JPH01300928A - Tonometer - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention involves blowing air onto the cornea of the eye to be examined to applanate the cornea, and determining intraocular pressure from the pressure when a predetermined applanation state is reached. The present invention relates to a non-contact tonometer.

[Prior Art] Conventional tonometers of this type generally utilize the corneal reflection of the eye to be examined.1. However, since this alignment is delicate and it is difficult to improve its accuracy, there is a problem in that it is difficult to obtain accurate measurement values.

In addition, when automatic alignment is performed electrically, it is difficult to follow the rapid movement of the eye due to the large capacity of the device.1. There is also the problem of

[Object of the Invention] In order to improve such problems, the object of the present invention is to provide a tonometer that can perform the necessary precise IW alignment using an automatic alignment mechanism with small moving parts and good responsiveness. It's about doing.

[Summary of the Invention] The gist of the present invention for achieving the above-mentioned object is to provide an alignment detection means for detecting the alignment state with respect to the eye to be examined using corneal reflected light, a nozzle for blowing airflow to the eye to be examined, and a pressure sensor for detecting internal pressure. a pressure chamber equipped with a sensor;
a pressurizing device for generating airflow; a flexible tube connecting the pressure chamber and the pressurizing device; and an eye for optically detecting deformation of the cornea and determining intraocular pressure based on the output of the pressure sensor. a pressure measuring means; a movable part including the pressure chamber except for the pressurizing device;
The tonometer is characterized by comprising a drive control section that performs alignment by three-dimensionally driving the movable section using a signal from the alignment detection means.

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

FIG. 1 shows a first embodiment, in which compressed air from a pressurizing device 1 is guided into a pressure chamber 3 through a flexible tube 2, and an air flow is blown from a nozzle 4 onto the cornea Ec of the eye E. There is. An optical member 5 with a nozzle 4 attached to the front of the pressure chamber 3, an objective lens 6 at the rear, a small mirror 7 inside, and a pressure sensor 8 for measuring the air pressure inside the pressure chamber 3 on the side wall. It is provided. A lens 9 and an alignment light source 10 are provided on the side entrance side of the small mirror 7, and a light splitting member 11, 12 is provided obliquely behind the objective lens 6.
．． Television cameras 13 are arranged, a lens 14 and a light receiving element 15 are arranged in the reflection direction of the light splitting member 11, and the output of the television camera 13 is connected to a television monitor (not shown) for checking alignment. Further, an imaging lens 16 and a light receiving element 17 are provided in the reflection direction of the light splitting member 12. Pressure chamber 3, lens 9, light source 10, light splitting member 1
1. The part including the lens 14 and the light receiving element 15 is an integrated movable part 18, and this movable part 18 is connected to the output of the light receiving element 17 for automatic alignment when the eye E is not in a predetermined position. x, Y
, are three-dimensionally driven in the Z direction.

In use, rough alignment of the device with respect to the eye E to be examined is performed manually or automatically.

Precise alignment is such that the light beam emitted from the light source 10 passes through the small mirror 7 and the nozzle 4 and is projected onto the cornea Ec at an angle l.
l! i! The corneal reflected light is reflected by the EC and sent to the optical member 5.
．． This is performed by receiving light at the light receiving element 17 via the objective lens 6, the light splitting member 12, and the imaging lens 16, and moving the movable section 18 by the drive control section 19. In this case, the light receiving element 17 is composed of a plurality of elements, for example, and outputs an alignment detection signal to the drive control section 19 depending on the state of image formation of the corneal reflected light on the light receiving element 17.

When this automatic alignment is completed, the pressurizing device 1 is activated to generate compressed air, which is guided to the pressure chamber 3 and blown onto the eye E through the nozzle 4 to applanate the cornea Ec. . When the cornea Ec reaches a predetermined applanation state, the corneal reflection image by the light source 10 is transmitted to the optical member 5, the objective lens 6, the light splitting member 11. If the image is formed on the light receiving element 15 via the lens 14 and the air pressure in the pressure chamber 3 when the output of the light receiving element 15 reaches the maximum is measured by the pressure sensor 8, the intraocular pressure of the eye E to be examined can be determined from this air pressure. A value is required.

Since the pressure chamber 3 and the pressurizing device 1 are connected by the flexible tube 2, even if the movable part 18 moves for alignment, the pressurizing device 1 can be maintained in a fixed state. Furthermore, even if the movable part 18 moves, the light beam that exits the objective lens 6 and enters the imaging lens 16 is a parallel light beam, so the corneal reflected image does not move.
Since the pressure transmitted by the nozzle 4 may not be constant, it is desirable that the air pressure in the pressure chamber 3 in which the nozzle 4 is provided is detected by the pressure sensor 8.

FIG. 2 shows a second embodiment, in which the same reference numerals as in the first embodiment represent the same members. In this second embodiment, a nozzle 4 of a pressure chamber 3 connected to a pressurizing device 1 by a flexible tube 2 is provided through the center of an objective lens 20 provided in front of the pressure chamber 3. , an optical member 21 is provided at the rear of the pressure chamber 3. An imaging lens 22, an oblique light splitting member 23, and a light receiving element 24 are arranged behind the optical member 21, and an alignment light source 25 is provided on the incident side of the light splitting member 23. In addition to the pressure chamber 3, the movable part 26 includes an intraocular pressure 'A11 light source 27 provided obliquely with respect to the eye E to be examined, a light projecting lens 28, a light receiving lens 29 that receives corneal reflected light, and a light receiving lens 29 that receives corneal reflected light. An element 30 is provided, and the movable part 26 is three-dimensionally driven by a drive control part 3j based on an alignment detection signal from the light receiving element 24.

In this second embodiment, light from an alignment light source 25 is projected onto the cornea Ee of the eye E through a light splitting member 23, an imaging 1/lens 22, and an objective 1/lens 20, and its corneal reflection is The light is received by the light receiving element 24 I7, and the drive control unit 31 does not move the movable part 26, so that alignment is automatically performed. When this alignment is completed, the pressurizing device 1 is activated as in the previous embodiment. When activated, the airflow reaches nozzle 4.
is sprayed onto the eye E to deform the corner 119Ee.

Corner I+! 2. When the EC undergoes a certain deformation, the output of the light-receiving element 30 becomes maximum, and the air pressure in the pressure chamber 3 at that time is measured by the pressure sensor 8 to determine the intraocular pressure.

In the case of this embodiment as well, the objective 1/lens 20 and the imaging lens 22
Since there is a parallel beam of light between them, the position of the image does not change even if the movable part moves. If it is not a flat or linear beam, the imaging 1/lens 22, the light splitting member 23, the light receiving element 24. The light source 25 may be moved integrally.

Note that it is preferable that the movable part 26, which is three-dimensionally driven by the drive control part 31, be limited to only the pressure chamber 3 and the members that need to be moved together with it, so that it can easily respond to the rapid movement of the eye. However, since considerable responsiveness can be obtained by separating at least only the heavy pressurizing device 1, the members included in the movable portion 26 may be modified in various ways.

[Effect of the invention] As explained above, the tonometer according to the present invention has a large weight S
The pressurizing device and the pressure chamber are connected with a flexible tube12, the movable parts including the pressure chamber and the necessary optical system are made lightweight, and alignment is performed by moving only the movable parts17, so that the eye It becomes possible to obtain an automatic alignment mechanism with good responsiveness that can follow fast movements.

[Brief explanation of the drawing]

The drawings show embodiments of the tonometer according to the present invention, and FIG. 1 is a block diagram of the embodiment [1], and FIG. 2 is a block diagram of the second embodiment. 11-dimensional pressure device, 2 is a flexible tube, 3 is a pressure chamber, 4 is a nozzle, 6.20 is an objective lens, 10.25.27 is a light source, 7 is a small mirror, 8 is a pressure sensor, 11 .12.23
is a light splitting member, 13 is a television camera, 15.17.2
4.30 is the light receiving element, 16.22 is the imaging 1/lens, 18
．． 26 is a movable part, and 19.31 is a drive control part. Patent applicant Canon Co., Ltd.

Claims (1)

[Claims] 1. Alignment detection means for detecting the alignment state with respect to the eye to be examined using corneal reflected light, a pressure chamber equipped with a nozzle for blowing airflow onto the eye to be examined and a pressure sensor for detecting internal pressure, and a pressurizing device for generating the airflow. a flexible tube connecting the pressure chamber and the pressurizing device; an intraocular pressure measuring means for optically detecting deformation of the cornea and determining the intraocular pressure based on the output of the pressure sensor; and the pressurizing device. A tonometer characterized by comprising: a movable part including the pressure chamber, and a drive control part that performs alignment by driving the movable part three-dimensionally based on a signal from the alignment detection means.