JPH0716209A - Noncontact tonometer - Google Patents

Abstract

PURPOSE:To provide a noncontact tonometer which can uniform the pressure distribution of gas injected into an examined eye out of a nozzle. CONSTITUTION:The meter is equipped with a light source 1 lighting an examined eye E, a cornea deformation detecting section 2 as a receiving means receiving reflected light from the examined eye E, and with a gas injection means 10 deforming the examined eye by blowing air against the examined eye E. The gas injection means 10 is made up of a cylinder 11, a nozzle which is connected to the cylinder 11 while being faces to the examined eye E, a filter 12a which is disposed within the nozzle 12 to uniform the injection pressure distribution of air, a piston 13 pushing air within the cylinder 11 out of the nozzle 12, and of a rotary solenoid 14 as a drive means driving the piston 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention optically detects deformation of an eye to be inspected when a gas is jetted to the eye to be inspected.
Regarding a non-contact tonometer that measures the intraocular pressure of the eye to be examined in a non-contact manner,
In particular, it relates to the improvement of the gas injection device part.

[0002]

2. Description of the Related Art A non-contact tonometer of this type is a light source for illuminating an eye to be examined, a light receiving means for receiving reflected light from the eye to be examined, and a gas to be blown onto the eye to deform the eye to be examined. A gas injection device is provided, and the deformation of the eye to be inspected when gas is blown by the gas injection device is detected by the light receiving means to measure the intraocular pressure.

The gas injection device comprises a cylinder, a nozzle connected to the cylinder and facing the eye to be inspected, a piston for pushing out the gas in the cylinder from the nozzle, and a solenoid for driving the piston. The gas compressed by Pinton in the cylinder is jetted from a cylindrical nozzle.

[0004]

However, since the above-mentioned conventional non-contact tonometer uses a simple cylindrical nozzle, if the shape or arrangement of the cylinder or piston is not symmetrical with respect to the nozzle. The flow of gas flowing in the nozzle is biased.

When the gas flow in the nozzle is biased, the pressure distribution of the gas jetted to the subject's eye is not uniform, and the cornea deforms in a distorted shape, so that the reflected light from the subject's eye is detected. There is a problem that the waveform of the corneal deformation detection signal obtained by doing so is disturbed and the measurement accuracy is lowered.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and provides a non-contact tonometer capable of making the pressure distribution of the gas ejected from the nozzle toward the eye to be inspected uniform. The purpose is to provide.

[0007]

In order to achieve the above-mentioned object, a non-contact tonometer according to the present invention is equipped with a gas injection device for deforming the eye by blowing gas onto the eye. In a non-contact tonometer that optically measures the eye pressure by optically detecting the deformation of the eye to be inspected when a gas is blown by the device, the gas injection device has a gas passage portion for guiding the gas toward the eye. However, the gas passage portion has a means for making the distribution of the injection pressure of the gas uniform.

[0008]

According to the non-contact tonometer of the present invention, the jet pressure distribution equalizing means eliminates the bias in the flow of the gas passing through the gas passage portion, and makes the pressure distribution of the gas jetted to the eye to be examined uniform. Become.

[0009]

Embodiments of the non-contact tonometer according to the present invention will be described below. First Embodiment FIG. 1 is an explanatory diagram showing a measurement unit and a gas injection device portion of a non-contact tonometer according to a first embodiment of the present invention.

The apparatus shown in FIG. 1 includes a light source 1 for illuminating an eye E to be examined.
A corneal deformation detection unit 2 that receives reflected light from the eye E to detect a deformed state of the cornea;
Here, the gas injection device 10 that deforms the eye to be inspected by blowing air is provided. The alignment detector 3 outputs an alignment completion signal when the device is accurately aligned with the eye by the reflected light from the eye.

The gas injection device 10 includes a cylinder 11 and a nozzle 12 which is connected to the cylinder 11 and faces the eye E to be inspected.
And a piston 13 for pushing out the air in the cylinder 11 from the nozzle 12, and a rotary solenoid 14 as a driving means for driving the piston 13. A pressure sensor 16 for detecting the pressure inside the cylinder is provided inside the cylinder 11.

The signal from the measurement switch 7 for instructing the start of the measurement and the output signal from the alignment detection unit 3 are directly input to the central processing unit 20, and the output from the corneal deformation detection unit 2 and the pressure sensor. The outputs from the pressure detection unit 4 which receives the signal from the A.D.
Is input to the central processing unit 20 as a digital signal via.

The nozzle 12 functions as a gas passage portion for guiding air toward the eye E to be inspected, and at the base end thereof is a porous member as shown in FIG. 2 as a means for making the injection pressure distribution of gas uniform. Filter 12a is provided. Filter 1
The shape of each hole of 2a may be a square as shown in FIG. 2 (a) or a circle as shown in (b).

The nozzle 12 is generally provided so that its axial direction intersects with the moving direction of the piston, as shown in FIG. Therefore, the air flow pushed by the piston 13 collides with the inner wall of the cylinder 11 as shown by the arrow in FIG. 3, is diffused in various directions, and then enters the nozzle 12. Here, if the nozzle 12 is not provided with the filter 12a, the air flow in the nozzle 12 becomes uneven, and the pressure distribution of the injected air is not uniform.

In the apparatus of the first embodiment, since the filter 12a is provided in the nozzle 12, this filter 12a
By passing through, the bias of the air flow flowing in the nozzle 12 can be eliminated, and the pressure distribution of the injected air can be made uniform.

The central processing unit 20 drives the solenoid drive unit 17 after turning on the light source 1 and receiving the alignment completion signal from the alignment detection unit 3 or the measurement start signal from the measurement switch 7. A signal is output to cause a predetermined current to flow in the rotary solenoid 14 to move the piston 13 and compress the air in the cylinder 11. The compressed air is ejected toward the eye E from the nozzle 12 through the filter 12a.

When air is jetted to the eye E at a predetermined jet pressure, the cornea of the eye E is deformed. Information regarding the degree of corneal deformation is input to the central processing unit 20 via the A / D converter 5 from the corneal deformation detection unit 2 that receives the light flux emitted from the light source 1 and reflected by the eye E to be inspected. The central processing unit 20 uses a conversion formula prepared in advance based on the information on the deformation of the cornea and the information on the injection pressure input from the pressure sensor 16 via the pressure detection unit 4 and the A / D converter 6. The intraocular pressure of the eye E to be examined is calculated.

The filter 12a is preferably made of a transparent material which is colorless and transparent. This is because, in order to make the alignment optical system have a simple structure, it is generally desirable to make the alignment light incident on the eye E coaxial with the nozzle 12.

The position at which the filter 12a is provided is not limited to the base end portion of the nozzle 12 as in the above-described embodiment, but may be the intermediate portion as shown in FIG. 4A or the position as shown in FIG. It may be provided at the end portion on the side of the eye E to be inspected, or may have a predetermined length as shown in FIG.

Further, as the structure of the filter 12a,
Not only uniform holes may be provided, but holes having different sizes may be arranged as shown in FIG. 5A, or a chevron-shaped protrusion may be provided inside as shown in FIG. 5B. According to the configuration as shown in FIG. 5A, the deviation of the air flow unique to the device can be effectively made uniform, and the configuration of FIG. 5B can also make the air flow uniform.

FIG. 6 is an explanatory view showing a gas injection device portion of a non-contact tonometer according to Embodiment 2 of the present invention. In this embodiment, a filter 12c as an injection pressure distribution equalizing means is attached to a nozzle fixing member 12b that fixes the nozzle 12 in the cylinder 11. That is, in this embodiment, the filter 12c is arranged outside the nozzle 12 and in the gas passage portion for guiding the air toward the subject's eye E.

The shape of the filter 12c of the second embodiment is shown in FIG.
As shown in FIG. 3, it is cup-shaped as a whole, and its bottom surface is formed in a porous shape. Regarding the shape of the holes, Example 1
The same modified example as can be considered. The operation and filter effect in the second embodiment are similar to those in the first embodiment.

In addition, in order to clean the air jetted to the eye to be inspected, the filter of each of the above-mentioned embodiments may be provided with an air cleaning action. Further, instead of the filter of the above-mentioned embodiment, a member having a mesh-shaped cross section may be used.

[0024]

As described above, according to the present invention, it is possible to make the ejection pressure distribution of the gas ejected toward the subject's eye uniform, and the subject's eye is uniformly deformed at the time of measuring the intraocular pressure. As a result, the waveform of the corneal deformation detection signal is adjusted, and the measurement accuracy of intraocular pressure measurement can be improved.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a first embodiment of a non-contact tonometer according to the present invention.

FIG. 2 is a plan view showing the structure of a filter.

FIG. 3 is an explanatory diagram showing a flow of air in a cylinder.

FIG. 4 is an explanatory diagram showing a modification of the position of the filter provided in the nozzle.

FIG. 5 is a plan view showing the structure of a filter.

FIG. 6 is a schematic diagram showing Embodiment 2 of the non-contact tonometer according to the present invention.

FIG. 7 is a perspective view showing a configuration of a filter according to a second embodiment.

[Explanation of symbols]

 E Eye to be inspected 10 Gas injection device 11 Cylinder 12 Nozzle 12a Filter 13 Piston

Claims (4)

[Claims] 1. A gas ejecting device for deforming the eye to be inspected by blowing gas onto the eye to be inspected, wherein the deformation of the eye to be inspected when the gas is ejected from the gas injecting device is optically detected. In a non-contact tonometer for measuring pressure, the gas injection device has a gas passage portion for guiding gas toward the eye to be inspected, and the gas passage portion is a means for making the injection pressure distribution of the gas uniform. A non-contact tonometer, comprising: 2. The non-contact tonometer according to claim 1, wherein the injection pressure distribution uniformizing means is a porous filter. 3. The non-contact tonometer according to claim 2, wherein the filter has an air cleaning function. 4. The non-contact tonometer according to claim 2, wherein the filter is made of a material that transmits light.