JP5443225B2 - Non-contact tonometer - Google Patents

Description

  In the present invention, the cornea is deformed (applanation) by blowing an airflow from an airflow blowing nozzle toward the cornea of an eye to be examined, and a reflected light beam from the cornea in the applanation state is received to measure intraocular pressure. The present invention relates to a contact tonometer.

  Conventionally, the cornea is deformed (applanation) by blowing an airflow from an airflow blowing nozzle toward the cornea of the eye to be examined, and the reflected light beam from the cornea at this time is received, and the intraocular pressure is determined based on the detection of the corneal deformation. A non-contact tonometer for measuring is known (for example, see Patent Document 1).

  In addition to the airflow nozzle, this non-contact tonometer is an anterior ocular segment observation optical system for observing the anterior eye image of the subject eye, and the fixation target of the subject toward the subject eye through the airflow nozzle. A fixation optical system that emits visible light, an alignment projection optical system that projects an alignment light beam toward the eye to be examined, an alignment light receiving optical system that receives an alignment reflected light beam reflected by the cornea of the eye to be examined, and an intraocular pressure measurement For this purpose, a detection optical system for detecting corneal deformation of the eye to be examined is provided.

  At the time of measuring intraocular pressure, while the subject is looking at the fixation target from the inside of the nozzle, the airflow is ejected from the airflow spray nozzle, the change in the reflected light beam from the cornea is detected by the detection optical system, and the intraocular pressure is detected. The measurement is performed.

JP-A-8-280631

  However, in the conventional non-contact tonometer, since the measurement is performed while the fixation target is seen through the inside of the airflow spray nozzle from the front of the subject, when the subject's eyelashes cover the cornea, In some cases, an appropriate applanation of the cornea was not achieved by obstructing the flow of the airflow blown from the airflow spray nozzle.

  The present invention has been made paying attention to the conventional problems as described above, and provides a non-contact tonometer capable of suppressing the flow of air blown from the airflow spray nozzle to the cornea. It is an object.

  In order to achieve the above object, the non-contact tonometer of the present invention is provided coaxially with the optical axis of the anterior ocular segment observation optical system, is separated from and is close to the eye to be examined, and is on the cornea of the eye to be examined. An intraocular pressure value based on airflow spray nozzles for blowing airflow, fixation target presenting means for presenting a fixation target to the eye to be examined, and detection information accompanying deformation of the cornea when the airflow is blown to the eye to be examined And a relative position between the airflow spray nozzle and the fixation target presenting means is configured such that the airflow is viewed from below with respect to a visual axis when the eye to be inspected fixes the fixation target. It is set to spray.

  The invention described in claim 2 is the non-contact tonometer according to claim 1, in which the fixation target presenting means is arranged such that the airflow spray nozzle is disposed in front of the eye to be examined. It is provided at a position above the airflow spray nozzle so as to turn the eye to be examined upward when the fixation target is fixed.

  According to a third aspect of the present invention, in the non-contact tonometer according to the first or second aspect, a central fixation target is placed on the eye to be examined from the direction of the optical axis through the air blowing nozzle. A central fixation target presenting means for presenting is provided.

  According to a fourth aspect of the present invention, in the non-contact tonometer according to the third aspect of the present invention, the non-contact tonometer includes a switching unit that switches a presentation state of the upper fixation target and the central fixation target. To do.

  The invention according to claim 5 is the non-contact tonometer according to claim 3 or claim 4, wherein the calculation means calculates the intraocular pressure value obtained when the upper fixation target is presented. A conversion means for converting into an intraocular pressure value obtained when the central fixation target is presented is provided.

In the non-contact tonometer according to the first aspect of the present invention, at the time of measuring the intraocular pressure, the subject has fixed the fixation target presented by the fixation index presenting means, and the air blowing nozzle from below the fixation direction. Spray an air stream.
As described above, since the airflow is blown from below the fixation direction of the eye to be inspected, the airflow blowing by upper eyelids or eyelashes is less likely to occur compared to the case where the airflow is blown from the same direction as the fixation direction.

  Furthermore, the non-contact tonometer according to claim 2 is configured such that when the airflow spray nozzle is disposed in front of the eye to be examined and the subject fixes the fixation target above, the eye to be examined is turned upward. Accordingly, the upper eyelashes and eyelashes are lifted upward. Therefore, the upper eyelids and eyelashes are less likely to inhibit the airflow from the airflow spray nozzles by the amount that the upper eyelashes and eyelashes are lifted upward.

  Further, in the inventions according to claims 3 and 4, since the fixation target and the central fixation target can be selected at the time of measuring the intraocular pressure, either one is selected according to the state of the upper eyelid or eyelash of the subject. Is preferable.

  In the invention according to claim 5, even when a measurement target is measured by presenting a fixation target above the airflow spray nozzle, a more accurate intraocular pressure measurement value can be obtained.

1A and 1B are diagrams showing a non-contact tonometer according to Embodiment 1, wherein FIG. 1A is a rear view of the non-contact tonometer, and FIG. 1B is a side view of the non-contact tonometer. FIG. 2 is a side view of the optical system of the non-contact tonometer. FIG. 3 is an explanatory view showing reflection of XYZ alignment index light projected from the front direction onto the cornea of the eye to be examined by a non-contact tonometer. FIG. 4 is an explanatory diagram of the eye to be examined when the central fixation target is fixed, (a) is a diagram showing an anterior segment image displayed on the monitor screen, and (b) is the central fixation target. It is the figure which looked at the eye to be examined when I fixed it. FIG. 5 is a sectional view showing the central fixation target optical system and the upper fixation target optical system of the non-contact tonometer. FIG. 6 is an explanatory diagram of the eye to be examined when the upper fixation target is fixed, (a) is a diagram showing an anterior segment image displayed on the monitor screen, and (b) is the upper fixation target. It is the figure which looked at the eye to be examined when I fixed it. FIG. 7 is a diagram for explaining the difference in thickness between the apex and its periphery in the cornea. FIG. 8 is a side arrangement diagram of the optical system of the non-contact tonometer of the second embodiment. FIG. 9 is a side view of the optical system of the non-contact tonometer of the third embodiment.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to the accompanying drawings.

(Embodiment 1)
In FIG. 1, S is a non-contact tonometer.
The non-contact tonometer S includes a device base 2, a gantry 3, and a device body 4.
The apparatus base 2 has a cradle 1 that supports the face HB of the subject.

  The gantry 3 is provided to be movable in the front-rear direction and the left-right direction with respect to the apparatus base 2. In addition, the arrow Z shows the front-back direction, the arrow X shows the left-right direction, and the arrow Y shows the up-down direction.

  The apparatus main body 4 is provided in the upper part of the gantry 3 and is moved in the front-rear direction, the left-right direction, and the up-down direction with respect to the gantry 3 by the operation of internal driving means and driving mechanism.

  The gantry 3 is provided with an operation knob 5 having an operation button 5a, a monitor 6, and the like. The operation knob 5 is operated by the examiner, whereby the gantry 3 is moved back and forth and left and right. Further, an airflow blowing nozzle 8 is provided on the front surface of the apparatus body 4 through the anterior eye glass 13 (see FIG. 2) so as to face the subject's eye E of the subject.

  The apparatus main body 4 includes an anterior ocular segment observation optical system 10, an XYZ alignment index projection optical system 20, a central fixation target optical system (central fixation target presenting means) 30, and an XYZ alignment detection optical system shown in FIG. 40, a corneal deformation detection optical system 50, an upper fixation target optical system (fixation target presenting means) 60, and a control circuit 80 are provided.

  The anterior ocular segment observation optical system 10 is for observing the anterior ocular segment of the eye E to be examined. The anterior ocular segment illumination light source (not shown), the anterior ocular window glass 12, the chamber window glasses 13 and 14, and the half. The mirror 15, the objective lens 16, the half mirrors 17 and 18, the CCD camera 19, and the like, and O 1 is the optical axis.

  The anterior segment image of the eye E is transmitted through the anterior segment window glass 12, the chamber window glasses 13 and 14, and the half mirror 15, and is focused by the objective lens 16 and transmitted through the half mirrors 17 and 18. Formed on top.

  The XYZ alignment index projection optical system 20 projects index light for XYZ direction alignment detection and corneal deformation detection onto the cornea C of the eye E from the front.

  The central fixation target optical system 30 provides a central fixation target to the eye E to be inspected substantially coaxially with the optical axis O1 through the inside of the airflow spray nozzle 8, and a central fixation target light source 31 that emits visible light. , Pinhole plate 32, dichroic mirror 25, projection lens 26, half mirror 15, chamber window glass 14, and the like.

  The fixation target light emitted from the central fixation target light source 31 is converted into parallel light by the projection lens 26 via the pinhole plate 32 and the dichroic mirror 25, reflected by the half mirror 15, and then the airflow spray nozzle 8. And is guided to the eye E to be examined. The subject fixes the central fixation target.

  The XYZ alignment index projection optical system 20 is configured to make the focal point coincide with the light source 21 for XYZ alignment that emits infrared light, the condenser lens 22, the aperture stop 23, the pinhole plate 24, the dichroic mirror 25, and the pinhole plate 24. It comprises a projection lens 26, a half mirror 15, a chamber window glass 14 and the like disposed on the optical path.

  The infrared light emitted from the XYZ alignment light source 21 is guided to the pinhole plate 24, and the light beam that has passed through the pinhole plate 24 is reflected by the dichroic mirror 25 and converted into a parallel light beam by the projection lens 26. After being reflected at 15, it passes through the inside of the airflow spray nozzle 8 to form the XYZ alignment index light K shown in FIG. FIG. 3 shows a state in which the central fixation target is presented by the central fixation target optical system 30, and the XYZ alignment index light K is the curvature of the intersection XO between the optical axis O1 and the cornea C and the cornea C. Reflected by the corneal surface T so as to form a bright spot image R at an intermediate position from the center.

  The XYZ alignment detection optical system 40 receives the reflected light beam of the XYZ alignment index light K from the cornea C and detects the positional relationship between the non-contact tonometer S and the cornea C in the XYZ directions.

  The XYZ alignment detection optical system 40 includes a chamber window glass 14, a half mirror 15, an objective lens 16, half mirrors 17 and 18, a sensor 41, an XYZ alignment detection circuit 42, and the like.

The reflected light beam of the XYZ alignment index light K reflected by the cornea C is reflected by the half mirror 18 to form a bright spot image R′1 on the sensor 41. This sensor 41 is a light receiving sensor capable of detecting a position such as a PSD.
The XYZ alignment detection circuit 42 calculates the positional relationship (XYZ direction) between the non-contact tonometer S and the cornea C based on the output of the sensor 41 by a known means, and outputs the calculation result to the control circuit 80. To do.

  On the other hand, the light flux reflected by the cornea C transmitted through the half mirror 18 forms a bright spot image R ′ 2 on the CCD camera 19. The CCD camera 19 outputs an image signal to the monitor 6 through the control circuit 80, and as shown in FIG. 4A, the anterior segment image E ′ of the eye E and the bright spot image of the XYZ alignment index light K R′2 is displayed on the screen G of the monitor 6. In FIG. 4A, KO indicates the glow of the eye E, and D indicates the pupil.

  Returning to FIG. 2, the corneal deformation detection optical system 50 detects the amount of deformation of the cornea C by receiving the reflected light beam of the XYZ alignment index light K from the cornea C. The XYZ alignment index projection optical system 20 applies the corneal deformation detection optical system 50 to the cornea C. A part of the reflected light beam projected and reflected by the corneal surface T is reflected by the half mirror 17, guided to the corneal deformation detection optical system 50, passed through the pinhole plate 51, and guided to the sensor 52.

  The upper fixation target optical system 60 is disposed above the airflow blowing nozzle 8 in the apparatus main body 4 to provide the upper fixation target to the eye E, and emits visible light as shown in FIG. An upper fixation target light source 61 and a cover 63 that covers the upper fixation target light source 61 and has an emission port 62 that emits visible light of the upper fixation target light source 61 toward the eye E to be examined. I have. The subject turns his / her eye E upward by fixing the light source 61 for the upper fixation target as the upper fixation target. In FIG. 5, O3 indicates the line of sight of the eye E at this time, and the line of sight O3 is directed approximately 30 degrees upward with respect to the optical axis O1.

Returning to FIG. 2, the changeover switch 91 switches the lighting of the upper fixation target light source 61 of the upper fixation target optical system 60 and the central fixation target light source 31 of the central fixation target optical system 30. .
Based on the detection of the XYZ alignment detection circuit 42, the control circuit 80 drives the motor (not shown) that drives the apparatus main body 4 to execute alignment, and the alignment adjustment between the apparatus main body 4 and the eye E is completed. Then, control is performed to blow airflow from the airflow blowing nozzle 8 toward the cornea C of the eye E to be examined.

Based on the corneal deformation amount detected by the corneal deformation detection optical system 50, the arithmetic circuit 81 provides an intraocular pressure value Ha measured by presenting the central fixation target and an intraocular pressure measured by presenting the upper fixation target. It has a function of calculating the value Hb.
The conversion circuit 82 has a function of converting the intraocular pressure value Hb obtained in the presentation state of the upper fixation target into an intraocular pressure value Ha ′ corresponding to the intraocular pressure value Ha obtained in the central fixation target presentation state. Details thereof will be described later.

(Operation of Embodiment 1)
At the time of measuring the intraocular pressure, the examiner operates the changeover switch 91 to present one of the upper fixation target and the central fixation target and perform measurement.

  When the upper fixation target is presented and the subject fixes it, as shown in FIG. 5, the eye E is turned upward and the line of sight O3 is directed upward. FIG. 6A shows the screen G of the monitor 6 at this time. The position of the glow KO of the anterior segment image E ′ is higher than the position of the optical axis O1, and the upper eyelid 72 and eyelashes. 71 moves upward. FIG. 6B shows a state where the eye E is viewed from the side when the upper fixation target is fixed. The upper eyelid 72 and the eyelashes 71 are more than the front of the airflow spray nozzle 8. Move upward.

  When the alignment adjustment is completed, an airflow is blown from the airflow blowing nozzle 8 to the eye E. In the presentation state of the upper fixation target, as shown in FIG. 6, the airflow is blown onto the area AR including the optical axis O1 shifted downward from the apex P of the cornea C.

  Therefore, in the presentation state of the upper fixation target, as shown in FIG. 6B, the upper eyelid 72 and the eyelashes 71 are prevented from moving upward and obstructing the flow of the airflow A blown from the airflow blowing nozzle 8. Intraocular pressure can be measured by performing appropriate corneal applanation. In addition, at this time, since the measurement can be performed with the eyes away from the airflow spray nozzle 8, the feeling of pressure and fear due to the approach of the airflow spray nozzle 8 to the subject is reduced.

On the other hand, in a state in which the eye E fixes the central fixation target, the airflow is blown onto the area AR including the optical axis O1 that coincides with the apex P of the cornea C as shown in FIG.
At this time, as shown in FIG. 4A, when the upper eyelid 72 and the eyelashes 71 do not cover the area AR to which the airflow is blown, an appropriate applanation is obtained at the time of the airflow blowing.

  On the other hand, as shown in FIG. 4B, when the eyelashes 71 cover the area AR where the airflow in the vicinity of the optical axis O1 is blown, the airflow A is obstructed by the eyelashes 71 and an appropriate corneal applanation is achieved. May not be obtained. Further, when the airflow blowing nozzle 8 approaches the eye E with the central fixation target fixed, there is a risk of giving the subject a feeling of pressure or fear. As described above, when there is a possibility that the airflow is inhibited by the eyelashes 71 in the state of the central fixation target, or there is a possibility of giving the subject a feeling of pressure or fear, the upper fixation target is used as described above. It is preferable to perform the measurement by presenting it.

Next, conversion by the conversion circuit 82 will be described.
As shown in FIG. 7, the thickness of the cornea C is such that the thickness t2 in the vicinity of the intersection XO with the optical axis O1, which is a portion where the air current is blown in a state where the upper fixation target is fixed, is the central fixation target. It is thicker than the thickness t1 of the cornea C in the vicinity of the apex P where the airflow is blown in a fixed state (for example, t1 = about 500 μm, whereas t2 = 500 + 50 μm).

  Accordingly, as shown in FIG. 7, the corneal deformation when the air flow is blown near the intersection XO with the optical axis O1 in the state where the upper fixation target is fixed and the eye E is turned upward is the central fixation. This is different from the corneal deformation when the target is fixed and airflow is blown near the apex P of the cornea C. Therefore, the intraocular pressure value Hb obtained in the fixation state of the upper fixation target is the fixation of the central fixation target. It is different from the intraocular pressure value Ha obtained in the state.

Therefore, in the first embodiment, when the conversion circuit 82 corrects the intraocular pressure value Hb calculated by the arithmetic circuit 81 in a state where the upper fixation target is presented, the central fixation target is fixed. Is converted into an intraocular pressure value Ha ′ corresponding to the intraocular pressure value Ha that would be obtained in the above.
In this case, the intraocular pressure value Hb calculated by presenting the upper fixation target may be multiplied by a preset coefficient to obtain a converted value (intraocular pressure value Ha ′), or the eye pressure value may be determined in advance. A conversion value (intraocular pressure value Ha ′) for the pressure value Hb may be stored in the form of a table. Further, the thickness t2 of the cornea C at the position of the optical axis O1 when the upper fixation target is fixed may be measured, and a converted value (intraocular pressure value Ha ′) may be obtained according to this measured value. .
As a means for measuring the thickness of the cornea C, as described in Japanese Patent Application Laid-Open No. 11-276440 filed by the applicant of the present application, the optical axis O1 and Z alignment detection of the anterior ocular segment observation optical system 10 are detected. The calculation can be performed by giving the optical axis angle θ formed by the optical axis of the optical system, the image magnification at the position of the sensor 52 and the surface curvature of the cornea C.

(Effect of Embodiment 1)
a) When the measurement is performed by presenting the central fixation target, the eyelash 71 of the subject is likely to inhibit the flow of the airflow of the airflow spray nozzle 8, or the eyelash 71 inhibits the flow of the airflow and the intraocular pressure. When the value Ha cannot be obtained, the examiner can measure the intraocular pressure value Hb by presenting the upper fixation target and blowing the airflow in a state in which the subject has fixed the upper fixation target. .
In the fixation state of the upper fixation target, as shown in FIG. 6B, the upper eyelid 72 and the eyelashes 71 move upward, and the eyelashes 71 are less likely to block the air flow, so that the occurrence of measurement errors can be suppressed. .
The eyelashes 71 that obstruct the airflow are caused not only by individual differences but also by race differences. For example, the Oriental has a lower eyelash 71 when the airflow is blown compared to the Westerners. Tend to get in the way. In particular, when measuring an intraocular pressure value such that the eyelashes 71 block the airflow, it is preferable to switch the changeover switch 91 to the side that presents the upper fixation target in advance so that measurement errors can be avoided. .

  b) When performing measurement by presenting the central fixation target, if the subject feels pressure or fear to the airflow spray nozzle 8, the upper fixation target is presented and the subject's line of sight is airflow The intraocular pressure value Hb can be measured in a state where the feeling of pressure and fear are suppressed by removing the spray nozzle 8 upward.

  c) When the intraocular pressure measurement is performed in the state in which the upper fixation target is presented, the conversion circuit 82 converts the measured intraocular pressure value Hb into the intraocular pressure value Ha that would be obtained when the central fixation target is presented. Since conversion is performed, an intraocular pressure value Ha ′ corresponding to the intraocular pressure value Ha when the central fixation target is presented can be obtained as usual.

(Other embodiments)
Hereinafter, a non-contact tonometer according to another embodiment will be described.
In describing other embodiments, the same components as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted. Regarding the action, the action different from that of the first embodiment will be described, and the description of the same action as that of the first embodiment will be omitted.

(Embodiment 2)
Next, the non-contact tonometer S of Embodiment 2 will be described. The second embodiment is an example in which the presentation of the upper fixation target and the presentation of the central fixation target are also performed automatically.

In the non-contact tonometer S of the second embodiment, a switching circuit 83 is provided as shown in FIG.
The switching circuit 83 switches between turning on and off the light source 31 for the central fixation target and the light source 61 for the upper fixation target. Switching of presentation of both fixation targets by the switching circuit 83 is performed by operating the switch 91. In addition to the measurement error.
That is, the switching circuit 83 normally presents the central fixation target by the central fixation target optical system 30 when measuring the intraocular pressure, but the presentation of the upper fixation target is selected by manual operation of the changeover switch 91. If the measurement error occurs in the presentation state of the central fixation index, the presentation of the central fixation target is stopped and the upper fixation target is presented.

(Embodiment 3)
FIG. 9 is a side view of the optical system of the non-contact tonometer according to the third embodiment. In the non-contact tonometer of the third embodiment, the fixation target presenting means is arranged in the front direction of the eye E, and the airflow spray nozzle 8 is installed obliquely upward at a position below the fixation target presenting means. It is an example. The light of the non-contact tonometer of the third embodiment includes a corneal thickness measuring unit 300 that measures the corneal thickness, and the slit light projection system 320 that projects the slit light in the corneal thickness measuring unit 300 is fixed. It also serves as a sign presentation means.

Hereinafter, it demonstrates in detail based on FIG.
The apparatus main body 4 is provided with a corneal thickness measuring means 300, and the corneal thickness measuring means 300 includes a slit light projection system 320 and a slit light receiving system 330.
The slit light projection system 320 includes a light source 321, a slit plate 322, and a projection lens 323, and the optical axis O <b> 31 is installed substantially horizontally so that it can be placed in the front direction of the eye E during tonometry. . Further, the slit plate 322 has a slit on the cornea C that forms slit light extending in the horizontal direction (in the drawing, the direction orthogonal to the paper surface). The slit plate 322 and the projection lens 323 are arranged based on the Scheinproof principle with respect to the slit image formed in the cornea C. In other words, the slit surface of the slit plate 322, the main plane of the projection lens 323, and the extended surface of the image plane of the slit are arranged so as to intersect at one intersection line.

The slit light receiving system 330 includes an imaging lens 331 and a CCD camera 332, and the optical axis O32 is installed at an angle θ3 with respect to the optical axis O31 of the slit light projection system 320. The imaging lens 331 and the CCD camera 332 are shined such that the light cross section (O31) by the slit light beam, the main plane of the imaging lens 331, and the imaging surface of the CCD camera 332 intersect at a single intersection line. The arrangement is based on the proof principle.
An anterior ocular segment observation optical system 310 is attached to the apparatus main body 4 with the optical axis O1 inclined obliquely upward between the slit light projection system 320 and the slit light receiving system 330. And the airflow spray nozzle 8 is installed in the apparatus main body 4 so that the front-end | tip turns diagonally upwards coaxially with the optical axis O1. The anterior ocular segment observation optical system 310 is provided with half mirrors 314, 315, 316, an objective lens 317, an imaging lens 318, and a CCD camera 319. The half mirrors 314, 315, 316 are the same as in the embodiment. As in FIG. 1, the XYZ alignment index projection optical system 20, the XYZ alignment detection optical system 40, and the corneal deformation detection optical system 50 are omitted.

Next, the operation of the non-contact type tonometer of Embodiment 3 will be described.
In the third embodiment, slit light is projected by the slit light projection system 320 after the alignment is completed. Then, the subject is made to fix the front slit light as an upper fixation target, and the intraocular pressure measurement is performed in a state where the apex P of the cornea C is overlapped with the optical axis O31. At this time, the airflow blowing nozzle 8 blows an airflow from the lower side of the fixation direction of the eye E to the area AR shifted downward with respect to the apex P of the cornea C.

  Therefore, the airflow blown from the airflow blowing nozzle 8 is not easily affected by the eyelashes 71 as in the first and second embodiments, and the airflow is blown from a direction different from the fixation direction of the subject. Is hard to feel fear.

  In the third embodiment, a corneal cross-sectional image of the slit light flux is captured by the CCD camera 332 of the slit light receiving system 330, and the thickness (t1) of the cornea is measured based on the corneal cross-sectional image. The conversion circuit 82 measures the thickness (t1) in the vicinity of the apex P of the cornea C, which is the position of the optical axis O31, and the intraocular pressure value calculated by the arithmetic circuit 81 based on the thickness (t1). Correction to Hb is performed and converted into an intraocular pressure value Ha ′ corresponding to the intraocular pressure value Ha that would be obtained at the apex P.

  Thus, since the conversion circuit 82 detects the thickness of the cornea C and corrects the intraocular pressure value Hb, the conversion circuit 82 performs detection with higher accuracy than that in which the thickness of the cornea C is not detected. be able to.

  The embodiments of the present invention have been described with reference to the drawings. However, the present invention is not limited to these embodiments, and various modifications and substitutions may be made without departing from the scope of the present invention. Can do.

  For example, in the first embodiment, the one provided with the central fixation target optical system 30 as the central fixation target presenting means is shown. However, only the upper fixation target presenting means may be provided.

  In the first embodiment, the direction of the line of sight O3 when the upper fixation target is presented toward the eye E is set to be 30 ° upward with respect to the optical axis O1, but this angle is 30 °. It is not limited.

8 Airflow spray nozzle 60 Upper fixation target optical system (fixation target presenting means)
81 arithmetic circuit C cornea E eye to be examined O1 optical axis (of the anterior ocular segment observation optical system)

Claims (5)

An airflow spray nozzle that is provided coaxially with the optical axis of the anterior ocular segment observation optical system, is separated from or approaches the eye to be examined, and airflow is blown to the cornea of the eye to be examined.
Fixation target presenting means for presenting a fixation target to the eye to be examined;
Calculating means for calculating an intraocular pressure value based on detection information accompanying deformation of the cornea when the airflow is blown to the eye to be examined;
The relative position between the airflow spray nozzle and the fixation target presenting means is set so as to blow the airflow from below with respect to the visual axis when the eye to be examined fixes the fixation target. A non-contact tonometer.   The fixation target presenting means is configured to cause the subject's eye to turn upward when causing the subject to fixate the fixation target in a state where the air current blowing nozzle is arranged in front of the subject's eye. The non-contact tonometer according to claim 1, wherein the tonometer is provided at a position higher than the tonometer.   The central fixation target presenting means for presenting the central fixation target to the eye to be examined from the direction of the optical axis through the inside of the airflow blowing nozzle in addition to the fixation index presenting means. The non-contact tonometer according to claim 1 or 2.   The non-contact tonometer according to claim 3, further comprising switching means for switching a presentation state of the fixation target and the central fixation target.   The calculation means includes a conversion means for converting an intraocular pressure value obtained when the fixation target is presented into an intraocular pressure value obtained when the central fixation target is presented. The non-contact type tonometer according to claim 3 or 4, wherein:

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