JPH0385136A - Non-contact type tonometer - Google Patents

Abstract

PURPOSE:To enable a condition to be recognized certainly by displaying which range is in use and whether the range is suitable or not. CONSTITUTION:When a piston 2 is actuated by a solenoid 1 and air in a compression chamber 3 is compressed and ejected to a cornea Ec through a nozzle 4 so as to applanate the cornea Ec, a quantity of incident light into a photosensor 17 becomes maximum. Therefore, pressure in the compression chamber 3 is detected directly by a pressure sensor 5 and an ocular tension is measured by using a conversion formula. A change over of measurement range is carried out by switching source resistances RL and RH, which are contained in a solenoid control circuit 24 for controlling a current conducting through the solenoid 1, from one to the other with an analog switch 23. Indications concerning a selection of range and an impossibility of measurement due to over-range are made by a display element 25. A green light emitting diode(LED) is made to blink at a different frequency in case of the over-range or ill-alignment, and a red LED is made to blink in case that the measurement is impossible under a condition that RL is set as the source resistance. In case of the over-range, it is indicated by characters.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention is a non-contact method that sprays compressed fluid onto the eye to be examined to deform the cornea, detects a predetermined state of deformation, and measures the intraocular pressure of the eye to be examined. Regarding type tonometer.

[Prior Art] Conventionally, this type of non-contact tonometer generally uses compressed air as the compressed fluid. Then, the air in the compression chamber is gradually compressed by a piston operated by a solenoid, and this compressed air is injected into the cornea of the eye to be examined through a nozzle. Measure the pressure inside the compression chamber when
After that, the power to the solenoid is turned off.

In the majority of normal eyes to be examined, the intraocular pressure is approximately 30 mmH'g at most. However, a device equipped with multiple pressurization ranges so as to be able to measure even severely elevated intraocular pressure was developed in 1983-
It is known from Publication No. 300740.

[Problems to be Solved by the Invention] However, in the above-mentioned conventional example, the pressurized range is simply switched in various cases, so for example, the pressurized range is misidentified and the low range is changed to the high range instead of the high range. There is a problem in that it causes discomfort to the eye being examined.

An object of the present invention is to provide a non-contact tonometer that solves the above-mentioned problems.

[Means for Solving the Problems] According to the present invention, as exemplified in the following embodiments, the fluid ejecting means has a first range as a pressurizing range for measuring intraocular pressure, and a fluid ejecting means for the first range. A second range including a high pressure degree can be selected, and it is possible to detect that measurement is impossible because the cornea of the eye to be examined does not undergo a predetermined deformation, or to detect that the eye to be examined has been replaced, or The magnitude of the measured value is detected and the range is switched, and this is displayed on the display means.

[Embodiment] FIG. 1 shows an embodiment of the present invention, in which a piston 2 driven by a solenoid IC enters a compression chamber 3 to compress air in the compression chamber 3, and the compressed air is passed through a nozzle 4. It is designed to spray onto the cornea EC of the eye E to be examined through the lens. Further, a pressure sensor 5 is provided to measure the internal pressure of the compression chamber 3. A transparent window 6.7 made of a transparent material is provided in a portion corresponding to the optical path of the compression chamber 3, and the nozzle 4 is attached to the center of the transparent window 6.

On the optical path behind the transparent window 7, half mirrors 9 and 10 are obliquely installed following the objective lens 8, and further an imaging lens 11
, television cameras 12 are arranged in sequence, and the television cameras 1
The output of 2 is connected to a television monitor 13. A lens 14 and an infrared light source 15 for alignment of an infrared light emitting diode or the like are arranged on the optical axis of the reflection side of the half mirror 9, and a lens 16 is arranged on the optical axis of the reflection side of the half mirror 10.
and a light receiving sensor 17 are arranged.

This light receiving sensor 17 is arranged so that the amount of incident light becomes maximum when the cornea EC is in an applanation state. Further, around the transparent window 6, a plurality of light emitting elements 1 for extraocular illumination are provided.
8 is provided. The output of the pressure sensor 5 is sent to the amplifier 19
, and is connected to an MPU (microprocessor unit) 21 via an A/D converter 20.

Further, the output of the reset switch 22 is connected to the MPU 21, and the output of the MPU 21 is connected to the analog switch 23. The analog switch 23 operates to selectively connect the source resistor RL or R)I to the solenoid control circuit 24 that drives the solenoid 1.

Further, the output of the light receiving sensor 17 is connected to the MPU 21 so that even if a certain period of time has elapsed even though the alignment is appropriate, the light receiving sensor for detecting corneal deformation can control the driving of the solenoid and change the pressure range. ing.

Now, to explain the measurement step by step, first, the examiner looks at the eye image E1 to be examined, which is formed on the television camera 12 through the transparent window 6.7, the objective lens 8, and the imaging lens 11, and the infrared light source 1.
Alignment is performed by observing the light source image 15a emitted from the light source 5 and reflected by the cornea EC on the television monitor 13, and when this alignment is completed, the solenoid 1 is automatically or manually energized. Therefore, as mentioned above, solenoid 1
The piston 2 is driven, and the air in the compression chamber 3 is compressed and injected from the nozzle 4 onto the cornea EC, and the cornea EC begins to deform. When the cornea EC is in an applanation state, the amount of light incident on the light receiving sensor 17 becomes maximum, so the pressure inside the compression chamber 3 when the output of the light receiving sensor 17 reaches its peak is directly detected by the pressure sensor 5. Using this internal pressure value, the intraocular pressure is measured from a conversion formula prepared in advance. This is also possible by switching the source resistances RL and RH of the field effect transistors included in the solenoid control circuit 24 that controls the flow using the analog switch 23.

Here, the relationship between the two source resistances RL and H□ is RH>R
Suppose that the source resistance is set to R and the intraocular pressure is measured. In this case, if the intraocular pressure converted based on the result of A/D conversion of the output from the pressure sensor 5 by the A/D converter 20 exceeds the measurement range, the MP
From the next measurement, U21 controls the analog switch 23 to automatically switch the source resistance RH to RL so that more current flows through the solenoid 1.

Furthermore, when the peak output of the light receiving sensor 17 for detecting corneal deformation is not obtained even after a certain period of time has passed even though the alignment is appropriate, the MPU 21 controls the analog switch 23 to automatically change the source resistance RH to RL. so that more current flows through solenoid 1.

Furthermore, if the measured value obtained when the source resistance is set to RL is within the range that can be measured even with the source resistance RH, the C source resistance is automatically set to RH according to a command from the MPU 21, and from the next time onwards, the C source resistance is automatically set to RH. Avoid applying unnecessary shock to the eye E to be examined.

Here, in this embodiment, when the examinee changes, the examiner turns on the reset switch 22 to automatically return the pressurization range to the initial setting before measuring the next examinee. It turns out. The reset switch 22 can also be used as a print switch for a printer or another functional switch such as a switch for clearing past intraocular pressure data, thereby reducing the troublesome operation of the switch. In the case of intraocular pressure measurement, most of the eyes to be examined have normal intraocular pressure, and for eyes with high intraocular pressure, drugs are immediately used to lower the intraocular pressure, so the probability of being able to measure in a low range is quite high. Considering this, this is an extremely important function. In other words, it is more common to select a lower range as an initial setting.

In addition, even in the same subject, the intraocular pressure value may change depending on the eye C to be examined, so if the microswitch 22' detects the movement of the stage, which means switching between the left and right eyes, when the switching of the eye to be measured is detected. , it is desirable to return the measurement range to the initial setting each time.

Here, a display regarding the range selection and a display indicating that measurement is impossible because the range is over are displayed on the display element 25. Note that the display element 25 may also be used as the television monitor 13.

When the source resistance is set to RH, the green light emitting diode lights up, and when the source resistance is switched to RL, the red light emitting diode lights up. If the source resistance cannot be measured with the source resistance set to RH, that is, if the range is over or the alignment is defective, the green light emitting diode will blink at a different frequency, and the source resistance will not be able to be measured with the source resistance set to RL. (defective alignment), the red light emitting diode blinks.

If the range is over, C is displayed as a letter (e.g. rov
e r”) L/ may be used. With the above display, you can confirm that the eye to be examined is in the low intraocular pressure range by lighting up the green light emitting diode when changing the eye to be examined.However, when changing the eye to be examined, it can be confirmed that the reset switch is forgotten and the next measurement is performed in the high intraocular pressure range. can be prevented. Also, if you are measuring in the low intraocular pressure range where the green light emitting diode lights up and you are unable to measure even though the alignment is good, that is, if the range is over, the above-mentioned "rover" will be displayed, and immediately after that, switch to the high intraocular pressure range. and the red light emitting diode lights up.

Also, when measured in a range for low intraocular pressure, the measured value is high < MPU
21, when the next time the range is changed to a range for high intraocular pressure for the same eye to be examined, the lighting of the green light emitting diode is switched to the lighting of the red light emitting diode.

Also, when measured in a microwave for high intraocular pressure, the measured value was low and the MPU
21, when the range is changed to a low intraocular pressure range for the same eye to be examined next time, the lighting of the red light emitting diode is switched to the lighting of the green light emitting diode.

As the display element 25, a liquid crystal element, an electrochromic element, an electrochromic element, a photochromic element, etc. can be effectively used, and these elements may be a single element, an array element, or a matrix element.

Regarding the display, in addition to changing the hue of green and red,
A change in luminance may also be used. By the way, although the visual display has been described above, at least part of the display may be an audio display.

For example, if the range is over, an audio display may be provided, and selection of a range for low intraocular pressure and selection of a range for high intraocular pressure may be indicated by lighting of a green light emitting diode and a red light emitting diode, respectively.

FIG. 2 shows a flowchart of the intraocular pressure measurement executed by the operation of the MPU 21.

First, at the start of measurement, in step 101, the source resistance is switched to RH using the analog switch 23 to set the low intraocular pressure range. Next, in step 102, measurement is performed, and in step 103, it is checked from the measurement result whether or not the range is over. If the range is not exceeded, proceed to step 105; if the range is exceeded, step 104
Then, the analog switch 23 switches the source resistance to RL to set the high intraocular pressure range. In step 105, if the reset switch 22 is on, it is determined that the eye to be examined has changed, and the process returns to step 101. In addition, if the reset switch 22 is off and the process is not completed in step 106, the process returns to step 102 and measurement is performed in the high intraocular pressure range. Furthermore, if it ends in step 106, the measurement ends.

[effect] By showing the information, you can clearly recognize the situation.

[Brief explanation of drawings]

Fig. 1 is a diagram showing an embodiment of the present invention, Fig. 2 is a diagram showing a flowchart, and in the figure, 1 is a solenoid, 2 is a piston, 3 is a compression chamber, and 4 is a diagram showing a flowchart.
is a nozzle, 5 is a pressure sensor, 12 is a television camera, 13
is a TV monitor, 15 is an infrared light source for alignment, 1
7 is a light receiving sensor for detecting corneal deformation, 18 is a light emitting element for external lighting, 19 is an amplifier, 20 is an A/D converter, 21 is an MPU, 22 is a reset switch, and 22' is a microswitch for switching between left and right eyes. , 23 is an analog switch, 2
4 is a solenoid control circuit, and 25 is a display element.

Claims (1)

[Claims] (1) A fluid ejecting means that compresses fluid in a compression chamber and injects the fluid to the cornea of the eye to be examined at a predetermined distance, and detects a predetermined deformation of the cornea of the eye to be examined due to the compressed fluid to determine the intraocular pressure value of the eye to be examined. The fluid ejecting means is equipped with a measuring means for measuring intraocular pressure, and the fluid ejecting means is capable of selecting a first range as a pressurizing range for measuring intraocular pressure, and a second range including a value having a higher degree of pressurizing than the first range. A certain non-contact tonometer includes: a state detecting means for detecting that the measuring means is unable to perform measurement or detecting that the eye to be examined has been replaced; and an output of the state detecting means; The pressurization range for intraocular pressure measurement is set based on at least one of the measured values.
switching means for switching between the range and the second range; and at least one of selective display of the first range and the second range, and a display indicating that the pressurized range at the time of measurement is inappropriate. A non-contact tonometer characterized by having a display means for performing the following functions. (2) The non-contact tonometer according to claim 1, wherein when the state detection means detects that the eye to be examined has been replaced, the switching means returns the pressure range to the normal range.