JPH02232032A - Optical system for ophthalmologic equipment used for measuring both cornea shape and intraocular pressure - 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 is capable of measuring the intraocular pressure of an eye to be examined in a non-contact manner, and
This article relates to the optical system of an ophthalmological instrument that can measure the corneal shape and intraocular pressure of the subject's eye. (Prior art) Intraocular pressure measuring means for non-contactly measuring the intraocular pressure of the eye to be examined include, for example, Japanese Patent Publication No. 54-38437 and Japanese Patent Application No. 59 Sho.
A tonometer disclosed in Japanese Patent Publication No. 242279 or Japanese Patent Publication No. 62-30768 is known. The device disclosed in Japanese Patent Publication No. 54-38437 discharges fluid toward the cornea of the subject's eye according to a known pressure-hour function, electrically detects the applanation state of the cornea, and flattens the cornea from the start of fluid discharge. This method measures the time interval between the two eye movements and the intraocular pressure of the subject's eye. Furthermore, the device disclosed in Japanese Patent Application No. 59-242279 discharges fluid into the cornea of the subject's eye, detects the pressure of the discharged fluid, and uses the pressure as a parameter to electrically detect the amount of light reflected from the cornea. , the intraocular pressure is measured from the detected pressure of the fluid when the cornea is deformed into a predetermined shape. Furthermore, the device disclosed in Japanese Patent Publication No. 62-30768 sprays fluid at a constant pressure onto the cornea and irradiates the cornea with corneal applanation detection light, and the light intensity of the corneal applanation detection light is based on the specular reflection of the cornea before and after the fluid is sprayed. It measures intraocular pressure based on changes. On the other hand, as means for measuring the radius of curvature of the cornea of the eye to be examined, there are methods disclosed in Japanese Patent Application No. 102800/1982 and Japanese Patent Application No. 3100/1981.
A corneal shape measuring device disclosed in No. 09 is known. The devices disclosed in these publications project a ring-shaped pattern (ring index light) onto the cornea of the eye to be examined through an objective lens directly facing the eye, and use the ring index image formed on the cornea as a light receiving section. The area CCD receives light, and the radius of curvature of the cornea is measured using the ring index image. In this way, conventionally, the measurement of the intraocular pressure of the eye to be examined and the measurement of the radius of curvature of the cornea were performed using a non-contact tonometer (also called a tonometer).
They are measured separately using separate devices called corneal topography and a corneal topography device (also called a keratometer). By the way, both tonometers and keratometers require alignment between the eye being examined and the device itself, and this alignment requires a great deal of time and skill. , the eye examination takes time, increasing the time burden for both the examiner and the examinee. In addition, in optical stores, eye hospitals, etc., tonometers and keratometers must be purchased separately and installed in examination rooms and optometry rooms, but this is not only a burden in terms of expenses, but also in terms of securing optometry space. It has become a burden. Therefore, with regard to the measurement of intraocular pressure and corneal shape, we developed an optical system for an ophthalmological instrument for both corneal shape measurement and intraocular pressure measurement, which can shorten eye examination time, reduce labor, save space, and reduce costs. An anterior segment II observation system for observing the anterior segment of the eye, which includes at least an objective lens that directly faces the optometrist and a light-receiving unit that forms an image of the anterior segment of the eye including the eye to be examined; established in
A ring index projection system that projects a ring index light to form a ring index image on the cornea of the eye to be examined; and an alignment index light whose optical axis obliquely intersects the optical axis of the objective lens. an alignment index projection system that projects onto the cornea to form a virtual image based on corneal specular reflection; and an optical axis that is symmetrical with the optical axis of the alignment index light projection system with respect to the optical axis of the objective lens. , another alignment index projection system that projects another alignment index light onto the anterior cornea to form another virtual image based on corneal specular reflection; a light receiving system that guides the fluid to the light receiving section; another light receiving system that guides the other image to the light receiving section via the first alignment index projection system; comprising a nozzle and a corneal applanation detection system that projects corneal applanation detection light for detecting corneal applanation based on fluid discharge and receives corneal applanation detection light based on corneal specular reflection;
A non-contact type intraocular pressure measuring means has been proposed which measures the intraocular pressure of the eye to be examined by deforming the cornea. (Problems to be Solved by the Invention) In the above configuration, it is desirable that both the ring index light and the alignment index light be infrared light so as not to dazzle the subject. However, in the above structure, if both the alignment index light and the ring index light are infrared light, the alignment index light is transmitted to the anterior eye through the objective lens based on the specular reflection of the cornea during alignment adjustment. The light enters the optical path of the partial observation system and reaches the area COD as the light receiving part, and ghosts and flares appear on the monitor screen based on the alignment index light that has entered through the objective lens, making it difficult to focus on the anterior segment. When adjusting the alignment by moving the main body of the device and confirming that the pair of alignment index images that appear as a light spot match, there is a problem in that it is difficult to see the pair of alignment index images on the monitor screen. Therefore, an object of the present invention is to avoid ghosts and flares that occur on the monitor screen based on the alignment index light that enters the optical path of the anterior segment observation system through the objective lens during alignment adjustment. Our objective is to provide an optical system for an ophthalmological instrument that can be used to measure corneal topography and intraocular pressure. (Means for Solving the Problems) In order to achieve the above object, an optical system of an ophthalmic instrument for both corneal shape and intraocular pressure measurement according to the present invention includes an objective lens directly facing the eye to be examined and the eye to be examined. an anterior segment observation system for observing the anterior segment of the eye, comprising at least a light receiving unit on which the anterior segment of the eye is imaged; a ring index projection system for projecting a ring index light to form a ring index; and a ring index projection system whose optical axis obliquely intersects with the optical axis of the objective lens, and projects one alignment index light onto the cornea of the eye to be examined to form a virtual image on the corneal mirror surface. one alignment index light projection system that is formed based on reflection; and an optical axis that is symmetrical to the optical axis of the one alignment index light projection system with respect to the optical axis of the objective lens, and the other seven alignment index lights are directed to the subject's eye. another alignment index projection system that projects the first virtual image onto the cornea to form another virtual image based on corneal specular reflection; and one light receiving system that guides the one virtual image to the light receiving section via the other alignment index projection system. and another light-receiving system that guides the other virtual image to the light-receiving unit via the first alignment index projection system, a nozzle that emits fluid toward the cornea, and a corneal applanation based on the fluid discharge. a corneal applanation detection system that projects corneal applanation detection light for detection and receives corneal applanation detection light based on corneal specular reflection;
a non-contact type intraocular pressure measuring means for measuring the intraocular pressure of the eye to be examined by deforming the cornea, the one alignment indicator light and the other alignment indicator light have the same wavelength, and the The ring index light is infrared light in a wavelength range different from that of the alignment index light, and the first alignment index light is also used as the corneal applanation detection light. (Function) According to the optical system of the ophthalmological instrument for both corneal shape measurement and intraocular pressure measurement according to the present invention, the infrared wavelength of the alignment index light and the infrared wavelength of the ring index light are made different, so alignment adjustment is possible. At this time, the alignment index light that enters the optical path of the anterior segment observation system via the objective lens can be cut using a wavelength selective optical element, etc. in the middle of the optical path of the anterior segment observation system, and therefore alignment adjustment At this time, it is possible to avoid ghosts and flares caused by the alignment index light on the monitor screen, making alignment adjustment easier. (Example) Hereinafter, an example of an optical system of an ophthalmological instrument for both corneal shape and intraocular pressure measurement according to the present invention will be described with reference to the drawings. FIG. 1 shows a perspective view of an optical system of an ophthalmological instrument for both corneal shape and intraocular pressure measurement according to the present invention, and this optical system includes an alignment optical system 1, an anterior segment observation system 2, a reticle optical system 3, and a ring index. It is roughly composed of projection system 4. The alignment optical system 1 includes a first optical system 5 and a second optical system 6.
It has The first optical system 5 has an LED 7 as a light source. The LED 7 emits infrared light with a wavelength of 880 nm, for example. The infrared light having a wavelength of 880 nm is focused by a condenser lens 8 and then passes through an aperture of an aperture 9 as an alignment index. The infrared light with a wavelength of 880nII1 is reflected by a half mirror 10 whose transmittance from visible to infrared is about 50%, and guided to a projection lens 11. The projection lens l1 has a focal point at the aperture position of the aperture 9. The infrared light of the LIID 7 is converted into a parallel light beam by the projection lens 11 and projected onto the cornea C of the eye to be examined as alignment index light. A virtual image is formed on the cornea C by reflection of the alignment index light on the cornea C. Here, the optical axes of the LED 7, condenser lens 8, half mirror IO, and projection lens 11 obliquely intersect with the optical axis of the anterior segment observation system, and one alignment index light is projected onto the cornea of the eye to be examined to form a virtual image. This constitutes an alignment index projection system that forms the image based on corneal specular reflection. The second optical system 6 includes a projection lens 12, a half mirror 13 with a transmittance of about 50% from visible to infrared, and a half mirror 14 with a transmittance similar to that of the half mirror 13.
, mirrors 15 and 16, and an imaging lens 17. The reflected light forming one virtual image is transmitted through the projection lens 12 of the second optical system 6.
After passing through the mirror and becoming a parallel beam of light, it passes through the half mirror 13 and the half mirror l4 and is guided to the imaging lens 17 between the mirrors 15 and 16, where one of the reflected beams forms one virtual image. A portion of the light is transmitted through a dichroic mirror 30 that partially reflects visible and infrared light and has transmittance characteristics to be described later, and the rest is reflected by the dichroic mirror 30. The reflected light forming the first virtual image is transmitted to the area COD 18 which constitutes a part of the front end observation system 2 by the imaging lens 17.
An alignment index image is formed on the light-receiving surface lea and an alignment sensor 32, which will be described later. Here, the projection lens 12, the half mirror 13, the half mirror 14,
The mirrors 15 and 16 and the imaging lens 17 constitute one light receiving system that guides one virtual image to the light receiving section via another alignment index projection system. Note that other alignment index projection systems will be described later. As shown in FIG. 2, the dichroic mirror 30 has flat transmittance characteristics from the visible wavelength range to the infrared wavelength range of approximately 780 nm, and its transmittance is approximately 70%. The transmittance of the dichroic mirror 30 decreases smoothly between the wavelength of approximately 800 nm and the wavelength of 860 na+, and again has flat transmittance characteristics in the infrared region of wavelength 860 n+s or more. Transmittance in the infrared region of 860 nm or more is approximately 1
It is 0%. Therefore, approximately 10% of the reflected light that forms one virtual image that is guided to the dichroic mirror 30 via another alignment index projection system is in the area COD1.
8, and the remaining 90% of the reflected light is reflected and guided to the alignment sensor 32.The second optical system 6 is provided with an LllD 19. The LED 19 emits infrared light having the same wavelength as the infrared light emitted from the LED 7. After the infrared light emitted from the r, ED 19 is condensed by a condenser lens 20,
The light passes through the aperture of the aperture 21 as an alignment index, is reflected by the half mirror 13, and is guided to the projection lens 12. The projection lens l2 has a focal point at the aperture position of the aperture 2l. The infrared light emitted from the LED 19 is the projection light. The light is projected as a parallel light beam by the lens 12, and another virtual image is formed on the cornea C of the eye to be examined. Here, L [
ID 19, condenser lens 20%, aperture 21, half mirror 13, and projection lens 12 have optical axes that are symmetrical to the optical axis of one alignment index projection system with respect to the optical axis of the objective lens, and direct the other alignment index light to the subject's eye. This constitutes another alignment index projection system that projects onto the cornea and forms another virtual image based on corneal specular reflection. The first optical system 5 includes a mirror 22. 23, an imaging lens 24 is provided, and the reflected light forming another virtual image is transmitted to the projection lens 1 of the first optical system 5.
1 to become a parallel light beam, and after passing through the half mirror 10, an imaging lens 24 between the mirrors 22 and 23
A part of the reflected light forming another virtual image passes through the dichroic mirror 30, and the rest is reflected by the dichroic mirror 30, and the imaging lens 24 connects the light receiving surface 18a of the area CCD 18 and the alignment sensor 32. It is then imaged as another alignment index image.
Here, the projection lens 1l, the half mirror 10, the mirror n
．． 23. The resultant lens 24 constitutes another light receiving system that guides another virtual image to the light receiving unit via the first alignment index projection system. The anterior segment observation system 2 includes a fluid discharge nozzle and an objective lens 26.
, a glass plate 27, a dichroic mirror that partially reflects visible and infrared rays as a wavelength selection optical element, an imaging lens 4,
The dichroic mirror 28 having the dichroic mirror 30 has wavelengths ranging from visible wavelengths to
It is manufactured so that the transmittance for infrared light of 80 nm is approximately 70%, and the transmittance for infrared light with a wavelength of 850 nm or more is approximately 0%. If the transmittance characteristics of the dichroic mirror 28 are designed as shown in FIG. 3, the wavelength that enters the optical path of the anterior segment observation system 2 through the objective lens 26 due to corneal specular reflection during alignment adjustment. Since the 880 nm infrared light is reflected by this dichroic mirror 28, it is possible to prevent the alignment index light from being guided to the area COD 18. Therefore, ghosts, flares, etc. will not appear on the monitor screen. When the intersection between the optical axes 01 and 02 of the first optical system 5 and the second optical system 6 and the optical axis On of the objective lens 2B of the fluid discharge nozzle 25 coincides with the vertex P of the cornea C, a virtual image is formed. and the other virtual images are located on the optical axes 0 and 02 and on the focal plane of the cornea C, and the one alignment index image and the other alignment index are located on the light receiving surface 18a of the area CCD 18. The images match, and at this time alignment between the regular reference working distance and the eye to be examined is obtained. The reticle optical system 3 generally consists of a light source, a reticle plate, and an imaging lens 35. The light source 33 emits infrared light having the same wavelength as the ring index light described later. Its predecessor 3
The infrared light emitted from the reticle plate 34 illuminates the reticle plate 34.
The illumination light that has passed through the reticle plate 34 is sent to the imaging lens 35.
is reflected by the dichroic mirror 30 and guided to the area CCD 18. This illumination light is imaged by the imaging lens 35 on the area COD 18 as a circular reticle image (not shown). The alignment optical system 1 here also serves as a corneal applanation detection system that projects corneal applanation detection light for detecting corneal applanation and receives corneal applanation detection light based on corneal reflection. To detect the applanation of the cornea, the LED 7 of the first optical system 5, the condenser lens 8, the aperture of the aperture 9, the half mirror 10, the projection lens 11, and the second
Projection lens l2 of optical system 6, half mirror 13, half mirror l4, imaging lens 36, diaphragm, applanation sensor 38
is used, and when an air pulse is emitted from the fluid ejection nozzle 25 to the cornea C to applanate the cornea C, the infrared light emitted from the projection lens 11 of the first optical system 5 is converted into a parallel beam by the applanation cornea. The projection lens 1 of the second optical system 6
2 and transmitted through the half mirror 13, guided to the half mirror 14, reflected by the half mirror 14, focused on the aperture of the diaphragm 37 by the imaging lens 36, and passed through the aperture. The light is imaged onto the applanation sensor 38. During corneal applanation, the light receiving beam of the applanation sensor 38 is at its maximum. The front end observation system 2 is provided with a ring index projection system 4. The ring index projection system 4 consists of a light source sphere, a condenser lens sum, and a pattern plate 42 on which an annular pattern 41 is formed. The light source 39 generates infrared light in a wavelength range different from the wavelength of the infrared light from the LEDs 7 and 19. Here, the wavelength of the infrared light emitted from this light source 39 is 7.
It is 80nm. The infrared light emitted from the light Pi 39 is condensed by a condenser lens 40 and illuminates an annular pattern 41. The infrared light that has passed through the annular pattern 41 is reflected by the dichroic mirror 28 as a ring index light, and then is reflected by the objective lens 26 at angle 1! ! It is projected towards the IC. The objective lens 26 is configured to image the annular pattern 4l at the position of the iris of the eye to be examined. The objective lens 26 and the imaging lens 29 also have the function of forming an image of the anterior segment of the subject's eye, including the iris, on the CCD 18 as an anterior segment image. , 4
It is illuminated by 3. The ring index light that has passed through the annular pattern 41 is projected so as to be focused on the center of curvature of the cornea C. The ring index light reflected by the corner IC passes through the objective lens 26 and the glass plate 27.
It is guided to the dichroic mirror 28 via. Since the dichroic mirror 28 has the transmittance characteristics shown in the second country, a part of the ring index light reflected by the cornea C is transmitted through the dichroic mirror 28 and is reflected by the imaging lens 29 onto the light receiving surface of the CCD 18. The image is formed on 18a. In addition, the objective lens 26 and the imaging lens 29#, the image of the annular pattern 41 formed at the position of the iris and the area CCD1
13 are arranged so that they are optically conjugate. By measuring the size of the ring index image projected on the area COD18, the radius of curvature of the cornea C can be measured. When the cornea C has astigmatism, the ring index image becomes an ellipse, so its major axis By measuring the major axis and the minor axis, it is possible to know the radius of curvature of the cornea C in both the strong and weak principal axes, and furthermore, the direction of the foraminal axis can be determined from the direction of the major axis or the minor axis. The fluid discharge nozzle 26 constitutes a part of an intraocular pressure measuring means that measures the intraocular pressure of the eye to be examined by discharging a fluid toward the cornea C and deforming the cornea. Here, the fluid discharge nozzle 25 passes through the center of the objective lens 26 and is attached to the objective lens 26. In addition, the intraocular pressure measurement means are as follows:
Although it is equipped with a fluid discharge system (not shown), its details are omitted. (Effect of IR light) Since the present invention is configured as described above, it is possible to cut out the alignment index light that enters the optical path of the anterior segment observation system during alignment adjustment. This has the effect of making it possible to avoid ghosts and flares caused by the alignment index light on the monitor screen, making alignment adjustment easier.
Furthermore, since the wavelength of one alignment index light and the wavelength of the other alignment index light are the same, it is possible to facilitate the production of the wavelength selection optical element.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the main structure of an optical system of an ophthalmological instrument for measuring corneal shape and intraocular pressure according to the present invention, and FIGS. 2 and 3 show the transmittance of the dichroic mirror shown in FIG. 1. This is a diagram showing the characteristics. l... Alignment optical system 5... First optical system, 6... Second optical system 2... Anterior segment observation system 4... Ring index image projection system 7... LED, 19. ...LED18...Area CCD (light receiving section) 28...Dichroic mirror (wavelength selection optical element)
30...Dichroic mirror 39...Light source 4l...Annular pattern

Claims (1)

[Scope of Claims] An anterior segment observation system for observing the anterior segment of the eye, which includes at least an objective lens that directly faces the eye to be examined, and a light receiving unit that forms an image of the anterior segment of the eye, including the eye to be examined; a ring index projection system that is provided in the anterior segment observation system and projects a ring index light to form a ring index image on the cornea of the eye to be examined; an alignment indicator projection system that projects an alignment indicator light onto the cornea of the eye to be examined to form a virtual image based on corneal specular reflection; and an optical axis of the alignment indicator projection system with respect to the optical axis of the objective lens. another alignment index projection system that has an optical axis symmetrical to the one and projects another alignment index light onto the cornea to form another virtual image based on corneal specular reflection; one light receiving system that guides the virtual image to the light receiving section via the projection system; another light receiving system that guides the other virtual image to the light receiving section via the one alignment index projection system; and a corneal applanation detection system that projects corneal applanation detection light for detecting corneal applanation based on fluid discharge and receives corneal applanation detection light based on corneal specular reflection. hand,
a non-contact type intraocular pressure measuring means for measuring the intraocular pressure of the eye to be examined by deforming the cornea, the one alignment indicator light and the other alignment indicator light have the same wavelength, and the The ring index light is infrared light in a wavelength range different from that of the alignment index light, and the first alignment index light is also used as the corneal applanation detection light. optical system of ophthalmological instruments.