JP2002224044A - Noncontact type tonometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a noncontact type tonometer capable of efficiently obtaining a measuring result corresponding to a plurality of phase positions of a pulsation fluctuation. SOLUTION: This noncontact type tonometer has a fluid injection means for injecting fluid into an optometrical eye by receiving an injection signal, and measures intraocular pressure on the basis of detecting a deformation state of an optometrical cornea by injection of the fluid. The tonometer has a detecting means for detecting pulsation of a subject, an instruction signal input means for inputting an intracoular pressure measurement execution instruction signal, a measuring timing determining means for determining the measuring timing for outputting the injection signal on the basis of the detected pulsation so that an intraocular pressure measuring result in synchronism with different phase positions in the pulsation can be respectively obtained by a prescribed frequency, and a control means for controlling output of the injection signal on the basis of the determined timing and input of the instruction signal.

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 for measuring intraocular pressure by compressing a fluid, spraying the compressed fluid onto an eye to be examined, and detecting a deformed state of a cornea of the eye to be examined.

[0002]

2. Description of the Related Art Intraocular pressure has a temporal variation synchronized with blood pulsation (pulse wave). It is unclear which point in the temporal change is measured when a non-contact tonometer measures the time randomly. If the number of measurements is small, in spite of the fact that the intraocular pressure is actually high, it will measure the lowest point in the intraocular pressure fluctuation, and in the case of screening such as mass screening,
Increased intraocular pressure may be overlooked.

For this reason, while sampling the pulsation,
A non-contact tonometer that measures intraocular pressure at the timing of an output signal synchronized with a predetermined pulsation phase position has been proposed.

[0004]

By the way, in the change time of the intraocular pressure synchronized with the pulsation, which information is desired depends on the purpose. However, in the conventional apparatus, measurement must be performed by selecting one phase position, which is troublesome in obtaining measurement results at a plurality of phase positions. Also,
When evaluating a measured value with a contact-type applanation tonometer, not only a measurement result at an arbitrary phase position but also an average intraocular pressure value is required.

The present invention has been made in view of the above-mentioned problems of the prior art,
An object of the present invention is to provide a non-contact tonometer capable of efficiently obtaining measurement results corresponding to a plurality of phase positions of pulsation fluctuation.

[0006]

Means for Solving the Problems In order to solve the above problems, the present invention is characterized by having the following configuration.

(1) A non-contact type which includes a fluid ejecting means for ejecting a fluid to an eye to be inspected in response to an ejection signal, and measures an intraocular pressure based on detecting a deformed state of the cornea of the eye due to the ejection of the fluid. In the tonometer, a detecting means for detecting a pulsation of the subject, an instruction signal inputting means for inputting an intraocular pressure measurement execution instruction signal, and an intraocular pressure measurement result synchronized with a different phase position in the pulsation can be obtained a predetermined number of times. As described above, the measurement timing determining means for determining the measurement timing for outputting the injection signal based on the detected pulsation, and the control means for controlling the output of the injection signal based on the determined timing and the input of the instruction signal. And the following.

(2) In the non-contact tonometer according to (1), the different phase positions in the pulsation include at least a peak and a bottom in the phase of the pulsation, and the tonometer obtains an average tonometry value from the measurement results of the peak and the bottom. Is provided.

(3) In the non-contact tonometer of (2), the tonometry value at the peak, the tonometry value at the bottom, and the average tonometry value in the pulsation phase are output in such a form that they can be identified. It is characterized by comprising output means.

(4) In the non-contact tonometer of (1), a measurement mode in which a measurement result is obtained at at least one of a peak position, a bottom position, or an arbitrarily designated phase position in the detected pulsation; It is characterized by comprising a mode selecting means for selecting a mode in which measurement results are automatically obtained a predetermined number of times at the peak position and the bottom position, respectively.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a schematic side view of a fluid ejection mechanism of a non-contact tonometer and a main part of a control system.

Reference numeral 1 denotes a cylinder for air compression, which is provided to be inclined with respect to the horizontal line of the main body of the tonometer. Reference numeral 2 denotes a piston. Reference numeral 3 denotes a rotary solenoid. When a charge (current or voltage) as driving energy is applied to the rotary solenoid 3, the piston 2 is moved upward along the cylinder 1 via the arm 4 and the connecting rod 5. Push up.
The air compressed in the air compression chamber 11 that communicates with the cylinder unit 1 due to the rise of the piston 2 is ejected from the nozzle 6 toward the cornea of the eye E to be examined. Also, the rotary solenoid 3
Is provided with a coil spring (not shown). When the applied charge is cut, the piston 2 which has been raised by the urging force of the coil spring in the downward direction is lowered and returned to the initial position.

Reference numeral 7 denotes a transparent glass plate which holds the nozzle 6 and transmits observation light, alignment light and the like. The glass plate 7 serves as a side wall of the air compression chamber 11. Reference numeral 9 denotes a transparent glass plate provided on the back surface of the nozzle 6, which constitutes a rear wall of the air compression chamber 11, and transmits observation light and alignment light. Behind the glass plate 9, an optical system 8 for observation and alignment described later is arranged. Reference numeral 12 denotes a pressure sensor that detects the pressure of the air compression chamber 11.

Reference numeral 20 denotes a control unit, which is a pressure detection processing circuit 21 for the pressure sensor 12, a signal detection processing circuit 22 for a photodetector 56 of a corneal deformation detection optical system described later, and a one-dimensional position detection element for detecting a working distance. 57 signal detection processing circuit 26,
A signal detection processing circuit 27 for the CCD camera 35, a pulsation detection processing circuit 28 for the pulsation detector 18, a drive circuit 23 for driving the rotary solenoid 3, and a memory 24 for storing measurement data, measurement control conditions, and the like. Is connected. An input unit 25 includes a measurement mode selection switch 25a and the like. 25b is a measurement start switch.

As shown in FIG. 2, the pulsation detector 18 is attached to a forehead pad 17 provided in a face support unit 16 for supporting the face of the subject to detect the pulsation of the subject. . In the present embodiment, the pulsation detector 18 is provided on the forehead pad 17 in order to obtain a phase substantially the same as the phase of the pulsation fluctuation in the eyeball. However, the pulsation detector 18 is provided at a position that comes into contact with the subject's face, such as a chin rest. It may be provided. The pulsation detector 18 also has a function of determining whether the subject's forehead is stably in contact with the forehead rest 17.

The pulsation detector 18 includes a light emitting unit and a light receiving unit. The light emitting unit is a light emitting diode (LED) having a near infrared wavelength corresponding to the absorption spectrum of blood hemoglobin and a narrow emission wavelength band. It is a photodiode.
Blood hemoglobin has a strong absorption spectrum for light in a certain wavelength band. The reflected light of the living body when irradiated with light in this wavelength band changes in accordance with the amount of hemoglobin that changes with the change in the volume of the blood vessel. Therefore, the pulsation is detected by changing the intensity of the reflected light into an electric signal. Since blood hemoglobin has a broad absorption spectrum not only in the near infrared region but also in the visible region, a white LED may be used as the light emitting portion. In this case, it is preferable that the light receiving section has sensitivity in a wide wavelength range, such as a photoconductive element.

In FIG. 2, reference numeral 15 denotes a measuring unit in which a fluid ejecting mechanism and an optical system to be described later are arranged. The measuring unit 15 is mounted on a movable base 14 which horizontally moves on a fixed base 13. The movable table 14 is moved by operating the joystick 19, and the measuring unit 15 is moved up and down by operating the rotation knob of the joystick 19.

FIG. 3 is a diagram showing a main part of the optical system for the upper view of the non-contact tonometer. The image of the eye to be inspected illuminated by the infrared illumination light source 30 is transmitted to the CCD camera 3 via a beam splitter 31, an objective lens 32, a beam splitter 33, and a filter.
5 is imaged. The filter 34 transmits light from the light source 30 and the light source 40 for alignment, and has a characteristic of being impermeable to light from an LED 50 for detecting corneal deformation, which will be described later. CCD
The image formed on the camera 35 is displayed on a monitor 36.

Reference numeral 40 denotes an infrared LED for alignment. The infrared light projected through the projection lens 41 is reflected by the beam splitter 31 and projected on the eye to be examined from the front. The corneal bright spot formed at the apex of the cornea by the LED 40 is transmitted through the beam splitter 31 to the filter 34 to C.
It forms an image on the CD camera 35 and is used for alignment detection in the vertical and horizontal directions.

Reference numeral 45 denotes an LED for projecting a fixation target, and LE
The light of the fixation target 46 illuminated by D45
7, the light is reflected by the beam splitter 33 and travels toward the eye E. The examiner performs the measurement while the fixation target 46 is fixed to the subject's eye.

Reference numeral 50 denotes an infrared LED for detecting corneal deformation, and the light emitted from the LED 50 is converted into a substantially parallel light beam by a collimator lens 51 and projected onto the cornea of the eye to be examined. The light reflected by the cornea is received by the light receiving lens 52, the light source 30 and the light source 4.
After passing through a filter 53 having the property of being opaque to zero light, the light is reflected by a beam splitter 54, passes through a pinhole plate 55, and is received by a photodetector 56. In the optical system for detecting corneal deformation, the eye to be examined is in a predetermined deformed state (flat state).
In this case, the light detector 56 is arranged such that the amount of light received by the light detector 56 is maximized.

The corneal deformation detecting optical system also functions as a part of the working distance detecting optical system, and the light projected from the LED 50 and reflected by the cornea forms an index image which is a virtual image of the LED 50. The light of the index image passes through a light receiving lens 52, a filter 53, and a beam splitter 54, and is incident on a one-dimensional position detecting element 57 such as a PSD or a line sensor. When the subject's eye (cornea) moves in the working distance direction, the LED 50
The control unit 20 also obtains working distance information based on the output signal from the one-dimensional position detecting element 57 because the index image of the one-dimensional position detecting element 57 also moves on the one-dimensional position detecting element 57.

The operation of the non-contact tonometer having the above configuration will be described.

First, the examiner selects a measurement mode for determining a phase position at which the intraocular pressure is measured in the pulsation cycle with the switch 25a. As shown in FIG. 4, the measurement mode includes a mode in which measurement is performed at the peak P of the pulsation phase, a mode in which measurement is performed at the bottom B of the pulsation phase, a mode in which the measurement is performed at an arbitrary point N in the pulsation phase, and a peak P in which the pulsation phase is measured. A mode for measuring the bottom B a predetermined number of times (for example, two times) is provided. The position of the arbitrary point N can be set by a switch of the input unit 25 such as% of the height of the amplitude or% of one cycle. In the mode in which the peak P and the bottom B are measured a predetermined number of times, an average intraocular pressure is automatically calculated. The average value of the intraocular pressure is effective when evaluating a measurement value obtained by a contact applanation type Goldman tonometer.

Next, the subject is instructed to make contact with the forehead 17 and the pulsation detector 18 attached to the forehead 17 measures the pulsation of the subject. The pulsation detector 18
The pulsation detection processing circuit 2 converts the subject's pulsation into an electric signal.
Send to 8. The pulsation waveform signal detected by the pulsation detection processing circuit 28 is input to the control unit 20, and the control unit 20 samples the pulsation waveform signal at a predetermined sampling time Ts as shown in FIG. Sampling time Ts
Is set to be performed until a predetermined time (5 seconds or the like) or a predetermined cycle (one cycle is sufficient, but preferably three cycles or more) is obtained. During this sampling time, the subject is urged to stand still so that a pulsating waveform signal can be stably obtained. If a stable pulsation waveform signal can be sampled, the controller 20 calculates the phase and period of the subsequent pulsation from the sampling data (the phase and period of the pulsation are preferably obtained from the average of the pulsation waveforms that can be sampled stably). , To calculate the period of the periodic intraocular pressure measurement.

When the signal from the pulsation detector 18 is not obtained, it can be understood that the subject's forehead does not sufficiently contact the forehead rest 17 and the face is not fixed stably. In this case, a message to the effect that the face is not fixed may be displayed on the monitor 36 to inform the examiner.

FIG. 5 shows an example of a mode in which the intraocular pressure is measured at the peak P of the pulsation. S1 indicates the timing of the peak P of the pulsation phase expected after the sampling time Ts.
S2 indicates an intraocular pressure measurement timing at which a signal S3 for driving the solenoid 3 is output. This timing S2 is
After outputting the solenoid drive signal S3, the cornea is flattened by the injection of compressed air from the nozzle 6 (photodetector 56
From the timing S1 until the peak of the applanation signal Q output from the timing S1). The intraocular pressure measurement timing S2 is repeated for each pulsation cycle Ta.

The applanation detection time Tapl will be described.
The time during which the peak of the applanation signal Q is obtained after the output of the solenoid drive signal S3 differs depending on the rise of the intraocular pressure of the eye to be examined and the rise of the ejection pressure. The rise of the discharge pressure after outputting the solenoid drive signal S3 can be obtained in advance. Therefore, if the intraocular pressure value of the eye to be examined can be predicted, the applanation detection time Tapl can also be predicted. When the second and subsequent measurements are performed with the same subject's eye, the previously measured measured intraocular pressure value is used as the predicted value, and the applanation detection time Tapl measured by the control unit 20 at that time is used in the next measurement. Good. In the second and subsequent measurements, the intraocular pressure measurement timing S2 is obtained by using the applanation detection time Tapl in the immediately preceding measurement.
The peak of the pulsation waveform and the peak of the applanation signal Q easily match. In the first measurement, in addition to setting the applanation detection time Tapl using an average intraocular pressure value, if the intraocular pressure of the eye to be examined can be predicted to some extent, the intraocular pressure value is input to the input unit 2.
5 to set the applanation detection time Tapl.

When the intraocular pressure measurement timing S2 is obtained from the pulsation sampling data, the control unit 20 displays the fact on the monitor 36 to enable the intraocular pressure measurement. The examiner operates the joystick 19 and the like based on the alignment information displayed on the monitor 36 to move the measuring unit 15 and adjust the alignment. The vertical and horizontal alignment adjustment is performed so that the corneal bright spot formed by the LED 40 has a predetermined relationship with a reticle (not shown) displayed on the monitor 36. The alignment adjustment in the working distance direction is performed according to the distance index displayed based on the working distance information obtained from the one-dimensional position detecting element 57. For details of the alignment adjustment, refer to Japanese Patent Application Laid-Open No. 7-23907 filed by the present applicant. Further, the measuring unit 1 based on the detection information of the alignment index image.
5 can be moved for automatic alignment.

The controller 20 obtains an alignment completion signal R when the index image detected by the one-dimensional position detecting element 57 and the index image detected by the CCD camera 35 fall within predetermined allowable ranges. When the alignment completion signal R is obtained, the signal is used as a measurement execution instruction signal, and a solenoid drive signal S3 is output in synchronization with the intraocular pressure measurement timing S2 immediately after that, to execute the measurement. That is, the control unit 20 applies an electric charge as operable drive energy to the rotary solenoid 3 via the drive circuit 23 and drives the rotary solenoid 3. When the measurement is performed manually without using the alignment completion signal R, the solenoid drive signal S3 is synchronized with the intraocular pressure measurement timing S2 immediately after the trigger signal is input from the measurement start switch 25b.
Is output.

The driving of the rotary solenoid 3 raises the piston 2, the air in the air compression chamber 11 is compressed by the piston 2, and the compressed air is blown from the nozzle 6 toward the cornea of the eye E to be examined. The cornea of the eye E is gradually deformed by the compressed air blown, and when the cornea reaches a flat state, the maximum amount of light is incident on the photodetector 56. The output signal from the photodetector 56 and the output signal from the pressure sensor 12 are sequentially processed and input to the control unit 20. The control unit 20 obtains an average pressure of the pressure Pr obtained in a predetermined time width before and after the time when the applanation signal Q output from the photodetector 56 shows a peak, and obtains an intraocular pressure Find the value.

In the case of the second and subsequent consecutive measurements, the solenoid drive signal S3 can be output after waiting for the charge time for driving the solenoid 3 and the air suction time into the cylinder unit 1. It is said.

As described above, the step of detecting pulsation and the step of measuring intraocular pressure are separated from each other, and the pulsation detected in a state where the subject is stationary beforehand corresponds to the periodic pulsation corresponding to the pulsation of the subject occurring after that. Since the measurement timing is set, even if the subject blinks on the way or the body motion occurs repetitively due to repeated measurement and the pulsation cannot be detected, the intraocular pressure measurement at the expected pulsation cycle position Can be performed smoothly. That is, in FIG. 5, since the measurement timing corresponding to a certain pulsation of the subject indicated by the dotted line is determined based on the sampling of the pulsation that occurred earlier than the pulsation that occurred immediately before, the subject indicated by the dotted line was measured. Even if the pulsation of the examiner cannot be detected, the measurement timing corresponding to the pulsation is determined.

Normally, the measurement timing S2 is determined as described above. However, it is preferable that sampling of the pulse rate is continuously performed, and the measurement timing S2 is updated to a new one at any time. When the pulsation is no longer detected on the way, the measurement timing S2 is determined from the pulsation detected before that. For example, as shown in FIG. 6, the sampling time of 5 seconds is repeated, and the measurement timing S2 of the intraocular pressure measurement time is determined for each sampling. When the pulsation cannot be obtained stably in the middle, the measurement timing S2 determined previously remains unchanged.

As shown in FIG. 7, the measurement timing S2 may be updated when a good waveform is obtained during continuous sampling. Also in this case, when the pulsation cannot be detected on the way, the measurement timing S2 determined previously can be used, so that the measurement can be performed smoothly. When a good waveform is obtained, the timing S2 is switched to a new timing at any time, so that the pulsation synchronization deviation with the lapse of time is reduced, and the accuracy is improved.

As described above, if the sampling time Ts is one cycle of pulsation, every time one pulsation waveform can be detected, the measurement timing S2 is determined at any time by the cycle and phase, and the pulsation becomes longer. If it cannot be detected, 1
The immediately preceding measurement timing S2 is periodically repeated. That is, two or more periodic measurement timings S2 corresponding to the pulsation of the subject that occur after the pulsation detected while the subject is stationary are determined in advance.

Next, a case where a mode in which the peak P and the bottom B of the pulsation phase are measured a predetermined number of times will be described. In this mode, the intraocular pressure is automatically measured twice for the same eye at the peak and the bottom of the pulsation phase.

As shown in FIG. 8, the control unit 20 obtains the phase and period of the pulsation from the sampling data, and measures the intraocular pressure measurement timing S2p corresponding to the phase peak P of the pulsation and the intraocular pressure measurement corresponding to the phase bottom B of the pulsation. The timing S2b is obtained by calculation so as to be shifted forward by the applanation detection time Tapl in the same manner as described above. Intraocular pressure measurement timing S2p, S2
b is continuously determined in accordance with the pulsation cycle.

After the sampling of the pulsation, when the alignment completion signal R is inputted by the alignment adjustment, the controller 20 outputs the solenoid drive signal S3 in synchronization with the later of the intraocular pressure measurement timings S2p and S2b. In FIG. 8, after the completion of the alignment completion signal R, first, the intraocular pressure measurement timing S2b of the bottom B comes, and then the peak P
Comes at the intraocular pressure measurement timing S2p. In this case, since the bottom intraocular pressure measurement timing S2b comes first, the first measurement result corresponds to the bottom B. The reason that the measurement of the intraocular pressure at the peak P cannot be performed immediately after the bottom is because the charge time for driving the solenoid and the time for sucking air into the cylinder unit 1 are required. After the compressed air can be injected, the alignment completion signal R is input again. Since the intraocular pressure measurement timing S2p comes earlier this time, the solenoid drive signal S3 is output in synchronization with this timing. The measurement result at this time corresponds to the peak P.

Thus, the intraocular pressure measurement timings S2p, S2p
The control unit 20 controls the measurement order such that the measurement synchronized with the earlier of 2b is performed, and the measurement results are obtained twice each. If the measurement result at the peak P is obtained twice first due to the input timing of the alignment completion signal R, the order is controlled so that the bottom B is next twice. When the peak P and the bottom B are measured twice each, the average value of the intraocular pressure is automatically calculated.

The measurement result is displayed on the monitor 36 each time the measurement is performed, and when the measurement results are obtained twice, a message indicating the end of the measurement is displayed on the monitor 36. FIG. 9 shows an example of the screen at this time, and reference numeral 80 denotes a message indicating the end of measurement. At the bottom of the screen, each measurement result is displayed separately. In the example of FIG. 9, the measurement result corresponding to the peak of the pulsation cycle phase is displayed next to the display “P” on the screen, and the measurement result corresponding to the bottom of the pulsation cycle phase is displayed on the screen “B”. Is displayed next to. Further, next to the display “Av” on the screen, an average value obtained by calculation is displayed. In the case of printing and outputting with a printer (not shown), each measurement result is similarly divided and output so as to be able to identify which one. The same applies to the case of outputting data to an external computer. In this case, the displayed “P” and “B” indicate which of the predetermined timings has been executed.

[0042]

As described above, according to the present invention,
Measurement results corresponding to different phase positions of pulsation fluctuation can be efficiently obtained. Further, an average intraocular pressure value in pulsation fluctuation can be easily obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic side configuration of an air compression mechanism and a control system.

FIG. 2 is a diagram showing an appearance of the apparatus and a mounting location of a pulsation detector.

FIG. 3 is a view of the optical system near the nozzle of the air compression mechanism as viewed from above. .

FIG. 4 is a diagram illustrating peaks, bottoms, and arbitrary points of pulsation.

FIG. 5 is a diagram illustrating timings of pulsation and intraocular pressure measurement.

FIG. 6 is a diagram illustrating a timing chart for determining a new intraocular pressure measurement timing signal as needed with respect to a sampling time.

FIG. 7 is a diagram illustrating a timing chart for determining a new intraocular pressure measurement timing signal as needed for a sampling time at which a good waveform is obtained.

FIG. 8 is a diagram illustrating a timing chart for repeatedly measuring intraocular pressure at the peak and bottom of pulsation.

FIG. 9 is a diagram illustrating an example of a display screen of a measurement result.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder part 2 Piston 3 Rotary solenoid 12 Pressure sensor 18 Pulsation detector 20 Control part 25 Input part 25a Selection switch 25b Measurement start switch 28 Pulsation detection processing circuit 36 Monitor 50 LED 56 Photodetector

Claims (4)

[Claims] 1. A non-contact eye comprising a fluid ejecting means for ejecting a fluid to an eye to be inspected upon receiving an ejection signal, and measuring an intraocular pressure based on detecting a deformed state of a cornea of the eye due to the ejection of the fluid. In the tonometer, a detecting means for detecting a pulsation of the subject, an instruction signal inputting means for inputting an intraocular pressure measurement execution instruction signal, and an intraocular pressure measurement result synchronized with a different phase position in the pulsation can be obtained a predetermined number of times. Measuring timing determination means for determining a measurement timing for outputting the injection signal based on the detected pulsation; and control means for controlling the output of the injection signal based on the determined timing and the input of the instruction signal. And a non-contact tonometer. 2. The non-contact tonometer according to claim 1, wherein the different phase positions in the pulsation include at least a peak and a bottom in the phase of the pulsation, and further, the tonometer calculates an average intraocular pressure value from a measurement result of the peak and the bottom. A non-contact tonometer characterized by comprising a calculation means for determining. 3. The non-contact tonometer according to claim 2, wherein the output is output in such a manner that the peak intraocular pressure value, the bottom intraocular pressure value, and the average intraocular pressure value in the pulsation phase can be identified. Non-contact tonometer characterized by comprising means. 4. The non-contact tonometer according to claim 1, wherein a measurement mode in which a measurement result is obtained at at least one of a peak position, a bottom position, or an arbitrarily designated phase position in the detected pulsation; A non-contact tonometer, comprising: a mode selection unit that selects a mode in which measurement results are automatically obtained a predetermined number of times at a position and a bottom position.