Corneal measurement device

Abstract

To provide a cornea measuring apparatus which allows the positional shape of pattern light to be projected on a subject eye to be adjusted arbitrarily.SOLUTION: The apparatus comprises: a dot matrix type display (a dot matrix LCD 22) which projects pattern light (a ring pattern light L1) to at least a cornea Ec of a subject eye E and allows the shape of pattern light to be changed arbitrarily; and an imaging optical system 26 which images return light L2 from the subject eye E on which the pattern light is projected by the display and outputs an anterior eye part image D of the subject eye E. The positional shape of the pattern light to be projected on the subject eye E can be arbitrarily adjusted.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a corneal measurement apparatus that measures the cornea of a subject's eye. [Background technology]

[0002] The keratometer (corneal curvature measurement device) described in Patent Document 1 projects a ring-pattern light from a keratinizing light source onto a position of φ3 mm on the cornea of the subject's eye, and captures an image of the anterior segment of the eye by photographing the cornea. The keratometer then measures the corneal radius of curvature (corneal curvature) at a position of φ3 mm on the cornea based on the ring-pattern image, which is a reflected image of the ring-pattern light detected from the anterior segment image. Note that, since curvature and radius of curvature are generally reciprocal to each other, the corneal curvature and radius of curvature are equivalent.

[0003] Furthermore, a corneal topographer (corneal shape measuring device) described in Patent Document 2 projects multiple concentric Placido ring lights onto the cornea from a Placido ring light source and captures an image of the anterior segment of the eye by photographing the cornea. The corneal topographer then detects a Placido ring image, which is a reflected image of the Placido ring lights, from the anterior segment image and measures the corneal shape (corneal curvature distribution or corneal curvature radius distribution) of the cornea based on the Placido ring image. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-146095 [Patent Document 2] Japanese Patent Application Publication No. 2019-166277 Summary of the Invention [Problem to be solved by the invention]

[0005] The keratometer described in Patent Document 1 typically assumes that the corneal radius of curvature of the subject's eye is 8 mm, and adjusts the keratometer ring light source so that a ring pattern light can be projected at a position of φ3 mm on the cornea of the subject's eye. Therefore, if the actual corneal radius of curvature of the subject's eye deviates from 8 mm, the keratometer ring light source cannot project the ring pattern light at a position of φ3 mm on the cornea. As a result, it is impossible to measure the corneal radius of curvature at a position of φ3 mm on the cornea of the subject's eye. Therefore, there is a strong demand for a system that allows the position and shape of the ring pattern light projected onto the subject's eye to be freely adjusted. Similarly, there is a strong demand for a corneal topographer device described in Patent Document 2 that allows the position and shape of the Placido ring light projected onto the subject's eye to be freely adjusted.

[0006] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a corneal measurement apparatus that can arbitrarily adjust the position and shape of pattern light projected onto the subject's eye. [Means for solving the problem]

[0007] A corneal measurement device that achieves the object of the present invention includes a dot matrix display that projects pattern light onto at least the cornea of the subject's eye and is capable of arbitrarily changing the shape of the pattern light, and an imaging optical system that captures the light returning from the subject's eye onto which the pattern light is projected by the display, and outputs an image of the anterior segment of the subject's eye.

[0008] According to this corneal measurement device, by projecting a pattern light onto at least the cornea of the subject's eye using a dot matrix display, it is possible to arbitrarily change the shape of this pattern light, i.e., arbitrarily change the projection position and shape of the pattern light projected onto the cornea.

[0009] In a corneal measurement device according to another aspect of the present invention, the display is a liquid crystal display.

[0010] A corneal measurement device according to another aspect of the present invention includes a corneal radius of curvature calculation unit that calculates the corneal radius of curvature of the subject's eye based on an anterior-segment image output from an imaging optical system, and a first display control unit that controls a display to correct the projection position of the ring pattern light on the cornea to a predetermined target position based on the calculation result of the corneal radius of curvature calculation unit, and when the projection position of the ring pattern light is corrected by the first display control unit, the corneal radius of curvature calculation unit recalculates the corneal radius of curvature based on the anterior-segment image output from the imaging optical system, thereby making it possible to measure the corneal radius of curvature at a desired target position on the cornea of the subject's eye.

[0011] In a corneal measurement device according to another aspect of the present invention, the first display control unit calculates an incident angle of the ring pattern light with respect to the cornea that allows the ring pattern light to be incident on the target position based on the calculation result of the corneal curvature radius calculation unit and the target position, and corrects the projection position based on the calculation result of the incident angle, thereby making it possible to measure the corneal curvature radius at a desired target position on the cornea of the subject's eye.

[0012] In a corneal measurement device according to another aspect of the present invention, the first display control unit repeatedly corrects the projection position and the corneal radius of curvature calculation unit repeatedly calculates the corneal radius of curvature, thereby making it possible to measure the corneal radius of curvature at a desired target position on the cornea of the subject's eye.

[0013] In a corneal measurement device according to another aspect of the present invention, the pattern light is ring pattern light, and the device includes a second display control unit that controls a display to change the ring diameter of the ring pattern light projected onto the cornea multiple times, a first image capture control unit that causes the imaging optical system to capture images of returned light for each ring diameter when the ring diameter is changed by the second display control unit, and a corneal shape calculation unit that calculates the corneal shape of the subject's eye based on anterior segment images captured by the imaging optical system for each ring diameter, thereby enabling more accurate measurement of the corneal shape of the subject's eye.

[0014] A corneal measurement device according to another aspect of the present invention includes a measurement head having a display and an imaging optical system, a drive mechanism for moving the measurement head relative to the eye to be examined along the optical axis direction of the imaging optical system, a second imaging control unit for causing the imaging optical system to capture images of returned light at multiple different imaging positions along the optical axis direction when the measurement head is moved relative to the eye to be examined in the optical axis direction by the drive mechanism, and a corneal shape calculation unit for calculating the corneal shape of the eye to be examined based on anterior eye images captured by the imaging optical system at each imaging position. This makes it possible to more accurately measure the corneal shape of the eye to be examined.

[0015] In a corneal measurement device according to another aspect of the present invention, the display has a display surface that displays a ring pattern, and includes a third display control unit that performs anti-aliasing processing on the ring pattern displayed on the display surface, and the display projects, as pattern light, ring pattern light corresponding to the ring pattern that has been subjected to anti-aliasing processing onto the cornea. This ensures measurement accuracy of the corneal radius of curvature and corneal shape of the subject's eye even when a low-resolution display is used.

[0016] In a corneal measurement device according to another aspect of the present invention, the display includes a corneal shape calculation unit that projects a grid-shaped pattern of light onto the cornea and calculates the corneal shape of the subject's eye based on an anterior segment image output from the imaging optical system, thereby enabling the corneal radius of curvature or corneal shape of the subject's eye to be measured with higher accuracy.

[0017] In a corneal measurement device according to another aspect of the present invention, the display displays an illumination pattern for illuminating the anterior segment of the eye to be examined, the illumination pattern having an area larger than that of a ring pattern used to measure the corneal radius of curvature or corneal shape of the eye to be examined, and projects pattern light corresponding to the illumination pattern onto the anterior segment. This allows the display to also be used as an illumination light source, thereby reducing the number of parts in the corneal measurement device and achieving cost reduction.

[0018] A corneal measurement device according to another aspect of the present invention includes a measurement head having a display and an imaging optical system, and a drive mechanism for moving the measurement head relative to the subject's eye, wherein the display can project alignment light onto the cornea to be used for aligning the measurement head with the subject's eye, and an alignment control unit that, when the alignment light is projected from the display onto the cornea, drives the drive mechanism based on an anterior segment image output from the imaging optical system to align the measurement head with the subject's eye. This allows the display to also serve as an alignment light source, thereby reducing the number of components in the corneal measurement device and achieving cost reduction. Furthermore, the shape and size of the alignment light can be adjusted as desired, thereby improving the robustness of alignment detection.

[0019] In a corneal measurement device according to another aspect of the present invention, the display can project fixation light onto the subject's eye to fixate the eye. This allows the display to double as a fixation light source, thereby reducing the number of components in the corneal measurement device and achieving cost reduction. Furthermore, the light intensity, color, size, and position of the fixation light can be freely changed.

[0020] A corneal measurement device according to another aspect of the present invention includes an objective lens that transmits return light from the subject's eye and emits it to an imaging optical system, a cylindrical lens holding portion that houses the objective lens, and a through-hole formed in the display through which the lens holding portion passes, and the display is fitted and fixed to the outside of the lens holding portion. [Effects of the Invention]

[0021] The present invention can arbitrarily adjust the position and shape of the pattern light projected onto the subject's eye. [Brief explanation of the drawings]

[0022] [Figure 1] FIG. 1 is a schematic diagram of a corneal measurement device according to a first embodiment. [Figure 2]In FIG. 2, reference numeral 2A is a front view of the display surface of the dot matrix LCD as seen from the front side in the Z direction, and reference numeral 2B is an enlarged view of the area enclosed by a dotted circle C on the display surface. [Figure 3] FIG. 1 is a front view of a cornea onto which ring pattern light is projected by a dot matrix LCD. [Figure 4] 10 is an explanatory diagram for explaining a modified example of a ring pattern light projected from a dot matrix LCD onto the cornea Ec. FIG. [Figure 5] FIG. 2 is a functional block diagram of a control device according to the first embodiment. [Figure 6] 10 is an explanatory diagram for explaining the relationship between the corneal curvature radius of the subject's eye, the incident angle of the ring pattern light to the cornea, and the projection position of the ring pattern light on the cornea. FIG. [Figure 7] 10 is an explanatory diagram for explaining the shape correction of the ring pattern on the display surface by the height position calculation unit, more specifically, the correction of the height position of the ring pattern in the radial direction relative to the optical axis. FIG. [Figure 8] 4 is a flowchart showing the flow of corneal curvature measurement of the eye to be examined by the corneal measurement apparatus of the first embodiment. [Figure 9] FIG. 10 is a functional block diagram of a control device of a corneal measurement device according to a second embodiment. [Figure 10] FIG. 10 is an explanatory diagram showing an example of a placido ring displayed on a dot matrix LCD according to the second embodiment. [Figure 11] 10 is an explanatory diagram showing an example of a Placido ring light projected onto the cornea from the dot matrix LCD of the second embodiment. FIG. [Figure 12] Reference numerals XIIA to XIIC are explanatory diagrams for explaining display control of a dot matrix LCD by an LCD control unit in a modification of the second embodiment. [Figure 13] 13A to 13C are diagrams illustrating changes in the ring diameter of the ring pattern light projected onto the cornea in a modification of the second embodiment. [Figure 14] 10 is a flowchart showing a procedure for measuring the corneal shape of the subject's eye in a modified example of the second embodiment. [Figure 15] FIG. 10 is a functional block diagram of a control device of a corneal measurement device according to a third embodiment. [Figure 16] Reference symbols XVIA to XVIC are explanatory diagrams for explaining movement control of the measuring head by the movement control section. [Figure 17] 11 is a flowchart showing a flow of corneal shape measurement of an eye to be examined in the third embodiment. [Figure 18] FIG. 10 is an explanatory diagram for explaining a problem that occurs when a ring pattern is displayed on a dot matrix LCD. [Figure 19] 10 is an explanatory diagram for explaining display control of a ring pattern on a dot matrix LCD by an LCD control unit of a fourth embodiment. FIG. [Figure 20] FIG. 11 is a front view of the display surface of the dot matrix LCD of the fifth embodiment as seen from the front side in the Z direction. [Figure 21] 13 is an explanation showing an example of a grating pattern light projected onto the cornea from the dot matrix LCD of the fifth embodiment. [Figure 22] 10A and 10B are explanatory diagrams for explaining problems that arise when a dot matrix LCD is used as an illumination light source for the anterior segment of a subject's eye. [Figure 23] 23 is a front view of the dot matrix LCD in FIG. 22 as seen from the front side in the Z direction. [Figure 24] FIG. 13 is an explanatory diagram for explaining illumination of the anterior segment of the eye to be examined by a dot matrix LCD of the corneal measurement device of the sixth embodiment. [Figure 25] FIG. 25 is a front view of the dot matrix LCD in FIG. 24 as seen from the front side in the Z direction. [Figure 26] FIG. 2 is a front view of the dot matrix LCD as seen from the front side in the Z direction. [Figure 27] FIG. 10 is an explanatory diagram showing ring pattern light projected onto the cornea from a dot matrix LCD, and is a diagram for explaining the problems that arise when using a dot matrix LCD as an alignment light source for aligning a measurement head with respect to a test eye. [Figure 28]FIG. 10 is a front view of the dot matrix LCD as seen from the front side in the Z direction, showing a state in which a ring pattern for alignment is displayed on the display surface. [Figure 29] FIG. 10 is an explanatory diagram showing alignment light projected onto the cornea Ec from a dot matrix LCD. [Figure 30] FIG. 13 is a front view of an objective lens and a dot matrix LCD of a multifunction peripheral according to an eighth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0023] [First embodiment] 1 is a schematic diagram of a corneal measurement device 10 according to a first embodiment. Of the mutually orthogonal X, Y, and Z directions in the figure, the X direction is the left-right direction, the Y direction is the up-down direction, and the Z direction is the front-to-back direction (also referred to as the working distance direction) parallel to the front direction approaching the subject (subject's eye E) and the rear direction moving away from the subject.

[0024] 1, the corneal measurement device 10 of the first embodiment functions as a corneal curvature measurement device that measures the corneal radius of curvature (corneal curvature) at a predetermined target position (measurement position) on the cornea Ec of the subject's eye E, specifically at a position of φ3 mm (including approximately φ3 mm), and as a corneal shape measurement device that measures the corneal shape (corneal curvature distribution or corneal radius of curvature distribution) of the cornea Ec. Note that the first embodiment will be described taking as an example the measurement of the corneal radius of curvature of the subject's eye E by the corneal measurement device 10.

[0025] <Overall configuration of the corneal measurement device> The corneal measurement device 10 includes a measurement head 12, a drive mechanism 14, an operation unit 16, and a face support unit (not shown) that supports the face of the subject.

[0026] The measurement head 12 accommodates various optical systems and computing devices used to measure the corneal curvature radius of the subject's eye E, which will be described in detail later.

[0027] Although not shown, the drive mechanism 14 is configured by a known actuator that moves the measurement head 12 in each of the X, Y, and Z directions, and holds the measurement head 12 movably in each of the X, Y, and Z directions. By driving the drive mechanism 14 under the control of a control device 30 (described later) or by driving the drive mechanism 14 in response to an operation on an operation unit 16 (described later), it becomes possible to align the measurement head 12 with the subject's eye E in the X, Y, and Z directions (hereinafter simply referred to as alignment).

[0028] The operation unit 16 accepts inputs for various operations of the corneal measurement device 10, such as an operation to start measurement of the corneal curvature radius of the subject's eye E, an operation to manually move the measurement head 12 in the XYZ directions, and an operation to set the corneal measurement device 10.

[0029] The measurement head 12 includes a lens holder 20, a dot matrix LCD 22 which is a dot matrix type liquid crystal display (LCD), an objective lens 24, an imaging optical system 26, a monitor 28, and a control device 30.

[0030] The lens holding part 20 is provided on the front surface (the side of the eye E to be examined) of the measurement head 12 in the Z direction, and is formed in a substantially cylindrical shape extending in the Z direction. An objective lens 24 is housed and held inside this lens holding part 20. In addition, a dot matrix LCD 22 is fitted and fixed to the outside of the lens holding part 20.

[0031] The dot matrix LCD 22, which will be described in detail later, projects ring pattern light L1 used to measure the corneal curvature radius of the subject's eye E onto the cornea Ec of the subject's eye E, and functions as a so-called keratin ring light source (placido ring light source).

[0032] The objective lens 24 transmits the return light L2 from the cornea Ec onto which the ring pattern light L1 is projected by the dot matrix LCD 22, and emits the return light L2 toward the imaging optical system 26. Note that the symbol O1 in the figure indicates the optical axis of the objective lens 24 and the imaging optical system 26.

[0033] Although not shown, the imaging optical system 26 includes one or more lenses, one or more diaphragms, and a CMOS (complementary metal oxide semiconductor) or CCD (charge coupled device) imaging element. The imaging optical system 26 captures the return light L2 incident from the objective lens 24 and outputs an anterior segment image D, which is an observation image of the anterior segment of the subject's eye E, to the control device 30.

[0034] Although not shown in FIG. 1, an alignment optical system 27 (see FIG. 5) is provided within the measurement head 12. The alignment optical system 27 projects alignment light for aligning the measurement head 12 with respect to the subject's eye E onto the cornea Ec. The alignment optical system 27 is a known technique (see, for example, Patent Document 2 above), so a detailed description thereof will be omitted here. Return light L2 from the subject's eye E (cornea Ec) onto which the alignment light is projected is imaged by the imaging optical system 26, and an anterior eye image D is input from this imaging optical system 26 to the control device 30.

[0035] The monitor 28 displays an anterior eye image D of the subject's eye E, measurement results of the corneal curvature radius of the subject's eye E, a setting screen of the corneal measurement device 10, etc. under the control of a control device 30 described below.

[0036] The control device 30 comprehensively controls the operation of each part of the corneal measurement device 10 in response to input operations on the operation unit 16, and also calculates the corneal radius of curvature of the subject's eye E based on the anterior eye image D input from the imaging optical system 26. Furthermore, as will be described in detail later, the control device 30 controls the projection of ring pattern light L1 onto the cornea Ec by the dot matrix LCD 22 in order to measure the corneal radius of curvature at a position of φ3 mm on the cornea Ec regardless of the assumed value (8 mm) of the corneal radius of curvature of the subject's eye E. Note that although the control device 30 is provided inside the measurement head 12 in the first embodiment, the control device 30 may also be provided outside the measurement head 12.

[0037] <Dot matrix LCD> 2, reference numeral 2A is a front view of the display surface 22a of the dot matrix LCD 22 as seen from the front side in the Z direction (the side of the eye E to be examined), and reference numeral 2B is an enlarged view of the area of the display surface 22a (light exit surface) surrounded by a dotted circle C. Fig. 3 is a front view of the cornea Ec onto which the ring pattern light L1 is projected by the dot matrix LCD 22.

[0038] 2, the dot matrix LCD 22 is a monochrome LCD without a color filter, and is provided with an infrared LED (light emitting diode) that emits infrared light (near-infrared light) with a wavelength of 940 nm as a backlight source. The dot matrix LCD 22 has a display surface 22a that can display various patterns, and a through-hole 22b through which the lens holding portion 20 passes.

[0039] A plurality of pixels 23 (dots) are two-dimensionally arranged in the X and Y directions on the display surface 22a. Therefore, a pattern of any shape can be displayed on the display surface 22a under the control of the control device 30. As a result, by adjusting the position and shape of the pattern displayed on the display surface 22a, the projection position and shape of the pattern light projected from the dot matrix LCD 22 onto the cornea Ec can be changed arbitrarily. When measuring the corneal radius of curvature of the subject's eye E, the dot matrix LCD 22 displays a ring pattern LP on the display surface 22a under the control of the control device 30.

[0040] 3, when a ring pattern LP is displayed on the display surface 22a, a ring pattern light L1 corresponding to the ring pattern LP is emitted from the display surface 22a, and this ring pattern light L1 is projected onto the cornea Ec. By projecting the ring pattern light L1 from the dot matrix LCD 22 onto the cornea Ec, it is possible to omit the light guide plate and the diffusion plate provided in a conventional keratinizing light source or the like.

[0041] The shape of the ring pattern LP displayed on the display surface 22a, for example, the ring diameter, can be changed arbitrarily. Therefore, by changing the ring diameter of the ring pattern LP displayed on the display surface 22a, the incident angle of the ring pattern light L1 from the dot matrix LCD 22 to the cornea Ec can be changed arbitrarily. As a result, the projection position of the ring pattern light L1 projected onto the cornea Ec (the ring diameter of the ring pattern light L1 on the cornea Ec) can be changed arbitrarily (see FIGS. 6 and 7).

[0042] The ring diameter of the ring pattern LP initially displayed on the display surface 22a is adjusted to a size that enables the ring pattern light L1 to be projected onto a position of φ3 mm on the cornea Ec of the subject's eye E, assuming that the subject's eye E has a corneal radius of curvature of 8 mm. Then, under the control of the control device 30 (described later), the dot matrix LCD 22 corrects the ring diameter of the ring pattern LP on the display surface 22a so that the ring pattern light L1 can be projected onto a position of φ3 mm on the cornea Ec even if the corneal radius of curvature of the subject's eye E deviates from the assumed value of 8 mm.

[0043] Fig. 4 is an explanatory diagram illustrating a modified example of the ring light pattern L1 projected from the dot matrix LCD 22 onto the cornea Ec. In Figs. 3 and 4, a continuous ring pattern LP is displayed on the display surface 22a, and a continuous ring light pattern L1 is projected from this display surface 22a onto the cornea Ec. However, the shapes of the ring pattern LP and the ring light pattern L1 are not particularly limited as long as the corneal curvature radius of the subject's eye E can be measured. For example, although not shown, an intermittent ring pattern LP composed of a plurality of circular dots may be displayed on the display surface 22a, and the intermittent ring light pattern L1 may be projected from the display surface 22a onto the cornea Ec, as shown in Fig. 4. The projection position (ring diameter) of this ring light pattern L1 can also be changed arbitrarily.

[0044] <Control device> 5 is a functional block diagram of the control device 30 according to the first embodiment. As shown in FIG. 5, the control device 30 includes an arithmetic circuit configured with various processors, memories, and the like. The various processors include a central processing unit (CPU), a graphics processing unit (GPU), an application specific integrated circuit (ASIC), and a programmable logic device (e.g., a simple programmable logic device (SPLD), a complex programmable logic device (CPLD), and a field programmable gate array (FPGA)). The various functions of the control device 30 may be implemented by a single processor or by multiple processors of the same or different types.

[0045] The control device 30 executes a control program read from a storage unit (not shown) to function as an imaging control unit 32, an alignment control unit 34, a corneal curvature radius calculation unit 36, a monitor control unit 38, and an LCD control unit 40. Note that what is described as a "unit" of the control device 30 may also be a "circuit," a "device," or a "equipment." In other words, what is described as a "unit" may be composed of firmware, software, hardware, or a combination of these.

[0046] The imaging control unit 32 controls the imaging of the return light L2 by the imaging optical system 26. For example, when an operation to start measurement of the corneal radius of curvature is performed on the operation unit 16, the imaging control unit 32 causes the imaging of the return light L2 by the imaging optical system 26 and the output of the anterior eye image D continuously (continuously). As a result, during alignment, the anterior eye image D of the subject's eye E (cornea Ec) onto which alignment light is projected by the alignment optical system 27 is continuously output from the imaging optical system 26 to the control device 30. Furthermore, during corneal radius of curvature measurement, the anterior eye image D of the subject's eye E (cornea Ec) onto which ring pattern light L1 is projected by the dot matrix LCD 22 is continuously output from the imaging optical system 26 to the control device 30.

[0047] When aligning the measurement head 12 with the subject's eye E, the alignment control unit 34 controls the alignment optical system 27 to project alignment light onto the cornea Ec, and acquires anterior segment images D of the subject's eye E that are continuously output from the imaging optical system 26. Then, the alignment control unit 34 detects the alignment of the measurement head 12 in the X, Y, and Z directions with respect to the subject's eye E, based on the anterior segment images D input from the imaging optical system 26. Note that specific alignment detection methods are well known techniques, and therefore detailed explanations will be omitted. Next, the alignment control unit 34 drives the drive mechanism 14 to perform alignment in the X, Y, and Z directions, based on the alignment detection results in the X, Y, and Z directions.

[0048] The corneal curvature radius calculation unit 36 detects a ring image corresponding to the ring pattern light L1 from the anterior segment image D based on the anterior segment image D output from the imaging optical system 26 when measuring the corneal curvature radius of the subject's eye E, and calculates the corneal curvature radius of the subject's eye E using a known method based on the detection result of this ring image. In this way, the corneal curvature radius at the position on the cornea Ec where the ring pattern light L1 is projected (assumed position is φ3 mm) is measured.

[0049] In addition, the corneal curvature radius calculation unit 36 repeatedly recalculates the corneal curvature radius of the subject's eye E based on the anterior segment image D newly output from the imaging optical system 26 every time the projection position of the ring pattern light L1 projected onto the cornea Ec is corrected by the LCD control unit 40 described below.

[0050] The monitor control unit 38 controls the display on the monitor 28. At least during alignment and measurement of the corneal radius of curvature of the subject's eye E, the monitor control unit 38 causes the monitor 28 to display a moving image of the anterior eye image D based on the anterior eye image D continuously output from the imaging optical system 26. Furthermore, when the corneal radius of curvature calculation unit 36 calculates the corneal radius of curvature of the subject's eye E, the monitor control unit 38 causes the monitor 28 to display the calculation result.

[0051] In the first embodiment, the LCD control unit 40 corresponds to the first display control unit of the present invention. The LCD control unit 40 operates during measurement of the corneal radius of curvature of the subject's eye E to control the display of the ring pattern LP by the dot matrix LCD 22, that is, to control the projection position (ring diameter) of the ring pattern light L1 projected from the dot matrix LCD 22 onto the cornea Ec.

[0052] 6 is an explanatory diagram for explaining the relationship among the corneal radius of curvature of the subject's eye E, the incident angle of the ring light pattern L1 with respect to the cornea Ec, and the projection position of the ring light pattern L1 on the cornea Ec. As shown in FIG. 6, when the corneal radius of curvature is "r," the incident angle (also referred to as the angle of view) of the ring light pattern L1 with respect to the cornea Ec is "2θ," and the projection position of the ring light pattern L1 on the cornea Ec (height position from the optical axis O1 with the optical axis O1 as the reference) is "h" (2h=φ), these relationships are expressed by the following [Mathematical Expression 1].

[0053]

number

[0054] As shown in Figures 5 and 6, first, the LCD control unit 40 assumes that the corneal curvature radius of the subject's eye E is 8 mm, and sets a position of φ3 mm on the cornea Ec of the subject's eye E as the target position, and controls the incident angle of the ring pattern light L1 with respect to the cornea Ec, i.e., the shape of the ring pattern LP on the display surface 22a, so that the ring pattern light L1 is projected at the target position.

[0055] Specifically, based on the above-mentioned [Equation 1], the LCD control unit 40 adjusts the radial height position H (see FIG. 7) of the ring pattern LP within the display surface 22a so that the ring pattern light L1 is projected from the dot-matrix LCD 22 onto the cornea Ec at an incident angle (2θ) that achieves 2h(φ)=3 mm assuming r=8 mm. This causes the dot-matrix LCD 22 to project the ring pattern light L1 onto the cornea Ec, the imaging optical system 26 to capture the returned light L2 and output the anterior eye image D, and the corneal radius of curvature calculation unit 36 to calculate the corneal radius of curvature. Here, if the actual corneal radius of curvature of the subject's eye E deviates from the assumed value (r=8 mm), the corneal radius of curvature is measured at a position on the cornea Ec that is shifted from 2h(φ)=3 mm.

[0056] Next, the LCD control unit 40 uses the calculation result of the corneal radius of curvature by the corneal radius of curvature calculation unit 36 to control the dot matrix LCD 22 to adjust the incident angle of the ring pattern light L1 with respect to the cornea Ec so that the ring pattern light L1 is projected at a position of φ3 mm on the cornea Ec even if the corneal radius of curvature deviates from the expected value. Therefore, the LCD control unit 40 functions as an incident angle calculation unit 40a and a height position calculation unit 40b when measuring the corneal radius of curvature of the subject's eye E.

[0057] The incident angle calculation unit 40a calculates the incident angle (2θ) that realizes 2h(φ)=3 mm using the above formula (1) based on the calculation result "r" of the corneal radius of curvature by the corneal radius of curvature calculation unit .

[0058] 7 is an explanatory diagram for explaining the shape correction of the ring pattern LP on the display surface 22a by the height position calculation unit 40b, more specifically, the correction of the height position H of the ring pattern LP in the radial direction with respect to the optical axis O1. Note that the reference numeral 25a in the figure denotes the aperture of the imaging optical system 26.

[0059] As shown in Figure 7 and the previously described Figures 5 and 6, based on the calculation result of the incident angle (2θ) by the incident angle calculation unit 40a, the height position calculation unit 40b adjusts the shape (ring diameter) of the ring pattern LP within the display surface 22a so that this incident angle is realized, i.e., adjusts the height position H in the radial direction (XY direction) of the ring pattern LP relative to the optical axis O1.

[0060] Specifically, if the Z-direction distance between the corneal apex of the test eye E and the dot matrix LCD 22 is "D" (a known value), the Z-direction distance between the corneal apex and the incident point Q of the ring pattern light L1 on the cornea Ec is "d" (see Figure 6), and the radial distance between the incident point Q and the optical axis O1 as described above is "h," the incident angle is expressed by the following equation [2].

[0061]

number

[0062] Furthermore, "θ" in equation (2) is expressed by the following equation (3), and "d" is expressed by the following equation (4).

[0063]

number

[0064]

number

[0065] Here, "r" in the above formulas (3) and (4) is the result of calculation of the corneal radius of curvature by the corneal radius of curvature calculation unit 36, and "h" is a value that satisfies 2h = φ3 mm. Therefore, the height position calculation unit 40b can calculate the angle of incidence (2θ) that satisfies 2h = φ3 mm using the above formula (3). The height position calculation unit 40b can also calculate "d" using the above formula (4). The height position calculation unit 40b then substitutes the calculation results of "2θ" and "d" and the known values "D" and "h" into the following formula (5), which is a modification of the above formula (2), to calculate the height position (H) corresponding to the angle of incidence (2θ) that achieves 2h(φ) = 3 mm.

[0066]

number

[0067] The LCD control unit 40 adjusts the ring diameter of the ring pattern LP displayed on the display surface 22a to the height position (H) based on the calculation result of the height position (H) by the height position calculation unit 40b. As a result, the ring pattern light L1 is projected from the dot matrix LCD 22 at an incident angle (2θ) that achieves 2h(φ)=3 mm on the cornea Ec, and the projection position of the ring pattern light L1 on the cornea Ec is corrected to φ3 mm. Note that the "correction of the projection position" here also includes correction of the shape of the ring pattern light L1 on the cornea Ec, i.e., correction of the ring diameter of the ring pattern light L1.

[0068] When the projection position of the ring pattern light L1 on the cornea Ec is corrected by the LCD control unit 40, the imaging optical system 26 captures the returned light L2 and outputs the anterior eye image D, and the corneal curvature radius calculation unit 36 recalculates the corneal curvature radius.

[0069] Thereafter, until the calculation result of the corneal radius of curvature by the corneal radius of curvature calculation unit 36 converges, the LCD control unit 40 corrects the projection position of the ring pattern light L1, the imaging optical system 26 captures the returned light L2 and outputs the anterior eye image D, and the corneal radius of curvature calculation unit 36 recalculates the corneal radius of curvature. Then, when the calculation result of the corneal radius of curvature converges, the corneal radius of curvature calculation unit 36 determines the value as the measurement result of the corneal radius of curvature of the subject's eye E. Note that the corneal radius of curvature calculation unit 36 may calculate the corneal radius of curvature using the above-mentioned [Equation 1] based on the calculation result of the final incident angle (2θ) by the incident angle calculation unit 40a.

[0070] [Operation of the first embodiment] 8 is a flowchart showing the flow of corneal curvature measurement of the subject's eye E by the corneal measurement device 10 of the first embodiment configured as described above. As shown in Fig. 8, after the subject's face is supported by a face support unit (not shown), the examiner performs a measurement start operation on the operation unit 16 (step S1). In response to this measurement start operation, the alignment optical system 27 projects alignment light onto the cornea Ec, the imaging optical system 26 captures the returned light L2 and outputs an anterior eye image D, and the alignment control unit 34 performs alignment in the X, Y, and Z directions.

[0071] When the alignment is complete, the LCD control unit 40 controls the dot-matrix LCD 22 to display a ring pattern LP on the display surface 22a so that the ring pattern light L1 is projected at a position of φ3 mm on the cornea Ec of the subject's eye E, which has a corneal curvature radius of 8 mm (step S2). As a result, the ring pattern light L1 is projected from the dot-matrix LCD 22 onto the cornea Ec (step S3), and the imaging optical system 26 continuously captures the returned light L2 and outputs an anterior-segment image D (step S4). The anterior-segment image D output from the imaging optical system 26 is input to the corneal curvature radius calculation unit 36 and the monitor control unit 38, and the monitor control unit 38 displays the anterior-segment image D on the monitor 28.

[0072] Next, the corneal curvature radius calculation unit 36 calculates the corneal curvature radius at the projection position of the ring pattern light L1 on the cornea Ec based on the anterior eye image D input from the imaging optical system 26, and outputs the calculation result to the monitor control unit 38 and the incident angle calculation unit 40a (step S5). As a result, the calculation result of the corneal curvature radius of the subject's eye E is displayed on the monitor 28 by the monitor control unit 38.

[0073] Furthermore, based on the calculation result of the corneal radius of curvature input from the corneal radius of curvature calculation unit 36, the incident angle calculation unit 40a recalculates the incident angle (2θ) of the ring pattern light L1 with respect to the cornea Ec so as to realize 2h(φ)=3 mm using the above [Equation 1], and outputs the recalculation result to the height position calculation unit 40b (step S6).

[0074] Then, based on the calculation result of the incident angle (2θ) input from the incident angle calculation unit 40a, the height position calculation unit 40b calculates the radial height position (H) of the ring pattern LP using the above equations [Equation 2] to [Equation 5] so as to realize this incident angle (step S7).

[0075] When the calculation of the height position (H) by the height position calculation unit 40b is completed, the LCD control unit 40 controls the dot matrix LCD 22 based on the calculation result to correct the ring diameter of the ring pattern LP on the display surface 22a to the height position (H). As a result, the projection position (ring diameter) of the ring pattern light L1 onto the cornea Ec is corrected to a position of φ3 mm on the cornea Ec (step S8).

[0076] Once the correction of the projection position of the ring pattern light L1 is completed, the imaging optical system 26 again captures the return light L2 and outputs the anterior eye image D (step S9), and the corneal curvature radius calculation unit 36 recalculates the corneal curvature radius (step S10).

[0077] Thereafter, the processes from step S6 to step S10 described above are repeatedly executed until the calculation result of the corneal radius of curvature by the corneal radius of curvature calculation unit 36 converges (step S11). Then, when the calculation result of the corneal radius of curvature converges, the corneal radius of curvature calculation unit 36 determines the value as the measurement result of the corneal radius of curvature of the subject's eye E, or calculates the corneal radius of curvature using the above-mentioned [Equation 1] based on the final calculation result of the incident angle by the incident angle calculation unit 40a. Then, the measurement result of the corneal radius of curvature of the subject's eye E is displayed on the monitor 28 by the monitor control unit 38.

[0078] As described above, in the first embodiment, by projecting the ring light pattern L1 onto the cornea Ec from the dot matrix LCD 22, it is possible to arbitrarily adjust the projection position (including the shape such as the ring diameter) of the ring light pattern L1 projected onto the cornea Ec of the subject's eye E. As a result, it is possible to measure the corneal radius of curvature at a desired position (φ3 mm) on the cornea Ec, regardless of the corneal radius of curvature of the subject's eye E.

[0079] In the first embodiment described above, the corneal curvature radius of the test eye E is measured at a position of φ3 mm on the cornea Ec by the corneal measurement device 10. However, the present invention can also be applied to cases where an arbitrary position on the cornea Ec other than φ3 mm (e.g., φ1 mm, φ2 mm, φ4 mm, ...) is set as the target position and the corneal curvature radius is measured at this target position.

[0080] [Second embodiment] 9 is a functional block diagram of the control device 30 of the corneal measurement device 10 of the second embodiment. In the above first embodiment, the corneal curvature radius measurement of the subject's eye E by the corneal measurement device 10 has been described as an example, but in the second embodiment, the corneal shape measurement of the subject's eye E by the corneal measurement device 10 will be described.

[0081] The corneal measurement device 10 of the second embodiment has basically the same configuration as the corneal measurement device 10 of the first embodiment, except that the LCD control unit 40 of the control device 30 has some different functions and the control device 30 functions as a corneal shape calculation unit 42. Therefore, parts that are the same in function or configuration as those of the first embodiment are given the same reference numerals and their description will be omitted.

[0082] Fig. 10 is an explanatory diagram showing an example of the Placido ring LPM displayed on the dot matrix LCD 22 of the second embodiment. Fig. 11 is an explanatory diagram showing an example of the Placido ring light L1M projected onto the cornea Ec from the dot matrix LCD 22 of the second embodiment.

[0083] 10 and the above-described FIG. 9, when an operation for measuring the corneal shape of the subject's eye E is performed using the operation unit 16, the LCD control unit 40 of the second embodiment controls the dot-matrix LCD 22 to display the Placido ring LPM, which is a concentric and multiple (double or more) ring pattern LP, on the display surface 22a. As a result, as shown in FIG. 11, Placido ring light L1M, which is composed of the concentric and multiple ring pattern light L1, is projected from the dot-matrix LCD 22 onto the subject's eye E. Then, return light L2 from the cornea Ec onto which the Placido ring light L1M is projected, enters the imaging optical system 26 through the objective lens 24, and the imaging of the return light L2 by the imaging optical system 26 and the output of an anterior-segment image D are performed, as in the first embodiment.

[0084] 9, the corneal shape calculation unit 42 detects ring images corresponding to the respective ring pattern lights L1 of the Placido ring light L1M from the anterior-segment image D based on the anterior-segment image D output from the imaging optical system 26 during corneal shape measurement of the subject's eye E, and calculates the corneal shape of the subject's eye E by a known method based on the detection results of each ring image. The calculation result of the corneal shape of the subject's eye E by the corneal shape calculation unit 42 is displayed on the monitor 28 by the monitor control unit 38.

[0085] As described above, in the second embodiment, it is possible to measure the corneal shape of the subject's eye E by projecting the Placido ring light L1M onto the cornea Ec from the dot matrix LCD 22. Furthermore, since it is possible to switch between the measurement of the corneal radius of curvature and the measurement of the corneal shape of the subject's eye E simply by switching the pattern displayed on the dot matrix LCD 22, it is possible to switch between the measurement of the corneal radius of curvature and the measurement of the corneal shape easily and at low cost.

[0086] [Modification of the second embodiment] In the second embodiment, the dot matrix LCD 22 projects Placido ring light L1M onto the cornea Ec, and the imaging optical system 26 captures the returned light L2 from the cornea Ec to obtain an anterior-segment image D, which is used to measure the corneal shape of the subject's eye E. In this case, the smaller the pitch of each ring pattern light L1 constituting the Placido ring light L1M, the more accurately the corneal shape of the subject's eye E can be measured. However, if the pitch of each ring pattern light L1 is smaller than the resolving power (resolution) of the imaging optical system 26, the ring images cannot be detected accurately from the anterior-segment image D, resulting in a large measurement error in the corneal shape.

[0087] Therefore, in the modified example of the second embodiment, the ring light patterns L1 constituting the Placido ring light L1M are projected onto the cornea Ec in order, that is, projected onto the cornea Ec with a time difference, thereby making it possible to measure the accurate corneal shape of the subject's eye E even if the pitch of the ring light patterns L1 is smaller than the resolving power of the imaging optical system 26. Note that the modified example of the second embodiment has basically the same configuration as the second embodiment described above, and therefore, the same reference numerals are used to designate components that are the same in function or configuration as those in the above embodiments, and their description will be omitted.

[0088] Reference symbols XIIA to XIIC in Fig. 12 are explanatory diagrams for explaining display control of the dot matrix LCD 22 by the LCD control unit 40 in the modified example of the second embodiment. Reference symbols XIIIA to XIIIC in Fig. 13 are explanatory diagrams for explaining changes in the ring diameter of the ring pattern light L1 projected onto the cornea Ec in the modified example of the second embodiment.

[0089] As shown by reference numerals XIIA to XIIC in Fig. 12, the LCD control unit 40 of the second embodiment corresponds to the second display control unit of the present invention and controls the dot-matrix LCD 22 in response to an operation to start corneal shape measurement using the operation unit 16 to display one ring pattern LP on the display surface 22a and change the ring diameter of this ring pattern LP multiple times. Specifically, the LCD control unit 40 sequentially changes the ring diameter of the ring pattern LP displayed on the display surface 22a to the ring diameters of the ring patterns LP constituting the desired Placido ring LPM. As a result, ring pattern light L1 with different ring diameters is projected sequentially onto the cornea Ec, as shown by reference numerals XIIIA to XIIIC in Fig. 13.

[0090] In addition, if the ring diameter of each ring pattern light L1 projected from the dot matrix LCD 22 onto the cornea Ec, i.e., the projection position on the cornea Ec (e.g., φ1 mm, φ2 mm, φ3 mm, ...), is predetermined, correction similar to that in the first embodiment described above may be performed for each ring diameter (projection position) of the ring pattern light L1.

[0091] An imaging control unit 32 (corresponding to the first imaging control unit of the present invention) of the modified second embodiment controls the imaging optical system 26 to repeatedly capture the return light L2 from the cornea Ec by the imaging optical system 26 and output an anterior eye image D for each ring diameter of the ring pattern light L1 projected onto the cornea Ec. This allows an anterior eye image D corresponding to each ring diameter of the ring pattern light L1 to be obtained. These anterior eye images D are equivalent to the anterior eye image D of the subject's eye E in which the Placido ring light L1M is projected onto the cornea Ec as shown in FIG. 11 described above.

[0092] The corneal shape calculation unit 42 detects ring images corresponding to the ring pattern light L1 from the anterior eye images D captured by the imaging optical system 26 for each different ring diameter of the ring pattern light L1, and calculates the corneal shape of the test eye E based on the detection results of the ring images in each anterior eye image D using a known method similar to that of the second embodiment described above.

[0093] Fig. 14 is a flowchart showing the flow of corneal shape measurement of the subject's eye E in a modified example of the second embodiment. As shown in Fig. 14, when the examiner performs a measurement start operation on the operation unit 16 (step S1), the above-mentioned alignment is executed. Then, similar to the corneal curvature measurement of the first embodiment shown in Fig. 8, the following steps are executed: displaying a ring pattern LP on the dot matrix LCD 22 (step S2), projecting a ring pattern light L1 from the dot matrix LCD 22 onto the cornea Ec (step S3), and capturing an image of the returned light L2 by the imaging optical system 26 and outputting an anterior eye image D (step S4).

[0094] At this time, the processing from step S5 to step S8 similar to that of the first embodiment shown in Figure 8 may be repeatedly executed to correct the projection position of the ring pattern LP projected from the dot matrix LCD 22 onto the cornea Ec to the desired target position.

[0095] Next, the LCD control unit 40 controls the dot matrix LCD 22 to change the ring diameter of the ring pattern LP displayed on the display surface 22a (YES in step S4A, step S4B). As a result, the ring pattern light L1 after the ring diameter change is projected from the dot matrix LCD 22 onto the cornea Ec (step S3), and the imaging optical system 26 captures the returned light L2 and outputs the anterior-segment image D again (step S4).

[0096] Thereafter, the processes of steps S4B, S3, and S4 are repeatedly executed until the anterior-eye-segment images D are captured for each of the ring pattern light L1 corresponding to all the remaining ring diameters (NO in step S4A). As a result, anterior-eye-segment images D captured for each of the different ring diameters of the ring pattern light L1, i.e., an image equivalent to the anterior-eye-segment image D onto which the Placido ring light L1M is projected, can be obtained (YES in step S4A).

[0097] Next, the corneal topography calculation unit 42 detects a ring image corresponding to the ring pattern light L1 for each anterior-segment image D based on the anterior-segment images D captured for each different ring diameter of the ring pattern light L1. Because each anterior-segment image D contains only one ring image, it is possible to detect a ring image from each anterior-segment image D regardless of the resolving power of the imaging optical system 26. Then, the corneal topography calculation unit 42 calculates the corneal topography of the subject's eye E based on the detection result of the ring image from each anterior-segment image D (step S5A). The calculation result of the corneal topography of the subject's eye E is displayed on the monitor 28 by the monitor control unit 38.

[0098] As described above, in the modification of the second embodiment, the dot matrix LCD 22 is controlled to change the ring diameter of the ring light pattern L1 projected onto the subject's eye E, and the imaging optical system 26 is caused to capture anterior-segment images D for each different ring diameter, thereby eliminating the need to detect multiple ring images from one anterior-segment image D. This makes it possible to accurately detect ring images from each anterior-segment image D even when the pitch of each ring light pattern L1 is smaller than the resolving power of the imaging optical system 26. As a result, it is no longer necessary to make the pitch of each ring light pattern L1 constituting the Placido ring light L1M larger than the resolving power of the imaging optical system 26, as in the second embodiment, and therefore the corneal shape of the subject's eye E can be measured more accurately than in the second embodiment.

[0099] [Third embodiment] 15 is a functional block diagram of the control device 30 of the corneal measurement device 10 of the third embodiment. In the modified example of the second embodiment, the ring diameter of the ring pattern LP displayed on the display surface 22a of the dot matrix LCD 22 is changed to obtain anterior eye images D captured for each of different ring diameters of the ring pattern light L1, but in the third embodiment, the distance between the subject's eye E and the measurement head 12 is changed.

[0100] 15, the corneal measurement device 10 of the third embodiment has basically the same configuration as the corneal measurement device 10 of each of the above-mentioned embodiments, except that the control device 30 functions as a movement control unit 44 and the functions of the imaging control unit 32 and the LCD control unit 40 are partially different. Therefore, parts that are the same in function or configuration as those of the above-mentioned embodiments are given the same reference numerals and their description will be omitted.

[0101] Reference numerals XVIA to XVIC in Fig. 16 are explanatory diagrams for explaining movement control of the measurement head 12 by the movement control unit 44. As shown in Fig. 16 and the already-described Fig. 15, the movement control unit 44 controls the drive mechanism 14 in response to an operation to start measurement of the corneal shape on the operation unit 16, and moves the measurement head 12 relative to the subject's eye E in the optical axis direction along the optical axis O1, i.e., in the Z direction. Note that although Fig. 16 shows the measurement head 12 being moved from the subject side to the examiner side, it may also be moved from the examiner side to the subject side.

[0102] In the third embodiment, the LCD control unit 40 controls the dot-matrix LCD 22 in response to the measurement start operation described above to display on the display surface 22a a ring pattern LP capable of projecting a ring light pattern L1 at a position on the cornea Ec with a diameter of, for example, 3 mm (or a diameter other than 3 mm). This causes the ring light pattern L1 to be projected onto the cornea Ec from the dot-matrix LCD 22. In this state, the driving mechanism 14 moves the measurement head 12 relative to the subject's eye E in the Z direction, thereby changing the angle of incidence of the ring light pattern L1 incident on the cornea Ec from the dot-matrix LCD 22. As a result, the ring diameter (projection position) of the ring light pattern L1 projected onto the cornea Ec can be changed in accordance with the relative movement of the measurement head 12 relative to the subject's eye E in the Z direction. Note that if the ring light pattern L1 cannot be projected onto the cornea Ec with a desired ring diameter simply by moving the measurement head 12 relative to the Z direction, the ring diameter of the ring light pattern L1 may be changed at the same time, as described in the modification of the second embodiment.

[0103] The imaging control unit 32 (corresponding to the second imaging control unit of the present invention) of the third embodiment causes the imaging optical system 26 to capture the return light L2 and output the anterior eye image D at multiple imaging positions along the Z direction when the driving mechanism 14 moves the measurement head 12 relative to the subject's eye E in the Z direction. As a result, similar to the modified example of the second embodiment, anterior eye images D captured for each of different ring diameters of the ring pattern light L1 can be obtained. As a result, the corneal shape calculation unit 42 can calculate the corneal shape of the subject's eye E.

[0104] Fig. 17 is a flowchart showing the flow of corneal shape measurement of the subject's eye E in the third embodiment. As shown in Fig. 17, when the examiner performs a measurement start operation on the operation unit 16 (step S1), alignment is performed in the same manner as in the modified example of the second embodiment (see Fig. 14) described above, and the measurement head 12 is positioned at the initial imaging position with respect to the subject's eye E.

[0105] Once alignment is complete, the dot matrix LCD 22 displays the ring pattern LP (step S2), the dot matrix LCD 22 projects the ring pattern light L1 onto the cornea Ec (step S3), and the imaging optical system 26 captures the return light L2 and outputs the anterior eye image D (step S4).

[0106] Next, the movement control unit 44 drives the drive mechanism 14 to start moving the measurement head 12 in the Z direction relative to the subject's eye E (step S4C). Then, the imaging control unit 32 repeatedly controls the imaging optical system 26 to capture the return light L2 and output the anterior eye image D each time the drive mechanism 14 moves the measurement head 12 to the remaining imaging positions in the Z direction (step S4D, NO in step S4E). This allows for the acquisition of anterior eye images D captured for each of the different ring diameters of the ring pattern light L1, and which are equivalent to the anterior eye image D projected with the Placido ring light L1M. Note that each time the measurement head 12 is moved to an imaging position, the LCD control unit 40 may simultaneously change the ring diameter of the ring pattern light L1 projected onto the cornea Ec, as necessary.

[0107] When the imaging optical system 26 has completed capturing images of the return light L2 at all imaging positions, the movement control unit 44 stops the relative movement of the measurement head 12 by the drive mechanism 14 (YES in step S4E). Next, the corneal shape calculation unit 42 calculates the corneal shape of the subject's eye E based on the anterior eye image D for each ring pattern light L1 having a different ring diameter, as in the modified example of the second embodiment described above (step S5A).

[0108] As described above, in the third embodiment, the measurement head 12 is moved relative to the test eye E in the Z direction, and the imaging optical system 26 captures the return light L2 at multiple imaging positions along the Z direction, thereby achieving the same effect as the modified example of the second embodiment.

[0109] In the above third embodiment, the measurement head 12 is moved in the Z direction by the drive mechanism 14, but for example, the face support part (not shown) may be moved in the Z direction, and the method of moving the measurement head 12 relative to the test eye E in the Z direction is not particularly limited.

[0110] [Fourth embodiment] Fig. 18 is an explanatory diagram for explaining the problem when displaying the ring pattern LP on the dot matrix LCD 22. Note that reference numeral XVIIIA in Fig. 18 is a front view of the display surface 22a of the dot matrix LCD 22 as seen from the front side in the Z direction (the side of the eye E to be examined), and reference numeral XVIIIB is an enlarged view of the area surrounded by the dotted circle D1 on the display surface 22a.

[0111] In each of the above embodiments (except for the second embodiment), a ring pattern LP is displayed on the display surface 22a of the dot matrix LCD 22, and a ring pattern light L1 is projected from the dot matrix LCD 22 onto the cornea Ec. In this case, as shown by reference numerals XVIIIA and XVIIIB in Fig. 18 , if the resolution of the dot matrix LCD 22 is low, jaggies will occur in the ring pattern LP displayed on the display surface 22a, i.e., in the ring pattern light L1 projected onto the cornea Ec. As a result, the accuracy with which the corneal curvature radius calculation unit 36 detects the ring image from the anterior eye image D will decrease, and the accuracy with which the corneal curvature radius (keratomileus value) of the subject's eye E will also decrease.

[0112] The required accuracy of the corneal radius of curvature (keratomileusis value) specified by the ISO (International Organization for Standardization) is ±0.03 mm. For example, in the previously described FIGS. 6 and 7, if D = 65 mm, 2h = 3 mm, and r = 10 mm, H = 41.14 mm. However, if "H" deviates by approximately 0.12 mm, "r" will be measured with a deviation of 0.03 mm. For this reason, the resolution of the dot matrix LCD 22 must be sufficiently smaller than 0.12 mm. However, for example, the resolution of the dot matrix LCD 22 used in each of the above embodiments is 0.18 mm, which is lower than 0.12 mm.

[0113] Therefore, in the corneal measurement device 10 of the fourth embodiment, the resolution of the ring pattern LP displayed on the dot matrix LCD 22 is artificially increased so that measurement accuracy of the corneal curvature radius (keratomic value) of the subject's eye E can be ensured even when a low-resolution dot matrix LCD 22 is used. Note that the corneal measurement device 10 of the fourth embodiment has basically the same configuration as the corneal measurement devices 10 of the above embodiments, except for a partial difference in the function of the LCD control unit 40. Therefore, components that are the same in function or configuration as those of the above embodiments are assigned the same reference numerals and their description will be omitted.

[0114] Fig. 19 is an explanatory diagram for explaining display control of the ring pattern LP of the dot matrix LCD 22 by the LCD control unit 40 of the fourth embodiment. Note that reference numeral XIXA in Fig. 19 is a front view of the display surface 22a of the dot matrix LCD 22 as seen from the front side in the Z direction (the side of the eye E to be examined), and reference numeral XIXB is an enlarged view of the area surrounded by the dotted circle D2 on the display surface 22a.

[0115] As shown in Fig. 19, the LCD control unit 40 of the fourth embodiment corresponds to the third display control unit of the present invention. This LCD control unit 40 performs anti-aliasing processing (also called smoothing processing) on the ring pattern LP displayed on the display surface 22a of the dot-matrix LCD 22, and places, for example, intermediate-color (intermediate gradation) dots at the boundaries of the ring pattern LP. This reduces (makes less noticeable) the jaggedness of the ring pattern LP, thereby pseudo-enhancing the resolution of the ring pattern LP displayed on the display surface 22a, i.e., the ring pattern light L1 projected from the dot-matrix LCD 22 onto the cornea Ec. For example, if the resolution of the ring pattern LP is reduced from 0.18 mm to 0.045 mm, which is one-fourth of that, the required accuracy of the corneal radius of curvature (keratoconductive value) specified by the ISO is met.

[0116] As described above, in the fourth embodiment, by applying anti-aliasing processing to the ring pattern LP displayed on the dot matrix LCD 22, it is possible to ensure the measurement accuracy of the corneal curvature radius of the subject's eye E even when a low-resolution dot matrix LCD 22 is used.

[0117] In the second embodiment, when the placido ring LPM is displayed on the display surface 22a of the dot matrix LCD 22, anti-aliasing processing may be performed on the placido ring LPM in the same manner as in the fourth embodiment.

[0118] [Fifth embodiment] Fig. 20 is a front view of the display surface 22a of the dot-matrix LCD 22 of the fifth embodiment as seen from the front side in the Z direction (the side of the eye E to be examined). Fig. 21 illustrates an example of a grating pattern light L3 projected onto the cornea Ec from the dot-matrix LCD 22 of the fifth embodiment. In each of the above embodiments, the dot-matrix LCD 22 projects a ring pattern light L1 or a placido ring light L1M onto the cornea Ec. However, as described in the fourth embodiment, the occurrence of jaggies in the ring pattern light L1 may reduce the detection accuracy of the ring image from the anterior-segment image D (such as due to fluctuations in the center of gravity of the ring image). Therefore, the corneal measurement device 10 of the fifth embodiment is capable of projecting a pattern light having a different shape from that of each of the above embodiments onto the cornea Ec from the dot-matrix LCD 22.

[0119] The corneal measurement device 10 of the fifth embodiment has basically the same configuration as the corneal measurement device 10 of each of the above embodiments, except for some differences in the functions of the LCD control unit 40. Therefore, parts that are the same in function or configuration as those of each of the above embodiments are given the same reference numerals and their description will be omitted.

[0120] As shown in Fig. 20, the LCD control unit 40 of the corneal measurement device 10 of the fifth embodiment controls the dot matrix LCD 22 to display a grid pattern GP, which is a grid-like pattern, in response to an operation to start measurement of the corneal radius of curvature or the corneal shape performed on the operation unit 16. As a result, grid pattern light L3 corresponding to the grid pattern GP is projected from the dot matrix LCD 22 onto the cornea Ec, as shown in Fig. 21. Then, return light L2 from the cornea Ec onto which the grid pattern light L3 is projected enters the imaging optical system 26 through the objective lens 24, and the imaging optical system 26 captures the return light L2 and outputs an anterior-segment image D.

[0121] The corneal radius of curvature calculation unit 36 or the corneal shape calculation unit 42 of the fifth embodiment detects a pattern image corresponding to the grating pattern light L3 from the anterior segment image D based on the anterior segment image D output from the imaging optical system 26, and calculates the corneal radius of curvature or the corneal shape of the subject's eye E using a known method based on the detection result of this pattern image.

[0122] As described above, in the fifth embodiment, by making it possible to project grid pattern light L3 onto the cornea Ec from the dot matrix LCD 22, it is possible to measure the corneal radius of curvature or corneal shape of the test eye E with higher accuracy than when ring pattern light L1 is projected onto the cornea Ec.

[0123] The shape of the pattern light projected from the dot matrix LCD 22 onto the cornea Ec is not limited to the examples shown in the above embodiments and can be modified as appropriate as long as it is possible to measure the corneal radius of curvature or corneal shape of the subject's eye E.

[0124] [Sixth embodiment] Fig. 22 is an explanatory diagram for explaining a problem when the dot matrix LCD 22 is used as an illumination light source for the anterior segment of the subject's eye E. Fig. 23 is a front view of the dot matrix LCD 22 in Fig. 22 as seen from the front side in the Z direction (the subject's eye E side).

[0125] As shown in Figures 22 and 23, it is possible to use a dot matrix LCD 22 as an illumination light source to illuminate the anterior segment of the subject's eye E in the corneal measurement device 10, but in this case, there is a risk that the amount of light provided by the ring pattern light L1 (corneal curvature measurement device) or the Placido ring light L1M (corneal shape measurement device) will be insufficient.

[0126] Therefore, in the corneal measurement device 10 of the sixth embodiment, display control is performed on the display surface 22a so that the dot matrix LCD 22 also serves as an illumination light source. The corneal measurement device 10 of the sixth embodiment has basically the same configuration as the corneal measurement devices 10 of the above-mentioned embodiments, except for a partial difference in the function of the LCD control unit 40. Therefore, parts that are the same in function or configuration as those of the above-mentioned embodiments are given the same reference numerals, and their description will be omitted.

[0127] Fig. 24 is an explanatory diagram for explaining illumination of the anterior segment of the eye E by the dot matrix LCD 22 of the corneal measurement device 10 of the sixth embodiment. Fig. 25 is a front view of the dot matrix LCD 22 in Fig. 24 as seen from the front side in the Z direction (the side of the eye E).

[0128] 24 and 25 , when an operation to start illuminating the anterior segment of the eye E is performed on the operation unit 16, the LCD control unit 40 of the sixth embodiment controls the dot-matrix LCD 22 to display an illumination pattern IP for illuminating the anterior segment of the eye E on the display surface 22a. This illumination pattern IP is displayed on the display surface 22a by the LCD control unit 40 so that its display area is larger than that of the ring pattern LP (corneal curvature measurement device) or the Placido ring LPM (corneal topography measurement device). As a result, an illumination pattern light L4 corresponding to the illumination pattern IP is projected from the dot-matrix LCD 22 onto the anterior segment (cornea Ec) of the eye E. Since the light intensity of this illumination pattern light L4 is greater than that of the ring pattern light L1 or the Placido ring light L1M, the anterior segment of the eye E can be illuminated with the illumination pattern light L4.

[0129] The shape of the illumination pattern IP is not particularly limited as long as the illumination pattern IP has a larger display area on the display surface 22a than the ring pattern LP or the Placido ring LPM. For example, the illumination pattern IP may be enlarged to cover the entire surface (including substantially the entire surface) of the display surface 22a, and the illumination pattern light L4 may be projected onto the anterior segment of the subject's eye E from the entire surface of the display surface 22a.

[0130] As described above, in the sixth embodiment, the illumination pattern light L4 can be projected from the dot matrix LCD 22 onto the anterior segment of the subject's eye E, so that the dot matrix LCD 22 can also be used as an illumination light source. As a result, the number of parts of the corneal measurement device 10 can be reduced, thereby achieving cost reduction.

[0131] [Seventh embodiment] Fig. 26 is a front view of the dot matrix LCD 22 as seen from the front side in the Z direction (the side of the eye E to be examined). Fig. 27 is an explanatory diagram showing the ring pattern light L1 projected from the dot matrix LCD 22 onto the cornea Ec, and is a diagram for explaining the problem when the dot matrix LCD 22 is used as an alignment light source for aligning the measurement head 12 with the eye E to be examined.

[0132] In each of the above embodiments, alignment is performed by the alignment control unit 34 by projecting alignment light from the alignment optical system 27 onto the cornea Ec, but in the corneal measurement device 10 of the seventh embodiment, alignment is performed using a dot matrix LCD 22 instead of the alignment optical system 27.

[0133] 26 and 27, if the ring light pattern L1 projected from the dot matrix LCD 22 onto the cornea Ec falls on the iris or the edge of the iris of the subject's eye E, it becomes difficult to detect a ring image corresponding to this ring light pattern L1 from the anterior eye image D, which may result in a decrease in alignment accuracy. Therefore, in the corneal measurement device 10 of the seventh embodiment, the dot matrix LCD 22 is controlled to adjust the shape of the ring light pattern L1 projected onto the cornea Ec so that the ring image corresponding to the ring light pattern L1 can be easily detected from the anterior eye image D.

[0134] The corneal measurement device 10 of the seventh embodiment has basically the same configuration as the corneal measurement device 10 of each of the above-mentioned embodiments, except for some differences in the functions of the LCD control unit 40 and the alignment control unit 34. Therefore, parts that are the same in function or configuration as those of each of the above-mentioned embodiments are given the same reference numerals and their description will be omitted.

[0135] Fig. 28 is a front view of the dot matrix LCD 22 as seen from the front side in the Z direction (the side of the eye E to be examined), showing a state in which a ring pattern LA for alignment is displayed on the display surface 22a. Fig. 29 is an explanatory diagram showing alignment light L5 projected from the dot matrix LCD 22 onto the cornea Ec.

[0136] As shown in Figures 28 and 29, the LCD control unit 40 of the seventh embodiment controls the dot matrix LCD 22 during alignment to display a ring pattern LA for XY alignment on the display surface 22a, and projects alignment light L5 corresponding to this ring pattern LA from the dot matrix LCD 22 onto the cornea Ec.

[0137] At this time, the ring diameter of the ring pattern LA displayed on the display surface 22a is adjusted to a size such that the alignment light L5 emitted from the dot matrix LCD 22 is projected onto the inside of the iris of the subject's eye E, i.e., onto the pupil. For example, in the seventh embodiment, the ring diameter of the ring pattern LA is formed to be smaller than the ring diameter of the ring pattern LP for measuring the corneal radius of curvature. This prevents the alignment light L5 from impinging on the iris or iris edge of the subject's eye E. Then, the return light L2 from the cornea Ec onto which the alignment light L5 is projected enters the imaging optical system 26 through the objective lens 24, and the imaging optical system 26 captures the return light L2 and outputs an anterior eye image D.

[0138] The alignment control unit 34 of the seventh embodiment detects the alignment of the measurement head 12 in the XY directions relative to the test eye E based on the anterior eye image D input from the imaging optical system 26, and drives the drive mechanism 14 based on the alignment detection results to perform alignment in the XY directions.

[0139] Although not shown, an alignment pattern for Z alignment may be displayed on the display surface 22a of the dot matrix LCD 22, and Z alignment light corresponding to this alignment pattern may be projected onto the cornea Ec. In this case as well, the imaging optical system 26 captures the returned light L2 and outputs the anterior eye image D, and the alignment control unit 34 detects the alignment of the measurement head 12 in the Z direction with respect to the subject's eye E based on the anterior eye image D input from the imaging optical system 26, and drives the drive mechanism 14 based on the alignment detection result to perform alignment in the Z direction.

[0140] As described above, in the seventh embodiment, by making it possible to project alignment light L5 from the dot matrix LCD 22 onto the cornea Ec, the dot matrix LCD 22 can also be used as the alignment optical system 27. As a result, the alignment optical system 27 can be omitted from the corneal measurement device 10, which reduces the number of components in the corneal measurement device 10 and thereby reduces costs. Furthermore, since the shape and size of the alignment light L5 can be adjusted as desired, the robustness of alignment detection can be improved.

[0141] [Eighth embodiment] FIG. 30 is a front view of the objective lens 24 and the dot-matrix LCD 22 of the multifunction device 9 of the eighth embodiment. In each of the above embodiments, the corneal measurement device 10 is provided with the dot-matrix LCD 22, but in the eighth embodiment, as shown in FIG. 30, the multifunction device 9 is provided with the dot-matrix LCD 22. The multifunction device 9 of the eighth embodiment combines the corneal measurement device 10 of each of the above embodiments with an optical coherence tomography (OCT) that obtains a tomographic image of the subject's eye E using optical coherence tomography (OCT). The multifunction device 9 has basically the same configuration as the corneal measurement device 10 of each of the above embodiments, except that the measurement head 12 includes a well-known optical system for OCT measurement. Therefore, components that are identical in function or configuration to those of the above embodiments are designated by the same reference numerals, and their description will be omitted.

[0142] When OCT measurement (tomography) of the subject's eye E is performed using the multifunction device 9, fixation is performed to examine a desired portion of the subject's eye E. This fixation is achieved by emitting fixation light toward the subject's eye E and having the subject's eye E gaze at this fixation light. As such fixation, in addition to internal fixation in which fixation light is projected onto the subject's eye E through the objective lens 24, peripheral fixation and external fixation are also known (see, for example, JP 2020-138002 A).

[0143] Peripheral fixation is a fixation method in which the subject's eye E is rotated significantly in a desired direction by selectively illuminating multiple fixation holes (fixation lights) arranged around the objective lens 24. External fixation is performed using an external fixation light, and by adjusting the position of the light source of the external fixation light, the subject's eye can be rotated in any direction, or rotated more significantly than in internal fixation, or the direction of the subject's eye E can be adjusted by guiding the line of sight of the subject's eye E or fellow eye when internal fixation is not possible. In the multifunction peripheral 9 of the eighth embodiment, peripheral fixation is performed using the dot matrix LCD 22.

[0144] When peripheral fixation of the subject's eye E is performed, the LCD control unit 40 of the eighth embodiment controls the dot matrix LCD 22 in accordance with a selection operation input to the operation unit 16 to selectively light up eight (or a number other than eight) fixation areas 50 that are arranged so as to surround the objective lens 24 within the display surface 22a and correspond to conventional fixation holes. As a result, fixation light is projected onto the subject's eye E from the lit fixation areas 50, and peripheral fixation is performed.

[0145] Furthermore, if the display area of the display surface 22a of the dot matrix LCD 22 is large, the fixation area 50 can be lit at any position within the display surface 22a (a position specified by the operation unit 16), and external fixation can be performed by projecting this fixation area 50 onto the subject's eye E.

[0146] It should be noted that the ring pattern light L1 projected onto the cornea Ec from the dot matrix LCD when measuring the corneal radius of curvature or the corneal shape is infrared light, but the fixation light used for fixating the subject's eye E is visible light. For this reason, in the eighth embodiment, it is preferable to use a dot matrix LCD 22 that can switch between emitting infrared light and emitting visible light, for example, a dot matrix LCD 22 that has two types of LEDs, an infrared LED and a white LED.

[0147] As described above, in the eighth embodiment, the dot matrix LCD 22 can project fixation light onto the subject's eye E, so the dot matrix LCD 22 can also be used as a fixation light source (fixation hole, external fixation light). As a result, the fixation light source can be omitted from the multifunction device 9, reducing the number of components in the multifunction device 9 and achieving cost reduction. Furthermore, by using the dot matrix LCD 22 as a fixation light source, the light intensity, color, size, position, etc. of the fixation light can be changed as desired.

[0148] In the above eighth embodiment, the multifunction device 9 is described as an example in which an optical coherence tomography device is combined with the corneal measurement device 10, but the present invention can also be applied to a multifunction device 9 in which the corneal measurement device 10 is combined with various ophthalmic devices that fixate the subject's eye E, such as a fundus camera.

[0149] [others] In each of the above embodiments, various types of light are projected onto the subject's eye E from the dot matrix LCD 22, but various types of light may also be projected onto the subject's eye E using a known dot matrix display such as an organic EL (Electro Luminescence) display or a micro LED display that integrates only LEDs without using liquid crystal.

[0150] In the above embodiments, a keratometer, a corneal topographer, or a combination machine of a keratometer or the like has been described as an example of the corneal measurement device 10. However, the present invention can also be applied to, for example, a corneal endothelial cell photographing device (specular microscope) or a combination machine thereof that irradiates a slit light onto the cornea Ec and receives reflected light from the corneal endothelial cells of the cornea Ec to photograph the corneal endothelial cells. [Explanation of symbols]

[0151] 9 Multifunction device 10 Keratometry device 12 Measuring head 14 Drive mechanism 16 Control section 20 Lens holder 22 dot matrix LCD 22a Display surface 22b Through hole 23 pixels 24 objective lenses 26 Imaging optical system 27 Alignment optical system 28 monitors 30 Control device 32 Imaging control unit 34 Alignment control unit 36 Corneal curvature radius calculation section 38 Monitor control unit 40 LCD control unit 40a Incident angle calculation section 40b Height position calculation unit 42 Corneal shape calculation section 44 Movement control unit 50 fixation area C. Dotted circle D Anterior segment image D1,D2 dotted circle E. Examined eye Ec cornea GP Grid Pattern H Height position L1 Ring Pattern Light L1M Placido Ring Light L2 Return light L3 Grid pattern light L4 Lighting pattern light L5 Alignment Light LA Ring Pattern LC dot matrix LP Ring Pattern LPM Placido Ring O1 optical axis

Claims

1. a dot matrix display that projects pattern light onto at least the cornea of the subject's eye and is capable of arbitrarily changing the shape of the pattern light; an imaging optical system that captures an image of return light from the subject's eye onto which the pattern light is projected by the display, and outputs an image of an anterior segment of the subject's eye; a first display control unit that controls the display based on the anterior eye image output from the imaging optical system so that a projection position of the pattern light is set to a predetermined target position of the cornea; A corneal measurement device comprising:

2. 2. The corneal measurement device according to claim 1, wherein the display is a liquid crystal display.

3. A corneal curvature radius calculation unit is provided which calculates a corneal curvature radius of the subject's eye based on the anterior eye image output from the imaging optical system, 3. The corneal measurement device according to claim 1, wherein the first display control unit controls the display based on the calculation result of the corneal curvature radius calculation unit to correct the projection position of the pattern light on the cornea to the target position.

4. A corneal measurement device as described in Claim 3, wherein the corneal curvature radius calculation unit recalculates the corneal curvature radius based on the anterior eye image output from the imaging optical system when the projection position of the pattern light is corrected by the first display control unit.

5. A dot matrix display that projects pattern light onto at least the cornea of the subject's eye and is capable of arbitrarily changing the shape of the pattern light; an imaging optical system that captures an image of return light from the subject's eye onto which the pattern light is projected by the display, and outputs an image of an anterior segment of the subject's eye; Equipped with the pattern light is a ring pattern light, a corneal curvature radius calculation unit that calculates a corneal curvature radius of the subject's eye based on the anterior eye image output from the imaging optical system; a first display control unit that controls the display based on a calculation result of the corneal curvature radius calculation unit to correct a projection position of the ring pattern light on the cornea to a predetermined target position; Equipped with a corneal radius of curvature calculation unit that recalculates the corneal radius of curvature based on the anterior segment image output from the imaging optical system when the projection position of the ring pattern light is corrected by the first display control unit.

6. 6. The corneal measurement device according to claim 4, wherein the first display control unit calculates an incident angle of the pattern light with respect to the cornea that allows the pattern light to be incident on the target position based on the calculation result of the corneal radius of curvature calculation unit and the target position, and corrects the projection position based on the calculation result of the incident angle.

7. The corneal measurement device according to claim 4 , wherein correction of the projection position by the first display control unit and recalculation of the corneal radius of curvature by the corneal radius of curvature calculation unit are repeatedly performed.

8. the pattern light is a ring pattern light, a second display control unit that controls the display to change a ring diameter of the ring pattern light projected onto the cornea a plurality of times; a first imaging control unit that, when the ring diameter is changed by the second display control unit, causes the imaging optical system to capture an image of the returned light for each of the ring diameters; a corneal shape calculation unit that calculates a corneal shape of the subject's eye based on the anterior eye image captured by the imaging optical system for each ring diameter; The corneal measurement device according to claim 1 , further comprising:

9. a measurement head including the display and the imaging optical system; a drive mechanism that moves the measurement head relative to the subject's eye along the optical axis of the imaging optical system; a second imaging control unit that causes the imaging optical system to capture images of the return light at a plurality of imaging positions that are different from each other along the optical axis when the measurement head is moved relative to the eye to be examined in the optical axis direction by the drive mechanism; and a corneal shape calculation unit that calculates a corneal shape of the subject's eye based on the anterior eye image captured by the imaging optical system at each imaging position; The corneal measurement device according to claim 1 , further comprising:

10. the display has a display surface that displays a ring pattern; a third display control unit that performs anti-aliasing processing on the ring pattern displayed on the display surface; The corneal measurement device according to claim 1 , wherein the display projects, as the pattern light, a ring pattern light corresponding to the ring pattern that has been subjected to the anti-aliasing process onto the cornea.

11. the display projects the grid-shaped pattern light onto the cornea; 5. The corneal measurement device according to claim 1, further comprising a corneal shape calculation unit that calculates a corneal shape of the subject's eye based on the anterior eye image output from the imaging optical system.

12. 12. The corneal measurement device according to claim 1, wherein the display displays an illumination pattern for illuminating an anterior segment of the subject's eye, the illumination pattern having an area larger than that of a ring pattern used to measure the corneal radius of curvature or the corneal shape of the subject's eye, and projects the pattern light corresponding to the illumination pattern onto the anterior segment.

13. a measurement head including the display and the imaging optical system; a drive mechanism that moves the measurement head relative to the eye to be examined; Equipped with the display is capable of projecting alignment light used for aligning the measurement head with respect to the subject's eye onto the cornea; 13. The corneal measurement device according to claim 1, further comprising an alignment control unit that, when the alignment light is projected from the display onto the cornea, drives the drive mechanism based on the anterior eye image output from the imaging optical system to align the measurement head with the subject's eye.

14. The corneal measurement device according to any one of claims 1 to 13, wherein the display is capable of projecting fixation light onto the subject's eye to cause the subject's eye to fixate the eye.

15. an objective lens that transmits the return light from the subject's eye and outputs the return light to the imaging optical system; a cylindrical lens holding portion that houses the objective lens; a through hole formed in the display and through which the lens holding portion passes; Equipped with The corneal measurement device according to any one of claims 1 to 14, wherein the display is fitted and fixed to the outside of the lens holding portion.

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