JP2018161217A - Ophthalmologic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus effectively suppressing air jetting to a subject's eye in a tonometer for jetting a compressed air to the subject's eye to measure an intraocular pressure.SOLUTION: An ophthalmologic apparatus 100 includes: a chamber 120 for accumulating air to be jetted to a subject's eye; a pump 110 for applying pressure to the chamber 120; an opening/closing valve 141 disposed between the chamber 120 and the pump 110; and an optical system 123 applying measuring light to the subject's eye and detecting the reflected light from the subject's eye. The ophthalmologic apparatus causes the pump 110 to apply the pressure to the chamber 120, with the opening/closing valve 141 opened, and jets high-pressure air to the subject's eye, where the opening/closing valve 141 is closed on the basis of the light volume of the reflected light.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an ophthalmologic apparatus for measuring intraocular pressure.

  There is known a non-contact type ophthalmologic apparatus that measures intraocular pressure by blowing air onto an eyeball and optically measuring deformation of the eyeball at that time (see, for example, Patent Document 1).

  With this technique, since high-pressure air is jetted onto the eye to be examined, there is a concern about the burden on the eye to be examined. As a countermeasure to this problem, an electromagnetic valve for releasing the internal pressure to the outside is arranged in the air chamber that stores compressed air, and the electromagnetic valve is opened at an expected timing in anticipation of deformation of the eyeball. A technique for reducing the influence of high-pressure air blown on the eye to be examined by extracting air has been proposed (see, for example, Patent Document 2).

JP 2008-237516 A JP 2009-082514 A

  The form in which the pressure inside the apparatus of Patent Document 2 is released to the outside has a problem in that the operation sound, particularly the sound of the air coming out to the outside, causes discomfort to the subject. In addition, even when the pump is instructed to stop, the movable part such as the piston moves due to inertia, and the pumping action does not stop suddenly. For this reason, even after the operation of releasing the pressure, the internal pressure of the apparatus is increased simultaneously with the outflow of air from the electromagnetic valve, and there is a jet flow to the eye to be inspected due to the increase of the internal pressure. Due to this jet, the effect of reducing discomfort felt by the subject is not sufficient.

  In such a background, an object of the present invention is to provide a technique capable of effectively suppressing the injection of air to the subject's eye in a tonometer that measures the intraocular pressure by blowing compressed air onto the subject's eye.

  According to the first aspect of the present invention, there is provided a chamber chamber for storing air to be blown onto the eye to be examined, a pump for pressurizing the chamber chamber, an on-off valve disposed between the chamber chamber and the pump, and the eye to be examined. An optical system that irradiates measurement light and detects reflected light from the eye to be examined, and pressurizes the chamber chamber with the pump while the on-off valve is open, thereby blowing high-pressure air to the eye to be examined. The ophthalmic apparatus in which the on-off valve is closed based on the amount of the reflected light.

  The invention according to claim 2 is characterized in that, in the invention according to claim 1, the on-off valve is closed based on a time t at which the amount of the reflected light becomes maximum. According to a third aspect of the present invention, in the second aspect of the present invention, the on-off valve is closed after time t when the amount of the reflected light becomes maximum.

The invention according to claim 4 is the invention according to claim 2 or 3, wherein the time t is predicted based on a detection signal of the reflected light. According to a fifth aspect of the present invention, in the fourth aspect of the invention, assuming that the time when the time t can be predicted is t ₀ and the time when the on-off valve starts to be closed is t ₁ , t ₀ ≦ t ₁ <t.

  The invention according to claim 6 is the invention according to any one of claims 1 to 5, wherein the closing of the on-off valve is performed in a process in which an internal pressure of the chamber chamber is increasing. And A seventh aspect of the invention is characterized in that, in the invention according to any one of the first to sixth aspects, the pressure of the chamber chamber does not increase after the on-off valve is closed.

  ADVANTAGE OF THE INVENTION According to this invention, in the tonometer which blows compressed air on a to-be-tested eye and measures an intraocular pressure, the injection of the air to a to-be-tested eye can be suppressed effectively.

It is a conceptual diagram of the ophthalmologic apparatus of embodiment. It is a conceptual diagram which shows an example of an optical system. It is a block diagram which shows an example of a control system. It is a figure which shows an example of a pressure signal and an applanation signal. It is a flowchart which shows an example of a process. It is a flowchart which shows an example of a process.

1. First embodiment (overall configuration)
In FIG. 1, an ophthalmic apparatus 100 is shown. The ophthalmologic apparatus 100 measures the internal pressure of the eyeball (hereinafter referred to as intraocular pressure). Measurement of intraocular pressure is used for diagnosis of glaucoma, for example.

  The ophthalmic apparatus 100 includes a pump 110. The chamber 110 is pressurized by the pump 110, and high-pressure air is jetted from the nozzle 121 toward the eye to be examined. The pump 110 includes a pressurizing chamber 116. The pump 110 includes a cylindrical cylinder 111, and a piston 112 is housed in the cylinder 111 in a state in which the piston 112 can slide in the axial direction. The piston 112 is driven by a drive device 114 via a drive rod 113. The drive device 114 is a rotary solenoid that advances and retracts the drive rod 113 in the axial direction using a crank mechanism. The piston 112 is provided with an intake hole 115 penetrating in the axial direction. An irreversible valve 117 is fixed to the suction hole 115 on the pressure chamber 116 side by a fastening member 119.

  The irreversible valve 117 is made of a flexible resin film. When the piston 112 moves in the direction of the pressurizing chamber 116, the nonreciprocal valve 117 closes the intake hole 115, and the pressure in the pressurizing chamber 116 is changed to the intake chamber 118. It works so as not to come out. When the piston 112 moves away from the pressurizing chamber 116, the film-like irreversible valve 117 is deformed by the pressure difference between the intake chamber 118 and the air chamber 11, and the pressurization chamber 116 is turned from the intake chamber 118. Then, air moves through the intake hole 115.

  The pressurizing chamber 116 is connected to the chamber chamber 120 via the communication pipe 103. When the piston 112 moves in the upward direction in the drawing, the inside of the pressurizing chamber 116 is pressurized, and the chamber chamber 120 is pressurized via the communication pipe 103.

  The communication pipe 103 is provided with an open / close valve 141 that is opened and closed by a valve drive device 142. By the opening / closing valve 141, the pressurization chamber 116 and the chamber chamber 120 are opened or shut off. The on-off valve 141 is a butterfly valve. As the on-off valve 141, a ball valve, a gate valve, a globe valve, a check valve, or the like can be used. The valve driving device 142 includes a motor, a solenoid, an actuator, and the like that move a movable part of the opening / closing valve 141.

  An elongated cylindrical nozzle 121 is connected to the chamber chamber 120. The nozzle 121 is fixed to the housing of the ophthalmologic apparatus 100 via a light transmissive member 124 such as glass. In addition, an optical system 123 that outputs an applanation signal, which is a signal obtained by optically detecting a change in the shape of the eyeball, is connected to the chamber 120 via a plate-like optical filter 122. The chamber chamber 120 is provided with a pressure sensor 132 that measures the pressure inside the chamber chamber 120. A pressure signal which is a signal indicating the internal pressure of the chamber chamber 120 is output from the pressure sensor 132.

(Optical system)
FIG. 2 shows the configuration of the optical system 123 of FIG. The optical system 123 includes a light emitting unit 125 that emits measurement light. Light emission is performed by a light emitting element such as an LED. The light emission timing and the like are controlled by the light emission control unit 302 in FIG.

  As the emission wavelength, for example, near infrared light of 780 nm to 1000 nm is used. The measurement light emitted from the light emitting unit 125 is reflected by the half mirror 126 and enters the optical filter 122. The optical filter 122 has a band-pass filter characteristic that selectively transmits the wavelength band of the measurement light. The optical filter 122 is disposed in order to improve the S / N ratio of the reflected light from the eye to be detected detected by the light receiving unit 127.

  The measurement light emitted from the light emitting unit 125 is reflected by the half mirror 126 and irradiated to the eye to be examined through the optical filter 122 and the light transmitting member 124 (see FIG. 1). The measurement light reflected on the surface of the eyeball of the eye to be examined returns to the half mirror 126 as measurement reflected light, passes therethrough, and reaches the light receiving unit 127. The light receiving unit 127 includes a light detection element such as a photodiode, and the measurement reflected light is converted into an electric signal (applanation signal) there. The applanation signal output from the light receiving unit 125 is sent to the applanation signal detection unit 303 of the control system of FIG.

(basic action)
In the measurement of intraocular pressure of the eye to be examined using the ophthalmologic apparatus 100, the pump 110 is operated in a state where measurement light is irradiated from the optical system 123 to the eye to be examined. When the pump 110 operates, the pressure in the chamber chamber 120 increases. Accordingly, air is ejected from the nozzle 121 to the eye to be examined. As the pressure in the chamber 120 increases, the wind pressure of the airflow blown to the eye to be examined increases, and the surface shape of the eyeball of the eye to be examined is deformed from a convex state to a flat state by this wind pressure.

  As the surface shape of the eyeball of the subject's eye approaches flat, the surface shape of the eyeball of the subject's eye approaches the vertical plane with respect to the measurement light, and the reflected light is reflected in the same direction, so that the amount of measurement reflected light increases. Then, when the eyeball surface of the eye to be examined becomes almost flat, the amount of measurement reflected light becomes maximum. Thereafter, when the wind pressure blown to the eye to be examined is further increased, the surface of the eyeball is depressed by the wind pressure, so that the reflected directions of the reflected light are not aligned, and the amount of the measured reflected light is reduced.

  In this way, as shown in FIG. 4, the relationship between the pressure signal indicating the pressure in the chamber 120 and the applanation signal indicating the amount of reflected light from the eyeball surface of the eye to be examined is obtained. The intraocular pressure of the eye to be examined is obtained by multiplying the value of the pressure in the chamber chamber 120 at the time when the peak of the applanation signal is obtained by a correction coefficient.

  Note that the pressure signal 1 in FIG. 4 is a waveform when the on-off valve 141 is not closed when the peak of the applanation signal is detected. The pressure signal 2 is a waveform when the on-off valve 141 is closed when the peak of the applanation signal is detected.

(Control system)
FIG. 3 shows a control system 300 of the ophthalmologic apparatus 100. The control system 300 has a function as a computer. The control system 300 is configured using a dedicated or general-purpose electronic circuit. It is also possible to install software for executing the functions shown in FIG. 3 on a commercially available PC (personal computer) and configure the control system 300 using the PC.

  The control system 300 includes a processing operation control unit 301, a light emission control unit 302, an applanation signal detection unit 303, a chamber chamber pressure detection unit 304, a valve control unit 305, a valve opening / closing timing determination unit 306, a pump control unit 307, and a storage unit 308. The intraocular pressure calculation unit 309 is provided.

  The processing operation control unit 301 controls operations of the ophthalmic apparatus 100 and the control system 300. In particular, the processing operation control unit 301 controls execution of processing shown in FIGS. 5 and 6 to be described later. The light emission control unit 302 controls the light emission operation of the light emitting unit 125 of FIG.

  The applanation signal detection unit 303 receives the output of the light receiving element of the light receiving unit 127 in FIG. 2 and detects the applanation signal. FIG. 4 shows an example of the applanation signal. FIG. 4 shows the waveforms of the applanation signal and the pressure signal. The applanation signal is an output waveform of the light receiving unit 127. The pressure signal is an output waveform of the pressure sensor 132 that detects the internal pressure of the chamber chamber 120.

  The chamber chamber pressure detector 304 detects the internal pressure of the chamber chamber 120 based on the output of the pressure sensor 132. The valve control unit 305 sends a control signal to the valve driving device 142 to control the opening / closing operation of the opening / closing valve 141. The valve opening / closing timing determination unit 306 determines to determine the timing for opening / closing the opening / closing valve 141, particularly the timing for shifting from the open state to the closed state.

  The pump control unit 307 controls the operation of the pump 110. The storage unit 308 stores data, programs, measurement data (intraocular pressure data of the eye to be examined) necessary for the operation of the ophthalmic apparatus 100, and other data obtained in the course of the operation.

Ocular pressure calculating unit 309 calculates the detection IOP value based on the value of the pressure signal (the value of the pressure chamber chamber 120) at time t _g. Time t _g, the time position of the center of gravity of the applanation signal, in this case, employing the time of the peak of the applanation signal. In this process, the relationship between the value of the pressure signal at the peak of the applanation signal and the pressure in the eyeball is obtained in advance using the ideal model eye, and the correction coefficient is obtained in advance. In actual measurement, the intraocular pressure value is calculated by multiplying the value of the pressure signal at the time when the applanation signal reaches a peak by a correction coefficient. This processing is performed by the intraocular pressure calculation unit 309.

(Valve open / close control)
Hereinafter, processing performed by the valve opening / closing timing determination unit 306 will be described. As described above, the intraocular pressure value is calculated based on the pressure in the chamber chamber 120 at the time when the peak of the applanation signal is obtained. Therefore, it is not necessary to blow air onto the eye after the peak of the applanation signal is obtained. On the other hand, since the subject may feel uncomfortable when the air is blown to the eye to be examined, it is preferable that the air is blown to the eye to be examined to the minimum necessary.

  Therefore, the valve opening / closing timing determination unit 306 determines whether or not the peak of the applanation signal has been detected, and outputs a valve closing instruction signal. This valve closing instruction signal is sent to the valve control unit 305, and the operation of the open / close valve 141 from the open state to the closed state is executed. The peak of the applanation signal is detected as the time when the time derivative (tangential slope) of the waveform of the applanation signal is calculated and the value becomes zero.

  By doing so, it is possible to suppress the air injection to the eye to be examined which is unnecessary for the measurement of intraocular pressure, and to relieve the discomfort felt by the subject.

(Example of processing)
FIG. 5 shows an example of a processing procedure performed in the control system 300. An operation program for executing the processing shown in FIG. 5 is stored in the storage unit 308 and executed by the processing operation control unit 301. The operation program may be stored in an appropriate storage medium and provided from there.

  When the process is started, the pump 110 is driven with the open / close valve 141 opened (step S101). When the pump 110 starts to move, the pressure in the chamber chamber 120 starts to rise, and the output of the pressure signal illustrated in FIG. 4 is started. As the pressure in the chamber 120 increases, the output level of the pressure signal gradually increases, and an applanation signal is obtained at a certain stage.

  The valve opening / closing timing determination unit 306 monitors the time differential value of the applanation signal detected by the applanation signal detection unit 303, and determines whether or not the peak of the applanation signal has been obtained (step S102). When the applanation signal peak is obtained, a process for closing the on-off valve 141 is performed (step S103). Simultaneously with the execution of step S103, the pressure in the pressurizing chamber 116 is reduced by retracting the piston 112 (step S104). At this time, air flows from the intake chamber 118 into the pressurization chamber 116 when the pressurization chamber 116 becomes less than atmospheric pressure.

  Next, based on the value of the pressure signal at the time when the peak of the applanation signal acquired in step S103 is obtained (pressure in the chamber chamber 120), the intraocular pressure is calculated by the intraocular pressure calculation unit 309 (step S105), and processing Exit.

(Superiority)
According to the above processing, the burden on the subject due to the blowing of high-pressure air to the eye to be examined can be reduced in a state in which the measurement of the intraocular pressure of the eye to be examined is not hindered. According to this mode of operation, closing of the on-off valve 141 is performed in the process of increasing the internal pressure before the internal pressure of the chamber chamber 120 is fully increased (before reaching the peak value), so the waveform of the pressure signal 2 in FIG. The peak of the internal pressure of the chamber chamber 120 as seen in FIG.

When the on-off valve 141 is not closed, as shown in the pressure waveform 1, the internal pressure of the chamber chamber 120 continues to rise even after the peak of the applanation signal is obtained, and the ejection of high-pressure air from the nozzle 121 continues accordingly. To do. In addition, since the high-pressure air ejected from the nozzle 121 at this time has a higher pressure than the time t _g , the burden on the subject is large.

  The pump is not limited to the illustrated piston type pump, and the pump does not stop suddenly and operates by inertia even after the stop instruction is issued, and the pumping is continued. In the above processing, the pressurization chamber 116 and the chamber chamber 120 are shut off by the on-off valve 141 even if the pumping is continued. Therefore, after the on-off valve 141 is closed, the pump 110 is added due to inertia. Even if pressurization of the pressure chamber 116 occurs, the influence does not reach the chamber chamber 120. For this reason, after the opening / closing valve 141 is closed, the air only escapes from the chamber chamber 120, and the pressure in the chamber chamber 120 cannot increase.

  If the internal pressure is released from the chamber chamber 120 to the outside, even if the pump is stopped, the effect of pressurization performed by inertia is applied to the chamber chamber 120. For this reason, it is difficult to suppress an increase in the pressure inside the chamber 120 after the opening operation. In this regard, the form in which the on-off valve 141 is closed has an advantage that the pressure inside the chamber chamber 120 does not increase in principle after the on-off valve 141 is closed.

2. Second Embodiment In the first embodiment, a configuration in which an applanation signal peak time prediction unit is provided is also possible. In this case, the applanation signal peak time prediction unit predicts in advance the time at which the applanation signal peaks. This prediction is made based on the waveform shape of the applanation signal.

  For example, the relationship between the waveform shape of the applanation signal and the peak time of the waveform is analyzed using a plurality of model eyes set in various states, and an index for predicting the peak time of the applanation signal is acquired in advance. In addition, the peak time of the applanation signal is predicted from this index.

  A specific example will be described below. As illustrated in FIG. 4, the applanation signal rises gently at first, gradually becomes steeper, then rises linearly, and finally, the slope becomes smaller and reaches a peak. Therefore, the end point of the linear portion is detected from the change in the slope of the waveform (change in the time differential value), and the time when the peak of the applanation signal is obtained is predicted. As another method, it is possible to predict the time when the peak of the applanation signal is obtained from the slope of the straight line portion.

  Hereinafter, an example of a mode for predicting the time when the peak of the applanation signal is obtained will be described. FIG. 6 shows an example of processing. In this process, the driving of the pump 110 is started with the open / close valve 141 opened (step S201), and when the applanation signal is obtained, the peak time of the applanation signal is predicted by the method described above (step S202). ).

  Here, there are individual differences in the eye to be examined, and when there is a disease, the applanation signal may not necessarily have an assumed waveform because it may be different from the model eye. Therefore, the peak time (position on the time axis) may not be produced from the applanation signal waveform. In preparation for this case, an upper limit is set for the processing time, and it is determined whether or not the peak time of the applanation signal has been calculated within the specified time (step S203). In addition, since the waveform of the applanation signal usually falls within a certain range, if a value that is clearly inappropriate (an index for evaluating the waveform) is calculated, the determination in step S203 is NO.

In step S203, when the time t at which the applanation signal peaks is obtained (step S204), the opening / closing valve 141 is closed at the stage before time t (step S205). In this case, assuming that the time when the time t can be predicted is t ₀ , and the time when the opening / closing valve 141 starts to close is t ₁ , the relationship of t ₀ ≦ t ₁ <t is satisfied.

  On the other hand, when the peak time of the applanation signal cannot be calculated within the specified time or a value determined to be inappropriate (a value outside the expected range) is calculated in step S203, step S206 is performed. Proceed to In step S206, the peak of the actual applanation signal is detected as in the process of FIG. 5, and when the peak is detected, the on-off valve 141 is closed (step S207).

  Simultaneously with (or after) step S205 or step S207, pressure reduction processing of the pump 110 (retraction of the cylinder 112) is performed (step S208), and the peak time of the applanation signal predicted earlier (or in step S206). The intraocular pressure is calculated based on the pressure in the chamber 120 at the determined peak time (step S209), and the process is terminated.

(Superiority)
The mode in which the applanation signal peak is predicted and the valve closing process is started before that time is compared with the mode in which the on-off valve 141 is closed after the applanation signal peak is actually detected. The closing timing of the valve 141 can be advanced, and the burden on the eye to be examined can be further suppressed.

  If for some reason the peak time of the applanation signal cannot be predicted, or if the predicted value is not appropriate, the opening / closing valve 141 is closed when the applanation signal peak is detected. A case where the condition of the eye to be examined is not assumed can be dealt with.

4). Others The pump is not limited to the cylinder type. Further, it is possible to pressurize the pressurizing chamber 116 with the open / close valve 141 closed, and then open the open / close valve 141 to increase the internal pressure of the chamber chamber 120 to inject high pressure air from the nozzle 121 to the eye to be examined. It is. Also in this case, the opening / closing valve 141 is closed based on the applanation signal to reduce the burden on the eye to be examined. Further, it is possible to control the timing for closing the on-off valve 141 and to control the speed at which the on-off valve 141 is closed.

  DESCRIPTION OF SYMBOLS 100 ... Ophthalmologic apparatus 110 ... Pump, 111 ... Cylinder, 112 ... Piston, 113 ... Drive rod, 114 ... Drive device, 115 ... Intake hole, 116 ... Pressurization chamber, 117 ... Non-reversible valve, 118 ... Intake chamber, 120 DESCRIPTION OF SYMBOLS ... Chamber chamber, 121 ... Nozzle, 122 ... Optical filter, 123 ... Optical system, 124 ... Light transmissive member, 125 ... Issuing unit, 126 ... Half mirror, 127 ... Light receiving unit, 141 ... Opening / closing valve, 142 ... Driving device .

Claims (7)

A chamber room for storing air to be sprayed on the eye to be examined;
A pump for pressurizing the chamber chamber;
An on-off valve disposed between the chamber chamber and the pump;
An optical system for irradiating the eye to be examined with measurement light and detecting reflected light from the eye to be examined, and
High-pressure air is blown onto the eye to be examined by pressurizing the chamber chamber with the pump with the on-off valve opened.
An ophthalmologic apparatus in which the on-off valve is closed based on the amount of reflected light.   The ophthalmologic apparatus according to claim 1, wherein the on-off valve is closed based on a time t when the amount of the reflected light becomes maximum.   The ophthalmologic apparatus according to claim 2, wherein the on-off valve is closed after time t when the amount of the reflected light becomes maximum.   The ophthalmologic apparatus according to claim 2 or 3, wherein the time t is predicted based on a detection signal of the reflected light. When the time when the time t can be predicted is t ₀ and the time when the on-off valve starts to close is t ₁ ,
The ophthalmic apparatus according to claim 4, wherein t ₀ ≦ t ₁ <t.   The ophthalmic apparatus according to any one of claims 1 to 5, wherein the closing of the on-off valve is performed in a process in which an internal pressure of the chamber chamber is increasing.   The ophthalmologic apparatus according to claim 1, wherein the pressure in the chamber chamber does not increase after the on-off valve is closed.

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