microscope

Abstract

To provide a microscope capable of fixing a visual axial direction of an eye to be examined while scanning the eye to be examined with illumination light.SOLUTION: A microscope equipped with a relative movement mechanism for relatively moving a Scheimpflug optical system including an illumination system and an imaging system with respective to an eye to be examined and scanning the eye to be examined with illumination light, in which an object surface including an illumination light axis, a principal surface of an optical system, and an imaging surface satisfy a Scheimpflug condition includes a fixation optical system in which a relative position with the eye to be examined is fixed, having a projection light axis defferent from the illumination light axis and an imaging light axis of the imaging system, and projecting fixation light onto the eye to be examined along the projection light axis. The fixation optical system projects the fixation light onto the eye to be examined at least while the relative movement of the Scheimpflug optical system is executed by the relative movement mechanism.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a microscope equipped with a Scheimpflug optical system. [Background technology]

[0002] The slit lamp microscope described in Patent Document 1 includes a Scheimpflug optical system that functions as a Scheimpflug camera. The Scheimpflug optical system includes an illumination system and an imaging system including a lens system and an image sensor. These illumination and imaging systems are configured to satisfy the Scheimpflug condition, in which a plane including an object plane (a plane focused on the image sensor described below) including the illumination optical axis of the illumination system, a plane including the principal plane of the lens system, and a plane including the image sensor's image sensor intersect on the same straight line. This allows imaging to be performed while focusing on all positions within the object plane. For example, the slit lamp microscope described in Patent Document 1 performs imaging while focusing on a cross section of the anterior segment of the subject's eye (from the anterior surface of the cornea to the posterior surface of the crystalline lens).

[0003] In addition, the slit lamp microscope described in Patent Document 1 continuously photographs cross sections of the anterior eye segment using an imaging system while moving a Scheimpflug optical system in a direction perpendicular to the object plane (illumination optical axis), thereby scanning the entire cornea of the anterior eye segment with slit light and acquiring a cross-sectional image of the anterior eye segment for each scanning position.The slit lamp microscope then generates a three-dimensional image of the anterior eye segment based on the cross-sectional image of the anterior eye segment for each scanning position. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-213733 Summary of the Invention [Problem to be solved by the invention]

[0005] Visible light is generally used as the slit light irradiated onto the anterior segment of the subject's eye from the illumination system of a slit lamp microscope. Therefore, there is a risk that the subject's gaze direction will change if they follow the slit light while it is scanning the anterior segment. Since this makes it impossible to obtain a good 3D image of the anterior segment, it is necessary for the subject to fixate the gaze direction of the subject's eye while the slit light is scanning.

[0006] Here, for example, an optical coherence tomography (OCT) device and a scanning laser ophthalmoscope (SLO) are provided with a light projecting and receiving optical system that scans the subject's eye with various measurement lights and receives return light from the subject's eye, and a fixation optical system that fixates the subject's eye. The OCT device and the SLO are designed to fixate the subject's eye so that the subject does not follow the measurement light with their eyes.

[0007] However, in the OCT device and SLO, the projection and reception optical system and the fixation optical system share a common objective lens (optical system). Therefore, if the fixation optical system of the OCT device and SLO were applied to the slit lamp microscope described in Patent Document 1, the fixation optical system would move together with the Scheimpflug optical system when scanning the anterior segment of the eye with slit light, making it impossible to fixate the eye to be examined.

[0008] The present invention has been made in consideration of the above circumstances, and aims to provide a microscope that can fix the line of sight of the subject's eye while the Scheimpflug optical system is moved relative to the subject's eye, i.e., while the subject's eye is scanned with illumination light. [Means for solving the problem]

[0009] A microscope for achieving the object of the present invention comprises an illumination system having an illumination optical axis and irradiating an eye under examination with illumination light along the illumination optical axis, a first imaging element, and an optical system that directs return light from the eye under examination irradiated with the illumination light to the imaging surface of the first imaging element, and an imaging system that images the return light using the first imaging element, and a relative movement mechanism that moves a Scheimpflug optical system including the illumination system and the imaging system relative to the eye under examination to scan the eye under examination with the illumination light, in which the object plane including the illumination optical axis, the principal plane of the optical system, and the imaging surface satisfy the Scheimpflug condition, and the microscope comprises a fixation optical system whose relative position with the eye under examination is fixed and which has a projection optical axis different from the illumination optical axis and the imaging optical axis of the imaging system, and which projects fixation light onto the eye under examination along the projection optical axis, and the fixation optical system projects fixation light onto the eye under examination at least while the Scheimpflug optical system is being moved relative to the eye under examination by the relative movement mechanism.

[0010] According to this microscope, while the eye to be examined is scanned with illumination light, fixation light can be projected onto the eye to be examined from a fixation optical system whose relative position with respect to the eye to be examined is fixed.

[0011] In a microscope according to another aspect of the present invention, the fixation optical system projects fixation light onto the subject's eye, which allows the subject to recognize the direction and amount of positional deviation of the subject's eye from a predetermined assumed position of the subject's eye, thereby allowing the subject to appropriately adjust the position of the subject's eye (face).

[0012] In a microscope according to another aspect of the present invention, the shape and beam diameter of the fixation light projected by the fixation optical system onto the subject's eye are set so that when the positional deviation is within a predetermined range, the entire fixation light is projected onto the subject's eye, and when the positional deviation exceeds the predetermined range, the shape and beam diameter are set so that the fixation light is vignetted according to the direction and amount of the positional deviation. This allows the subject to recognize the direction and amount of the positional deviation, and therefore allows the position of the subject's eye (face) to be appropriately adjusted.

[0013] In a microscope according to another aspect of the present invention, the shape of the fixation light is a cross, which allows the subject to recognize the direction and amount of positional deviation.

[0014] In a microscope according to another aspect of the present invention, the fixation optical system projects fixation light onto the subject's eye through a pinhole, thereby increasing the depth of field of the fixation optical system.

[0015] In another aspect of the microscope of the present invention, an observation system is provided which is fixed in position relative to the subject's eye, has a common observation optical axis with a part of the projection optical axis, and guides return light from the subject's eye that is incident along the observation optical axis to a second imaging element or an eyepiece.

[0016] In a microscope according to another aspect of the present invention, when the direction parallel to the illumination optical axis among the mutually orthogonal X, Y, and Z directions is defined as the Z direction, the imaging optical axis is perpendicular to the Y direction and is inclined with respect to the illumination optical axis when viewed from the Y direction, and the projection optical axis overlaps with the illumination optical axis when viewed from the Y direction and is inclined with respect to the illumination optical axis when viewed from the X direction.

[0017] In a microscope according to another aspect of the present invention, an illumination system irradiates the anterior segment of the eye to be examined with slit-shaped illumination light parallel to the object plane, and a relative movement mechanism moves the Scheimpflug optical system in a direction perpendicular to the object plane. [Effects of the Invention]

[0018] The present invention can fix the line of sight of the subject's eye while the subject's eye is scanned with illumination light. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 2 is a side view of the slit lamp microscope as seen from the X direction side. [Figure 2] FIG. 2 is a top view of the slit lamp microscope as seen from the Y direction side. [Figure 3] FIG. 2 is an explanatory diagram for explaining the configurations and arrangement conditions of an illumination system and an imaging system. [Figure 4] 2 is an enlarged top view of the fixation optical system in FIG. 1 as viewed from above in the Y direction. [Figure 5] FIG. 10 is an explanatory diagram showing an example of a fixation target presented to a subject when the positional deviation of the subject's eye is within a specified range. [Figure 6] 10 is an explanatory diagram showing an example of a fixation target presented to a subject when a positional deviation of the subject's eye exceeds a specified range. FIG. [Figure 7] 7 is an explanatory diagram showing an example of a fixation target presented to the subject when the positional deviation of the subject's eye is larger than that in the example shown in FIG. 6. FIG. [Figure 8] 10 is a flowchart showing the flow of a process for generating a three-dimensional image of the anterior segment of the eye using a slit lamp microscope. [Figure 9] FIG. 10 is an explanatory diagram for explaining a modified example of the observation system of the slit lamp microscope. DETAILED DESCRIPTION OF THE INVENTION

[0020] [Overall configuration of a slit lamp microscope] Fig. 1 is a side view of the slit lamp microscope 10 as viewed from the X direction. Fig. 2 is a top view of the slit lamp microscope 10 as viewed from the Y direction. Of the mutually orthogonal X, Y, and Z directions in the figure, the Z direction is a front-to-back direction (also called the working distance direction) parallel to the front direction approaching the subject's eye E and the rear direction away from the subject, the X direction is a left-to-right direction based on the subject, and the Y direction is a direction perpendicular to both the X and Z directions (here, the up-down direction).

[0021] 1 and 2, a slit lamp microscope 10 corresponds to the microscope of the present invention and generates a three-dimensional image of the anterior segment Ea of the subject's eye E. This slit lamp microscope 10 mainly includes a Scheimpflug optical system 12, a moving mechanism 14, an observation system 50, a fixation optical system 80, and a control device 100.

[0022] [Scheimpflug optical system] The Scheimpflug optical system 12 is held so as to be movable in the X direction by a moving mechanism 14 (described later), and performs cross-sectional imaging along the YZ plane of the anterior segment Ea of the subject's eye E. The Scheimpflug optical system 12 is composed of an illumination system 20 and imaging systems 30R and 30L. Note that the imaging systems 30R and 30L are omitted from FIG. 1 to avoid complication of the drawing.

[0023] <Lighting> The illumination system 20 has an illumination optical axis O1 parallel to the Z direction, and irradiates the anterior segment Ea of the subject's eye E with slit-shaped illumination light L (slit light LS) along this illumination optical axis O1. The illumination system 20 may have a configuration similar to that of an illumination system of a conventional slit lamp microscope, and includes, for example, an illumination light source 22, a slit forming unit 24, and an objective lens 26, which are arranged along the illumination optical axis O1.

[0024] The illumination light source 22 is, for example, an LED (light emitting diode), and emits illumination light L. Visible light is used as the illumination light L, but infrared light (near-infrared light) may also be used. The illumination light L emitted from the illumination light source 22 passes through a lens or the like (not shown) and then enters the slit forming portion 24.

[0025] The illumination light source 22 may be composed of multiple light sources. For example, the illumination light source 22 may include a light source that outputs continuous light and an illumination light source that outputs flash light. The illumination light source 22 may also include an illumination light source for the anterior segment and an illumination light source for the posterior segment. Furthermore, the illumination light source 22 may include multiple light sources that output illumination light L with different wavelengths.

[0026] The slit forming unit 24 has, for example, a pair of slit blades parallel to the Y direction, and by changing the distance between these slit blades in the X direction (slit width), changes the width of the area through which the illumination light L passes. As a result, the illumination light L that has passed through the slit forming unit 24 becomes slit light LS whose width direction is the X direction and whose length direction is the Y direction at the anterior segment position when focused.

[0027] The length of the slit light LS in the Y direction is set to be equal to or greater than the diameter of the cornea on the surface of the anterior eye segment Ea. The slit forming unit 24 may be configured to be able to change the length of the slit light LS in the Y direction.

[0028] The objective lens 26 irradiates the anterior segment Ea with the illumination light L that has passed through the slit forming portion 24. As a result, the anterior segment Ea is irradiated with the slit light LS.

[0029] The illumination system 20 may further include a focusing optical system (not shown) for changing the focus position of the slit light LS.

[0030] <Photography> The imaging systems 30R and 30L capture images of the anterior segment Ea illuminated by the slit light LS from two different directions. The imaging systems 30R and 30L may have the same configuration as the imaging systems of conventional slit lamp microscopes. For example, the imaging system 30R includes an optical system 32R and an image sensor 34R arranged along the imaging optical axis O2R. The imaging system 30L also includes an optical system 32L and an image sensor 34L arranged along the imaging optical axis O2L.

[0031] The photographing optical axis O2R is parallel to the ZX plane and is inclined at an angle θR toward one side of the X direction with respect to the Z direction when viewed from the Y direction. The photographing optical axis O2L is parallel to the ZX plane and is inclined at an angle θL toward the other side of the X direction with respect to the Z direction when viewed from the Y direction. The angles θR and θL may be equal to or different from each other. The illumination optical axis O1, the photographing optical axis O2R, and the photographing optical axis O2L intersect at a single point.

[0032] Although not shown, the optical system 32R includes, for example, an objective lens, a variable magnification optical system, and an imaging lens, in that order from the side closest to the subject's eye E. Return light LA from the anterior eye segment Ea passes through the objective lens and variable magnification optical system of the optical system 32R, and is imaged on the imaging surface 36R of the image sensor 34R by the imaging lens of the optical system 32R. The optical system 32R may further include a focusing optical system (not shown).

[0033] The return light LA from the anterior segment Ea includes the return light of the slit light LS irradiating the anterior segment Ea, and may also include other light. Examples of the return light LA include reflected light, scattered light, and fluorescent light. Examples of other light include light from the installation environment of the slit lamp microscope 10 (room light, sunlight, etc.). If an anterior segment illumination system (not shown) for illuminating the entire anterior segment Ea is provided separately from the illumination system 20, the return light (reflected light) of the anterior segment illumination light from this anterior segment illumination system may be included in the "other light."

[0034] The image sensor 34R, together with the image sensor 34L described below, constitutes a first image sensor of the present invention. The image sensor 34R is a CMOS (complementary metal oxide semiconductor) or CCD (charge coupled device) area sensor having a two-dimensional image sensor surface 36R. The image sensor 34R captures an image of the return light LA formed on the image sensor surface 36R by the optical system 32R, and outputs an anterior segment cross-sectional image DR, which is an image of the return light LA, to the control device 100. The anterior segment cross-sectional image DR is an image of the YZ cross section at the slit light irradiation position of the anterior segment Ea.

[0035] The optical system 32L has the same configuration as the optical system 32R described above, and although not shown, includes an objective lens, a variable magnification optical system, an imaging lens, etc., and may further include a focusing optical system. As a result, the return light LA from the anterior segment Ea irradiated with the slit light LS passes through the objective lens and variable magnification optical system of the optical system 32L and is imaged on the imaging surface 36L of the image sensor 34L by the imaging lens of the optical system 32L.

[0036] The image sensor 34L is a CMOS or CCD area sensor having a two-dimensional image pickup surface 36L, and captures the return light LA formed on the image pickup surface 36L by the optical system 32L, and outputs an anterior-segment cross-sectional image DL, which is an image of the return light LA, to the control device 100. The anterior-segment cross-sectional image DL is an image of the YZ cross section at the slit light irradiation position of the anterior segment Ea.

[0037] <Scheimpflug camera> 3 is an explanatory diagram for explaining the configuration and arrangement conditions of the illumination system 20 and the imaging systems 30R and 30L. As shown in FIG. 3, the illumination system 20 and the imaging system 30L function as a Scheimpflug camera, and the illumination system 20 and the imaging system 30R also function as a Scheimpflug camera.

[0038] As shown by reference numeral 3A in Figure 3, the illumination system 20 and the imaging system 30L are configured so that an object plane SP (a plane on which the imaging planes 36R and 36L are focused) that includes the illumination optical axis O1 and is parallel to the YZ plane, a principal plane SL of the optical system 32L, and the imaging plane 36L satisfy the Scheimpflug condition (principle). More specifically, a plane H1 that includes the object plane SP, a plane H2L that includes the principal plane SL, and a plane H3L that includes the imaging plane 36L intersect on the same straight line. As a result, the imaging system 30L focuses on all positions within the object plane SP (for example, the range from the anterior surface of the cornea to the posterior surface of the lens of the anterior eye segment Ea) and captures the image, i.e., captures a cross-sectional image of the anterior eye segment Ea, thereby obtaining a cross-sectional image DL of the anterior eye segment.

[0039] Similarly, as shown by reference numeral 3B in Fig. 3, the illumination system 20 and the imaging system 30R are configured so that the object plane SP, the principal plane SR of the optical system 32R, and the imaging plane 36R satisfy the Scheimpflug condition. More specifically, the plane H1, the plane H2R including the principal plane SR, and the plane H3R including the imaging plane 36R intersect on the same straight line. As a result, the imaging system 30R also focuses on all positions within the object plane SP (the range from the anterior surface of the cornea to the posterior surface of the lens of the anterior eye segment Ea) and performs cross-sectional imaging of the anterior eye segment Ea, thereby obtaining a cross-sectional image DR of the anterior eye segment.

[0040] The configuration of the illumination system 20 and the imaging systems 30R, 30L that satisfies the Scheimpflug condition is realized by the configuration and arrangement of elements included in the illumination system 20, the configuration and arrangement of elements included in the imaging systems 30R, 30L, and the relative positions of the illumination system 20 and the imaging systems 30R, 30L. Parameters indicating the relative positions of the illumination system 20 and the imaging systems 30R, 30L include, for example, the above-mentioned angles θR, θL. The angles θR, θL are set to, for example, 17.5 degrees, 30 degrees, or 45 degrees. Note that the angles θR, θL may be variable.

[0041] [Moving mechanism] The moving mechanism 14 corresponds to the relative moving mechanism of the present invention, and although not shown, is composed of a stage on which the Scheimpflug optical system 12 is mounted, and an actuator such as a motor that moves this stage in the X, Y, and Z directions. Note that the configuration of the moving mechanism 14 is not particularly limited as long as it can move the Scheimpflug optical system 12 relative to the subject's eye E, and for example, the moving mechanism 14 may be one that moves a face support unit (not shown).

[0042] When aligning the Scheimpflug optical system 12 with the subject's eye E, the moving mechanism 14 performs alignment (auto-alignment) of the Scheimpflug optical system 12 with the subject's eye E by adjusting the position of the Scheimpflug optical system 12 in the XYZ directions under the control of the control device 100 described below.

[0043] Furthermore, when generating a 3D image of the anterior eye segment Ea, the moving mechanism 14, under the control of the control device 100 (described later), moves the Scheimpflug optical system 12 in a direction perpendicular to the illumination optical axis O1 in accordance with the illumination of the anterior eye segment Ea by the illumination system 20 with the slit light LS and the capture of the anterior eye segment cross-sectional images DR and DL by the imaging systems 30R and 30L. More specifically, the moving mechanism 14 moves the Scheimpflug optical system 12 in the X direction, which is a direction perpendicular to the object plane SP. This allows the anterior eye segment Ea to be scanned in the X direction with the slit light LS parallel to a YZ plane, with the X direction being the width direction and the Y direction being the length direction. In this embodiment, the range of movement of the Scheimpflug optical system 12 in the X direction by the moving mechanism 14, i.e., the scanning range of the slit light LS in the X direction relative to the anterior eye segment Ea, is set to a range that includes at least the cornea of the anterior eye segment Ea. This allows the slit light LS to scan the entire cornea.

[0044] In this way, by scanning the anterior eye segment Ea in the X direction with the slit light LS from the illumination system 20 using the movement mechanism 14, the imaging systems 30R, 30L capture the returned light LA (video image capture) and continuously output the anterior eye segment cross-sectional images DR, DL, thereby obtaining the anterior eye segment cross-sectional images DR, DL of the anterior eye segment Ea for each scanning position of the slit light LS in the X direction (see Patent Document 1 mentioned above). Note that the movement mechanism 14 used for alignment and the movement mechanism 14 that moves the Scheimpflug optical system 12 in the X direction may be separate entities.

[0045] [Observation system] Returning to FIG. 1, the observation system 50 is provided independently of the Scheimpflug optical system 12, and its position is fixed within the slit lamp microscope 10, that is, its position relative to the eye E to be examined is fixed.

[0046] The observation system 50 has an observation optical axis O3, and includes an optical system 52 and an image sensor 54 arranged along the observation optical axis O3 in this order from the side closest to the eye E to be examined.

[0047] The observation optical axis O3 (the same applies to a projection optical axis O4 described later) overlaps with the illumination optical axis O1 when viewed from the Y direction, and is tilted downward in the Y direction (or upward in the Y direction) with respect to the illumination optical axis O1 when viewed from the X direction by an inclination angle θ. This inclination angle θ is set to an appropriate angle, for example, approximately 8 degrees, so that the slit light LS irradiated from the illumination system 20 onto the anterior eye segment Ea is not vignetted by the observation system 50 and a fixation optical system 80 described later. This prevents a decrease in the light intensity of the slit light LS irradiated from the illumination system 20 onto the anterior eye segment Ea.

[0048] The optical system 52 includes an imaging lens (not shown) and forms an image of the return light LB (corresponding to the second return light) from the subject's eye E on the imaging element 54. The optical system 52 may include a focusing optical system.

[0049] The return light LB from the subject's eye E includes return light (anterior segment reflected light) of anterior segment illumination light irradiated onto the anterior segment Ea from the above-described anterior segment illumination system (not shown).

[0050] The image sensor 54 is a CMOS or CCD area sensor, and corresponds to the second image sensor of the present invention. The image sensor 54 captures the returned light LB formed by the optical system 52, and outputs an observation image D of the subject's eye E (an anterior segment image obtained by capturing the anterior segment Ea) to the control device 100.

[0051] [Fixation optical system] 4 is an enlarged top view of the fixation optical system 80 in FIG. 1, viewed from above in the Y direction. The Z1 direction in the figure is inclined at an angle θ with respect to the Z direction, i.e., parallel to the observation optical axis O3. The Y1 direction in the figure is perpendicular to both the Z1 and X directions.

[0052] As shown in Fig. 4 and the above-described Fig. 1, the fixation optical system 80 projects (irradiates) fixation light LF onto the fundus Ef of the subject's eye E. The fixation optical system 80 has a projection optical axis O4 that is common to a part of the observation optical axis O3 of the observation system 50, i.e., is coaxial with the observation system 50. The projection optical axis O4 branches off from the observation optical axis O3 halfway, and the section from this branching point to the subject's eye E is common to the observation optical axis O3. Note that instead of branching the projection optical axis O4 halfway from the observation optical axis O3, the observation optical axis O3 may also branch off from the projection optical axis O4 halfway.

[0053] The fixation optical system 80 includes a fixation light source 81, a diffuser 82, a pinhole member 83, a lens 84, a cross reticle plate 85, a lens 86, and a mirror 87, which are arranged along the projection optical axis O4.

[0054] The fixation light source 81 is, for example, a green LED, and emits visible green light as the fixation light LF. The fixation light LF emitted from the fixation light source 81 is diffused by a diffuser plate 82 and then passes through a pinhole 83a formed in a pinhole member 83. By reducing the diameter of the pinhole 83a at this time, the depth of field of the fixation optical system 80 can be increased. As a result, even if the fixation optical system 80 does not have a focusing mechanism, the focus position of the fixation light LF can be adjusted to a certain diopter range.

[0055] The fixation light LF that has passed through the pinhole 83a passes through a cross reticle plate 85 via a lens 84. This causes the fixation light LF in a cross shape to be projected onto the fundus Ef. Then, the fixation light LF that has passed through the cross reticle plate 85 passes through a lens 86 and is incident on a mirror 87.

[0056] The mirror 87 is, for example, a dichroic mirror or a half mirror, and is arranged at a position where the projection optical axis O4 branches off from the observation optical axis O3. The mirror 87 reflects the fixation light LF incident from the lens 86 toward the subject's eye E, and conversely, transmits the return light LB incident from the subject's eye E and emits it toward the optical system 52.

[0057] In this way, the fixation optical system 80 projects the fixation light LF onto the fundus Ef along the projection optical axis O4. At this time, the beam diameter φ of the fixation light LF on the pupil of the subject's eye E is adjusted to, for example, 4.5 mm. As a result, as shown in the fundus image Df of the area within the fundus Ef surrounded by the dotted circle C in the figure, a cross-shaped fixation light LF is formed on the fundus Ef, and a cross-shaped fixation target FP is presented to the subject's eye E. As a result, the gaze direction of the subject's eye E can be fixed in the direction of the fixation target FP, i.e., the subject's eye E can be fixated.

[0058] Furthermore, since the fixation optical system 80 is provided in the observation system 50 whose relative position with respect to the subject's eye E is fixed, the fixation of the subject's eye E can be stabilized (continued) even when the Scheimpflug optical system 12 is moved in the X direction by the moving mechanism 14, i.e., even when the anterior eye segment Ea is scanned in the X direction by the slit light LS.

[0059] In this embodiment, the fixation optical system 80 is used for rough alignment (also called simple alignment), which is a position adjustment of the subject's eye E (face) relative to the slit lamp microscope 10. For example, if the slit lamp microscope 10 is a screenoscope type, the subject needs to look into an eyepiece peephole (not shown) provided in the slit lamp microscope 10. At this time, the subject's eye E may be displaced in a direction perpendicular to the illumination optical axis O1 (XY direction) from the assumed position assumed by the slit lamp microscope 10 (hereinafter simply referred to as "displacement").

[0060] In such a case, if the positional deviation of the subject's eye E is within a predetermined range (also referred to as an allowable range) from the assumed position, for example, within the observation range of the observation system 50, it is possible to detect the relative position of the subject's eye E with respect to the Scheimpflug optical system 12 (alignment detection) and to align the Scheimpflug optical system 12 with the subject's eye E. However, if the positional deviation of the subject's eye E exceeds the above-mentioned specified range, it is impossible to perform alignment detection and alignment.

[0061] Therefore, in this embodiment, the subject can recognize the direction and amount of positional displacement of the subject's eye E from its assumed position based on the fixation target FP presented to the subject's eye E by the fixation optical system 80, and can also recognize whether or not this positional displacement is within the above-mentioned specified range. For this reason, the shape of the fixation light LF and the beam diameter φ on the pupil are set so that when the positional displacement of the subject's eye E from its assumed position is within the specified range, the entire fixation light LF is projected onto the fundus Ef, and conversely, when the positional displacement exceeds the specified range, the fixation light LF projected onto the fundus Ef is vignetted according to the direction and amount of positional displacement.

[0062] Specifically, in this embodiment, the shape of the fixation light LF projected onto the fundus Ef is set to a cross shape as described above, and the beam diameter φ on the pupil (the size of the fixation target FP presented to the subject) is set so that the fixation light LF is vignetted if the positional deviation exceeds a specified range.

[0063] Fig. 5 is an explanatory diagram showing an example of a fixation target FP presented to the subject when the positional deviation of the subject's eye E is within a specified range. Fig. 6 is an explanatory diagram showing an example of a fixation target FP presented to the subject when the positional deviation of the subject's eye E exceeds a specified range. Fig. 7 is an explanatory diagram showing an example of a fixation target FP presented to the subject when the positional deviation of the subject's eye E is greater than the example shown in Fig. 6. Note that Figs. 6 and 7 show an example of vignetting of the fixation target FP, and the state of vignetting of this fixation target FP differs depending on the diopter, pupil diameter, and alignment position in the Z direction of the subject's eye E.

[0064] 5, when the positional deviation of the subject's eye E is within a specified range, the subject can see the entire cross-shaped fixation target FP. In this case, the subject can easily recognize that position adjustment (rough alignment) of the subject's eye E (face) is not necessary.

[0065] On the other hand, as shown in Figures 6 and 7, when the positional deviation of the subject's eye E exceeds the specified range, the subject will see a fixation target FP that is partially vignetted depending on the direction and amount of deviation of the positional deviation of the subject's eye E. In this case, the subject will recognize the need for the above-mentioned rough alignment and will be able to recognize the direction in which the fixation target FP is vignetted in the up, down, left, and right directions. Based on this vignetting direction, the subject can determine the direction in which to move the subject's eye E (face). This allows the subject to perform rough alignment, adjusting the position of the subject's eye E (face) so that the cross-shaped fixation target FP is not partially vignetted, i.e., so that the lengths of the cross-shaped fixation target FP appear equal in the up, down, left, and right directions. As a result, the positional deviation of the subject's eye E is kept within the specified range, so that the subject's eye E can be placed within the alignment detection range or observation range even if the pupil diameter of the subject's eye E is large, enabling alignment detection and observation of the subject's eye E.

[0066] [Control device] The control device 100 includes an arithmetic circuit configured with various processors, memories, etc., and controls the overall operation of each part of the slit lamp microscope 10 based on operation instructions from the examiner input to an operation unit (not shown). The control device 100 controls the projection of fixation light LF onto the subject's eye E by the fixation optical system 80, alignment detection and alignment of the Scheimpflug optical system 12 with respect to the subject's eye E, irradiation of the anterior segment Ea with slit light LS by the illumination system 20 and capture of anterior segment cross-sectional images DR and DL by the imaging systems 30R and 30L, scanning of the anterior segment Ea with the slit light LS, and generation of a three-dimensional image of the anterior segment Ea.

[0067] The control device 100 controls the fixation light source 81 to cause the fixation optical system 80 to project fixation light LF onto the fundus Ef in a state before the start of alignment of the Scheimpflug optical system 12 with the subject's eye E, such as when the slit lamp microscope 10 is powered on. Furthermore, while the anterior segment Ea is being scanned with the slit light LS, the control device 100 controls the fixation light source 81 to cause the fixation optical system 80 to project fixation light LF onto the fundus Ef.

[0068] Furthermore, when the control device 100 receives an instruction to generate a three-dimensional image of the anterior eye segment Ea via an operation unit (not shown), it controls the observation system 50 (or the imaging systems 30R and 30L) to capture an observation image D of the anterior eye segment Ea, and performs alignment detection to detect the relative position of the subject's eye E with respect to the Scheimpflug optical system 12 based on the observation image D. Then, based on the result of the alignment detection, the control device 100 drives the movement mechanism 14 to adjust the XYZ direction position of the Scheimpflug optical system 12, thereby performing alignment (precise alignment) in the XYZ directions of the Scheimpflug optical system 12 with respect to the subject's eye E. Note that alignment detection and alignment are well-known techniques, and detailed description thereof will be omitted here.

[0069] Furthermore, when the above-mentioned alignment is completed, the control device 100 causes the illumination system 20 to irradiate the anterior eye segment Ea with slit light LS, the imaging systems 30R and 30L to capture cross-sectional images of the anterior eye segment Ea, and the moving mechanism 14 to scan the slit light LS in the X direction (see Patent Document 1 above).The control device 100 then generates a three-dimensional image of the anterior eye segment Ea by a known method based on the anterior eye segment cross-sectional images DR and DL captured by the imaging systems 30R and 30L at each scanning position during the scanning of the slit light LS (see Patent Document 1 above).

[0070] [Slit lamp microscope function] 8 is a flowchart showing the flow of the process of generating a three-dimensional image of the anterior eye segment Ea using the slit lamp microscope 10 configured as described above. Note that the following description will be given taking a screenoscope-type slit lamp microscope 10 as an example.

[0071] 8, when the slit lamp microscope 10 is powered on, the control device 100 controls the fixation light source 81 to start emitting fixation light LF from the fixation light source 81. When the subject looks into an eyepiece (not shown) of the slit lamp microscope 10, the fixation light LF is projected from the fixation optical system 80 onto the fundus Ef, and a cross-shaped fixation target FP is presented to the subject (step S1). This allows the subject to recognize whether rough alignment, which is a position adjustment of the subject's eye E (face), is necessary or unnecessary, based on whether the entire cross-shaped fixation target FP is visible.

[0072] If a part of the fixation target FP is vignetted according to the direction and amount of positional misalignment of the subject's eye E, the subject determines the direction in which to move the subject's eye E (face) based on the direction in which the fixation target FP is vignetted among the up, down, left, and right directions.The subject then performs rough alignment to adjust the position of the subject's eye E so that the lengths of the fixation target FP in the up, down, left, and right directions appear equal (step S2).This brings the positional misalignment of the subject's eye E within a specified range, making it possible to detect alignment and observe the subject's eye E.

[0073] Next, when the examiner operates an operation unit (not shown) to start generating a three-dimensional image of the anterior eye segment Ea, the control device 100 causes the observation system 50 to capture an image of the anterior eye segment Ea, and detects the alignment of the subject's eye E with respect to the Scheimpflug optical system 12 based on the observation image D (anterior eye segment image) obtained by this capture. Then, based on the alignment detection result, the control device 100 drives the moving mechanism 14 to align the Scheimpflug optical system 12 (step S3). As a result, the Scheimpflug optical system 12 is positioned at the scanning start position of the slit light LS with respect to the anterior eye segment Ea.

[0074] When the alignment is completed, the control device 100 starts irradiating the anterior segment Ea with the slit light LS from the illumination system 20 (step S4) and also causes the image pickup elements 34R and 34L of the imaging systems 30R and 30L to capture the returned light LA, i.e., to capture a cross-section of the anterior segment Ea (step S5). As a result, the image pickup elements 34R and 34L output the anterior segment cross-sectional images DR and DL to the control device 100.

[0075] Then, the control device 100 starts scanning the anterior eye segment Ea with the slit light LS by driving the moving mechanism 14 to move the Scheimpflug optical system 12 in the X direction (step S6). As a result, while the slit light LS is scanning in the X direction, the imaging systems 30R, 30L capture anterior eye segment cross-sectional images DR, DL at each scanning position in the X direction of the slit light LS, and the control device 100 acquires the anterior eye segment cross-sectional images DR, DL from the imaging systems 30R, 30L (step S7).

[0076] Furthermore, the control device 100 projects fixation light LF from the fixation optical system 80 onto the fundus oculi Ef in synchronization with the start of scanning of the anterior segment Ea with the slit light LS (step S8). This presents a fixation target FP to the subject's eye E, so that the subject's line of sight can be fixed in the direction of the fixation target FP, i.e., the subject can fixate the eye E. As a result, the subject is prevented from following the slit light LS with his or her eyes when the anterior segment Ea is scanned with the slit light LS.

[0077] The processes from step S6 to step S8 are repeated until the slit light LS reaches the scanning end position (NO in step S9). When the scanning of the anterior eye segment Ea by the slit light LS is completed (YES in step S9), the control device 100 generates a 3D image of the anterior eye segment Ea based on the anterior eye segment cross-sectional images DR and DL for each scanning position of the slit light LS acquired from the imaging systems 30R and 30L (step S10).

[0078] As described above, in this embodiment, by providing the fixation optical system 80 in the observation system 50 whose relative position with respect to the subject's eye E is fixed, while the Scheimpflug optical system 12 is being moved in the X direction, i.e., while the anterior segment Ea is being scanned with the slit light LS, the fixation optical system 80 can fixate the subject's eye E, thereby fixing the line of sight of the subject's eye E. As a result, a good three-dimensional image of the anterior segment Ea can be obtained.

[0079] [Modification of observation system] 9 is an explanatory diagram illustrating a modified example of the observation system 50 of the slit lamp microscope 10. In the above embodiment, the observation system 50 guides the return light LB to the image sensor 54, but the return light LB may be guided to an eyepiece 59, that is, the examiner may observe the observation image D (anterior eye image) through the eyepiece 59. In this case, as shown in FIG. 9, an eyepiece system 56 is provided in the observation system 50. This eyepiece system 56 includes a beam splitter 57, an imaging lens 58, and the eyepiece 59.

[0080] The beam splitter 57 is disposed on the observation optical axis O3, and transmits a portion of the return light LB from the subject's eye E to the optical system 52, and reflects the remainder toward the imaging lens 58. The imaging lens 58 guides the return light LB incident from the beam splitter 57 to the eyepiece 59. This allows the examiner to observe the observation image D through the eyepiece 59.

[0081] [others] In the above embodiment, the slit light LS parallel to the YZ plane is scanned in the X direction by moving the Scheimpflug optical system 12 in the X direction using the moving mechanism 14, but the length direction and scanning direction of the slit light LS can be changed as desired. Furthermore, as described in Patent Document 1, the anterior segment Ea may be scanned with the slit light LS by rotating the Scheimpflug optical system 12 about the illumination optical axis O1.

[0082] In the above embodiment, the anterior segment Ea is irradiated with the slit light LS, but the irradiation position of the slit light LS may be changed as appropriate within the subject's eye E. Also, in the above embodiment, the subject's eye E is irradiated with the slit light LS, but the subject's eye E may be irradiated with illumination light of various shapes other than the slit light LS.

[0083] In the above embodiment, the Scheimpflug optical system 12 is provided with two imaging systems 30R and 30L, but the number of imaging systems may be one or three or more.

[0084] In the above embodiment, a cross-shaped fixation light LF is projected from the fixation optical system 80 onto the fundus Ef, but the shape of the fixation light LF is not particularly limited as long as the subject can recognize the positional deviation of the subject's eye E (preferably the direction and amount of deviation).For example, fixation light LF of various shapes, such as radial shapes extending in a total of eight directions (up, down, left, right, and diagonally), or concentric circles, may be projected onto the fundus Ef. [Explanation of symbols]

[0085] 10. Slit Lamp Microscope 12 Scheimpflug optics 14 Moving mechanism 20 Lighting System 22 Light source 24 Slit forming section 26 Objective Lens 30L, 30R photography system 32L,32R optical system 34L, 34R image sensor 36L, 36R imaging surface 50 Observation System 52 Optical system 54 Image sensor 56 Eyepiece system 57 Beam Splitter 58 Imaging Lens 59 Eyepiece 80 Fixation optical system 81 Fixation light source 82 Diffuser 83 Pinhole material 83a Pinhole 84 Lens 85 Crosshair reticle plate 86 Lens 87 Mirror 100 control device C. Dotted circle D Observation image DL,DR Anterior segment cross-sectional image Df fundus image E. Examined eye Ea anterior segment Ef fundus FP fixation target H1 plane H2L,H2R plane H3L,H3R plane L illumination light LA,LB Return light LF fixation light LS slit light O1 Lighting optical axis O2L, O2R Shooting optical axis O3 Observation optical axis O4 Projection optical axis SL,SR main surface SP material θ Tilt angle θL angle θR angle φ Luminous flux diameter

Claims

1. an illumination system having an illumination optical axis and irradiating the subject's eye with illumination light along the illumination optical axis; an imaging system including a first image sensor and an optical system that guides return light from the subject's eye illuminated with the illumination light to an imaging surface of the first image sensor, and that captures an image of the return light using the first image sensor; a relative movement mechanism that moves a Scheimpflug optical system including the illumination system and the imaging system relative to the eye to scan the eye with the illumination light; Equipped with In a microscope, an object plane including the illumination optical axis, a principal plane of the optical system, and the imaging plane satisfy the Scheimpflug condition, a fixation optical system whose relative position with respect to the subject's eye is fixed, which has a projection optical axis different from the illumination optical axis and an imaging optical axis of the imaging system, and which projects fixation light onto the subject's eye along the projection optical axis; the fixation optical system projects the fixation light onto the subject's eye at least while the relative movement mechanism is performing relative movement of the Scheimpflug optical system; A microscope comprising an observation system whose relative position with respect to the subject's eye is fixed, and which has an observation optical axis that is different from the illumination optical axis and the photographing optical axis and is common with a part of the projection optical axis, and which guides return light from the subject's eye that is incident along the observation optical axis to a second image sensor or an eyepiece.

2. 2. The microscope according to claim 1, wherein the shape and beam diameter of the fixation light projected by the fixation optical system onto the subject's eye are set so that when a positional deviation of the subject's eye from a predetermined assumed position of the subject's eye is within a predetermined specified range, the entire fixation light is projected onto the subject's eye, and when the positional deviation exceeds the specified range, the shape and beam diameter of the fixation light are set so that the fixation light is vignetted according to the direction and amount of the positional deviation.

3. An illumination system having an illumination optical axis and irradiating illumination light onto the subject's eye along the illumination optical axis; an imaging system including a first image sensor and an optical system that guides return light from the subject's eye illuminated with the illumination light to an imaging surface of the first image sensor, and that captures an image of the return light using the first image sensor; a relative movement mechanism that moves a Scheimpflug optical system including the illumination system and the imaging system relative to the eye to scan the eye with the illumination light; Equipped with In a microscope, an object plane including the illumination optical axis, a principal plane of the optical system, and the imaging plane satisfy the Scheimpflug condition, a fixation optical system whose relative position with respect to the subject's eye is fixed, which has a projection optical axis different from the illumination optical axis and an imaging optical axis of the imaging system, and which projects fixation light onto the subject's eye along the projection optical axis; the fixation optical system projects the fixation light onto the subject's eye at least while the relative movement mechanism is performing relative movement of the Scheimpflug optical system; A microscope in which the shape and beam diameter of the fixation light projected by the fixation optical system onto the subject's eye are set so that when the positional deviation of the subject's eye from a predetermined assumed position of the subject's eye is within a predetermined specified range, the entire fixation light is projected onto the subject's eye, and when the positional deviation exceeds the specified range, the shape and beam diameter of the fixation light are set so that the fixation light is vignetted depending on the direction and amount of the positional deviation.

4. 4. The microscope according to claim 2, wherein the shape of the fixation light is a cross.

5. 5. The microscope according to claim 3, further comprising an observation system whose relative position with respect to the subject's eye is fixed, which has a common observation optical axis with a part of the projection optical axis, and which guides return light from the subject's eye that is incident along the observation optical axis to a second image sensor or an eyepiece.

6. 6. The microscope according to claim 1, wherein the fixation optical system projects the fixation light onto the subject's eye through a pinhole.

7. When a direction parallel to the illumination optical axis is defined as a Z direction among X, Y, and Z directions which are orthogonal to each other, the imaging optical axis is perpendicular to a Y direction and is inclined with respect to the illumination optical axis when viewed from the Y direction, 7. The microscope according to claim 1, wherein the projection optical axis overlaps with the illumination optical axis when viewed from the Y direction and is tilted with respect to the illumination optical axis when viewed from the X direction.

8. the illumination system irradiates an anterior segment of the subject's eye with slit-shaped illumination light parallel to the object plane, 8. The microscope according to claim 1, wherein the relative movement mechanism moves the Scheimpflug optical system in a direction perpendicular to the object plane.

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