Non-contact tonometry device, alignment method, and program

Abstract

To properly align a non-contact tonometry device in a Z direction without increase in the number of components.SOLUTION: An ophthalmologic apparatus 1 comprises a first optical system, a second optical system, a drive unit 4, and a control unit 80. The drive unit 4 relatively displaces the ophthalmologic apparatus 1 in a Z direction that is a direction along an inspection axis IO relative to a subject eye E. The control unit 80 controls the drive unit 4 to execute a first alignment in the Z direction based on first illumination light received by an anterior eye part imaging unit 35. Thereafter, the control unit 80 controls the drive unit 4 to execute a second alignment in the Z direction based on second illumination light received by a second imaging element 77.SELECTED DRAWING: Figure 12

Description

[Technical Field]

[0001] The present disclosure relates to a non-contact tonometry device for measuring the intraocular pressure of a subject's eye, a method for aligning the non-contact tonometry device, and a program for executing the alignment of the non-contact tonometry device. [Background technology]

[0002] There is known a non-contact tonometry device that measures the intraocular pressure of a subject's eye by deforming the cornea of ​​the subject's eye and detecting the deformed cornea. When measuring intraocular pressure using such a non-contact tonometry device, it is necessary to precisely adjust the position of the device relative to the subject's eye. For example, the ophthalmic apparatus described in Patent Document 1 has a working distance detection optical system for performing alignment in a direction parallel to the examination axis (Z direction). Then, alignment of the ophthalmic apparatus in the Z direction is performed based on a detection signal from a position detection element of the working distance detection optical system. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-76390 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the ophthalmic apparatus of Patent Document 1 includes a dedicated working distance detection optical system for performing alignment in the Z direction, which increases the number of parts and increases the cost of the product.

[0005] A typical object of the present disclosure is to provide a non-contact intraocular pressure measuring device, an alignment method, and a program that are capable of performing alignment in the Z direction without providing a dedicated alignment optical system. [Means for solving the problem]

[0006] A non-contact ocular pressure measurement device provided by a typical embodiment of the present disclosure is a non-contact ocular pressure measurement device that detects deformation of the cornea of ​​a test eye and measures the ocular pressure of the test eye while an examination axis is aligned with the cornea of ​​the test eye, and includes: a first optical system that irradiates the test eye with first irradiation light including at least parallel light; a second optical system that irradiates the test eye with second irradiation light that is focused on the cornea of ​​the test eye in order to measure the corneal thickness of the cornea of ​​the test eye; a drive unit that moves the non-contact ocular pressure measurement device relatively to the test eye in a Z direction that is a direction along the examination axis; and a control unit; a first optical system including a first light source that emits light and a first image sensor that receives the first irradiation light reflected by the cornea of ​​the test eye; a second optical system including a second light source that emits light and a second image sensor that receives the second irradiation light reflected by the cornea of ​​the test eye; and a control unit that causes the drive unit to perform a first alignment in the Z direction based on the first irradiation light received by the first image sensor, and then causes the drive unit to perform a second alignment in the Z direction based on the second irradiation light received by the second image sensor.

[0007] An alignment method provided by a typical embodiment of the present disclosure is a method for aligning a non-contact tonometry device that measures intraocular pressure of a subject eye by detecting deformation of the cornea of ​​the subject eye while aligning an examination axis with the cornea of ​​the subject eye, the method including the steps of: irradiating the subject eye with first irradiation light including at least parallel light; receiving the first irradiation light reflected by the subject eye with a first image sensor; irradiating the subject eye with second irradiation light that is focused on the cornea of ​​the subject eye in order to measure the corneal thickness of the cornea of ​​the subject eye; the second illumination light emitted from the first imaging element is received by a second imaging element, and a first alignment is performed based on the first illumination light received by the first imaging element to move the non-contact ocular pressure measurement device relative to the subject's eye in a Z direction that is a direction along the examination axis, and after performing the first alignment, a second alignment is performed based on the second illumination light received by the second imaging element to move the non-contact ocular pressure measurement device relative to the subject's eye in the Z direction.

[0008] A typical embodiment of the present disclosure provides a program for performing alignment of a non-contact ocular pressure measurement device that detects deformation of the cornea of ​​a test eye and measures the intraocular pressure of the test eye while aligning an examination axis with the cornea of ​​the test eye, the program causing a processor of the non-contact ocular pressure measurement device to perform a first alignment to move the non-contact ocular pressure measurement device relative to the test eye in a Z direction, which is a direction along the examination axis, based on first irradiation light that includes at least parallel light and is reflected by the test eye and received by a first image sensor, and to perform a second alignment to move the non-contact ocular pressure measurement device relative to the test eye in the Z direction, after performing the first alignment, based on second irradiation light that is focused on the cornea of ​​the test eye in order to measure the corneal thickness of the cornea of ​​the test eye and is reflected by the cornea of ​​the test eye and received by a second image sensor.

[0009] The non-contact intraocular pressure measuring device, alignment method, and program according to the present disclosure can perform alignment in the Z direction with high precision without increasing the number of parts. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 2 is a left side view showing the external configuration of the ophthalmologic apparatus. [Figure 2] FIG. 2 is a diagram illustrating an internal configuration of an ophthalmologic apparatus. [Figure 3] FIG. 1 is a diagram illustrating an optical system of an ophthalmic apparatus. [Figure 4] FIG. 10 is a diagram showing an anterior segment image before the alignment in the Z direction is completed. [Figure 5] FIG. 10 is a diagram showing an anterior eye image after Z-direction alignment is completed. [Figure 6] 10 is a graph showing the relationship between the amount of deviation and the ratio between bright spots for different corneal curvature radii. [Figure 7] 10 is a graph showing the relationship between the radius of curvature of the cornea and the amount of deviation. [Figure 8] 10A and 10B are diagrams showing measurement images of corneas having different radii of curvature when the ratio between bright spots reaches the reference ratio. [Figure 9] 10 is a graph showing the relationship between the radius of curvature of the cornea and the collimated bright spot interval. [Figure 10] 1 is a diagram schematically illustrating an optical system in a state where the center of a measurement area coincides with an inspection axis. [Figure 11] 1 is a diagram schematically illustrating an optical system in a state where the center of a measurement area is shifted from an inspection axis. [Figure 12] 10 is a flowchart illustrating a process executed by an ophthalmologic apparatus. [Figure 13] 10 is a flowchart showing a first alignment process. [Figure 14] 10 is a flowchart showing a first rough alignment process. [Figure 15] 10 is a flowchart showing a second rough alignment process. [Figure 16] 10 is a flowchart showing a third rough alignment process. [Figure 17] 10 is a flowchart showing a second alignment process. [Figure 18] FIG. 10 is a diagram showing an optical system of an ophthalmic apparatus according to a second embodiment. [Figure 19] 10A and 10B are diagrams illustrating positions of bright points on deformation detection images when the ophthalmologic apparatus is positioned differently. [Figure 20] FIG. 10 is a schematic diagram showing an optical system of an ophthalmologic apparatus according to a third embodiment. [Figure 21] FIG. 10 is a comparative diagram showing the bright spot positions of measurement light and alignment light. DETAILED DESCRIPTION OF THE INVENTION

[0011] <Summary> A non-contact ocular pressure measurement device exemplified in the present disclosure measures the intraocular pressure of a subject eye by detecting deformation of the cornea of ​​the subject eye with an examination axis aligned with the cornea. The non-contact ocular pressure measurement device includes a first optical system, a second optical system, a drive unit, and a control unit. The first optical system irradiates the subject eye with first irradiation light including at least parallel light. The second optical system irradiates the subject eye with second irradiation light that is focused on the cornea of ​​the subject eye to measure the corneal thickness of the cornea of ​​the subject eye. The drive unit moves the non-contact ocular pressure measurement device relative to the subject eye in the Z direction, which is a direction along the examination axis. The first optical system includes a first light source that emits light and a first image sensor that receives the first irradiation light reflected by the cornea of ​​the subject eye. The second optical system includes a second light source that emits light and a second image sensor that receives the second irradiation light reflected by the cornea of ​​the subject eye. The control unit causes the driving unit to perform a first alignment in the Z direction based on the first irradiation light received by the first imaging element, and then causes the driving unit to perform a second alignment in the Z direction based on the second irradiation light received by the second imaging element.

[0012] The control unit causes the drive unit to perform a first alignment based on the first irradiation light received by the first imaging element. The first irradiation light includes at least parallel light. Therefore, in the first alignment, rough alignment in the Z direction can be performed for the non-contact tonometry device using reflected parallel light. Thereafter, the control unit causes the drive unit to perform a second alignment based on the second irradiation light received by the second imaging element. The second alignment is performed based on the reception result of the second irradiation light focused on the cornea of ​​the test eye. Therefore, in the second alignment, precise alignment in the Z direction can be performed for the non-contact tonometry device.

[0013] The first optical system may be configured to form collimated bright spots by collimated light and non-collimated bright spots by non-collimated light on a two-dimensional image captured by the first imaging element, and the control unit may cause the drive unit to perform the first alignment based on the collimated bright spots and non-collimated bright spots formed on the two-dimensional image.

[0014] In this case, the first optical system is configured to form collimated and non-collimated bright spots on the two-dimensional image captured by the first imaging element. The collimated bright spots have the property that their position and shape are unlikely to change regardless of the position of the non-contact tonometry device in the Z direction. On the other hand, at least one of the position and shape of the non-collimated bright spots changes depending on the position of the non-contact tonometry device in the Z direction. By utilizing these properties, the first alignment can be performed based on the collimated and non-collimated bright spots.

[0015] The first optical system may be configured to form a pair of collimated bright spots and a pair of non-collimated bright spots on the two-dimensional image, and the control unit may cause the drive unit to perform the first alignment based on the spacing between the pair of collimated bright spots and the spacing between the pair of non-collimated bright spots.

[0016] The distance between a pair of collimated bright spots formed by collimated light tends to be constant regardless of the position of the non-contact tonometry device in the Z direction. On the other hand, the distance between a pair of non-collimated bright spots formed by non-collimated light varies depending on the position of the non-contact tonometry device in the Z direction. Utilizing these characteristics, the first alignment can be appropriately performed based on the distance between the two collimated bright spots and the distance between the two non-collimated bright spots.

[0017] However, the manner in which the first alignment is performed is not limited to this. For example, the first optical system may be configured to form a pair of collimated bright spots formed by collimated light and one ring-shaped bright spot formed by non-collimated light on the two-dimensional image. The control unit may then cause the driving unit to perform the first alignment based on the distance between the pair of collimated bright spots and the diameter of the ring-shaped bright spot. The first optical system may also be configured to form one collimated bright spot formed by collimated light and one non-collimated bright spot formed by non-collimated light on the two-dimensional image. The control unit may then cause the driving unit to perform the first alignment based on the positional relationship between the one collimated bright spot and the one non-collimated bright spot.

[0018] The control unit may change the timing of transition from the first alignment to the second alignment depending on the radius of curvature of the cornea of ​​the subject's eye.

[0019] In this case, the control unit changes the timing of transition from the first alignment to the second alignment depending on the radius of curvature of the cornea of ​​each subject eye, so that the transition from the first alignment to the second alignment can be made at an appropriate timing depending on the radius of curvature of the cornea of ​​the subject eye.

[0020] In addition, the control unit may calculate a reference value based on the first irradiation light while performing the first alignment, and may determine the timing to transition from the first alignment to the second alignment based on the calculated reference value.

[0021] In this case, the control unit calculates a reference value based on the first irradiation light while performing the first alignment. Then, based on the calculated reference value, the control unit determines the timing to transition from the first alignment to the second alignment. That is, the control unit determines the timing to transition from the first alignment to the second alignment taking into account the reference value based on the first irradiation light in addition to the radius of curvature of the cornea of ​​the test eye. Therefore, the control unit can more appropriately determine the timing to transition from the first alignment to the second alignment.

[0022] The control unit may estimate the radius of curvature of the test cornea based on a bright spot formed by the first irradiation light on the two-dimensional image captured by the first imaging element.

[0023] In this case, the radius of curvature of the cornea of ​​the test eye is estimated based on the bright spot formed by the first irradiation light, which eliminates the need for a separate mechanism for measuring the radius of curvature, thereby reducing the cost of the non-contact ocular pressure measurement device.

[0024] In addition, the control unit may stop the second alignment by the driving unit if, while causing the driving unit to perform the second alignment, the center of the measurement area of ​​the test eye becomes more than a predetermined distance away from the examination axis of the test eye and the second imaging element detects the second irradiation light reflected by something other than the cornea of ​​the test eye of the test subject.

[0025] In this case, the control unit determines whether the center of the measurement area of ​​the test eye has deviated from the test axis by a predetermined distance or more during the second alignment. Then, if the center of the measurement area is deviated from the test axis by a predetermined distance or more and the second image sensor detects the second irradiation light reflected by a part other than the cornea of ​​the test eye, the control unit causes the drive unit to stop the second alignment. Therefore, inaccurate alignment based on the second irradiation light when the test eye has deviated from the test axis can be stopped. Furthermore, the control unit sets the detection of the second irradiation light by the second image sensor as a condition for stopping the second alignment. Therefore, even if the center of the measurement area is deviated from the test axis, the second alignment can be continued without being stopped as long as a bright spot reflected by the cornea is detected.

[0026] Furthermore, the control unit may stop the second alignment by the driving unit if, while the driving unit is performing the second alignment, a bright spot caused by the first irradiation light is no longer formed on the two-dimensional image captured by the first imaging element, and if the second imaging element detects the second irradiation light reflected from somewhere other than the subject's test cornea.

[0027] In this case, if the subject closes their eyes and the bright spot caused by the first irradiation light no longer appears on the two-dimensional image captured by the first imaging element, and the second imaging element detects the second irradiation light reflected from a location other than the cornea of ​​the subject's eye, the second alignment is stopped. Therefore, for example, if the subject's eyelids are closed, inaccurate alignment based on the second irradiation light reflected from the eyelids can be stopped. Furthermore, the control unit sets the detection of the second irradiation light by the second imaging element as a condition for stopping the second alignment. Therefore, if the subject only closes their pupils for a moment, then opens their eyes and detects the bright spot reflected from the cornea, the second alignment can be continued without being stopped.

[0028] Furthermore, if the position in the Z direction relative to the test eye of the non-contact ocular pressure measurement device is defined as the measurement position where the corneal thickness of the test eye's cornea is measured, the control unit may cause the drive unit to end the second alignment when the Z direction position of the non-contact ocular pressure measurement device reaches the measurement position while causing the drive unit to perform the second alignment, and measure the corneal thickness of the test eye's cornea based on the second irradiation light reflected by the test eye's cornea and received by the second image sensor.

[0029] In this case, when the position of the non-contact tonometry device in the Z direction reaches the measurement position during the second alignment, the control unit ends the second alignment and transitions to corneal thickness measurement. Therefore, once the alignment in the Z direction is completed, it is possible to automatically shift to corneal thickness measurement.

[0030] The first optical system may be a detection optical system that obliquely irradiates the cornea of ​​the test eye with first irradiation light and detects deformation of the cornea of ​​the test eye based on the first irradiation light reflected by the cornea of ​​the test eye and received by a first image sensor. The control unit may cause the drive unit to perform the first alignment based on the first irradiation light reflected by the cornea of ​​the test eye and received by the first image sensor.

[0031] A detection optical system that detects corneal deformation of the cornea of ​​the test eye can be used as the first optical system for performing the first alignment. Therefore, there is no need to provide a separate light source or image sensor for performing alignment in the Z direction. This reduces the number of parts and the cost of the non-contact ocular pressure measurement device.

[0032] Furthermore, the first optical system may be an alignment optical system that obliquely irradiates the test cornea with the first irradiation light.The second optical system may be configured so that the second light source is provided on the same side as the first light source with respect to the examination axis of the non-contact tonometry device, and the second irradiation light is irradiated onto the test cornea in a state where the optical axis of the first irradiation light is coaxial with that of the first irradiation light.Furthermore, the first imaging element and the second imaging element may be the same imaging element that is provided on the opposite side of the examination axis from the first light source and the second light source and is capable of receiving the first irradiation light and the second irradiation light.

[0033] The first and second imaging elements can be the same imaging element capable of receiving the first irradiation light and the second irradiation light. This eliminates the need to provide a separate imaging element for performing the first alignment. This reduces the cost of the non-contact ocular pressure measurement device.

[0034] The alignment method exemplified in the present disclosure is a method for aligning a non-contact tonometry device that measures the intraocular pressure of a test eye by detecting deformation of the cornea of ​​the test eye while aligning an examination axis with the cornea of ​​the test eye. The alignment method includes irradiating the test eye with first irradiation light including at least parallel light, and receiving the first irradiation light reflected from the test eye with a first image sensor. The alignment method also includes irradiating the test eye with second irradiation light that is focused on the test cornea to measure the corneal thickness of the test eye, and receiving the second irradiation light reflected from the cornea of ​​the test eye with a second image sensor. Based on the first irradiation light received by the first image sensor, a first alignment is performed to move the non-contact tonometry device relative to the test eye in the Z direction, which is the direction along the examination axis. After the first alignment, a second alignment is performed to move the non-contact tonometry device relative to the test eye in the Z direction based on the second irradiation light received by the second image sensor.

[0035] A first alignment is performed on the non-contact tonometry device based on the first irradiation light including parallel light received by the first image sensor. Therefore, in the first alignment, rough alignment in the Z direction can be performed on the non-contact tonometry device using reflected parallel light. Thereafter, a second alignment is performed on the non-contact tonometry device based on the second irradiation light received by the second image sensor. The second alignment is performed based on the reception result of the second irradiation light focused on the cornea of ​​the test eye. Therefore, in the second alignment, precise alignment in the Z direction can be performed on the non-contact tonometry device.

[0036] In addition, collimated light and non-collimated light may be irradiated onto the test eye as first irradiation light, and the first alignment may be performed based on the collimated bright spot formed by the collimated light and the non-collimated bright spot formed by the non-collimated light on the two-dimensional image captured by the first imaging element.

[0037] The collimated bright spot has the property that its position or shape does not change regardless of the position of the non-contact tonometry device in the Z direction. On the other hand, the position or shape of the non-collimated bright spot changes depending on the position of the non-contact tonometry device in the Z direction. By utilizing these properties, a first alignment can be performed based on the collimated bright spot and the non-collimated bright spot.

[0038] A program exemplified in the present disclosure is a program for executing alignment of a non-contact tonometry device that measures the intraocular pressure of a test eye by detecting deformation of the cornea of ​​the test eye while aligning an examination axis with the cornea of ​​the test eye. The program causes a processor of the non-contact tonometry device to execute first alignment, in which the non-contact tonometry device moves relative to the test eye in the Z direction, which is a direction along the examination axis, based on first irradiation light including at least parallel light, which is reflected by the test eye and received by a first image sensor. The program then causes a processor of the non-contact tonometry device to execute second alignment, in which the non-contact tonometry device moves relative to the test eye in the Z direction, based on second irradiation light, which is focused on the test cornea to measure the corneal thickness of the test eye, which is reflected by the test cornea and received by a second image sensor.

[0039] The processor is caused to perform a first alignment of the non-contact tonometry device based on the first irradiation light including parallel light received by the first imaging element. Therefore, in the first alignment, rough alignment in the Z direction of the non-contact tonometry device can be performed using reflected parallel light. Thereafter, the processor is caused to perform a second alignment of the non-contact tonometry device based on the second irradiation light received by the second imaging element. The second alignment is performed based on the reception result of the second irradiation light focused on the cornea of ​​the test eye. Therefore, in the second alignment, precise alignment in the Z direction of the non-contact tonometry device can be performed.

[0040] The processor may also be configured to perform a first alignment based on collimated and non-collimated bright spots formed, respectively, on a two-dimensional image captured by the first imaging element using collimated and non-collimated light irradiated onto the test eye as first irradiation light.

[0041] The collimated bright spot has the property that its position or shape does not change regardless of the position of the non-contact tonometry device in the Z direction. On the other hand, the position or shape of the non-collimated bright spot changes depending on the position of the non-contact tonometry device in the Z direction. By utilizing these properties, a first alignment can be performed based on the collimated bright spot and the non-collimated bright spot.

[0042] <Embodiment> Hereinafter, one typical embodiment (first embodiment) according to the present disclosure will be described with reference to the drawings. An ophthalmic apparatus 1 examines a subject's eye (examined eye) E with an examination axis IO aligned with the subject's eye (examined eye) E. The ophthalmic apparatus 1 illustrated in this embodiment is equipped with an examination protrusion 9 that protrudes toward the examinee's eye along the examination axis IO, and measures the intraocular pressure of the examinee's eye E from the deformed shape of the cornea Ec by spraying fluid from the examination protrusion 9 onto the cornea Ec of the examinee's eye E. In other words, the ophthalmic apparatus 1 illustrated in this embodiment is a non-contact intraocular pressure measuring device. In this disclosure, "examination" includes both measurement and photography of the examinee's eye E.

[0043] The schematic configuration of an ophthalmic apparatus 1 will be described with reference to FIG. 1. In the following description, the left-right direction of the paper in FIG. 1 is the Z direction (front-back direction), the up-down direction of the paper is the Y direction (up-down direction), and the depth direction of the paper is the X direction (left-right direction). The examination axis IO is parallel to the Z direction and perpendicular to the XY plane. In detail, the left side of the paper (subject side) in FIG. 1 is the front side of the ophthalmic apparatus 1, and the right side of the paper is the rear side of the ophthalmic apparatus 1. The upper side of the paper in FIG. 1 is the upper side of the ophthalmic apparatus 1, and the lower side of the paper is the lower side of the ophthalmic apparatus 1. The front side of the paper in FIG. 1 is the left side of the ophthalmic apparatus 1, and the depth side of the paper is the right side of the ophthalmic apparatus 1. The Z direction is parallel to the examination axis IO.

[0044] As shown in FIG. 1, the ophthalmologic apparatus 1 of this embodiment includes a base 2, a housing 3, a drive unit 4, and a face support unit 5. The base 2 is placed at an installation location and supports the entire ophthalmologic apparatus 1. The housing 3 includes various components for performing an examination of the subject's eye E (details will be described later). The housing 3 is supported on the base 2 via the drive unit 4. The face support unit 5 supports and positions the subject's face. In this embodiment, a chin rest and a forehead rest are used as the face support unit 5. The subject places their chin on the chin rest and their forehead on the forehead rest, thereby positioning the face. The drive unit 4 moves the position of the housing 3 relative to the subject's face, which has been positioned by the face support unit 5.

[0045] As an example, the drive unit 4 of this embodiment moves the housing 3 in the front-back, up-down, and left-right directions (three-dimensional directions) relative to the base 2 using an actuator 4a (see FIG. 2 ), such as a motor. This moves the position of the housing 3 relative to the face (or the eye) of the subject. However, the configuration of the drive unit 4 can be changed. For example, the drive unit 4 may move the position of the housing 3 relative to the face of the subject by moving the face support unit 5. Alternatively, the drive unit 4 may move both the housing 3 and the face support unit 5. For example, the drive unit 4 may move the housing 3 in the front-back and left-right directions and also move the face support unit 5 in the up-down direction to move the position of the housing 3 relative to the face of the subject. The actuator 4a of the drive unit 4 is operated and controlled by a control unit 80, which will be described later.

[0046] The housing 3 includes an examination protrusion (nozzle) 9, a face capturing unit 12, a display unit 7, and an operation unit 8. The housing 3 includes a surface 3a facing the eye to be examined, which is the side on which the subject's face is positioned (in this embodiment, the front side facing the eye to be examined). The examination protrusion 9 protrudes from the surface 3a facing the eye to be examined along an examination axis IO toward the eye to be examined. The examination axis IO is aligned with the eye to be examined E when the examination is performed. As an example, the examination protrusion 9 in this embodiment is a nozzle that sprays a fluid (e.g., compressed air) onto the cornea of ​​the eye to be examined. However, the specific configuration of the examination protrusion can be appropriately selected depending on the type of examination performed by the ophthalmologic apparatus. For example, an attachment that is detachably attached to the housing 3 to change the imaging angle of view, a protrusion that emits light or ultrasound for examination from its tip toward the eye to be examined E, or the like may be used as the examination protrusion.

[0047] The face photographing unit 12 photographs the face of the subject. The display unit 7 displays various images. In this embodiment, the display unit 7 is disposed on the rear side of the housing 3 facing the examiner. Various operation instructions are input to the operation unit 8 by the user. As an example, in this embodiment, a touch panel installed on the display surface of the display unit 7 is used as the operation unit 8. However, at least one of a joystick, a mouse, a keyboard, a drag ball, a button, a remote controller, etc. may also be used as the operation unit 8.

[0048] The internal configuration of the ophthalmic apparatus 1 will be described with reference to Fig. 2. The ophthalmic apparatus 1 includes a measurement optical system 10, a fluid discharge unit 20, and a control unit (control unit) 80. The measurement optical system 10 and the fluid discharge unit 20 are an example of an examination unit that performs an examination of the subject's eye E. As described above, the examination unit of this embodiment measures the intraocular pressure of the subject's eye E in a non-contact manner. Details of the measurement optical system will be described later with reference to Fig. 3.

[0049] The fluid discharge unit 20 discharges fluid onto the cornea Ec of the subject's eye E. The fluid discharge unit 20 includes, for example, a cylinder 201, a piston 202, a solenoid actuator (hereinafter also referred to as a solenoid) 203, and an examination protrusion 9. The cylinder 201 and the piston 202 are used as an air compression mechanism that compresses air to be discharged into the subject's eye E. The cylinder 201 is, for example, cylindrical. The piston 202 slides along the axial direction of the cylinder 201. The piston 202 compresses air in an air compression chamber 234 inside the cylinder 201. The solenoid 203 includes a movable body 204 and a coil 205. The movable body 204 is made of, for example, a magnetic material such as a permanent magnet. When a current flows through the coil 205, a magnetic field is generated inside the coil 205. The movable body 204 is moved in the direction A in FIG. 2 by electromagnetic force received from the magnetic field. The movable body 204 is fixed to the piston 202 with screws, bolts, nuts, etc. (not shown). Therefore, the piston 202 moves together with the movable body 204. The movement of the movable body 204 moves the piston 202 in the compression direction (or forward direction, direction A in FIG. 1). The inspection protrusion 9 discharges the compressed air to the outside of the device.

[0050] The fluid compressed in the air compression chamber 234 inside the cylinder 201 by the movement of the piston 202 is ejected from the examination protrusion 9 toward the cornea Ec of the test eye E through a tube (which can also be a pipe) 220 connected to the tip of the cylinder 201 and an airtight chamber 221 that contains the compressed air.

[0051] Furthermore, the solenoid 203 of this embodiment can change the direction of movement of the movable body 204 by changing the direction of current flowing through the coil 205. For example, when a current flows in the forward direction through the coil 205, the movable body 204 moves in the compression direction (forward direction, direction A in FIG. 2), and when a current flows in the reverse direction, the movable body 204 moves in the opposite direction (rearward direction, direction B in FIG. 2). The ophthalmic apparatus 1 can move the piston 202 in direction A to compress the fluid in the air compression chamber 234, and then move the piston 202 in direction B to return it to its initial position.

[0052] The fluid discharge unit 20 includes a glass plate 208 and a glass plate 209. The glass plate 208 is transparent, holds the inspection protrusion 9, and transmits observation light and index light. The glass plate 209 forms the rear wall of the airtight chamber 221, and transmits observation light and index light.

[0053] The control unit 80 includes a CPU (processor) 81, a ROM 82, and a RAM 83. The CPU 81 controls various aspects of the ophthalmologic apparatus 1. The ROM 82 stores various programs, initial values, and the like. The RAM 83 temporarily stores various pieces of information. The ROM 82 and the RAM 83 are memories. The control unit 80 is connected to the display unit 7, the operation unit 8, and a storage unit 84. The storage unit (e.g., a non-volatile memory) 84 is a non-transitory storage medium that can retain its contents even when the power supply is cut off. For example, a hard disk drive, a flash ROM, a removable USB memory, or the like may be used as the storage unit 84. In this embodiment, control programs and the like for executing various processes described below are stored in the storage unit 84. Furthermore, the control unit 80 is electrically connected to the drive unit 4, the measurement optical system 10, the face photographing unit 12, and the like.

[0054] In this disclosure, the term "processor" refers to one or more hardware processors configured to execute computer program code (i.e., one or more instructions of a computer program) included in a computer program. In other words, a "processor" is a hardware device capable of executing one or more programmed processes. For example, a "processor" may be a general-purpose or special-purpose processor, such as a CPU, a microprocessor, a GPU, a DFP (Data Flow Processor), or the like.

[0055] In this disclosure, the term "memory" refers to one or more hardware memories that are non-transitory tangible recording media configured to store computer program code and / or data in a manner accessible to a processor. The "memory" may be implemented using memory technologies such as SRAM, SDRAM, non-volatile / flash-type memory, or other types of memory. Computer program code that constitutes a computer program is stored in the memory and executed by the processor to cause the ophthalmic device 1 to perform various functions.

[0056] In this disclosure, the term "circuit" refers to one or more hardware logic circuits configured to enable the ophthalmic device 1 to perform a function. In other words, "circuit" refers to one or more non-programmable devices. For example, a "circuit" may be a custom IC or the like that is non-programmably designed for a specific application.

[0057] In the present disclosure, at least one of a circuit and a processor having a memory storing computer program code causes the ophthalmic device 1 to realize a function. The expression "at least one of a circuit and a processor" should be interpreted as a disjunction (logical OR), and not as at least one circuit and at least one processor.

[0058] The optical system of the ophthalmic apparatus 1 will be described with reference to FIG. 3. The ophthalmic apparatus 1 includes an anterior-segment imaging unit (first image sensor) 35, such as a CCD camera. An image of the anterior segment of the subject's eye E, illuminated by an infrared light source for anterior-segment illumination (e.g., a non-collimated light source 92, etc., described later), is formed on the anterior-segment imaging unit 35 via a beam splitter 31, an objective lens 32, a dichroic mirror 33, an imaging lens 37, and a filter 34 (the above configuration may be referred to as an anterior-segment imaging optical system). The imaging optical axis L1 of the anterior-segment imaging unit 35 coincides with the examination axis IO (see FIG. 1). Therefore, the imaging optical axis L1 of the anterior-segment imaging unit 35 passes through the examination protrusion 9 (see FIGS. 1 and 2) and reaches the subject's eye E. The filter 34 transmits light from an infrared light source for anterior-segment illumination and an infrared light source 40 for alignment, but is opaque to light from a light source 50 for corneal deformation detection, described later, and visible light. The image (two-dimensional image) formed on the anterior eye imaging unit 35 is displayed on the display unit 7. In the following description, the two-dimensional image captured by the anterior eye imaging unit 35 is referred to as an anterior eye image 35a.

[0059] The light source 40 is part of a first target projection optical system 39 that projects a target onto a position on the subject's eye E through which the examination axis IO passes (i.e., on the examination axis IO). The first target projection optical system 39 emits target light along an optical axis L1 that coincides with the examination axis IO, thereby projecting a target, which is a bright spot, onto the cornea Ec of the subject's eye E (the apex of the cornea when alignment is complete). In other words, the first target projection optical system 39 projects a visual target onto the center EO of the measurement area of ​​the subject's eye E. The center EO of the measurement area of ​​the subject's eye E can be identified based on this bright spot. However, the method for identifying the center EO of the measurement area is not limited to this. For example, the center EO of the measurement area of ​​the subject's eye E may be identified based on four bright spots formed by a second target projection optical system, which will be described later. The first target projection optical system 39 includes a projection lens 41 and a beam splitter 31. Infrared light projected from the light source 40 via the projection lens 41 is reflected by the beam splitter 31 and projected from the front onto the subject's eye E. An index (corneal bright spot) formed on the cornea by the light source 40 is imaged on the anterior eye imaging unit 35 via the beam splitter 31 to the filter 34, and is used to detect alignment in the up, down, left, and right directions (the XY plane directions in FIG. 3) and to evaluate the focus state of the anterior eye image 35a.

[0060] The second target projection optical system projects an index for Z-direction adjustment onto the subject's eye E. In this embodiment, the second target projection optical system is used for Z-direction alignment with the subject's eye E and also for estimating the radius of curvature R of the cornea Ec of the subject's eye E. The second target projection optical system includes a collimated light source 90 and a non-collimated light source 92. The collimated light source 90 includes a pair of point light sources arranged symmetrically with respect to the imaging optical axis L1 of the anterior eye imaging unit 35. The second target projection optical system includes two collimating lenses 94, 94 corresponding to the pair of point light sources. The collimated light source 90 emits infrared light. Light (first irradiation light) emitted from each point light source of the collimated light source 90 is converted into parallel light when passing through the collimating lens 94. The parallel irradiation light (hereinafter referred to as collimated light) is reflected by the cornea Ec of the subject's eye E to project an infinity index. As a result, the collimated light emitted from the collimated light source 90 forms a pair of bright spots (hereinafter referred to as collimated bright spots 96, 96) on the anterior eye image 35a captured by the anterior eye imaging unit 35 (see FIG. 4).

[0061] The non-collimated light source 92 is a pair of point light sources arranged symmetrically with respect to the imaging optical axis L1 of the anterior-segment imaging unit 35. Each point light source of the non-collimated light source 92 irradiates the cornea Ec of the subject's eye E with diffused light (first irradiation light). The light reflected by the cornea Ec of the subject's eye E (hereinafter referred to as non-collimated light) projects a finite target. As a result, the non-collimated light emitted from the optical collimated light source 92 forms a pair of bright spots (hereinafter referred to as non-collimated bright spots 98, 98) on the anterior-segment image 35a captured by the anterior-segment imaging unit 35 (see FIG. 4). As will be described later, alignment (first alignment) of the ophthalmologic apparatus 1 in at least the Z direction is performed based on the four bright spots (a pair of collimated bright spots 96, 96 and a pair of non-collimated bright spots 98, 98) formed on the anterior-segment image 35a.

[0062] However, the second target projection optical system is not limited to the above configuration. For example, the collimated light source 90 and the non-collimated light source 92 of the second target projection optical system may each be configured as a single point light source. In this case, one collimated bright spot 96 and one non-collimated bright spot 98 are formed on the anterior eye image 35a captured by the anterior eye imaging unit 35. Furthermore, for example, the non-collimated light source 92 of the second target projection optical system may be configured as a ring light source arranged in a ring shape centered on the imaging optical axis L1. In such a second target projection optical system, the non-collimated light source 92 projects a ring target (so-called Mayer ring) onto the cornea Ec of the subject's eye E. As a result, a pair of collimated bright spots 96, 96 and one non-collimated ring bright spot are formed on the anterior eye image 35a captured by the anterior eye imaging unit 35. Furthermore, the collimated light source 90 of the second target projection optical system may also be configured as a ring light source arranged in a ring shape centered on the imaging optical axis L1. In this case, the light emitted from the collimated light source 90 is converted into ring-shaped parallel light as it passes through the collimating lens and reaches the cornea Ec of the subject's eye E. As a result, the collimated light source 90 projects a ring target onto the cornea Ec of the subject's eye E. In this case, one collimated ring bright spot and one non-collimated ring bright spot are formed coaxially around the imaging optical axis L1 (the center EO of the measurement area of ​​the subject's eye E) on the anterior eye image 35a captured by the anterior eye imaging unit 35.

[0063] The fixation optical system 48 has an optical axis L1 and presents a fixation target to the subject's eye E from a front direction. The fixation optical system 48 has a visible light source (fixation lamp) 45, a projection lens 46, and a dichroic mirror 33, and projects light onto the subject's eye E to make the subject's eye fixate in a front direction. A light source such as an LED or laser is used as the visible light source 45. The visible light emitted from the visible light source 45 passes through the projection lens 46, is reflected by the dichroic mirror 33, passes through the objective lens 32, and is then projected onto the fundus of the subject's eye E. As a result, the subject's eye E is brought into a state of fixating the fixation target in a front direction, and its line of sight is fixed.

[0064] The corneal deformation detection optical system includes a light projecting optical system 500a and a light receiving optical system 500b, and is used to detect the deformation state of the cornea Ec. Each of the optical systems 500a and 500b is disposed in the measurement optical system 10 in the examination unit, and is moved three-dimensionally by the drive unit 4.

[0065] The light projecting optical system 500a has an optical axis L3 as a light projecting optical axis, and projects irradiation light obliquely toward the cornea Ec of the subject's eye E. The light projecting optical system 500a includes, for example, an infrared light source 50, a collimator lens 51, and a beam splitter 52. The light receiving optical system 500b includes a photodetector 57 and receives reflected light of the irradiation light from the cornea Ec of the subject's eye E. The light receiving optical system 500b is disposed approximately symmetrically to the light projecting optical system 500a with respect to the optical axis L1. The light receiving optical system 500b includes, for example, a lens 53, a beam splitter 55, a pinhole plate 56, and a photodetector 57, and forms an optical axis L2 as a light receiving optical axis.

[0066] The light emitted from the light source 50 is converted into a substantially parallel beam by the collimator lens 51, reflected by the beam splitter 52, and then becomes coaxial with (coincides with) the optical axis L3 of the light-receiving optical system 70b (described later), and is projected onto the cornea Ec of the subject's eye E. The light reflected by the cornea Ec becomes coaxial with (coincides with) the optical axis L2 of the light-projecting optical system 70a (described later), passes through the lens 53, is reflected by the beam splitter 55, passes through a pinhole plate 56, and is received by the photodetector 57. The lens 53 is coated with a coating that is opaque to the light from the light source 30 and the light source 40. The optical system for detecting corneal deformation is positioned so that the amount of light received by the photodetector 57 is maximized when the subject's eye is in a predetermined deformation state (flat state).

[0067] The corneal thickness measurement optical system (second optical system) includes a light-projecting optical system 70a, a light-receiving optical system 70b, and a fixation optical system 48, and is used to measure the corneal thickness of the subject's eye E. In this embodiment, part of the light-projecting optical system 70a and part of the corneal deformation detection optical system are used together. The light-projecting optical system 70a irradiates the cornea Ec of the subject's eye E with irradiation light (second irradiation light) as measurement light from an oblique direction. The light-projecting optical system 70a includes an irradiation light source (second light source) 71, a condenser lens 72, a light-limiting member 73, a concave lens 74, and a lens 53 that also serves as the corneal deformation detection optical system. The irradiation light source 71 is a visible light source or an infrared light source (including near-infrared), such as an LED or laser. The condenser lens 72 condenses the light emitted from the light source 71. As a result, the light emitted from the light source 71 is condensed on the cornea of ​​the subject's eye E.

[0068] The light limiting member 73 is disposed in the optical path of the light projecting optical system 70a and limits the light emitted from the light source 71. The light limiting member 73 is disposed at a position approximately conjugate with the cornea Ec. For example, a pinhole plate, a slit plate, or the like is used as the light limiting member 73. The light limiting member 73 is used as an aperture that passes a portion of the light emitted from the light source 71 and blocks the other light. The light projecting optical system 70a then forms a predetermined pattern light beam (for example, a spot light beam or a slit light beam) on the cornea of ​​the eye E.

[0069] The light receiving optical system 70b has a light receiving element (second image capturing element) 77, and receives reflected light of the irradiated light from the surface (outer skin) and back surface (endothelium) of the cornea of ​​the eye E. The light receiving optical system 70b is disposed approximately symmetrically with the light projecting optical system 70a with respect to the optical axis L1. The light receiving optical system 70b has a light receiving lens 75, a concave lens 76, and a light receiving element 77, and forms an optical axis L3 as a light receiving optical axis.

[0070] Light emitted from the irradiation light source 71 is condensed by the condenser lens 72 and illuminates the light-limiting member 73 from behind. After being limited by the light-limiting member 73, the light from the light source 71 is focused (condensed) near the cornea Ec by the lens 53. For example, a pinhole image (when a pinhole plate is used) or a slit image (when a slit plate is used) is formed near the cornea Ec. At this time, the light from the light source 71 is focused near the intersection with the visual axis on the cornea Ec. The reflected light of the irradiation light from the cornea Ec travels in a direction symmetrical to the projected light beam with respect to the optical axis L1. The reflected light is then focused by the light-receiving lens 75 on the light-receiving surface of the light-receiving element 77.

[0071] Next, the characteristics of the anterior eye image 35a captured by the anterior eye imaging unit 35 of the ophthalmologic apparatus 1 of this embodiment will be described with reference to FIGS.

[0072] 4 and 5 show an anterior-segment image 35a captured by the anterior-segment imaging unit 35 in a state where the examination axis IO coincides with the corneal apex of the subject's eye E (i.e., a state where alignment of the ophthalmologic apparatus 1 in the XY plane direction with respect to the subject's eye E is complete). Furthermore, in FIG. 5, not only alignment in the XY plane direction but also alignment in the Z direction (i.e., the direction along the examination axis IO) is complete. As shown in FIGS. 4 and 5, a pair of collimated bright spots 96, 96 and a pair of non-collimated bright spots 98, 98 are formed in the anterior-segment image 35a captured by the anterior-segment imaging unit 35.

[0073] The positions of the pair of collimated bright spots 96, 96 remain almost constant between when alignment in the Z direction is complete ( FIG. 4 ) and when alignment in the Z direction is not complete ( FIG. 5 ). That is, while the ophthalmic apparatus 1 (more precisely, the housing 3) is moved relative to the subject's eye E in the Z direction, the distance L1 between the pair of collimated bright spots 96, 96 formed on the anterior-segment image 35 a remains almost constant. On the other hand, the positions of the pair of non-collimated bright spots 98, 98 change between when alignment in the Z direction is complete ( FIG. 4 ) and when alignment in the Z direction is not complete ( FIG. 5 ). That is, while the ophthalmic apparatus 1 is moved relative to the subject's eye E in the Z direction, the distance L2 between the pair of non-collimated bright spots 98, 98 formed on the anterior-segment image 35 a changes. In this embodiment, rough alignment in the Z direction is performed by utilizing the characteristic that when the ophthalmic device 1 is moved relatively in the Z direction, the position of the non-collimated bright spot 98 changes relative to the position of the collimated bright spots 96, 96.

[0074] More specifically, the position of the ophthalmic apparatus 1 in the Z direction is roughly estimated from the ratio of the distance L2 between the non-collimated bright spots 98 to the distance L1 between the collimated bright spots 96 (hereinafter referred to as the bright spot ratio). FIG. 6 shows the relationship between the working distance ΔWD in the Z direction of the ophthalmic apparatus 1 and the bright spot ratio for each different corneal curvature radius R. The working distance ΔWD refers to the relative distance (amount of deviation) to the position where the Z direction alignment of the ophthalmic apparatus 1 (housing 3) is completed (hereinafter referred to as the measurement position). As shown in FIG. 6, for each curvature radius R, the bright spot ratio changes approximately linearly with the working distance ΔWD. Therefore, the bright spot ratio when the ophthalmic apparatus 1 is aligned (i.e., when the ophthalmic apparatus 1 reaches the measurement position (ΔWD=0)) is calculated in advance. Then, by moving the ophthalmologic apparatus 1 in the Z direction so as to achieve this value of the ratio between bright spots, rough alignment in the Z direction can be performed. In the following description, alignment in the Z direction based on the ratio between bright spots will be referred to as first alignment.

[0075] However, the relationship between the working distance ΔWD of the ophthalmic apparatus 1 and the inter-bright spot ratio varies depending on the radius of curvature of the cornea. Therefore, in this embodiment, the radius of curvature R of a specific cornea is set as the reference radius, and the inter-bright spot ratio when the ophthalmic apparatus 1 reaches the measurement position in the Z direction for a cornea having this reference radius R is measured in advance as the reference ratio. Note that, for example, the average radius of curvature of the cornea may be used as the reference radius. In this embodiment, 7.8 mm is used as the reference radius. FIG. 7 shows measurements of the working distance ΔWD (deviation amount) from the measurement position when the reference ratio is achieved for corneas having various radii of curvature R. As shown in FIG. 7, for a cornea with the reference radius of curvature (7.8 mm), the position of the ophthalmic apparatus 1 in the Z direction when the reference ratio is achieved is the measurement position (deviation amount = 0). However, as the radius of curvature of the cornea deviates from the reference radius, the deviation amount changes approximately linearly.

[0076] FIG. 8 shows the positions of bright spots (epithelial reflection bright spots 100a) formed on the two-dimensional image (hereinafter referred to as measurement image 77a) captured by the light-receiving element 77 when the inter-bright spot ratio reaches the reference ratio for corneas having each radius of curvature R plotted in FIG. 7. As shown in FIG. 8, for a cornea with a radius of curvature R of the reference radius (7.8 mm), the bright spot 100a is located approximately at the center of the measurement image (hereinafter referred to as the target position). When the radius of curvature R is within the range of 7 mm≦R≦9 mm, the bright spot 100a is relatively clearly formed on the measurement image 77a when the inter-bright spot ratio reaches the reference ratio. On the other hand, when the radius of curvature R is 6 mm, approximately half of the bright spot 100a on the measurement image 77a is missing (incompletely formed) when the inter-bright spot ratio reaches the reference ratio. Furthermore, when the radius of curvature R is 5 mm or less, the bright spot 100a is not formed on the measurement image 77a. In addition, for corneas whose radius of curvature R is smaller than the reference radius, when the ratio between bright spots reaches the reference ratio, the Z-direction position of the ophthalmic device 1 is farther from the test eye E than the measurement position for each cornea (shift amount ΔWD>0).

[0077] On the other hand, when the radius of curvature R is 10 mm and 11 mm, the bright spot 100a on the measurement image 77a is incompletely formed when the ratio between bright spots reaches the reference ratio. Furthermore, when the radius of curvature R is 12 mm or greater, the bright spot 100a is not formed on the two-dimensional image when the ratio between bright spots reaches the reference ratio. For corneas with a radius of curvature R greater than the reference radius, when the ratio between bright spots reaches the reference ratio, the position of the ophthalmologic apparatus 1 in the Z direction is closer to the subject's eye E than the measurement position for each cornea (shift amount ΔWD<0).

[0078] Therefore, in the ophthalmic apparatus 1 of this embodiment, the control mode of the first alignment is changed according to the corneal radius of curvature R. Specifically, when the corneal radius of curvature R is within a predetermined range centered on a reference radius (for example, when the radius of curvature R is 7.0 mm≦R≦9.0 mm), the ophthalmic apparatus 1 is moved in the Z direction toward the subject's eye E so that the inter-bright spot ratio becomes the reference ratio. When the inter-bright spot ratio becomes the reference ratio, the bright spot 100a is clearly formed on the two-dimensional image captured by the light receiving element 77, and the first alignment is terminated. On the other hand, when the corneal radius of curvature R is smaller than the predetermined range (for example, when the radius of curvature R is R<7.0 mm), the ophthalmic apparatus 1 is moved in the Z direction toward the measurement position. Because the ophthalmic apparatus 1 has not yet reached the measurement position when the inter-bright spot ratio becomes the reference ratio, the ophthalmic apparatus 1 continues to move in the Z direction even after the inter-bright spot ratio becomes the reference ratio. The first alignment is then terminated when bright spot 100a appears on measurement image 77a captured by light-receiving element 77. In this way, when radius of curvature R is within a predetermined range or less than the predetermined range, the ratio between bright spots is used as a factor for determining the timing to terminate the first alignment. Therefore, the ratio between bright spots functions as a reference value for determining the timing to transition from the first alignment to the second alignment.

[0079] Furthermore, if the corneal curvature radius R is larger than a predetermined range (if the curvature radius R is R>10 mm), the ophthalmic apparatus 1 is moved in the Z direction toward the measurement position. In this case, if the ratio between bright spots reaches the reference ratio, the ophthalmic apparatus 1 will pass the measurement position, posing a risk of contact with the subject. Therefore, the first alignment is terminated before the ratio between bright spots reaches the reference ratio, at the timing when a bright spot 100a is formed on the measurement image 77a captured by the light receiving element 77.

[0080] (Estimation of radius of curvature R) As described above, the ophthalmic apparatus 1 changes the control mode of the first alignment depending on the radius of curvature R of the cornea of ​​the subject's eye E. Therefore, when performing the first alignment, it is necessary to measure the radius of curvature R of the cornea Ec of the subject's eye E. Therefore, in the ophthalmic apparatus 1 of this embodiment, the radius of curvature R of the cornea Ec is estimated based on the bright spots formed by the second target projection optical system. Specifically, in this embodiment, the radius of curvature R of the cornea Ec is estimated based on the distance L1 between the pair of collimated bright spots 96, 96. FIG. 9 is a graph showing the relationship between the distance L1 between the pair of collimated bright spots 96, 96 and the radius of curvature R of the cornea Ec when the ophthalmic apparatus 1 is at different working distances (when the shift amount ΔWD=0 and when the shift amount ΔWD=+2.0 mm). As shown in FIG. 9 , regardless of the working distance of the ophthalmic apparatus 1, the distance L1 between the collimated bright spots 96, 96 depends approximately linearly on the radius of curvature R of the cornea Ec. That is, if the radius of curvature R is the same, the distance L1 between the collimated bright spots 96, 96 will be approximately constant regardless of the working distance ΔWD of the ophthalmic apparatus 1. Therefore, the radius of curvature R can be estimated by determining the distance L1 between the collimated bright spots 96, 96. Specifically, for example, the distance L1 between each collimated bright spot 96, 96 and the corresponding radius of curvature R may be stored in advance as a map, and the corresponding radius of curvature R may be determined from the distance L1 between the collimated bright spots 96, 96. Alternatively, a function of the radius of curvature R that depends on the distance L1 between the collimated bright spots 96, 96 may be stored, and the radius of curvature R may be calculated from the distance L1 between the collimated bright spots 96, 96.

[0081] However, the method for estimating the radius of curvature R of the cornea is not limited to the above. For example, it is also possible to estimate the radius of curvature R from the distance L2 between a pair of non-collimated bright spots 98. In this case, however, the accuracy of the radius of curvature R estimated from the distance L2 between the non-collimated bright spots 98 will be lower than the accuracy of the radius of curvature R estimated from the distance L1 between the collimated bright spots 96. Furthermore, the ophthalmic apparatus 1 may acquire information on the radius of curvature R of the cornea of ​​the subject's eye measured by a keratometry device, and change the control mode of the first alignment according to the acquired radius of curvature R.

[0082] (Regarding abnormality detection during the second alignment) In the ophthalmologic apparatus 1 according to this embodiment, once the first alignment is completed, the second alignment is performed. The second alignment is performed based on light emitted from the irradiation light source 71 to measure the corneal thickness in the corneal thickness measurement optical system. As described above, the light emitted from the irradiation light source 71 is focused on the cornea Ec of the subject's eye E. The light reflected by the cornea Ec of the subject's eye E is received by the light receiving element 77, and a bright spot (hereinafter referred to as a corneal reflection bright spot 100) is formed on the measurement image 77a captured by the light receiving element 77. More specifically, the corneal reflection bright spot 100 is formed on the measurement image 77a by an epithelial reflection bright spot 100a formed by light reflected by the epithelium of the cornea and an endothelial reflection bright spot 100b formed by light reflected by the endothelium of the cornea.

[0083] FIG. 10 schematically illustrates a state in which the center EO of the measurement area of ​​the subject's eye E coincides with the examination axis IO (i.e., the alignment of the examination optical axis L1 with respect to the subject's eye E in the XY plane is consistent). As shown in FIG. 10, when the alignment in the XY plane is correctly set, an epithelial reflection bright spot 100a and an endothelial reflection bright spot 100b are clearly formed on the measurement image 77a captured by the light-receiving element 77. At this time, the pair of collimated bright spots 96, 96 and the pair of non-collimated bright spots 98, 98 are also positioned based on the center EO of the measurement area of ​​the subject's eye E. On the other hand, as shown in FIG. 11, there may be a state in which the alignment in the XY plane is deviated by more than a predetermined amount (in FIG. 11, the pair of collimated bright spots 96, 96 and the pair of non-collimated bright spots 98, 98 are displaced upward from the center EO of the measurement area of ​​the subject's eye E). In this state, light emitted from the irradiation light source 71 of the corneal thickness measurement optical system may not be reflected by the cornea Ec, but may be reflected by a part of the subject other than the cornea (for example, the eyelid 102). In this case, a bright spot 100c other than the epithelial reflection bright spot 100a and the endothelial reflection bright spot 100b (in the example of FIG. 11, a bright spot 100c due to light reflected by the eyelid 102 of the subject) is formed on the measurement image 77a captured by the light receiving element 77.

[0084] Furthermore, even if the alignment in the XY plane direction is set correctly, there may be cases where the subject closes his or her eyes. In this case, the pair of collimated bright spots 96, 96 and the pair of non-collimated bright spots 98, 98 will not be formed on the anterior eye segment image 35a captured by the anterior eye segment imaging unit 35. Even in this case, a bright spot 100c other than the epithelial reflection bright spot 100a and the endothelial reflection bright spot 100b (i.e., a bright spot 100c due to light reflected by the eyelid 102) will be formed on the measurement image 77a captured by the light receiving element 77.

[0085] Therefore, in the ophthalmic device 1 of this embodiment, during the second alignment, the second alignment is configured to be stopped if (1) the center EO of the measurement area of ​​the test eye E is more than a predetermined distance away from the examination axis IO and a bright spot 100c caused by light reflected by somewhere other than the cornea of ​​the test eye E is formed on the measurement image 77a captured by the light receiving element 77, or (2) neither a collimated bright spot 96 nor a non-collimated bright spot 98 is formed on the anterior eye image 35a captured by the anterior eye photographing unit 35 and a bright spot 100c caused by light reflected by somewhere other than the cornea of ​​the test eye E is formed on the measurement image 77a captured by the light receiving element 77.

[0086] (Regarding processing by the ophthalmic device 1) Next, an example of processing executed by the ophthalmologic apparatus 1 of this embodiment will be described with reference to FIGS. 12 to 17. As shown in FIG. 12, the ophthalmologic apparatus 1 executes an XY plane alignment process S100, a first alignment process S200, a second alignment process S300, and a measurement process S400. These processes are performed by the CPU 81 of the control unit 80 executing a computer program stored in the storage unit 84. In the XY plane alignment process S100, alignment in the XY plane direction with respect to the subject's eye E is performed. More specifically, the CPU 81 controls the operation of the actuator 4a of the drive unit 4 so that the bright point of the index light irradiated from the first index projection optical system 39 coincides with the center EO of the measurement area of ​​the subject's eye E. When alignment in the XY plane direction is completed, the CPU 81 ends the XY plane alignment process S100 and proceeds to the first alignment process S200.

[0087] (Regarding the first alignment process S200) Next, the first alignment process S200 executed by the CPU 81 will be described with reference to the flowcharts of FIGS. 13 to 16. It is assumed that, upon completion of the XY plane alignment process S100, the housing 3 of the ophthalmic apparatus 1 is in an initial position sufficiently distant from the subject's eye E and the measurement position. Then, in the first alignment process S200, the housing 3 of the ophthalmic apparatus 1 is moved in the Z direction from the initial position toward the subject's eye E by the drive unit 4. In the first alignment process S200, rough alignment in the Z direction with respect to the ophthalmic apparatus is performed based on the light irradiated by the second target projection optical system. In the first alignment process S200, first, the radius of curvature R of the cornea of ​​the subject's eye E is estimated. The CPU 81 identifies a pair of collimated bright points 96, 96 formed in the anterior eye image 35a captured by the anterior eye imaging unit 35 (S201). Next, the CPU 81 measures the distance L1 between the two identified collimated bright spots 96 (S202). When measuring the distance L1 between the two collimated bright spots 96, 96, the approximate distance between the housing 3 of the ophthalmic apparatus 1 and the subject's eye E may be taken into consideration. The approximate distance between the housing 3 and the subject's eye E may be calculated based on the positional relationship between the two collimated bright spots 96 and the two non-collimated bright spots 98. Then, the CPU 81 refers to the memory unit 84 and estimates the radius of curvature R of the cornea of ​​the subject's eye E from the measured distance L1 between the collimated bright spots 96 (S203).

[0088] Next, the CPU 84 determines whether the estimated curvature radius R is within a predetermined range (S204). If the curvature radius R is within the predetermined range (S204: YES), the CPU 84 determines to execute a first rough alignment process S205 (S205). On the other hand, if the curvature radius R is outside the predetermined range (S204: NO), the CPU 84 determines whether the curvature radius R is less than the predetermined range (S206). If the curvature radius R is less than the predetermined range (S206: YES), the CPU 84 determines to execute a second rough alignment process S207 (S207). Furthermore, if the curvature radius R is greater than the predetermined range (S206: NO), the CPU 84 determines to execute a third rough alignment (S208).

[0089] (First rough alignment process S205) 14, in the first rough alignment process S205, the CPU 81 controls the drive unit 4 to start moving the ophthalmic apparatus 1 from the initial position along the Z direction toward the subject (S209). Next, the CPU 81 identifies a pair of collimated bright spots 96, 96 and a pair of non-collimated bright spots 98, 98 formed in the anterior eye image 35a (S210). The CPU 81 measures the distance L1 between the pair of collimated bright spots 96, 96 and the distance L2 between the pair of non-collimated bright spots 98, 98 (S211). Then, the CPU 81 calculates the ratio (inter-bright spot ratio) of the measured distance L2 between the non-collimated bright spots 98, 98 to the distance L1 between the collimated bright spots 96, 96 (S212).

[0090] After calculating the inter-bright spot ratio, the CPU 81 refers to the storage unit 84 and determines whether the calculated inter-bright spot ratio value matches the reference ratio stored in the storage unit 84 (S213). If it does not match the reference value (S213: NO), the CPU 81 returns to step S212 and calculates the inter-bright spot ratio again. That is, while the ophthalmic apparatus 1 moves in the Z direction, the distance L1 between the pair of collimated bright spots 96, 96 is kept approximately constant, while the distance L2 between the pair of non-collimated bright spots 98, 98 changes. Therefore, the CPU 81 continues to calculate the inter-bright spot ratio while the ophthalmic apparatus 1 moves in the Z direction. Then, when the inter-bright spot ratio matches the reference ratio (S213: YES), the CPU 81 ends the first rough alignment process S205 and proceeds to the second alignment process S300.

[0091] In this way, if the radius of curvature R is within a predetermined range, the first rough alignment process S205 is executed. In the first rough alignment process S205, the ophthalmic apparatus 1 is moved closer to the subject's eye E until the ratio between bright spots reaches the standard ratio. Then, when the ratio between bright spots matches the standard ratio, a corneal reflection bright spot 100 appears on the measurement image 77a (see Figures 8(c) to (g)). As a result, the second alignment can be executed based on the corneal reflection bright spot 100 that appears on the measurement screen. In other words, if the radius of curvature R is within a predetermined range, the ophthalmic apparatus 1 can be moved so that the ratio between bright spots matches the standard ratio, which simplifies the process.

[0092] (Second rough alignment process S207) Next, the second rough alignment process S207 will be described with reference to FIG. 15. In the second rough alignment process S207, only the differences from the first rough alignment process S205 will be described, and the same steps as those in the first rough alignment process S205 will be assigned the same reference numerals and will not be described in detail. When the CPU 81 causes the drive unit 4 to start moving the ophthalmic apparatus 1 in the Z direction (S209), it identifies the collimated bright spots 96 and the non-collimated bright spots 98 (S210). Next, it measures the distance L1 between the collimated bright spots 96, 96 and the distance L2 between the non-collimated bright spots 98, 98 (S211) and calculates the inter-bright spot ratio (S212). Then, it moves the ophthalmic apparatus 1 until the inter-bright spot ratio matches the reference ratio (S213). In the second rough alignment process S207, if the ratio between bright spots matches the reference ratio (S213: YES), the CPU 81 controls the drive unit 4 to move the ophthalmic apparatus 1 further toward the subject's eye E (S214). Thus, if the corneal curvature radius R is below the predetermined range, the ophthalmic apparatus 1 does not reach the measurement position even if the ratio between bright spots matches the reference value. At this time, as shown in FIGS. 8(a) and 8(b), the corneal reflection bright spot 100 does not appear clearly or does not appear at all in the measurement image 77a. Therefore, in the second rough alignment process S207, the movement of the ophthalmic apparatus 1 continues even if the ratio between bright spots reaches the reference value.

[0093] Next, the CPU 81 determines whether the corneal reflection bright spot 100 appears in the measurement image 77a captured by the light receiving element 77 (S215). If the corneal reflection bright spot 100 cannot be detected (S215: NO), the CPU 81 causes the drive unit 4 to move the ophthalmic apparatus 1 further toward the subject's eye E, and returns the process to step S214. In this way, if the corneal reflection bright spot 100 is not detected and the ophthalmic apparatus 1 is far from the measurement position, the CPU 81 continues to move the ophthalmic apparatus 1 until the corneal reflection bright spot 100 is detected. Then, if the corneal reflection bright spot 100 is detected on the measurement image 77a (S215: YES), the CPU 81 ends the second rough alignment process S207 and proceeds to the second alignment process S300.

[0094] In this way, when the radius of curvature R is less than the predetermined range, even if the ophthalmic apparatus 1 is brought closer to the subject's eye E until the ratio between bright spots matches the reference ratio, the corneal reflection bright spot 100 will not be detected (the ophthalmic apparatus 1 is far from the measurement position). Therefore, in the second rough alignment process S207, even after the ratio between bright spots reaches the reference ratio, the ophthalmic apparatus 1 is brought even closer to the subject's eye E, and alignment continues until the corneal reflection bright spot 100 is detected.

[0095] (Third rough alignment process S208) Next, the third rough alignment process S208 will be described below with reference to FIG. 16. In the third rough alignment process S208, only differences from the first rough alignment process S205 will be described. Steps identical to those in the first rough alignment process S205 are denoted by the same reference numerals and will not be described in detail. When the CPU 81 causes the drive unit 4 to start moving the ophthalmic apparatus 1 in the Z direction (S209), it identifies the collimated bright spots 96 and the non-collimated bright spots 98 (S210). Next, the CPU 81 measures the distance L1 between the collimated bright spots 96 and the distance L2 between the non-collimated bright spots 98 (S211) and calculates the inter-bright spot ratio (S212). Then, the CPU 81 causes the drive unit 4 to move the ophthalmic apparatus 1 in a direction closer to the subject's eye E so that the inter-bright spot ratio approaches the reference ratio.

[0096] Here, if the curvature radius R of the cornea E is larger than the predetermined range (see FIGS. 8(h) to 8(k)), the corneal reflection bright spot 100 will appear unclearly or not at all in the measurement image 77a. Moreover, when the inter-bright spot ratio reaches the reference value, the ophthalmic apparatus 1 will have passed the measurement position and approached the subject's eye. Therefore, in the third rough alignment process S208, the CPU 81 determines whether the corneal reflection bright spot 100 appears in the measurement image 77a captured by the light receiving element 77 before the inter-bright spot ratio reaches the reference value (S216). If the corneal reflection bright spot 100 is not detected in the measurement image 77a (S216: NO), the CPU 81 returns to step S212 and repeats the calculation of the inter-bright spot ratio. Then, when the corneal reflection bright spot 100 is detected on the measurement image 77a (S216: YES), the CPU 81 ends the third rough alignment process S208 and proceeds to the second alignment process S300.

[0097] Thus, when the corneal curvature radius R is larger than the predetermined range, a corneal reflection bright spot 100 appears on the measurement image 77a captured by the light-receiving element 77 before the inter-bright spot ratio reaches the reference ratio. Therefore, in the third rough alignment process S208, the CPU 81 determines whether or not a corneal reflection bright spot 100 is detected on the measurement image 77a while the ophthalmic apparatus 1 is brought closer to the subject's eye E. If the corneal reflection bright spot 100 is detected on the measurement screen 77a, the third rough alignment process S208 is terminated before the inter-bright spot ratio reaches the reference value. Therefore, the third rough alignment process S208 can prevent the ophthalmic apparatus 1 from coming into contact with the subject. Although the inter-bright spot ratio is calculated in the third rough alignment process, it is not necessarily required to calculate the inter-bright spot ratio. That is, when the corneal curvature radius R is larger than a predetermined range, it is possible to omit the calculation of the ratio between bright spots by monitoring whether or not the corneal reflection bright spot 100 appears in the measurement image 77a.

[0098] (Regarding the second alignment process S300) Next, the second alignment process S300 executed by the ophthalmic apparatus 1 will be described below with reference to Fig. 17. The second alignment process S300 is started when the Z-direction position of the ophthalmic apparatus 1 approaches the measurement position in the first alignment process S20. In other words, the second alignment is started when the corneal reflection bright spot 100 appears on the measurement image 77a captured by the light receiving element 77.

[0099] When the second alignment process S300 starts, the CPU 81 causes the drive unit 4 to start moving the ophthalmologic apparatus 1 in the Z direction (S301). Next, the CPU 81 determines whether the measurement area center EO of the subject's eye E is separated from the examination axis IO by a predetermined distance or more (S302). If the measurement area center EO is not separated from the examination axis IO by a predetermined distance or more (S302: NO), the CPU 81 proceeds to step S304. On the other hand, if the measurement area center EO is separated from the examination axis IO by a predetermined distance or more (S302: YES), the CPU 81 proceeds to step S303. In step S303, the CPU 81 determines whether a bright spot 100c other than the corneal reflection bright spot 100 is formed on the measurement image 77a. For example, it is assumed that the subject's eye E is displaced in the XY plane, causing the light of the corneal thickness measurement optical system to be reflected by the subject's eyelid 102, etc. In this case, a bright spot other than the corneal reflection bright spot 100 is detected on the measurement image 77a. When such a bright spot 100c other than the corneal reflection bright spot 100 is detected (S303: YES), the CPU 81 stops movement of the ophthalmic apparatus 1 in the Z direction and terminates the second alignment process S300. On the other hand, when a bright spot 100c other than the corneal reflection bright spot 100 is not detected (S303: NO), the CPU 81 transitions the process to step S304. That is, the CPU 81 monitors whether or not a positional deviation of the measurement area center EO has occurred while continuing the alignment of the ophthalmic apparatus 1 in the Z direction.

[0100] In this way, if a positional deviation of the measurement area center EO occurs and a bright spot 100c other than the corneal reflection bright spot 100 is detected, the second alignment process S300 is stopped. Therefore, it is possible to prevent the alignment of the ophthalmic device 1 from being performed based on an inaccurate bright spot 100c other than the corneal reflection bright spot 100. As a result, it is possible to avoid a situation in which the ophthalmic device 1 gets too close to the subject and makes contact. Note that when the CPU 81 determines whether a bright spot 100c other than the corneal reflection bright spot 100 has been detected, it can make this determination, for example, from the positional relationship of the corneal reflection bright spot 100. Specifically, as shown in FIG. 10, when the light of the corneal thickness measurement optical system is correctly reflected by the cornea, the endothelial reflection bright spot 100a and the epithelial reflection bright spot 100b are always detected as the corneal reflection bright spot 100 in the same positional relationship. Therefore, if the endothelial reflection bright spot 100a and the epithelial reflection bright spot 100b are not detected in the correct positional relationship, the CPU 81 can determine that a bright spot 100c other than the corneal reflection bright spot 100 has been formed. However, instead of this method, it may be determined that the bright spot 100c is other than the corneal reflection bright spot 100 from the size and brightness of the bright spot formed in the measurement image 77a. Furthermore, in addition to these methods, the determination may be made taking into account the position in the XY plane of the anterior eye image 35a captured by the anterior eye imaging unit 35.

[0101] In step S304, the CPU 81 determines whether or not a bright spot due to light from the second target projection optical system (i.e., a collimated bright spot 96 and a non-collimated bright spot 98) is formed in the anterior-segment image 35a captured by the anterior-segment imaging unit 35. That is, even if no positional deviation of the measurement area center EO occurs in step S302, for example, the light from the second target projection optical system may be reflected by something other than the cornea (e.g., the eyelid 102) when the subject blinks. In this case, the collimated bright spot 96 and the non-collimated bright spot 98 are not formed in the anterior-segment image 35a captured by the anterior-segment imaging unit 35. Therefore, if a bright spot due to light from the second target projection optical system is not detected in step S304 (S304: YES), the CPU 81 transitions the process to step S305. Then, in step S305, if a bright spot 100c other than a corneal bright spot is detected (S305: YES), the CPU 81 stops the movement of the ophthalmologic apparatus 1 in the Z direction and stops the second alignment process S300.

[0102] In this way, even if there is no positional deviation of the measurement area center EO, ​​if the subject blinks and a bright spot 100c other than the corneal reflection bright spot 100 is detected in the measurement image 77a, the second alignment process S300 is stopped. This prevents the alignment of the ophthalmic device 1 from continuing based on an inaccurate bright spot 100c other than the corneal reflection bright spot 100. As a result, it is possible to avoid a situation in which the ophthalmic device 1 comes close to the subject and comes into contact with the subject.

[0103] On the other hand, if a bright spot due to light from the second target projection optical system is detected in step S304 (S304: NO), the CPU 81 determines whether the corneal reflection bright spot 100 on the measurement image 77a has reached the target position (S306). The target position is, for example, the center position in the horizontal direction of the measurement image 77a, as shown in FIG. 10. This target position is preset so that the ophthalmologic apparatus 1 reaches the measurement position when the corneal reflection bright spot 100 (endothelial reflection bright spot 100b in FIG. 10) reaches the target position. If the corneal reflection bright spot 100 on the measurement image 77a has not reached the target position (S306: NO), the CPU 81 returns to step S302 and repeats steps S302 to S305 until the corneal reflection bright spot 100 reaches the target position. On the other hand, when the corneal reflection bright spot 100 reaches the target position (S306: YES), the CPU 81 stops the movement of the ophthalmic device 1 in the Z direction, terminates the second alignment process S300, and proceeds to the measurement process S400 (see Figure 12).

[0104] As described above, in the second alignment process S300, the ophthalmic apparatus 1 is aligned in the Z direction based on the light from the corneal thickness measurement optical system focused on the cornea Ec. Therefore, precise alignment can be performed after the ophthalmic apparatus 1 has approached the subject's eye E to a certain extent through the first alignment. Furthermore, if the CPU 81 detects a bright spot 100c reflected from somewhere other than the cornea while it is unable to detect a positional shift of the measurement area center EO or a bright spot reflected by the light from the second target projection optical system, it halts the second alignment process S300. Therefore, it is possible to avoid performing the second alignment based on an inaccurate bright spot 100c other than the corneal reflection bright spot 100. As a result, the safety of the subject can be ensured.

[0105] Upon completion of the second alignment process S300, the CPU 81 automatically starts the measurement process S400. In the measurement process S400, the CPU 81 first measures the corneal thickness of the subject's eye E based on the corneal reflection bright spot 100 appearing in the measurement image 77a. Specifically, the CPU 81 measures the corneal thickness from the epithelial reflection bright spot 100a and the endothelial reflection bright spot 100b formed in the measurement image 77a. In this manner, upon completion of the second alignment process S300, the corneal thickness can be smoothly measured based on the corneal reflection bright spot 100 formed in the measurement image 77a at that time. Upon completion of the corneal thickness measurement, the CPU 81 measures the subject's intraocular pressure. Specifically, the CPU 81 sprays fluid onto the cornea of ​​the subject's eye E from the testing protrusion 9, thereby measuring the intraocular pressure of the subject's eye E from the deformed shape of the cornea. Then, upon measuring the intraocular pressure of the subject's eye E, the CPU 81 terminates the measurement process.

[0106] (Second embodiment) Next, a second embodiment will be described below. In the description of the second embodiment, only the differences from the first embodiment will be described, and the same reference numerals will be used to designate components having the same functions, and detailed descriptions thereof will be omitted.

[0107] 18 shows the optical system of an ophthalmic apparatus (non-contact tonometry apparatus) 110 according to the second embodiment. The ophthalmic apparatus 1 according to the first embodiment performed the first alignment using a collimated bright spot 96 formed by collimated light and a non-collimated bright spot 98 formed by non-collimated light. In contrast, the ophthalmic apparatus 110 according to the second embodiment performs the first alignment based on light emitted from a light source (infrared light source) 50 of the corneal deformation detection optical system. That is, in the second embodiment, the first alignment is performed using the corneal deformation detection optical system (first optical system).

[0108] Specifically, light (first irradiation light) emitted from an infrared light source 50 serving as a first light source is collimated by a collimator lens 51. After being reflected by a beam splitter 52, the light becomes coaxial with the optical axis L3 of the light-receiving optical system 70b and is projected onto the cornea Ec of the subject's eye E. The light reflected by the cornea Ec becomes coaxial with (coincides with) the optical axis L2 of the light-projecting optical system 70, passes through the lens 53, is reflected by the beam splitter 55, and is received by a photodetector (first image sensor) 57. As will be described in detail later, the photodetector 57 needs to capture a deformation detection image 57a so that the position of the bright spot 111 can be detected. Therefore, at least during the first alignment, the pinhole plate 56 (see FIG. 3) is not placed on the light-receiving optical path of the photodetector 57. For example, the ophthalmic apparatus 110 may use an actuator to remove the pinhole plate 56 from the light receiving optical path during the first alignment and place the pinhole plate 56 on the light receiving optical path when detecting corneal applanation (when measuring intraocular pressure). Furthermore, when detecting corneal applanation without using the pinhole plate 56, the ophthalmic apparatus 110 may perform applanation detection based on the brightness of a specific region (e.g., a central region) of the image captured by the photodetector 57. From the perspective of performing the first alignment, various sensors can be used as the photodetector 57 as long as they can determine the amount of received light and the position of a bright spot. For example, a line sensor, a profile sensor, a two-dimensional CMOS sensor, etc. can be used.

[0109] The light received by the photodetector 57 is reflected on a two-dimensional image (hereinafter referred to as a deformation detection image 57a) as shown in Fig. 19. Here, Fig. 19(a) shows the case where the ophthalmic apparatus 110 is located at the measurement position (i.e., a state where alignment in the Z direction is completed), Fig. 19(b) shows the case where the ophthalmic apparatus 110 has not reached the measurement position (a state where it is too far from the subject's eye E), and Fig. 19(c) shows the case where the ophthalmic apparatus 110 has passed the measurement position and approached the subject's eye E (a state where it is too close to the subject's eye E).

[0110] As shown in FIGS. 19(a) and 19(b), light reflected by the cornea Ec forms a substantially circular bright spot 111 on the deformation detection image 57a. However, the position of the bright spot 111 changes depending on the position of the ophthalmic apparatus 110 in the Z direction. More specifically, as shown in FIG. 19(a), when the ophthalmic apparatus 110 is at the measurement position (ΔWD=0), the center of the bright spot 111 is located approximately in the center of the deformation detection image 57a. On the other hand, as shown in FIG. 19(b), when the ophthalmic apparatus 110 is located in front of the measurement position (ΔWD>0), the center of the bright spot 111 is located offset to the upper side of the deformation detection image 57a. Furthermore, as shown in FIG. 19(c), when the ophthalmic apparatus 110 moves beyond the measurement position and closer to the subject's eye E (ΔWD<0), the center of the bright spot 111 is located offset to the lower side of the deformation detection image 57a.

[0111] Therefore, the CPU 81 of the control unit 80 according to the second embodiment controls the drive unit 4 to perform first alignment based on the position of the bright spot 111 formed on the deformation detection image 57a by the deformation detection light. More specifically, the CPU 81 moves the ophthalmic device 110 in the Z direction so that the center of the bright spot 111 formed on the deformation detection image 57a is positioned at the center of the deformation detection image 57a. When the center of the bright spot 111 is positioned at the center of the deformation detection image 57a, the CPU 81 ends the first alignment and transitions to second alignment. Note that the CPU 81 does not necessarily need to control the drive unit 4 so that the center of the bright spot 111 is positioned at the center of the deformation detection image 57a. For example, the first alignment may be performed based on the edge position of the bright spot 111 formed on the deformation detection image 57a, the balance of high-brightness pixels, or the like.

[0112] As described above, the ophthalmic apparatus 110 according to the second embodiment performs first alignment based on the light emitted by the corneal deformation detection optical system. Due to the characteristics of the corneal deformation detection optical system, the light receiving magnification of the photodetector 57 is lower than that of the corneal thickness measurement optical system. Therefore, the detectable range of the photodetector 57 is wider, and the position of the ophthalmic apparatus 110 in the Z direction can be adjusted over a wider range than with the corneal thickness measurement optical system. Note that once the first alignment is completed, the CPU 81 performs precise alignment (second alignment) based on the light emitted by the corneal thickness measurement optical system, as in the first embodiment.

[0113] (Third embodiment) Next, an ophthalmic apparatus (non-contact intraocular pressure measuring apparatus) 200 according to a third embodiment will be described. In the third embodiment, only differences from the first embodiment will be described, and members having the same functions will be assigned the same reference numerals and detailed descriptions thereof will be omitted.

[0114] 20 is a diagram schematically illustrating an optical system of an ophthalmic apparatus 200 according to a third embodiment. In the third embodiment, a corneal thickness measurement optical system is used to perform first and second alignments. The corneal thickness measurement optical system according to the third embodiment includes a measurement light source (second light source) 202 that irradiates the cornea Ec of the subject's eye E with irradiation light (second irradiation light) from an oblique direction. The corneal thickness measurement optical system further includes an alignment light source (first light source) 203 that irradiates the cornea Ec of the subject's eye E with irradiation light (first irradiation light) from an oblique direction. In other words, the corneal thickness measurement optical system according to the third embodiment also serves as an alignment optical system.

[0115] The measurement light source 202 is provided on the same side as the alignment light source 203 with respect to the examination axis IO of the ophthalmologic apparatus 200 (upper side in FIG. 20 ). As shown in FIG. 20 , light emitted from the measurement light source 202 (hereinafter referred to as measurement light) is projected along the optical axis L so as to be focused on the cornea Ec of the subject's eye E. The measurement light reflected by the cornea Ec of the subject's eye E travels along the optical axis L'. The light emitted from the alignment light source 203 (hereinafter referred to as alignment light) is reflected by the beam splitter 204 and becomes coaxial with the optical axis L of the measurement light. The light is then converted into parallel light by the lens 205 and projected onto the cornea Ec of the subject's eye E. The alignment light reflected by the cornea Ec of the subject's eye E travels along the optical axis L' coaxially with the measurement light.

[0116] Furthermore, the corneal thickness measurement optical system according to the third embodiment receives measurement light and alignment light by a single light receiving element (first image capturing element, second image capturing element) 205. This light receiving element 205 is provided on the opposite side (lower side in FIG. 20 ) of the measurement light source 202 and alignment light source 203 with respect to the examination axis IO of the ophthalmic apparatus 200. The measurement light and alignment light reflected by the cornea Ec of the eye E to be examined are received by the single light receiving element 205.

[0117] FIG. 21 is a comparative diagram schematically illustrating the position where a bright spot occurs due to the cornea. The measurement light irradiated so as to be focused on the cornea Ec forms a bright spot at the apex of the cornea Ec, as shown in FIG. 21(a). On the other hand, the alignment light, which is parallel light, forms a bright spot at the focal position of the cornea Ec. Therefore, the measurement light reflected by the cornea Ec and the alignment light have different image formation positions. Therefore, the ophthalmic apparatus 200 according to the third embodiment includes an element driving unit 206 that moves the light receiving element 205 along the optical axis L'. The element driving unit 206 includes an actuator (not shown). The control unit 80 is electrically connected to the actuator, and the CPU 81 of the control unit 80 controls the operation of the actuator.

[0118] Specifically, when capturing an image of the alignment light, the CPU 81 of the control unit 80 controls the actuator to move the light receiving element 205 along the optical axis L' to a position (first position) where an image of a bright spot formed by the alignment light is formed. When the light receiving element 205 is located at the first position, an image of the bright spot formed by the alignment light can be captured. On the other hand, when receiving the measurement light, the CPU 81 controls the actuator to move the light receiving element 205 along the optical axis L' to a position (second position) where an image of a bright spot formed by the measurement light is formed. When the light receiving element 205 is located at the second position, an image of the bright spot formed by the measurement light can be captured. The second position is closer to the subject's eye E in the direction of the optical axis L' than the first position. The distance between the first position and the second position is set to, for example, approximately 25 mm.

[0119] When performing the first alignment, the CPU 81 positions the light receiving element 205 at a first position. Then, the CPU 81 performs the first alignment based on a bright spot formed by the alignment light on a two-dimensional image captured by the light receiving element 205. That is, the CPU 81 can perform rough alignment of the ophthalmic apparatus 200 in the Z direction based on the alignment light, which is parallel light. After the first alignment is completed, the CPU 81 causes the element driving unit 206 to move the light receiving element 205 to a second position. Then, the CPU 81 performs the second alignment based on a bright spot formed by the measurement light captured by the light receiving element 205 positioned at the second position. At this time, the second alignment is performed based on the measurement light focused on the cornea Ec of the subject's eye E, so that precise alignment of the ophthalmic apparatus 200 in the Z direction can be performed.

[0120] In this way, the ophthalmologic apparatus 200 according to the third embodiment can perform the first alignment and the second alignment using the common light receiving element 205. Therefore, the number of parts can be reduced, and an increase in costs can be avoided.

[0121] In the above-described embodiment, the light-receiving element 205 is configured to move along the optical axis L' in accordance with the imaging positions of the measurement light and alignment light. However, for example, an imaging lens may be removably provided in front of the light-receiving element 205 (on the subject side). The imaging lens may be installed on the optical axis or removed to move the imaging positions of the measurement light and alignment light along the optical axis L'. In this case, the light-receiving element 205 is fixed at a predetermined position on the optical axis L'. Furthermore, a lens with a variable focal length, such as a liquid lens, may be used as the imaging lens. The imaging positions of the measurement light and alignment light may be changed by using such a lens with an adjustable focal length. In this case, the light-receiving element 205 is also fixed at a predetermined position on the optical axis L'.

[0122] IO inspection axis Ec cornea E. Examined eye EO Centered on measured area L1 Collimated spot spacing L2 Non-collimated spot spacing 1 Ophthalmology equipment 4 Drive unit 35 Anterior eye imaging unit (first imaging element) 50 Infrared light source (first light source) 57 Photodetector (first image sensor) 71 Irradiation light source (second light source) 77 Photodetector (second imaging element) 80 Control unit (control section) 96 Collimated Bright Spots 98 non-collimated bright spots 202 Measurement light source (second light source) 203 Alignment light source (first light source) 205 Light receiving element (first imaging element, second imaging element)

Claims

1. A non-contact tonometry device for measuring intraocular pressure of a subject's eye by detecting deformation of the cornea of ​​the subject's eye while aligning an examination axis with the cornea of ​​the subject's eye, comprising: a first optical system that irradiates the subject's eye with first irradiation light including at least parallel light; a second optical system that irradiates the subject's eye with second irradiation light that is focused on the cornea of ​​the subject's eye in order to measure the corneal thickness of the cornea of ​​the subject's eye; a drive unit that moves the non-contact ocular pressure measuring device relative to the subject's eye in a Z direction that is a direction along the examination axis; a control unit, the first optical system includes a first light source that emits light and a first image sensor that receives the first irradiation light reflected by the cornea of ​​the subject's eye, the second optical system includes a second light source that emits light and a second image sensor that receives the second irradiation light reflected by the cornea of ​​the subject's eye, The control unit causes the driving unit to perform a first alignment in the Z direction based on the first irradiation light received by the first imaging element, and then causes the driving unit to perform a second alignment in the Z direction based on the second irradiation light received by the second imaging element.

2. 2. The non-contact intraocular pressure measuring device according to claim 1, the first optical system is configured to form a collimated bright spot by collimated light and a non-collimated bright spot by non-collimated light on a two-dimensional image captured by the first imaging element, The control unit causes the drive unit to perform the first alignment based on the collimated bright spot and the non-collimated bright spot formed on the two-dimensional image.

3. 3. The non-contact intraocular pressure measuring device according to claim 2, the first optical system is configured to form a pair of the collimated bright spots and a pair of the non-collimated bright spots on the two-dimensional image; The control unit controls the drive unit to perform the first alignment based on the distance between the pair of collimated bright spots and the distance between the pair of non-collimated bright spots.

4. 4. The non-contact intraocular pressure measuring device according to claim 1, The control unit changes the timing of transition from the first alignment to the second alignment in accordance with the radius of curvature of the cornea of ​​the subject's eye.

5. 5. The non-contact intraocular pressure measuring device according to claim 4, The control unit calculates a reference value based on the first irradiation light while executing the first alignment, and determines the timing of transition from the first alignment to the second alignment based on the calculated reference value.

6. 6. The non-contact intraocular pressure measuring device according to claim 4 or 5, The control unit estimates the radius of curvature of the cornea of ​​the subject's eye based on a bright spot formed by the first irradiation light on a two-dimensional image captured by the first imaging element.

7. 7. The non-contact intraocular pressure measuring device according to claim 1, The control unit of this non-contact intraocular pressure measurement device stops the second alignment performed by the drive unit if, while the drive unit is performing the second alignment, the center of the measurement area of ​​the test eye becomes more than a predetermined distance away from the examination axis of the test eye and the second imaging element detects the second irradiation light reflected by somewhere other than the cornea of ​​the test eye of the test subject.

8. 8. The non-contact intraocular pressure measuring device according to claim 1, The control unit of this non-contact intraocular pressure measurement device stops the second alignment performed by the drive unit if, while the drive unit is performing the second alignment, a bright spot caused by the first irradiation light is no longer formed on the two-dimensional image captured by the first imaging element, and if the second imaging element detects the second irradiation light reflected by somewhere other than the cornea of ​​the subject's eye.

9. 9. A non-contact intraocular pressure measuring device according to claim 1, When a position where the corneal thickness of the cornea of ​​the test eye is measured is defined as a measurement position among the relative positions of the non-contact ocular pressure measuring device with respect to the test eye in the Z direction, When the Z-direction position of the non-contact ocular pressure measurement device reaches the measurement position while the control unit is causing the drive unit to perform the second alignment, the control unit causes the drive unit to end the second alignment and measures the corneal thickness of the cornea of ​​the test eye based on the second irradiation light reflected by the cornea of ​​the test eye and received by the second imaging element.

10. 2. The non-contact intraocular pressure measuring device according to claim 1, the first optical system is a detection optical system that obliquely irradiates the cornea of ​​the test eye with the first irradiation light, and detects deformation of the cornea of ​​the test eye based on the first irradiation light that is reflected by the cornea of ​​the test eye and received by the first image sensor; The control unit causes the drive unit to perform the first alignment based on the first irradiation light reflected by the cornea of ​​the subject's eye and received by the first imaging element.

11. 2. The non-contact intraocular pressure measuring device according to claim 1, the first optical system is an alignment optical system that obliquely irradiates the first irradiation light onto the cornea of ​​the test eye, the second optical system is configured such that the second light source is provided on the same side as the first light source with respect to the examination axis of the non-contact ocular pressure measurement device, and the second irradiation light is irradiated onto the cornea of ​​the test eye in a state where the second irradiation light is coaxial with the optical axis of the first irradiation light, a first imaging element and a second imaging element that are the same imaging element and are arranged on the opposite side of the examination axis from the first light source and the second light source, and that are capable of receiving the first irradiation light and the second irradiation light.

12. 1. A method for aligning a non-contact tonometry device for measuring intraocular pressure of a subject eye by detecting deformation of the cornea of ​​the subject eye while aligning an examination axis with the cornea of ​​the subject eye, comprising: irradiating the subject's eye with first irradiation light including at least parallel light, and receiving the first irradiation light reflected by the subject's eye with a first image sensor; irradiating the subject's eye with second illumination light that is focused on the cornea of ​​the subject's eye in order to measure the corneal thickness of the cornea of ​​the subject's eye, and receiving the second illumination light reflected by the cornea of ​​the subject's eye with a second image sensor; performing a first alignment by moving the non-contact ocular pressure measurement device relative to the subject's eye in a Z direction, which is a direction along the examination axis, based on the first irradiation light received by the first image sensor; an alignment method in which, after performing the first alignment, a second alignment is performed in which the non-contact tonometry device is moved relative to the subject's eye in the Z direction based on the second irradiation light received by the second imaging element.

13. 13. The alignment method according to claim 12, irradiating the eye to be examined with collimated light and non-collimated light as first irradiation light; An alignment method in which the first alignment is performed based on collimated bright spots formed by the collimated light and non-collimated bright spots formed by non-collimated light on a two-dimensional image captured by the first imaging element.

14. A program for executing alignment of a non-contact tonometry device that measures intraocular pressure of a subject eye by detecting deformation of the cornea of ​​the subject eye while aligning an examination axis with the cornea of ​​the subject eye, a processor included in the non-contact intraocular pressure measuring device, performing a first alignment in which the non-contact ocular pressure measurement device is moved relative to the subject's eye in a Z direction, which is a direction along the examination axis, based on the first irradiation light including at least parallel light that is reflected by the subject's eye and received by a first image sensor; a program for performing the first alignment based on second irradiation light that is focused on the cornea of ​​the test eye in order to measure the corneal thickness of the cornea of ​​the test eye, and that is reflected by the cornea of ​​the test eye and received by a second image sensor, and then performing second alignment by moving the non-contact tonometry device relative to the test eye in the Z direction.

15. 15. The program according to claim 14, The processor further comprises: A program that performs the first alignment based on collimated and non-collimated bright spots formed, respectively, on a two-dimensional image captured by the first imaging element using collimated and non-collimated light irradiated onto the test eye as the first irradiation light.

Images