JPS61185242A - 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 [Field of Application of Industry-L] The present invention relates to an ophthalmological measuring device for measuring eye refractive power and corneal shape, which has a fixation target that can be controlled to suit each measurement. It is something.

[Prior Art] Generally, when performing an eye refraction test, in addition to measuring refractive power, the corneal shape is also measured in order to test for the presence of astigmatism and to test the astigmatism axis and degree of astigmatism. . Conventionally, when conducting such tests, corneal shape measurement and refractive power measurement were performed separately using different instruments, but the time and number of L required for measurement were Since it is a considerable burden on both sides, in recent years, devices that can perform both measurements have been manufactured using rotary instruments.

By the way, generally when measuring eye refractive power or corneal shape, the subject's eye is fixed on a fixation target provided inside the device, and then a predetermined target is placed on the fundus or cornea of the subject's eye. is projected, the reflected image is received by a detector, and measured values are obtained by analyzing them.

There are two types of fixation target for measuring eye refractive power: a slide photograph of a landscape, etc., and a radial pattern.The latter radial pattern is designed to direct the eye to its center. In devices that measure eye refractive power and corneal shape using the same instrument, one of these fixation targets is installed; Since the measurement results are greatly affected by the examiner's movement, it is necessary to make the examinee's eye gaze at the optotype more firmly and to fix the examinee's eye more reliably. Therefore, if the fixation target for eye refractive power measurement is used as it is when measuring the corneal shape, accurate measurement may be hindered.

When using a slide such as a corneal slide as a common fixation target, the subject gets confused as to where to look on the slide, making it difficult to fix the subject's eye, making it unsuitable as a fixation target for corneal topography measurement. It is. In addition, when a radial pattern is used as a common fixation target, the center of the pattern is fixed at the position of emmetropia, so in the case of subjects with moderate or severe myopia/hyperopia, the pattern may be distorted. Is the subject's eye fixed because it is blurry and unable to gaze? This is also insufficient as a fixation target for corneal topography measurement. As described above, the conventional fixation targets are not fully satisfactory, which causes a decrease in measurement accuracy.

[Object of the Invention] The object of the present invention is to significantly reduce measurement time and labor by providing a fixation target that can be controlled to be suitable for measuring both eye refractive power and corneal shape. It is an object of the present invention to provide an ophthalmological measuring device which enables highly accurate measurement by being fixed to

[Summary of the Invention] - The gist of the present invention for achieving the object mentioned in F is to provide an optical system for measuring the eye refractive power of an eye to be examined, and a corneal shape that partially shares the optical system with the optical system for measuring the eye refractive power. and a fixation means for measuring eye refractive power.

This is an ophthalmological measurement device characterized by having a fixation means for corneal shape measurement, and a control means for separately presenting both of the fixation means to the eye to be examined so as to be suitable for each measurement.

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

FIG. 1 shows an optical system showing an embodiment of the present invention, in which visible light emitted from a ring-shaped strobe 1 is directed to a collimator ring lens 2 facing the subject's eye E during corneal shape measurement.
A circular slit 3 provided in the slit 3 is illuminated. 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 of the slit 3 is created, and this corneal reflection image reflects only the near-infrared light through the objective lens 4 and rejects light of other wavelengths. It passes through the visible light reflecting mirror 5, is reflected upward by the visible light reflecting kaiseki outdoor light transmitting visible light mirror 6, is reflected to the right by the beam splitter 7, and is transmitted to the multi-hole diaphragm 8.
The light is deflected by a prism 9 and reimaged onto a one-dimensional position detection element 10 consisting of a CCU (charge coupled device).

As shown in FIG. 2(a), the multi-hole diaphragm 8 has, for example, five apertures 8a to 8e, and the prism 9 also has an aperture 8a.
It has five elements 9a to 9e as divided by dotted lines corresponding to elements 9a to 8e, and each of these elements 9a to 9e
has a cross-sectional shape as shown in FIG. 2(b). The five corneal reflection images separated by the multi-hole aperture 8 and the prism 9 are combined at the position of the detection element 10 in the relationship shown in FIG. In FIG. 3, sb represents a corneal reflected image obtained by forming and separating an image reflected by the cornea Ec by the objective lens 4, and 10a to 10e are detection elements, respectively, and apertures 8a to 8e, a prism Niremen)
9a to 9e, respectively. by this,
The coordinates of 5 points in the corneal reflection image Sb are detected, and the coordinates of these 5 points are expressed by the general formula of a quadratic curve, AX2 +BXY+CY2 +DX+EY+F= 0
Find the coefficients A to E by substituting them into the equations and solving the simultaneous equations to obtain the general formula for the ellipse.

(X-XO)2/a2+(y-yO)2/b2=However, 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 bibionic meridian of the cornea Ec, and the astigmatic axis can be calculated from the angle θ.

On the other hand, in the case of refractive power measurement, as shown in FIG.
2 to illuminate the fundus projection chart 13. This chart 13 includes three slots in the three meridian directions that make an angle of 120 degrees to the phase q-, as shown in Figure 4.
13a to 13c are provided. The light from the light emitting diode 11 further passes through the relay lens 14 and forms an image on the fundus illumination diaphragm 15, and then passes through the perforated mirror 16, which is infrared light, and then passes through the dichroic mirror 6, where it is infrared light. Only external light passes through the dichroic mirror 5 and is imaged on the pupil of the eye E to be examined via the objective lens 4, thereby illuminating the fundus Ef.

The image of the chart 13 created by this far infrared light is the relay lens 1
4 and is once formed into an image, and projected by the objective lens 4 so as to be conjugate with the fundus of the stationary eye.

The reflected image from the fundus Ef passes through the objective lens 4 again, passes through the dichroic mirror 5.6, forms an image, and is reflected downward by the perforated mirror 16. A diaphragm plate 17 is disposed near the perforated mirror 16, and this diaphragm plate 17 has six apertures 17a to 17f each consisting of an annular transmitting portion, as shown in FIG. The openings 19a and 19d, 19b and 19e, and 19c and 19f correspond to each other and form one channel. The fundus illumination diaphragm 15 and the diaphragm plate 17 form images on the pupil of the subject's eye E as shown at 15A and 17A in FIG. It looks like this.

The light beam divided by the diaphragm plate 17 passes through the imaging lens 18 and is separated by the prism 19, and is then separated by the reflecting mirror 20.
The light is focused in the lateral direction of the detection element 22 through the cylindrical lens 21, and is imaged on three detection elements 22a to 22cl. The prism 19 is shown in FIG.
), it has six elements 19a-19f, and is designed to separate images corresponding to the six openings 17a-17f of the aperture plate 17, as shown in FIG. 7(b). shows the cross-sectional shape of the prism 19.

The thus separated images are focused in the longitudinal direction of the images by three cylindrical lenses 21a to 21c arranged as shown in FIG.
A fundus image P corresponding to the openings 17a to 17f
a-Pf.

If the eye E to be examined is an ametropic eye, the light ray that exits from the fundus Ef and exits at a point above the pupil will be emitted at an angle that corresponds to the refractive power, so an optical system like the one in this example is used. Then, the distance between the two fundus images P at the detection element 221- changes according to the refractive power of the eye E to be examined.

Therefore, if the relationship between the distance between the two fundus images P and the refractive power is determined in advance, the refractive power in the three radial directions can be measured, and each of the refractive powers is substituted into the following formula, D=A sin (2ω + θ) + B. The spherical power, astigmatic power, and astigmatic angle can be calculated using The variables D and ω represent the refractive power and the radial angle, respectively, and the constants A, B, and θ correspond to the degree of astigmatism, the average refractive power, and the astigmatic axis, respectively.

The alignment between the eye E and the instrument is achieved by emitting light from a light source (not shown) and using a guichroic mirror 5 using an objective lens 4.
The infrared light reflected downward from the anterior segment of the eye is imaged onto a television image pickup tube 24 by a television relay lens 23, and the image can be imaged by a television monitor attached to the main body or provided separately.

The eye refractive power measurement fixation target 25 is provided above the beam splitter 7 together with a light source 26, and the fixation target 25 illuminated by the light source 26 is gazed by the eye E through the relay lens 27 and the beam splitter 7. It has become so. The fixation target 25 is controlled to remove the mechanical myopia of the eye E by moving the optical axis downward together with the light source 26 and fixing the eye E in a fixed position for measurement. .

When a slide such as a landscape is used as the fixation target 25,
Since it is inappropriate to use this as a fixation tank for corneal shape M4, another fixation target is provided at the emmetropic eye position of [1111KEf] of the eye E to be examined.For example, in this example,
One end of the fiber 28 is arranged at the center of the prism 9, and a light emitting diode 29 that emits visible light is arranged near the other end. Then, during corneal shape measurement, the illumination light source 26 is turned off, the light emitting diode 29 is turned on, and the light emitting diode 29 emits light through the fiber 28 at the center of the prism 9, so that the subject 1111E gazes at a clear -4. Therefore, the eye E to be examined is fixed.

FIG. 9 shows a second embodiment in which the fiber 28 is installed at another emmetropic eye position of the subject WE, in which the fiber 28 is installed at the center position on the illumination light source 26 side of the fixation target 25 for eye refractive power measurement. One end is installed, and a light emitting diode 29 is placed at the other end. In this embodiment as well, the corneal shape is measured following the same procedure as in the previous embodiment, but in the case of this second embodiment, the fiber 28 can also be moved together with the fixation target 25, so the corneal shape can be measured. The subject's eye E can be made to gaze at a particularly clear bright spot.

If a radial pattern is used as the fixation target 25 for refractive power measurement, it can also be used for corneal shape measurement, but since the fixation target 25 is usually installed at the emmetropic position, Only the eye to be examined can be gazed at. Therefore, in order to set the fixation target 25 at a position corresponding to the refractive power of the eye E, it is preferable to simply measure the refractive power before measuring the corneal shape.
By emitting light twice, detecting the reflected image from the fundus Ef with the detection element 22, and moving the fixation target 25 to a position according to its refractive power, the fixation target 25 becomes clearly visible to the subject. , the eye E to be examined can be reliably fixed. In addition, fixation target 2
Since the value of the spherical power necessary for determining the position of 5 may be a rough number, only the l radius may be processed to shorten the measurement processing time.

If only corneal topography is to be measured, perform a simple refractive power measurement like this, but if refractive power and corneal topography measurements are to be performed consecutively, the measurement results of the refractive power measurement can be used as is. can do. That is, it is sufficient to move the fixation target 25 to a position corresponding to the spherical power obtained by the refractive power measurement and then proceed to the corneal shape measurement.

FIG. 1O shows the control circuit of this device, which includes a corneal shape measuring circuit 30 that inputs the signal of the detection element 1O, an eye refractive power measurement circuit 31 that inputs the signal of the detection element 22, and a signal of the eye refractive power measurement circuit 31. Input and integrated fixation target 25 and light source 2
A fixation target control circuit 32 that controls the fixation target 6, and a fixation target illumination control circuit 33 that controls the light source 26 and the light emitting diode 29, perform selection of measurements, procedures during continuous measurement, and control of the fixation target 25 and lighting device. Each is connected to a measurement selection control circuit 34.

Note that the fixation target illumination control circuit 33 is a measurement selection control circuit 34.
This circuit is for appropriately switching the lighting of the light source 26 and the light emitting diode 29 according to the command, so this control circuit 33 is omitted when the fixation target 25 is one that allows the focus to be focused on the center of a radial pattern or the like. can.

In a device in which a fiber 28 is provided because a slide such as a landscape is used as the fixation target 25, the measurement selection control circuit 34
When eye refractive power measurement or continuous measurement is selected, the light source 26 is turned on by the fixation target illumination control circuit 33, and while the fixation target control circuit 32 moves the fixation target 25 and the light source 26, the detection element 22 By inputting the signal to the eye refractive power measurement circuit 31, it is possible to obtain accurate refractive power measurement results in which instrumental myopia has been removed.

In the case of continuous measurement, the light source 2 is controlled by the fixation target illumination control circuit 33.
6 is turned off and the light emitting diode 29 is turned on to create a bright spot on the fiber 28 that can be easily observed by the eye E to be examined, the eye E to be examined is fixed and the measurement is performed, and the signal from the detection element 10 is sent to the corneal shape measuring circuit 30. The corneal topography measurement results can be obtained using the following method. When corneal shape measurement is selected by the measurement selection control circuit 34, the light emitting diode 29 is turned on by the fixation target illumination control circuit 33, and the corneal shape measurement value is obtained by following the same procedure as described above.

When a radial pattern is used as the fixation target 25, if eye refractive power measurement or continuous measurement is selected by the measurement selection control circuit 34, eye refractive power measurement is performed in the same manner as before, and continuous measurement is selected. When the fixation target control circuit 32 fixes the fixation target 4! I25 is moved to the position obtained by the eye refractive power measurement, the fixation target 25 is made to gaze at the eye E, and the corneal shape is measured.

When only corneal shape measurement is selected by the measurement selection control circuit 34, data in only one radial direction is inputted from the detection element 22 to the eye refractive power measurement circuit 31 according to the procedure for eye refractive power measurement, and the result is fixed. The fixation target 25 is moved by the target control circuit 32, and the eye E to be examined is made to gaze at the fixation target 25 to perform normal corneal shape measurement.

[Effects of the Invention] As explained above, according to the ophthalmological measuring device according to the present invention, fixation targets suitable for eye refractive power measurement and corneal shape measurement are provided, and these are switched and presented at the time of measurement, Alternatively, when measuring the corneal shape using the same fixation target, by moving the fixation target to a position suitable for the eye to be examined obtained by eye refractive power measurement, the fixation target can be presented to the eye to be examined clearly and the measurement can be performed. It is possible to shorten the alignment time and obtain accurate measurement results.

[Brief explanation of the drawing]

The drawings show an embodiment of the ophthalmological measuring device according to the present invention, in which FIG. 1 is an optical configuration diagram thereof, FIG. 2(a) is a front view of a multi-hole aperture, and FIG. 2(b) is a sectional view of a prism. Figure 3 is an explanatory diagram of the relationship between the corneal reflection image and the detection element.
The figure is a front view of the fundus projection chart, Figure 5 is a front view of the aperture plate for eye refraction measurement, Figure 6 is a front view of the image formation state of the aperture on the pupil of the eye to be examined, and Figure 7 (a) is the eye. A front view of the image separation prism for 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 another embodiment of the fixation target for corneal shape measurement. FIG. 1O is a block circuit diagram of the control circuit. 1 is a ring-shaped strobe, 2 is a ring lens, 3 is a slit, 4 is an objective lens, 5.6 is a gicroic mirror, 7 is a beam splitter, 8 is a multi-hole aperture, 9.19
is a prism, 10.22 is a detection element, 11.29 is a light emitting diode, 13 is a chart, 15 is an illumination diaphragm, 16 is a perforated mirror, 17 is a diaphragm plate, 21 is a cylindrical lens, 24 is a television image pickup tube, 25 is a A fixation target, 26 a light source, 28 a fiber, 30 a corneal shape measurement circuit, 31 an eye refractive power measurement circuit, 32 a fixation target control circuit, 33 a fixation target illumination control circuit, and 34 a measurement selection control circuit. It is.

Claims (1)

[Claims] 1. An optical system for measuring the eye refractive power of an eye to be examined, comprising an optical system for measuring the eye refractive power and a corneal shape measuring optical system partially sharing the optical system with the optical system for measuring the eye refractive power. An ophthalmological measuring device comprising: a fixation means, a fixation means for corneal shape measurement, and a control means for separately presenting both of the fixation means to the eye to be examined so as to be suitable for each measurement. 2. The fixation means for measuring the eye refractive power is a slide of scenery, etc., and the fixation means for measuring the corneal shape is a point light source installed at the position of the emmetropic eye. Ophthalmological measuring device. 3. Ophthalmological measurement according to claim 1, wherein the fixation means for measuring the eye refractive power has a radial pattern, and the fixation means for measuring the corneal shape is a point light source installed at the position of the emmetropic eye. Device. 4. The fixation means for measuring the eye refractive power and the fixation means for measuring the corneal shape have a common radial pattern, and the fixation means for measuring the corneal shape is moved to a position corresponding to the refractive power of the eye to be examined. An ophthalmological measuring device according to claim 1, wherein the ophthalmological measuring device is configured as follows. 5. The ophthalmological measurement according to claim 1, wherein the control means includes a control circuit that switches between the fixation means for measuring the eye refractive power and the fixation means for measuring the corneal shape for each measurement. Device. 6. During continuous measurement of refractive power and corneal shape, the control means:
Claim 4, further comprising a control circuit so as to perform corneal shape measurement by moving the fixation means for eye refractive power measurement to a position corresponding to the refractive power of the eye to be examined obtained by refractive power measurement.
The ophthalmological measuring device described in section. 7. When measuring the corneal shape alone, the control means measures the refractive power of the eye to be examined over one radial line, and moves the fixation means for measuring the eye refractive power to a position corresponding to the refractive power of the eye to be examined obtained as a result. 7. The ophthalmological measuring device according to claim 6, further comprising a control circuit for controlling the corneal shape measurement.