JPS61293428A - Apparatus for measuring eye refraction power - 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 eye refractive power measurement device that can objectively measure the accommodation power of an eye to be examined.

11 Conventionally, there has been a subjective method in which the eye to be examined visually recognizes a visual acuity test index through a corrective lens system capable of converting the refractive power, and the distance refractive power of the eye to be examined is measured based on the response of the eye to be examined. Ocular refractive power measuring devices are known. Further, a measurement target image is photoelectrically detected on the fundus of the eye to be examined, the measurement target image is projected onto the fundus of the eye to be examined, and this measurement target image is photoelectrically detected.

An objective refractive power measurement device that objectively measures the distance refractive power of an eye to be examined is also known.

By the way, in eye refractive power measurement, it is necessary to measure not only the distance refractive power but also the near point position to which the subject's eye can exert m muscle strength.

In this case, in the conventional device described above, the refractive power of the eye to be examined is corrected based on the distance refractive power obtained by measurement, and in this state, the visual acuity test chart is moved to the near point position, and then Accommodative power was measured based on the subject's responses.

However, in this type of accommodative measurement, the accommodative ability is measured solely by the test subject's response;
The subject himself/herself cannot know how much accommodation power is actually working, making it difficult to accurately measure accommodation power.

In order to solve the problems of the prior art, the present invention for fortune telling uses a chart projection system for projecting an examination chart image onto the fundus of the examinee's eye using visible light, and an invisible image onto the fundus of the examinee's eye. A measurement target projection system for projecting a measurement target image using light, and an AM system for converting the measurement target image into a visible image for observation, and determining the focused state of the inspection chart image. and the in-focus state of the measurement target image can be changed, and after the in-focus state of the inspection chart image changes, the a
The present invention is characterized in that it includes an accommodative force measurement system that measures an accommodative force based on a change in the focusing state of a measurement target image observed in the m-system.

5.1 Project the index plate placed at the far point position onto the fundus of the eye to be examined as a measurement target image using invisible light.

At the same time, a chart image placed at the far point position is projected onto the fundus of the subject's eye using visible light, and then the chart plate or projection lens of the chart projection system is moved toward the near point position, thereby splitting the measurement target image. If the position at which a is detected is defined as the near point position, then the difference between the near point position and the far point position corresponds to the accommodation force.

Embodiments of the eye refractive power measuring device according to the present invention will be described below based on the drawings.

FIG. 1 is a diagram showing an optical system of an eye refractive power measuring device according to the present invention.

In Fig. 1, numeral 1 is a target image projection system, 2 is an imaging optical system, 3 is a shared optical system shared by the target image projection system 1 and the imaging optical system 2, 4 is a chart projection system, and 5 is an aiming optical system. 6 is the eye to be examined, and 7 is the anterior segment of the eye. The target image projection system 1 has the function of projecting target light onto the fundus 8 of the eye to be examined 6 via the shared optical system 3 to form a target image on the fundus 8, and includes a light emitting element 9, a condenser lens, 10. Indicator plate 11, reflecting prism 12.
13, a relay lens 14, a reflecting prism 15, and a half-moon diaphragm plate 16. Here, light emitting element 1
o emits infrared light, which is invisible light, and this infrared light is turned into a parallel light beam by a condenser lens 1o and illuminates the index plate 11. As shown in FIG. 2, the index plate 11 has slits lla to lid formed therein, and four deflection prisms lie to llb are attached thereto. Thereby, the index plate 11 is illuminated with infrared light to form measurement target light, and the polarization prism li
e to llh deflect the target light in a direction perpendicular to the longitudinal direction of the slit.

On the other hand, the shared optical system 3 includes a slit prism 17, an image rotator 18, an objective lens 19, and a beam splitter 20. Then, the target light from the index plate 11 is reflected by the reflecting prism 12.1.3.15 and guided to the semilunar diaphragm plate 16, where it passes through the semilunar holes 16a, 16.
b, is reflected by the reflective surface 17a of the slit prism 17, and then passes through the pupil of the eye 6 to be examined via the image rotator 18, objective lens 19, and beam splitter 20, and is projected onto the fundus 8. It has become. The half-moon diaphragm plate 16 is arranged with respect to the objective lens 19 so as to be conjugate with the pupil position of the eye 6 to be examined at an appropriate position, and blocks reflected light harmful to measurement from the anterior segment 7 of the eye 6 to be examined. This allows light to enter the eye 6 to be examined.

Further, the image rotator 18 is connected to the optical axis 0 of the shared optical system 3.
By rotating by 0/2 angle around the fundus 8
The measurement target image formed in is rotated by an angle of θ in the meridian direction of the eye 6 to be examined.

The reflected light of the measurement target image projected onto the fundus 8 is transmitted to a beam splitter 20, an objective lens 19. The light is guided to the imaging optical system 2 via the slit hole 19a of the slit prism 19, the aperture 21a formed in the center of the aperture stop plate 21, the relay lens 22, and the reflection prism 23. Further, the Sekiguchi diaphragm plate 21 is arranged at a position conjugate with the pupil of the eye 6 to be examined, and guides reflected light passing through the center of the pupil to the relay lens 22. Furthermore, the imaging optical system 2 includes a reflecting mirror 24, a moving lens 25, and a reflecting mirror 26.
, a half mirror 27, and an imaging lens 28, which guides the reflected light of the measurement target image formed on the fundus 8 to the photocathode 29a of the imaging device 29, and forms the measurement target image on the photocathode 29a. It is designed to form an image. Here, when the image rotator 18 is rotated by an angle θ/2 around the optical axis Q as described above, the measurement target image is rotated by an angle θ in the rotation direction. Since the reflected light of the measurement target image passes through the image rotator 18 again, the measurement target image is rotated by an angle θ in the opposite direction to the rotation direction of the image rotator 18, and the photocathode 29a of the imaging device 29 is rotated. A measurement target image facing a predetermined direction is formed irrespective of the rotation of the image rotator 18.

The chart projection system 4 includes a tungsten lamp 30 as a visible light source, a color correction filter 31, a condenser lens 32,
Chart board 33, moving lens 34, reflecting mirror 36.3
7, a relay lens 38, a reflecting mirror 39, and an objective lens 40. Here, chart board 33
is illuminated by a tungsten lamp 30 via a condenser lens 31 and a color correction filter 32, and the wavelength of the light emitted from the tungsten lamp 30 is selected by the color correction filter 32, and ranges from 400 nm to 700 nm.
Only visible light down to nm is transmitted. A chart 33a as shown in FIG. 3 is formed on this chart board 33, and the light from the chart 33a is guided to a moving lens 34 and a relay lens 38, and the optical path is changed by a reflecting mirror 36°37.39. The light is converted, passes through the relay lens 38 and the objective lens 40 , is guided to the beam splitter 41 , and is projected toward the eye 6 via the beam splitter 20 . Furthermore, the moving lens 34 is
It is arranged so as to be movable in the direction of its optical axis, and when performing objective measurement, it is arranged at a position that causes the eye 6 to be examined to see far-sighted or misty vision in accordance with the refractive power of the eye 6 to be examined. Measurement can be performed with the accommodation power of the eye 6 to be examined removed.

Further, the aiming optical system 5 is for forming an image of the anterior segment 7 of the eye 6 to be examined on the photocathode 29a of the imaging device 29, and the light flux reflected by the anterior segment 7 is transmitted to the beam splitter 20.
．． 41 and a reflecting mirror 42, the light passes through an imaging lens 43, a half mirror 27, and an imaging lens 28, and an anterior segment image is formed on a photocathode 29a of an imaging device 29.

The imaging device 29 is connected to a television monitor 44,
45 is its display surface. On this display surface 45, an image formed on the photocathode 29a based on a video signal from the imaging device 29 is displayed as a visible image. In FIG. 1, 46 is a measurement target image formed by the imaging optical system 2, and 47 is an anterior segment image formed by the aiming optical system 2.

Here, when the target image 46 displayed on the display surface 45 of the television monitor 44 is in focus on the fundus 8, as shown in FIG.
The distance 2□ between a and the distance I2 between the lower pair of target images 46b
2 matches. For example, if the measurement target image is focused in front of the fundus 8, the interval Q1 will be smaller than the interval Q□ as shown in FIG. Assuming that the object is in focus, the distance Q8 will be larger than the distance n2, as shown in FIG.

During objective measurement of refractive power, the index plate 11 is moved to the surface distance 121. of the measurement target image. The eye refractive power is determined by the amount of movement of the index plate 11 at this time. In this case, the moving lens 25 is driven integrally with the index plate 11 while maintaining a conjugate relationship.

Next, the measurement circuit shown in FIG. 7 will be explained.

A portion of the video signal from the imaging device 29 described above is input to the television monitor 44 to display an image of the anterior segment of the eye, and the other portion is input to the video signal extraction circuit based on a command signal from the extraction command circuit 51. 52, the video signal regarding the measurement target image is extracted. Then, the extracted video signal is subjected to waveform processing in a rectangular wave generation circuit 53 to convert it into a predetermined rectangular wave, and the obtained rectangular wave is processed by a video signal level determiner 54. While the brightness level, that is, the light intensity level of the measurement target image 46 is detected, the signal interval, that is, the interval of the measurement target image 46 is detected by the target image position detection circuit 55.

Here, signal processing of the output signals from the video signal level determiner 54 and the target image position detection circuit 55, or each signal to be described later, is performed by the CPU 50 of the microcomputer.

The CPU 50 includes an accommodative force measurement start switch 56 that is operated at the start of accommodative force measurement, a chart board setting switch 57 that is operated when moving the chart board 33, and an index board 1.
1 and a drive switch 58 for moving the movable lens 25, and an automatic measurement start switch 59 for starting automatic measurement.

Further, the CPU 50 controls a drive control section 60, which is a first drive control section 61. It consists of a second drive control section 62 for rotating the image rotator 18 around the optical axis, and a third drive control section 63 for moving the moving lens 34 of the chart projection system 4 along the optical axis. . In addition, CPU5
0 is a pre-installed predetermined automatic measurement program 64
Alternatively, an accommodation force measurement program 65 is executed, and each measurement result is sequentially recorded by a printer 67.

Next, the operation of the eye refractive power measuring apparatus configured as described above will be explained with reference to the flowchart shown in FIG.

First, when execution of arithmetic processing by the CPU 50 is started by turning on the power, etc., when the automatic measurement switch 59 is turned on in step 100, the CPU 50 calls the automatic measurement program 64, and the following measurements are performed according to this.

First, in the initial setting in step 101, the first drive control section 61 sets the index plate 11 to the O diopter - position, and the second drive control section 62 sets the image rotator 18.
to the Oo position, and a third drive control unit 63 controlled in synchronization with the first drive control unit 61 moves the movable lens 34 to the O diopter position, that is, the chart board 33 to the far point position. .

In the subsequent step 102, the target image position detection circuit 5
Based on the output from 5, the distance Ω of the measurement target image 46
1, I22 is detected. When this interval Ω□, Q2 is detected, the CPU 50 calculates the interval difference Q knee Q2 until the interval difference 121-Q□ becomes 0, that is, the position where the measurement target image 46 is focused on the fundus 8. up to, indicator board 1
1 and the moving lens 25 move together along the optical axis. In conjunction with this movement, the moving lens 34 of the chart projection system 4 moves (steps 102 to 105), so that the eye 6 to be examined is kept in a foggy state at all times. When the interval difference Q1-Q becomes O, the position of the moved indicator plate 11 is read (step 106), and the refractive power in the Oo meridian direction is obtained based on this moved position.

Next, while keeping the position of the index plate 11 fixed, the image rotator 18 is rotated by, for example, 6 degrees (the direction of the meridian to be measured).
The distance difference α1-Q2 corresponding to each rotational position is read (steps 107 to 109).
). Here, the refractive power D8 in the θ direction is obtained by calculating the sum of the diopter value corresponding to the stop position of the indicator plate 11 and the diopter value corresponding to the interval difference Q1-Ω2 value. The refractive power D8 has a relationship with the spherical power A, the astigmatic power B, and the astigmatic axis α as shown in the following equation (1).

DB = A + B cos (θ - α) - (1) Therefore, the refractive power D obtained in each meridian direction (15 meridian directions)
8□~DB0. Based on the method of least squares, the spherical power A
, astigmatic power B, and astigmatic axis α are calculated (steps 110 and 111), and these calculation results are displayed or recorded as measured values on the television monitor 44 and printer 67, respectively (steps 112 and 1).
13) The measurement of continuous refractive power by automatic measurement is completed.

Next, when the accommodation force measurement program 65 is to be executed, the process moves from step 114 to step 115 in which it is determined whether or not to execute it. When the accommodative force measurement start switch 56 is turned on, the CPU 50 calls the accommodative force measurement program 65, and the following accommodative force measurements are performed according to this program. In addition, in this accommodative force measurement, the chart board 33 of the chart projection system 4 functions as a visual acuity board for measuring the accommodative force.

When executing this program 65, first.

In step 115, the moving lens 34. The index plates 11 are each initialized.

With this initial setting, the chart board 33 and the index board 11 are placed at approximately the far point position of the eye 6 to be examined, and the position scale at this far point position is read (steps 116 and 117).

In this case, a measurement target image using invisible light and a chart image using visible light are superimposed and projected onto the eye 8 to be examined, but only the chart image is visible to the examinee. Further, at this far point position, the subject can focus on the chart image, and the measurement target image on the display surface 45 of the television monitor 44 at this time is as shown in FIG.

It can be observed that both the intervals Ω0 and Ω2 are substantially coincident.

Next, the examiner turns on the drive switch 57 (Step 118), and moves the index plate 11 and chart plate 33 (or the projection lens 34) together in a synchronized state in the optical axis direction, that is, in the periapsis direction. Step 119゜120),
As shown in FIG. 5, the measurement target image 4 on the display surface 45
6 starts to split, their movement is stopped (step 121). This time is regarded as the periapsis position and the position scale is read (step 122), the accommodation force is calculated from the difference in the position scale between the periapsis position and the far point position (step 123), and the result is displayed on the television monitor 44. , is recorded by the printer 67 (steps 124, 125).

In this example, after the distance refractive power is measured by automatic measurement, the accommodative power is measured without correcting the subject's astigmatism. A cylindrical power conversion lens is inserted in each case, and the test subject's astigmatism is corrected using the cylindrical power conversion lens based on the subject's astigmatic power and astigmatism axis obtained by automatic measurement, and then the accommodative power is measured. With this configuration, more accurate measurement results can be obtained.

According to the present invention, the accommodative power of the eye to be examined is measured based on the change in the focus state of the measurement target image accompanying the change in the focus state of the test chart image. This makes it possible to objectively measure the accommodation force, and more accurate measurement results can be obtained.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of the optical system of the automatic eye refractive power measuring device according to the present invention, Fig. 2 is a perspective view of an index plate constituting the optical system, and Fig. 3 is a chart plate constituting the optical system. FIG. 4 to FIG. 6 are schematic diagrams showing various aspects of the imaging state of the measurement target image formed by the optical system, and FIG. 7 is a measurement circuit diagram for driving the device. 8th
The figure is a flowchart for executing a program by the measurement circuit. 1...Measurement target image projection system. 4... Chart projection system, 6... Eye to be examined, 29...
・Imaging device, 33... Chart board, 46...
- Measurement target image, 5o...CPU. 65...Adjustment force measurement program. Figure 2 Figure 4 Figure 5 Figure 6

Claims (4)

[Claims] (1) a chart projection system for projecting a test chart image onto the fundus of the subject's eye using visible light; a measurement target projection system for projecting a measurement target image onto the fundus of the subject's eye using invisible light; an observation system for converting the measurement target image into a visible image for observation, and configured to be able to change the focus state of the measurement target image simultaneously with changing the focus state of the inspection chart image. and an accommodation force measurement system that measures accommodation power based on a change in the focus state of the measurement target image observed by the observation system in accordance with a change in the focus state of the inspection chart image. An eye refractive power measurement device characterized by: (2) The measurement target image projection system is configured so that the time when the split measurement target image is formed on the fundus of the subject's eye is the time when the measurement target image is out of focus. The eye refractive power measurement device according to scope 1. (3) The chart projection system consists of an examination chart board and a projection lens for projecting the light beam from the chart board onto the fundus of the eye to be examined, and moves at least one of the chart board or the projection lens along the optical axis. 2. The eye refractive power measuring device according to claim 1, wherein the eye refractive power measuring device is configured such that the focusing state of the chart image on the inspection chart board can be changed by changing the focus state of the chart image on the inspection chart board. (4) The accommodative power measuring device moves the inspection chart board or projection lens close from the initial setting position corresponding to the distance refractive power to the position where the measurement target image observed by the observation system is out of focus. 4. The eye refractive power measuring device according to claim 3, further comprising calculation means for moving the eye toward a point and calculating the accommodative power of the eye to be examined based on the amount of movement.