JPH08108B2 - Non-contact tonometer - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-contact tonometer which discharges air to the cornea of an eye to detect the intraocular pressure of the eye.

[0002]

2. Description of the Related Art Conventionally, a non-contact tonometer is known which is provided with an air discharge means for discharging air from a nozzle portion toward a cornea of an eye to be examined by a piston movable in a cylinder. In this non-contact tonometer, the air whose pressure changes with time is discharged toward the cornea of the eye to be inspected, but it is also possible not to release air of an excessively high pressure to the cornea of the eye to be inspected. is necessary. for that reason,
It has also been proposed to stop the piston by interrupting a solenoid current for controlling the movement of the piston when the cornea of the eye to be examined is deformed by a predetermined amount.

[0003]

By the way, in this conventional non-contact tonometer, even if the solenoid current is cut off, the inertia of the piston is large and the piston moves thereafter. It is inevitable that pressure will be applied.

The present invention has been made in view of the above problems of the prior art. An object of the present invention is to accelerate the relaxation of the air flow pressure after a predetermined deformation of the cornea, and to increase the air pressure more than necessary. Therefore, it is to provide a non-contact tonometer that can reduce the burden on the subject.

[0005]

In order to solve the above-mentioned problems, the non-contact tonometer according to the present invention has a structure in which pressure is applied from the nozzle portion to the cornea of the eye to be examined with time by a piston capable of moving forward and backward in the cylinder. In a non-contact tonometer having an air releasing means for releasing changing air and a corneal deformation detecting means for detecting deformation of the cornea of the eye to be inspected, a valve for releasing air in a cylinder, and the corneal deformation A valve drive control unit for detecting that the cornea of the eye to be inspected has undergone a predetermined deformation based on a signal from the detection means and opening the valve based on the detection signal is provided.

[0006]

According to the non-contact tonometer according to the present invention, the air discharging means discharges the air whose pressure changes with time from the nozzle portion to the cornea of the eye to be inspected by the piston that can move forward and backward in the cylinder. The corneal deformation detecting means detects the deformation of the cornea based on the release of the air. The valve drive control unit opens the valve based on the signal from the corneal deformation detecting means. The pressure in the cylinder is reduced by opening the valve after the cornea has undergone a predetermined deformation.

[0007]

1 shows a first embodiment of a non-contact tonometer according to the present invention. In FIG. 1, 1 is a fluid discharging means, 2 is a cornea of an eye to be examined, 3 is an ejection optical system, 4 Is a detection optical system. The fluid discharge means 1 is for discharging a fluid to the cornea 2 in order to deform the cornea 2 of the eye to be examined (hereinafter referred to as the cornea).

The fluid discharge means 1 is generally composed of a rotary solenoid 5, a cylinder 6 and a rotary solenoid drive circuit 7, and 8 is a drum of the rotary solenoid 5. The cylinder 6 has a cylinder tubular portion 9, a nozzle tubular portion 10, and a sensing tubular portion 11. A piston 12 is provided in the cylinder tube portion 9 so as to be capable of reciprocating, and the piston 12 is connected to the drum 8 of the rotary solenoid 5 via a piston rod 13. The nozzle cylinder 10 is designed to extend straight toward the cornea 2, and the fluid is discharged from the nozzle cylinder 10 by the reciprocating motion of the piston 12. The on / off conditions of the rotary solenoid drive circuit 7 will be described later. The sensing cylinder portion 11 extends from the peripheral wall of the cylinder cylinder portion 9, and a pressure sensor element described later is attached to the sensing cylinder portion 11.

The cornea 2 is deformed on the basis of the fluid pressure of the fluid, and is deformed from the convex state to the planar state to the concave state with the increase of the fluid pressure of the fluid.
Shows a state in which the cornea 2 is deformed. Reference numeral m is shows the amount of deformation, the deformation amount m is, O ₂ vertices of the cornea 2 before undergoing deformation exists on the center line O ₁ of the cornea 2, the upper center line O ₁ of the cornea 2 When the apex of the cornea C existing in the body and undergoing deformation is O ₃ , the apex O ₂ and the apex O ₃
It refers to the distance from.

The emission optical system 3 and the detection optical system 4 constitute a physical quantity corneal reflected light quantity detecting means for indicating corneal deformation, which photoelectrically detects the deformation amount m of the cornea 2. Ejection optical system 3
Is composed of a light source 14, a condenser lens 15, a diaphragm 16 and a light projecting lens 17, and O ₄ is an optical axis of the emission optical system 3. The diaphragm 16 is provided so as to be at the focal position of the lens 17, and the light emitted from the light source 14 is emitted to the cornea 2 through the condenser lens 15, the diaphragm 16 and the light projecting lens 17 as detection light composed of parallel light beams. It has become so. Detection optical system 4
Is composed of an imaging lens 18, a diaphragm 19, and a photoelectric conversion circuit 20, and the photoelectric conversion circuit 20 includes a light receiving element 21 and an amplification circuit 22.
It consists of and.

The detection light emitted from the emission optical system 3 and passing through the cornea 2 is received by the light receiving element 21 via the imaging lens 18 and the diaphragm 19 and photoelectrically converted, and the amplification circuit 22.
Through, a cornea deformation amount corresponding signal corresponding to the deformation amount m of the cornea 2 is output.

Reference numeral 23 is a corresponding pressure detecting circuit as corresponding pressure detecting means. The corresponding pressure detecting circuit 23 is composed of a pressure sensor element 23a and an amplifying circuit 25. The pressure sensor element 23a is the sensing tube portion 1 of the cylinder 6 as described above.
This pressure sensor element 23a is mounted on 1, and detects the fluid pressure of the fluid guided to the sensing tubular portion 11 corresponding to the fluid pressure of the fluid guided and discharged to the nozzle tubular portion 10. The detection signal is output as a corresponding pressure detection signal through the amplifier circuit 25.

Reference numeral 24 is a measuring circuit as an intraocular pressure value converting means. The measuring circuit 24 deforms the cornea 2 based on information contained in detection signals output from the photoelectric conversion circuit 20 and the corresponding pressure detection circuit 23. A correlation function curve between the amount of detected light corresponding to the amount m and the corresponding pressure of the fluid is established, and the value of the corresponding pressure corresponding to the preset value of the deformation amount m of the cornea 2 is determined from this correlation function curve. It has a function of converting the calculated corresponding pressure value into an intraocular pressure value, and its circuit configuration will be described with reference to FIG.

As shown in FIG. 2, the measuring circuit 24 includes a central processing circuit (hereinafter abbreviated as CPU) 25 and a memory circuit 26.
And a changeover switch circuit 27. The CPU 25 is the center of the measuring circuit 24.
It will be described in relation to other circuit components. The changeover switch circuit 27 is conceptually shown in FIG. 2 as a contact switch, and here is provided with three changeover switches 28, 29, 30 and each changeover switch 28, 29, 30 is provided. Is 2
It is supposed to have two switching contacts A and B.

In addition to this, the measuring circuit 24 has two sampling circuit systems for sampling data for establishing a correlation function curve. One sampling circuit system includes a sample and hold circuit 31, an adding circuit 32, a reference voltage generating circuit 33, a comparing circuit 34, a pulse generating circuit 35, an address counter circuit 36, and an OR circuit 37. .

A corresponding pressure detection signal from the corresponding pressure detection circuit 23 is input to the sample and hold circuit 31, and the sample and hold circuit 31 has a control terminal and a pulse is applied to this control terminal. When a signal is input, the voltage value of the corresponding pressure detection voltage at that time is sampled, and this voltage value is held until the pulse signal is next input to the control terminal.

The adding circuit 32 adds the voltage values of the sample-and-hold circuit 31 and the reference voltage generating circuit 33,
The voltage of the added voltage value is output. Comparison circuit
The output voltage of the addition circuit 32 is input to the positive terminal of the 34 and the corresponding pressure detection voltage is input to the negative terminal of the comparison circuit 34.
When the output voltage is higher than the output voltage, the output becomes high level. When the output of the comparison circuit 34 becomes high level, the pulse generation circuit 35 outputs a single pulse signal.
Is composed of, for example, a monostable multivibrator.

The address counter circuit 36 counts the pulse signals of the pulse generating circuit 35, and outputs the count value, address information, through the changeover switch 30 to the memory circuit 26.
It is supposed to be transmitted to. The pulse signal of the pulse generation circuit 35 is also input to the control terminal of the sample and hold circuit 31 through the OR circuit 37, and the pulse signal is input from the CPU 25 to the OR circuit 37. ing.

That is, this sampling circuit system increments the address counter circuit 36 at every step of a predetermined pressure in the process of increasing the corresponding pressure, and the output thereof corresponds to the corresponding pressure data and is obtained as address information. Is. The other sampling circuit system is composed of a sample-and-hold circuit 38 and an analog-digital conversion circuit 39.

The sample-and-hold circuit 38 receives a corneal reflected light detection signal corresponding to the amount of corneal deformation from the photoelectric conversion circuit 20, and the sample-and-hold circuit 38 has a control terminal. When a pulse signal is input to this control terminal, the voltage value of the corneal reflected light amount detection signal at that time is sampled, and this voltage value is held until the pulse signal is input to the control terminal next time.

The voltage value held by the sample and hold circuit 38 is the analog digital conversion circuit.
It is converted into a digital amount by 39 and input to the memory circuit 26 via the changeover switch 29. The input of the pulse signal to the control terminal of the sample-and-hold circuit 38 is performed from the OR circuit 37.
Therefore, in this sampling circuit system, at the same time as the corresponding pressure data is updated, the light amount data corresponding to the corresponding pressure data is sampled.

The measuring circuit 24 further includes a circuit system for stopping the rotary solenoid 5. This circuit system is composed of a comparison circuit 40, a reference voltage generation circuit 41, and a pulse generator 42. That is, the comparison circuit 40, the reference voltage generation circuit 41, the pulse generator 42 constitutes a control means for weakening the pressing force of the fluid discharge means based on the signal from the corneal deformation detection means, and the comparison circuit 40 has a positive terminal. The output voltage from the reference voltage generation circuit 41 is input, and the corneal reflected light amount detection signal from the photoelectric conversion circuit 20 is input to the negative terminal.

The output voltage of the reference voltage generating circuit 41 is set to the voltage of the corneal reflected light amount detection signal from the photoelectric conversion circuit 20 just before the deformation amount m of the cornea 2 becomes maximum, and the comparison circuit 40 When the voltage of the corneal reflected light amount detection signal becomes equal to or higher than the output voltage of the reference voltage generation circuit 41, high level output is performed. When the output of the comparison circuit 40 changes from the high level to the low level, a single pulse signal is output from the pulse generation circuit 42, and this pulse signal is input to the rotary solenoid drive circuit 7.
The rotary solenoid drive circuit 7 stops the rotary solenoid 5 when receiving this pulse signal.

By the way, the CPU 25 is connected to a power switch, a start switch 43 and a display unit 44 which are not shown. First, when you turn on the power switch, this CPU2
A changeover switch control signal is output from 5 to the changeover switch circuit 27, the changeover switches 28, 29, 30 are set to the B contact side, and the memory circuit 26 is initialized. At the same time, a reset signal is input from the CPU 25 to the address counter 36, and the address counter 36 remains reset. Thereafter, the changeover switch control signal is output again from the CPU 25 to the changeover switch circuit 27, and the changeover switches 28, 23, 30 are set to the A contact side.

In this state, if the start switch 43 is turned on or turned on and the CPU 25 receives a switch input, the CPU 25 reads this and performs the next process. First, a pulse signal is output to the OR circuit 37, and the sample and hold circuits 31 and 38 are made to sample and hold the voltage of the corresponding pressure detection signal and the voltage of the corneal reflected light amount detection signal at the present time. At the same time, the current pressure data and light intensity data are stored in the memory circuit 26.
To be stored. At this point in time, the fluid has not been discharged and the cornea 2 has not been deformed accordingly, so both voltages are 0 V, and the comparison circuit 34 has 0 V at its negative terminal.
Since the reference voltage generating circuit 33 is activated at the same time that the power switch is turned on, the output voltage is applied to the positive terminal, so that the output of the comparison circuit 34 is at a low level. After that, the reset of the address counter 36 is released, and a drive control signal is input to the rotary solenoid drive circuit 7 to start the operation of the rotary solenoid 5.

After the operation of the rotary solenoid 5 is started, the light amount data corresponding to the corneal deformation amount with respect to the corresponding pressure data obtained at the step of the predetermined pressure is sampled by the two sampling circuit systems, and the sampling data is stored in the memory. It is stored in the circuit 26 at every sampling. That is, the memory circuit 26 functions as a storage unit that stores the pressure information and the corneal deformation information for each predetermined step corresponding to each other based on the outputs of the pressure detection unit and the corneal deformation detection unit.

In this process, when the output of the comparison circuit 40 changes from high level to low level, the rotary solenoid 5
Is stopped, and the increase in fluid pressure stops. Along with this, the voltage of the corresponding pressure detection signal stops increasing, and thereafter the output of the comparison circuit 34 remains at the low level, so that data sampling is not performed.

Thereafter, after a lapse of a predetermined time by the timer of the CPU 25, a changeover switch control signal is input from the CPU 25 toward the changeover switch circuit 27, and the changeover switch is inputted.
28, 29, 30 are set on the B contact side. Then, the CPU 25 reads the sampling data in the memory circuit 26, and establishes a correlation function between the corresponding pressure P and the light amount L of the detected light corresponding to the corneal deformation amount m as shown in FIG. 3 based on the sampling data. In FIG. 3, Pmax is the maximum value of the corresponding pressure, and Lmax is the maximum value of the light amount.

When the correlation function is established, the CPU 25 calculates the corresponding pressure corresponding to the preset light amount corresponding to the corneal deformation amount from the correlation function, and converts the calculated corresponding pressure value into the intraocular pressure value. Here, the corresponding pressure value P _l at the maximum value Lmax of the light amount L, and P _h is adapted to convert the intraocular pressure value. In FIG. 3, a solid curve H
Although the curve i and the broken line Lo are shown, these curves Hi and Lo are those of separate corneas. It goes without saying that the cornea associated with the curve Hi has a larger intraocular pressure value than the cornea associated with the curve Lo. When the CPU 25 obtains the intraocular pressure value, the intraocular pressure value is displayed on the display unit 44.

By the way, as shown in detail in FIG. 4, the cylinder 6 of this embodiment is provided with a fluid escape cylinder portion 45, and the fluid escape cylinder portion 45 is provided with an electromagnetic valve 46. The non-contact tonometer is provided with a solenoid valve drive circuit 47 that opens the solenoid valve 46 when the pulse signal of the pulse generation circuit 42 is input, so that the fluid pressure applied to the cornea 2 can be released more quickly. You can

Further, the photoelectric conversion circuit 20 and the corresponding pressure detection circuit
23 is replaced and the photoelectric conversion circuit 20 is connected to the circuit system of the sample and hold circuit 31 side, and the corresponding pressure detection circuit 23
May be connected to the circuit system on the sample and hold circuit 38 side. In this case, the correlation function is established as shown in FIG.

Next, a second embodiment of the non-contact tonometer according to the present invention will be described with reference to FIG. In addition, this Example 2
Has the same constituent elements as those of the first embodiment, the same constituent elements are designated by the same reference numerals as those of the first embodiment, and the detailed description thereof will be omitted.

In FIG. 6, the cylinder 6 of the fluid discharge means 1 is substantially T-shaped, and this cylinder 6 has nozzle cylinder parts 48, 49 in addition to the cylinder cylinder part 9. The nozzle cylinder portion 48 extends straight toward the cornea 2, and the nozzle cylinder portion 49 extends in the direction opposite to the nozzle cylinder portion 48. The pressure sensor element 24 is attached to the opening end of the nozzle tubular portion 49. The fluid flowing in the cylinder 6 due to the reciprocating motion of the piston 12 is guided to the nozzle tubular portion 48 and the nozzle tubular portion 49, and the fluid is discharged from the nozzle tubular portion 48 toward the cornea 2. is there.

The emission optical system 3 includes a light projecting lens 50 and an infrared light emitting diode 51, and an optical axis O ₄ of the light projecting lens 50.
However, the light projecting lens 50 is provided so as to be parallel to the center line axis O ₁ of the cornea 2 of the eye to be examined. The infrared light emitting diode 51 is provided so that its light emission center is located at the focal position of the light projecting lens 50, and the light projecting lens 50 uses the spot light composed of parallel light flux as the detection light through the diaphragm A ′ to form the cornea 2 It is one that shoots toward. Detection optical system 4
Includes an imaging lens 52 and a photoelectric converter 53, and the detection optical system 4 receives the detection light emitted from the emission optical system 3 and passing through the cornea 2, and photoelectrically converts the detection light. It has a function of outputting a signal corresponding to the corneal deformation of the examined eye corresponding to the amount of corneal deformation of the examined eye. The imaging lens 52 is provided so that its optical axis O ₅ intersects the optical axis O _4, and the photoelectric converter 53 is provided at the focal position of the imaging lens 52 and is reflected by the cornea 2. The detected light is focused on the photoelectric converter 53. A one-dimensional CCD linear sensor array is used for the photoelectric converter 53 here.

In FIG. 6, reference numeral P ₁ indicates the detection light reflected by the cornea 2 of the eye to be inspected before being deformed, and reference numeral P ₂ is the cornea C of the eye to be inspected when it is deformed by the deformation amount m. The reflected detection light is shown. Here, the detection light P ₁ is shown as being imaged at the r ₁ -th position of the constituent element 54 of the photoelectric converter 53, and the detection light P ₂ is the constituent element. The state of being imaged at r _{2 of} 54 is shown. The time-series output signal from the photoelectric converter 53 is detected by the detection circuit.
55 is input to the detection circuit 55.
It has a function of outputting a voltage corresponding to the address information. The output of the detection circuit 55 is configured to be input to the sample-and-hold circuit 38 and the comparison circuit 40 of the measurement circuit 24.

When the cornea 2 is deformed by the deformation amount m, the image formation position of the detection light is changed by Δr, and the change Δr of the image formation position and the deformation amount m have a correspondence relationship. This change Δr in the image forming position is grasped as a voltage difference.

That is, the corneal deformation amount data is sampled based on the output voltage of the detection circuit 55.
In this embodiment, the emission optical system is configured to use a minute spot light, but it may be configured to project a circular pattern or a grid pattern on the cornea and detect the amount of deformation.

In this embodiment, the detection optical system uses a one-dimensional change in the image forming position.
It is also possible to adopt a two-dimensional configuration that detects the area change of the circular pattern.

Further, when the subject is a corneal astigmatic eye, the position and displacement of the reflected spot light differ along the corneal meridian direction. In that case, for example, along the corneal meridian direction, A deformation detection optical system may be arranged every 60 degrees.

Next, a third embodiment of the non-contact tonometer according to the present invention will be described with reference to FIGS.

In this embodiment, the fluid discharge means 1 and the measuring circuit 24 have the same structure as in the first embodiment, and therefore their illustration is omitted. The emission optical system 3 is generally composed of a light source 56, a condenser lens 57, a slit plate 58, and a projection lens 59.
An incandescent light bulb is used as the light source 56, the light source 56 is provided at the focal position of the condenser lens 57, and the slit plate 58 is provided between the condenser lens 57 and the projection lens 59,
The slit plate 58 is provided with an elongated slit 60,
The detection light passing through the slit 60 is projected as the slit projection light 61 by the projection lens 59 toward the cornea 2 of the eye to be examined. The cornea 2 of the eye to be examined is cut by the slit projection light 61.

The detection optical system 4 has an observation microscope structure, and is roughly composed of an objective lens 62, a left eye optical system 63 and a right eye optical system 64. The left eye optical system 63 is a variable power optical system 65.
And imaging lens 66, erecting optical system 67, focusing screen 68 and eyepiece lens
The right-eye optical system 64 includes a variable power optical system 70, an imaging lens 71, an erecting optical system 72, a focusing screen 73, and an eyepiece 74, and the slit of the cornea 2 The cross section is to be observed by the measurer. In the right eye optical system 64, a half mirror 75 is provided between the variable power optical system 70 and the imaging lens 71 at an angle with respect to the optical axis of the right eye optical system 64. A part of the slit projection light reflected by the cornea 2 is reflected by the half mirror 75, and an imaging lens 76 and an area sensor 77 are provided ahead of the reflection direction.

The image forming lens 76 and the area sensor 77 are
The slit projection light flux is arranged so as to satisfy the Scheimpflug principle. The area sensor 77 has
An area CCD is used, and the area sensor 77 has at least three scanning lines. Conventional slit lamps can be used for the objective lens 62, the left-eye optical system 63, and the right-eye optical system 64, and the half mirror 75, the imaging lens 76, and the area sensor 77 are housed in a case 78, which is an optional configuration. Can be

The cross-sectional position of the cornea 2 is adjusted to a predetermined position by the measurer using the left eye optical system 63 and the right eye optical system 64. The slit projection light reflected from the cornea 2 is imaged on the area sensor 77 as a corneal cross-sectional image by the imaging lens 76. FIG. 8 shows a cross-sectional image of this cornea, and is designated by the symbol C.
Reference numeral ₁ denotes a corneal cross-sectional image before the cornea 2 is deformed, reference numeral C ₂ denotes a corneal cross-sectional image when the cornea 2 is deformed by the deformation amount Δ, and L ₁ , L ₂ , and L ₃ are The scanning lines are shown, and when the start switch is pressed, the constituent elements of the area sensor 77 are scanned by at least three scanning lines. Which constituent element forms the corneal cross-sectional image by this scanning. The image forming position in the sense of is required.

Here, three image forming positions S ₁ , S ₂ , S ₃ are obtained, and these are input to the detecting circuit 79 as an image forming position signal, and this detecting circuit 79 outputs the image forming position signal before deformation. The voltage corresponding to the address information of the element is input to the sample-and-hold circuit 38 of the measuring circuit 24. This scanning is performed at a high speed, and the image formation position changes every moment during the process of deformation of the cornea 2, and the image formation position signal in the deformation process is sent to the detection circuit 79. The voltage is input momentarily, and the output voltage from the detection circuit 79 is input to the sample and hold circuit 38.

That is, the output voltage of the detection circuit 79 is sampled as the corneal deformation amount data. Note that, in FIG. 8, reference numerals S ₁ ′, S ₂ ′ and S ₃ ′ are image forming positions when the cornea 2 is deformed by the deformation amount Δ.

By the way, as a method of measuring the intraocular pressure of the cornea 2 to be inspected, in order to remove the influence of the elastic force of the cornea itself and the ocular pressure measurement of lacrimal fluid, the cornea 2 to be inspected is circularly flat with a diameter of 3.06 mm. There is an applanation tonometry method for applanation so that when the applanation tonometry method is used, the imaging position S ₁ ″,
When S ₂ ″ and S ₃ ″ are aligned on a straight line as shown in FIG. 9, the corneal predetermined deformation position is set, and the intraocular pressure value can be obtained based on the fluid pressure at that time.

Next, a fourth embodiment of the non-contact tonometer will be described with reference to FIG.

This embodiment shows a modified example of the second embodiment, in which the nozzle tube portion 4 extends from the apex O ₂ of the cornea 2 before the deformation.
Nozzle tube portion 4 by distance D ₂ equal to distance D ₁ to the tip of 8
The pressure sensor element 23a is provided so as to be spaced from the tip of 9, and the pressure corresponding to the fluid pressure of the fluid is detected as close as possible to the fluid pressure received by the cornea 2; Since it is the same as, the description thereof will be omitted.

[0050]

[Effect] Since the present invention is configured as described above, it is possible to accelerate the relaxation of the air flow pressure after the predetermined deformation of the cornea, and to prevent the subject from being provided with an excessively large air pressure. Therefore, it is possible to reduce the burden on the subject.

[Brief description of drawings]

FIG. 1 is an overall view showing a schematic configuration of a first embodiment of the present invention.

FIG. 2 is a block diagram of a measurement circuit which is an intraocular pressure value conversion means of the embodiment shown in FIG.

3 is a graph of a correlation function established by the measurement circuit shown in FIG.

FIG. 4 is a cross-sectional view showing a detailed configuration of the fluid discharge means shown in FIG.

FIG. 5 is a graph of a correlation function obtained by modifying the measurement circuit shown in FIG.

FIG. 6 is a main part configuration diagram showing a second embodiment of the present invention.

FIG. 7 is a configuration diagram of a main part showing a third embodiment of the present invention.

8 is an explanatory diagram for explaining the embodiment shown in FIG. 7, and is a diagram showing a cross-sectional image of a cornea subjected to a predetermined deformation in a curved state by a broken line.

9 is an explanatory diagram for explaining the embodiment shown in FIG. 7, and is a diagram showing by a chain double-dashed line a corneal cross-sectional image that has undergone predetermined deformation in the applanation state.

FIG. 10 is a main part configuration diagram showing a fourth embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Fluid discharge means 2 ... Corneal 3 ... Injection optical system (corneal deformation | transformation detection means) 6 ... Cylinder 10 ... Nozzle cylinder part 12 ... Piston 24 ... Measurement circuit (valve drive control part) 47 ... Electromagnetic valve drive circuit (valve drive control) Part) 46 ... Solenoid valve (valve)

Claims (1)

[Claims] 1. An air discharging means for discharging air whose pressure changes with time from a nozzle portion to a cornea of an eye by a piston capable of moving forward and backward in a cylinder, and a cornea for detecting a deformation of the cornea of the eye. In a non-contact tonometer having a deformation detecting means, a valve for releasing the air in the cylinder and a predetermined deformation of the cornea of the eye to be detected are detected based on the signal from the corneal deformation detecting means. A non-contact tonometer, which is provided with a valve drive control unit for opening the valve based on the above.