Pressure measuring method, pressure measuring device, and tonometer

A tonometry device includes a contact device for contacting the object, means for vibrating the contact device and the object, means for applying a voltage to the vibration means, means for measuring a current flowing through the vibration means, and an information processing means. The information processing means determines two resonance points of the device and the measured object by measuring current through the system at a plurality of vibrational frequencies. The information processing means then determines the internal pressure of the object by determining that a first pressure is higher than a second pressure by determining that the first pressure has a lower measured current than the second pressure at frequencies outside of the range of frequencies between the resonance points, and that the first pressure has a higher measured current than the second pressure at frequencies within the range of frequencies between the resonance points.

RELATED APPLICATIONS

This application is the U.S. National Phase under 35 U.S.C. §371 of International Application PCT/JP2005/004916, filed Mar. 18, 2005, which was published in a non-English language, which claims priority to JP Application No. 2004-128423, filed Apr. 23, 2004.

TECHNICAL FIELD

The present invention relates to a pressure measuring method, a pressure measuring device, and a tonometer, which are particularly suitable to be applied to an intraocular pressure measuring technique used for an ophthalmological examination.

BACKGROUND ART

The following two methods are generally known as intraocular pressure measuring methods. To be specific, there are employed a method of applying a predetermined pressure to a cornea to measure an intraocular pressure based on a depression state of the cornea, which is caused by the pressure and a method of estimating an intraocular pressure by bringing a presser into contact with the cornea (i.e., contact type) or by blowing compressed air to the cornea, based on an area ratio of the cornea deformed by the air pressure.

However, in those methods, the cornea is directly stimulated, so a high level of safety is required. In addition, a person to be examined has to bear a large burden such as a necessity of local anesthesia or discomfort feeling caused by air blowing.

Therefore, in order to solve such the problems, various methods have been proposed. That is, examples of the proposals include a method of vibrating a surface of an eyeball by a sound wave and measuring an intraocular pressure based on an amplitude of the vibration, a resonance frequency of the eyeball, or a velocity of a surface wave of the eyeball (see JP 02-180241 A, U.S. Pat. No. 5,375,595, and U.S. Pat. No. 5,251,627) and a method of pressing an eyeball in a closed-eye state through the eyelid to measure an intraocular pressure (see JP 06-105811 A, JP 08-280630 A, and JP 08-322803 A).

DISCLOSURE OF THE INVENTION

Problems to be Solved by the Invention

However, the above-mentioned conventional pressure measuring methods and tonometers as devices therefor have the following problems. That is, the method of bringing the presser into direct contact with the cornea requires anesthesia or the like and causes the person to be examined to feel discomfort or pain.

The methods described in JP 02-180241 A, U.S. Pat. Nos. 5,375,595, and 5,251,627 also cause the person to be examined to feel discomfort or pain because the intraocular pressure measurement is performed in an opened-eye state. Pressure measuring devices itself are large in sizes and directly stimulate the cornea, so a high level of safety is required. Therefore, an examiner must be a doctor or a medical worker.

JP 06-105811 A, JP 08-280630 A, and JP 08-322803 A disclose methods of performing an examination under such a state that the eyelid is closed, that is, a closed-eye state. According to the findings of the inventors of the present invention, the reproducibility of results obtained by the intraocular pressure measurement using the methods is insufficient.

Therefore, there has been an increasing desire for developments of techniques capable of measuring a pressure such as an intraocular pressure without causing the person to be examined to feel discomfort or pain and of easily measuring a pressure such as an intraocular pressure by the person to be examined with high reproducibility.

Thus, an object of the present invention is to provide a pressure measuring method capable of measuring a pressure in a simple measurement manner with high reproducibility and a pressure measuring device capable of measuring an intraocular pressure by merely making slight contact with the eyelid in the case where it is applied to an intraocular pressure measuring device (tonometer), accurately measuring a pressure by a simple method without causing discomfort or pain to the person to be examined, and measuring an intraocular pressure by the person to be examined.

Means for Solving the Problems

In order to solve the above-mentioned problems involved in conventional techniques, the inventors of the present invention conducted concentrated studies. The summary will be described below.

That is, according to the findings of the inventors of the present invention, in the above-mentioned conventional techniques, a load applied to the cornea during intraocular pressure measurement causes discomfort. Therefore, the inventors of the present invention studied methods of performing the intraocular pressure measurement with the state in which the eyelid is closed without the application of load to the cornea.

As a result of the studies, the inventors of the present invention came up with the use of a vibrator. That is, as a result of various experiments and studies based thereon, the inventors of the present invention found that there is a characteristic that, while a predetermined alternating current voltage is being applied to a vibrator such as a bimorph type vibrator to continuously drive it, a current flowing through the vibrator is changed corresponding to a material which is in contact with the vibrator. As a result of further experiments and studies based on this finding, the inventors of the present invention concluded that, a value of current flowing through the vibrator is changed according to an intraocular pressure while an eyeball is vibrated by the vibrator, so the intraocular pressure can be measured by the measurement of the current value.

The present invention has been devised based on the above-mentioned studies.

That is, the present invention is characterized in that a pressure measuring device in which vibration means can be in direct or indirect contact with an object to be measured is used, a voltage is applied to the vibration means to vibrate the vibration means together with the object to be measured, a current value changed according to a vibration amplitude of the vibration means is measured, and a pressure of the object to be measured is calculated based on the measured current value.

To be specific, a first aspect of the present invention, there is provided a pressure measuring method, including:

bringing vibration means, which is connected with contact means for making contact with an object to be measured and vibrated by an application of a voltage, into contact with an object to be measured through the contact means, in which the object to be measured has a predetermined shape and a pressure is applied in an outward direction from the object to be measured;

applying a voltage to the vibration means by voltage applying means for applying an alternating current voltage to the vibration means;

measuring a current value flowing through the vibration means by measuring means for measuring the current value flowing through the vibration means; and

calculating the pressure based on the measured current value.

The first aspect of the invention, in a typical case, a resonance point of the object to be measured is calculated by information processing means based on a change in the current value which is caused by a change in vibration frequency, and the pressure based on a current value at a region of the resonance point is measured.

In the first aspect of the present invention, it is suitable to use a reference object to be measured as a reference for correcting a change in measurement value which is caused by a temperature characteristic of the vibrator, perform pressure measurement on the reference object to be measured immediately before or substantially simultaneously with pressure measurement on the object to be measured, and comparing a measurement value of the reference object to be measured with a measurement value of the object to be measured to measure a pressure of the object to be measured.

A second aspect of the present invention is provided a pressure measuring device, including:

contact means for making contact with the object to be measured, in which the object to be measured has a predetermined shape and a pressure is applied in an outward direction from the object to be measured;

vibration means which is connected with the contact means and vibrated by an application of a voltage;

voltage applying means for applying an alternating current voltage to the vibration means;

measuring means for measuring a current value flowing through the vibration means; and

information processing means for calculating a pressure value corresponding to the current value measured by the measuring means,

wherein, when the alternating current voltage is applied to the vibration means by the voltage applying means while the vibration means is in contact with the object to be measured through the contact means, the current value flowing through the vibration means is measured by the measuring means, and the pressure of the object to be measured is calculated by the information processing means.

A third aspect of the present invention is provided a tonometer, including:

contact means for making contact with an eyeball indirectly;

vibration means which is connected with the contact means and vibrated by an application of a voltage;

voltage applying means for applying an alternating current voltage to the vibration means;

measuring means for measuring a current value flowing through the vibration means; and

information processing means for calculating a pressure value corresponding to the current value measured by the measuring means, wherein, when the alternating current voltage is applied to the vibration means by the voltage applying means while the vibration means is in contact with the eyeball through the contact means, the current value flowing through the vibration means is measured by the measuring means, and the intraocular pressure of the eyeball is calculated by the information processing means.

In the second and third aspect of the inventions, in a typical case, a resonance point of the object to be measured is calculated based on a change in the measured current value which is caused by a change in vibration frequency, and a current value at a region of the resonance point is measured.

In the second and third aspect of the present inventions, in a typical case, support means is further provided outside a movable region of the contact means and a movable region of the vibration. means.

In the second and third aspect of the inventions, it is suitable to employ a structure in which pressure measurement on the reference object to be measured which a reference for correcting a change in measurement value which is caused by a temperature characteristic of the vibrator is executed immediately before pressure measurement or intraocular pressure measurement on the object to be measured and a measurement value of the reference object to be measured is compared with a measurement value of the object to be measured by the calculating means to measure the pressure of the object to be measured.

In the second and third aspect of the inventions, it is suitable to further include outputting means for outputting a result obtained by the measuring means and/or a result obtained by the calculating means. In the present invention, the contact means is typically connected with the vibration means through a holding member. It is desirable to use an elastic body such as a rubber as the holding member.

The technical idea of the present invention is not necessarily limited to a combination of those described above. Thus, technical ideas realized by an arbitrary suitable combination of the above-mentioned plural aspects of the present invention are also involved.

Effects of the Invention

As described above, according to the pressure measuring method of the present invention, the pressure of the object to be measured which has the predetermined shape and from which the pressure is applied outward can be measured with high reproducibility by a simple method.

According to each of the pressure measuring device and the tonometer of the present invention, an inner pressure for maintaining a shape of the object to be measured or an intraocular pressure can be measured by merely making slight contact with the object to be measured or the eyeball through the eyelid. Therefore, the pressure can be accurately measured by a simple method without large influence on the object to be measured.

According to the tonometer of the present invention, the intraocular pressure can be accurately measured by a simple method without influence on the eyeball. Therefore, the intraocular pressure can be accurately measured by a person to be examined with safety without causing the person to be examined to feel discomfort.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. Note that the same or corresponding portions in each of the drawings for the following embodiment are denoted by the same reference symbols.

First, a pressure measuring device according to the embodiment of the present invention will be described.FIG. 1shows the entire structure of the pressure measuring device according to this embodiment.

As shown inFIG. 1, the pressure measuring device according to the embodiment of the present invention, which is used as a tonometer, includes a measurer1for actually measuring an intraocular pressure, a piezoelectric driver2, a terminal base3, an information processing device4, and a resistor5.

The piezoelectric driver2is used to amplify an applied voltage. The terminal base3is used to concentrate input and output wirings, apply to the measurer1the voltage amplified by the piezoelectric driver2as an output, and measure a potential or voltage which is an input. Note that the piezoelectric driver2is constructed such that a voltage outputted from the terminal base3can be amplified by, for example, 15 times. The resistor5is used to cause voltage drop between both end portions of the resistor5and a resistance value thereof is, for example, 1 kΩ in this embodiment.

The information processing device4includes an information processing section and an auxiliary storage section which compose calculating means such as a personal computer having, for example, a hard disk. The information processing device4further includes a display capable of outputting a result obtained by calculation and a result obtained by measurement, serving as outputting means. In this embodiment, the personal computer is used for the information processing device4. However, each device including an information processing section capable of performing information processing such as calculation processing and a storage section can be employed and thus the information processing device4is not necessarily limited to the personal computer.

The auxiliary storage section (not shown) included in the information processing device4has an operating system (OS)4afor operating the information processing device4, serving as a base, an information storage database4b, a measurement result processing application4c, an input data analysis program4d, a calculation processing application4e, and an output side frequency change program4f, which are installed therein. The information processing device4executes various analysis processings and calculation processings based on the programs. In examples described later, measurement processing and analysis processing are executed based on the programs.

Next, the measurer1used for the pressure measuring device according to this embodiment will be described.FIG. 2shows the measurer1and FIG.3shows an example of a bimorph type vibrator used for the measurer1.

As shown inFIG. 2, the measurer1according to this embodiment has a structure for bringing a contactor14into contact with an eyelid16during intraocular pressure measurement. The measurer1includes a vibrator11serving as vibrating means, such as a bimorph type vibrator, four rubber bases12serving as elastic bodies, a case13vibratable with the vibrator11and the rubber bases12housed therein, and the contactor14for making actual contact with the eyelid16. Therefore, the vibrator11is substantially in indirect contact with an eyeball17, so the eyeball17is vibrated with the vibrator11.

The vibrator11is held on both sides by two pairs of rubber bases12, so it is located and fixed in the center of the case13. As shown inFIG. 3, the vibrator11has a structure in which a metallic plate11bis sandwiched on both sides by ceramic elements11a. The vibrator11is electrically connected with the piezoelectric driver2(not shown inFIG. 3) through a vibrator cable15.

In the measurer1having the above-mentioned structure, when a voltage is applied from an outside to the vibrator11through the vibrator cable15, the vibrator11first vibrates. Then, the vibration passes through the rubber bases12, the case13, and the contactor14, so the entire case13vibrates to transfer the vibration to the eyeball17through the contactor14and the eyelid16. That is, the measurer1in this embodiment is used to provide the vibration to the eyeball to be examined and noninvasively measure vibration of the eyeball to be examined. Note that the word “noninvasively” indicates that a member which is in direct contact with a cornea (not specifically shown) of the eyeball17is not used.

Next, a measurement principle in the case where an intraocular pressure is measured using the pressure measuring device having the above-mentioned structure will be described.

That is, as a result of experiments and concentrated studies, the inventors of the present invention found that the vibrator11provided in the measurer1has a characteristic that, while a predetermined alternating current voltage is being applied to continuously drive the vibrator, a current flowing through the vibrator is changed corresponding to a state of an object to be measured, which is in contact with the vibrator11through the contactor14. Here, experiments and studies on a bimorph type vibrator used as the vibrator11will be described below.

The vibrator11can be represented by an equivalent circuit shown inFIG. 4A. This equivalent circuit is an equivalent circuit of the vibrator11in a non-contact state. Even when the vibrator11is in contact with an arbitrary object, the same equivalent circuit can be fundamentally obtained.FIG. 4Bshows a frequency-impedance characteristic of the equivalent circuit.

As is apparent fromFIG. 4B, the vibrator11resonates in parallel and an impedance thereof is changed according to a frequency of an applied voltage. Therefore, it is apparent that, when the applied alternating current voltage is continuously maintained to a predetermined voltage, a current flowing through the vibrator11is changed according to the frequency. InFIG. 4B, fs which is one of resonance points is a mechanical resonance point of the vibrator11and fp which is the other of the resonance points is a resonance point caused by the vibrator11.

The measurer1including the vibrator11is placed on a rubber vibration isolator (not shown). Other vibrator cables and the like are set. After that, the vibrator11is irradiated with laser light at each measurement frequency to measure a vibration amplitude thereof using a laser displacement meter. The frequency of the applied voltage is set to 400 Hz to 700 Hz at intervals of 10 Hz. The measurement frequency is set to the vicinity of a resonance point determined in advance, more specifically, in a frequency range close to the resonance point.

As a result of measurement, it is found that a characteristic value and a resonance frequency are shifted according to the hardness of a material. As described above, the vibrator11resonates in parallel and the impedance thereof is changed according to the frequency of the applied voltage. That is, when the applied alternating. current voltage is continuously maintained to the predetermined voltage, the flowing current is changed according to the frequency. Therefore, this characteristic is utilized. A current flowing through the vibrator11is measured from a voltage dropped across the resistor5connected in series with the vibrator11. An intraocular pressure is calculated based on the measured current value.

To be specific, first, the measurer1is placed so as to be in contact with the eyeball17through the eyelid16. Next, an alternating current voltage is applied to the vibrator11based on the frequency change program installed in the information processing device4. When the vibrator11is vibrated by the application of the alternating current voltage, the entire measurer1vibrates. The vibration is transferred to the eyeball17through the eyelid16. When the vibration is transferred to the eyeball17, the eyeball17also generates vibration corresponding to the intraocular pressure thereof, thereby changing a vibration amplitude of the measurer1. Therefore, the amplitude of the vibrator11changes and the current flowing through the vibrator11is changed by a change in amplitude thereof.

Then, potentials at both ends of the resistor5are measured and the measured potential values are inputted to the information processing device4. The information processing device4performs calculation processing on the potential values based on the calculation processing application to obtain a difference therebetween, that is, a voltage. Therefore, a change in current flowing through the vibrator11is calculated. An intraocular pressure value is calculated based on the current value by the information processing device4. Because the information processing device4includes the display serving as the outputting means, when the change in current is calculated, a result obtained by analysis processing using the analysis program is displayed on the display.

Hereinafter, although specific methods of embodying the present invention will be described with reference to examples, the present invention is not limited to those.

A rubber balloon filled with water, which is a model of the eyeball, is attached to an end of a cylindrical glass tube. The cylindrical glass tube is fixed to a support base. The contactor14of the measurer1is made in contact with the balloon and water is slowly injected to the glass tube to change an inner pressure of the balloon. At this time, a level increased from an interface portion between the balloon and the glass tube by 1 cm is set as a reference. A level of the water is increased from the reference to 5 cm, 10 cm, and 15 cm at intervals of 5 cm to change the inner pressure of the balloon.FIG. 5shows a frequency characteristic of a result obtained by measurement.FIG. 5Bis an enlarged graph showing the region of resonance points in a frequency range shown inFIG. 5A.

As is apparent fromFIG. 5, when the measurer1is made in contact with the rubber balloon to perform measurement, a current characteristic can be obtained in order of pressure and the resonance points of the vibrator11exist in a frequency region of 700 Hz to 850 Hz. As is also apparent from the figure, the current characteristic reduces with an increase in pressure in a frequency range outside the frequency region between the two resonance points. In contrast to this, the current characteristic increases with an increase in pressure in the frequency region between the two resonance points. That is, as is apparent from that, in the case of a mechanical resonance, the current reduces with an increase in inner pressure of the balloon. In the case of a resonance based on an electrical capacitance, the current increases with an increase in pressure. As is apparent from that, when the inner pressure is changed, a changed pressure can be determined using the measurer1.

Next, a frequency-current characteristic of an eyeball with an eyelid, of a pig (pig eye with eyelid) in the case where an inner pressure of the eyeball thereof is changed is measured. An intraocular pressure changing method to be employed is a method of inserting an injection needle from optic nerves of the pig eye, connecting the injection needle with a container containing a normal saline solution, and moving the container upward and downward with a state in which a water surface level of the container is made substantially equal to a level of the pig eye, thereby changing an intraocular pressure of the pig. Then, the eyelid of the pig eye with eyelid is opened and the measurer1is made in direct contact with the eyeball. The measurement is performed in a frequency region of 700 Hz to 850 Hz. After that, the eyelid is closed and the same measurement is performed in contact with the eyelid. A series of measurement described above is repeated while the intraocular pressure is changed.

Results obtained by frequency-current characteristic measurement as described above are shown inFIGS. 6 and 7.FIG. 6shows a result obtained by measurement in the case where the measurer1is made in direct contact with the eyeball.FIG. 7shows a result obtained by measurement in the case where the measurer1is made in contact with the eyelid with a state in which the eyelid is closed.FIGS. 6B and 7Bare enlarged graphs showing the regions of resonance points in frequency ranges shown inFIGS. 6A and 7A.

As is apparent fromFIGS. 6 and 7, a current characteristic can be obtained in order of pressure by measurement in each of the case where the measurer1is made in contact with the eyeball and the case where the measurer1is made in contact with the eyelid. In addition, a result in the case of the measurer1being in contact with the eyeball is very similar to that in the case of the measurer1being in contact with the eyelid.

Based on the results,FIG. 8shows a comparison between the result ofFIG. 6and the result ofFIG. 7with respect to the dependence of current value on pressure at a frequency point of 769 Hz (which is an intermediate point between a local maximum point and a local minimum point (i.e., two resonance points)).

As is apparent fromFIG. 8, although current shift is caused between the case where the measurer1is made in contact with the eyeball and the case where the measurer1is made in contact with the eyelid, similar characteristics are obtained. Therefore, it is apparent that the influence of the eyelid16is small in the case where the measurer1is used in this embodiment.

In the course of the measurement on the pig eye, the inventors of the present invention found that the vibrator11of the measurer1has temperature characteristics and a current is varied thereby. Then, the inventors of the present invention devised a method of performing measurement after the vibrator11continuously vibrates until a temperature thereof saturates. Therefore, stable intraocular pressure measurement can be performed.

This method is employed and current characteristic measurement on the same person to be examined is performed successively using the measurer1. That is, the vibrator11is vibrated for 45 minutes. Immediately after the temperature of the vibrator11saturates, the measurer1in this embodiment is made in contact with the eyelid of a human and the current characteristic measurement is performed 10 times at intervals of 2 minutes. A frequency region for current characteristic measurement is set to 700 Hz to 840 Hz. The measurer1is separated from the eyelid16for each measurement.FIG. 9shows a result obtained by the measurement.FIG. 9Bis an enlarged graph showing the region of resonance points in a frequency range shown inFIG. 9A.

As is apparent fromFIG. 9, a current increases with an increase in the number of measurement in a frequency range outside the frequency region between two resonance points. As is already apparent from the result in Example 1 as described above, the increase in current in the frequency range outside the frequency region between the two resonance points is equivalent to a reduction in measured pressure. Therefore, it is apparent that the intraocular pressure is changed by the repetition of measurement.

The method of vibrating the vibrator11until the temperature thereof saturates, which is employed for the above-mentioned current characteristic measurement, takes time. The reason is that the vibrator11has the temperature characteristic. Then, as a result of study of a method of minimizing the influence of the temperature characteristic, the inventors of the present invention devised a method of performing calibration using a reference base.FIG. 10shows a calibration procedure using the reference base.

As shown inFIG. 10, a reference base21is made of, for example, rubber and is provided on an elastic spring22having the same elasticity as that in the case where the eyeball is pressed. The contactor14of the measurer1is made in contact with an upper portion of the reference base21to perform measurement. Immediately after that, the contactor14of the measurer1is made in contact with the eyelid16to measure an intraocular pressure. That is, measurement on the reference base21for which a predetermined pressure is continuously maintained and measurement on an eyeball to be examined which is an object to be measured are substantially simultaneously performed. To be specific, the measurements are successively performed in tandem. Therefore, a value measured in contact with the eyelid to perform analysis for obtaining the intraocular pressure is calibrated based on a value measured using the reference base21to improve the precision of measurement.

To be specific, a gain a of α value “y” obtained in the case of contact with the eyelid relative to a value “x” obtained in the case where the contactor14is made in contact with the reference base21, at each frequency is calculated using the following expression (1).
α=y/x  (1)

The gain α in the expression (1) is a ratio between a predetermined pressure continuously applied to the reference base21and a measured pressure from the eyelid16. The pressure applied to the reference base21is maintained constant, so the measured pressure becomes constant. Therefore, an intraocular pressure value measured from the eyelid16can be accurately obtained based on the gain α. The measurement on the reference base21and the measurement on the eyelid16are substantially simultaneously performed, so the influence of the temperature characteristic can be minimized.

The inventors of the present invention conducted intraocular pressure measurement with a state in which the measurer1in this embodiment is made in contact with the eyelid of a human based on the above-mentioned calibration. The inventors of the present invention conducted intraocular pressure measurement on the eyeball of the human using a conventional air puff type tonometer, as a comparative example.FIG. 11shows a result obtained by the measurement. As shown inFIG. 11, a measurement number in the case where the measurer1is used is shifted by one from a measurement number in the case where the conventional air puff type tonometer is used. This is to meet a change in intraocular pressure which is caused by the successive measurements, which is determined in

As is apparent fromFIG. 11, a change intraocular pressure in the intraocular pressure measurement using the measurer1in this embodiment follows that in the measurement using the conventional air puff type tonometer, so substantially the same results are obtained.

From the above-mentioned examples, the inventors of the present invention found that, in order to use the measurer1in this embodiment for a tonometer in which reproducibility is further improved, it is necessary to bring the measurer1into contact with the eyelid of a human in the same condition for each contact. However, when the contactor14of the measurer1is to be made in contact with the eyelid of the human to perform the measurement, it is difficult to place the case13of the measurer1on the eyelid of the human. Then, as a result of study, the inventors of the present invention devised to provide a support base for supporting the case13of the measurer1.FIGS. 12 and 13show a structure of the measurer1provided with the support base.

As shown inFIGS. 12 and 13, a support base23supports the case13and has a concave curve-shaped portion close to a skeletal shape of the vicinity of an eye of the human, which is provided therein. In this embodiment, the support base23is formed such that a side shown inFIG. 12corresponds to the left side or the right side of the face of the human. In addition, the support base23is formed such that a left side shown inFIG. 13corresponds to a nose side relative to the eye and a right side shown therein corresponds to a temple side relative to the eye. Therefore, the support base23is constructed to support the measurer1and cover the vicinity of the eye in the face of the human. When the concave curve-shaped portion of the support base23is made in contact with the vicinity of the eyeball of the human, the contactor14is in contact with the eyelid16. In order to prevent the support base23from influencing the intraocular pressure measurement, the support base23is held in the outside of the case13and attached to a portion which is located outside a movable region (i.e., vibration region) of the contactor11and does not hinder the vibration.

Therefore, when a user of the measurer1holds the support base23to measure the intraocular pressure, there is no case where a hand of the user is contact with the contactor14, the case13housing the vibrator11, or the like during vibration. Thus, the measurement using the measurer1is not influenced. The contactor14is relatively held to the support base23, so it is possible to bring the contactor14into contact with the eyelid of the human constantly in the same condition.

The embodiment of the present invention and the examples thereof are specifically described. However, the present invention is not limited to the above-mentioned embodiment and thus various modifications based on the technical idea of the present invention can be made.

For example, numerical values described in this embodiment are merely examples and different numerical values may be used if necessary.

For example, in the above-mentioned embodiment, the bimorph type vibrator is employed as the vibrator for the measurer1. Any vibrator in which a current value is changed according to the amplitude of the vibration can be employed as such a vibrator. For example, a piezoelectric ceramic vibrator such as a Langevin type vibrator can be employed.

In the above-mentioned embodiment, the elastic rubber which is the elastic body is used as a holding member for holding the vibrator11in the case13. However, an elastic spring or a synthetic resin can be also used, for example. Other materials capable of holding the vibrator by a suitable force also can be used.

Further, for example, in order to generate a larger vibration in the vibrator11provided in the measurer1in the above-mentioned embodiment, a weight made of, for example, brass, stainless steel, or metal such as lead (Pb) or copper (Cu) may be further provided in the vibrator11. The weight can be provided in an arbitrary portion of the vibrator11. In view of the stability of vibration, it is desirable to provide the weight in a center portion of the vibrator11on a surface perpendicular to a vibration amplitude direction thereof.

Description of Symbols

4information processing device

4binformation storage database

4cmeasurement result processing application

4dinput data analysis program

4ecalculation processing application

4foutput side frequency change program