Contact-type tonometer and method for operating same

Abstract

This contact-type tonometer comprises: a contact portion having a contact surface that comes into contact with a cornea of an eye; one or a plurality of contact sensors that are provided on at least a portion of the periphery of the contact surface and detect contact with the cornea; a pressure sensor that detects pressure applied from the eye to the contact surface; a determination unit that determines, on the basis of detection results of the contact sensors, whether or not an amount by which the contact surface pushes the cornea is appropriate; and an intraocular pressure value calculation unit that calculates an intraocular pressure value on the basis of the pressure detected by the pressure sensor when the determination unit determines that the amount is appropriate.

Description

Contact tonometer and method of operating the same

[0001] The present disclosure relates to a contact tonometer for measuring an intraocular pressure value of an eye and a method of operating the same.

[0002] A contact tonometer (also referred to as an applanation tonometer or Goldmann applanation tonometer) that measures an intraocular pressure value (true value) of an eye to be examined by bringing a probe into contact with the cornea of the examinee's eye (human eye) is known (see Patent Document 1: Japanese Unexamined Patent Publication No. 2004-073601). In intraocular pressure measurement using this contact tonometer, an examiner (measurement operator) first instills an anesthetic and fluorescein into the examinee's eye, then brings the probe into contact with the cornea of the examinee's eye. Next, the examiner irradiates blue light onto the examinee's eye from a microscope of the contact tonometer to cause the tear film on the cornea to emit light, and observes upper and lower divided semicircular tear rings through the microscope. After the examiner performs a pressure adjustment operation of adjusting the pressure applied to the probe so that the upper and lower tear rings overlap, an arithmetic device calculates the intraocular pressure value of the examinee's eye using the pressure obtained after the pressure adjustment operation and other parameters.

[0003] Further, Patent Document 2 (Japanese Unexamined Patent Publication No. 2004-041372) discloses a contact tonometer that allows a subject to measure their own intraocular pressure value. In intraocular pressure measurement using this contact tonometer, the probe is brought into contact from above the eyelid of the examinee's eye to press the cornea through the eyelid, and the intraocular pressure value of the examinee's eye is calculated from the pressure value of a pressure sensor provided on the distal end surface of the probe.

[0004] In the intraocular pressure measurement performed by the contact tonometer described in Patent Document 1, the examiner needs to perform a pressure adjustment operation to adjust the pressure applied to the probe so that the upper and lower tear rings overlap each other, so variations occur in this pressure adjustment operation depending on the skill of the examiner. In addition, the corneal tear condition (such as tear volume) of the subject also fluctuates. Therefore, in the intraocular pressure measurement performed by the contact tonometer described in Patent Document 1, due to variations in the pressure adjustment operation caused by the examiner's skill and fluctuations in the subject's corneal tear condition, the upper and lower tear rings, which serve as measurement indicators, fail to satisfy the requirements of appropriate pressurization amount and appropriate size, resulting in significant fluctuation in the intraocular pressure value. This problem also occurs when a manufacturer of contact tonometers measures the intraocular pressure of a model eye for calibrating a contact tonometer.

[0005] Furthermore, while the contact-type tonometer described in Patent Document 2 allows the subject to measure their own intraocular pressure, it does not directly press the cornea with a probe, resulting in a problem of inferior accuracy in measuring intraocular pressure.

[0006] This disclosure is made in view of these circumstances and aims to provide a contact-type tonometer and a method for operating the same that can stably and accurately measure intraocular pressure.

[0007] A contact tonometer for achieving the objectives of this disclosure is a contact tonometer for measuring the intraocular pressure of the eye, comprising: a contact portion having a contact surface that contacts the cornea of ​​the eye; one or more contact sensors provided around at least a part of the periphery of the contact surface for detecting contact with the cornea; a pressure sensor for detecting pressure applied from the eye to the contact surface; a determination unit for determining whether the amount the contact surface presses against the cornea is appropriate based on the detection results of the contact sensors; and an intraocular pressure calculation unit for calculating the intraocular pressure based on the pressure detected by the pressure sensor when the determination unit determines that it is appropriate.

[0008] The contact-type tonometer and its operating method described herein can perform stably and accurately measure the intraocular pressure of the eye.

[0009] This is a side view of a contact-type tonometer. This is a magnified side view of the tip of the contact prism. This is a magnified front view of the tip of the contact prism in Figure 2, as seen from the side of the eye E being examined. This is a diagram illustrating the method for determining the appropriate amount of indentation using a contact sensor. This is a functional block diagram of the control device. This is a flowchart showing the flow of the intraocular pressure measurement process of the eye being examined using a contact-type tonometer. This is a diagram showing a modified example of the detection sensor.

[0010] <Overall Configuration of Contact Tonometer 10> Figure 1 is a side view of the contact tonometer 10 of this disclosure. Of the mutually orthogonal XYZ directions in the figure, the X direction is the left-right direction with respect to the subject (the interpupillary width direction of the subject's eye E), the Y direction is the up-down direction, and the Z direction is the working distance direction, which is parallel to the forward direction towards the subject and the backward direction away from the subject.

[0011] As shown in Figure 1, the contact tonometer 10 measures the intraocular pressure of the eye E being examined. This contact tonometer 10 comprises a base 12, an arm 14, an alignment stage 16, a measuring head 18, an operating unit 20, a control device 22, and a display device 24.

[0012] An arm 14 parallel to the Y direction is provided on the upper surface of the base 12. The lower end of the arm 14 in the Y direction is held by an alignment stage 16 provided on the base 12. A measuring head 18 is provided at the upper end of the arm 14 in the Y direction.

[0013] The alignment stage 16 corresponds to the head movement mechanism of this disclosure and, although not shown in the figures, comprises a stage that holds the arm 14 and an electric actuator (motor drive mechanism) that moves the stage. The alignment stage 16 is driven by the control device 22 in response to manual movement operations input by the examiner to the operation unit 20, thereby moving the arm 14 along at least the Z direction among the XYZ directions. This makes it possible to move the measuring head 18 at least in the Z direction. Note that a head movement mechanism other than the alignment stage 16 may be used as long as it is possible to move the arm 14 and the measuring head 18. Furthermore, this head movement mechanism is not limited to an electrically driven one, and may be a manual movement mechanism that can move the arm 14 and the measuring head 18 in response to push and pull operations by the examiner.

[0014] The measuring head 18 contacts the cornea Ec during intraocular pressure measurement of the eye E under examination, pressing down on the cornea Ec and measuring the pressure applied to the measuring head 18 from the eye E under examination. The configuration of the measuring head 18 will be described later.

[0015] The control unit 20 accepts manual movement of the measuring head 18, ON / OFF operation of the contact tonometer 10, and various setting operations for the contact tonometer 10.

[0016] The control device 22 centrally controls the operation of the contact tonometer 10 in response to operational input to the operation unit 20. The control device 22 drives the alignment stage 16 to move the arm 14 and the measuring head 18 in response to manual movement operations of the measuring head 18 input to the operation unit 20. The control device 22 also performs a pressure amount appropriateness determination (hereinafter simply abbreviated as "pressure amount appropriateness determination") to determine whether the amount the measuring head 18 presses into the cornea Ec is appropriate. Furthermore, if the pressure amount appropriateness determination is deemed appropriate, the control device 22 obtains the pressure measurement result from the measuring head 18 and calculates the intraocular pressure value of the eye E being examined based on this measurement result.

[0017] In this embodiment, the control device 22 is provided separately from the base 12 and the measuring head 18, but the control device 22 may also be provided within the base 12 or within the measuring head 18.

[0018] The display device 24 displays the result of the control device 22's determination of the appropriate amount of indentation, and the intraocular pressure value of the eye E being examined, which is calculated by the control device 22.

[0019] <Configuration of the measuring head 18> The measuring head 18 comprises a head body 30, a contact prism 32, a contact sensor 34, and a pressure sensor 36.

[0020] The head body 30 is fixed to the upper end of the arm 14 in the Y direction. The head body 30 holds the contact prism 32, more specifically its rear end (base end), so that it can move in the Z direction. A pressure sensor 36 is also provided inside the head body 30.

[0021] The contact prism 32 corresponds to the contact portion of this disclosure and is formed in a cylindrical shape parallel to the Z direction. Hereinafter, the front end of the contact prism 32 in the Z direction (towards the eye E, corresponding to one direction of this disclosure) will be referred to as the "tip of the contact prism 32," and the rear end of the contact prism 32 in the Z direction (corresponding to the other direction of this disclosure) will be referred to as the "rear end of the contact prism 32."

[0022] Figure 2 is a magnified side view of the tip of the contact prism 32. Figure 3 is a magnified front view of the tip of the contact prism 32 in Figure 2, as seen from the eye E side of the eye being examined.

[0023] As shown in Figures 2 and 3, the tip of the contact prism 32 is provided with a contact surface 32a that contacts the cornea Ec during intraocular pressure measurement and pushes the cornea Ec in. The contact surface 32a is planar and parallel to the XY plane and has a circular outer shape. In this embodiment, the contact prism 32 is formed in a cylindrical shape and the outer shape of the contact surface 32a is circular, but these shapes are not particularly limited and can be changed to any shape. In addition, contact parts other than the contact prism 32 may be used as long as it is possible to push the cornea Ec in, and the material of the contact part is also not particularly limited.

[0024] The diameter φ of the contact surface 32a is φ = 3.06 mm, which is commonly used for contact-type intraocular pressure measurement. The state in which the corneal Ec is pressed down using only the entire area of ​​this contact surface 32a and flattened (hereinafter referred to as the optimal flattening state, see reference numeral 4B in Figure 4) is the state in which the control device 22 determines the appropriate amount of pressure to be appropriate, and is the optimal state for intraocular pressure measurement.

[0025] The contact sensor 34 is provided at the tip of the contact prism 32 and detects contact with the cornea Ec. When viewed from the front side in the Z direction, the contact sensor 34 is formed in an annular shape (it can be an annular shape other than an annular shape) that surrounds and circumscribes the contact surface 32a. In addition, the contact sensor 34 has an annular detection surface 34a that is coplanar with the contact surface 32a when viewed from the X or Y direction. The shapes of the contact sensor 34 and the detection surface 34a can be appropriately changed according to the shapes of the contact prism 32 and the contact surface 32a.

[0026] The contact sensor 34 outputs a detection signal (electrical signal) when the cornea Ec comes into contact with its detection surface 34a. Therefore, it is possible to determine whether or not the detection surface 34a is in contact with the cornea Ec based on the presence or absence of a detection signal output from the contact sensor 34. As a method for detecting the cornea Ec using such a contact sensor 34, known detection methods such as resistive, capacitive, and ultrasonic methods can be employed. In addition, known proximity sensors, distance sensors, or pressure sensors can be used as the contact sensor 34 as long as they can substantially detect contact with the cornea Ec.

[0027] In this embodiment, the contact sensor 34 enables the control device 22 to determine the appropriate amount of indentation, that is, it makes it possible to determine whether or not the corneal Ec has reached the optimal applanation state.

[0028] Figure 4 is a diagram illustrating a method for determining the appropriate amount of indentation using a contact sensor 34. As shown by reference numeral 4A in Figure 4, first, the alignment stage 16 performs an approach process to move the measuring head 18 (contact surface 32a) forward in the Z direction. This approach process continues until the measuring head 18 reaches a position where the cornea Ec contacts the detection surface 34a, and a detection signal is output from the contact sensor 34.

[0029] When a detection signal is output from the contact sensor 34, the alignment stage 16 performs a retraction process to move the measuring head 18 backward in the Z direction, as shown by reference numeral 4B in Figure 4. This retraction process continues until the measuring head 18 reaches a position where the detection surface 34a is separated from the cornea Ec, and the output of the detection signal from the contact sensor 34 stops. Since the detection surface 34a is provided in an annular shape around the contact surface 32a, the point at which the output of the detection signal from the contact sensor 34 stops corresponds to the state in which the detection surface 34a is separated from the cornea Ec and the cornea Ec is flattened only by the entire area of ​​the contact surface 32a, i.e., the optimal flattening state. Therefore, it is possible to determine the appropriateness of the indentation amount (determining whether or not the cornea Ec has reached the optimal flattening state) based on the presence or absence of a detection signal output from the contact sensor 34 during the retraction process.

[0030] Furthermore, if a detection signal is output from the contact sensor 34 during the approach process, this fact will be displayed on the display device 24. This allows the examiner to refer to the display on the display device 24 to stop the approach process and start the retraction process. In addition, the examiner may be notified of the output of a detection signal from the contact sensor 34 by a method other than the display device 24 (e.g., indicator light, speaker).

[0031] Returning to Figure 1, the pressure sensor 36 is connected, for example, to the rear end of the contact prism 32. When the cornea Ec is pushed forward in the Z direction by the contact prism 32, the pressure sensor 36 detects the pressure applied from the cornea Ec (the eye being examined E) to the contact prism 32 and outputs the detection result to the control device 22.

[0032] <Functions of Control Device 22> Figure 5 is a functional block diagram of the control device 22. As shown in Figure 5, the control device 22 includes an arithmetic circuit composed of various processors and memory. The various processors include CPUs (Central Processing Units), GPUs (Graphics Processing Units), ASICs (Application Specific Integrated Circuits), and programmable logic devices [for example, SPLDs (Simple Programmable Logic Devices), CPLDs (Complex Programmable Logic Devices), and FPGAs (Field Programmable Gate Arrays)]. The various functions of the control device 22 may be realized by a single processor, or by multiple processors of the same or different types.

[0033] The control device 22 functions as a movement control unit 40, a determination unit 42, and an intraocular pressure value calculation unit 44 by executing a control program stored in a memory unit (not shown).

[0034] The movement control unit 40 drives the alignment stage 16 to move the arm 14 and the measurement head 18 in response to the manual movement operation of the measurement head 18 input by the examiner to the operation unit 20. This makes it possible to perform XY alignment of the measurement head 18 with respect to the eye E under examination. Furthermore, after the completion of this XY alignment, it is possible to perform approach and retraction processes for the measurement head 18.

[0035] The determination unit 42 performs an appropriate determination of the indentation amount (determining whether or not the corneal Ec has reached the optimal flattening state) based on whether or not a detection signal is output from the contact sensor 34. For example, the determination unit 42 is activated when a detection signal is output from the contact sensor 34 due to the detection surface 34a coming into contact with the corneal Ec as a result of the measuring head 18 approaching process (see reference numeral 4A in Figure 4), or when the retraction process of the measuring head 18 is started thereafter.

[0036] Next, the determination unit 42 determines that, after the retraction process of the measuring head 18 has started, while a detection signal is being output from the contact sensor 34, the amount by which the contact surface 32a presses into the cornea Ec is not appropriate, that is, the cornea Ec is not in the optimal flattened state. Then, when the retraction process of the measuring head 18 continues and the detection surface 34a moves away from the cornea Ec, and the output of the detection signal from the contact sensor 34 stops (see reference numeral 4B in Figure 4), the determination unit 42 determines that the amount by which the contact surface 32a presses into the cornea Ec is appropriate, that is, the cornea Ec is in the optimal flattened state.

[0037] The determination result of the determination unit 42 (whether or not a detection signal is output from the contact sensor 34) is displayed on the display device 24. This allows the examiner to stop the retraction process by referring to the display on the display device 24. Alternatively, the determination result of the determination unit 42 may be communicated to the examiner by a method other than the display device 24 (e.g., indicator light, speaker).

[0038] The intraocular pressure (IOP) calculation unit 44, when the determination unit 42 determines that the corneal Ec is in an optimal applanation state, obtains the pressure detection result from the pressure sensor 36 and calculates the IOP value of the eye under examination E based on this pressure. For example, the IOP calculation unit 44 calculates the IOP value of the eye under examination E using the calculation formula expressed as "pressure × correction coefficient = IOP value". The "correction coefficient" in this calculation formula is determined in advance through clinical evaluation or the like. The IOP calculation unit 44 then outputs the IOP calculation result to the display device 24.

[0039] [Operation of the Contact Tonometer 10] Figure 6 is a flowchart showing the flow of the intraocular pressure measurement process of the eye E to be examined using the contact tonometer 10 configured as described above, relating to the operation method of the contact tonometer of the present disclosure.

[0040] After the subject's face is supported by a face support unit (not shown), the examiner adjusts the height of the subject's face using the face support unit, and then inputs a manual movement operation (XY alignment operation) of the measuring head 18 to the operation unit 20. This causes the movement control unit 40 to drive the alignment stage 16, thereby performing XY alignment of the measuring head 18 with respect to the subject's eye E. Next, the examiner inputs a manual movement operation to the operation unit 20 to move the measuring head 18 forward in the Z direction. In response to this manual movement operation, the movement control unit 40 drives the alignment stage 16 to start the approach process of the contact prism 32 (corresponding to step S1, the approach step and movement step in this disclosure).

[0041] The examiner continues to input manual movement operations to the operation unit 20, i.e., the process of approaching the measuring head 18, until a detection signal is output from the contact sensor 34 (NO in step S2). Then, as shown by reference numeral 4A in Figure 4 described above, when the detection surface 34a comes into contact with the cornea Ec, a detection signal is output from the contact sensor 34 and this fact is displayed on the display device 24 (YES in step S2). At this point, the examiner stops inputting manual movement operations to the operation unit 20 and completes the process of approaching the measuring head 18 (step S3).

[0042] After the approach process of the measuring head 18 is completed, the examiner inputs a manual movement operation to the operation unit 20 to move the measuring head 18 to the rear in the Z direction. Upon receiving this manual movement operation, the movement control unit 40 drives the alignment stage 16 to start the retraction process of the measuring head 18 (corresponding to step S4, the retraction step and movement step in this disclosure). In addition, the determination unit 42 operates in conjunction with the retraction process of the measuring head 18.

[0043] After the retraction process begins, the determination unit 42 determines that the amount the contact surface 32a presses against the cornea Ec is not appropriate and that the cornea Ec is not in the optimal flattened state, until the output of the detection signal from the contact sensor 34 stops, and displays the determination result on the display device 24 (corresponding to the determination step of this disclosure). As a result, the examiner continues to input manual movement operations to the operation unit 20, i.e., the retraction process of the measuring head 18, until the output of the detection signal from the contact sensor 34 stops (NO in step S5).

[0044] Then, as shown at reference numeral 4B in FIG. 4 described above, when the detection surface 34a is separated from the cornea Ec, the output of the detection signal from the contact sensor 34 stops. Accordingly, the determination unit 42 determines that the amount by which the contact surface 32a presses the cornea Ec is appropriate, and that the cornea Ec has reached the optimal applanation state, and causes the display device 24 to display this information (YES in step S5, which corresponds to the determination step of the present disclosure). Then, the examiner stops the manual movement operation on the operation unit 20 and completes the retraction processing of the measuring head 18 (step S6).

[0045] Conventionally (see the above Patent Document 1), after instilling an anesthetic and fluorescein into the eye E to be examined, the examiner observes the upper and lower tear meniscus rings through a microscope and performs an adjustment operation of adjusting the pressure applied to the probe such that the upper and lower tear meniscus rings overlap, thereby deforming the cornea Ec into the optimal applanation state. In contrast, in the present embodiment, appropriate pressing amount determination (determination of whether the cornea Ec has reached the optimal applanation state) can be implemented based on whether a detection signal is output from the contact sensor 34 or not.

[0046] When the determination unit 42 determines that the cornea Ec has reached the optimal applanation state, the intraocular pressure value calculation unit 44 acquires the pressure detection result from the pressure sensor 36 (step S7), and calculates the intraocular pressure value of the eye E to be examined based on this pressure and the above calculation formula (step S8, which corresponds to the intraocular pressure value calculation step of the present disclosure). Then, the intraocular pressure value calculation unit 44 outputs the calculation result of the intraocular pressure value to the display device 24. Accordingly, the measurement result of the intraocular pressure value of the eye E to be examined is displayed on the display device 24 (step S9).

[0047] As described above, in the contact tonometer 10 of the present embodiment, appropriate pressing amount determination can be implemented based on whether a detection signal is output from the contact sensor 34 or not, which prevents variation in pressure adjustment operation caused by the examiner's skill as in conventional techniques, and also prevents being affected by the state of the corneal tear fluid of the eye E to be examined. Therefore, intraocular pressure measurement based on the contact (or pressurization) area of the contact surface 32a with respect to the cornea Ec can be implemented, and variation in the measurement results of the intraocular pressure value of the eye E to be examined is reduced. As a result, in the present embodiment, intraocular pressure measurement of the eye E to be examined can be implemented stably and accurately.

[0048] [Modified Example of Contact Sensor 34] Figure 7 is a diagram showing a modified example of the contact sensor 34. In the above embodiment, one contact sensor 34 is provided in an annular shape around the contact surface 32a. However, as shown in FIG. 7, for example, a plurality of contact sensors 34 may be provided at a plurality of partial locations around the contact surface 32a. Even in this case, based on the presence or absence of output of detection signals from each contact sensor 34, the appropriate push-in amount determination can be performed in the same manner as the above embodiment, so the same effects as the above embodiment can be obtained.

[0049] [Others] In the above embodiment, it is determined that the amount by which the contact surface 32a pushes the cornea Ec becomes appropriate (the cornea Ec enters an appropriate applanation state) at the timing when the output of the detection signal from the contact sensor 34 stops during the retraction process of the measurement head 18. However, the present disclosure is not limited to this. For example, the determination may be made that the amount by which the contact surface 32a pushes the cornea Ec becomes appropriate (the cornea Ec enters an appropriate applanation state) at the timing when the output of the detection signal from the contact sensor 34 starts during the approach process of the measurement head 18, that is, at the timing when the detection surface 34a contacts the cornea Ec.

[0050] In the above embodiment, the examiner manually operates to drive the alignment stage 16 to execute the XY alignment, approach process and retraction process of the measurement head 18. However, the control device 22 may automatically drive the alignment stage 16 to execute the XY alignment, approach process and retraction process of the measurement head 18. In this case, all processes from the XY alignment of the measurement head 18 to the measurement and display of the intraocular pressure value of the eye to be examined E can be performed automatically.

[0051] In the above embodiment, the case where the contact tonometer 10 is used to measure the intraocular pressure of a subject (patient) has been described as an example. However, the present disclosure can also be applied to a case where a contact tonometer 10 is used to measure the intraocular pressure of a model eye by a contact tonometer manufacturer or the like.

[0052] Part or all of the above embodiments can also be described as in the following supplementary notes, but is not limited to the following.

[0053] [Addendum 1] A contact-type tonometer for measuring the intraocular pressure of an eye, comprising: a contact portion having a contact surface that contacts the cornea of ​​the eye; one or more contact sensors provided around at least a part of the periphery of the contact surface for detecting contact with the cornea; a pressure sensor for detecting pressure applied from the eye to the contact surface; a determination unit that determines whether the amount the contact surface presses against the cornea is appropriate based on the detection result of the contact sensors; and an intraocular pressure value calculation unit that calculates the intraocular pressure value based on the pressure detected by the pressure sensor when the determination unit determines that it is appropriate.

[0054] [Addendum 2] The contact tonometer according to Addendum 1, comprising a head movement mechanism that moves the measuring head, including the contact portion and the pressure sensor, at least along the working distance direction in response to a manual movement operation or automatically, wherein the head movement mechanism performs an approach process that moves the measuring head toward one direction in the working distance direction until the contact sensor detects contact with the cornea, and a retraction process that, after the approach process, moves the measuring head toward the other direction in the working distance direction until the contact sensor no longer detects contact with the cornea, and the determination unit determines that the tonometer is appropriate when the contact sensor no longer detects contact with the cornea during the retraction process.

[0055] [Appendix 3] A contact-type tonometer according to Appendix 1 or 2, wherein one of the contact sensors is formed in an annular shape surrounding the contact surface.

[0056] [Appendix 4] A contact-type tonometer according to any one of Appendix 1 to 3, comprising a head movement mechanism for moving the measuring head, which includes the contact portion and the pressure sensor, at least along the working distance direction in response to a manual movement operation or automatically, wherein the contact portion is cylindrical in shape parallel to the working distance direction, the outer shape of the contact surface is circular, and the contact sensor is formed in an annular shape.

[0057] [Note 5] The contact-type tonometer according to Note 4, wherein the diameter of the contact surface is 3.06 mm.

[0058] [Appendix 6] An operating method for a contact-type tonometer comprising: a contact portion having a contact surface that contacts the cornea of ​​the eye; one or more contact sensors provided around the periphery of the contact surface and which detect contact with the cornea and output a detection signal; a pressure sensor that detects pressure applied from the eye to the contact surface; and a head movement mechanism that moves a measuring head including the contact portion and the pressure sensor, either manually or automatically, along at least the working distance direction, the operating method comprising: a movement step of moving the measuring head along the working distance direction using the head movement mechanism; a determination step of determining whether the amount the contact surface presses against the cornea is appropriate based on the detection result of the contact sensor; and an intraocular pressure value calculation step of calculating the intraocular pressure value of the eye based on the pressure detected by the pressure sensor when it is determined to be appropriate in the determination step.

[0059] [Addendum 7] The operation method for a contact-type tonometer according to Addendum 6, wherein the movement step comprises: an approach step in which the head movement mechanism moves the measuring head to one direction in the operating distance direction to a position in which the detection signal is output from the contact sensor; and a retraction step in which, after the approach step, the head movement mechanism moves the measuring head to the other direction in the operating distance direction to a position in which the detection signal is no longer output from the contact sensor, and in the determination step, it is determined that the operation is appropriate if the output of the detection signal from the contact sensor is stopped in the retraction step.

[0060] 10... Contact tonometer 12... Base 14... Arm 16... Alignment stage 18... Measurement head 20... Operation unit 22... Control unit 24... Display unit 30... Head body 32... Contact prism 32a... Contact surface 34... Contact sensor 34a... Detection surface 36... Pressure sensor 40... Movement control unit 42... Judgment unit 44... Intraocular pressure value calculation unit E... Eye under examination Ec... Cornea

Claims

1. A contact-type tonometer for measuring the intraocular pressure of an eye, comprising: a contact portion having a contact surface that contacts the cornea of ​​the eye; one or more contact sensors provided around at least a portion of the periphery of the contact surface for detecting contact with the cornea; a pressure sensor for detecting pressure applied from the eye to the contact surface; a determination unit that determines whether the amount the contact surface presses against the cornea is appropriate based on the detection results of the contact sensors; and an intraocular pressure value calculation unit that calculates the intraocular pressure value based on the pressure detected by the pressure sensor when the determination unit determines that it is appropriate.

2. The contact tonometer according to claim 1, comprising a head movement mechanism that moves the measuring head, which includes the contact portion and the pressure sensor, at least along the working distance direction in response to a manual movement operation or automatically, wherein the head movement mechanism performs an approach process that moves the measuring head toward one direction in the working distance direction to a position where the contact sensor detects contact with the cornea, and a retraction process that, after the approach process, moves the measuring head toward the other direction in the working distance direction to a position where the contact sensor no longer detects contact with the cornea, and the determination unit determines that the device is appropriate when the contact sensor no longer detects contact with the cornea during the retraction process.

3. The contact tonometer according to claim 1, wherein one of the contact sensors is formed in an annular shape surrounding the contact surface.

4. The contact tonometer according to claim 2, wherein the contact portion is cylindrical in shape parallel to the operating distance direction, the outer shape of the contact surface is circular, and the contact sensor is formed in an annular shape.

5. The contact tonometer according to claim 4, wherein the diameter of the contact surface is 3.06 mm.

6. An operating method for a contact-type tonometer comprising: a contact portion having a contact surface that contacts the cornea of ​​the eye; one or more contact sensors provided around at least a portion of the periphery of the contact surface, which detect contact with the cornea and output a detection signal; a pressure sensor that detects the pressure applied from the eye to the contact surface; and a head movement mechanism that moves a measuring head including the contact portion and the pressure sensor, either manually or automatically, along at least the working distance direction, the operating method comprising: a movement step of moving the measuring head along the working distance direction using the head movement mechanism; a determination step of determining whether the amount the contact surface presses against the cornea is appropriate based on the detection result of the contact sensor; and an intraocular pressure value calculation step of calculating the intraocular pressure value of the eye based on the pressure detected by the pressure sensor when it is determined to be appropriate in the determination step.

7. The method for operating a contact-type tonometer according to claim 6, wherein the movement step comprises: an approach step in which the head movement mechanism moves the measuring head to one direction in the operating distance direction to a position in which the detection signal is output from the contact sensor; and a retraction step in which, after the approach step, the head movement mechanism moves the measuring head to the other direction in the operating distance direction to a position in which the detection signal is no longer output from the contact sensor, and in the determination step, it is determined that the operation is appropriate if the output of the detection signal from the contact sensor is stopped in the retraction step.

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