JPS59230535A - 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 that can simultaneously measure the refractive power of the eye and the shape of the cornea using the same device.

Generally, when performing an eye refraction test, in addition to measuring refractive power, corneal shape measurements are also performed in parallel to test for the presence or absence of astigmatism, and to test the astigmatism axis and degree of astigmatism. In particular, with the spread of contact lenses in recent years, corneal shape testing has become more important in order to select the base curve of contact lenses.

Conventionally, when conducting such a test, the contact lens prescription first involves measuring the shape of the subject's cornea with an instrument called an ophthalmometer or keftometer, selecting a base curve and determining the amount of corneal astigmatism. It is common to screen for total refractive power and total astigmatism through an objective refraction test using a refractometer, etc., and then perform a subjective refraction test and final determination of the base curve using the trial lens method.

In this way, in the past, corneal shape measurement and refractive power measurement were performed separately using different types of instruments, and the time and effort required for measurement was a considerable burden on both the examiner and the examinee. It has become.

The purpose of the present invention is to improve such problems and to enable corneal shape and eye refractive power tests to be simultaneously measured using the same instrument, thereby significantly reducing measurement time and labor, as well as improving the test subject's eyeballs. The purpose of this device is to provide an ophthalmological measuring device that enables accurate measurement by correcting errors in the movement of the eye. An ophthalmological measurement device that optically detects an image and a corneal reflection image to measure eye refractive power and corneal shape,
The present invention is characterized in that a detection means for detecting a fundus reflection image and a detection means for detecting a corneal reflection image are provided separately.

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

FIG. 1 shows an optical system showing an embodiment of the present invention. During corneal shape measurement, visible light emitted from a ring-shaped strobe 1 is transmitted to a collimator ring lens 2 on the opposite side of the eye E.
It is designed to illuminate a circular slit 3 installed in the area. The slit 3 is located on the focal plane of the ring lens 2 when viewed in a cross section including the optical axis, and the slit 3 is optically located at an infinity point, so that the light projected from that infinity point is illuminated. The cornea Ec of the optometrist E is illuminated.

Since the surface of the eye E to be examined is like a convex mirror, a corneal reflection image Sa of the slit 3 is created, and this corneal reflection image Sa
passes through an objective lens 4, a visible light-transmitting/infrared-reflecting guichroic mirror 5, a half mirror 6, a multi-hole aperture 7, and is deflected by a prism 8 for one-dimensional position detection called COD. The image is re-imaged onto element 9.

As shown in FIG. 2(a), the multi-hole diaphragm 7 has, for example, five openings 7a to 7e, and the prism 8 also has openings 7a to 7e.
5 as divided by the dotted line in Fig. 2(a) corresponding to 7e.
elements 8a to 8e, each element 8
A to 8e have cross-sectional shapes as shown in (b).

5 separated by this multi-hole aperture 7 and prism 8.
The corneal reflection images are combined at the position of the detection element 9 in the relationship shown in FIG. In FIG. 3, sb represents a corneal reflection image formed by the corneal reflection image Sa formed and separated by the objective lens 4, and 9a to 9e are detection elements, respectively, including openings 7a to 7e, prism elements 8a to 8a. 8e. As a result, the corneal reflection image s
The coordinates of 5 points in b will be detected, and the coefficients A to E are obtained by substituting the coordinates of these 5 points into the general formula of the quadratic curve, AX2+BXY+CY2+Dx+EY+F=0 and solving the simultaneous equations. General formula of (x-Xo)2/a2+(y-yo)2/b2=square, X=Xcosθ-Y sinθy=Xsinθ+y
cos θ, the major axis a and the minor axis of the ellipse derive the radius of curvature of the bilateral meridian of the cornea Ec, and the astigmatic axis can be calculated from the angle O.

On the other hand, in the case of refractive power measurement, as shown in FIG.
The fundus projection chart 12 is illuminated through the fundus projection chart. As shown in FIG.
2a to 12c are provided. The light from the light emitting diode 10 further passes through the relay lens 13 and reaches the fundus illumination aperture 1.
4, the light passes through the perforated mirror 15 and the relay lens 16, is reflected by the guichroic mirror 5 because it is infrared light, and then passes through the objective lens 4 to the subject's eye E.
The image is formed on the pupil of the eye and illuminates the fundus of the eye.

Further, the chart 12 is once formed into an image through the relay lens 13.16, and is projected by the objective lens 4 so as to be conjugate with the emmetropic fundus. The reflected image from the fundus passes through the objective lens 4 again, is reflected by the guichroic mirror 5 to form an image, and further passes through the relay lens 16 to the perforated mirror 15.
reflected. An aperture plate 17 is located near the perforated mirror 15.
The aperture plate 17 has six openings 17a to 17f as shown in FIG. and opening 1
7a and 17d, 17b and 17e, and 17c and 17f respectively form one channel. The fundus illumination diaphragm 14 and the diaphragm plate 17 form images on the pupil of the eye E to be examined, as shown at 14A and 17A in FIG. 6, and separate the projection system and measurement system of the chart 12. .

The light beam divided by the diaphragm plate 17 passes through the imaging lens 18
The light is separated by a prism 19 via a cylindrical lens 20, focused in the transverse direction of the detection element 21, and imaged onto three detection elements 21a to 21c. The prism 19 has six elements 19a to 19f, as shown in FIG. Therefore, FIG. 7(b) shows the prism 19.
This figure shows the cross-sectional shape of .

The images separated in this manner are focused in the longitudinal direction of the images by three cylindrical lenses 20a to 20c, and are imaged onto detection elements 21a to 21c.

FIG. 8 shows the imaging state of the fundus image, and shows 22a to 22a.
22f represents a fundus image formed corresponding to the openings 17a to 17f.

If the eye E to be examined is an ametropic eye, the light ray that exits from the fundus and leaves the pupil is emitted at an angle that corresponds to the refractive power. The distance between the two fundus images 22 on the detection element 21 changes depending on the refractive power of the eye E to be examined.

Therefore, by determining the relationship between the distance between the two fundus images 22 and the refractive power in advance, the refractive power in the three radial directions can be measured, and each refractive power can be calculated using the following formula: D=A 5in2 ((1) 10 )+B to calculate the spherical power, astigmatic power, and astigmatic angle.

To align the eye E and the instrument, the anterior segment of the eye is transmitted through the guichroic mirror 5 using the objective lens 4, and the light beam reflected from the half mirror 6 is imaged onto the television image pickup tube 24 by the television relay lens 23. This can be done by a radio station or a separate television monitor.

Furthermore, in the embodiment, the guichroic mirror 5 has the characteristics shown in FIG. 9 that transmits visible light and reflects infrared light, and the light from the light emitting diode 10 that illuminates the fundus also emits infrared light. Since these wavelengths are used, the glare on the subject can be reduced, but these wavelengths can be arbitrarily selected without being limited to the embodiments.

As explained above, according to the ophthalmological measuring device according to the present invention, the fundus reflected light does not enter the corneal shape measuring means, and the corneal measuring light does not enter the refractive power measuring means.
Even if both light sources are turned on at the same time, a signal with a sufficient S/N ratio can be detected using each measurement method.
This means that measurements can be carried out simultaneously in a short time.

[Brief explanation of the drawing]

The drawing shows an embodiment of the ophthalmological measuring device according to the present invention,
FIG. 1 is a diagram of its optical configuration, FIG. 2(a) is a front view of a multi-hole diaphragm, FIG. 2(b) is a cross-sectional view of a prism, and FIG. 3 is an explanatory diagram of the relationship between a corneal reflection image and a detection element. FIG. 4 is a front view of the fundus projection chart, FIG. 5 is a front view of the aperture plate for eye refraction measurement, and FIG. 6 is a front view of the image formation state of the aperture on the pupil of the eye to be examined.
FIG. 7(a) is a front view of an image separation prism for eye refraction measurement;
(b) is a sectional view thereof, FIG. 8 is an explanatory diagram of the relationship between the fundus image and the light receiving element, and FIG. 9 is a characteristic diagram of the guichroic mirror. Symbol l is a ring-shaped strobe, 2 is a ring lens, 3 is a slit, 4 is an objective lens, 5 is a gicroic mirror,
6 is a half mirror, 17 is a multi-hole diaphragm, 8.19 is a prism, 9.21 is a detection element, 10 is a light emitting diode, 12
is a chart, 14 is an illumination diaphragm, 15 is a perforated mirror, 1
7 is an aperture plate, 20 is a cylindrical lens, and 24 is a television image pickup tube. Patent applicant Canon Corporation 11%3 Figure 5 Figure 7 Figure 7 m8 Figure 185-

Claims (1)

[Claims] (1) Ophthalmology in which light of a predetermined shape is projected onto the fundus and cornea of the eye to be examined, and the fundus reflected image and corneal reflected image are optically detected to measure eye refractive power and corneal shape. A measuring device for ophthalmology, characterized in that a detecting means for detecting a fundus reflected image and a detecting means for detecting a corneal reflected image are provided separately. 2. The light projected onto the fundus is 3. In the detection means for projecting through a slit in the meridian direction and detecting the reflected image, the detection element is arranged in a one-dimensional position corresponding to at least three meridian directions.Claim 1 The ophthalmological measuring device described in . 3. In the detection means for detecting the corneal reflection image,
The ophthalmological measurement device according to claim 1, wherein the detection element is a one-dimensional position detection element arranged corresponding to the position coordinates of at least five points of the corneal reflection image. 4. The optical path for projecting the corneal reflection image and the optical path for projecting the fundus reflex image share a part of the optical path, and the reflected light is divided into two detection means by an optical path dividing member. The ophthalmological measuring device according to item 1. 5. The ophthalmological measuring device according to claim 4, wherein the eye refractive power measuring light and the corneal shape measuring light have different wavelengths. 6. The ophthalmological measuring device according to claim 5, wherein the optical path dividing member is a dichroic mirror. 7. The ophthalmological measuring device according to claim 5, wherein the eye refractive power measuring light is infrared light and the corneal shape measuring light is visible light.