JP3347820B2 - Non-contact tonometer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for optically detecting deformation of a subject's eye when a gas is injected into the subject's eye.
Regarding a non-contact tonometer for measuring 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.

[0002]

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

[0003] The gas ejecting apparatus includes a cylinder, a nozzle connected to the cylinder and facing the eye to be inspected, a piston for pushing gas in the cylinder from the nozzle, and a solenoid for driving the piston. The gas compressed by the pin ton in the cylinder is injected from a cylindrical nozzle.

[0004]

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

[0005] When the gas flow in the nozzle is deviated, the pressure distribution of the gas injected into the eye becomes uneven and the cornea deforms in a distorted shape, so that the reflected light from the eye is detected. Therefore, there is a problem that the waveform of the corneal deformation detection signal obtained by this operation is disturbed, and the measurement accuracy is reduced.

[0006]

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

[0007]

In order to achieve the above object, a non-contact tonometer according to the present invention includes a gas ejecting device for deforming an eye to be inspected by blowing gas to the eye to be inspected. In a non-contact tonometer for measuring intraocular pressure by optically detecting deformation of an eye to be inspected when gas is blown by a device, a gas ejecting device has a gas passage for guiding gas toward the eye to be inspected. The gas passage has a filter in which holes for making the gas injection pressure distribution uniform are formed .

[0008]

SUMMARY OF] According to a non-contact tonometer according to the present invention, the gas passing through the gas passage portion is, injection pressure disposed in the passage on the
By passing through the holes in the filter that equalizes the force distribution.
Thus, the flow of the gas is not biased, and the pressure distribution of the gas injected to the eye to be examined becomes uniform.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the non-contact tonometer according to the present invention will be described below. FIG. 1 is an explanatory diagram illustrating a measuring unit and a gas ejecting unit of the non-contact tonometer according to the first embodiment of the present invention.

FIG. 1 shows a light source 1 for illuminating an eye E to be examined.
A corneal deformation detecting unit 2 that receives reflected light from the eye E and detects a corneal deformation state;
Here, a gas ejection device 10 that deforms the subject's eye by blowing air is provided. Note that the alignment detection unit 3 outputs an alignment completion signal when the apparatus is accurately aligned with the subject's eye by the reflected light from the subject's eye.

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

The signal from the measurement switch 7 for instructing the start of the measurement and the output signal from the alignment detecting section 3 are directly input to the central processing unit 20, and the output from the corneal deformation detecting section 2 and the pressure sensor Outputs from the pressure detection unit 4 receiving signals from the A / D converters 5 and 6
Is input to the central processing unit 20 as a digital signal.

The nozzle 12 functions as a gas passage for guiding air toward the eye E, and has a porous end at a base end thereof as shown in FIG. Filter 12a is provided. Filter 1
The shape of each hole 2a may be a square as shown in FIG. 2A or a circle as shown in FIG. 2B.

The nozzle 12 is generally provided so that its axial direction intersects the direction of movement 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 and is diffused in various directions, and then enters the nozzle 12. Here, if the filter 12a is not provided in the nozzle 12, the flow of air in the nozzle 12 will be uneven, and the pressure distribution of the injected air will not be uniform.

In the apparatus of the first embodiment, since the filter 12a is provided in the nozzle 12, this filter 12a
, It is possible to eliminate the bias of the airflow flowing through the nozzle 12 and to make the pressure distribution of the injected air uniform.

The central processing unit 20 drives the solenoid driving unit 17 after turning on the light source 1 and receiving an alignment completion signal from the alignment detecting unit 3 or after receiving a measurement start signal from the measuring switch 7. A signal is output to supply a predetermined current to the rotary solenoid 14, and the piston 13 is moved to compress the air in the cylinder 11. The compressed air is jetted from the nozzle 12 toward the eye E 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 on the degree of corneal deformation is input to the central processing unit 20 via the A / D converter 5 from the corneal deformation detecting unit 2 which receives the light beam emitted from the light source 1 and reflected by the eye E. The central processing unit 20 uses a conversion formula prepared in advance, based on information about the deformation of the cornea and information about 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 is calculated.

The filter 12a is desirably made of a colorless and transparent material that transmits light. This is because, in order to make the alignment optical system simple, it is generally desirable that the alignment light be incident on the subject's eye E coaxially with the nozzle 12.

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

Further, the configuration of the filter 12a is as follows.
In addition to providing uniform holes, holes having different sizes may be arranged as shown in FIG. 5A, or a mountain-shaped ridge may be provided inside as shown in FIG. 5B. According to the configuration as shown in FIG. 5A, the bias of the air flow peculiar to the apparatus 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 ejecting part of a non-contact tonometer according to a second embodiment of the present invention. In this embodiment, a filter 12c as an injection pressure distribution uniforming means is attached to a nozzle fixing member 12b for fixing the nozzle 12 in the cylinder 11. That is, in this embodiment, the filter 12c is disposed outside the nozzle 12 and in a gas passage for guiding air toward the eye E to be examined.

The shape of the filter 12c of the second embodiment is shown in FIG.
As shown in the figure, the whole is cup-shaped, and the bottom surface is formed in a porous shape. For the shape of the hole, see Example 1.
A modification similar to the above can be considered. The operation and the effect of the filter in the second embodiment are the same as those in the first embodiment.

In order to clean the air jetted to the eye to be examined, the filters of the above-described embodiments may have an air purifying function. Further, a member having a mesh-shaped cross section may be used instead of the filter of the above-described embodiment.

[0024]

As described above, according to the present invention, the gas ejected toward the eye to be examined has a hole formed therein.
By passing the gas through the filter, the injection pressure distribution of this gas can be made uniform, and the eye to be examined is uniformly deformed during the measurement of the intraocular pressure, whereby the waveform of the corneal deformation detection signal is adjusted and the measurement accuracy of the intraocular pressure measurement is improved. Can be improved.

[Brief description of the drawings]

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

FIG. 2 is a plan view showing a configuration 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 a filter provided in a nozzle.

FIG. 5 is a plan view showing a configuration of a filter.

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

FIG. 7 is a perspective view illustrating 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)

(57) [Claims] A gas injection device for deforming the eye by blowing gas to the eye to be inspected, and optically detecting deformation of the eye to be inspected when the gas is blown by the gas injection device. In a non-contact tonometer for measuring pressure, the gas ejecting device has a gas passage portion for guiding gas toward the eye to be examined, and the gas passage portion has a hole for making a gas ejection pressure distribution uniform. A non-contact tonometer characterized by having a filter formed with . 2. The filter according to claim 1 , wherein said filter has a plurality of said holes.
2. The non-contact tonometer according to claim 1 , wherein the plurality of holes have different sizes . 3. A non-contact tonometer according to claim 1 or 2, wherein the filter has an air cleaning function. Wherein said filter is a non-contact tonometer according to claim 1 or 2, characterized in that it is formed of a material that transmits light.