JPH0554338B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is a non-woven fabric that injects corneal deforming fluid toward the cornea to deform the cornea, and measures intraocular pressure based on the deformation of the cornea. The present invention relates to a contact tonometer, and more specifically, relates to alignment adjustment with respect to the cornea of an eye to be examined.

Prior Art Conventionally, non-contact tonometers include, for example,
The one disclosed in Japanese Patent Publication No. 56-6772 is known. This conventional non-contact tonometer utilizes air pulses as the fluid for corneal deformation. This conventional non-contact tonometer has a fluid ejection nozzle that ejects the air pulse. The axis of this fluid injection nozzle is aligned with the optical axis of the observation optical system for corneal observation. This fluid ejection nozzle operates when the corneal axis connecting the corneal center of curvature and the corneal apex coincides, and when the distance from the corneal center of curvature to the tip of the fluid ejection nozzle is set to a predetermined distance. When alignment is complete, an air pulse is ejected toward the cornea of the eye to be examined. The cornea of the eye to be examined is applanated by the air pulse, and the applanation deformation of the cornea of the eye to be examined is caused by the detection light emitting optical system that emits the corneal deformation detection light for detecting applanation deformation, and the reflected light of the corneal deformation detection light. It is detected by a light-receiving optical system that receives the light. A non-contact tonometer measures intraocular pressure based on a predetermined amount of deformation of the cornea.

Problems to be Solved by the Invention By the way, the invention disclosed in Japanese Patent Publication No. 56-6772 is a method for adjusting the alignment of the corneal axis connecting the center of corneal curvature and the corneal apex with the optical axis of the observation optical system, and for adjusting the center of corneal curvature. It has an alignment adjustment device that adjusts the distance from to the tip of the fluid ejection nozzle (hereinafter referred to as the working distance). The alignment optical system of this conventional alignment adjustment device has an index projection optical system that projects an index spot light toward the cornea. An optical objective lens is used. In this alignment optical system, the objective lens projects the index spot light so as to form an image on the center of curvature of the cornea, and the reflected light by specular reflection of the cornea is returned to the observation optical system via the objective lens. An index spot image is formed on the aiming plate. This conventional non-contact tonometer performs alignment with respect to the cornea based on the sharpness of the index spot image and the position of the index image on the aiming plate.

However, with this conventional alignment adjustment device, only one index image is formed on the aiming plate, and it is difficult to precisely judge its sharpness and position on the aiming plate. There is a problem in that it is difficult to perform accurate alignment.
Furthermore, since the index spot light is imaged at the center of the corneal curvature, there is a drawback that the working distance depends on the corneal curvature radius of the eye to be examined, resulting in an error.

OBJECTS OF THE INVENTION Therefore, a first object of the present invention is to provide a non-contact tonometer that can obtain an accurate working distance without depending on the radius of curvature of the cornea of the eye to be examined. A second object of the present invention is to provide a non-contact tonometer that can serve as both a target projection optical system and a corneal deformation detection optical system for detecting corneal deformation.

Means for Solving the Problems The non-contact tonometer according to the present invention is characterized in that the observation optical system includes an illumination light generating means for illuminating the anterior segment of the eye to be examined, and a light generating means for illuminating the anterior segment of the eye to be examined. It has an objective lens for imaging and an observation means for observing the intermediate image,
The alignment adjustment device has a pair of alignment optical systems disposed at symmetrical positions with respect to the optical axis of the observation optical system so that their respective optical axes intersect at one point on the optical axis of the observation optical system, Each alignment optical system includes an index projection optical system that projects the index spot light generated by the index spot light generation means onto the cornea as a parallel light beam, and a virtual image of the index spot light generated by specular reflection of the cornea of the eye to be examined. and an index detection system that guides the alignment optical system to the observation means via the index projection optical system of the other alignment optical system, and one of the alignment optical systems has corneal deformation detection light generation means that generates corneal deformation detection light. The other side of the alignment optical system is also used as a detection light receiving optical system by having a light receiving means for receiving reflected light based on the corneal deformation of the corneal deformation detection light. However, the anterior segment image illumination light, the index spot light, and the corneal deformation detection light have different wavelength ranges from each other.

Effects According to the non-contact tonometer according to the present invention, when a pair of target spot lights are projected onto the cornea by a pair of target projection optical systems, by specular reflection of the cornea of the eye to be examined,
A virtual image of a pair of index spot lights is formed on the cornea. When the optical axis of the observation optical system passes through the vertex of the cornea and coincides with the center of the cornea, the pair of virtual images are generated at symmetrical positions with respect to the optical axis of the observation optical system. Each alignment optical system is arranged symmetrically with respect to the optical axis of the observation optical system, so when a pair of virtual images are formed at symmetrical positions, the specularly reflected light from the cornea is transmitted to the observation means via the index detection light. is guided to polymerize. Therefore, alignment adjustment with respect to the cornea can be performed by observing the superposition of the pair of virtual images using the observation means.

Examples A non-contact tonometer according to the present invention will be described below with reference to the drawings.

1 to 4 show the optical system of the non-contact tonometer according to the present invention, 1 is an observation optical system, l is
is its optical axis, 2 is the eye to be examined, and 3 is the cornea. The observation optical system 1 includes an anterior segment illumination light generating means 4 that illuminates the anterior segment of the eye 2 to be examined, an objective lens 5 that forms an intermediate image of the anterior segment, and an observation unit 6 that observes the intermediate image. It has The anterior segment illumination light generating means 4 is roughly composed of an incandescent light bulb 7 as an illumination light source, a condenser lens 8, a fixation target plate 9, a collimator lens 10, a half mirror 11, and a green filter 12. ing. The condenser lens 8 has the function of condensing the illumination light from the illumination light source 7 and illuminating the fixation signboard 9. A ring-shaped fixation pattern 9a is formed on the fixation target plate 9, as shown in FIG. The half mirror 11 and the green filter 12 are provided on the optical axis l of the observation optical system 1. The fixation pattern 9a is projected toward the subject's eye 2 by the condenser lens 10 and the half mirror 11 together with _the anterior ocular segment illumination light _P1 .
2, it becomes green light.
The observation means 6 is composed of a focus plate 13 and a contact lens 14, and the anterior segment of the eye 2 to be examined is imaged on the focus plate 13 as an intermediate image by the objective lens 5. Here, the imaging magnification of the objective lens 5 is set to approximately 1/2, so that the entire anterior segment of the eye can be observed. The operator 15 can observe this intermediate image through the eyepiece 14.

A fluid ejection nozzle 16 is provided on the optical axis l of the observation optical system 1, and 16a is the tip of the nozzle. The fluid ejection nozzle 16 has a function of ejecting a cornea deforming fluid toward the cornea 3 from its nozzle tip 16a. The cornea 3 is subjected to applanation deformation into a flat state by this fluid. Here, an air pulse is used for this fluid, and next, the injection conditions of this air pulse will be explained.

The air pulse is emitted when the corneal axis m connecting the corneal curvature center O ₁ and the corneal apex O ₂ is aligned with the optical axis l, and the distance Q from the corneal apex O ₂ to the nozzle tip 16a is ₁ is set to a predetermined distance. The non-contact tonometer is provided with an alignment adjustment device that adjusts the correspondence between the corneal axis m and the optical axis l and adjusts the position from the nozzle tip 16a to the corneal apex _O2 .
This alignment adjustment device includes a pair of first alignment optical system 17 and second alignment optical system 1.
It is roughly composed of 8. The pair of alignment optical systems 17 and 18 are arranged at symmetrical positions with respect to the optical axis l of the observation optical system 1 such that their respective optical axes intersect at a point on the optical axis l of the observation optical system 1. ing.

The first alignment optical system 17 includes an index projection optical system 19 that projects the index spot light onto the cornea 3 as a parallel light beam, and a second alignment optical system 18 that projects a virtual image of the index spot light generated by specular reflection of the cornea of the eye 2 to be examined. and an index detection system 20 that leads to the observation means 6 via an index projection optical system (described later). The second alignment optical system 18 includes an index projection optical system 21 that projects the index spot light onto the cornea 3 as a parallel light beam, and a first alignment optical system 17 that projects a virtual image of the index spot light generated by specular reflection of the cornea of the eye 2 to be examined. and an index detection system 22 that leads to the observation means 6 via an index projection optical system 19. The target projection optical system 19 has a target spot light generating means and a corneal deformation detection light generating means. The index spot light generation means and the corneal deformation detection light generation means are generally composed of a light emitting diode 23 as a common illumination light source, a high pass filter 24, and a wavelength selection filter 25. The high-pass filter 24 has a function of transmitting illumination light having a wavelength of 600 nm or more among the illumination light emitted from the light emitting diode 23. As shown in FIG. 6, the wavelength selection filter 25 has a central portion 2
5a has a device that transmits illumination light having a wavelength range of 700 nm or more among the illumination light emitted from the light emitting diode 23, and the peripheral portion 25b has a wavelength range of 600 nm or more.
It has the function of transmitting illumination light with a wavelength range of 700 nm. Figure 7 shows this wavelength selection filter 2.
5, and the symbol A indicates the peripheral portion 25b.
The symbol B indicates the filter characteristic of the central portion 25a. In addition,
In FIG. 8, symbol C indicates high-pass filter 2.
This shows the filter characteristics of No. 4. The illumination light emitted from the light emitting diode 23 passes through a high-pass filter 24 and a wavelength selective filter 25, and is converted into corneal deformation detection light P ₂ and index spot light P _{3 .}
This is the result. Here, corneal deformation detection light P ₂
has a wavelength range as shown by the symbol D in Figure 9.
Illumination light of 700nm or more is used, and the index spot light
P ₃ has a wavelength range as shown by the symbol E in Figure 9.
Illumination light of 600 nm to 700 nm is used. In addition, in this FIG. 9, the code|symbol F shows the wavelength characteristic of the illumination light emitted from the incandescent light bulb 7. The first alignment optical system 17 is also used as a detection light emitting optical system that emits the corneal deformation detection light P ₂ and includes an objective lens 26 and a half mirror 27 for both alignment and applanation detection. The light emitting diode 23 is placed at the focal point of the objective lens 26, and the corneal deformation detection light P ₂ and the index spot light P ₃ are projected onto the cornea 3 by the objective lens 26 as parallel light beams. The index projection optical system 21 includes a light emitting diode 28 as an illumination light source, a high pass filter 29, an infrared light reflecting mirror 30, a half mirror 31, and an objective lens 32 for both alignment and applanation detection. . The high-pass filter 29 has a function of cutting out illumination light emitted from the light emitting diode 28 with a wavelength range of 600 nm or less, and transmitting light with a wavelength range of 600 nm or more. The infrared light reflecting mirror 30 has a function of reflecting light in a wavelength range of 700 nm or more. The illumination light emitted from the light emitting diode 28 has a wavelength range of 600 nm when passing through the high pass filter 29 and the infrared light reflecting mirror 30.
This serves as an index spot light _P3 of 700 nm to 700 nm. The light emitting diode 28 is provided at the focal point of the objective lens 32, and the index spot light _P3 is projected by the objective lens 32 toward the cornea 3 as a parallel beam of light. As shown in FIG. 2, virtual images i ₁ and i ₂ of the index spot light are formed on the cornea 3 by corneal specular reflection based on parallel beam projection. These virtual images i ₂ and i ₂ are formed at positions symmetrical to each other with the optical axis l as a boundary when the corneal axis m and the optical axis l coincide. Note that the virtual image i ₁ is formed by the index light projection of the first alignment optical system 17 , and the virtual image i ₂ is formed by the index light projection of the second alignment optical system 18 .

The index projection optical system 19, as shown in FIG.
The index projection optical system 23 has a function of guiding the reflected light forming the virtual image i ₂ to the index detection system 22 via the half mirror 27, and the index projection optical system 23 guides the reflected light forming the virtual image i ₁ to the index detection system 22 via the half mirror 31. It has the function of leading to 20. The index detection system 20 includes total reflection mirrors 33, 3
4 and a reflective surface 35a of the beam splitter 35, and the index detection system 22 generally includes total reflection mirrors 36, 37 and a reflective surface 35b of the beam splitter 35. The beam splitter 35 is provided on the optical axis l of the observation optical system 1, has a function of transmitting green light, and has reflective surfaces 35a, 35.
b has a function of reflecting red light.

The virtual images i ₁ and i ₂ of the index spot light are reflected by the reflecting surfaces 35a,
35b toward the direction in which the focus plate 13 exists, and is imaged as an index image _S1 on the focus plate 13 via the half mirror 38, and a part of it is reflected by the half mirror 38. The light is reflected by the light and formed into an image on the light-receiving surface 39 of the detector 39. Note that the detector 39 is arranged at a conjugate position with the focusing plate 13 via a half mirror 38. A pair of index images S ₁ is created when the optical axis l and the corneal axis m coincide, and when the distance Q ₁ from the nozzle tip 16a to the corneal vertex O ₂ is set to a predetermined distance, the first
As shown in Fig. 0, the crosshairs 40 of the focusing plate 13 overlap at the intersection and the resulting image becomes sharp. _O2
When the distance Q ₁ to the point is not set to a predetermined distance, as shown in FIGS. 11 and 12, the pair of index images S ₁ are separated and visually recognized, and the pair of finger images S ₁ is out of focus. Therefore, alignment adjustment can be performed by checking through the observation means 6 whether the pair of index images S ₁ overlap and match with the intersection of the +-shaped line 40. When the pair of index images _S1 are superimposed, the detector 29 detects an air pulse generator (not shown) in which an air pulse indicated by an arrow G is emitted toward the cornea from the drive shaft 16a. It is.

The second alignment optical system 21 has a light receiving means for receiving reflected light based on the corneal deformation of the corneal deformation detection light _P2 , and is also used as a detection light receiving optical system.
In FIG. 4, reference numeral 41 denotes a detector as the light receiving means, and the detector 41 is arranged at a conjugate position with the light emitting diode 28 via the infrared reflecting mirror 30. When detecting corneal deformation, the corneal deformation detection light P ₂ passing through the central portion 25 a of the wavelength selective filter 25 and the index spot light P ₃ passing through the peripheral portion 25 b are projected onto the cornea 3 as parallel light beams by the objective lens 26 . The parallel reflected light is guided to the index projection optical system 21, but the index spot light _P3 passes through the infrared reflection mirror 30 as it is, and only the corneal deformation detection light _P2 is transmitted through the infrared reflection mirror 30. The light is reflected, guided to the detector 41 via the aperture 42, and formed into an image on the light-receiving surface 41a of the detector 41. With this, the cornea 3
The applanation state is detected electrically.

FIG. 13 shows another embodiment of the non-contact tonometer according to the present invention, in which the observation means 6 is configured with relay lenses 43 and 44 that relay the index image S ₁ formed on the focus plate 13. It consists of an image pickup tube (ITV) 45, and instead of being directly observed with the naked eye, it is displayed on a television screen for observation.

In each of the above embodiments, the central axis of the fluid ejection nozzle 16 and the optical axis l of the observation optical system 1 are made to coincide, but the present invention is not necessarily limited to this.

Effects of the Invention As explained above, in the non-contact tonometer according to the present invention, the observation optical system includes an illumination light generating means for illuminating the anterior segment of the eye to be examined, and the anterior segment as an intermediate image.
It has an objective lens for forming an image and an observation means for observing an intermediate image, and an alignment adjustment device aligns each optical axis at a point on the optical axis of the observation optical system at a symmetrical position with respect to the optical axis of the observation optical system. An index projection optical system that has a pair of alignment optical systems arranged so that the index spot lights intersect with each other, and projects the index spot light generated by the index spot light generation means onto the cornea as a parallel light beam. system, and an index detection system that guides a virtual image of the index spot light generated by specular reflection of the cornea of the eye to be examined to the observation means via the index projection optical system of the other alignment optical system. Since the index spot light and corneal deformation detection light are characterized by having different wavelength ranges, it is possible that the optical axis of the observation optical system and the corneal axis connecting the corneal apex and the center of corneal curvature do not match. When the distance from the corneal apex to the nozzle tip is not set to a predetermined distance, a pair of index images corresponding to the virtual image based on corneal specular reflection are confirmed to be separated and out of focus. By checking the polymerization/non-polymerization of a pair of target images through the observation means, it is possible to adjust the alignment between the optical axis of the observation optical system and the corneal axis, and to check whether the corneal axis is aligned with the corneal axis from the tip of the fluid injection nozzle. The effect is that the distance to the vertex can be adjusted at the same time, and the alignment can be adjusted accurately. In addition, the cornea of the eye to be examined is aligned so that the vertex of the cornea of the eye to be examined coincides with the point where the optical axes of the first and second alignment optical systems and the optical axis of the observation optical system intersect. It has the advantage that the working distance does not depend on the radius of curvature.

In addition, one side of the alignment optical system is also used as a detection light emitting optical system that has a corneal deformation detection light generation means that generates a corneal deformation detection light and emits the corneal deformation detection light, and the other side of the alignment optical system is used as a corneal deformation detection light generation means. Since it has a light receiving means for receiving the reflected light based on the corneal deformation and also serves as the detection light emitting optical system, it is compared to a case where a corneal deformation detecting optical system consisting of a detection light emitting optical system and a light receiving optical system is provided separately. This also has the effect of making the configuration more compact.

[Brief explanation of the drawing]

FIG. 1 is a diagram of the optical system of the non-contact tonometer according to the present invention, and is an explanatory diagram for explaining the illumination state of the anterior segment of the eye, and FIG. 2 is a diagram of the index spot light projection state of the optical system shown in FIG. 1. FIG. 3 is an explanatory diagram to explain the reflection path of the base corneal specular reflection light to the index spot light projection of the imaging optical system shown in FIG. 2, and FIG. 4 is an explanatory diagram to explain corneal deformation. An explanatory diagram for explaining the projection state of the detection light, FIG. 5 is a plan view of the solid reference plate shown in FIG. 1, FIG. 6 is a plan view of the wavelength selection filter shown in FIG. 1, and FIG. FIG. 1 is a transmission characteristic diagram of the wavelength selection filter shown in FIG. 1, FIG. 8 is a transmission characteristic diagram of the Ipass filter shown in FIG. Figures 10 to 12, which show the relationship between the wavelength ranges of light and corneal deformation detection light, are diagrams for explaining the action of the alignment adjustment device for a non-contact tonometer according to the present invention during alignment adjustment. , 13th
The figure is an optical system diagram showing another embodiment of the non-contact tonometer according to the present invention. 1... Observation optical system, 2... Eye to be examined, 3... Cornea, 4...
Anterior segment illumination light generation means, 5... Objective lens, 6... Observation means, 17... First alignment optical system, 18... Second alignment optical system, 19, 21... Indicator projection optical system, 20, 22... Indicator detection system , 23... Light emitting diode, 25... Wavelength selective filter, 41... Detector, l... Optical axis, m... Corneal axis, O ₁ ... Center of corneal curvature, O ₂ ... Corneal apex, i ₁ , i ₂ ... Virtual image, S ₁ ...Indicator image.

Claims (1)

[Scope of Claims] 1. The axis of a fluid ejection nozzle that injects a fluid for corneal deformation of the eye to be examined toward the cornea is positioned in a predetermined arrangement relationship with the optical axis of an observation optical system for observing the eye to be examined. The fluid ejection nozzle is provided, and when the alignment of the eye to be examined is completed based on the alignment adjustment device, the fluid is ejected to deform the cornea, and the intraocular pressure is measured based on the deformation of the cornea. The observation optical system is a non-contact tonometer, and the observation optical system includes an illumination light generating means that illuminates the anterior segment of the eye to be examined, an objective lens that forms the anterior segment as an intermediate image, and an objective lens that forms the anterior segment of the eye as an intermediate image. and an observation means for observing, and the alignment adjustment device is arranged at a symmetrical position with respect to the optical axis of the observation optical system such that each optical axis intersects at a point on the optical axis of the observation optical system. a pair of alignment optical systems provided, each of the alignment optical systems comprising: an index projection optical system for projecting the index spot light generated by the index spot light generation means onto the cornea as a parallel light beam; an index detection system that guides a virtual image of the index spot light generated by specular reflection of the cornea during optometry to the observation means via an index projection optical system of the other alignment optical system, one of the alignment optical systems: The other alignment optical system has a corneal deformation detection light generation means that generates a corneal deformation detection light and is also used as a detection and emission optical system that emits the corneal deformation detection light, and the other alignment optical system is configured to detect the corneal deformation of the corneal deformation detection light. The optical system also serves as a detection light receiving optical system, and the anterior eye image illumination light, the index spot light, and the corneal deformation detection light have different wavelength ranges from each other. A non-contact tonometer characterized by: 2. The wavelength range of the anterior segment illumination light is 500 to 600 nanometers, the wavelength range of the index spot light is 600 to 700 nanometers, and the wavelength range of the corneal deformation detection light is 700 nanometers or more. A non-contact tonometer according to claim 1, characterized in that: 3. The index spot light generation means and the corneal deformation detection light generation means include a common illumination light source, and a peripheral portion of the illumination light beam from the common illumination light source having a wavelength range of 600 nanometers to 700 nanometers. and a wavelength-selective filter whose central portion transmits an illumination light beam having a wavelength range of 600 nanometers or more among the illumination light from the common illumination light source. The non-contact tonometer according to item 2. 4. Any one of claims 1 to 3, wherein the objective lens of the observation optical system has an imaging magnification of approximately 1/2 of the anterior segment of the eye to be examined. The non-contact tonometer described in Section 1.