JPH0431694B2 - - Google Patents

Description

Detailed Description of the Invention [Industrial Application Field] The present invention is a non-contact method that deforms the cornea by spraying compressed fluid onto the eye to be examined, and measures the intraocular pressure of the eye to be examined based on the deformed state. This relates to a type tonometer.

[Prior Art] Conventionally, this type of non-contact tonometer generally uses compressed air as the compressed fluid. For example, as disclosed in Japanese Patent Publication No. 54-38437 and Japanese Patent Publication No. 61-321, air in a compression chamber is gradually compressed by a piston driven by a solenoid, and this compressed air is sent to a nozzle. The solenoid is injected onto the cornea of the eye to be examined, the time it takes for the cornea to reach an applanation state is measured, and then the power to the solenoid is turned off. However, even after the power is turned off, the piston further compresses the air in the compression chamber due to inertia, so even after measurement, unnecessary compressed air is injected into the cornea of the subject's eye, causing unnecessary shock to the subject. It has the disadvantage of giving

In order to compensate for this drawback, a conventional example has been considered in which a plurality of measurement ranges are prepared in advance and a means is provided for switching the ranges according to the eye to be examined.

[Problems to be Solved by the Invention] However, in the above-mentioned conventional example, when a certain eye to be examined is measured in a measurement range for low intraocular pressure,
If the intraocular pressure of the eye to be examined is higher than the range, resulting in an overrange, and the next measurement is switched to the measurement range for high intraocular pressure, even if the eye to be measured becomes a different eye, it will not be possible to press the specific range switch. Unless the measurement range for low intraocular pressure is reached, the measurement will not return to the measurement range for low intraocular pressure, and the measurement will be performed from the beginning in the measurement range for high intraocular pressure. If the pressure is too high, excess air will be supplied to the subject's eye, causing discomfort to the subject.

[Object of the Invention] An object of the present invention is to provide a non-contact tonometer in which a detection means detects that the eye to be examined has changed, and always starts measurement from an initially set measurement range.

[Summary of the invention] The gist of the present invention for achieving the above object is as follows:
a fluid ejecting means for ejecting fluid to the cornea of the eye to be examined;
In a non-contact tonometer that has a detection means for detecting a predetermined deformation of the cornea due to the ejected fluid and calculates an intraocular pressure value using a corneal deformation signal from the detection means, A non-contact device characterized by having a switching means for automatically switching the measurement range, and a return means for returning the measurement range to a predetermined measurement range by the switching means in response to an operation performed when the eye to be examined changes. It is a type tonometer.

[Embodiments of the Invention] The present invention will be described in detail based on illustrated embodiments.

FIG. 1 shows a configuration diagram of a non-contact tonometer according to the present invention, in which a piston 2 driven by a solenoid 1 enters a compression chamber 3 to compress the air in the compression chamber 3. Air is blown onto the cornea Ec of the eye E through the nozzle 4.
Further, a pressure sensor 5 is provided to measure the internal pressure of the compression chamber 3. Transparent windows 6 and 7 made of a transparent material are provided in a portion of the compression chamber 3 corresponding to the optical path L, and the nozzle 4 is attached to the center of the transparent window 6. On the optical path L behind the transparent window 7, half mirrors 9 and 10 are diagonally installed following the objective lens 8, and an imaging lens 11 and a television camera 12 are arranged in sequence, and the output of the television camera 12 is transmitted to the television. It is connected to the monitor 13. A lens 14 and an infrared light source 15 for alignment such as an infrared light emitting diode are arranged on the optical axis of the reflection side of the half mirror 9, and a lens 16 and a light receiving sensor are arranged on the optical axis of the reflection side of the half mirror 10. 1
7 is placed. This light receiving sensor 17
They are arranged so that the amount of incident light is maximized when Ec is in the applanation state. Further, a plurality of light emitting elements 18 for extraocular illumination are provided around the transparent window 6. The output of the pressure sensor 5 is sent to the amplifier 1
9. Connected to an MPU (microprocessor unit) 21 via an A/D converter 20. Further, the output of a reset switch 22 is connected to the MPU 21, and the output of the MPU 21 is connected to an analog switch 23. analog switch 23
is the solenoid control circuit 2 that drives the solenoid 1.
The source resistor RL or RH is selectively connected to the source resistor 4.

First, the examiner uses the transparent windows 6, 7, the objective lens 8,
Alignment is performed by observing the subject image Ea formed on the television camera 12 via the imaging lens 11 and the light source image 15 emitted from the infrared light source 15 and reflected by the cornea Ec on the television monitor 13. When this alignment is completed, the solenoid 1 is energized automatically or manually. Therefore, as mentioned above, the piston 2 is driven by the solenoid 1, and the compression chamber 3
The air inside is compressed and injected from the nozzle 4 onto the cornea Ec, and the cornea Ec begins to deform. and corneal Ec
When it reaches the 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, and this internal pressure is The intraocular pressure is measured using a conversion formula prepared in advance using the value of .
In addition, the measurement range is switched by the source resistance RL of the field effect transistor included in the solenoid control circuit 24 that controls the current flowing to the solenoid 1.
This is possible by switching the RH using the analog switch 23.

Here, the relationship between the two source resistances RL and RH is
Assume that RH>RL and that the source resistance is set to RH 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 MPU 21 switches the analog switch from the next measurement. 23 to automatically switch the source resistance RH to RL to allow more current to flow through the solenoid 1.

Conversely, if the result obtained when the source resistance is set to RL is within the range that can be measured even with the source resistance RH, the source resistance is automatically set to RH by a command from the MPU21, and the next time From then on, 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
The measurement range will be automatically returned to the initial setting before the measurement of the next subject. Reset switch 22
For example, by serving as a switch for other functions such as a switch for printing to a printer or a switch for clearing past intraocular pressure data, the troublesome operation of the switch can be alleviated. 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 to be examined, so if the micro switch that detects the movement of the stage, which means switching between the left and right eyes, detects the switching of the eye to be measured, It is desirable to return the measurement range to the initial setting each time.

These actions are performed by operating the MPU 21 according to the flowchart for measuring intraocular pressure shown in FIG. In other words, the step starts when the measurement starts.
101, the source resistance is changed by analog switch 23.
Switch to RL to set low intraocular pressure range. Next, in step 102, measurement is performed, and in step 103, it is checked from the measurement results whether or not there is an overrange. If it is not over range, the process goes to switch 105, and if it is over range, in step 104, the analog switch 23 switches the source resistance to RH 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. Further, if the reset switch 22 is off and the process is not completed at step 106, the process returns to step 102 and measurement is performed in the high intraocular pressure range. Furthermore, if it ends at step 106, the measurement ends.

[Effects of the Invention] As explained above, the non-contact tonometer according to the present invention has a means for returning the measurement range to the initial setting in accordance with the operation performed when the eye to be examined changes, so that the non-contact tonometer according to the present invention always performs the initial Measurements are now performed in the same measurement range, and there is no need to apply extra shock to the intraocular pressure of the subject's eye when measuring in a higher measurement range. Further, by using a switch having another function, such as a print switch of a printer, as the return means, the troublesome operation of the switch can be reduced.

[Brief explanation of drawings]

The drawings show an embodiment of a non-contact tonometer according to the present invention, and FIG. 1 is a block diagram of the present invention, and FIG. 2 is a flowchart. 1 is a solenoid, 2 is a piston, 3 is a compression chamber, 4 is a nozzle, 5 is a pressure sensor, 6 is an optical member, 9 and 10 are half mirrors, 11 is an imaging lens, 12 is a television camera, and 13 is a television monitor ,
15 and 18 are light sources, 17 is a light receiving sensor, 20 is an A/D converter, 21 is an MPU, 22 is a reset switch, 23 is an analog switch, and 24 is a solenoid control circuit.

Claims (1)

[Scope of Claims] 1. A fluid ejecting means for ejecting a fluid onto the cornea of the eye to be examined, and a detection stage for detecting a predetermined deformation of the cornea due to the ejected fluid, the corneal deformation from the detecting means being A non-contact tonometer that calculates an intraocular pressure value using a signal includes a switching means that automatically switches the measurement range of the intraocular pressure in the eye to be examined, and a switching means that changes the measurement range according to an operation performed when the eye to be examined changes. A non-contact tonometer characterized by having a return means for returning the tonometer to a predetermined measurement range. 2. The non-contact tonometer according to claim 1, wherein the control means performs the return operation based on the output of a discriminating means for determining left and right eyes of the subject. 3. The non-contact tonometer according to claim 1, wherein the control means performs the return operation by inputting a print switch that prints measured values or a clear switch that erases past measured values.