance with the operation of the input unit 50, etc., according to the control of the control unit 20. The input unit 50 is an input device that issues instructions to the control unit 20, and specifically includes a keyboard and a mouse. Note that the display unit 40 may be a touch panel display, in which case the display unit 40 also serves as the input unit 50.

In this embodiment, the image capture unit 10, the control unit 20, the display unit 40, and the input unit 50 are configured separately, but some or all of these may be configured as an integrated unit. In addition, the control unit 20 may be connected to other image capture devices, storage devices, etc. (not shown).

(Configuration of the measurement optical system and the spectrometer)
Next, an example of the configuration of the measurement optical system and the spectrometer of this embodiment will be described with reference to Fig. 2. Fig. 2 shows an example of a schematic optical configuration of the photographing unit 10. First, the internal configuration of the optical head unit 100 will be described.

In the optical head unit 100, an objective lens 101-1 is arranged facing the subject's eye E, and a first dichroic mirror 102 is arranged on its optical axis as a first optical path separation means. The optical path from the objective lens 101-1 is branched by the first dichroic mirror 102 into an optical path leading to the measurement optical path L1 of the OCT optical system and the optical path L2 for fundus observation/wide anterior eye observation and fixation lamp, and a fine anterior eye observation optical path L3 for each wavelength band of light. In addition, a second dichroic mirror 103 is arranged in the reflection direction of the first dichroic mirror 102 as a second optical path separation means. The optical path in the reflection direction of the first dichroic mirror 102 is branched by the second dichroic mirror 103 into the measurement optical path L1 of the OCT optical system and the optical path L2 for fundus observation/wide anterior eye observation and fixation lamp for each wavelength band of light. The optical path in which the objective lens 101-1 is provided and the optical system configured by the optical path L2 are an example of a first optical system that images the fundus of the subject's eye E. That is, the first optical system includes the objective lens 101-1 facing the subject's eye E and a focusing means described below. The optical path in which the objective lens 101-1 is provided and the optical system configured by the optical path L3 are an example of a second optical system that images the anterior segment. That is, the second optical system includes the objective lens 101-1. In this case, the first optical system and the second optical system share the optical path in which the objective lens 101-1 is provided.

In the configuration according to this embodiment, the fine anterior eye observation optical path L3 is arranged in the transmission direction of the first dichroic mirror 102, and the measurement optical path L1 of the OCT optical system and the optical path L2 for fundus observation/wide anterior eye observation and fixation lamp are arranged in the reflection direction. In addition, the measurement optical path L1 of the OCT optical system is arranged in the transmission direction of the second dichroic mirror 103, and the optical path L2 for fundus observation/wide anterior eye observation and fixation lamp are arranged in the reflection direction. However, the optical paths arranged in the transmission direction and reflection direction of each dichroic mirror may be reversed.

In the optical path L2 for fundus observation/wide anterior eye observation and internal fixation light, lenses 101-2, 108, 107, and a third dichroic mirror 104 are arranged in this order from the second dichroic mirror 103. The optical path L2 for fundus observation/wide anterior eye observation and internal fixation light is branched by the third dichroic mirror 104, which is a third optical path separation means, into an optical path to a CCD 105 for fundus observation/wide anterior eye observation and an optical path to a fixation light 106 for each wavelength band of light. In this embodiment, the fixation light 106 is arranged in the transmission direction of the third dichroic mirror 104, and the CCD 105 for fundus observation/wide anterior eye observation is arranged in the reflection direction. Note that the CCD 105 may be arranged in the transmission direction of the third dichroic mirror 104, and the fixation light 106 may be arranged in the reflection direction.

Lens 107 is a focus lens, and is used for fundus observation and wide anterior eye observation, and for adjusting the focus of optical path L2 for the internal fixation lamp. Lens 107 can be driven in the optical axis direction by a motor (not shown) or the like controlled by control unit 20. The focus lens is an example of a focusing means, and may be composed of, for example, a reflecting member.

The CCD 105 has sensitivity to the wavelength of light emitted from an illumination light source for fundus observation (not shown), specifically, around 780 nm. On the other hand, the fixation lamp 106 emits visible light to encourage the subject to fixate. Based on the signal output from the CCD 105, the control unit 20 can generate a frontal fundus image, which is a two-dimensional image of the fundus of the subject's eye E.

The fine anterior eye observation optical path L3 is provided with, in order from the first dichroic mirror 102, lenses 109, 110, and 111, and an infrared CCD 112 for anterior eye observation. In addition, two anterior eye observation light sources 122 are provided on either side of the objective lens 101-1 in the x direction of the figure.

The infrared CCD 112 is an example of an observation unit that captures the front of the optical head unit 100, in other words, the direction in which the subject is positioned, via the lenses 109, 110, and 111. The infrared CCD 112 captures the anterior part of the subject's eye, particularly when the subject's eye is in an appropriate position relative to the optical head unit 100. The infrared CCD 112 has sensitivity to the wavelength of the anterior eye observation light source 122, specifically around 970 nm. The control unit 20 generates an image in front of the optical head unit 100, including an anterior eye observation image, based on the signal output from the infrared CCD 112. The anterior eye observation light source 122 can project an index onto the subject's eye so that a corneal bright spot appears in the anterior eye observation image.

The optical components that constitute the OCT optical system are arranged in the measurement optical path L1 of the OCT optical system, and the OCT optical system is configured to capture a tomographic image of the fundus of the test eye E. More specifically, the OCT optical system is used to obtain an interference signal for forming a tomographic image.

In the measurement light path L1, in order from the second dichroic mirror 103, there are arranged a lens 101-3, a mirror 113, an X scanner 114-1 and a Y scanner 114-2 for scanning the light on the fundus of the test eye E, and lenses 115 and 116.

The X scanner 114-1 and the Y scanner 114-2 are an example of a scanning means for the measurement light of OCT, and are arranged to scan the measurement light on the fundus of the subject eye E. The X scanner 114-1 is used to scan the measurement light in the x direction, and the Y scanner 114-2 is used to scan the measurement light in the y direction. In this embodiment, the X scanner 114-1 and the Y scanner 114-2 are configured with a galvanometer mirror, but the X scanner 114-1 and the Y scanner 114-2 may be configured with any deflection means according to the desired configuration. In addition, the scanning means for the measurement light may be configured with a deflection means that can deflect light in a two-dimensional direction with a single mirror such as a MEMS mirror.

The lens 115 is a focus lens, and is used to adjust the focus of the light from the light source 118, which is emitted from the optical fiber 117-2 connected to the optical coupler 117, on the fundus. The lens 115 can be driven in the optical axis direction by a motor (not shown) or the like controlled by the control unit 20. This focus adjustment causes the return light from the fundus to be imaged as a spot on the tip of the optical fiber 117-2 and to be incident thereon.

Next, the configuration of the optical path from the light source 118, the reference optical system, and the spectrometer will be described. The light source 118 is an SLD (Super Luminescent Diode), which is a typical low-coherent light source. In this embodiment, an SLD with a central wavelength of 855 nm and a wavelength bandwidth of approximately 100 nm was used as the light source 118. Note that, although an SLD was selected as the light source 118 in this embodiment, it is sufficient to emit low-coherent light, and an ASE (Amplified Spontaneous Emission) or the like can also be used.

The light source 118 is connected to the optical coupler 117 via optical fiber 117-1. Single-mode optical fibers 117-1 to 117-4 are connected and integrated to the optical coupler 117. The light emitted from the light source 118 is split into measurement light and reference light by the optical coupler 117, and the measurement light is guided to the measurement optical path L1 via optical fiber 117-2, and the reference light is guided to the reference optical system via optical fiber 117-3. The measurement light is irradiated onto the fundus of the subject's eye E via the measurement optical path L1, and reaches the optical coupler 117 via the same optical path due to reflection and scattering by the retina.

On the other hand, the reference light split by the optical coupler 117 and guided by the optical fiber 117-3 is emitted to the reference optical system. In the reference optical system, a lens 121, dispersion compensation glass 120, and a mirror 119 (reference mirror) are arranged in this order from the emission end of the optical fiber 117-3.

The reference light emitted from the output end of optical fiber 117-3 reaches mirror 119 via lens 121 and dispersion compensation glass 120, where it is reflected. Dispersion compensation glass 120 is inserted in the optical path to match the dispersion of the measurement light and reference light. The reference light reflected by mirror 119 returns along the same optical path and reaches optical coupler 117. Mirror 119 can be driven in the optical axis direction indicated by the arrow in the figure by a motor (not shown) or the like controlled by control unit 20.

The measurement light returning from the subject's eye E and the reference light reflected from the mirror 119 are combined by the optical coupler 117 to become interference light. Here, interference occurs when the optical path length of the measurement light and the optical path length of the reference light are approximately the same. Therefore, by moving the mirror 119 in the optical axis direction using the motor or the like described above and matching the optical path length of the reference light to the optical path length of the measurement light, which changes depending on the subject's eye E, interference light from the measurement light and the reference light can be generated. The interference light is guided to the spectroscope 180 via optical fiber 117-4.

Spectrometer 180 is an example of a detection unit that detects interference light. Spectrometer 180 is provided with lenses 181 and 183, a diffraction grating 182, and a line sensor 184. The interference light emitted from optical fiber 117-4 becomes approximately parallel light via lens 181, is then dispersed by diffraction grating 182, and is imaged on line sensor 184 by lens 183.

Information about the luminance distribution in the signal acquired by the line sensor 184, which is a detector, is output to the control unit 20 as an interference signal. The control unit 20 can generate a tomographic image based on the interference signal output from the line sensor 184.

Here, obtaining tomographic information from one point on the subject's eye E is called an A-scan. Also, the luminance distribution on the line sensor 184 obtained at a certain position in the x-direction is subjected to a fast Fourier transform (FFT) and the obtained linear luminance distribution is converted into density or color information, which is called an A-scan image. Furthermore, a two-dimensional image in which multiple A-scan images are arranged is called a B-scan image (tomographic image).

In addition, after capturing multiple A-scan images to construct one B-scan image, multiple B-scan images can be obtained by moving the scan position in the y direction and scanning again in the x direction. A three-dimensional tomographic image can be constructed by arranging multiple B-scan images in the y direction. The control unit 20 can display multiple B-scan images or a three-dimensional tomographic image constructed from multiple B-scan images on the display unit 40, allowing the examiner to use these images to diagnose the subject's eye E.

In this embodiment, a Michelson interferometer is formed by the measurement optical system, the reference optical system, and the spectrometer optical system, which are made up of the various components arranged in the measurement optical path L1. Alternatively, a Mach-Zehnder interferometer may be used as the interferometer.

Figure 3 shows an example of an anterior eye observation image 300, a frontal fundus image 301, and a B-scan image 302, which is a tomographic image, displayed on the display unit 40. The anterior eye observation image 300 is an image generated by processing the output of the infrared CCD 112, the frontal fundus image 301 is an image generated by processing the output of the CCD 105, and the B-scan image 302 is an image generated by processing the output of the line sensor 184 as described above.

(Configuration of the control unit)
Next, the configuration of the control unit 20 will be described with reference to Fig. 4. Fig. 4 is a block diagram showing an example of the configuration of the control unit 20. The control unit 20 includes an acquisition unit 21, a drive control unit 22, an image generation unit 23, a positional deviation estimation unit 24, and a storage unit 25.

The acquisition unit 21 can acquire various signals output from the CCD 105, the infrared CCD 112, and the line sensor 184. The acquisition unit 21 can also acquire instructions from the operator via the input unit 50. Furthermore, the acquisition unit 21 can acquire various information such as subject information stored in the memory unit 25, various images such as tomographic images, and various images generated by the image generation unit 23.

The drive control unit 22 controls the driving of various components in the imaging unit 10. Specifically, the drive control unit 22 is an example of a movement control means that can control the driving of, for example, the stage unit 150, the face receiving unit 160, the lens 107, the X scanner 114-1, the Y scanner 114-2, the lens 115, and the mirror 119. The drive control unit 22 can also control the turning on and off of the anterior eye observation light source 122, the fundus illumination light source (not shown), the fixation lamp 106, and the light source 118. Note that when driving the stage unit 150, the drive control unit 22 can also function as, for example, the function of the alignment unit 24 described below. In this case, the alignment unit 24 is unnecessary because it can be replaced by the drive control unit 24.

The image generating unit 23 can generate a frontal fundus image based on the output signal of the CCD 105 acquired by the acquiring unit 21, generate an anterior eye observation image based on the output signal of the infrared CCD 112, and generate a tomographic image based on the interference signal output from the line sensor 184. Note that any known method may be used to generate an image for an ophthalmologist, such as a tomographic image or a frontal fundus image, from ophthalmic information, such as data on the tomography of the subject's eye E and data on the fundus.

The alignment unit 24 controls the stage unit 150 based on the image generated by the image generation unit 23 to change the position of the optical head unit 100 relative to the position of the subject's eye E and perform alignment. Here, the stage unit 150 is an example of an alignment means that changes the relative position between the subject's eye and the objective lens. The alignment means may be configured to move the face receiving unit 160, for example. The alignment unit 24 is also an example of a control means that performs a first control that controls the alignment means based on an image captured by the first optical system. The alignment unit 24 is also an example of a control means that performs a second control that controls the alignment means based on an image captured by the second optical system. In this embodiment, the alignment of the optical head unit 100 in the xyz directions relative to the subject's eye E is controlled based on the wide anterior observation image acquired by the CCD 105 and the fine anterior observation image acquired by the infrared CCD 112. Details of the control of alignment using the wide anterior observation image and the fine anterior observation image will be described later. Here, the wide anterior observation image is an example of an image captured by the first optical system. The fine anterior observation image is an example of an image captured by the second optical system. Alignment control using the fine anterior observation image is an example of the first control. Alignment control using the wide anterior observation image is an example of the second control.

The storage unit 25 can store various types of information and images that have been generated. The storage unit 25 can also store identification information of the subject, etc. Furthermore, the storage unit 25 can store programs for imaging, etc.

Each component of the control unit 20 other than the memory unit 25 may be configured with a software module executed by a processor such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit). The processor may be, for example, a GPU (Graphical Processing Unit) or an FPGA (Field-Programmable Gate Array). Each component may be configured with a circuit that performs a specific function, such as an ASIC. The memory unit 25 may be configured with any storage medium, such as an optical disk such as a hard disk, or a memory.

(Image for anterior eye observation)
Two images for anterior eye observation are acquired: an image for fine anterior eye observation acquired by the infrared CCD 112 and an image for wide anterior eye observation acquired by the CCD 105 .

Figures 5(a) to 5(f) show images taken by both devices for anterior eye observation.

The fine anterior eye observation image acquired by the infrared CCD 112 is acquired using an optical system designed to reduce the angle of view per pixel so that the alignment between the main body head unit 100 and the subject's eye E can be performed with high precision. This results in a narrow observation range. In addition, in order to perform alignment in the Z direction with high precision, for example, a method is provided in which light from the anterior eye observation light source 122 is reflected by the cornea and the position of the corneal bright spot, which is a regular reflection of the reflected light, is detected.

Figure 5 (a) shows an example of a fine anterior eye observation image when the positional relationship between the optical head unit 100 and the center of the pupil of the subject's eye E is aligned. In this example, the pupil of the subject's eye E is located approximately in the center of the image. In addition, corneal bright spots, which are the regular reflection of light from the anterior eye observation light source 122 by the cornea, are located on both sides of the pupil.

Figure 5(b) shows an example when the optical head unit 100 and the subject's eye E are separated in the z direction. In this example, the image is blurred because the subject's eye E is away from the focal plane of the infrared CCD 112. Also, in the image shown in Figure 5(b), the subject's eye E is farther from the optical head unit 100, so it appears smaller than the subject's eye E in the image shown in Figure 5(a). Also, in the image shown in Figure 5(b), the angle of specular reflection by the cornea of the light from the anterior eye observation light source 122 is different, so the spacing between corneal bright spots is narrower than the spacing between corneal bright spots in the image shown in Figure 5(a).

Figure 5(c) shows an example when the optical head unit 100 and the test eye E are further apart in the z direction. Because the test eye E is farther away from the optical head unit 100, the test eye E appears even smaller than the test eye E in the image shown in Figure 5(b). The corneal bright spot cannot be observed.

On the other hand, wide anterior eye observation images are acquired using an optical system designed to increase the angle of view per pixel so that the subject's eye E can be observed over a wide range. Furthermore, a focus mechanism is provided within the optical system to prevent the image from becoming blurred when the main body head unit 100 and the subject's eye E move significantly apart or close to each other in the Z direction. Wide anterior eye observation images are acquired by the CCD 105.

The optical path L2 for fundus observation, wide anterior eye observation, and fixation lamp is equipped with a focus mechanism using a lens 107, and during wide anterior eye observation, the lens position is changed according to the distance so that the subject's eye E can be detected even if the Z-directional distance between the main body head unit 100 and the subject's eye E changes. On the other hand, during fundus observation, a specified Z-directional distance (working distance) between the main body head unit 100 and the subject's eye E is maintained, and the lens position is changed according to the diopter of the subject's eye E to observe the fundus of the subject's eye E. By changing the focus according to the Z-directional distance in this way, it is possible to constantly perform wide anterior eye observation while also performing fundus observation.

Figure 5(d) shows an example of a wide anterior eye observation image in which the positional relationship between the optical head unit 100 and the center of the pupil of the test eye E is aligned. In this example, the pupil of the test eye E is located approximately in the center of the image.

Figure 5(e) shows an example when the optical head unit 100 and the test eye E are separated in the Z direction and also misaligned in the X and Y directions. By driving the lens 107, the test eye E is in focus even when separated in the Z direction. Also, in the image shown in Figure 5(e), because the test eye E is farther away from the optical head unit 100, the test eye E appears smaller than the test eye E in the image shown in Figure 5(d).

Figure 5(f) shows an example when the optical head unit 100 and the subject's eye E are approaching each other in the Z direction. Because the subject's eye E is closer to the optical head unit 100, the subject's eye E appears larger than the subject's eye E in the image shown in Figure 5(a). Also, because the subject's eye E is outside the focusing range of the image acquired by the CCD 105, it appears blurry.

Next, referring to FIG. 6, the positional relationship when performing alignment using both fine anterior observation and wide anterior observation will be described. FIG. 6(a) to FIG. 6(d) are diagrams showing the positional relationship between the range of each anterior observation and the objective lens 101-1, and the position of the subject eye E.

Figure 6 (a) shows the objective lens 101-1, the wide anterior observation range, and the fine anterior observation range. In addition, (a) to (f) are described below to correspond to the anterior observation image in Figure 5. The wide anterior observation range has an observation range in a direction away from the objective lens 101-1, and has a wide range in each of the X, Y, and Z directions. In contrast, the fine anterior observation range has an observation range in a direction closer to the objective lens 101-1, and is narrower in each of the X, Y, and Z directions compared to the wide anterior observation range. It is configured to enable high-precision alignment by observing the narrow range in detail. In addition, an overlapping area is provided between the two, and the area is used as a switching area, so that alignment can be performed using both anterior observations.

Next, the correspondence between FIG. 6(a) and FIG. 5 will be explained. In correspondence with fine anterior observation, the position where a clear observation image is confirmed in FIG. 5(a) is a position included in the fine anterior observation range. The position shown in FIG. 5(b) corresponds to the boundary of the fine anterior observation range because the position of the corneal bright spot can be confirmed even though the image is blurred. The position shown in FIG. 5(c) corresponds to a position that is blurred and furthermore the position of the corneal bright spot cannot be confirmed, is outside the fine anterior observation range, and is far from the objective lens 101-1.

In correspondence with wide anterior eye observation, the position shown in FIG. 5(e) corresponds to a position far from the objective lens 101-1 within the wide observation range, since a wide position can be observed. The position shown in FIG. 5(d) is closer to the objective lens 101-1 than FIG. 5(e), and is also within the wide observation range. Finally, the position shown in FIG. 5(f) is a position close to the objective lens 101-1, corresponds to outside the range of wide anterior eye observation, and is outside the wide range, so it is the area where alignment is performed in fine anterior eye observation. The position where the wide anterior eye observation range is zero is the pupil position of the optical system, and fundus observation and OCT photography are basically performed by matching the pupil of the subject eye E to the pupil position of this optical system. The wide anterior eye observation range is located farther than this pupil position.

In FIG. 6(b), the subject's eye E is included in the wide anterior ocular observation range, but is positioned offset in the XY direction relative to the objective lens 101-1. Since it has wide anterior ocular observation, it is possible to detect the subject's eye E. XYZ alignment is performed based on the detection results.

Figure 6 (c) shows a state in which the subject eye E is included in the wide anterior observation range and is on the optical axis of the objective lens 101-1. It is also in a position included in the fine anterior observation range, and switching is performed from wide anterior observation to fine anterior observation.

Figure 6 (d) shows the state in which the subject eye E is included in the fine anterior eye observation range and is positioned at a predetermined position in the XYZ directions, and alignment is complete.

(Flow of capturing tomographic images)
Next, a flow of image capture for the inspection according to this embodiment will be described in order of steps with reference to Fig. 7. Fig. 7 is a flow chart showing a series of processes for the inspection according to this embodiment.

First, in step S701, the examiner inputs subject information to the control unit 20 using the input unit 50. Here, the test is started by this operation.

Next, in step S702, the drive control unit 22 moves the face receiving unit 160 and the optical head unit 100 to a predetermined position. It is desirable for the predetermined position to be a position that allows wide anterior eye observation to observe a wider range so that the position of the subject eye can be detected even if there are individual differences in the subject eye, and the main body head unit 100 starts from a position that is the furthest away from the subject eye E. However, if the position information of the main body head unit from the previous examination is stored in the memory unit 25, such as at the time of a re-examination, the information may be read out to shorten the examination time. At this time, the initial position of the first control may be set to a position farther away from the subject eye than the predetermined position within the driving range of the alignment means.

Next, in step S703, the lens 107 is positioned at a predetermined position and XY adjustment is performed. By driving the optical head unit 100 in the XY directions, the subject's eye E is displayed approximately at the center of the wide anterior eye observation image. As will be described later, if focus cannot be obtained due to individual variation in the subject's eye E, control loops to step S704. At this time, the focus means can be adjusted while changing the relative position between the subject's eye and the objective lens.

Next, in step S704, the position of the lens 107 is set to a predetermined position, and the optical head is moved closer. Specifically, taking into consideration individual variability in the subject's eye E, the position of the lens 107 is fixed, and the main body head unit 100 is moved closer to a position where wide anterior eye observation can be clearly performed while the lens 107 is focused in front of the subject's eye E.

For example, assuming an average subject eye E with the main body head unit at its furthest position, it is considered that the focus is achieved when the lens 107 is positioned at a position equivalent to +15 diopters.

In one case, when the subject's eye E is closer than the average position, +15 diopters will not focus, and it will be necessary to either set a larger diopter or move the head of the main unit farther away from the subject's eye E. Since the latter is not possible, the former is adopted, and a setting of, for example, +18 diopters will be used to obtain a clear, focused image.

In the other case, if the position is farther than the average position mentioned above, it is necessary to set a smaller diopter or move the head unit closer to the subject's eye E. In this case, both are possible, but considering both the case where the subject's eye E is close and the case where it is far away, it is desirable to obtain a clear wide anterior eye observation image while moving the head unit closer with the diopter set to +18, for example. This operation allows alignment to be performed taking into account the variation between the two.

Variations in the optical system are taken into consideration by checking and adjusting the relationship between the position of the lens 107 and the diopter in advance, and for a diopter setting such as +18, the drive control unit 22 operates the lens 107 to a specified position based on the above relationship stored in the main body storage unit 25.

Next, in step S705, by adjusting the XY axis and moving the main body head unit closer, it is determined whether the test eye E is clear and located approximately at the center of the wide anterior eye observation image. If it is not determined to be clear based on the threshold value, or if it is not determined to be approximately at the center of the image, steps S703 and S704 are performed again. If both are determined to be good based on the threshold value, the process proceeds to the next step S706. If the test eye E is outside the driving range of the main body head unit 100 and the image of the test eye E cannot be detected, the chin rest (not shown) of the face support unit 160 is adjusted to bring it within the driving range.

Whether an image is clear or not can be judged, for example, by judging the contrast of the image or by performing a Fourier transform to judge whether high frequency components can be detected, but this is not limited to this and includes judging the focus. In addition, whether an image is at the center position can be judged by detecting the center position of the pupil of the subject's eye E through processing such as binarization, and judging whether the detected pupil center and the center of the image sensor are within a certain area.

Next, in step S706, the main body head unit 100 is brought even closer to the subject's eye E. In many cases, alignment in the XY directions is not necessary if the subject's eye E is fixed, but the main body head unit 100 may be brought closer while performing XY tracking in response to the movement of the subject's eye E.

As described above, when the main body head unit 100 is brought even closer to the subject's eye E, the image of the subject's eye E in wide anterior observation goes out of focus, making it difficult to obtain a clear image. Therefore, when approaching, the position of the lens 107 is moved and drive control is performed so that a clear image can be continuously obtained. The lens drive control may be performed using a method that is preset for the drive amount of the main body head, or the focus state of the subject's eye E may be detected and the focus may be automatically adjusted to continuously obtain a clear image.

As an example of a method for driving the lens 107 using a preset method, the position of the lens 107 is controlled by using the difference in the position of the main body head from the reference position as a parameter, with the position of the main body head completed up to S705 as the reference. Since the difference in the position of the main body head and the diopter corresponding to the position of the lens 107 are inversely proportional to each other, it is desirable to control the position of the lens 107 in an inversely proportional manner. As the main body head is brought closer, the diopter is increased in the + direction. If the drive amount of the main body head when brought closer is ΔZ, then driving with a relationship of 1000/ΔZ with respect to the diopter of the lens 107 is an example of driving. By setting the diopter corresponding to the initial position of the lens 107 (+18 diopter in an example of steps S703 and S704) as the initial position and driving the lens 107 according to the movement amount of the main body head position, a wide anterior eye observation image that is always clear can be obtained.

As another example, since there is a certain range for the main body head position where a clear image can be obtained, the lens 107 is not driven all the time, but is driven in stages. The basic control is the inverse proportional relationship described above, but it is also possible to set a range in advance within which the lens 107 will not be driven in relation to the drive of the main body head, and drive the lens 107 when it goes outside the set range. It is also the same if a range is set for the diopter of the lens 107.

Depending on the movement of the test eye E in the Z direction, the lens 107 may be fine-tuned or the optical head may be driven in the opposite direction.

Next, in step S707, the alignment detection means is switched from wide anterior observation to fine anterior observation. When the subject's eye E reaches the switching region shown in FIG. 6A, the alignment detection means is switched from wide-range alignment to high-precision alignment. At this time, the second control may be started after the first control is started.

As an example, to determine whether the subject's eye E is within the switching region, the drive amount of the optical head position is used as the criterion for determination, and when the drive amount reaches a certain amount, the alignment detection means is switched. Specifically, the position of the optical head in step S704 is set as the initial position, and the main body head is driven in the Z direction from the initial position by a preset drive amount, and then switching is made to high-precision alignment.

As another example, the drive amount of the lens 107 may be used for the judgment, similar to the optical head drive amount. In addition, because wide anterior eye observation is also used for fundus observation, there are restrictions on the device when widening the diopter range. Since widening the diopter range would result in an increase in the size of the device, it is desirable to perform diopter correction within the desired range. Therefore, when the lens 107 reaches the end of the diopter correction, the alignment detection means may be switched, and in this case, it is desirable to design the diopter range of the lens 107 to fall within the fine anterior eye observation range.

As another example, detection using fine anterior observation may be performed simultaneously, and when detection becomes possible using fine anterior observation, the alignment detection means may be switched. The alignment detection means may be switched from wide anterior observation to fine anterior observation using any of the above methods or a combination of the above methods.

If it is determined in step S709 that the alignment state is appropriate, the process proceeds to step S710. In step S710, the control unit 20 performs OCT imaging. Specifically, the drive control unit 22 controls the driving of the light source 118, the X scanner 114-1, the Y scanner 114-2, and the lens 115, and the image generation unit 23 generates an OCT tomographic image based on the interference signal output from the line sensor 184. This allows the control unit 20 to obtain an OCT tomographic image at an appropriate position. Note that in step S710, the control unit 20 may perform more detailed alignment using a fundus observation image acquired using the CCD 105 for fundus observation, and then perform OCT imaging. When the OCT imaging process in step S708 ends, the examination is completed in step S711.

Although the examination flow for only one eye has been described here, the examination flow may also be such that OCT imaging is performed on both eyes consecutively. In that case, the above flow can be executed for each of the right and left eyes.

In this embodiment, the input of subject information in step S701 also serves to indicate the start of the examination. However, the method for starting the examination is not limited to this. For example, the start of the examination may be determined by an operation such as turning on the power of the OCT device 1. Alternatively, the start of the examination may be determined by providing a dedicated input, different from the subject information, by the input unit 50 indicating the start of the examination. Furthermore, the end of the previous examination may be determined to be the start of the next examination.

In addition, in this embodiment, the optical head unit 100 is not moved during the OCT imaging in step S710, but this is not limited to the above. Even if the alignment state is once determined to be appropriate, it is possible that the subject's eye E moves during OCT imaging, making it impossible to obtain a suitable OCT tomographic image. For this reason, the alignment control in step S708 may be continued even during OCT imaging.

In addition, when alignment processing is performed using a moving image of an anterior eye observation image displayed on the preview screen, these processes may be performed for each frame of the moving image, or may be performed for each predetermined number of frames of the moving image.

In addition, in the OCT imaging in step S710, images such as an En-Face image or an OCTA front image may be captured together with or instead of the tomographic image and the frontal fundus image. Here, the En-Face image refers to a front image that is generated by projecting or accumulating data corresponding to at least a partial depth range of volume data (three-dimensional tomographic image) obtained using optical interference and that corresponds to a depth range determined based on two reference planes onto a two-dimensional plane.

The OCTA front image refers to a motion contrast front image generated by projecting or accumulating the motion contrast data between multiple volume data corresponding to the depth range described above onto a two-dimensional plane. Here, the motion contrast data is data showing the changes between multiple volume data obtained by controlling the measurement light to scan multiple times in the same region (same position) of the subject's eye.

Here, on the preview screen described above, instead of the fundus front image, an En-Face image or an OCTA front image corresponding to a predetermined depth range may be displayed as a moving image. Also, on the preview screen, instead of the tomographic image, an OCTA tomographic image may be displayed as a moving image.

As described above, the OCT device 1 according to this embodiment includes the optical head unit 100, the face receiving unit 160, the driving members of the stage unit 150 and the face receiving unit 160, the infrared CCD 112, and the CCD 105. The optical head unit 100 functions as an example of a head unit that captures an image of the subject's eye. The face receiving unit 160 functions as an example of a support unit that supports the subject's face. The driving members of the stage unit 150 and the face receiving unit 160 function as an example of a moving unit that can move at least one of the optical head unit 100 and the face receiving unit 160. The infrared CCD 112 functions as an example of an observation unit that captures an image from the optical head unit 100 side toward the face receiving unit 160 side. In this embodiment, the infrared CCD 112 and the CCD 105 capture an anterior eye observation image in front of the optical head unit 100, in other words, in the direction in which the subject is placed.

With this configuration, the alignment operation can be performed with high precision regardless of individual differences in the subject's eye. Therefore, by using the OCT device 1 according to this embodiment, the burden of manual operation by the examiner can be reduced.

In this embodiment, the infrared CCD 112 is used as an example of an anterior ocular observation unit that captures an image of the anterior segment of the subject's eye. This eliminates the need to provide a separate camera or the like for alignment, which reduces costs and makes the device more compact.

This embodiment can also be applied to ophthalmic devices other than OCT devices. For example, the alignment process according to this embodiment can be applied to various ophthalmic devices such as fundus cameras, SLO devices, eye refractive power measuring devices, and tonometers. In such cases, step S708 in FIG. 7 will involve photographing and measurement appropriate to the ophthalmic device.

The alignment process according to this embodiment can also be applied to devices that capture frontal images of the anterior eye and capture OCT images of the anterior segment.

Example 2
In this embodiment, the OCT device described in the first embodiment is improved to include a fundus camera function. The main body head unit 100 in the first embodiment is changed to a main body head unit 500 in this embodiment, and the description of the parts common to the first embodiment will be omitted.

<Configuration>
The OCT device according to the present embodiment is provided with a fundus image capturing section for capturing a two-dimensional fundus image and a tomographic image capturing section for capturing a three-dimensional tomographic image of the fundus of the subject's eye using information based on optical interference. First, the schematic configuration of the OCT device according to the present embodiment will be described with reference to Fig. 8. Fig. 8 shows the schematic configuration of the OCT device according to the present embodiment and its optical system. In the following description, the direction that approximately coincides with the line of sight of the subject's eye E is defined as the Z direction. Also, the plane perpendicular to the Z direction is defined as the XY plane, the horizontal direction is defined as the X direction, and the vertical direction is defined as the Y direction.

The OCT device is equipped with an optical head unit 500 and a spectroscope 600. The configurations of the optical head unit 500 and the spectroscope 600 will be described below in order.

<Configuration of Optical Head Unit 500 and Spectrometer 600>
The optical head unit 500 is provided with an optical system for capturing two-dimensional images and tomographic images of the anterior segment Ea and fundus Ef of the subject's eye E. Various optical systems disposed within the optical head unit 500 will be described below.

In the optical head unit 500, an objective lens 501 is arranged facing the subject's eye E. A first dichroic mirror 502 and a second dichroic mirror 503 that function as an optical path branching unit are arranged on the optical axis L1 of the objective lens 501. The first dichroic mirror 502 and the second dichroic mirror 503 branch 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 measurement optical system (optical axis L5) for each wavelength band.

A lens 520, a prism 521, an aperture 522, a lens 523, and an image sensor 524 are arranged on the optical axis L2 in the reflection direction of the second dichroic mirror 503. The image sensor 524 is a monochrome sensor with sensitivity in the infrared range. The optical members and other components arranged on the optical axis L2 constitute an anterior segment observation system for observing the anterior segment Ea.

The image sensor 524 is connected to a control unit (not shown). The image sensor 524 sends a signal corresponding to the detected light to the control unit (not shown). A light source 525 for observing the anterior eye, arranged near the objective lens 501, illuminates the anterior eye portion Ea of the subject's eye E.

On the optical axis L3 in the transmission direction of the first dichroic mirror 502, a perforated mirror 531, a photographing aperture 532, a focus lens 533, an imaging lens 534, a third dichroic mirror 535, and an image sensor 536 are arranged. The perforated mirror 531 has an opening in the center. The focus lens 533 is held so that it can move in the optical axis direction indicated by the arrow in the figure by a driving unit such as a motor (not shown) controlled by a control unit (not shown). The focus of the fundus photography system can be adjusted by moving the focus lens 533 on the optical axis L3. The optical path on the optical axis L3 is branched by the third dichroic mirror 535 into an optical path leading to the image sensor 536 and an optical path leading to the fixation lamp 537, either for each wavelength band or by transmitting and reflecting a part of the optical path.

The image sensor 536 is a fundus image sensor that is sensitive to visible light and infrared light and is capable of both video observation and still image capture. The image sensor 536 sends a signal corresponding to the detected light to a control unit (not shown). The control unit can generate a fundus observation image or a fundus image (frontal fundus image) based on the signal received from the image sensor 536 and display it on a display unit (not shown). The fixation lamp 537 emits visible light to encourage the subject to fixate. The fixation lamp 537 may also be provided with an aperture (not shown) for cutting the light beam required for fundus photography.

A diopter correction lens 538 can be inserted onto the optical axis L3 using a drive unit such as a motor (not shown). Similarly, the diopter correction lens 538 can be removed from the optical axis L3 using the drive unit. A control unit (not shown) controls the drive unit to control the insertion and removal of the diopter correction lens 538, thereby making it possible to adjust the focus of the fundus photography system over an even wider diopter range.

A corneal baffle 540, a relay lens 541, a focus target unit 542, a lens 543, and a ring slit 544 are arranged in this order on the optical axis L4 in the reflection direction of the perforated mirror 531. The corneal baffle 540 has a light-shielding point in the center. The ring slit 544 has a ring-shaped slit opening. Also arranged on the optical axis L4 are a crystalline lens baffle 545 as a light-shielding member having a light-shielding point, and a dichroic mirror 546 that has the property of transmitting infrared light and reflecting visible light.

The focus target unit 542 is an optical element that provides a target for focusing using the focus lens 533, and in this embodiment, a split bright line is projected as an example of a target. The focus target unit 542 in this embodiment has a split target member that can move along the optical axis L4 in conjunction with the focus lens 533. In addition, the split target member is configured to be inserted into and removed from the optical path of the optical axis L4 by a drive unit such as a motor (not shown) that is controlled by a control unit (not shown).

The split bright lines irradiated by the focus target unit 542 pass through the relay lens 541 and are reflected by the perforated mirror 531 toward the second dichroic mirror 503. The split bright lines reflected by the perforated mirror 531 are projected onto the fundus Ef of the subject's eye E via the second dichroic mirror 503, the first dichroic mirror 502, and the objective lens 501. The control unit (not shown) can calculate the amount of focus shift by detecting the position of the split bright lines from the fundus observation image.

A condenser lens 547 and a white LED light source 548 are arranged in the reflection direction of the dichroic mirror 546. The white LED light source 548 is a light source for photography in which multiple white LEDs that emit visible pulsed light are arranged. In the transmission direction of the dichroic mirror 546, a condenser lens 549 and an infrared LED light source 550 are arranged. The infrared LED light source 550 is an observation light source in which multiple infrared LEDs that emit constant infrared light are arranged. The white LED light source 548 and the infrared LED light source 550 are controlled by a control unit (not shown).

Incidentally, the switching between the white LED and the infrared LED irradiation may be performed by inserting and removing the white LED light source 548 and the infrared LED light source 550 into and from the optical path using a switching mechanism (not shown), which has the advantage of making the dichroic mirror 546 unnecessary. The objective lens 501, the dichroic mirror 546, the optical members therebetween, and the condenser lenses 547 and 549 constitute an illumination optical system for illuminating the fundus Ef. The fundus Ef of the subject's eye E can be illuminated by the light from the white LED light source 548 or the infrared LED light source 550 via the illumination optical system. In addition, a fundus photography system is constituted by the optical members on the optical axes L3 and L4.

On the optical axis L5 in the reflection direction of the first dichroic mirror 502, the lens 551, the mirror 552, the XY scanner 553, the focus lens 554, the collimator lens 555-1, and the fiber end 555-2 are arranged as a measurement optical system. The XY scanner 553 includes an X scanner 553-1 and a Y scanner 553-2. The X scanner 553-1 and the Y scanner 553-2 are composed of any deflection means such as a galvanometer mirror, and function as a scanning unit that scans the measurement light on the fundus Ef of the test eye E. The vicinity of the central positions of the X scanner 553-1 and the Y scanner 553-2 are optically conjugate with the position of the pupil of the test eye E. In FIG. 8, the optical path between the X scanner 553-1 and the Y scanner 553-2 is configured within the plane of the paper, but in reality it is configured in a direction perpendicular to the plane of the paper. In addition, the scanning unit that scans the measurement light may be configured using a MEMS mirror or the like that can deflect light in two dimensions with a single mirror.

In this embodiment, the X scanner 553-1 can scan the measurement light in the X direction, and the Y scanner 553-2 can scan the measurement light in the Y direction perpendicular to the X direction. In this embodiment, an example is described in which the X direction is the main scanning direction and the Y direction is the sub-scanning direction, but the scanning directions are not limited to this. The main scanning direction and the sub-scanning direction in such a scan may be any directions that intersect with each other, for example, the Y direction may be the main scanning direction and the X direction may be the sub-scanning direction. In addition, the main scanning direction and the sub-scanning direction may be diagonal directions having components in the X direction and the Y direction that intersect with each other. In addition, the scanning pattern may be, for example, a 3D scan, a radial scan, a cross scan, a Lissajous scan, a circle scan, or a raster scan.

The measurement light source 557 is a light source that emits light to obtain measurement light to be incident on the measurement optical path. In this embodiment, the measurement light in the OCT optical system is emitted from the fiber end 555-2 of the optical fiber 556-2 as a light source, and the fiber end 555-2 has an optical conjugate relationship with the fundus Ef of the test eye E. The fiber end 555-2 is disposed at the focal position of the collimator lens 555-1, and the measurement light is emitted as a parallel light beam from the fiber end 555-2 acting as a light source through the collimator lens 555-1. The collimator lens 555-1 and the fiber end 555-2 form a coherence gate 555.

The focus lens 554 is a lens for adjusting the focus of the OCT optical system, and is driven in the optical axis direction indicated by the arrow in the figure by a driving unit such as a motor (not shown) controlled by the control unit 300. The focus adjustment is performed so that the measurement light is imaged on the fundus Ef. The focus lens 554 is disposed between the fiber end 555-2, which serves as the measurement light source, and the X scanner 553-1 and Y scanner 553-2, which function as the scanning unit. By the focus adjustment described above, the image of the measurement light emitted from the fiber end 555-2 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 556-2.

Next, the configuration of the optical path from the measurement light source 557, the reference optical system, and the spectrometer 200 will be described. Note that the OCT optical system is made up of the above-mentioned measurement optical system, the optical members included in the optical path from the measurement light source 557, the reference optical system, and the spectrometer 200. In addition, a Michelson interference system is made up of the measurement light source 557, the optical coupler 556, the optical fibers 556-1 to 556-4, the lens 558, the dispersion compensation glass 559, the reference mirror 560, and the spectrometer 200.

In this embodiment, a typical low-coherence light source, SLD (Super Luminescent Diode), is used as the measurement light source 557. The central wavelength of the light emitted from the measurement light source 557 is 880 nm, and the wavelength width is about 60 nm. Here, the wavelength width is an important parameter because it affects the resolution in the optical axis direction of the obtained tomographic image. In addition, an SLD is selected as the type of light source here, but any light source that can emit low-coherence light may be used, for example, ASE (Amplified Spontaneous Emission) or the like. For example, the wavelength of near-infrared light may be used as the central wavelength of the measurement light, in consideration of measuring the eye. In addition, the characteristics of the first dichroic mirror 502 and the second dichroic mirror 503 cause the optical path of the fundus photography system (optical axis L3), the optical path of the measurement optical system (optical axis L5), and the anterior eye observation optical path (optical axis L2) to branch off. Therefore, it is necessary to provide a certain degree of wavelength difference for the wavelengths used in each optical path. In this embodiment, the above wavelengths were selected as the SLD wavelengths from this perspective.

Optical fibers 556-1 to 556-4 are single-mode optical fibers that are connected to and integrated with optical coupler 556. Light emitted from measurement light source 557 is guided to optical coupler 556 via optical fiber 556-1. The light guided to optical coupler 556 is split by optical coupler 556 into measurement light directed toward optical fiber 556-2 and reference light directed toward optical fiber 556-3. Here, optical coupler 556 functions as an example of a splitter that splits the light from measurement light source 557 into measurement light and reference light.

As described above, in this embodiment, the measurement light in the OCT optical system is emitted from the fiber end of the optical fiber 556-2 as a light source. The measurement light passes through the optical path of the measurement optical system described above, is irradiated onto the fundus Ef of the subject's eye E, which is the object of observation, and is reflected and scattered by the retina, and reaches the optical coupler 556 again through the same optical path as return light.

Meanwhile, the reference light passes through optical fiber 556-3, lens 558, and dispersion compensation glass 559 inserted to match the dispersion of the measurement light and reference light, and reaches and is reflected by reference mirror 560. The reference light reflected by reference mirror 560 returns along the same optical path and reaches optical coupler 556 again.

The reference light and the measurement light (return light) that reach the optical coupler 556 again are multiplexed by the optical coupler 556. Here, when the optical path length of the measurement light and the optical path length of the reference light become almost the same, this multiplexing causes interference between the respective lights. The coherence gate 555, which is composed of the collimator lens 555-1 and the fiber end 555-2 of the OCT optical system, is held so that its positional relationship can be adjusted as a whole in the optical axis direction indicated by the arrow in the figure by a driving unit such as a motor (not shown). By using the coherence gate 555, it is possible to match the optical path length of the measurement light, which changes depending on the subject's eye E, to the optical path length of the reference light. The obtained interference light is guided to the spectroscope 600 via the optical fiber 556-4.

Spectrometer 600 is provided with lens 601, diffraction grating 602, lens 603, and line sensor 604. Interference light emitted from optical fiber 556-4 becomes approximately parallel light via lens 601, is then dispersed by diffraction grating 602, and is imaged on line sensor 604 by lens 603. Each element in line sensor 604 generates an interference signal corresponding to the received light, and line sensor 604 sends the interference signal to a control unit (not shown). The control unit samples the interference signal received from line sensor 604 at a predetermined timing, and performs predetermined signal processing to generate a tomographic image.

Furthermore, the optical head unit 500 is provided with a head drive unit (not shown). By controlling the drive of the head drive unit, the optical head unit 500 can be moved in three dimensions (X, Y, Z) relative to the subject's eye E. This allows the control unit (not shown) to align the optical head unit 500 with the subject's eye E.

In this embodiment, a wide anterior observation image is acquired by the image sensor 536, and a fine anterior observation image is acquired by the image sensor 524. The lens having the focus mechanism for the wide anterior observation image is the focus lens 533, and the focus driving method associated with the optical head unit 500 is the same as in embodiment 1, so a description thereof will be omitted.

The acquisition of a fine anterior eye observation image will now be described. This embodiment differs from embodiment 1 in that it includes a prism 521. The effect of the prism 521 will now be described with reference to Figures 9(a) and 9(b).

As shown in FIG. 9A, the lens with prism 110 is provided with Fresnel prisms 521-1 and 521-2. The prism 521 is disposed at a position where the Fresnel prisms 521-1 and 521-2 are conjugate with the anterior segment Ea of the subject's eye E. In this embodiment, the prism 521 is disposed so that the image formed by the light beam passing through the lens with prism 521 is divided into upper and lower parts according to the distance between the optical head unit 500 and the subject's eye E due to the prism effect of the Fresnel prisms 521-1 and 521-2. However, the direction in which the image is divided by the prism effect may be set arbitrarily according to the desired configuration, and the prism 521 may be disposed in an arbitrary direction accordingly.

Here, we will describe the positional relationship between the optical head unit 100 and the subject's eye E, that is, the case where the alignment position is in the ideal position. In this case, the light beam of reflected and scattered light from the anterior segment Ea of the subject's eye E is imaged once on the Fresnel prisms 521-1 and 521-2 of the prism 521, and the image is split (image split) due to the prism effect of the Fresnel prisms 521-1 and 521-2. However, since the shooting surface of the image sensor 524 is also conjugate with the Fresnel prisms 521-1 and 521-2, the anterior eye observation image captured using the image sensor 524 becomes like the anterior eye observation image 901 in FIG. 9(b). In the anterior eye observation image 901, the anterior eye image is at the center of the image, and the upper and lower halves of the pupil image match.

In contrast, if the alignment position is not ideal in the x and y directions, the anterior eye observation image will look like anterior eye observation image 902 in FIG. 9(b). In anterior eye observation image 902, the anterior eye image is offset from the center of the image, but the position in the z direction is ideal, so the upper and lower halves of the pupil image match.

Next, when the alignment position is at the ideal position in the xy direction and farther than the ideal position in the z direction (the distance between the optical head unit 500 and the subject's eye E is longer than the ideal distance), the anterior eye observation image will look like anterior eye observation image 903 in FIG. 9(b). In anterior eye observation image 903, the anterior eye image is at the center of the image, but the upper and lower halves of the pupil image are misaligned.

Similarly, if the alignment position is not in the ideal position in the xyz directions (or the xz directions or the yz directions), the anterior eye image in the anterior eye observation image captured using the image sensor 524 will be shifted from the center of the image, and the upper and lower halves of the pupil image will also be shifted. For example, if the alignment position is not in the ideal position in the x direction and is closer than the ideal position in the z direction (the distance between the optical head unit 500 and the subject's eye E is shorter than the ideal distance), the anterior eye observation image will be like the anterior eye observation image 904 in FIG. 9(b). In the anterior eye observation image 904, the anterior eye image is shifted laterally from the center of the image in the anterior eye observation image 902, and the upper and lower halves of the pupil image are shifted. In addition, in the anterior eye observation image 904, the direction of deviation between the upper and lower halves of the pupil image is opposite to the direction of deviation between the upper and lower halves of the pupil image in the anterior eye observation image 903, and it can be seen that the deviation directions in the z direction of the alignment positions corresponding to each image are opposite.

In the configuration of Example 1, when setting the range of the switching range of Example 1 where detection is possible with fine anterior observation, the detectable range with fine anterior observation can also be set to the range where the split image is detectable at the center.

By providing the above mechanism, alignment can be performed using the fine anterior observation image of this embodiment. On the other hand, alignment using the wide anterior observation image will be explained below.

The wide anterior eye observation image is illuminated using an infrared LED light source 550. When the optical head unit 500 is located near the working distance for observing and photographing the fundus Ef of the subject's eye E, the fundus Ef of the infrared LED light source 550 is illuminated. On the other hand, when the optical head unit 500 is outside the working distance for observing and photographing the fundus Ef, the anterior eye Ea of the subject's eye E is illuminated, and the wide anterior eye observation image is acquired by the image sensor 536.

The diopter correction lens 538 may be used to focus the wide anterior eye observation image. In particular, it is possible to use a diopter correction lens on the + diopter side to obtain a wide anterior eye image and drive the focus lens 533 according to the position of the optical head unit 500. Considering that the image becomes discontinuous when the diopter correction lens is inserted or removed, it is desirable to perform alignment using the wide anterior eye observation image while the diopter correction lens on the + diopter side is inserted. However, in order to avoid discontinuity, the position of the focus lens 533 that becomes the same diopter when the diopter correction lens is inserted or removed may be stored, and the focus lens 533 may be moved to the stored position instantly when the diopter correction lens is inserted or removed.

Other than the above, the configuration and shooting process are the same as in Example 1, so the explanation will be omitted.

(Modification)
In the first and second embodiments, the wide anterior observation image and the fine anterior observation image are acquired independently, but they may be shared. For example, in the second embodiment, an anterior observation optical path L2 leading to the image sensor 524 is provided. However, by disposing an insertable/removable optical system (not shown) between the objective lens 501 and the perforated mirror 531, for example, the image sensor 536 may be shared to acquire the wide anterior observation image and the fine anterior observation image.

The configuration of the measurement optical system in the ophthalmic device according to the above-mentioned embodiment is one example, and may be changed as desired.

This disclosure includes the following configurations and methods:

(Configuration 1)
a first optical system for imaging a fundus of the subject's eye, the first optical system including an objective lens facing the subject's eye and a focusing device;
a second optical system for imaging the anterior segment of the eye, the second optical system including the objective lens;
an alignment means for changing a relative position between the eye and the objective lens;
a control unit that performs a first control for controlling the alignment unit based on an image captured by the first optical system, and a second control for controlling the alignment unit based on an image captured by the second optical system,
an initial position of the first control is set to a position farther from the subject's eye than a predetermined position within a driving range of the alignment means;
The control means adjusts the focus means while changing the relative position,
The second control is started after the first control is started.

(Configuration 2)
the driving ranges of the first control and the second control overlap with each other;
2. The ophthalmologic apparatus according to configuration 1, wherein the control unit switches from the first control to the second control when the alignment unit reaches the predetermined position.

(Configuration 3)
3. The ophthalmologic apparatus according to claim 1, wherein the predetermined position is determined based on a result of detecting that the movement of the alignment means has reached a predetermined amount.

(Configuration 4)
3. The ophthalmic apparatus according to claim 1, wherein the predetermined position is determined based on a position of the focusing means, or is within an area detectable by the second optical system.

(Configuration 5)
the second optical system includes a configuration in which an image is split depending on a distance between the subject's eye and a main body head unit,
5. The ophthalmologic apparatus according to configuration 4, wherein the detectable area is an area in which the position of the subject's eye can be detected in the split image.

(Configuration 6)
6. The ophthalmologic apparatus according to any one of configurations 1 to 5, wherein the adjustment of the focusing means is performed by driving the focusing means using a driving method that is stored in advance in accordance with a driving amount of the alignment means.

(Configuration 7)
6. The ophthalmic apparatus according to any one of configurations 1 to 5, wherein the adjustment of the focusing means is driven based on the state of the image of the first optical system.

(Method 1)
A control method for an ophthalmologic apparatus having a first optical system for imaging a fundus of a subject's eye, the first optical system including an objective lens facing the subject's eye and a focusing device, a second optical system for imaging an anterior segment of the eye, the second optical system including the objective lens, and an alignment device for changing a relative position between the subject's eye and the objective lens, the method comprising:
performing a first control for controlling the alignment means based on an image captured by the first optical system;
performing a second control of controlling the alignment means based on an image captured by the second optical system;
The first control sets a position farther from the subject's eye than a predetermined position within a driving range of the alignment means as an initial position,
adjusting the focusing means while changing the relative position;
A control method for an ophthalmic apparatus, wherein the second control is started after the first control is started.

(program)
A program for causing a computer to execute the method for controlling an ophthalmic apparatus according to the method 1.

Other Examples
The disclosed technology can also be realized by executing the following process. That is, the disclosed technology 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, etc.) 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.

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 gate array (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 (9)

a first optical system for imaging a fundus of the subject's eye, the first optical system including an objective lens facing the subject's eye and a focusing device;
a second optical system for imaging the anterior segment of the eye, the second optical system including the objective lens;
an alignment means for changing a relative position between the eye and the objective lens;
a control unit that performs a first control for controlling the alignment unit based on an image captured by the first optical system, and a second control for controlling the alignment unit based on an image captured by the second optical system,
an initial position of the first control is set to a position farther from the subject's eye than a predetermined position within a driving range of the alignment means;
The control means adjusts the focus means while changing the relative position,
The second control is started after the first control is started. the driving ranges of the first control and the second control overlap with each other;
The ophthalmic apparatus according to claim 1 , wherein the control means switches from the first control to the second control when the alignment means reaches the predetermined position. The ophthalmic device according to claim 1, wherein the predetermined position is determined based on the result of detecting that the movement of the alignment means has reached a predetermined amount. The ophthalmic device according to claim 1, wherein the predetermined position is determined based on the position of the focusing means, or is within an area detectable by the second optical system. the second optical system includes a configuration in which an image is split depending on a distance between the subject's eye and a main body head unit,
The ophthalmologic apparatus according to claim 4 , wherein the detectable area is an area in which the position of the subject's eye can be detected in the split image. The ophthalmic device according to claim 1, wherein the focus means is adjusted by a drive method stored in advance according to the drive amount of the alignment means. The ophthalmic device according to claim 1, wherein the adjustment of the focus means is driven based on the state of the image of the first optical system. A control method for an ophthalmologic apparatus having a first optical system for imaging a fundus of a subject's eye, the first optical system including an objective lens facing the subject's eye and a focusing device, a second optical system for imaging an anterior segment of the eye, the second optical system including the objective lens, and an alignment device for changing a relative position between the subject's eye and the objective lens, the method comprising:
performing a first control for controlling the alignment means based on an image captured by the first optical system;
performing a second control of controlling the alignment means based on an image captured by the second optical system;
an initial position of the first control is set to a position farther from the subject's eye than a predetermined position within a driving range of the alignment means;
adjusting the focusing means while changing the relative position;
A control method for an ophthalmic apparatus, wherein the second control is started after the first control is started. A program for causing a computer to execute the method for controlling an ophthalmic apparatus according to claim 8.

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