Non-contact tonometer and operation method of non-contact tonometer

Abstract

The invention provides a non-contact tonometer and a method for operating the non-contact tonometer, which can achieve both silence and measurement accuracy during intraocular pressure measurement. The present invention is provided with a cylinder (34d), a piston (34f) which is movably provided inside the cylinder (34d), an actuator (electromagnetic element (34g)) which compresses air inside the cylinder (34d) by moving the piston (34f) inside the cylinder (34d) by application of a current, a nozzle (21b) which blows the air compressed by the piston (34f) to a subject eye (E), and a current application control unit (measurement control unit (42)) which applies a current to the actuator and controls the movement of the piston (34f) inside the cylinder (34d). The current application control unit executes a first application process for applying a current to the actuator at a first current value, and switches from the first application process to a second application process for applying a current at a second current value higher than the first current value to the actuator when a predetermined switching condition is satisfied during execution of the first application process.

Description

Technical Field

[0001] The present invention relates to a non-contact tonometer for measuring the intraocular pressure value of an eye to be examined in a non-contact manner and an operating method of the non-contact tonometer. Background Art

[0002] A non-contact tonometer for measuring the intraocular pressure of an eye to be examined without contact is known (for example, see Patent Document 1). In the non-contact tonometer, a blowing mechanism for blowing air from a nozzle toward the cornea of ​​the eye to be examined is provided. Thus, the non-contact tonometer drives the blowing mechanism to blow air from the nozzle toward the cornea of ​​the eye to be examined, thereby deforming the cornea, detecting the deformed state, and thereby measuring the intraocular pressure value of the eye to be examined without contacting the cornea.

[0003] The blowing mechanism of the non-contact tonometer described in Patent Document 1 is composed of a cylinder, a piston, a nozzle, a chamber, and a rotating electromagnetic element. The piston is arranged to be movable inside the cylinder. The nozzle is connected to the chamber and communicates with the interior of the cylinder (pressurized chamber) via the chamber, etc. The rotating electromagnetic element is connected to the piston via a crank mechanism that converts its rotational motion into linear motion. The rotating electromagnetic element rotates by applying an electric current, thereby moving the piston inside the cylinder via the crank mechanism. As a result, the air inside the cylinder compressed by the piston is ejected from the nozzle toward the cornea of ​​the eye to be examined via the chamber, etc.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2022-111333 Summary of the invention

[0007] Problem that the invention aims to solve

[0008] In the non-contact tonometer described in Patent Document 1, a rotating electromagnetic element is driven by electric current and air is blown from a nozzle toward the cornea of ​​the eye to be examined. However, if the sound generated by the blowing mechanism is loud when the rotating electromagnetic element is driven, it may cause discomfort to the examinee. Therefore, it is desirable to silence the sound generated by the blowing mechanism. In order to silence the sound generated by the blowing mechanism, it is necessary to reduce the current value of the current applied to the rotating electromagnetic element.

[0009] However, if the current value of the current applied to the rotating electromagnetic element is reduced, when the rotating electromagnetic element is operated for the first time, although the piston moves as expected, the force applied to the piston via the crank mechanism gradually weakens as the rotating electromagnetic element rotates. Therefore, there is a situation where the pressure of the air in the chamber does not rise, and the pressure of the air blown from the nozzle to the cornea of ​​the eye to be examined is insufficient. In this case, the intraocular pressure value of the eye to be examined cannot be measured with good accuracy.

[0010] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a contact tonometer and a method for operating a non-contact tonometer that can achieve both quietness and measurement accuracy during intraocular pressure measurement.

[0011] Means used to solve problems

[0012] In order to achieve the purpose of the present invention, a non-contact tonometer comprises: a cylinder, a piston, which is movably arranged inside the cylinder, an actuator, which moves the piston inside the cylinder by applying current and compresses the air inside the cylinder with the help of the piston, a nozzle, which is connected to the inside of the cylinder and blows the air compressed by the piston to the eye to be examined, and a current application control unit, which applies current to the actuator; the current application control unit executes a first application process of applying current to the actuator with a first current value, and when a predetermined switching condition is satisfied during the execution of the first application process, switches from the first application process to a second application process of applying a current of a second current value higher than the first current value to the actuator.

[0013] According to this non-contact tonometer, a first current value is applied to the actuator through a first application process to achieve silencing, and the current value applied to the actuator is increased to a second current value when a predetermined switching condition is satisfied, thereby preventing a decrease in the measurement accuracy of the intraocular pressure value of the examined eye.

[0014] In another embodiment of the non-contact tonometer of the present invention, the nozzle is connected to the inside of the cylinder via a chamber connected to the inside of the cylinder, the non-contact tonometer has a pressure sensor for detecting the pressure inside the chamber, and the current application control unit determines whether the switching condition is satisfied based on whether the pressure detected by the pressure sensor reaches a predetermined pressure threshold. Thus, the pressure of the air blown to the eye to be examined is prevented from decreasing.

[0015] In another embodiment of the non-contact tonometer of the present invention, the non-contact tonometer has a detection sensor for detecting the displacement of the actuator, and the current application control unit determines whether the switching condition is satisfied based on whether the displacement detected by the detection sensor reaches a predetermined displacement threshold, thereby preventing the pressure of the air blown to the eye to be examined from decreasing.

[0016] In the non-contact tonometer according to another aspect of the present invention, the current application control unit increases the second current value in a stepwise manner during execution of the second application process.

[0017] In other embodiments of the non-contact tonometer of the present invention, the nozzle is connected to the interior of the cylinder via a chamber connected to the interior of the cylinder, the non-contact tonometer has a pressure sensor for detecting the pressure inside the chamber, and the current application control unit causes the second current value to increase stepwise in response to an increase in pressure detected by the pressure sensor during the execution of the second application process.

[0018] In another embodiment of the non-contact tonometer of the present invention, the non-contact tonometer has a detection sensor for detecting the displacement of the actuator, and the current application control unit increases the second current value in stages in response to an increase in the displacement detected by the detection sensor during the execution of the second application process.

[0019] In the non-contact tonometer according to another aspect of the present invention, the current application control unit stops the second application process when a predetermined time determined in advance has elapsed after the start of the first application process.

[0020] In another embodiment of the non-contact tonometer of the present invention, the non-contact tonometer includes: a projection optical system that projects a light beam to the eye to be examined while air is blown from the nozzle to the eye to be examined, and a light receiving optical system that receives reflected light of the light beam reflected by the eye to be examined and outputs an applanation signal while air is blown from the nozzle to the eye to be examined, and a current application control unit stops the second application process when a peak value of the applanation signal output from the light receiving optical system is detected during the execution of the second application process. This can reduce the amount of air blown to the eye to be examined, so-called soft puff, and thus can reduce the discomfort of the subject.

[0021] In the non-contact tonometer according to another aspect of the present invention, the actuator is a rotary actuator that moves the piston inside the cylinder via a crank mechanism.

[0022] In order to achieve the purpose of the present invention, a method for operating a non-contact tonometer is provided, wherein the non-contact tonometer comprises: a cylinder, a piston movably arranged inside the cylinder, an actuator, which moves the piston inside the cylinder by applying an electric current, compresses the air inside the cylinder by means of the piston, and a nozzle, which is connected to the inside of the cylinder and blows the air compressed by the piston toward the eye to be examined; when an electric current is applied to the actuator, a first application process of applying an electric current with a first current value to the actuator is performed, and when a predetermined switching condition is satisfied during the execution of the first application process, the first application process is switched to a second application process of applying an electric current with a second current value higher than the first current value to the actuator.

[0023] Effects of the Invention

[0024] The present invention can achieve both quietness and measurement accuracy during intraocular pressure measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a side view of the non-contact tonometer according to the first embodiment.

[0026] Figure 2 This is a schematic plan view of various optical systems in the measuring head as seen from above.

[0027] Figure 3 This is a schematic side view of various optical systems in the measuring head as seen from the side.

[0028] Figure 4 It is a functional block diagram of the control device.

[0029] Figure 5 This is a diagram showing an example of a current waveform obtained by measuring the waveform of the current applied to the electromagnetic element by the control unit during the spraying process.

[0030] Figure 6 This is a flowchart showing the flow of an intraocular pressure measurement process of a test eye in the operating method of the non-contact tonometer according to the first embodiment.

[0031] Figure 7 is a graph showing an applanation waveform based on an applanation signal continuously output from the applanation detection optical system.

[0032] Figure 8 This is an explanatory diagram for explaining the stop timing of the second application process of the non-contact tonometer according to the second embodiment.

[0033] Fig. 9 This is a flowchart showing the flow of an intraocular pressure measurement process of a subject's eye by the non-contact tonometer according to the second embodiment.

[0034] Fig.10 It is an explanatory diagram for explaining the second application process executed by the non-contact tonometer according to the third embodiment.

[0035] Description of Reference Numerals

[0036] 10…Non-contact tonometer,

[0037] 11…base,

[0038] 12…Face support,

[0039] 12a…Jaw support,

[0040] 12b… forehead guard,

[0041] 12c…pillar,

[0042] 13…mobile mechanism,

[0043] 14…Measuring head,

[0044] 15…Monitor,

[0045] 16…control device,

[0046] 21…Anterior ocular observation optical system,

[0047] 21a…front eye illumination source,

[0048] 21b…nozzle,

[0049] 21c…front eye window glass,

[0050] 21d… Chamber window glass,

[0051] 21e…half mirror,

[0052] 21f…objective lens,

[0053] 21g…half mirror,

[0054] 21i…Camera element,

[0055] 22…XY alignment sight mark projection optical system,

[0056] 22a…XY alignment light source,

[0057] 22b…condenser lens,

[0058] 22c…Aperture stop,

[0059] 22d…pinhole plate,

[0060] 22e… dichroic mirror,

[0061] 22f…collimating lens,

[0062] 23…Fixation mark projection optical system,

[0063] 23a… Fixation mark light source,

[0064] 23b…pinhole plate,

[0065] 24…Applanation detection optical system,

[0066] 24a…Lens,

[0067] 24b…pinhole plate,

[0068] 24c…Light sensor,

[0069] 25…Z alignment sight mark projection optical system,

[0070] 25a…Z alignment light source,

[0071] 25b…condenser lens,

[0072] 25c…aperture diaphragm,

[0073] 25d…pinhole plate,

[0074] 25e…collimating lens,

[0075] 26...Z alignment detection optical system,

[0076] 26a…imaging lens,

[0077] 26b…cylindrical lens,

[0078] 26c…Light sensor,

[0079] 34…Blowing mechanism,

[0080] 34a…chamber,

[0081] 34b…glass plate,

[0082] 34c…pressure sensor,

[0083] 34d... cylinder body,

[0084] 34e…Connecting pipe,

[0085] 34f…Piston,

[0086] 34g...electromagnetic components,

[0087] 34h…crankshaft mechanism,

[0088] 34i…angle detection sensor,

[0089] 40…Alignment control unit,

[0090] 42…Measurement control unit,

[0091] 44…Intraocular pressure calculation unit,

[0092] CW1…current waveform,

[0093] CW2…current waveform,

[0094] DAC1…first current value,

[0095] DAC2…second current value,

[0096] E…Examined eye,

[0097] Ec…cornea,

[0098] Ep…corneal apex,

[0099] O1…optical axis,

[0100] O2…optical axis,

[0101] O3…optical axis,

[0102] P…peak value,

[0103] PW1…Internal pressure waveform,

[0104] PW2…Internal pressure waveform,

[0105] SW… flatten the waveform,

[0106] TA…Switch timing,

[0107] W…Pulse width. DETAILED DESCRIPTION

[0108] [First embodiment]

[0109] Figure 1 FIG. 1 is a side view of the non-contact tonometer 10 according to the first embodiment. Figure 1 As shown, the non-contact tonometer 10 performs non-contact measurement of the intraocular pressure value of the test eye E. The non-contact tonometer 10 includes a base 11 , a face support 12 , a moving mechanism 13 , a measuring head 14 , a monitor 15 , and a control device 16 .

[0110] In addition, in the mutually orthogonal XYZ directions (three-axis directions) in the figure, the Y direction is the up-down direction, the Z direction is the front-back direction (also called the operation distance direction) approaching or moving away from the subject (examined eye E), and the X direction is the left-right direction perpendicular to both the up-down direction and the front-back direction. In addition, the side of the Z direction (front-back direction) close to the subject's eye E (subject) is called the Z direction front side, and the side away from the subject's eye E (subject) is called the Z direction rear side.

[0111] The base 11 is provided with a face support 12 and a moving mechanism 13 from the front side in the Z direction toward the rear side in the Z direction. The base 11 supports a measuring head 14 via the moving mechanism 13 so as to be movable in the XYZ directions.

[0112] The face support part 12 is fixed to the base 11. The face support part 12 supports the face of the subject and includes a jaw rest part 12a for receiving the jaw of the subject, a forehead stop part 12b for contacting the forehead of the subject, and a pair of pillars 12c for supporting the forehead stop part 12b.

[0113] The measuring head 14 passes from the nozzle 21b toward the cornea Ec of the inspected eye E (see Figure 2 )Blow air to deform the cornea Ec, detect its deformation state, and thereby measure the intraocular pressure value of the examined eye E without contact.

[0114] The monitor 15 is, for example, a touch-screen monitor, and is mounted on the back side of the measuring head 14. Under the control of a control device 16 described later, the monitor 15 displays various images, including a captured image (observation image) of the subject's eye E captured by the measuring head 14, a measurement result of the intraocular pressure value of the subject's eye E, and a menu screen for performing various operations and various settings.

[0115] Figure 2 This is a schematic plan view of various optical systems in the measuring head 14 as viewed from above (in the Y direction). Figure 3 This is a schematic side view of various optical systems in the measuring head 14 as viewed from the side (X direction).

[0116] like Figure 2 as well as Figure 3 As shown, the measuring head 14 has an anterior ocular observation optical system 21 , an XY alignment target projection optical system 22 , a fixation target projection optical system 23 , an applanation detection optical system 24 , a Z alignment target projection optical system 25 , a Z alignment detection optical system 26 and a blowing mechanism 34 .

[0117] The anterior ocular segment observation optical system 21 is used to observe the anterior ocular segment of the subject's eye E and the XY alignment of the measuring head 14 relative to the subject's eye E in the XY direction. An anterior ocular segment illumination light source 21a (see Figure 2 ). In addition, a nozzle 21b for blowing air and an anterior ocular window glass 21c (see Figure 3 ), chamber window glass 21d, half mirror 21e, half mirror 21g, objective lens 21f and imaging element 21i.

[0118] A plurality of anterior segment illumination light sources 21 a are provided at positions around the anterior segment window glass 21 c , and directly illuminate the anterior segment of the eye E to be examined.

[0119] The nozzle 21b and the chamber 34a of the blowing mechanism 34 (see Figure 3 ) is connected to blow air toward the cornea Ec of the eye E to be examined.

[0120] The image of the anterior segment of the eye E to be examined (image light from the anterior segment) passes through the outside of the nozzle 21b, through the anterior segment window glass 21c, the glass plate 34b described later, the chamber window glass 21d, the half-mirror 21g and the half-mirror 21e, and is imaged on the light receiving surface of the imaging element 21i by the objective lens 21f.

[0121] The imaging element 21i uses, for example, a CCD (Charge Coupled Device) type or a CMOS (complementary metal oxide semiconductor) type image sensor. The imaging element 21i captures the image of the anterior ocular segment incident on its light receiving surface and generates an imaging signal, and outputs the imaging signal to the control device 16. Thus, under the control of the control device 16, the observation image of the anterior ocular segment of the subject's eye E based on the imaging signal output from the imaging element 21i is displayed on the monitor 15.

[0122] In addition, the anterior ocular observation optical system 21 guides the reflected light of the XY alignment sight mark light projected from the XY alignment sight mark projection optical system 22 described later to the subject's eye E, which is reflected by the cornea Ec, to the light receiving surface of the imaging element 21i. The reflected light passes through the nozzle 21b, the chamber window glass 21d, the half mirror 21g and the half mirror 21e, and is imaged on the light receiving surface of the imaging element 21i by the objective lens 21f. As a result, an XY point is formed on the light receiving surface of the imaging element 21i at a position corresponding to the positional relationship (relative position) between the measuring head 14 and the cornea Ec in the XY direction. As a result, an XY alignment detection can be performed to detect the relative position of the subject's eye E relative to the measuring head 14 in the XY direction.

[0123] The imaging element 21i images the XY point formed on its light receiving surface and outputs an imaging signal of the XY point to the control device 16. Thus, under the control of the control device 16, the observation image of the anterior ocular segment and the XY point are superimposed and displayed on the monitor 15. In addition, the monitor 15 also displays an alignment auxiliary mark.

[0124] The XY alignment target projection optical system 22 is equivalent to the projection optical system of the present invention, and projects the XY alignment target light, which is equivalent to the light beam of the present invention, from the front to the cornea Ec of the inspected eye E. The XY alignment target light is used for XY alignment of the measuring head 14 relative to the inspected eye E. In addition, the XY alignment target light is also used for measuring the intraocular pressure value of the inspected eye E. Hereinafter, the reflected light of the XY alignment target light reflected by the cornea Ec is abbreviated as "XY target reflected light".

[0125] The XY alignment sight mark projection optical system 22 includes an XY alignment light source 22a, a condenser lens 22b, an aperture stop 22c, a pinhole plate 22d, a dichroic mirror 22e, and a collimator lens 22f (see Figure 3 ) In addition, the XY alignment target projection optical system 22 and the anterior ocular segment observation optical system 21 share the half mirror 21e.

[0126] The XY alignment light source 22a emits infrared rays. The collimating lens 22f is arranged on the optical path of the XY alignment sight mark projection optical system 22 so that its focus coincides with the pinhole plate 22d. The infrared rays emitted from the XY alignment light source 22a are converged by the condenser lens 22b and pass through the aperture stop 22c, and are guided to the hole portion of the pinhole plate 22d.

[0127] The infrared light that has passed through the hole of the pinhole plate 22d is reflected by the dichroic mirror 22e and guided to the collimating lens 22f, and then becomes parallel light in the collimating lens 22f and is emitted from the collimating lens 22f to the half mirror 21e. After being reflected by the half mirror 21e, the parallel light of the infrared light travels along the optical axis O1 of the anterior ocular observation optical system 21. Thus, after passing through the half mirror 21g and the chamber window glass 21d, the parallel light of the infrared light passes through the inside of the nozzle 21b, and thus enters the subject's eye E as XY alignment sight mark light.

[0128] Although illustration of the XY alignment target light incident on the subject's eye E is omitted, the light is reflected by the surface of the cornea Ec to form an XY point. In addition, the aperture stop 22c is provided at a position conjugate with the corneal apex Ep of the cornea Ec with respect to the collimator lens 22f.

[0129] The fixation mark projection optical system 23 projects a fixation mark onto the inspected eye E. The fixation mark projection optical system 23 includes a fixation mark light source 23a and a pinhole plate 23b (see Figure 3 ). In addition, the fixation target projection optical system 23 shares the dichroic mirror 22e and the collimating lens 22f with the XY alignment target projection optical system 22, and shares the half mirror 21e with the anterior ocular segment observation optical system 21.

[0130] The fixation mark light source 23a emits visible light as fixation mark light. The fixation mark light is guided to the hole of the pinhole plate 23b, and after passing through the hole of the pinhole plate 23b and the dichroic mirror 22e, it is emitted toward the collimating lens 22f. Then, after being converted into approximately parallel light by the collimating lens 22f, the fixation mark light is emitted toward the half mirror 21e, and is reflected by the half mirror 21e, thereby traveling along the optical axis O1 of the anterior ocular observation optical system 21. Thus, after passing through the half mirror 21g and the chamber window glass 21d, the fixation mark light passes through the inside of the nozzle 21b and reaches the subject's eye E. By having the subject fixate on the fixation mark as a fixation target, the subject's line of sight can be fixed.

[0131] Applanation detection optical system 24 (refer to Figure 3) corresponds to the light receiving optical system of the present invention, receives the reflected light of the XY sight mark, and outputs an applanation signal (also called a corneal deformation signal) as a light receiving signal indicating the light amount of the reflected light of the XY sight mark. The applanation detection optical system 24 has a lens 24a, a pinhole plate 24b, and a light receiving sensor 24c, and shares a half mirror 21g with the anterior ocular segment observation optical system 21.

[0132] When the surface of the cornea Ec is a flat surface, the lens 24a focuses the reflected light of the XY sight mark on the opening of the pinhole plate 24b. The opening of the pinhole plate 24b is provided at the focal position of the lens 24a.

[0133] The light receiving sensor 24 c is, for example, a photodiode that outputs an applanation signal corresponding to the amount of light reflected from the received XY sight mark, and outputs the applanation signal to the control device 16 .

[0134] The XY sight mark reflected light passes through the nozzle 21b, passes through the chamber window glass 21d, and reaches the half mirror 21g. Then, a part of the XY sight mark reflected light is reflected by the half mirror 21g, and then enters the pinhole plate 24b through the lens 24a.

[0135] When the surface of the cornea Ec is brought into a flattened state (flattened state) by the blowing of air from the nozzle 21b, the applanation detection optical system 24 causes the entire XY sight mark reflected light traveling in the applanation detection optical system 24 to pass through the pinhole plate 24b and reach the light receiving sensor 24c. In addition, when the cornea Ec is in a state other than the applanation state, the applanation detection optical system 24 causes the XY sight mark reflected light to reach the light receiving sensor 24c after being partially blocked by the pinhole plate 24b. Therefore, the signal intensity of the detection signal of the XY sight mark reflected light output from the applanation detection optical system 24 gradually increases as the surface of the cornea Ec changes from the convex state to the applanation state, and gradually decreases as it changes from the applanation state to the concave state.

[0136] Z is aligned with the sight mark projection optical system 25 (refer to Figure 2 ) projects the Z alignment sight mark light for Z alignment in the Z-axis direction to the cornea Ec from an oblique direction. The Z alignment sight mark projection optical system 25 has a Z alignment light source 25a, a condenser lens 25b, an aperture stop 25c, a pinhole plate 25d and a collimating lens 25e along the optical axis O2.

[0137] The Z alignment light source 25a emits infrared light (for example, a wavelength of 860 nm). The aperture stop 25c is provided at a position conjugate with the corneal apex Ep with respect to the collimator lens 25e. The collimator lens 25e is arranged so that the focal point coincides with the hole of the pinhole plate 25d.

[0138] The infrared light emitted from the Z alignment light source 25a is focused by the focusing lens 25b and passes through the aperture stop 25c to the pinhole plate 25d. Then, the infrared light that has passed through the hole of the pinhole plate 25d is converted into parallel light by the collimating lens 25e, enters the subject's eye E as Z alignment sight mark light, and is reflected by the cornea Ec, thereby forming a bright spot image in the subject's eye E.

[0139] The Z alignment detection optical system 26 receives the reflected light of the Z alignment sight mark light reflected by the cornea Ec (hereinafter referred to as the Z sight mark reflected light), and detects the positional relationship between the measuring head 14 and the cornea Ec in the Z-axis direction. The Z alignment detection optical system 26 includes an imaging lens 26a, a cylindrical lens 26b, and a light receiving sensor 26c along the optical axis O3.

[0140] The cylindrical lens 26b used has optical power in the Y-axis direction. The light receiving sensor 26c is a sensor capable of detecting the light receiving position of the light reflected by the Z sight mark on its light receiving surface, and for example, a linear sensor or a PSD (Position Sensitive Detector) can be used.

[0141] The reflected light of the Z sight mark is condensed by the imaging lens 26 a and then travels toward the cylindrical lens 26 b , where it is condensed in the Y-axis direction by the cylindrical lens 26 b , thereby forming a bright spot image on the light receiving sensor 26 c .

[0142] In the XZ plane, the light receiving sensor 26c is in a positional relationship conjugate with the aforementioned bright spot image formed on the subject's eye E by the Z alignment sight mark projection optical system 25 with respect to the imaging lens 26a. In addition, in the YZ plane, the light receiving sensor 26c is in a positional relationship conjugate with respect to the imaging lens 26a and the cylindrical lens 26b and the corneal vertex Ep. That is, the light receiving sensor 26c is in a conjugate relationship conjugate with the aperture stop 25c, so even if the cornea Ec is misaligned in the Y direction, the Z sight mark reflected light on the surface of the cornea Ec can be efficiently incident on the light receiving sensor 26c. In addition, the light receiving sensor 26c outputs a detection signal (hereinafter referred to as a Z detection signal) of the Z sight mark reflected light focused by the cylindrical lens 26b to the control device 16. This Z detection signal shows the relative position of the subject's eye E with respect to the measuring head 14 in the Z direction, and more specifically, shows the distance between the measuring head 14 and the subject's eye E (corneal vertex Ep) in the Z direction. In this way, Z alignment detection can be performed.

[0143] Blowing mechanism 34 (see Figure 3 ) has, in addition to the nozzle 21b already described, a chamber 34a, a glass plate 34b, a pressure sensor 34c, a cylinder 34d, a connecting pipe 34e, a piston 34f, an electromagnetic element 34g, a crank mechanism 34h and an angle detection sensor 34i.

[0144] The nozzle 21b is installed in the chamber 34a via a transparent glass plate 34b. In addition, a chamber window glass 21d is provided in the chamber 34a at a position facing the nozzle 21b. In addition, a pressure sensor 34c is provided in the chamber 34a. The pressure sensor 34c outputs a pressure detection signal indicating the pressure (internal pressure) inside the chamber 34a to the control device 16.

[0145] The cylinder 34d is connected to the chamber 34a via the connecting pipe 34e. Thus, the interior of the cylinder 34d is connected to the interior of the chamber 34a via the connecting pipe 34e, and thus the interior of the cylinder 34d is connected to the nozzle 21b. In addition, a piston 34f is movably provided inside the cylinder 34d. The cylinder 34d and the piston 34f constitute an air compression chamber.

[0146] The electromagnetic element 34g is a rotating electromagnetic element that rotates by applying an electric current, which is equivalent to the actuator and the rotary actuator of the present invention. The electromagnetic element 34g is connected to the piston 34f via a crank mechanism 34h that converts its rotational motion into a linear motion. The electromagnetic element 34g rotates by applying an electric current under the control of the control device 16, thereby causing the piston 34f to move linearly inside the cylinder 34d via the crank mechanism 34h, thereby compressing the air in the cylinder 34d. As a result, air is sprayed from the nozzle 21b to the cornea Ec via the connecting pipe 34e and the chamber 34a.

[0147] In addition, in the blowing mechanism 34, the internal pressure of the chamber 34a is detected by the pressure sensor 34c, thereby being able to obtain the pressure of the air when the air is blown from the nozzle 21b toward the cornea Ec.

[0148] The angle detection sensor 34i is equivalent to the detection sensor of the present invention, detects the rotation angle of the electromagnetic element 34g which is equivalent to the displacement of the actuator of the present invention, and outputs its detection result to the control device 16. The rotation angle of the electromagnetic element 34g detected by the angle detection sensor 34i indirectly shows the internal pressure of the chamber 34a, which can be used in the drive control of the electromagnetic element 34g described in detail later. In addition, when the detection result of the angle detection sensor 34i is not used for the drive control of the electromagnetic element 34g, the angle detection sensor 34i can be omitted.

[0149] Figure 4 is a functional block diagram of the control device 16. Figure 4As shown, the control device 16 performs overall control over the operation of the non-contact tonometer 10. The control device 16 has a computing circuit composed of various processors (Processor) and memories. Various processors include CPU (Central Processing Unit), GPU (Graphics Processing Unit), ASIC (Application Specific Integrated Circuit) and programmable logic devices (such as SPLD (Simple Programmable Logic Devices), CPLD (Complex Programmable Logic Device), and FPGA (Field Programmable Gate Arrays)). In addition, the various functions of the control device 16 can be implemented by one processor or by multiple processors of the same type or different types.

[0150] The above-described moving mechanism 13 , measuring head 14 , monitor 15 , and the like are connected to the control device 16 . The control device 16 controls the operation of the non-contact tonometer 10 as a whole.

[0151] The control device 16 functions as the alignment control unit 40, the measurement control unit 42, and the intraocular pressure value calculation unit 44 by reading and executing a control program not shown. In addition, the structure described as the "~ part" of the control device 16 may also be a "~ circuit", "~ device" or "~ equipment". That is, the structure described as the "~ part" may also be composed of any one of firmware, software and hardware or a combination thereof.

[0152] The alignment control unit 40 operates when measuring the intraocular pressure of the eye E to be examined, and controls automatic alignment of the measuring head 14 with respect to the eye E to be examined in the XYZ directions.

[0153] Specifically, the alignment control unit 40 controls the anterior ocular observation optical system 21 and the XY alignment target projection optical system 22 described above to perform an XY alignment detection to detect the relative position of the examined eye E relative to the measuring head 14 in the XY direction. In addition, the alignment control unit 40 controls the Z alignment target projection optical system 25 and the Z alignment detection optical system 26 to perform a Z alignment detection to detect the relative position of the examined eye E relative to the measuring head 14 in the Z direction. In addition, the XY alignment detection and Z alignment detection of the non-contact tonometer 10 are well-known technologies, and therefore, a detailed description thereof is omitted here. Next, based on the XYZ alignment detection result, the alignment control unit 40 drives the moving mechanism 13 to perform automatic alignment of the measuring head 14 relative to the examined eye E in the XYZ direction.

[0154] After the automatic alignment is completed, the measurement control unit 42 operates the blowing mechanism 34 to perform a blowing process of blowing air from the nozzle 21b of the blowing mechanism 34 toward the cornea Ec. Specifically, the measurement control unit 42 drives the electromagnetic element 34g to rotate (current drive) by applying current to the electromagnetic element 34g, thereby moving the piston 34f toward the inner side of the cylinder body 34d via the crank mechanism 34h. Therefore, the measurement control unit 42 is equivalent to the current application control unit of the present invention. At this time, the measurement control unit 42 applies current to the electromagnetic element 34g under the conditions of taking into account the silencing of the sound generated by the blowing mechanism 34 and ensuring the measurement accuracy of the intraocular pressure measurement.

[0155] Figure 5 1 is a diagram showing an example of a current waveform CW1 which is a waveform of a current applied to the electromagnetic element 34g by the measurement control unit 42 during the spraying process.

[0156] also, Figure 5 The reference symbol CW2 in FIG. 1 is an example of a current waveform of a comparative example in which only the sound generated by the blowing mechanism 34 is silenced. Figure 5 The reference symbol PW1 in FIG. 1 is an example of an internal pressure waveform showing a time change of the pressure (internal pressure) inside the chamber 34a detected by the pressure sensor 34c when the current of the current waveform CW1 is applied to the electromagnetic element 34g by the measurement control unit 42. Figure 5 The reference symbol PW2 in FIG. 4 is an internal pressure waveform showing a time change of the pressure inside the chamber 34a detected by the pressure sensor 34c when the measurement control unit 42 applies the current waveform CW2 to the electromagnetic element 34g. In addition, Figure 5 Reference symbol W in refs. 3 shows the pulse width of the current waveforms CW1 and CW2, that is, the application period of the current applied to the electromagnetic element 34g.

[0157] like Figure 5As shown in FIG. 1 , in order to quiet the sound generated by the blowing mechanism 34 during the blowing process, it is necessary to reduce the current value of the current applied to the electromagnetic element 34g by the measurement control unit 42. Therefore, the measurement control unit 42 applies a first current value DAC1 to the electromagnetic element 34g. The first current value DAC1 is a current value for quieting the sound generated by the blowing mechanism 34, for example, a minimum current value capable of driving the piston 34f. The first current value DAC1 is appropriately determined by experiments or simulations.

[0158] At this time, as shown in the current waveform CW2 of the comparative example, during the entire period of the pulse width W, if the current value of the current applied to the electromagnetic element 34g is maintained at a constant first current value DAC1, the torque generated by the electromagnetic element 34g is constant. On the other hand, as the electromagnetic element 34g rotates continuously, the force required to compress the air in the chamber 34a increases. Therefore, if the current value of the current applied to the electromagnetic element 34g is maintained at a constant first current value DAC1, as the electromagnetic element 34g rotates, the force applied to the piston 34f via the crank mechanism 34h weakens. As a result, as shown in the internal pressure waveform PW2 of the comparative example, the pressure of the air in the chamber 34a does not rise, and the pressure of the air blown from the nozzle 21b to the cornea Ec is insufficient. In this case, the intraocular pressure value of the eye E to be examined cannot be measured with good accuracy.

[0159] Therefore, as shown in the current waveform CW1, the measurement control unit 42 performs the first application process at the first operation of the spray process, and in the first application process, the current value of the current applied to the electromagnetic element 34g is constantly maintained at the first current value DAC1. Then, the measurement control unit 42 performs the second application process at the switching timing TA that satisfies the predetermined switching condition during the execution of the first application process, and in the second application process, the current value of the current applied to the electromagnetic element 34g is increased to a second current value DAC2 higher than the first current value DAC1, and the current of the second current value DAC2 is applied to the electromagnetic element 34g.

[0160] The switching condition (hereinafter, simply referred to as the micro-switching condition) for switching from the first application process to the second application process can be determined in such a manner that the force transmitted from the electromagnetic element 34g to the piston 34f does not decrease even when the electromagnetic element 34g rotates. Specifically, in the present embodiment, during the execution of the first application process, when the pressure detected by the pressure sensor 34c reaches a predetermined pressure threshold, the first application process is switched to the second application process. Therefore, the measurement control unit 42 starts the first application process at the first operation of the spraying process, and thereafter, continues the first application process until the pressure detected by the pressure sensor 34c reaches the pressure threshold.

[0161] Then, when the pressure detected by the pressure sensor 34c reaches the pressure threshold value (switching timing TA) during the execution of the first application process, the measurement control unit 42 increases the current value applied to the electromagnetic element 34g from the first current value DAC1 to the second current value DAC2, thereby switching from the first application process to the second application process. As a result, the slope of the internal pressure waveform PW1 can be maintained substantially constant, and the pressure of the air in the chamber 34a can be sufficiently high. The pressure threshold value and the second current value DAC2 are set to values ​​that can maintain the slope of the internal pressure waveform PW1 substantially constant through experiments or simulations.

[0162] In addition, there is a correlation between the pressure detected by the pressure sensor 34c and the rotation angle of the electromagnetic element 34g detected by the angle detection sensor 34i during the spraying process. Therefore, instead of the above-mentioned switching condition, when the rotation angle detected by the angle detection sensor 34i reaches a predetermined angle threshold (displacement threshold of the present invention) during the execution of the first application process, the second application process can be switched. In this case, the measurement control unit 42 continues the first application process until the rotation angle detected by the angle detection sensor 34i reaches the angle threshold, and switches to the second application process when the rotation angle detected by the angle detection sensor 34i reaches the angle threshold (switching timing TA).

[0163] When a predetermined time (equivalent to the time of the pulse width W) has passed after the start of the first application process, the measurement control unit 42 stops applying the current to the electromagnetic element 34g, thereby stopping the second application process. In addition, the measurement control unit 42 may start timing after starting the second application process, and stop the second application process when a predetermined time has passed. That is, the timing of starting the timing of the above-mentioned predetermined time is not particularly limited.

[0164] Back to Figure 4 During the execution of the blowing process, the measurement control unit 42 continuously performs the projection process of the XY alignment target light on the cornea Ec by the XY alignment target projection optical system 22 and the reception of the XY target reflected light by the applanation detection optical system 24 and the signal output process including the output of the applanation signal.

[0165] The intraocular pressure value calculation unit 44 calculates the intraocular pressure value of the examined eye E based on the applanation signal continuously output from the applanation detection optical system 24 and the detection result of the pressure sensor 34c. For example, the intraocular pressure value calculation unit 44 calculates the applanation waveform SW (see Figure 7The intraocular pressure value calculation unit 44 calculates the intraocular pressure value of the eye under examination E by a known method based on the signal intensity (light amount) of the applanation signal corresponding to the centroid position of the peak value or the maximum value and the detection result (air pressure) of the pressure sensor 34c. The method for calculating the intraocular pressure value of the eye under examination E is not limited to the above method, and various known methods can be used.

[0166] [Function of the first embodiment]

[0167] Figure 6 This is a flowchart showing the operating method of the non-contact tonometer 10 of the first embodiment having the above-described configuration, that is, the flow of an intraocular pressure measurement process of the examined eye E.

[0168] like Figure 6 As shown, after the subject's face is placed on the face support 12 , when the examiner inputs an intraocular pressure measurement start operation to an operation unit (not shown), the control device 16 functions as an alignment control unit 40 , a measurement control unit 42 , and an intraocular pressure value calculation unit 44 .

[0169] Initially, the alignment control unit 40 controls the anterior ocular segment observation optical system 21 and the XY alignment target projection optical system 22 to perform XY alignment detection, and controls the Z alignment target projection optical system 25 and the Z alignment detection optical system 26 to perform Z alignment detection. Next, the alignment control unit 40 drives the moving mechanism 13 to perform automatic alignment of the measuring head 14 in the XYZ direction relative to the eye E to be examined based on the XYZ alignment detection result (step S1).

[0170] After the automatic alignment is completed, the measurement control unit 42 operates the blowing mechanism 34 to perform the blowing process. At this time, when the blowing process is first operated, the measurement control unit 42 starts the first application process of applying the current of the first current value DAC1 to the electromagnetic element 34g (step S2). In addition, the measurement control unit 42 monitors the pressure detected by the pressure sensor 34c and continues the first application process until the pressure reaches the pressure threshold, that is, the switching condition is met (no in step S3). At this stage, the low first current value DAC1 is applied to the electromagnetic element 34g, so that the sound generated by the blowing mechanism 34 can be silenced.

[0171] Furthermore, when the pressure detected by the pressure sensor 34c reaches the pressure threshold during the execution of the first application process, that is, when the switching condition is satisfied (Yes in step S3), the measurement control unit 42 increases the current value applied to the electromagnetic element 34g to the second current value DAC2, thereby executing the switch from the first application process to the second application process (steps S4 and S5). Figure 5As shown, the slope of the internal pressure waveform PW1 is maintained substantially constant before and after the switching timing TA, and the pressure of the air in the chamber 34 a can be made sufficiently high.

[0172] Furthermore, when the rotation angle of the electromagnetic element 34g detected by the angle detection sensor 34i during the execution of the first application process reaches an angle threshold, the measurement control unit 42 may determine that the switching condition is satisfied and execute the switch from the first application process to the second application process.

[0173] The measurement control unit 42 continues the second application process, maintaining the current value applied to the electromagnetic element 34g at the second current value DAC2 until a predetermined time has passed after the first application process is started (step S6, no in step S7). Then, when the predetermined time has passed (yes in step S7), the measurement control unit 42 stops applying the current to the electromagnetic element 34g, thereby stopping the second application process (step S8).

[0174] In addition, during the blowing process, the measurement control unit 42 continuously performs the projection process of the XY alignment target light onto the cornea Ec by the XY alignment target projection optical system 22 and the reception of the XY target reflected light by the applanation detection optical system 24 and the signal output process including the output of the applanation signal.

[0175] When the puffing process is completed, the intraocular pressure value calculation unit 44 calculates the centroid position or the maximum value of the peak value of the applanation waveform SW based on the applanation signal output from the applanation detection optical system 24. Then, the intraocular pressure value calculation unit 44 calculates the intraocular pressure value of the inspected eye E based on the signal intensity (light amount) of the applanation signal corresponding to the centroid position or the maximum value of the peak value and the detection result (air pressure) of the pressure sensor 34c (step S9).

[0176] Figure 7 is a graph showing an applanation waveform SW based on an applanation signal continuously output from the applanation detection optical system 24. In addition, Figure 7 The reference numeral 7A is in the already described Figure 5 The current waveform CW2 of the comparative example shown is an example of a flattened waveform SW obtained when a current is applied to the electromagnetic element 34g. Figure 7 The reference numeral 7B is a reference to the already described Figure 5 The current waveform CW1 of the present embodiment shown is an example of a flattened waveform SW obtained when a current is applied to the electromagnetic element 34g.

[0177] When the current value of the current applied to the electromagnetic element 34g is fixed to the first current value DAC1 for the purpose of only silencing the sound generated by the blowing mechanism 34, as described above, Figure 5As shown in the internal pressure waveform PW2, the pressure of the air in the chamber 34a is not sufficiently increased. Figure 7 As shown in the figure mark 7A, the flattened waveform SW fails to become a normal waveform (refer to Figure 7 7B), it is difficult to detect the peak value from the applanation waveform SW. Therefore, the measurement accuracy of the intraocular pressure value of the eye E to be examined is reduced.

[0178] In contrast, in this embodiment, if Figure 7 As shown in the figure 7B, by increasing the current value of the current applied to the electromagnetic element 34g during the blowing process from the first current value DAC1 to the second current value DAC2, the pressure of the air in the chamber 34a can be sufficiently high. Figure 7 As shown in the reference numeral 7B, the applanation waveform SW becomes a normal waveform, and therefore the intraocular pressure value calculation unit 44 can accurately detect the peak of the applanation waveform SW. This prevents the measurement accuracy of the intraocular pressure value of the eye E from being reduced.

[0179] As described above, the non-contact tonometer 10 of the first embodiment applies a current of the first current value DAC1 to the electromagnetic element 34g during the first operation of the blowing process, thereby achieving silencing of the sound generated by the blowing mechanism 34, and increasing the current value applied to the electromagnetic element 34g to the second current value DAC2 during the blowing process, thereby preventing a decrease in the measurement accuracy of the intraocular pressure value of the inspected eye E. As a result, the non-contact tonometer 10 of the first embodiment can achieve both silencing and measurement accuracy during intraocular pressure measurement.

[0180] [Second Embodiment]

[0181] In the non-contact tonometer 10 of the first embodiment, the second application process is stopped when a predetermined time (equivalent to the time of the pulse width W) has passed since the start of the first application process. In contrast, in the non-contact tonometer 10 of the second embodiment, the second application process is stopped at a different stop timing from that of the first embodiment.

[0182] The configuration of the non-contact tonometer 10 of the second embodiment is basically the same as that of the non-contact tonometer 10 of the first embodiment, and therefore, components having the same functions or configurations as those of the first embodiment are denoted by the same reference numerals and their description is omitted.

[0183] Figure 8 1 is an explanatory diagram for explaining the stop timing of the second application process of the non-contact tonometer 10 according to the second embodiment. Figure 8As shown, the measurement control unit 42 of the non-contact tonometer 10 of the second embodiment continuously calculates, for example, the slope of the applanation waveform SW based on the applanation signal continuously output from the applanation detection optical system 24 during the execution of the second application process, thereby detecting the peak value P of the applanation waveform SW. Then, the measurement control unit 42 of the second embodiment stops applying the current to the electromagnetic element 34g when the peak value P of the applanation waveform SW is detected, thereby stopping the second application process.

[0184] Fig. 9 1 is a flowchart showing the flow of the intraocular pressure measurement process of the subject's eye E by the non-contact tonometer 10 of the second embodiment. In addition, the processes from step S1 to step S6 are the same as those already described. Figure 6 The processes from step S1 to step S6 of the first embodiment shown are the same, and therefore, the detailed description is omitted here.

[0185] The measurement control unit 42 continues the second application process until the peak value P of the applanation waveform SW is detected based on the applanation signal continuously output from the applanation detection optical system 24 during the execution of the second application process, and maintains the current value of the current applied to the electromagnetic element 34g at the second current value DAC2 (step S6, no in step S7A). Then, when the peak value P of the applanation waveform SW is detected (yes in step S7A), the measurement control unit 42 stops applying the current to the electromagnetic element 34g, thereby stopping the second application process (step S8). The subsequent processing is the same as that described above. Figure 6 The first embodiment is the same as shown, and the detailed description is omitted here.

[0186] As described above, in the non-contact tonometer 10 of the second embodiment, the first current value DAC1 is applied to the electromagnetic element 34g at the first operation of the blowing process, and the current value of the current applied to the electromagnetic element 34g is increased to the second current value DAC2 during the blowing process, thereby obtaining the same effect as the first embodiment. In addition, the second application process is stopped after the peak value P of the flattening waveform SW is detected, thereby reducing the amount of air blown to the subject's eye E, which is a so-called soft puff, thereby reducing the subject's discomfort.

[0187] [Third Embodiment]

[0188] Fig.10It is an explanatory diagram for explaining the second application process performed by the non-contact tonometer 10 of the third embodiment. In the non-contact tonometer 10 of each of the above-mentioned embodiments, the setting value of the second current value DAC2 in the second application process is 1. Therefore, when the switching condition for switching to the second application process is satisfied during the execution of the first application process, the measurement control unit 42 of each of the above-mentioned embodiments increases the current value of the current applied to the electromagnetic element 34g to the 1 second current value DAC2 and maintains it as the second current value DAC2. In contrast, the non-contact tonometer 10 of the third embodiment performs a second application process different from that of the above-mentioned embodiments.

[0189] In addition, the non-contact tonometer 10 of the third embodiment is basically the same in structure as the non-contact tonometer 10 of the above-mentioned embodiments except for the difference in the method of applying the second processing. Therefore, the same figure marks are marked for the components that are the same in function or structure as those of the above-mentioned embodiments, and their descriptions are omitted.

[0190] like Fig.10 As shown, in the contact tonometer 10 of the third embodiment, a plurality of second current value DAC2 are provided. Furthermore, when the switching condition for switching to the second application process is satisfied during the execution of the first application process, the measurement control unit 42 of the non-contact tonometer 10 of the third embodiment makes the second current value DAC2 of the current applied to the electromagnetic element 34g stepwise increase in a plurality of stages.

[0191] Specifically, the pressure threshold is pre-set for each second current value DAC2. At this time, in response to the second current value DAC2 being increased in a stepwise manner, the pressure threshold is set to be increased in a stepwise manner. Moreover, the measurement control unit 42 applies the current of the second current value DAC2 corresponding to the pressure threshold to the electromagnetic element 34g whenever the pressure detected by the pressure sensor 34c during the execution of the second application process reaches the pressure threshold. Thus, the measurement control unit 42 can make the second current value DAC2 increase in a stepwise manner in response to the increase in the pressure detected by the pressure sensor 34c during the execution of the second application process.

[0192] In addition, the above-mentioned angle threshold value can be pre-set for each second current value DAC2. At this time, in response to the second current value DAC2 being stepped up, the angle threshold value is set to be stepped up. Moreover, the measurement control unit 42 applies a current of the second current value DAC2 corresponding to the angle threshold value to the electromagnetic element 34g whenever the rotation angle of the electromagnetic element 34g detected by the angle detection sensor 34i during the execution of the second application process reaches the angle threshold value. Thus, the measurement control unit 42 can make the second current value DAC2 stepwise higher in response to the increase in the rotation angle of the electromagnetic element 34g detected by the angle detection sensor 34i during the execution of the second application process.

[0193] Furthermore, the measurement control unit 42 may increase the second current value DAC2 of the current applied to the electromagnetic element 34g in a stepwise manner whenever the pressure detected by the pressure sensor 34c or the rotation angle detected by the angle detection sensor 34i increases by a certain amount during the execution of the second application process.

[0194] As described above, in the non-contact tonometer 10 of the third embodiment, by applying a current of the first current value DAC1 to the electromagnetic element 34g during the first operation of the blowing process, and increasing the second current value DAC2 of the current applied to the electromagnetic element 34g in a step-by-step manner during the blowing process, the same effect as the above-mentioned embodiments can be obtained.

[0195] [also]

[0196] In the above-described embodiments, the piston 34f is driven by the electromagnetic element 34g, but a rotary actuator other than the electromagnetic element 34g may be used to drive the piston 34f. Furthermore, an actuator other than the rotary actuator may be used as long as it can drive the piston 34f.

[0197] In the above-mentioned embodiments, the non-contact tonometer 10 is described as an example, but the present invention is also applicable to a composite device capable of measuring the intraocular pressure value of the subject's eye E and eye characteristics other than the intraocular pressure value of the subject's eye E.

Claims

1. A non-contact tonometer, characterized in that: have: Cylinder body, The piston is movably arranged inside the cylinder. an actuator, which moves the piston inside the cylinder by applying an electric current, thereby compressing the air inside the cylinder by means of the piston, a nozzle connected to the interior of the cylinder and blowing the air compressed by the piston toward the eye to be examined, and a current application control unit for applying the current to the actuator; The current application control unit executes a first application process of applying the current to the actuator at a first current value, and when a predetermined switching condition is satisfied during the execution of the first application process, switches from the first application process to a second application process of applying the current to the actuator at a second current value higher than the first current value.

2. The non-contact tonometer according to claim 1, characterized in that: The nozzle is in communication with the interior of the cylinder via a chamber in communication with the interior of the cylinder, The non-contact tonometer includes a pressure sensor for detecting the pressure inside the chamber. The current application control unit determines whether the switching condition is satisfied based on whether the pressure detected by the pressure sensor reaches a predetermined pressure threshold.

3. The non-contact tonometer according to claim 1, characterized in that: The non-contact tonometer includes a detection sensor for detecting a displacement amount of the actuator. The current application control unit determines whether the switching condition is satisfied based on whether the displacement amount detected by the detection sensor reaches a predetermined displacement amount threshold.

4. The non-contact tonometer according to any one of claims 1 to 3, characterized in that: The current application control unit increases the second current value in a stepwise manner during execution of the second application process.

5. The non-contact tonometer according to claim 4, characterized in that: The nozzle is in communication with the interior of the cylinder via a chamber in communication with the interior of the cylinder, The non-contact tonometer has a pressure sensor for detecting the pressure inside the chamber. The current application control unit increases the second current value in a stepwise manner in response to an increase in the pressure detected by the pressure sensor during execution of the second application process.

6. The non-contact tonometer according to claim 4, characterized in that: The non-contact tonometer includes a detection sensor for detecting a displacement amount of the actuator. The current application control unit increases the second current value in a stepwise manner in response to an increase in the displacement amount detected by the detection sensor during execution of the second application process.

7. The non-contact tonometer according to any one of claims 1 to 3, characterized in that: The current application control unit stops the second application process when a predetermined time period determined in advance has elapsed after the first application process was started.

8. The non-contact tonometer according to any one of claims 1 to 3, characterized in that: The non-contact tonometer has: a projection optical system for projecting a light beam onto the eye to be examined while the air is being blown from the nozzle toward the eye to be examined, and a light receiving optical system that receives reflected light of the light beam reflected by the eye to be examined and outputs an applanation signal while the air is being blown from the nozzle toward the eye to be examined, The current application control unit stops the second application process when detecting a peak value of the applanation signal output from the light receiving optical system during execution of the second application process.

9. The non-contact tonometer according to any one of claims 1 to 3, characterized in that: The actuator is a rotary actuator that moves the piston inside the cylinder via a crank mechanism.

10. A method for operating a non-contact tonometer, characterized in that: The non-contact tonometer has: Cylinder body, The piston is movably arranged inside the cylinder. an actuator that moves the piston inside the cylinder by applying an electric current, compressing the air inside the cylinder by means of the piston, and a nozzle, connected to the interior of the cylinder, for spraying the air compressed by the piston toward the eye to be examined; When the current is applied to the actuator, a first application process of applying the current to the actuator with a first current value is performed, and when a predetermined switching condition is satisfied during the execution of the first application process, the first application process is switched to a second application process of applying the current to the actuator with a second current value higher than the first current value.

Images