JP2009268651A - Non-contact ultrasonic tonometer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily achieve the alignment for an examined eye. <P>SOLUTION: The tonometer includes: a probe having an oscillator for applying ultrasonic waves to the examined eye and a vibration detecting sensor for detecting the reflection waves from the examined eye; and an anterior eye part observing optical system with the probe disposed in an observation light path for observing the anterior eye part of the examined eye for forming the image of the anterior eye part via a peripheral area of the probe. The incident waves output from the oscillator and the reflection waves detected by the vibration detection sensor are compared, and the ocular tension of the examined eye is measured by the arithmetic operation process. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a non-contact ultrasonic tonometer that measures intraocular pressure of a subject's eye in a non-contact manner using ultrasonic waves.

  As a device that measures the intraocular pressure of the subject eye by comparing the incident wave incident on the subject eye and the reflected wave from the subject eye, the transducer that detects vibration and the reflected wave from the subject eye is detected. Holding a probe having a vibration detection sensor, and having a probe pen having an elastic cap whose tip is in contact with the eyeball, and adjusting the intraocular pressure of the eye to be examined while the elastic cap is in contact with the eye to be examined A contact-type intraocular pressure inspection apparatus for measuring has been proposed (see Patent Document 1).

In addition, as a non-contact type configuration, a probe having a transducer that inputs ultrasonic waves to the eye to be examined (however, a model eye) and a vibration detection sensor that detects a reflected wave from the eye to be examined is provided. There has been proposed an intraocular pressure inspection apparatus that measures the intraocular pressure of an eye to be examined in a non-contact manner with a probe disposed in front of the eye to be examined (see Non-Patent Document 1). In this case, the phase change is measured as a frequency change amount, and the correlation between the frequency change amount and the hardness of the eyeball model is obtained.
JP 2004-269299 A Masayuki Kamide and three others, “Fundamental research on non-contact type intraocular pressure measurement system using ultrasonic phase shift method”, IEICE technical report Sensor Micromachine Division, 2007, p. 93-96

  However, in the case of the configuration of Patent Document 1, the intraocular pressure measurement is performed in a state where the probe pen is in contact with the eye to be examined, and the burden on the eye to be examined is large. Further, in the case of the configuration of Non-Patent Document 1, it is only assumed to be measured for a model eye, and is still insufficient for measuring an actual human eye, and there are many problems for practical use. For example, in the case of the human eye, the eye moves due to microscopic eye movements or movement of the line of sight of the subject's eye, so the characteristics of the reflected wave detected by the vibration detection sensor (e.g. (Frequency, phase, etc.) may change, resulting in variations in measurement results.

  In view of the above-described prior art, an object of the present invention is to provide a non-contact ultrasonic tonometer that can easily perform alignment on an eye to be examined.

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

(1) a probe having a transducer for causing ultrasonic waves to enter the eye to be examined, and a vibration detection sensor for detecting a reflected wave from the eye to be examined;
An anterior ocular segment observation optical system in which the probe is arranged in an observation optical path for observing the anterior segment of the eye to be examined and forms an anterior ocular segment image through a peripheral region of the probe; ,
An incident wave emitted from the vibrator and a reflected wave detected by the vibration detection sensor are compared, and the intraocular pressure of the eye to be examined is measured by a calculation process.
(2) In the non-contact ultrasonic tonometer of (1),
The probe is arranged on an observation optical axis of an anterior ocular segment observation optical system.
(3) In the non-contact ultrasonic tonometer of (2),
The probe is arranged such that the central axis of the probe and the observation optical axis of the anterior ocular segment observation optical system are coaxial.
(4) In the non-contact ultrasonic tonometer of (2),
The anterior ocular segment observation optical system is provided with an imaging element for observing the anterior ocular segment and an objective lens for guiding the anterior segment image of the eye to be examined onto the imaging element. To do.
(5) In the non-contact ultrasonic tonometer of (4),
The objective lens of the anterior ocular segment observation optical system is arranged behind or substantially at the same position as the probe.
(6) In the non-contact ultrasonic tonometer of (4),
An insertion hole into which the probe is inserted is formed in the objective lens of the anterior ocular segment observation optical system.
(7) In the non-contact ultrasonic tonometer of (4),
The objective lens of the anterior ocular segment observation optical system is disposed in front of the probe, and an opening is formed in a portion corresponding to an ultrasonic wave propagation path by the probe. .
(8) The non-contact ultrasonic tonometer of (2)
A fixation target projection optical system that has a fixation light source for fixation target projection and projects a fixation target for fixing the eye to be examined toward the eye;
The center of the probe is provided with an opening for passing a fixation target projection light beam emitted from the fixation light source, or the fixation light source.
(9) The non-contact ultrasonic tonometer of (2)
An index projection optical system having an alignment light source for projecting an alignment index and projecting the alignment index toward the anterior segment of the eye to be examined;
The observation optical system forms an image of the cornea reflected by the alignment light source and an anterior ocular segment image to be examined on the two-dimensional image sensor through a peripheral region of the probe.
(10) In the non-contact ultrasonic tonometer of (9), an opening for passing the alignment light beam emitted from the alignment light source is formed at the center of the probe. And

  According to the present invention, alignment with respect to an eye to be examined can be easily performed.

  An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an external configuration diagram of a non-contact ultrasonic tonometer according to the present embodiment. The non-contact ultrasonic tonometer 100 is a so-called stationary non-contact ultrasonic tonometer, and is movable on the base 1, the face support unit 2 attached to the base 1, and the base 1. And a measuring unit (measuring unit) 4 that is movably provided on the moving table 3 and houses a measurement system and an optical system, which will be described later. The measuring unit 4 is moved in the left and right direction (X direction), the up and down direction (Y direction), and the front and rear direction (Z direction) with respect to the eye E by an XYZ driving unit 6 provided on the moving table 3. The movable table 3 is moved in the X direction and the Z direction on the base 1 by operating the joystick 5. Further, when the examiner rotates the rotary knob 5 a, the measurement unit 4 is moved in the Y direction by the Y drive of the XYZ drive unit 6. On the top of the joystick 5, a measurement start switch 5b is provided. A display monitor 72 is provided on the movable table 3.

  FIG. 2 is a diagram for explaining a measurement system and an optical system of the non-contact ultrasonic tonometer according to the present embodiment, and is a specific example when a probe is arranged in the observation optical path. FIG. 3 is a diagram for explaining a control system of the non-contact ultrasonic tonometer according to the present embodiment.

  A probe (transducer) 10 disposed in front of the eye E to be examined E includes a vibrator 11 for causing ultrasonic waves to enter the eye to be examined, a vibration detection sensor 13 for detecting a reflected wave from the eye to be examined, And is used to measure the intraocular pressure of the eye to be examined in a non-contact manner. The probe 10 has, for example, a structure in which two piezoelectric elements are stacked, one of which is used as the vibrator 11 and the other is used as the vibration detection sensor 13. In the present embodiment, a pulse wave is used as the ultrasonic wave incident on the eye to be examined, the vibrator 11 is an ultrasonic wave incident unit for causing the ultrasonic pulse to be incident on the eye to be examined, and the vibration detection sensor 13 is the wave to be measured. It is used as an ultrasonic receiving unit that receives a reflected wave by an ultrasonic pulse incident on the optometry.

  Further, an acoustic lens 16 for converging the ultrasonic wave emitted from the transducer 11 is provided on the eye side of the probe 10 so that the alignment between the eye to be examined and the probe 10 is appropriate. Sometimes, the eye to be examined is in focus.

  Here, the probe 10 is sequentially connected to an amplifier 81, a frequency component analyzing unit 82, a frequency phase difference specifying unit 83, and a control unit 70 (see FIG. 3). The electrical signals corresponding to the incident wave and the reflected wave are amplified to an appropriate signal level by the amplifier 81, and the frequency component analysis of the incident wave and the reflected wave is performed by the frequency component analyzing unit 82. A spectral distribution of the phase difference with respect to the frequency is obtained for each.

  Next, the frequency phase difference specifying unit 83 compares the spectrum distribution of the incident wave and the spectrum distribution of the reflected wave, and the phase difference θx that is the difference between the phase of the incident wave and the phase of the reflected wave at each frequency fx is obtained. Sought and specified. Here, since the phase difference θx at the frequency fx changes according to the intraocular pressure of the eye to be examined (strictly speaking, the change in the hardness of the cornea due to the change in the intraocular pressure), the control unit 80 has the frequency phase difference specifying unit 83. The phase difference θx is detected based on the output signal, and the intraocular pressure value of the eye to be examined is obtained based on the detection result. For the hardness detection method using the ultrasonic pulse method described above, refer to Japanese Patent Application Laid-Open No. 2002-272743.

  Returning to the description of FIG. A light beam for projecting a fixation target emitted from a fixation light source 32 (described later) and a light flux for projecting an alignment index emitted from an alignment light source 42 pass through the center of the probe 10 and the acoustic lens 16. An opening 18 (for example, a circular hole having a diameter of about 1 mm) is formed.

  Further, the vibrator 11 and the vibration detection sensor 13 arranged at the center of the objective lens 22, and a circuit system (amplification circuit 81, frequency component analysis unit 82, frequency arranged at a position off the optical path of the observation optical system 20). The phase difference specifying unit 83, the control unit 70, and the like are electrically connected by a wiring cable 95. In this case, since the wiring cable 95 is disposed in the observation optical path of the observation optical system 20, the anterior ocular segment reflected light is irregularly reflected on the surface of the wiring cable 95, and noise light is generated on the two-dimensional image sensor 26 described later. May be detected. Accordingly, the noise light is reduced by covering the wiring cable 95 with the cover 96 (anterior eye reflection light absorbing member) coated with a characteristic of absorbing the anterior eye reflection light (for example, infrared light). The anterior ocular segment observation light can be observed.

  Next, the configuration of the optical system will be described. In this optical system, an observation optical system 20 for observing the anterior segment of the subject's eye, a fixation target projection optical system 30 for fixing the subject's eye, and an index for XY alignment on the subject's eye cornea. A first index projection optical system 40 for projecting, an index projection optical system 50 for projecting an index for alignment detection in the working distance direction onto the eye cornea, and an index for alignment detection in the working distance direction projected onto the eye cornea A distance index detection optical system 55 is provided for detecting.

  In the observation optical system 20, the probe 10 is disposed in the observation optical path, and an anterior ocular segment image is formed through the peripheral region of the probe 10. More specifically, the observation optical system 20 includes an objective lens 22, an imaging lens 24, a filter 25, and a two-dimensional image sensor 26, and the probe 10 is disposed on the observation optical axis L1. . For this reason, when the observation optical axis L1 is aligned with a predetermined part (for example, the center of the cornea and the center of the pupil) of the eye to be examined, the probe 10 is disposed in front of the eye to be examined. Further, in the configuration shown in FIG. 2, since the central axis of the probe 10 (extension line of the central axis) and the observation optical axis L1 are arranged coaxially, the observation light is applied to a predetermined part of the eye to be examined. When the axis L1 is aligned, the center axis of the probe 10 (extended line of the center axis) and the predetermined part of the eye to be inspected coincide with each other, so that reflected waves from the eye to be inspected by ultrasound can be efficiently acquired. .

  An anterior ocular segment illumination light source 38 for illuminating the subject eye with infrared light is disposed obliquely in front of the subject eye. The filter 25 transmits light from the light source 38 and a light source 42 to be described later, and has an opaque characteristic to light from a light source 51 for detecting a working distance to be described later.

  Here, the anterior ocular segment reflected light from the anterior ocular segment illumination light source 38 travels toward the objective lens 22. In this case, the anterior ocular segment reflected light that has reached the peripheral region of the probe 10 passes through the objective lens 22 and passes through the beam splitter 36 and the beam splitter 46 to the two-dimensional imaging device 26 by the imaging lens 24. Imaged.

  In the above configuration, the two-dimensional image sensor 26 is used as an image sensor for anterior segment observation. Then, the imaging signal output from the two-dimensional imaging device 26 is input to the control unit 70 and displayed on the screen of the display monitor 72. The imaging optical system including the objective lens 22 and the imaging lens 24 is used as a light guide member that guides the anterior eye image of the eye to be examined to the two-dimensional imaging device 26. In the present embodiment, the anterior eye image of the eye to be examined is guided onto the two-dimensional imaging device 26 by a lens system including a plurality of lenses, but the anterior eye image of the eye to be examined is two images by one objective lens. A configuration in which light is guided onto the two-dimensional image sensor 26 may be used.

  Further, with respect to the positional relationship between the objective lens 22 and the probe 10 in the observation optical axis L1 direction (Z direction), the objective lens 22 is arranged behind the probe 10 (on the image sensor 26 side) or at the same position. Thus, it is possible to secure a wide space between the eye to be examined and the apparatus housing (see FIGS. 2 and 5). In this case, since the anterior ocular segment reflected light may be blocked by the probe 10 and the acoustic lens 16, in order to observe a bright anterior ocular segment image, the objective lens 22 and the probe 10 must be connected to the observation optical axis. It is preferable to arrange them at close positions in the L1 direction, more preferably at substantially the same position in the observation optical axis L1 direction.

  As a specific configuration in which the objective lens 22 is arranged at the same position with respect to the probe 10, a configuration as shown in FIG. An insertion hole 22a into which the probe 10 is inserted is formed in the objective lens 22, and the probe 10 is attached to the objective lens 22 through the insertion hole 22a.

  Further, as a specific configuration in which the objective lens 22 is arranged behind the probe 10, a configuration as shown in FIG. 5 is conceivable. In this case, the objective lens 22 is formed with an insertion hole 22a into which the support member 19 that supports the probe 10 and the acoustic lens 16 is inserted, and the probe is inserted by inserting the support member 19 into the insertion hole 22a. The touch element 10 and the acoustic lens 16 are supported at predetermined positions.

  Moreover, it is not restricted to the said structure, You may make it arrange | position an objective lens ahead of a probe. In this case, in order to prevent the ultrasonic wave emitted from the transducer from being reflected and attenuated by the objective lens, the objective lens has an opening at a portion corresponding to the ultrasonic wave propagation path by the probe. Preferably it is. Thereby, the ultrasonic wave emitted from the vibrator enters the eye to be examined through the opening, and the reflected wave from the eye to be examined is detected by the vibration detection sensor through the opening.

  Returning to the description of FIG. The fixation target projection optical system 30 has at least a fixation light source for fixation target projection, and projects a fixation target for fixing the eye to be examined toward the eye to be examined. More specifically, the fixation target projection optical system 30 includes a fixation light source 32 that emits visible light, a fixation target 33, an aperture stop 34, a projection lens 35, a beam splitter 46, and a beam splitter 36. Then, the fixation target is projected onto the eye to be examined through the opening 18 formed in the probe 10 and the acoustic lens 16. The projection optical axis L2 of the fixation target projection optical system 30 is coaxial with the observation optical axis L1 by the beam splitter 46 disposed in the optical path of the observation optical system 20.

  Here, the light from the fixation target 33 emitted from the light beam for projecting the fixation target emitted from the light source 32 passes through the projection lens 35 after the diameter of the light beam is reduced by the aperture stop 34, and then the beam splitter. After being reflected by 46, it passes through the beam splitter 36 and the opening 18 toward the eye to be examined and is projected onto the fundus of the eye to be examined. Thereby, fixation of the eye to be examined is performed.

  The first index projection optical system 40 includes at least an alignment light source for alignment index projection, and projects the alignment index from the front direction toward the anterior eye portion to be examined. More specifically, the first index projection optical system 40 includes an alignment light source 42 that emits infrared light, a projection lens 44, and a beam splitter 36, and the opening 18 formed in the probe 10. An XY alignment index is projected onto the eye cornea through the eye. Further, the projection optical axis L3 of the alignment index projection optical system 40 is coaxial with the observation optical axis L1 by the beam splitter 36 disposed in the optical path of the observation optical system 20.

  Here, the alignment light beam emitted from the light source 42 passes through the projection lens 44, is reflected by the beam splitter 36, and is then applied to the eye cornea through the opening 18. Then, an index i1 (alignment index image) that is a virtual image of the light source 42 is formed by the alignment light flux specularly reflected by the cornea Ec.

  Then, the light beam from the index i1 travels toward the objective lens 22. In this case, the alignment reflected light that has reached the peripheral region of the probe 10 passes through the objective lens 22, passes through the beam splitter 36 and the beam splitter 46, and is formed on the two-dimensional imaging device 26 by the imaging lens 24. Imaged. That is, the cornea reflection image i1 from the alignment light source 42 and the anterior eye image of the eye to be inspected by the anterior segment illumination light source 38 are formed on the two-dimensional image sensor 26 via the peripheral region of the probe 10. As a result, the anterior segment image and the corneal bright spot image (alignment index image) are received on the two-dimensional image sensor 26. Note that the alignment index image received by the two-dimensional image sensor 26 moves from the two-dimensional image sensor 26 because the index i1 moves on the two-dimensional image sensor 26 when the eye E (cornea Ec) moves in the XY direction. Based on this detection signal, the alignment state of the probe 10 relative to the eye E in the XY directions can be detected.

  As described above, the alignment light beam is irradiated through the opening 18 formed in the probe 10 and the acoustic lens 16, and the reflected light beam from the index i1 is two-dimensionally imaged through the peripheral region of the probe 10. When the light is received by the element 26, there is a high possibility that the reflected light beam is scattered by the acoustic lens 16. Therefore, as shown in FIG. 2, the first index projection optical system 40 once collects the alignment light beam applied to the eye to be examined before reaching the eye to be examined and irradiates the eye cornea as a divergent light beam. Such an optical system is preferable. In this way, the light beam from the index i1 becomes a light beam that can efficiently bypass the peripheral area of the probe 10, and can be used as an alignment light beam. On the other hand, when a convergent light beam or a parallel light beam is irradiated to the eye cornea to be examined, the reflection angle in the peripheral direction is small, and the reflected light beam from the index i1 is likely to be displaced by the acoustic lens 16.

  The working distance index projection optical system 50 has an infrared light source 51 and a projection lens 52 for alignment detection in the Z direction (front-rear direction), and displays an index for alignment detection in the working distance (Z) direction on the eye cornea. Project to. Note that the projection optical axis L4 of the projection optical system 50 intersects the observation optical axis L1 at a predetermined angle. Here, the light from the light source 51 is converted into a substantially parallel light beam by the projection lens 52, and then projected from the oblique direction onto the cornea of the eye along the projection optical axis L 4, and the light beam specularly reflected by the cornea Ec is a virtual image of the light source 51. An index i2 is formed.

  The working distance index detection optical system 55 includes a light receiving lens 56, a filter 57, and a position detection element 58 (for example, a line CCD), and detects an alignment index image formed by the distance index projection optical system 50. The filter 57 transmits light from the light source 51 and has a characteristic that does not transmit light from the light sources 38 and 42. The projection optical axis L5 of the working distance index detection optical system 55 and the projection optical axis L4 of the working distance index projection optical system 50 have an axis symmetrical to the observation optical axis L1, and the optical axis L5 is an optical axis L4 and a light beam. Cross on axis L1. Here, the light beam from the index i <b> 2 is imaged on the position detection element 58 via the filter 57 by the light receiving lens 56. When the eye E (cornea Ec) moves in the Z direction, the index i2 moves on the position detection element 58. Therefore, the probe 10 is aligned with the eye E in the Z direction based on the detection signal from the position detection element 58. The state can be detected.

  Next, the configuration of the control system will be described with reference to FIG. The control unit 70 includes a frequency phase difference specifying unit 83, a light source 32, a light source 42, a light source 51, a two-dimensional image sensor 26, a position detection element 58, a light source 38, a display monitor 72, a memory 75 as a storage unit, a rotary knob 5a, The measurement start switch 5b, a control unit 74 provided with various switches, the XYZ drive unit 6, and the like are connected to perform overall control of the apparatus, calculation processing of measured values, and the like.

The memory 75 stores a table indicating the correlation between the phase difference θx at the frequency fx and the intraocular pressure value of the eye to be examined, and the control unit 70 outputs the phase difference output from the frequency phase difference specifying unit 83. The intraocular pressure value of the eye to be examined corresponding to θx is acquired by the memory 75, and the obtained intraocular pressure value is displayed on the display monitor 72.
The correlation between the phase difference θx and the intraocular pressure value of the eye to be examined is, for example, the correlation between the intraocular pressure value of the eye to be examined obtained by the Goldman tonometer and the phase difference θx acquired by this apparatus in advance. It can be set by finding it by experiment. The memory 75 stores a program for measuring the intraocular pressure of the subject's eye using the probe 10 and a control program for controlling the entire apparatus.

  The control unit 70 performs alignment detection in the XY directions based on the detection signal from the two-dimensional image sensor 26 and performs alignment detection in the Z direction based on the detection signal from the position detection element 58. The control unit 74 includes a selection switch 74a for selecting an automatic alignment mode for automatically aligning the measuring unit 4 with respect to the eye to be examined and a manual alignment mode for manually aligning the measuring unit 4 with respect to the eye to be examined. A selection switch 74b for selecting an auto shot mode for automatically issuing a measurement start trigger when alignment is completed and a manual shot mode for generating a measurement start trigger based on an operation signal from the measurement start switch 5b are arranged. Yes. When the auto-shot mode is set, the control unit 70 determines the suitability of the alignment state based on the detection results from the two-dimensional imaging device 26 and the position detection device 58, and the determination result is On the basis of this, a trigger signal for starting measurement is generated, and based on the generation of the trigger signal, the probe 10 emits an ultrasonic wave toward the eye to be examined.

  In addition, the control unit 70 notifies the examiner of the mode selected by the examiner. For example, the selected mode is displayed on the monitor 72 or the selected mode is notified by voice.

  The operation of the apparatus having the above configuration will be described. First, the examiner fixes the subject's face to the face support unit 2 and then aligns the subject's eye with the joystick 5 while viewing the display monitor 72. At this time, as shown in FIG. 4, the control unit 70 displays on the monitor 72 an anterior segment image acquired by the two-dimensional image sensor 26 and a reticle LT and an indicator G used for alignment with the eye to be examined. And display it.

  Here, when the index i1 image is formed on the display monitor 72, the two-dimensional image sensor 26 can detect the index i1, so that automatic alignment is possible in the vertical and horizontal directions. Further, when the light beam of the index i2 enters the position detection element 58, automatic alignment is possible in the Z direction. In this case, the control unit 70 controls the display of the indicator G based on the Z-direction alignment information obtained from the detection signal from the position detection element 58.

  Here, a case where the automatic alignment mode and the auto shot mode are selected will be described. The control unit 70 obtains the respective alignment deviation amounts in the vertical and horizontal directions and the front-rear direction with respect to the alignment position when the eye E is in an appropriate position, and each deviation amount is determined based on the deviation information. The XYZ drive unit 6 is driven and controlled so as to fall within the allowable range. When the alignment deviation amount falls within the allowable range, the control unit 70 stops driving the XYZ driving unit 6, automatically generates a trigger signal for starting measurement, and measures the intraocular pressure using the probe 10. To start. In the above configuration, automatic alignment control is performed in the XYZ directions, but automatic alignment control may be performed in at least one of the XYZ directions.

  A case where the manual alignment mode and the manual shot mode are selected will be described. In this case, the examiner operates the joystick 5 so that the index i1 image displayed on the monitor 72 enters the reticle LT and the indicator G indicates the completion of alignment (see FIG. 4B). When the alignment in each direction is completed in this way and the measurement start switch 5b is pressed by the examiner, the control unit 70 issues a measurement start trigger signal and starts tonometry using the probe 10. .

  When the trigger signal for starting measurement is generated (input) as described above, the control unit 70 causes the transducer 11 to emit an ultrasonic pulse toward the eye to be inspected based on the trigger signal. The reflected wave due to the ultrasonic pulse incident on the eye to be examined is detected using the vibration detection sensor 14. Then, as described above, the control unit 70 calculates the intraocular pressure value of the subject's eye based on the output signal from the frequency phase difference specifying unit 83 and displays the measurement result on the monitor 82.

  With the above configuration, it is possible to easily align the probe 10 and the eye to be examined.

  In the above description, the light beam for projecting the fixation target is projected onto the fundus of the subject's eye through the opening 18 formed at the center of the probe 10. However, the present invention is not limited to this. Instead of this, a fixation light beam may be projected onto the fundus of the eye to be examined through the peripheral region of the probe 10 in the objective lens 22. In this case, for example, a configuration in which a ring opening having a ring center on the optical axis L2 is used instead of the aperture stop 34 in which a spot opening is formed on the optical axis L2.

  In the above description, the alignment light beam is projected onto the fundus of the eye to be examined through the opening 18 formed in the center of the probe 10, but the present invention is not limited to this. The alignment cornea is irradiated with the alignment light beam through the peripheral region of the probe 10 in the objective lens 22, and the reflected light beam by the alignment light beam is transmitted through the peripheral region of the probe 10 in the objective lens 22. 26 may be configured to project and receive the alignment light flux by bypassing the probe 10. In this case, for example, the light source 42 may be used as a ring-shaped light source.

  FIG. 6 is a diagram showing a modification example of the fixation target projection optical system and the first alignment index projection optical system. In this case, a fixation light source 32 (for example, a visible LED) is provided at the center of the probe 10. In this case, the visible light beam emitted from the fixation light source 32 is projected onto the fundus of the eye to be examined, thereby fixing the eye to be examined.

  An index projection optical system 140 that projects an alignment index at a predetermined angle with respect to the observation optical axis L1 of the observation optical system 20 is disposed outside the objective lens 22, and a corneal reflection image by the index projection optical system 140 is a probe 10. Passed through the surrounding area. In this case, the angle of the projection optical axis of the index projection optical system 140 with respect to the observation optical axis L1 may be set so that the vignetting of the corneal reflected light beam by the acoustic lens 16 is reduced. In the case where the fixation light source 32 is arranged at the center of the probe 10 as shown in FIG. 6, a light source that emits visible light and near infrared light is used as the fixation light source 32, and the fixation light source 32 is used. The fixation light source 32 may also be used as an alignment light source by causing the imaging device 26 for observing the anterior eye part to receive a cornea reflection image of near infrared light emitted from the visual light source 32.

  In the above description, the probe 10 is arranged on the observation optical axis L1. However, the configuration is not limited to this, and as shown in FIG. 7, the probe is observed from the observation optical axis L1 in the XY directions. A configuration in which the child 10 is detached may be used. In this case, the detection position of the corneal bright spot i1 on the two-dimensional image sensor 26 when the central axis of the probe 10 is aligned with the eye to be examined (for example, the center of the cornea and the center of the pupil) is set as the alignment reference position. Then, the display position of the reticle LT, the alignment completion position in the alignment detection, and the like may be set.

  FIG. 8 is a diagram for explaining the measurement system and the optical system of the non-contact ultrasonic tonometer according to the present embodiment, and a specific example when the probe 10 is arranged outside the observation optical path of the observation optical system 20. FIG. In FIG. 8, the same reference numerals as those in FIG. 2 denote the same functions unless otherwise specified.

  The ultrasonic reflecting member (acoustic mirror) 90 reflects the incident wave emitted from the vibrator 11 toward the eye to be examined, and reflects the reflected wave from the eye to be examined by the incident wave toward the vibration detection sensor 13. In the observation optical system 20, the probe 10 is arranged outside the observation optical path, and the observation optical axis L1 is formed on the ultrasonic propagation path between the ultrasonic reflection member 90 and the eye to be examined. Is provided. In addition, the objective lens 22 is formed with an opening 22b for allowing ultrasonic waves from the probe 10 to pass therethrough.

  Here, the ultrasonic wave emitted from the vibrator 11 is reflected by the ultrasonic reflecting member 90 and is incident on the eye to be examined through the opening 22 b formed in the objective lens 22. The reflected wave from the eye to be examined passes through the opening 22 b formed in the objective lens 22, is reflected by the ultrasonic reflecting member 90, and is detected by the vibration detection sensor 13.

  When the objective lens 22 is disposed between the ultrasonic reflecting member 90 and the eye to be inspected as shown in FIG. 8, the objective lens 22 is opened at a portion corresponding to the ultrasonic propagation path by the probe 10. Since the portion 22b is formed, attenuation that occurs when the ultrasonic wave passes through the objective lens 22 can be avoided. In this case, in order to prevent the anterior ocular segment reflected light from the light source 38 from being received by the two-dimensional imaging device 26 through the opening 22b and becoming noise light, an ultrasonic wave with a coating having a characteristic of cutting the observation light beam is applied. The reflection member 90 may be used.

  Further, in the ultrasonic reflection member 90, a member (for example, a colorless and transparent hard plastic plate) having characteristics of reflecting ultrasonic waves and transmitting light may be used as the ultrasonic reflection member 90. . Thereby, even if the ultrasonic reflection member 90 is arranged in the optical path of the fixation target projection optical system 30 and in the optical path of the alignment projection optical system 40, vignetting of the fixation light flux and the alignment light flux can be avoided. When the ultrasonic reflecting member 90 having optical transparency is used, in consideration of a change in optical path length due to light passing through the ultrasonic reflecting member, the optical path dividing member such as the beam splitter 36 and the beam splitter 46 is comparable. A member having an area may be used (see, for example, FIG. 9).

  In addition, the present invention is not limited to the above configuration, and by providing an opening in a part of the ultrasonic reflection member 90, the fixation light beam and the alignment light beam may pass through the opening and enter the eye to be examined. . In the above configuration, the case where the ultrasonic reflecting member 90 is disposed in the common optical path of the fixation target projection optical system 30 and the alignment projection optical system 40 has been described. Even when the ultrasonic reflecting member 90 is disposed in at least one of the optical paths of the optical system 40, the above configuration can be applied.

  Further, the configuration in which the probe 10 is disposed outside the observation optical path of the observation optical system 20 is not limited to the configuration in FIG. 8, and ultrasonic waves are provided between the objective lens 22 of the observation optical system 20 and the eye to be examined. A reflection member 90 may be provided. In this case, the ultrasonic wave emitted from the vibrator 11 is incident on the eye to be examined via the ultrasonic reflection member 90, and the reflected wave is detected by the vibration detection sensor 13 via the ultrasonic reflection member 90.

  In the above configuration, a measurement optical system that measures an eye characteristic different from the intraocular pressure of the eye to be examined may be provided so that other eye characteristics can be measured in addition to the eye pressure to be examined.

  FIG. 9 is a schematic optical diagram showing a specific example when an eye refractive power measurement optical system is provided in a non-contact ultrasonic tonometer.

  In FIG. 9, an eye refractive power measurement optical system 310 is provided as a measurement optical system. In the measurement optical system 310, the probe 10 is disposed outside the measurement optical path, and between the ultrasonic reflection member 90 and the eye to be examined. The measurement optical axis L6 is provided on the ultrasonic wave propagation path.

  More specifically, the ultrasonic reflection member 90 is disposed in front of the eye of the subject's eye, and the ultrasonic wave emitted from the vibrator 11 enters the subject's eye via the ultrasonic reflection member 90, and the reflected wave is an ultrasonic wave. It is detected by the vibration detection sensor 13 via the reflection member 90. Thereby, the intraocular pressure of the eye to be examined is measured.

  Further, an eye refractive power measurement optical system 310 is disposed on the transmitted light path O1 of the dichroic mirror 301 disposed behind the ultrasonic wave reflecting member 90. The measurement optical system 310 is an optical system that projects a measurement light beam onto the fundus and causes the light receiving element to receive a reflected light beam from the fundus of the subject's eye, and measures eye refractive power based on the output of the light receiving element. Since the measurement optical system 310 and its measurement principle can be known, the description thereof is omitted here.

  In the reflection direction of the dichroic mirror 301, an objective lens 3111 for observing the eye E, a dichroic mirror 312 and a total reflection mirror 313 are arranged. On the optical path O2 in the reflection direction of the mirror 313, a fixation target projection optical system (not shown) for fixing the fixation target to the eye E is arranged.

  The eye E is imaged on the optical path O3 in the reflection direction of the dichroic mirror 312 including the imaging lens 320 and a two-dimensional imaging device 321 such as an area CCD disposed at a position substantially conjugate with the vicinity of the anterior segment of the eye E. An observation optical system 322 for obtaining an eye image to be examined is arranged. Note that the two-dimensional imaging device 321 receives the anterior segment reflected light illuminated by the anterior segment illumination light source 325 and the alignment index image projected on the cornea by an alignment projection optical system (not shown).

  Note that the measurement optical axis L 6 of the measurement optical system 310 and the observation optical axis of the observation optical system 311 are made coaxial by the dichroic mirror 301. The dichroic mirror 301 transmits light having a wavelength emitted from a measurement light source included in the measurement optical system 310, and reflects light having a wavelength and visible light emitted from an anterior ocular segment illumination light source 325 and an alignment projection optical system (not shown). Has characteristics. The dichroic mirror 312 has a characteristic of transmitting visible light and reflecting infrared light. In addition, as the ultrasonic reflecting member 90, a member (for example, a colorless and transparent hard plastic plate) having characteristics of reflecting ultrasonic waves and transmitting light is used, and a measurement light beam by the measurement optical system 310 and a light source 325 are used. Is transmitted through the anterior eye part reflected light, a fixation light beam by a fixation target projection optical system (not shown), light emitted from an alignment projection optical system (not shown), and the like.

  In the configuration of FIG. 9, the ultrasonic reflecting member 90 is disposed in the common optical path of the measurement optical system 310, the observation optical system 322, and the fixation target projection optical system, but is emitted from the probe 10. The ultrasonic wave is not limited to this as long as the ultrasonic wave is emitted from the front to the eye to be examined via the ultrasonic reflection member 90. For example, a configuration in which the ultrasonic reflection member 90 is provided between the dichroic mirror 301 and the objective lens 311 can be considered.

  With the configuration as described above, in addition to measuring the intraocular pressure of the eye to be examined, the eye refractive power of the eye to be examined can be measured. Thereby, the structure of the ophthalmologic apparatus which can measure the eye characteristic different from the eye pressure to be examined and the eye pressure of the eye to be examined can be made compact.

  In the above description, the measurement of the eye refractive power has been described as an example, but the measurement optical system that measures the eye characteristics different from the intraocular pressure of the eye to be examined by receiving the reflected light from the measurement light irradiated to the eye to be examined. If so, it is not limited to this. In this case, instead of the ocular refractive power measurement optical system 310, a non-contact type ocular axial length measurement optical system (for example, Japanese Patent Application Laid-Open No. 2007-37284), a corneal thickness measurement optical system (for example, Japanese Patent Application Laid-Open No. 63-197433). , Etc. can be considered.

  In the above description, the continuous measurement mode and the normal measurement mode may be arbitrarily selected for the intraocular pressure measurement of the eye to be examined based on the measurement start trigger signal. In this case, for example, a normal measurement mode in which one intraocular pressure measurement is performed based on one trigger signal, and a continuous measurement mode in which a plurality of intraocular pressure measurements are continuously performed based on one trigger signal; It is conceivable to provide a selection switch for selecting.

  The case where the continuous measurement mode is selected will be described below. When a trigger signal for starting measurement is generated, the control unit 70 continuously emits ultrasonic pulses toward the eye to be examined by the probe 10 so that fluctuation information of the eye pressure to be examined due to the pulsation of the eye to be examined can be obtained. Then, arithmetic processing corresponding to each ultrasonic pulse emitted continuously is performed.

  More specifically, an ultrasonic pulse is continuously applied to the subject's eye at a predetermined time interval (eg, 0.1 second interval) within the range of the pulsation cycle of the eye to be examined (eg, within 1.5 seconds). The intraocular pressure value corresponding to each tension pulse is calculated. In this way, since a large number of intraocular pressure values can be acquired within the range of the pulsation cycle of the subject eye, changes in the intraocular pressure value of the subject eye during the pulsation cycle of the subject eye can be captured. In this case, based on each measurement value obtained within the range of the pulsation cycle of the eye to be examined, a representative value (for example, an average value of each measurement value, a central value in each measurement value), a peak of pulsation, By calculating the measurement values at the bottom and intermediate positions and outputting them to the monitor 72 or the like, it is possible to perform intraocular pressure measurement in consideration of fluctuations in the intraocular pressure value due to the pulsation of the eye to be examined.

  In the above description, the ultrasonic pulse is emitted at a predetermined time interval (for example, 0.1 second interval). However, the present invention is not limited to this, and within the range of the pulsation cycle of the eye to be examined. An ultrasonic pulse may be emitted a predetermined number of times set in advance.

  In the above configuration, the time interval or the number of times of emission when the ultrasonic pulse is continuously emitted toward the eye to be examined can be arbitrarily changed, and a setting switch for presetting the time interval or the number of times of emission is controlled. You may make it provide in the part 74. FIG.

  In the above description, the alignment detection in the Z direction is optically detected. However, the alignment detection in the Z direction may be performed by the probe 10 used for measuring the intraocular pressure. In this case, it is necessary to switch between control of the probe 10, control for measuring intraocular pressure, and control for measuring distance. Here, when distance detection with respect to the eye to be examined is performed by the probe 10, specifically, the control unit 70 emits ultrasonic waves to the eye to be examined from the vibrator 11, and then the ultrasonic waves are reflected by the eye to be examined. The working distance of the probe 10 relative to the eye to be inspected can be detected by measuring the measurement time T until the vibration detection sensor 13 detects it. In this case, if the measurement time T until the ultrasonic wave is emitted from the vibrator 11 and detected by the vibration detection sensor 13 is long, the working distance to the eye to be examined is large, and if the measurement time T is short, the working distance to the eye to be examined. Becomes shorter. In this case, the control unit 70 obtains in advance a measurement time Tk when the working distance to the eye to be examined is appropriate, and when the measurement time T measured by the probe 10 becomes Tk, alignment in the Z direction is performed. Considered complete. The distance information detected by the probe 10 is displayed on the monitor 72 as an indicator display as shown in FIG.

  In the case of the configuration as described above, for example, the controller 80 controls the probe 10 as a distance sensor for the eye to be examined before alignment is completed, and alignment in the Z direction detected by the probe 10 is performed. Is determined to be appropriate, the probe 10 is controlled as an intraocular pressure measurement sensor for the eye to be examined, and intraocular pressure measurement is performed.

  In this way, the configuration for performing alignment detection in the working distance direction with respect to the eye to be examined is performed by the probe 10 for measuring intraocular pressure, and thus the configuration can be simplified.

  In the above description, when an ultrasonic wave is incident on the eye to be examined using the probe 10, the ultrasonic wave incident on the eye to be examined is a pulse wave. However, the present invention is not limited to this, and a continuous wave is used. It may be.

  In the above description, the intraocular pressure is obtained from the difference in acoustic impedance due to the phase difference between the input phase and the output phase to the vibrator 11, but the incident wave emitted from the vibrator 11 and the vibration detection sensor 13 are used. The present invention is not limited to this as long as it compares the detected reflected wave and measures the intraocular pressure of the eye to be examined by calculation processing. For example, the intraocular pressure of the eye to be inspected may be obtained by calculation processing by comparing the frequency of the incident wave emitted from the vibrator 11 and the frequency of the reflected wave detected by the vibration detection sensor 13. More specifically, the phase difference is obtained by changing the frequency of the ultrasonic wave emitted from the vibrator 11 when a phase difference occurs between the input waveform to the vibrator 11 and the output waveform from the vibration detection sensor 13. A phase shift circuit that shifts to zero may be provided, and the intraocular pressure of the eye to be examined may be obtained by detecting the amount of frequency change when the phase difference is shifted to zero.

It is an external appearance block diagram of the non-contact-type ultrasonic tonometer concerning this embodiment. It is a figure explaining the measurement system and optical system of the non-contact-type ultrasonic tonometer concerning this embodiment. It is a figure explaining the control system of the non-contact-type ultrasonic tonometer concerning this embodiment. The anterior ocular segment observation screen displayed on the display monitor will be described. It is a figure at the time of arrange | positioning an objective lens behind a probe. It is a figure which shows the example of a change of a fixation target projection optical system and a 1st alignment parameter | index projection optical system. It is a figure which shows the structure that the probe has remove | deviated from the observation optical axis L1 regarding XY direction. It is a figure explaining the specific example of the structure by which the probe is arrange | positioned out of the observation optical path of an observation optical system. It is a schematic optical diagram which shows the specific example at the time of providing the ocular refractive power measurement optical system in the non-contact-type ultrasonic tonometer concerning this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Probe 11 Vibrator 13 Vibration detection sensor 16 Acoustic lens 18 Aperture 20 Observation optical system L1 Observation optical axis 22 Objective lens 30 Fixation target projection optical system 40 First index projection optical system 55 Working distance index projection optical system 70 Control unit 81 Amplifier 82 Frequency component analysis unit 83 Frequency phase difference specifying unit 90 Ultrasonic reflection member 310 Measurement optical system

Claims (10)

A probe having a vibrator for causing ultrasonic waves to enter the eye to be examined, and a vibration detection sensor for detecting a reflected wave from the eye to be examined;
An anterior ocular segment observation optical system in which the probe is arranged in an observation optical path for observing the anterior segment of the eye to be examined and forms an anterior ocular segment image through a peripheral region of the probe; ,
A non-contact ultrasonic tonometer characterized by comparing an incident wave emitted from the vibrator and a reflected wave detected by the vibration detection sensor and measuring an intraocular pressure of the eye to be examined by a calculation process. The non-contact ultrasonic tonometer according to claim 1,
The non-contact ultrasonic tonometer, wherein the probe is arranged on an observation optical axis of an anterior ocular segment observation optical system. The non-contact ultrasonic tonometer according to claim 2,
The non-contact ultrasonic tonometer, wherein the probe is arranged so that a central axis of the probe and an observation optical axis of an anterior ocular segment observation optical system are coaxial. The non-contact ultrasonic tonometer according to claim 2,
The anterior ocular segment observation optical system is provided with an imaging element for observing an anterior ocular segment and an objective lens for guiding an anterior ocular segment image to be examined onto the imaging element. Non-contact ultrasonic tonometer. The non-contact ultrasonic tonometer according to claim 4,
The non-contact ultrasonic tonometer, wherein the objective lens of the anterior ocular segment observation optical system is arranged behind or substantially at the same position as the probe. The non-contact ultrasonic tonometer according to claim 4,
A non-contact ultrasonic tonometer, wherein an insertion hole into which the probe is inserted is formed in an objective lens of the anterior ocular segment observation optical system. The non-contact ultrasonic tonometer according to claim 4,
The objective lens of the anterior ocular segment observation optical system is disposed in front of the probe, and an opening is formed in a portion corresponding to an ultrasonic wave propagation path by the probe. Non-contact ultrasonic tonometer. The non-contact ultrasonic tonometer according to claim 2 comprises:
A fixation target projection optical system that has a fixation light source for fixation target projection and projects a fixation target for fixing the eye to be examined toward the eye;
A non-contact super-light source characterized in that an opening for passing a fixation target projection light beam emitted from the fixation light source or the fixation light source is provided at the center of the probe. Sonic tonometer. The non-contact ultrasonic tonometer according to claim 2 comprises:
An index projection optical system having an alignment light source for projecting an alignment index and projecting the alignment index toward the anterior eye portion of the eye to be examined;
The observation optical system forms an image of the cornea reflected by the alignment light source and the anterior eye image of the eye to be examined on the two-dimensional image sensor through a peripheral region of the probe. Sonic tonometer. 10. The non-contact ultrasonic tonometer according to claim 9, wherein an opening through which an alignment light beam emitted from the alignment light source is passed is formed at the center of the probe. Contact ultrasonic tonometer.

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