JP7247561B2 - ultrasonic tonometer - Google Patents

Description

The present disclosure relates to an ultrasonic tonometer that measures the intraocular pressure of an eye to be examined using ultrasonic waves.

As a non-contact type tonometer, an air injection type tonometer is still common. The air injection tonometer detects the deformation state of the cornea when air is injected into the cornea and the air pressure injected into the cornea, and converts the air pressure in the predetermined deformation state into the intraocular pressure.

As a non-contact type tonometer, an ultrasonic tonometer that measures intraocular pressure using ultrasonic waves has been proposed (see Patent Document 1). The ultrasonic tonometer disclosed in Patent Document 1 detects the deformation state of the cornea when ultrasonic waves are emitted to the cornea and the radiation pressure emitted to the cornea, thereby measuring the radiation pressure in the predetermined deformation state to the intraocular pressure. is converted to

Further, as an ultrasonic tonometer, a device for measuring intraocular pressure based on the relationship between the characteristics (amplitude and phase) of reflected waves from the cornea and intraocular pressure has been proposed (see Patent Document 2).

Japanese Patent Laid-Open No. 5-253190 JP 2009-268651

However, the conventional apparatus cannot properly irradiate the cornea of the subject's eye with ultrasonic waves. For example, the apparatus of Patent Document 1 cannot properly irradiate the cornea with ultrasonic waves, and cannot actually apply ultrasonic waves to the subject's eye to the extent that the cornea is flattened or depressed. Further, for example, the apparatus disclosed in Patent Document 2 cannot properly irradiate the cornea with ultrasonic waves and cannot sufficiently detect the characteristics of the reflected waves.

In view of the conventional problems, the technical problem of the present disclosure is to provide a non-contact ultrasonic tonometer that can appropriately irradiate an eye to be examined with ultrasonic waves.

In order to solve the above problems, the present disclosure is characterized by having the following configurations.

(1) An ultrasonic tonometer for measuring the intraocular pressure of an eye to be examined using ultrasonic waves, the ultrasonic tonometer having an ultrasonic element and comprising a plurality of ultrasonic actuators for irradiating the eye to be examined with ultrasonic waves; The ultrasonic actuator is characterized in that the eye to be examined is deformed by irradiating the eye with ultrasonic waves from two or more directions.
(2) An ultrasonic tonometer for measuring the intraocular pressure of an eye to be examined using ultrasonic waves, comprising an optical element, an optical unit for optically acquiring information on the eye to be examined, and an ultrasonic element. and an ultrasonic actuator for irradiating the eye to be examined with ultrasonic waves, wherein the direction of the optical axis of the optical unit is the front direction of the eye to be examined, and the ultrasonic actuator is different from the optical axis. It is characterized in that the eye to be examined is deformed by irradiating the eye with ultrasonic waves from a direction.

1 is an external view of an ultrasonic tonometer; FIG. It is a schematic diagram showing the inside of a housing. 1 is a schematic diagram showing the configuration of an ultrasonic actuator; FIG. 3 is a block diagram showing a control system; FIG. FIG. 4 is a diagram showing voltage signals applied to an ultrasonic actuator;

<Embodiment>
Embodiments according to the present disclosure will be described below. An ultrasonic tonometer (for example, an ultrasonic tonometer 1) of the present embodiment measures the intraocular pressure of an eye to be examined using ultrasonic waves. For example, the ultrasonic tonometer may measure the intraocular pressure by detecting changes in the subject's eye or the ultrasound when the subject's eye is irradiated with ultrasound. An ultrasonic tonometer, for example, includes a plurality of ultrasonic actuators (for example, ultrasonic actuator 100). The ultrasonic actuator has an ultrasonic element (for example, the ultrasonic element 110) and irradiates an eye to be examined with ultrasonic waves. Also, the plurality of ultrasonic actuators irradiate the eye to be examined with ultrasonic waves from two or more directions. This allows the ultrasonic tonometer to sufficiently deform the cornea of the subject's eye. For example, an ultrasonic tonometer can cause the cornea of an eye to be examined to undergo a predetermined deformation (for example, flattening or applanation) using ultrasonic sound pressure, acoustic radiation pressure, or acoustic flow.

The ultrasonic tonometer may further include an optical unit (for example, optical unit 200). The optical unit has, for example, an optical element (for example, the objective system 210, etc.) and optically acquires information on the subject's eye. In this case, the ultrasonic actuator may irradiate the subject's eye with ultrasonic waves from a direction different from the optical axis (for example, optical axis O1) of the optical unit. This allows the optical unit to acquire information about the subject's eye without being hindered by the ultrasonic actuator. The direction of the optical axis of the optical unit may be the front direction of the subject's eye. The front direction of the subject's eye is, for example, the direction of the optical axis or visual axis of the subject's eye.

Note that the optical unit may be an observation optical system (for example, the observation system 220) for observing the eye to be examined, or a detection optical system (for example, a deformation detection system) for detecting deformation of the cornea of the eye to be examined. 260). The ultrasonic tonometer may measure the intraocular pressure of the subject's eye based on the detection result from the detection optical system. Of course, the optical unit may be another optical system.

Note that the ultrasonic tonometer may further include a controller (for example, the controller 70). The controller may, for example, individually control the outputs of the plurality of ultrasonic actuators. Thereby, the control unit can adjust the acoustic radiation pressure or the like applied to the subject's eye from each direction by the plurality of ultrasonic actuators. Further, the control unit may adjust the deformed state of the cornea or may dent the cornea in a specified direction by individually controlling the plurality of ultrasonic actuators. For example, the controller may individually control a plurality of ultrasonic actuators to flatten a predetermined area of the cornea.

Note that the control unit may apply different currents or voltages to the plurality of ultrasonic actuators. For example, the controller may apply current values or voltage values of different magnitudes to a plurality of ultrasonic actuators. Also, the control unit may apply currents or voltages to the plurality of ultrasonic actuators at different timings.

Note that the control unit may apply burst waves to a plurality of ultrasonic actuators. For example, the control unit may apply burst waves to other ultrasonic actuators during intervals of applying burst waves to one ultrasonic actuator a plurality of times. As a result, it is possible to increase the acoustic radiation pressure by pseudo-shortening the interval between burst waves.

<Example>
Examples according to the present disclosure will be described below. The ultrasonic tonometer of the present embodiment measures the intraocular pressure of the subject's eye in a non-contact manner using, for example, ultrasonic waves. An ultrasonic tonometer measures intraocular pressure by optically or acoustically detecting, for example, a change in shape or vibration of an eye to be examined when the eye is irradiated with ultrasonic waves. For example, an ultrasonic tonometer continuously irradiates the cornea with pulse waves or burst waves, and calculates the intraocular pressure based on output information of ultrasonic waves when the cornea is deformed into a predetermined shape. The output information is, for example, ultrasonic sound pressure, acoustic radiation pressure, irradiation time (for example, elapsed time after trigger signal is input), frequency, or the like. When deforming the cornea of the subject's eye, for example, ultrasonic sound pressure, acoustic radiation pressure, or acoustic stream is used.

FIG. 1 shows the appearance of the device. The ultrasonic tonometer 1 includes, for example, a base 2, a housing 3, a face support section 4, a driving section 5, and the like. Inside the housing 3, an ultrasonic actuator 100, an optical unit 200, and the like, which will be described later, are arranged. The face support section 4 supports the face of the subject's eye. The face support part 4 is installed on the base 2, for example. The drive unit 5 moves the housing 3 with respect to the base 2 for alignment, for example.

FIG. 2 is a schematic diagram of the main configuration inside the housing. For example, an ultrasonic actuator 100 and an optical unit 200 are arranged inside the housing 3 . The ultrasonic actuator 100 and the optical unit 200 will be described in order with reference to FIG.

<Ultrasonic actuator>
The ultrasonic actuator 100 irradiates the eye E to be examined with ultrasonic waves. The ultrasonic actuator 100, for example, irradiates the cornea with ultrasonic waves to generate acoustic radiation pressure on the cornea. Acoustic radiation pressure is, for example, the force acting in the direction in which sound waves travel. The ultrasonic tonometer 1 of this embodiment uses this acoustic radiation pressure to deform the cornea. Note that the ultrasonic tonometer of this embodiment includes two ultrasonic actuators 100 . For example, the ultrasonic tonometer 1 includes an ultrasonic actuator 100a and an ultrasonic actuator 100b.

The ultrasonic actuator 100 emits ultrasonic waves from two or more directions, for example. For example, the ultrasonic actuator 100a irradiates the subject's eye with ultrasonic waves from the direction of the sound axis O7 tilted by an angle θ1 with respect to the optical axis O1 of the optical unit 200, which will be described later. Further, the ultrasonic actuator 100b irradiates the eye to be examined with ultrasonic waves from the direction of the sound axis O8 which is inclined by the angle θ2 with respect to the optical axis O1. The optical axis O1 of the optical unit 200 is arranged in the front direction of the subject's eye (for example, in the direction of the subject's eye's optical axis or visual axis). Therefore, the ultrasonic actuators 100a and 100b obliquely irradiate the subject's eye with ultrasonic waves.

The ultrasonic waves emitted from the ultrasonic actuator 100a travel in the direction of the sound axis O7 and generate acoustic radiation pressure in the direction of the sound axis O7. Similarly, the ultrasonic waves emitted from the ultrasonic actuator 100b travel in the direction of the sound axis O8 and generate acoustic radiation pressure in the direction of the sound axis O8. A combined pressure of the acoustic radiation pressure generated by the ultrasonic actuator 100a and the acoustic radiation pressure generated by the ultrasonic actuator 100b is applied to the eye to be examined. For example, the acoustic radiation pressure in the direction of the sound axis O7 and the acoustic radiation pressure in the direction of the sound axis O8 are combined, and pressure in the direction of the optical axis O1 is applied to the eye to be examined. As a result, the eye to be examined is pushed in the direction of the optical axis O1, and the cornea of the eye to be examined is deformed.

In this embodiment, the two ultrasonic actuators 100 a and 100 b are arranged symmetrically with respect to the optical axis O 1 of the optical unit 200 . Therefore, the angles θ1 and θ2 are the same, and the distances from the subject's eye to the ultrasonic actuators 100a and 100b are the same. This facilitates adjustment of the combined pressure produced by ultrasonic waves emitted from two directions. Of course, the ultrasonic actuators 100a and 100b do not have to be arranged symmetrically with respect to the optical axis O1. That is, the magnitudes of the angles θ1 and θ2 may not match, and the distances of the ultrasonic actuators 100a and 100b to the subject's eye may not match.

FIG. 3 is a schematic diagram of the ultrasonic actuator 100. As shown in FIG. The ultrasonic actuator 100 of this embodiment is a so-called Langevin transducer. The ultrasonic actuator 100 includes, for example, an ultrasonic element 110, an electrode 120, a mass member 130, a tightening member 160, and the like. The ultrasonic element 110 generates ultrasonic waves. The ultrasonic element 110 may be a voltage element (eg, piezoelectric ceramics), a magnetostrictive element, or the like. The ultrasonic element 110 of this embodiment is ring-shaped. For example, the ultrasonic element 110 may be a stack of piezoelectric elements. In this embodiment, the ultrasonic element 110 uses two laminated piezoelectric elements (for example, the piezoelectric element 111 and the piezoelectric element 112). For example, electrodes 120 (electrodes 121 and 122) are connected to the two piezoelectric elements, respectively. The electrodes 121 and 122 of this embodiment are ring-shaped, for example.

The mass members 130 sandwich the ultrasonic element 110, for example. By sandwiching the ultrasonic element 110 between the mass members 130, for example, the tensile strength of the ultrasonic element 110 is strengthened so that it can withstand strong vibrations. This makes it possible to generate high-power ultrasonic waves. Mass member 130 may be, for example, a metal block. For example, the mass member 130 includes a sonotrode (also called horn or front mass) 131, a back mass 132, and the like.

The sonotrode 131 is a mass member arranged in front of the ultrasonic element 110 (on the subject's eye side). The sonotrode 131 propagates the ultrasonic waves generated by the ultrasonic element 110 into the air. The sonotrode 131 of this embodiment is cylindrical. A female screw portion 133 is formed in a part of the inner circular portion of the sonotrode 131 . The female threaded portion 133 is screwed with a male threaded portion 161 formed on a tightening member 160 which will be described later. Note that the sonotrode 131 may have a shape that converges ultrasonic waves. For example, sonotrode 131 may be a cylinder with a non-uniform thickness. For example, the sonotrode 131 may have a shape in which the outer diameter changes in the longitudinal direction of the cylinder.

The back mass 132 is a mass member arranged behind the ultrasonic element 110 . The back mass 132 sandwiches the ultrasonic element 110 together with the sonotrode 131 . The back mass 132 is, for example, cylindrical. An inner circular portion of the back mass 132 is partially formed with a female screw portion 134 . The female threaded portion 134 is screwed with a male threaded portion 161 of a tightening member 160 which will be described later.

The tightening member 160 tightens, for example, the mass member 130 and the ultrasonic element 110 sandwiched between the mass members 130 . The tightening member 160 is, for example, a bolt. The tightening member 160 is, for example, cylindrical, and has a male screw portion 161 on its outer circular portion. A male threaded portion 161 of the tightening member 160 is screwed with female threaded portions 133 and 134 formed inside the sonotrode 131 and the back mass 132 . The sonotrode 131 and the back mass 132 are tightened by a tightening member 160 in a direction to attract each other. As a result, the ultrasonic element 110 sandwiched between the sonotrode 131 and the back mass 132 is clamped and pressure is applied.

<Optical unit>
The optical unit 200 performs, for example, observation or measurement of the subject's eye. The optical unit 200 includes, for example, an objective system 210, an observation system 220, a fixation target projection system 230, an index projection system 250, a deformation detection system 260, a dichroic mirror 201, a beam splitter 202, a beam splitter 203, a beam splitter 204, and the like. .

The objective system 210 is, for example, an optical system for taking light from outside the housing 3 into the optical unit 200 or irradiating the light from the optical unit 200 to the outside of the housing 3 . Objective 210 comprises, for example, an optical element. The objective system 210 may comprise optical elements (objective lens, relay lens, etc.).

The illumination optical system 240 illuminates the subject's eye. The illumination optical system 240 illuminates the subject's eye with infrared light, for example. The illumination optical system 240 includes, for example, an illumination light source 241 . The illumination light source 241 is arranged, for example, obliquely in front of the subject's eye. The illumination light source 241 emits infrared light, for example. The illumination optical system 240 may include multiple illumination light sources 241 .

The observation system 220 captures, for example, an observation image of the subject's eye. The observation system 220 captures, for example, an anterior segment image of the subject's eye. The observation system 220 includes, for example, a light receiving lens 221, a light receiving element 222, and the like. The observation system 220 receives, for example, light from the illumination light source 241 reflected by the subject's eye. The observation system receives, for example, a reflected light flux from the subject's eye centered on the optical axis O1. For example, reflected light from the subject's eye passes between the two ultrasonic actuators 100 a and 100 b and is received by the light receiving element 222 via the objective system 210 and the light receiving lens 221 .

The fixation target projection system 230 projects a fixation target onto the subject's eye, for example. The fixation target projection system 230 includes, for example, a target light source 231, a diaphragm 232, a projection lens 233, a diaphragm 234, and the like. Light from the target light source 231 passes through the diaphragm 232 , the projection lens 233 , the diaphragm 232 , etc. along the optical axis O 2 and is reflected by the dichroic mirror 201 . The dichroic mirror 201, for example, makes the optical axis O2 of the fixation target projection system 230 coaxial with the optical axis O1. The light from the target light source 231 reflected by the dichroic mirror 201 passes through the objective system 210 along the optical axis O1 and irradiates the subject's eye. The visual target of the fixation target projection system 230 is fixed by the subject, thereby stabilizing the line of sight of the subject.

The index projection system 250 projects an index onto the subject's eye, for example. The index projection system 250 projects an index for XY alignment onto the eye to be examined. The index projection system 250 includes, for example, an index light source (eg, an infrared light source) 251, an aperture 252, a projection lens 253, and the like. Light from the index light source 251 passes through the diaphragm 252 and the projection lens 253 along the optical axis O3 and is reflected by the beam splitter 202 . The beam splitter 202, for example, makes the optical axis O3 of the target projection system 250 coaxial with the optical axis O1. The light from the index light source 251 reflected by the beam splitter 202 passes through the objective system 210 along the optical axis O1 and is irradiated onto the eye to be examined. The light from the index light source 251 irradiated to the eye to be inspected is reflected by the eye to be inspected, passes through the objective system 210 and the light receiving lens 221 and the like along the optical axis O1 again, and is received by the light receiving element 222 . The indices received by the light receiving elements are used for XY alignment, for example. In this case, for example, index projection system 250 and observation system 220 function as XY alignment detection means.

The deformation detection system 260 detects, for example, the corneal shape of the subject's eye. The deformation detection system 260 detects, for example, deformation of the cornea of the subject's eye. The deformation detection system 260 includes, for example, a light receiving lens 261, an aperture 262, a light receiving element 263, and the like. The deformation detection system 260 may detect deformation of the cornea, for example, based on corneal reflected light received by the light receiving element 263 . For example, the deformation detection system 260 may detect the deformation of the cornea by receiving the light from the index light source 251 reflected by the cornea of the subject's eye with the light receiving element 263 . In this case, index projection system 250 also functions as a projection system for deformation detection system 260 . For example, corneal reflected light passes through objective 210 along optical axis O1 and is reflected by beam splitter 202 and beam splitter 203 . The corneal reflected light passes through the light receiving lens 261 and the diaphragm 262 along the optical axis O4 and is received by the light receiving element 263 .

The deformation detection system 260 may detect the deformed state of the cornea based on the magnitude of the light receiving signal of the light receiving element 236, for example. For example, the deformation detection system 260 may detect that the cornea has become applanated when the amount of light received by the light receiving element 236 reaches its maximum. In this case, for example, the deformation detection system 260 is set so that the amount of light received becomes maximum when the cornea of the subject's eye is in an applanation state.

The deformation detection system 260 may be an anterior segment cross-sectional imaging unit such as an OCT or Scheimpflug camera. For example, the deformation detection system 260 may detect the amount or speed of deformation of the cornea.

The corneal thickness measurement system 270 measures, for example, the corneal thickness of the subject's eye. The corneal thickness measurement system 270 may include, for example, a light source 271, a projection lens 272, an aperture 273, a light receiving lens 274, a light receiving element 275, and the like. Light from the light source 271 passes through, for example, the projection lens 272 and the diaphragm 273 along the optical axis O5, and is irradiated to the subject's eye. Reflected light reflected by the subject's eye is condensed by the light receiving lens 274 along the optical axis O6 and received by the light receiving element 275 .

The Z alignment detection system 280 detects, for example, the alignment state in the Z direction. The Z alignment detection system 280 has a light receiving element 281, for example. The Z alignment detection system 280 may detect the alignment state in the Z direction, for example, by detecting reflected light from the cornea. For example, the Z alignment detection system may receive light reflected by the cornea of the subject's eye from the light source 271 . In this case, the Z alignment detection system 280 may receive, for example, a bright spot formed by the light from the light source 271 being reflected by the cornea of the subject's eye. Thus, the light source 271 may also be used as a light source for Z alignment detection. For example, light from light source 271 reflected by the cornea is reflected by beam splitter 204 along optical axis O6 and received by light receiving element 281 .

<Control section>
Next, the configuration of the control system will be described with reference to FIG. The control unit 70 performs, for example, control of the entire apparatus, arithmetic processing of measured values, and the like. The control unit 70 is implemented by, for example, a general CPU (Central Processing Unit) 71, ROM 72, RAM 73, and the like. The ROM 72 stores various programs for controlling the operation of the ultrasonic tonometer 1, initial values, and the like. The RAM 73 temporarily stores various information. Note that the controller 70 may be configured by one controller or a plurality of controllers (that is, a plurality of processors). The control section 70 may be connected to, for example, the drive section 5, the storage section 74, the display section 75, the operation section 76, the ultrasonic actuator 100, the optical unit 200, and the like.

The storage unit 74 is a non-transitory storage medium that can retain stored content even when the supply of power is interrupted. For example, a hard disk drive, a flash ROM, a removable USB memory, or the like can be used as the storage unit 74 .

The display unit 75 displays, for example, the measurement result of the subject's eye. The display unit 75 may have a touch panel function.

The operation unit 76 receives various operation instructions from the examiner. The operation unit 76 outputs an operation signal to the control unit 70 according to the input operation instruction. At least one of user interfaces such as a touch panel, a mouse, a joystick, and a keyboard may be used for the operation unit 76, for example. In addition, when the display unit 75 is a touch panel, the display unit 75 may function as the operation unit 76 .

<Control of ultrasonic actuator>
Next, control of the ultrasonic actuator 100 will be described with reference to FIG. The controller 70 of this embodiment individually controls the two ultrasonic actuators 100a and 100b. For example, the control unit 70 applies voltage signals with different waveforms to the two ultrasonic actuators 100a and 100b.

For example, the control unit 70 inputs a burst wave voltage signal as shown in FIG. 5 to the ultrasonic actuator 100 . The control unit 70 inputs the voltage signal S1 to the ultrasonic actuator 100a and inputs the voltage signal S2 to the ultrasonic actuator 100b. The voltage signal S1 is a waveform in which burst waves B1 of voltage value V1 appear continuously at intervals T1. The voltage signal S2 is a waveform in which burst waves B2 of voltage value V2 appear continuously at intervals T2. By applying continuous burst waves B1 and B2 to the ultrasonic actuator 100, the acoustic radiation pressure is gradually increased to deform the subject's eye.

The voltage signal S1 and the voltage signal S2 differ in the timing at which the burst waves B1 and B2 are applied. For example, the burst wave B2 of the voltage signal S2 is applied during the interval T1 between the burst waves B1 and B1 in the voltage signal S1, and the voltage is applied during the interval T2 between the burst waves B2 and B2 in the voltage signal S2. A burst wave B1 of the signal S1 is applied. In this manner, the control section 70 may shift the timing of applying the burst waves B1 and B2 to the respective ultrasonic actuators 100a and 100b. For example, the control unit 70 may alternately apply the burst waves B1 and B2 to the ultrasonic actuator 100a and the ultrasonic actuator 100b. In this manner, the control unit 70 may control the output of the ultrasonic waves irradiated to the subject's eye by applying the burst waves B1 and B2 to the two ultrasonic actuators 100a and 100b at different timings. For example, the control unit 70 may alternately apply burst waves B1 and B2 to the two ultrasonic actuators 100a and 100b to pseudo-shorten the interval between the burst waves and increase the acoustic radiation pressure. Of course, the control unit 70 does not have to completely separate the application timings of the burst wave B1 and the burst wave B2. For example, the control unit 70 starts applying the burst wave B2 while the burst wave B1 is being applied. You may That is, the control unit 70 may slightly shift the timing of applying the burst wave B1 and the burst wave B2.

Further, the control unit 70 may adjust the deformed state of the cornea of the subject's eye by individually controlling the ultrasonic actuator 100a and the ultrasonic actuator 100b. For example, the voltage signals S1 and S2 applied to the two ultrasonic actuators 100a and 100b may be controlled so that the cornea assumes a predetermined shape (for example, an applanation shape). Also, the control unit 70 may recess the cornea in a designated direction. For example, the control unit 70 may change the timing of applying the burst waves B1 and B2 or the magnitudes of the voltage values V1 and V2 so as to flatten the predetermined region of the cornea. Of course, in each voltage signal S1, S2, the control unit 70 may make both the application timings of the burst waves B1, B2 and the magnitudes of the voltage values V1, V2 different, or make only one of them different. good too.

<Measurement operation>
A measurement operation of the ultrasonic tonometer 1 having the configuration as described above will be described. First, the control unit 70 aligns the ultrasonic tonometer 1 with respect to the subject's eye whose face is supported by the face support unit 4 . For example, the control unit 70 detects a bright spot by the index projection system 250 from the front image of the anterior segment acquired by the light receiving element 222, and drives the driving unit 5 so that the position of the bright spot is at a predetermined position. Of course, the examiner may manually align the subject's eye using the operation unit 76 or the like while looking at the display unit 75 . When the driving unit 5 is driven, the control unit 70 determines whether or not the alignment is appropriate depending on whether the position of the bright spot in the anterior segment image is at a predetermined position.

After completing the alignment for the subject's eye E, the control unit 70 measures the corneal thickness using the corneal thickness measurement system 270 . For example, the control unit 70 calculates the corneal thickness based on the light receiving signal received by the light receiving element 275 . For example, the control unit 70 may obtain the corneal thickness from the positional relationship between the peak value of reflected light from the corneal surface and the peak value of reflected light from the back surface of the cornea, based on the received light signal. The control unit 70 stores, for example, the obtained corneal thickness in the storage unit 74 or the like.

Subsequently, the control unit 70 uses the ultrasonic actuator 100 to measure the intraocular pressure of the subject's eye. For example, the control unit 70 applies a voltage to the ultrasonic element 110 to irradiate the subject's eye E with ultrasonic waves. The control unit 70 deforms the cornea by, for example, generating acoustic radiation pressure using ultrasonic waves. Then, the control unit 70 detects the deformation state of the cornea using the deformation detection system 260 . For example, the control unit 70 detects that the cornea has deformed into a predetermined shape (applanation state or flattened state) based on the light receiving signal of the light receiving element 263 . The ultrasonic tonometer 1 can obtain sufficient ultrasonic output by using the two ultrasonic actuators 100a and 100b, and can suitably deform the cornea into a predetermined shape.

The control unit 70 calculates the intraocular pressure of the subject's eye, for example, based on the acoustic radiation pressure when the cornea of the subject's eye deforms into a predetermined shape. The acoustic radiation pressure applied to the eye to be examined has a correlation with the irradiation time of ultrasonic waves, and increases as the irradiation time of ultrasonic waves increases. Therefore, the control unit 70 obtains the acoustic radiation pressure when the cornea is deformed into a predetermined shape based on the irradiation time of the ultrasonic waves. The relationship between the acoustic radiation pressure when the cornea is deformed into a predetermined shape and the intraocular pressure of the subject's eye is obtained in advance by experiments or the like, and is stored in the storage unit 74 or the like. The control unit 70 determines the intraocular pressure of the subject's eye based on the relationship stored in the storage unit 74 and the acoustic radiation pressure when the cornea is deformed into a predetermined shape.

Of course, the intraocular pressure calculation method is not limited to the above, and various methods may be used. For example, the control unit 70 may obtain the deformation amount of the cornea using the deformation detection system 260 and obtain the intraocular pressure by multiplying the deformation amount by a conversion factor. Note that the control unit 70 may correct the intraocular pressure value calculated according to the corneal thickness stored in the storage unit 74, for example.

Note that the control unit 70 may measure intraocular pressure based on ultrasonic waves reflected by the subject's eye. For example, the intraocular pressure may be measured based on changes in the characteristics of the ultrasonic waves reflected by the eye to be examined, or the amount of deformation of the cornea may be obtained from the ultrasonic waves reflected by the eye to be examined, and the intraocular pressure may be calculated based on the amount of deformation. may be measured.

As described above, the ultrasonic tonometer 1 of the present embodiment includes two or more ultrasonic actuators 100, and irradiates ultrasonic waves from two or more directions. It is possible to irradiate high-power ultrasonic waves. For example, irradiation of ultrasonic waves from two or more directions can generate a greater acoustic radiation pressure than when at least one ultrasonic actuator 100 is used. As a result, the ultrasonic tonometer 1 can detect deformation of the cornea due to ultrasonic waves, and can measure the intraocular pressure of the subject's eye without contact.

Further, by irradiating the subject's eye obliquely with ultrasonic waves as in this embodiment, the optical unit 200 can be provided in the front direction of the subject's eye. For example, since the observation system 220 can be provided in the front direction of the subject's eye, the subject's eye can be observed from the front direction, facilitating alignment of the apparatus.

In the above embodiment, the ultrasonic tonometer 1 has been described as having two ultrasonic actuators 100a and 100b, but the present invention is not limited to this. For example, the ultrasonic tonometer 1 may have three or more ultrasonic actuators. By including a plurality of ultrasonic actuators, the ultrasonic tonometer 1 can irradiate the subject's eye with ultrasonic waves of sufficient output.

In the above embodiment, a Langevin transducer is used as the ultrasonic actuator 100, but an ultrasonic actuator having another structure may be used.

In the above embodiment, a case in which a plurality of ultrasonic actuators are provided has been described. Since the ultrasonic actuator 100 does not need to be provided with an opening through which the optical axis of the observation system 220 passes in order to observe the subject's eye from the front, a sufficient output of ultrasonic waves can be maintained. Therefore, by providing at least one ultrasonic actuator for irradiating ultrasonic waves obliquely to the eye to be inspected, the eye to be inspected is irradiated with ultrasonic waves having an output sufficient to deform the cornea while the eye to be inspected is observed from the front direction. be able to.

REFERENCE SIGNS LIST 1 ultrasonic tonometer 2 base 3 housing 4 face support 6 supporting base 100 ultrasonic actuator 200 optical unit

Claims (5)

An ultrasonic tonometer that measures the intraocular pressure of an eye to be examined using ultrasonic waves,
A plurality of ultrasonic actuators having ultrasonic elements and irradiating the eye to be examined with ultrasonic waves,
The ultrasonic tonometer, wherein the plurality of ultrasonic actuators deform the eye by irradiating the eye with ultrasonic waves from two or more directions. further comprising an optical unit that has an optical element and optically acquires information about the eye to be examined;
2. The ultrasonic tonometer according to claim 1, wherein the ultrasonic actuator irradiates the eye to be examined with ultrasonic waves from a direction different from the optical axis of the optical unit. 3. The ultrasonic tonometer according to claim 2, wherein the direction of said optical axis is the front direction of said eye to be examined. 4. The ultrasonic tonometer according to claim 1, further comprising control means for individually controlling outputs of said plurality of ultrasonic actuators. An ultrasonic tonometer that measures the intraocular pressure of an eye to be examined using ultrasonic waves,
an optical unit that has an optical element and optically acquires information about the subject's eye;
an ultrasonic actuator that has an ultrasonic element and irradiates the eye to be examined with ultrasonic waves,
the direction of the optical axis of the optical unit is the front direction of the eye to be examined;
The ultrasonic tonometer, wherein the ultrasonic actuator deforms the eye by irradiating the eye with ultrasonic waves from a direction different from the optical axis.

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