JPS6021738A - Ophthalmic measuring apparatus - 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 The present invention relates to an ophthalmological measuring device for measuring the refractive power and corneal curvature of the eye.

Conventionally, various types of ocular refractometers that can automatically measure the refractive power of the eye have been known, and keratometers have ranged from manual types such as keratometers to those that can recently measure automatically. Various formats have been developed.

Furthermore, a combination of these two types of measuring devices is also disclosed, for example, in Japanese Patent Application Laid-Open No. 58-29446.
This method has the disadvantage that the chart for eye refractive power measurement and the chart for corneal measurement are placed in completely separate positions, which increases the number of optical members for each projection, complicating the entire optical system. There is. Another drawback is that the optical system that projects the chart onto the fundus of the eye and the optical system that projects the chart onto the cornea are completely independent, so adjustment of these two optical paths must be done separately. There is.

An object of the present invention is to reduce the number of optical members by making it possible to share a part of the optical path of the projection optical system for eye refractive power measurement and the projection optical system for keratometry, in order to improve such drawbacks. The object of the present invention is to provide an ophthalmological measuring device in which the configuration of the optical system and its adjustment are simplified, and the gist thereof is to provide two projection means for respectively projecting predetermined charts onto the fundus and cornea of the eye to be examined; and a detection means for respectively detecting a fundus reflection image and a corneal reflection image of each chart, and calculating the ocular refractive power from the fundus reflection image and the curvature of the angle 11 from the corneal reflection image, the measuring device comprising: It is characterized in that both throwing means share a part.

The present invention will be explained in detail below based on illustrated embodiments.

FIG. 1 shows an embodiment of the present invention, in which E represents the eye to be examined, E and f represent the fundus, Ec represents the cornea, and Ep represents the pupil. In FIG. 1, a fundus projection chart 1 is illuminated with light from a light emitting element 2 that emits near-infrared light through a condenser lens 3, a relay lens 4, a circular aperture 5,
The image is once formed on the image plane F through the perforated mirror 6, and further transmitted through the tichroic mirror 7 in the left row 17, and is imaged on the fundus Ef by the objective lens 8. The reflected image reflected by the fundus Ef travels to the right, passes through the objective lens 8 and the gyroic mirror 7, forms an image on the -result image plane F, is reflected by the perforated mirror 6, and then passes through the aperture 9 and the relay lens 10.
The light is deflected by a prism 11 through a reflecting mirror 12 and a cylindrical lens 13, and is imaged onto a one-dimensional photodiode array (hereinafter referred to as CCD) 14, which is a detection means. Cylindrical lens 13
An image of the aperture 9 is formed on the CCD 14 in a direction having an initial deflection force. Further, the tichroic mirror 7 used has a characteristic of transmitting near-infrared light from the light emitting element 2 and reflecting visible light.

On the other hand, a chart 21 for corneal projection is illuminated by an illumination bulb 22 that emits visible light, which passes through a relay lens 23 and a half mirror 24, is reflected by a dichroic mirror 7 via a relay lens 25, and travels to the left. , are projected onto the angle IQEc by the objective lens 8. And corner) Char 1 and 2 reflected by model Ec
The corneal reflection image of No. 1 moves to the right, passes through the objective lens 8 again, is reflected by the microink mirror 7, and is reflected by the field lens 25.
After passing through the half mirror 24, the relay lens 2
6 and the aperture 27, and is deflected by the prism 28.
It is configured to be imaged onto D29.

As shown in Fig. 2, the chart 1 for fundus projection has three tree picks, y-tl a-1c, which are oriented radially at an angle of 120 degrees to each other in the so-called three meridian directions, and their images are projected onto the fundus. The image is focused on Ef. In this case, the circular aperture 5 forms an image in the vicinity of the pupil EP, resulting in a so-called macroscopic view in which the entrance pupil diameter is artificially determined. The light reflected by the fundus Ef is extracted again from the pupil El), but the pupil E
p is approximately conjugate with the aperture 9 shown in FIG. 3, and an image P5 of the aperture 5 and an image P9 of the aperture 9 are formed on the pupil EP as shown in FIG.

The aperture 9 has six 13M openings 9a to 9f as shown in FIG.
%, and the 51st threshold (
6 wedge-shaped prism elements 1 as shown in b)
It is constructed by la-11f. The co-images j by the openings 9a to 9f of the S intersection 9 are 15 pairs l and N to the nosm elements lla to llf, respectively. It also consists of three lenses 13a to 13C arranged in the direction of the meridian line 13ii3, and the CCD
The lens 14 is also composed of three elements 14a to 14c), and the lenses 13a to 13c and the elements 14a to 14c are one
Each item is addressed individually.

The fundus reflected image by the slit image of the fundus projection chart 1.1 is formed before and after the -component image plane F and enters the diaphragm 9. In this case, the co-image formed by the apertures 9a to 9f of the diaphragm 9 is divided by each element 11a to llf of the prism 11. As shown in FIG. 6, the relationship between the CCD 14 and the reflected images is that the fundus reflected images Ra-Rf of the chart 1 formed by the openings 9a-9f of the aperture 9 are
4c'2. And aperture 9
The six openings are 9a and 9b, 9C and 9d, 9e and 9f.
form pairs, and each pair corresponds to three elements 14a-14c. Therefore, reflected images Ra and Rb are on element 14a, Re and Rd are on element 14b, and Re and Rf are on element 14c.
The image will be formed. On the other hand, cylindrical lens 1
3a to 13c are openings 9a in the direction of having refractive power.
9f on the elements 14a to 14c, and has the role of reducing the image in the lateral direction and increasing the amount of light. Therefore, by measuring the distance between the peaks of the outputs of the elements 14a'-14c, the refractive power in each meridian direction corresponding to the elements 14a-14c can be determined.

slit) lal-1'c in chart 1 is 12.0 to each other
From the refractive power corresponding to each angle θ, Dθ=A+B(, e 5in(θ+Oo ) ・”(1
) holds true. Note that A is the value related to the spherical power Sph, Bo is the value related to the astigmatic power cy+, and C0 is the astigmatic axis A.
It is a value related to I. Therefore, sph, cy+, A
In order to calculate x, it is sufficient to calculate the refractive power in at least three meridian directions.

Further, the curvature of the cornea Ec can be measured according to the principle described below. The corneal projection charts 1 and 21 are annular slits 1-21, as shown in FIG. a, and the eye to be examined E
The objective lens 8 illuminates the cornea Ec with a parallel beam of light. Since the angle II'2Ec is considered to be a convex mirror, a virtual image (■) of Char 1.21 will be created behind it. As shown in FIG. 8, the diaphragm 27 has, for example, five circular openings 27a to 27e, and is similarly arranged at a substantially infinity point of the eye E to be examined. Also, prism 2
As shown in FIG. 9(a), which is a front view, and FIG. 9(b), which is a side view, openings 27a to 27e of the diaphragm 27.
It consists of five wedge-shaped prism elements 28a to 28e, respectively corresponding to the above. In addition, C0D28 also has openings 27a to 27e, prism niremen) 28a to 28
It consists of five elements 28a to 28e corresponding to e, and are arranged in the five meridian directions, that is, in directions shifted by 72 degrees from each other. Then, virtual images 5a-3e as shown in FIG. 1O are formed on these elements 29a-29e.

In general, the human cornea Ec can be considered to have a toric surface, so the corneal reflection image 5 of the annular chart 21
a-9e becomes an ellipse. Therefore, when the position of the image 5aNSe is detected by the signals from the elements 29a to 29e,
General formula for quadratic curve, AX2+BX+CXY +DY+EY2 +F=0...Substitute into (2) and (
Transform the formula 1) into the following general formula for the ellipse in formula (3): x2/a2+Y2/b2=1...(3),
The angle θ formed by the major axis a, the minor axis, and the long sleeve direction of the ellipse can be calculated. On the other hand, as described above, the chart 21 illuminates the cornea Ec from an infinite distance, and the aperture 27 is also placed at an infinite distance, so the light rays near the cornea Ec become as shown in FIG. 11, and the image height is From the radius of curvature r of Ec and the angle θ of the incident ray, r=h/5in(θ/2>−(4)), and the corneal curvature r can be calculated based on this equation (4).

FIG. 12 shows another embodiment of the present invention, and shows the first embodiment.
The same reference numerals as in the figures indicate the same members. In this embodiment, the glaucroic mirror 7 of FIG. 1 is replaced by a mechanically actuated flip-up mirror 30. Part of the optical path can be switched such that eye refractive power is measured by retracting the flip-up mirror 30 from the optical path, and corneal curvature measurement is performed by entering the flip-up mirror 30 into the optical path.

In the embodiment shown in FIG. 1, since the types of light sources are different and wavelengths can be separated by the guichroic mirror 7, refractive power measurement and corneal curvature measurement can be performed simultaneously. However, since the embodiment shown in FIG. 12 uses a flip-up mirror 30, both measurements cannot be performed at the same time, but the light sources may be of the same type.

As explained above, the ophthalmological measuring device according to the present invention includes:
Because some parts, mainly the objective lens, in the optical system that projects charts for measuring eye refractive power and corneal curvature can be shared, the number of optical system parts can be reduced, making it possible to reduce the number of optical system parts required for conventional, complex optical systems. This has the effect of simplifying the configuration and adjustment thereof.

[Brief explanation of drawings]

The drawings show an embodiment of the ophthalmological measurement device according to the present invention, in which FIG. 1 is a diagram of its optical configuration, FIG. 2 is a front view of a chart for projecting the fundus, and FIG. 3 is a diagram of an aperture for extracting light reflected from the fundus. The front view, Figure 4 is a diagram of the pupil of the subject's eye divided by the aperture, and Figure 5 (
a) is an explanatory diagram of the positional relationship with the front of the prism, FIG. 7 is a front view of the corneal projection chart 1, FIG. 8 is a front view of the aperture for extracting corneal reflected light, and FIG. 9 (a) is The front view of the prism, (b) its side view, and Fig. 10 the corneal reflection image and C.
FIG. 11 is an explanatory diagram of the positional relationship of the CU, FIG. 11 is an explanatory diagram of corneal curvature calculation, and FIG. 812 is an optical configuration diagram of another embodiment. Symbol l is a yard for fundus projection, 2 is a light emitting element, 5 is an aperture, 6 is a perforated mirror, 7 is a gyroic mirror, 8 is an objective lens, 9 is an aperture, 11 is a prism, 13 is a cylindrical lens, 14 is a CCD, 21 is a corneal projection chart 1, 22 is an illumination light source, 24 is a half mirror, 127 is an aperture, 28 is a prism, 29 is a COD, 3o is a flip-up mirror, E is an eye to be examined, Ef is a fundus, and Ec is a Ep is the cornea, Ep is the pupil, F is the primary imaging plane, and ■ is the virtual image. Patent applicant Canon Co., Ltd.

Claims (1)

[Scope of Claims] Two projection means for projecting predetermined charts onto the fundus and cornea of the eye to be examined, and a detection means for detecting a fundus reflection image and a corneal reflection image of each of the charts, 1. A measuring device for ophthalmology that measures eye refractive power from a reflected image and corneal curvature from the corneal reflected image, wherein both of the projection means share a part thereof. 2. As the means for detecting the fundus irregular image, at least 3
The ophthalmological measuring device according to claim 1, which uses three photodiode arrays arranged corresponding to the meridian direction. 3. As the corneal reflection image detection means, at least 5
The ophthalmological measuring device according to claim 1, which uses five photodiode arrays arranged corresponding to the meridian direction. 4. The ophthalmological measuring device according to claim 1, wherein the chart projection means has one stage of switching element for switching a part of the optical path when measuring eye refractive power and when measuring corneal curvature. 5. The ophthalmological measuring device according to claim 4, wherein the switching means uses different wavelengths of light sources to be used and selects the wavelengths. 6. The ophthalmologic measuring device according to claim 4, wherein the switching means is operated by a flip-up mirror.