JP3730521B2 - Non-contact tonometer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a non-contact tonometer that measures intraocular pressure by compressing a fluid and spraying the fluid onto a subject's eye and detecting the deformation state of the subject's eye cornea.
[0002]
[Prior art]
The intraocular pressure has temporal fluctuations synchronized with blood pulsation (pulse wave). When the time is measured randomly with a non-contact tonometer, it is unclear which point in the temporal change is being measured. When the number of measurements is small, the intraocular pressure fluctuation is actually measured, but the lowest point in the fluctuation of intraocular pressure is measured, and increased intraocular pressure may be overlooked during screening such as mass screening. is there.
[0003]
For this reason, a non-contact tonometer that measures intraocular pressure at the timing of an output signal synchronized with a predetermined phase position of the pulsation while sampling the pulsation has been proposed.
[0004]
[Problems to be solved by the invention]
By the way, which point of information is desired in the intraocular pressure change time synchronized with the pulsation varies depending on the purpose. However, in the conventional apparatus, it is necessary to select one phase position and perform measurement, which is troublesome in obtaining measurement results of a plurality of phase positions. In addition, when evaluating a measurement 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.
[0005]
In view of the above-described problems of the prior art, an object of the present invention is to provide a non-contact tonometer that can efficiently obtain measurement results corresponding to a plurality of phase positions of pulsation fluctuations.
[0006]
[Means for Solving the Problems]
In order to solve the above problems, the present invention is characterized by having the following configuration.
[0007]
(1) In a non-contact tonometer that includes fluid ejecting means that ejects fluid to an eye to be examined in response to an ejection signal, and that measures intraocular pressure based on detecting a deformed state of the subject's eye cornea due to ejection of the fluid The detection means for detecting the pulsation of the subject, the instruction signal input means for inputting the intraocular pressure measurement execution instruction signal, and the intraocular pressure measurement results synchronized with different phase positions in the pulsation, respectively, for a predetermined number of times. Measurement timing determining means for obtaining a measurement timing for outputting the injection signal based on the detected pulsation, control means for controlling the output of the injection signal based on the obtained timing and the input of the instruction signal, and detection Measurement mode in which measurement results can be obtained at at least one of the peak position, bottom position, or arbitrarily specified phase position of the pulsation, and the peak and bottom positions And a mode selection means for selecting a measurement mode so that each measurement result is automatically obtained a predetermined number of times .
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a present Example is described based on drawing. FIG. 1 is a diagram showing a side view of a fluid ejection mechanism of a non-contact tonometer and a main part of a control system.
[0012]
Reference numeral 1 denotes a cylinder for air compression, which is provided inclined with respect to the horizontal line of the tonometer main body. 2 is a piston, 3 is a rotary solenoid, and when charge (current, voltage) as drive 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 portion 1 as the piston 2 rises is ejected from the nozzle 6 toward the cornea of the eye E. The rotary solenoid 3 is provided with a coil spring (not shown). When the applied charge is cut, the piston 2 that has been lifted by the biasing force in the downward direction of the coil spring is lowered and returned to the initial position.
[0013]
A transparent glass plate 7 holds the nozzle 6 and transmits observation light, alignment light, and the like. The glass plate 7 is a side wall of the air compression chamber 11. A transparent glass plate 9 is provided on the back surface of the nozzle 6 and constitutes the rear wall of the air compression chamber 11 and transmits observation light and alignment light. Behind the glass plate 9 is an optical system 8 for observation and alignment described later. A pressure sensor 12 detects the pressure in the air compression chamber 11.
[0014]
Reference numeral 20 denotes a control unit for the pressure detection processing circuit 21 for the pressure sensor 12, the signal detection processing circuit 22 for the photodetector 56 of the corneal deformation detection optical system, which will be described later, and the one-dimensional position detection element 57 for the working distance detection. A 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, measurement data, measurement control conditions, etc. A memory 24 for storing is connected. An input unit 25 includes a measurement mode selection switch 25a and the like. Reference numeral 25b denotes a measurement start switch.
[0015]
In order to detect the subject's pulsation, the pulsation detector 18 is attached to a forehead pad 17 provided in a face support unit 16 for supporting the subject's face as shown in FIG. 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 pulsation fluctuation in the eyeball. However, the pulsation detector 18 is located at a position in contact with the face of the subject such as a chin rest. It may be provided. The pulsation detector 18 also has a function of determining whether or not the subject's forehead is in stable contact with the forehead pad 17.
[0016]
The pulsation detector 18 includes a light emitting part and a light receiving part. The light emitting part is a light emitting diode (LED) having a narrow emission wavelength band at a near infrared wavelength corresponding to the absorption spectrum of blood hemoglobin, and the light receiving part is a photodiode. is there. Blood hemoglobin has a strong absorption spectrum for light in a certain wavelength band. Since the reflected light of the living body when irradiated with light in this wavelength band changes according to the amount of hemoglobin that changes with the change in the volume of the blood vessel, the intensity of this reflected light is changed to an electrical signal to detect pulsation. Since blood hemoglobin has a wide 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 unit. In this case, it is preferable that the light receiving part has sensitivity in a wide wavelength region such as a photoconductive element.
[0017]
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 moving table 14 that horizontally moves on the fixed base 13. The movable table 14 is moved by operating the joystick 19, and the measurement unit 15 is moved up and down by operating the rotary knob of the joystick 19.
[0018]
FIG. 3 is a principal view of the upper-view optical system of the non-contact tonometer. The eye image illuminated by the infrared illumination light source 30 forms an image on the CCD camera 35 via the beam splitter 31, the objective lens 32, the beam splitter 33 and the filter 34. The filter 34 transmits light from the light source 30 and the light source 40 for alignment, and has an opaque characteristic to light from the LED 50 for detecting corneal deformation described later. The image formed on the CCD camera 35 is displayed on the monitor 36.
[0019]
Reference numeral 40 denotes an alignment infrared LED. The infrared light projected via the projection lens 41 is reflected by the beam splitter 31 and projected onto the eye to be examined from the front. The corneal bright spot formed at the apex of the cornea by the LED 40 forms an image on the CCD camera 35 via the beam splitter 31 to the filter 34 and is used for alignment detection in the vertical and horizontal directions.
[0020]
Reference numeral 45 denotes a fixation target projection LED. The light of the fixation target 46 illuminated by the LED 45 passes through the projection lens 47 and is then reflected by the beam splitter 33 toward the eye E. The examiner performs the measurement while fixing the fixation target 46 to the eye to be examined.
[0021]
Reference numeral 50 denotes an infrared LED for detecting corneal deformation. The light emitted from the LED 50 is made into a substantially parallel light beam by the collimator lens 51 and projected onto the cornea of the eye to be examined. The light reflected by the cornea passes through a filter 53 having a non-transmission characteristic with respect to the light of the light receiving lens 52, the light source 30, and the light source 40, and then is reflected by a beam splitter 54 and passes through a pinhole plate 55 to detect light. The light is received by the device 56. The corneal deformation detection optical system is arranged so that the amount of light received by the photodetector 56 is maximized when the eye to be examined is in a predetermined deformed state (flat state).
[0022]
The corneal deformation detection optical system also serves as a part of the working distance detection optical system, and the light projected from the LED 50 and reflected by the cornea forms an index image that is a virtual image of the LED 50. The light of the index image passes through the light receiving lens 52, the filter 53, and the beam splitter 54 and enters the one-dimensional position detection element 57 such as a PSD or a line sensor. When the eye to be examined (cornea) moves in the working distance direction, the index image by the LED 50 also moves on the one-dimensional position detection element 57, so the control unit 20 operates the working distance information based on the output signal from the one-dimensional position detection element 57. Get.
[0023]
The operation of the non-contact tonometer having the above configuration will be described.
[0024]
First, the examiner uses the switch 25a to select a measurement mode as to which phase position in which the pulsation period is to be measured. In this measurement mode, as shown in FIG. 4, (1) a mode for measuring at the peak P of the pulsation phase, (2) a mode for measuring at the bottom B of the pulsation phase, and (3) measurement at an arbitrary point N of the pulsation phase. (4) A mode for measuring the peak P and bottom B of the pulsation phase a predetermined number of times (for example, twice) is prepared. The position of the arbitrary point N can be set by a switch of the input unit 25 such as what percentage of the amplitude height or what percentage of one period. In the mode in which the peak P and the bottom B are measured a predetermined number of times, the intraocular pressure average value is automatically calculated. The intraocular pressure average value is effective when evaluating the measurement value with a contact applanation type Goldman tonometer.
[0025]
Next, the subject is instructed so that the forehead of the subject contacts the forehead pad 17, and the pulsation of the subject is measured by the pulsation detector 18 attached to the forehead pad 17. The pulsation detector 18 converts the subject's pulsation into an electrical signal and sends it to the pulsation detection processing circuit 28. 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. The sampling time Ts is set to be performed until a predetermined time (for example, 5 seconds) or a predetermined period (one period is sufficient, but preferably three or more periods) is obtained. During this sampling time, the subject is prompted to stop so that the pulsation waveform signal can be stably obtained. If the control unit 20 can sample a stable pulsation waveform signal, after obtaining 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). Calculating periodic intraocular pressure measurement time.
[0026]
In addition, when the signal from the pulsation detector 18 is not obtained, it turns out that the subject's forehead is not sufficiently in contact with the forehead pad 17 and the fixation of the face is not stable. In this case, a message indicating that the face is not fixed on the monitor 36 may be displayed on the monitor 36 to notify the examiner.
[0027]
The example of FIG. 5 is an example in the mode of measuring intraocular pressure at the peak P of pulsation. S1 indicates the timing of the peak P of the pulsation phase expected after the sampling time Ts. S2 indicates the intraocular pressure measurement timing at which the signal S3 for driving the solenoid 3 is output. At this timing S2, after the solenoid drive signal S3 is output, the applanation is detected until the cornea is flattened by the injection of compressed air from the nozzle 6 (until the peak of the applanation signal Q output from the photodetector 56). It is obtained at the timing determined from the timing S1 by the time Tapl. The intraocular pressure measurement timing S2 is repeated every pulsation cycle Ta.
[0028]
The applanation detection time Tapl will be described. The time for which the peak of the applanation signal Q is obtained after the solenoid drive signal S3 is output varies depending on the rise of the intraocular pressure and the discharge pressure of the eye to be examined. 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 performing the second and subsequent measurements on the same eye, the previously measured measurement pressure value is used as a predicted value, and the applanation detection time Tapl measured by the control unit 20 at that time is used in the next measurement. It ’s fine. In the second and subsequent measurements, the peak of the pulsation waveform and the peak of the applanation signal Q can be easily matched by obtaining the intraocular pressure measurement timing S2 using the applanation detection time Tapl in the previous measurement. . In the first measurement, the applanation detection time Tapl is set 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 from the input unit 25. Then, the applanation detection time Tapl may be set.
[0029]
When the intraocular pressure measurement timing S2 is obtained from the sampling data of the pulsation, the control unit 20 displays that fact on the monitor 36 and makes the intraocular pressure measurement possible. The examiner moves the measurement unit 15 by operating the joystick 19 or the like based on the alignment information displayed on the monitor 36 to perform alignment adjustment. In the vertical and horizontal alignment adjustments, the corneal bright spots formed by the LEDs 40 are in 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 detection element 57. For details of the alignment adjustment, refer to Japanese Patent Application Laid-Open No. 7-23907 by the present applicant. Further, the alignment can be automatically performed by moving the measurement unit 15 based on the detection information of the alignment index image.
[0030]
The control unit 20 obtains the alignment completion signal R when the index image detected by the one-dimensional position detection element 57 and the index image detected by the CCD camera 35 are within a predetermined allowable range. When the alignment completion signal R is obtained, this is used as a measurement execution instruction signal, and the solenoid drive signal S3 is output in synchronization with the intraocular pressure measurement timing S2 immediately after that to perform measurement. That is, the control unit 20 applies electric charges as operable driving energy to the rotary solenoid 3 through the driving circuit 23 to drive it. When the measurement is performed manually without using the alignment completion signal R, the solenoid drive signal S3 is output in synchronization with the intraocular pressure measurement timing S2 immediately after the trigger signal is input from the measurement start switch 25b.
[0031]
The piston 2 is raised by driving the rotary solenoid 3, the air in the air compression chamber 11 is compressed by the piston 2, and the compressed air is blown toward the cornea of the eye E from the nozzle 6. The cornea of the eye E is gradually deformed by the blown compressed air, and when the cornea reaches a flat state, the maximum amount of light enters 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 from this, the intraocular pressure is obtained. Find the value.
[0032]
In the case of continuous measurement after the second time, the solenoid drive signal S3 can be output after waiting for the charge time for driving the solenoid 3 and the intake time of air into the cylinder part 1. .
[0033]
As described above, the step of detecting pulsation and the step of measuring intraocular pressure are performed separately, and the periodic measurement timing corresponding to the pulsation of the subject subsequently generated from the pulsation detected in a state where the subject is stationary is previously obtained. Smooth measurement of intraocular pressure at the desired pulsation cycle position even when the subject blinks in the middle or body movements occur reflexively due to repeated measurements and pulsations cannot be detected. It can be carried out. That is, in FIG. 5, 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 before the pulsation that occurred immediately before. Even if the examiner's pulsation cannot be detected, the measurement timing corresponding to the pulsation is determined.
[0034]
Normally, the measurement timing S2 is determined as described above, but it is preferable to continuously sample the pulse rate and update the measurement timing S2 to a new one at any time. When the pulsation is not detected halfway, the measurement timing S2 is determined from the pulsation that could be 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 timing is determined for each sampling. When pulsation cannot be stably obtained on the way, the previously determined measurement timing S2 is maintained.
[0035]
Further, 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 previously determined measurement timing S2 can be used, so that the measurement can be performed smoothly. By switching the timing S2 to a new one at any time when a good waveform is obtained, the pulsation synchronization deviation with the passage of time is reduced, and the accuracy is improved.
[0036]
As described above, when the sampling time Ts is set to one period of pulsation, every time one pulsation waveform can be detected, the measurement timing S2 is determined at any time based on the period and phase, and pulsation cannot be detected. Will periodically repeat the previous measurement timing S2. That is, two or more periodic measurement timings S2 corresponding to the pulsation of the subject generated thereafter are determined from the pulsation detected in a state where the subject is stationary.
[0037]
Next, the case where the mode for measuring the peak P and the bottom B of the pulsation phase a predetermined number of times is selected will be described. In this mode, the intraocular pressure is automatically measured twice at the pulsation phase peak and bottom for the same eye.
[0038]
As shown in FIG. 8, the control unit 20 obtains the pulsation phase and period from the sampling data, and calculates the intraocular pressure measurement timing S2p corresponding to the pulsation phase peak P and the intraocular pressure measurement timing S2b corresponding to the pulsation phase bottom B. In the same manner as described above, the calculation is performed so as to shift the applanation detection time by Tapl. The intraocular pressure measurement timings S2p and S2b are continuously determined according to the pulsation period.
[0039]
When the alignment completion signal R is input by alignment adjustment after sampling the pulsation, the control unit 20 outputs the solenoid drive signal S3 in synchronization with the subsequent intraocular pressure measurement timing S2p or S2b, whichever is earlier. In FIG. 8, after receiving the alignment completion signal R, the bottom B intraocular pressure measurement timing S2b comes first, and then the peak P intraocular pressure measurement timing S2p comes. In this case, since the bottom intraocular pressure measurement timing S2b is first, the first measurement result corresponds to the bottom B. The reason why the intraocular pressure measurement of the peak P cannot be performed immediately after the bottom is that it takes time to charge the solenoid and charge the air into the cylinder portion 1. After the compressed air can be injected, the alignment completion signal R is input again. Since the intraocular pressure measurement timing S2p has come 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.
[0040]
Thus, the measurement synchronized with the earlier one of the intraocular pressure measurement timings S2p and S2b is executed, and the control unit 20 controls the measurement order so that the measurement results are obtained twice. If the measurement result at the peak P is obtained twice previously because of the input timing of the alignment completion signal R, the order is controlled such that the bottom B is performed twice next. If each of the peak P and the bottom B is measured twice, the intraocular pressure average value is automatically calculated.
[0041]
The measurement result is displayed on the monitor 36 every time the measurement is executed, and when the measurement result is obtained twice, a measurement end message is displayed on the monitor 36. FIG. 9 shows an example of the screen at this time, and 80 is a measurement end message. Each measurement result is distinguished and displayed at the bottom of the screen. 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”. It is displayed next to. Further, an average value obtained by calculation is displayed next to the display “Av” on the screen. In the case of printing output by a printer (not shown), the measurement results are similarly divided and output so that the measurement results can be identified. The same applies when outputting data to an external computer. In this case, the displayed “P” and “B” indicate at which timing of the timings determined in advance.
[0042]
【The invention's effect】
As described above, according to the present invention, measurement results corresponding to phase positions with different pulsation fluctuations can be obtained efficiently. Moreover, the average intraocular pressure value in the pulsation fluctuation can be easily obtained.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic side configuration and a control system of an air compression mechanism.
FIG. 2 is a diagram showing the appearance of the apparatus and the installation location of the pulsation detector.
FIG. 3 is a view of an optical system in the vicinity of a nozzle of an air compression mechanism as viewed from above. .
FIG. 4 is a diagram for explaining pulsation peaks, bottoms, and arbitrary points;
FIG. 5 is a diagram illustrating timing of pulsation and intraocular pressure measurement.
FIG. 6 is a diagram illustrating a timing chart for determining a new intraocular pressure measurement timing signal at any time with respect to a sampling time.
FIG. 7 is a diagram illustrating a timing chart for determining a new intraocular pressure measurement timing signal at any time with respect to a sampling time when 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 pulsations.
FIG. 9 is a diagram illustrating an example of a measurement result display screen.
[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 photodetectors

Claims (1)

In a non-contact tonometer that includes a fluid ejecting unit that ejects a fluid to an eye to be examined in response to an ejection signal, and that measures an intraocular pressure based on detecting a deformation state of the subject's cornea by ejecting the fluid. Detecting means for detecting a person's pulsation, instruction signal input means for inputting an intraocular pressure measurement execution instruction signal, and detecting the intraocular pressure measurement results synchronized with different phase positions in the pulsation for a predetermined number of times. Measurement timing determining means for obtaining a measurement timing for outputting the injection signal based on pulsation, control means for controlling the output of the injection signal based on the obtained timing and the input of the instruction signal, and in the detected pulsation Measurement mode that obtains measurement results at at least one of the phase peak position, bottom position, or arbitrarily specified phase position, and measurement at the peak position and bottom position. Non-contact type tonometer result is a mode selecting means for selecting a mode for measuring so as to obtain automatically a predetermined number of times, respectively, comprising: a.

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