JPS6257534A - 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 [Industrial Field of Application] The present invention provides an ophthalmological JILT that allows the refractive power and corneal shape of an eye to be examined to be continuously determined with the same device.
This relates to fixed equipment.

[Prior Art] Generally, when testing the refractive power of the eye, it is necessary to measure the corneal shape to test for astigmatism in parallel with the eye refractive power measurement. It is becoming increasingly important to carry out measurements in parallel.

Conventionally, eye refractive power has been measured separately using an automatic refractive power measuring device called Autoref, and corneal shape measurement has been carried out using an automatic corneal shape measuring device called Autokent. When measuring eye refractive power with an auto reflex camera, the accommodative effect works on the eye being examined, so it is approximately 3 to 5 for each eye.
Measurements are taken several times, and the measurement results are obtained by averaging processing to select stable values from the results. Also, in the case of corneal topography measurement, the angular shape is relatively stable, but? When determining M, the measurement accuracy is more sensitive to alignment accuracy and eye movement than when measuring eye refractive power, so it is necessary to measure 3 to 5 times and find the average value, just like with an auto reflex camera. method is adopted.

In this way, in the conventional case, eye refractive power Jll determination and corneal shape measurement are each performed using separate devices, each measurement is repeated about 3 to 5 times, and averaging is performed to select stable data from among them. Since processing etc. are being carried out, 1. It takes a lot of time to measure each subject and organize the obtained measurement values, which is a considerable burden on both the subject and the examiner.

[Object of the Invention] In order to improve the above-mentioned conventional drawbacks, the object of the present invention is to measure eye refractive power and corneal shape continuously and multiple times in one measurement operation using the same device. To provide an ophthalmological measuring device capable of performing examinations at high speed and efficiently by obtaining stable data by storing the measured data and automatically performing averaging processing.

[Summary of the Invention] The gist of the present invention for achieving the above-mentioned object is an ophthalmological measuring device having an eye refractive power measuring optical system and a corneal shape measuring optical system that partially share an optical system, an input means for inputting and setting the number of measurements for eye refractive power measurement and the number of measurements for corneal shape measurement; a first storage means for storing information input by the input means; The ophthalmologic measuring device is characterized in that it is equipped with a second storage means for storing information for each measurement according to the information obtained by the measurement, and a control means for operating each of the means.

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

FIG. 1 shows an optical system showing one embodiment of the present invention. During corneal shape measurement, visible light emitted from the ring-shaped strobe 1 illuminates a circular slit 3 provided on the opposite side of the collimator ring lens 2 to the eye E to be examined. This 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 positioned at an infinity point, so that the light projected from that infinity point is The cornea Ec of the eye E to be examined is illuminated. Since the surface of the cornea Ec is like a convex mirror, it forms a corneal reflection image Sa of the slit 3, and this corneal reflection image Sa is transmitted through the objective lens 4 and is converted into a visible light transmission/infrared light reflection image. The light passes through a mirror 5 and a half mirror 6, passes through a multi-hole aperture 7, is further deflected by a prism, and is re-imaged onto a -dimensional position detection 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 element 8a -8e, respectively. As a result, the corneal reflection image s
The coordinates of five points in b will be detected, and by substituting the coordinates of these five points into the general formula of the quadratic curve, AX2+BXY+CY2+DX+EY+F=0, and solving the simultaneous equations, the coefficients A to E are found.
General formula for an ellipse, (x-xo)” /a2+ (y-yo)” /b2=
Matadashi, x=Xcosθ−Y sinθy=Xsi
The astigmatic axis can be calculated from the angle θ by deforming the ellipse to nθ+Y cosθ, deriving the radius of curvature of the bibatic meridian with the angle ll5iEc from the major axis a and the minor axis of the ellipse.

On the other hand, in the case of refractive power measurement, as shown in FIG.
The fundus projection chart 12 is illuminated through the light. This chart 12 includes three tree picks in three meridian directions that form an angle of 120 degrees with each other as shown in Figure 4.
2a to 12c are provided. The light from the light emitting diode 10 further passes through a relay lens 13 and is once imaged on a fundus illumination diaphragm 14, and then passes through a perforated mirror 15° and a relay lens 16, and since it is infrared light, it is focused on a dichroic mirror 5. The light is reflected by the object lens 4 and is imaged on the pupil of the eye E to be examined, thereby illuminating the fundus Ef.

Furthermore, the slits 12a to 12c of the chart 12 pass through the relay lens 13.16 to form an image, and are projected by the objective lens 4 so as to be conjugate with the fundus for emmetropia. Fundus E
The reflected image from f passes through the objective lens 4 again, is reflected by the dichroic mirror 5 to form an image, and further passes through the relay lens 16 and is reflected by the perforated mirror 15. A diaphragm plate 17 is arranged on the reflection side of the perforated mirror 15, and this diaphragm plate 17 has six openings 17a to 17 as shown in FIG.
It has f. And openings 17a and 17d, 17
b and 17e, and 17c and 17f correspond to each other and form one channel. The fundus illumination diaphragm 14 and the diaphragm plate 17 are arranged at 14A and 1 in FIG. 6 on the pupil of the eye E to be examined.
The image is formed as shown at 7A, and the projection system and measurement system of the chart 12 are separated.

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 lateral direction of the one-dimensional position detection element 21, and imaged onto three detection elements 21a to 21c. The prism 19 is shown in FIG. 7(a).
As shown in FIG. 7(b), it has six elements 19a to 19f, which separate images corresponding to the six openings 17a to 17f of the diaphragm plate 17. It 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 20a to 20c, and are imaged onto detection elements 21a to 21c. FIG. 8 shows the state of formation of this fundus image, and 22a to 22f represent fundus images formed corresponding to the openings 17a to 17f.

If the eye E to be examined is an ametropic eye, the light ray that exits the fundus Ef and passes through a point on the pupil will exit at an angle that corresponds to the refractive power. Ba,
The distance between the two fundus images 22 on each of the detection elements 21a to 21c 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 of the refractive powers can be substituted into the following equation, D=A sin (2ω + θ) + B. The spherical power, astigmatic power, and astigmatic axis can be calculated using Among the variables, ω represents the refractive power and the angle in the radial direction, and the constants aA, B, and θ correspond to the degree of astigmatism, the average refractive power, and the astigmatic axis, respectively.

To align the eye E and the instrument, the objective lens 4 passes through the dichroic body mirror 5 and reflects the half mirror 6, and the light rays from the anterior segment of the eye are focused on the television imaging tube 24 by the television relay lens 23. , can be adjusted using a television monitor connected to the television image tube 24.

Furthermore, once the eye refractive power and the corneal shape are determined, the astigmatic power can be determined by subtracting the corneal astigmatic power from the total astigmatic power. That is, the total astigmatic power of the eye refractive power is Ct, and the astigmatic axis is AXt.
, the corneal astigmatism power is Cc, the astigmatism axis is AXc, the astigmatism power other than the cornea is Cr, and the astigmatism axis is AXr, then Cr 5in2AXr= Ct 5in2AXt-Cc
5in2AXcCr cos2AXr=ct cos
2AXt-CCcos2AXc, AXr = (1/2)tan-' ((Ct 5i
n2AXt-CC5in2AXc) / (Ct cos2AXt -Ca cos2AXc
))Cr= (Ct 5in2AXt - Cc 5in
2AXc)/5in2AXr.

FIG. 9 is a block diagram of the electric control circuit, and the same symbols as in FIG. 1 represent the same members. The signal from the above-mentioned one-dimensional position detection element 9 is input to the corneal shape signal processing circuit 25, and the signal from the -dimensional position detection element 21 is input to the eye refractive power signal processing circuit 26, processed, and then sent to the internal bus. 27. The internal bus 27 includes a CPU 28 that controls and calculates the entire system, a ROM 29 and a first RAM 30 that store control programs, and a battery VB and a power supply switching circuit 31 that store data even when the power is turned off. vg2 RAM32 that can hold contents
．． A video memory 33 for displaying characters such as measurement results on images and an interface 34 for inputting and outputting signals with other external input devices are connected.

A mix circuit 35 is connected to the video memory 33.
A signal from the television image pickup tube 24 is also input to this mix circuit 35, and is further output to a television monitor 36. The interface 34 includes a measurement switch 37 . A light emitting diode 10 for measuring eye refractive power, and a strobe drive circuit 38 for driving the ring-shaped strobe 1. Printer 39 for printing measurement results. A priority switch 40 that determines whether to prioritize corneal topography measurement, intraocular pressure measurement, or rupture power measurement.
is connected. Furthermore, the interface includes preset counters 43 and 44 that respectively preset the values set in the digital switch 41 for setting the number of measurements for corneal topography measurement and the digital switch 42 for setting the number of measurements for eye refractive power measurement. 34, and also from the interface 34 to the preset counter 43゜4.
4, a countdown signal S2 to the preset counter 43, and a countdown signal S2 to the preset counter 44.
A countdown signal S3 is connected to each.

When performing a measurement, first determine the number of measurements of eye refractive power measurement and corneal topography measurement and which one to perform first.For example, if priority is given to corneal topography measurement, the priority switch 40 is selected.
is turned on, and if the number of corneal shape measurements is three, the digital switch 41 is set to 3, and if the number of eye refractive power measurements is five, the digital switch 42 is set to 5.

Next, after performing alignment adjustment while viewing the outside image of the subject [H] displayed on the TV monitor 36 via the TV tube 24, when the measurement switch 37 is pressed, the preset signal S is sent from the interface 34. is output, and the numerical values set in the digital switches 41 and 42 are respectively set in the preset counters 43 and 44. continue,
When the countdown signal S2 is sent to the preset counter 43 to decrease the number of stored sets by 1 and the strobe drive circuit 38 is driven to cause the ring-shaped strobe l to emit light, the eye to be examined E
The reflected image sb from the cornea Ec is formed on the one-dimensional position detection element 9. The output signal from the −dimensional position detection element 9 is
Waveform shaping, amplification and A/D in the corneal shape signal processing circuit 25
After being converted, it is stored in the RAM 30. And R
The peak address of the waveform is determined from the signal stored in the AM 30 and stored in another address in the RAM 30.

This measurement is repeated until the value of the preset counter 43 becomes zero, and the peak address of the waveform is stored in the RAM 30 for each measurement.
to be memorized. When the value of the preset counter 43 becomes zero, the process immediately shifts to eye refractive power measurement. In that case, first, a countdown signal S3 is output to decrease the number of stored sets in the preset counter 44 by 1, and one light emitting diode IO is caused to emit light to project the fundus projection chart 12 onto the fundus Ef.
A reflected image 22 from the fundus Ef is formed on the one-dimensional position detection element 21. The output signal from the -dimensional position detection element 21 is input to the eye refractive power signal processing circuit 26, subjected to waveform shaping, amplification, and A/D conversion processing, and then stored in the RAM 30. Then, as in the case of corneal topography measurement, the peak address of the waveform is determined and stored in yet another address in the RAM 30. After that, measurements are repeated until the value of the preset counter 44 becomes zero, and the peak of the waveform for each measurement is stored in the RAM 3.
Store it as 0.

After both measurements have been completed, ie after the value of the preset counters 43, 44 has reached zero.

The measurement result for each measurement is calculated from the peak address of the corneal shape 14 constant signal and the peak address of the eye refractive power 14 constant signal stored in the RAM 30, and from both results obtained by averaging each, Calculate the astigmatism power and its axial degree by subtracting the corneal astigmatism power from the total astigmatism power and display it on the TV monitor 3.
6 and output to the printer 39 for printing if necessary.

At the time of the next measurement, the number of measurements has already been set in the digital switch, so there is no need to reset it, and the measurement can proceed directly. If you want to reverse the measurement order, just turn off the priority switch 40.Furthermore, if you only need corneal topography measurement, set the value of the digital switch 42 to zero, and the eye refractive power No measurements are taken.

If the waveform captured during measurement is lower than the predetermined value due to movement or blinking of the eye E, the measurement may be performed again without subtracting the values of the preset counters 43 and 44.

In the above-described embodiment, the number of measurements and the counter are set using hardware, but the number of measurements is set in a battery-backed memory such as the RAM 32 from a keyboard or switch (not shown), and the program is executed. It is also possible to perform a countdown at the top.

[Effects of the Invention] As explained above, the ophthalmological measuring device according to the present invention can perform eye refractive power measurement and corneal shape measurement with the same device, and the number of measurements and order of each measurement can be programmed arbitrarily. Since each measurement result can be averaged automatically, multiple measurements can be performed continuously in one measurement operation, significantly reducing the time and effort required for inspection compared to conventional methods. It has the effect of reducing the

[Brief explanation of drawings]

The drawings show an embodiment of the limited-field measuring device according to the present invention, and FIG. 1 is an optical layout diagram, FIG. 2 (a) is a diagram of the relationship between a multi-hole diaphragm and a prism, and (b) is a cross-sectional view of the prism, Figure 3 is a diagram of the relationship between the detection element and the corneal reflection image, Figure 4 is a diagram of the arrangement of slits in the fundus projection chart, Figure 5 is a front view of the aperture of the aperture plate, and Figure 6. 7(a) is a front view of the prism element, (b) is its cross-sectional view, and FIG. 8 is the detection element and fundus image. FIG. 9 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 is a gicroic mirror,
6 is a half mirror, 17 is a multi-hole aperture, 8 is a prism, 9
1 is a detection element, 10 is a light emitting diode, 12 is a fundus projection chart, 14 is a fundus illumination diaphragm, 15 is a perforated mirror, 1
7 is an aperture plate, 19 is a prism, 20 is a cylindrical lens, 21 is a detection element, 24 is a television image pickup tube, 25 is a corneal shape signal processing circuit, 26 is an eye refractive power signal processing circuit, 2
7 is internal bus, 28 is microprocessor, 29 is RO
M, 30. 32 is a RAM, 33 is a video memory, and 34 is an interface. 35 is a mix circuit, 36 is a TV monitor, 37 is a measurement switch, 38 is a strobe drive circuit, 39 is a printer,
40 is a priority switch, 41.42 is a digital switch,
43 and 44 are preset counters. Patent applicant Canon Co., Ltd. Figure 1 ((1) Figure 2 Figure 3 Collection 7

Claims (1)

[Claims] 1. An ophthalmological measuring device having an eye refractive power measuring optical system and a corneal shape measuring optical system that partially share an optical system,
an input means for inputting and setting the number of measurements for eye refractive power measurement and the number of measurements for corneal shape measurement; a first storage means for storing information input by the input means; 1. An ophthalmological measuring device comprising: second storage means for storing information for each measurement according to the information obtained by the measurements; and a control means for operating the respective means. 2. The control means continuously measures the number of measurements stored in the first storage means, stores the detection signal obtained in each measurement in the second storage means, and completes all measurements. The ophthalmological measuring device according to claim 1, wherein the measurement result is obtained by performing calculations after the calculation is performed. 3. The control means calculates the average values of the corneal shape and eye refractive power for each measurement from the measurement results of the respective measurements, and calculates the total astigmatic power of the eye to be examined from the corneal shape/average value and the eye refractive power average value. The ophthalmologic measuring device according to claim 1, wherein the astigmatic power and its axis angle are calculated by removing the corneal astigmatic power from the ophthalmological measuring device. 4. The control means, prior to each measurement, subtracts 1 from the number of measurements stored in the first storage means for each measurement, and repeats the measurement until the number becomes zero. Ophthalmological measuring device. 5. The control means compares the 14 constant signal obtained in each measurement with a predetermined value, and if it is smaller than the predetermined value, the control means
The ophthalmologic measuring device according to claim 4, wherein re-measurement is performed without subtracting the number of measurements stored in the storage means.