JP4478672B2 - Non-contact tonometer - Google Patents

Description

  The present invention relates to a non-contact type eye for measuring intraocular pressure of a subject's eye by spraying a fluid such as air on the cornea of the subject's eye to deform the cornea and detecting and analyzing a change in index light projected onto the cornea. It relates to a pressure gauge.

  The non-contact tonometer has advantages such as non-contact and the necessity of eye anesthesia, etc., and is therefore widely used in ophthalmology and the like as a screening for glaucoma caused by high intraocular pressure. When the intraocular pressure value is greater than or equal to a predetermined value, precise examinations such as fundus examination and visual field measurement are performed.

  Further, in recent years, an apparatus that obtains a relative position between an eye to be examined and an apparatus optometry unit by detecting an index image projected on the eye to be examined, controls the stage with a motor drive, and automatically performs alignment, This is disclosed in Patent Document 1 filed by the present applicant.

  In addition, when the preset number of measurements is completed, a non-contact tonometer capable of full-automatic measurement that automatically moves to a single eye that has not yet been measured and performs positioning for practical use is also practical. It is becoming.

JP-A-9-84760

  However, in the conventional non-contact tonometer, if the eye cornea is covered with the eye cornea at the time of measurement, the cornea cannot be sufficiently deformed due to the eyelash resistance, and the original intraocular pressure value is within the normal range. Nevertheless, the measured value may become high. In addition, when the fixation of the eye to be examined is deviated, the measured value is rarely measured lower than the original intraocular pressure value. Therefore, when the intraocular pressure value is higher or lower than the predetermined value, the examiner performs remeasurement for confirmation.

  Even in such a case, in a fully automated device that detects the position of the eye to be examined and performs alignment automatically and measures the preset number of times in both eyes continuously, if one eye is measured a predetermined number of times, Then, the optometry unit is moved to the position of the other eye that has not been measured yet, and measurement is performed a predetermined number of times. Therefore, even when measurement for confirming the first eye to be examined is necessary, it is necessary to move the optometry part again, which hinders shortening of the time required for measurement. In addition, since the measurement operation of the apparatus is completed, there is a possibility that the measurement for confirmation is forgotten.

  An object of the present invention is to provide a non-contact tonometer that stops the measurement operation of the left and right eyes when the intraocular pressure value measured is higher or lower than a predetermined intraocular pressure value.

In order to achieve the above object, the non-contact tonometer according to the present invention includes an airflow spraying means for blowing an airflow to the cornea to deform the eye cornea, and measuring light is projected onto the cornea so that the cornea is caused by the airflow. In a non-contact tonometer that performs continuous measurement, a measuring means that detects corneal reflected light of the measurement light when deformed and has a predetermined radius of curvature to obtain an intraocular pressure value, Intraocular pressure value setting means for setting the lower limit value, comparison means for comparing the upper and lower limit values set by the intraocular pressure value setting means with the intraocular pressure value obtained by the measurement means, and the result of the comparison means by the and control means for controlling whether or not to stop after the end of the plurality of number of measurements continuous measurement operation was predetermined measuring means, the measuring means after the completion of a plurality of measurement times in which the predetermined based on at least one said plurality of intraocular pressure determined The control means when out of the range of the upper limit value and the lower limit value in compare unit is characterized by stopping the continuous measurement operation.

  According to the non-contact tonometer according to the present invention, a predetermined intraocular pressure value is set and compared with the obtained intraocular pressure value even when the intraocular pressure measurement is continuously performed a predetermined number of times in a series of measurement operations. If this happens, stop the continuous measurement operation. For example, by displaying that fact on the display means and notifying the operator and prompting additional measurement, it is not necessary to move the device measurement unit to the eye position again after the measurement is completed. Can do.

The present invention will be described in detail based on the embodiments shown in the drawings.
FIG. 1 shows a configuration of a measurement unit of a non-contact tonometer. An objective lens 10 and an objective lens 11 are arranged on the optical axis L1 so as to face the eye E, and a nozzle 12 is provided on the central axis thereof. It has been. Behind the nozzle 12, an air chamber 13, an observation window 14, dichroic mirrors 15 and 16, a prism diaphragm 17, an imaging lens 18, and an image sensor 19 are sequentially arranged.

  The objective lens 10 to the imaging device 19 constitute an observation system and an alignment detection system for the eye E. External eye illumination light sources 20a and 20b for illuminating the anterior segment are disposed at positions symmetrical with respect to the optical axes of the objective lenses 10 and 11, respectively.

  The dichroic mirror 16 has a characteristic of transmitting light having a wavelength emitted from the external illumination light sources 20a and 20b and reflecting a part of the light having a wavelength from an LED light source, which will be described later, also used for measurement and alignment.

  As shown in FIG. 2, the prism diaphragm 17 has three openings. The upper and lower openings are provided with prisms 17a and 17b for deflecting light beams in different left and right directions. The part is provided with a filter having spectral characteristics that absorbs the wavelength light from the external light sources 20a and 20b and transmits the wavelength light from the LED light source for both measurement and alignment.

  On the other hand, on the optical axis L2 in the reflection direction of the dichroic mirror 15, the LED light source 21 and the projection lens 22 used for both measurement and alignment are arranged, and a measurement light projection system and an alignment index projection system are configured. . Further, although not shown in the figure, a dichroic mirror having a characteristic of reflecting visible light and transmitting infrared light is obliquely installed at an angle of 45 degrees on the optical axis L2, and the reflection direction is on the optical axis. Is provided with a fixation lamp projection system that presents a fixation lamp for fixation of the eye E to the eye E.

  On the optical axis L3 in the reflection direction of the dichroic mirror 16, a lens 23, a pinhole plate 24, and a photodetector 25 are arranged. The objective lens 10, 11 to dichroic mirror 16, lens 23, pinhole plate 24, and photodetector 25 constitute a corneal deformation detection system that detects a change in the amount of corneal reflection light.

  A piston 28 that is pushed up by the drive of a solenoid 27 is slidably fitted to the cylinder 26 in the air chamber 13. The nozzle 12, the air chamber 13, the solenoid 27, and the piston 28 constitute a pressurizing unit. The air chamber 13 is provided with a pressure sensor 29 for monitoring the pressure in the air chamber 13.

  An output of the image sensor 19 is connected to a control unit 31, and an operation unit 32, a monitor 33, a solenoid 27, and an LED light source 21 are connected to the control unit 31. 1 is mounted on a stage unit (not shown) and is driven in a triaxial direction with respect to the eye E to be examined in the direction of the optical axis L1 and the direction perpendicular to the optical axis L1. It has come to be.

  When the operator presses a measurement start switch provided on the operation unit 32, the illumination light beams from the external eye illumination light sources 20a and 20b illuminate the anterior segment of the eye E to be examined. The illumination light beam reflected and scattered by the anterior eye part is made into substantially parallel light by the objective lenses 10 and 11, passes through the observation window 14 and the dichroic mirrors 15 and 16, and then passes through the opening at the center of the prism diaphragm 17. An image is formed on the image sensor 19 by the imaging lens 18.

  The control unit 31 performs binarization processing with an appropriate threshold value from the anterior segment image obtained from the image sensor 19 to detect the pupil to obtain the pupil center, and calculates the optical axis L1 of the apparatus measurement unit and the eye pupil to be examined. When the relative position in the plane in the xy direction perpendicular to the optical axis L1 is not within the allowable range, the stage is driven to move the apparatus measurement unit, and rough alignment is performed so as to be within the allowable range.

  When the alignment in the plane perpendicular to the optical axis between the eye E and the apparatus measurement unit is almost finished, the control unit 31 turns on the LED light source 21. The luminous flux from the LED light source 21 is temporarily imaged in the nozzle 12 by the projection lens 22 and the dichroic mirror 15, reaches the eye E to be examined, and is reflected by the cornea Ec. The reflected light beam at the cornea Ec is collected by the objective lenses 10 and 11, and after passing through the observation window 14, approximately 50% of the light beam passes through the dichroic mirror 15 and part of it passes through the dichroic mirror 16.

  The light beam that has passed through the dichroic mirror 16 is divided into three light beams by the three apertures of the prism diaphragm 17, and forms an image on the image sensor 19 by the imaging lens 18. At this time, the light beams that have passed through the upper and lower openings of the prism diaphragm 17 are deflected by the deflection prisms 17a and 17b in the direction toward the back and the front of the paper, respectively. The positional relationship of the corneal luminescent spot image divided into three changes depending on the relative position between the eye E to be examined and the apparatus measurement unit, and the positional relationship of the corneal luminescent spot image divided into three is detected. The positional relationship between the optometry E and the apparatus measurement unit can be known.

  For example, when the distance between the eye to be examined E and the apparatus measurement unit is longer than a predetermined distance, the corneal bright spot image at the back of the paper surface on the image sensor 19 moves downward, and the corneal bright spot image at the front of the paper surface moves upward. On the other hand, when the distance between the eye E and the apparatus measurement unit is shorter than the predetermined distance, the corneal luminescent spot image at the back of the paper on the image sensor 19 moves upward, and the corneal luminescent spot image at the front of the paper moves downward. To do. Further, when there is a deviation in the plane perpendicular to the optical axis between the eye E and the device measurement unit, by detecting the center of gravity of the three corneal luminescent spot images or the position of the central corneal luminescent spot image, It is possible to know the positional relationship between the eye E and the device measurement unit.

  The control unit 31 drives the stage and performs precise alignment so that the obtained positional relationship between the eye E to be examined and the apparatus measurement unit is within a predetermined range. When the alignment between the eye E and the apparatus measurement unit is completed by this alignment, the control unit 31 drives the solenoid 27 to move the piston 28. Then, the pressure in the air chamber 13 rises, and the pressure is detected by the pressure sensor 29. At the same time, a strong air flow accompanying the pressure rise in the air chamber 13 flows from the nozzle 12 to the cornea Ec of the eye E to be examined. Be sprayed. The cornea Ec gradually begins to deform according to the strength of the airflow.

  In the corneal deformation detection system, the luminous flux emitted from the LED light source 21 and projected onto the cornea Ec is reflected by the cornea Ec when the radius of curvature R of the cornea becomes a predetermined curvature radius Ra by the airflow generated in a pulse shape. The pinhole plate 24 is disposed at a position optically conjugate with the virtual image formed by the objective lens 10, 11, and the lens 23, and only the light beam that has passed through the pinhole of the pinhole plate 24 is provided. Detection is performed by the photodetector 25. In the non-contact tonometer of this embodiment, as the radius of curvature R of the cornea Ec approaches the predetermined radius of curvature Ra, the amount of light received by the photodetector 25 increases, and reaches a peak value when the radius of curvature Ra is infinite, that is, the cornea Ec. The peak value is detected when the plane becomes flat due to the compressed air emitted in a pulse shape.

  Therefore, it is necessary to transform the radius of curvature of the cornea Ec into Ra by obtaining the value of the output signal of the pressure sensor 29 when the output signal of the photodetector 25 of the corneal deformation detection system takes the peak value. The pressure is obtained, and the intraocular pressure value P of the eye E can be converted from this value.

  FIG. 3 is a flowchart of the control operation of this embodiment. In step S1, the rough alignment based on the pupil position detection, the precise alignment based on the corneal bright spot detection, the drive of the solenoid 27, and the intraocular pressure measurement based on the detection of the corneal deformation are performed.

  Next, the operation of the control unit 31 determines whether or not n intraocular pressure measurements preset in step S2 have been completed. If there are n measured intraocular pressure values P1, P2,..., Pn, the process proceeds to step S3. If the number is less than n, the process returns to step S1, and alignment and intraocular pressure measurement are performed again.

  Here, FIG. 4 shows a setting screen displayed on the monitor 33. In the embodiment, as shown in FIG. 4, two values can be set in advance in the control unit 31. “UPPER LIMIT: 20 mmHg ON” shown in FIG. 4 means an upper limit PH that changes a series of measurement operations when the measured intraocular pressure P exceeds 20 mmHg. “UNDER LIMIT: 6 mmHg OFF” means a lower limit PL for changing a series of measurement operations when the measured intraocular pressure value P is less than 6 mmHg, but here it is “OFF”. Therefore, this lower limit value is set invalid.

  Note that the set values of the upper limit PH and the lower limit PL can be changed to arbitrary values, and whether to enable or disable them can be set arbitrarily.

  In step S3, the control unit 31 compares each of the N intraocular pressure values P1, P2,..., PN measured N times with the upper limit PH, and at least one intraocular pressure P exceeding the upper limit PH. Determine if there is. If there is no intraocular pressure value P exceeding the upper limit PH, the process proceeds to step S4. In the embodiment, since the lower limit value PL is set to invalid, the process passes through step S4 and proceeds to step S5.

  In step S5, it is determined whether the intraocular pressure measurement for the left and right eyes is complete. When the intraocular pressure measurement for the left and right eyes has been completed, the control unit 31 completes the measurement operation. When the intraocular pressure measurement for the left and right eyes has not ended, the operation of the control unit 31 proceeds to step S6, drives the stage, and moves the apparatus measurement unit toward the other eye that has not ended the intraocular pressure measurement. .

  When the left-right movement is completed, the operation by the control unit 31 proceeds to step S1, and for the eye to be examined that has not yet been measured, rough alignment by pupil position detection, precision alignment by corneal bright spot detection, driving of the solenoid 27, corneal deformation Measure intraocular pressure by detection. Thereafter, the process proceeds in the order of steps S2 to S5 described above, and when the intraocular pressure measurement for the left and right eyes is completed, the measurement operation is completed.

  On the other hand, in step S3, each of the N intraocular pressure values P1, P2,..., PN measured N times is compared with the upper limit PH, and there is an intraocular pressure value P that exceeds the upper limit PH. Then, the operation by the control unit 31 proceeds to step S7.

  Here, FIG. 5 is an explanatory diagram of the screen of the monitor 33 when the intraocular pressure value and the message M when the predetermined number of measurements N = 2 are displayed. When it is determined in step S3 that at least one intraocular pressure value Pn exceeds the upper limit PH, the control unit 31 displays N intraocular pressure values P1, P2,. A message M is displayed to inform the operator that there is an intraocular pressure value P exceeding the upper limit PH and to prompt additional measurement for confirmation, and the continuous measurement operation is stopped. And it will be in the state of waiting for input to each operation switch etc. of the operation part 32. FIG.

  When the operator determines that an additional tonometry is required in this input waiting state and presses the measurement start switch of the operation unit 32, the operation of the control unit 31 proceeds to step S9. In step S9, the same control as the above-described step S1 is performed, and rough alignment based on pupil position detection, precise alignment based on corneal bright spot detection, solenoid 27 driving, and intraocular pressure measurement based on corneal deformation detection are performed.

  When the additional intraocular pressure measurement is completed, the state again waits for input to each operation switch of the operation unit 32. Further, when the operator waits for the input and determines that no further tonometry is required and presses the R / L movement switch of the operation unit 32, the operation of the control unit 31 proceeds to step S10. .

  In step S10, the stage is driven, the apparatus measurement unit is moved in the left-right direction to the position of the other eye, and an input waiting state for each operation switch of the operation unit 32 is awaited. Here, when the operator presses the measurement start switch of the operation unit 32, the operation of the control unit 31 proceeds to step S1, and the above-described series of measurement operations of steps S1 to S5 are performed.

  As described above, the non-contact tonometer that performs the intraocular pressure measurement for a predetermined number of times in the left and right eyes continuously in a series of measurement operations sets the upper limit value PH and the lower limit value PL, and calculates the obtained intraocular pressure value P. When the obtained intraocular pressure value P is larger than the upper limit value PH or the intraocular pressure value P is smaller than the lower limit value PL, a series of continuous measurement operations are performed. To stop. Then, it is necessary to move the apparatus measurement unit to the eye position again after the left and right eye measurements are completed by displaying the fact on the display means such as the monitor 33 and notifying the operator to prompt additional measurement. Since it is not, additional measurement can be performed efficiently. It is also possible to prevent the operator from forgetting the additional measurement for confirmation.

  In the above-described embodiment, when it is determined that the obtained intraocular pressure value P is abnormal, the fact is displayed on the display means such as the monitor 33 and notified to the operator. The same effect can be obtained.

It is a block diagram of an Example. It is a perspective view of a prism diaphragm. It is a flowchart figure of control operation. It is explanatory drawing of the setting screen of a monitor. It is explanatory drawing of the intraocular pressure value and message on a monitor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 11 Objective lens 12 Nozzle 13 Air chamber 15, 16 Dichroic mirror 17 Prism diaphragm 19 Imaging device 20 LED light source 20a, 20b External eye light source 25 Photo detector 27 Solenoid 28 Piston 29 Pressure sensor 31 Control unit 32 Operation unit 33 Monitor

Claims (4)

Airflow spraying means for blowing an airflow to the cornea to deform the eye cornea to be examined, and corneal reflection light of the measurement light when the measurement light is projected onto the cornea and the cornea is deformed by the airflow and has a predetermined radius of curvature. In a non-contact tonometer that performs continuous measurement, an intraocular pressure value setting unit that sets an upper limit value and a lower limit value of the intraocular pressure value, and the intraocular pressure value setting A comparison means for comparing the upper limit value and the lower limit value set by the means with the intraocular pressure value obtained by the measurement means, and a continuous measurement operation of the measurement means based on a result of the comparison means for a plurality of predetermined measurement times. Control means for controlling whether to stop after completion , and at least one of a plurality of intraocular pressure values obtained by the measurement means after completion of the plurality of predetermined measurement times is the upper limit value in the comparison means. And out of the range of the lower limit Non-contact type tonometer said control means, characterized in that stopping the continuous measurement operation.   The non-contact tonometer according to claim 1, wherein the intraocular pressure value setting means can change the upper limit value and the lower limit value to be set to arbitrary values. Non-contact type tonometer according to claim 1 or 2, wherein the control unit and notifying the operator the results of the comparison means.   The non-contact tonometer according to claim 3, wherein the control means notifies the operator by displaying the result of the comparison means on a display means.

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