JPS61293430A - 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 accommodative power of an eye to be examined.

U1 right Conventionally, a subjective method that allows the eye to be examined to visually recognize visual acuity test indicators through a corrective lens system that can convert the refractive power, and measures the distance refractive power of the eye to be examined based on the eye to be examined's response. Ocular refractive power measuring devices are known. In addition, the 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, this measurement target image is detected photoelectrically, and the distance refractive power of the eye to be examined is objectively determined. Objective refractive power measurement devices are 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 eye to be examined can exert its accommodative power.

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.

Problem 1: However, in this type of accommodation measurement, accommodation is measured only by relying on the test subject's responses.
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 provides a measurement target projection system for projecting a measurement target image onto the fundus of an eye to be examined using invisible light, and a measurement target projection system for projecting a measurement target image onto the fundus of an eye to be examined. A measurement system that photoelectrically detects the focused state of the eye to be examined, and a measurement system that projects a chart I-image for inspection onto the fundus of the subject's eye using visible light, and that changes the chart image in conjunction with changes in the focused state of the measurement target image. A chart projection system whose focus state can be changed, and the inspection chart or projection lens of the chart projection system is moved by a predetermined amount in the direction of the near point from its initial setting position to adjust the focus state of the chart image. The eye is characterized by being provided with an accommodative force measurement unit that measures the accommodative force of the eye to be examined by changing the defocus amount of the measurement target image accompanying this change using a signal from the measurement system. be.

Negative W An index plate placed at the far point position is projected 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 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 a predetermined distance (
For example, if the measurement target image is moved by a distance of 30 cm (equivalent to the distance of clear vision) and the measurement target image is out of focus, the adjustment force can be calculated based on the amount of defocus.

Loss of Garden ■ Hereinafter, embodiments of the eye refractive power measuring device according to the present invention will be described 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, ■ 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 a 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 light emitting elements 9. Condenser lens 10, index plate 11, reflective prism 12
．． 13, a relay lens 14, a reflecting prism 15, and a half-moon diaphragm plate 16. Here, the light emitting element 10 emits infrared light, which is invisible light, and this infrared light is turned into a parallel light beam by the condenser lens 10 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 deflection prisms 11e 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 prisms 12, 13, and 15 and guided to the meniscal diaphragm plate 16, where it passes through the semilunar holes 16a and 16b.
The light passes through the pupil of the eye 6 to be examined and is projected onto the fundus 8 via the image rotator 18, objective lens 19, and beam splitter 20.・The half-moon diaphragm plate 16 is connected to the objective lens 19, and the eye to be examined 6 is in the proper position.
It is arranged so that it is conjugate with the pupil position of eye 6, and
This is to block reflected light that is harmful to measurement from the anterior ocular segment 7 of the eye, and to allow target light to enter the eye 6 to be examined. In addition, the image rotator 18 rotates by an angle of θ/2 around the optical axis α of the shared optical system 3, thereby moving the measurement target image formed on the fundus 8 by an angle of θ in the meridian direction of the eye 6 to be examined. It is something that is rotated.

The reflected light of the measurement target image projected onto the fundus 8 is transmitted to a beam splitter 20. 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 aperture diaphragm plate 21 is arranged at a position conjugate with the pupil of the eye 6 to be examined, and is adapted to guide reflected light passing through the center of the eye 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 Z7, 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 directs the reflected light onto the photocathode 29a. A measurement target image is formed. Here, when the image rotator 18 is rotated by an angle θ/2 around the optical axis α 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 8, and the photocathode of the imaging device 29 is rotated. A measurement target image oriented in a predetermined direction is formed on the image rotator 29a regardless 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 345 reflecting mirror 36.3
7. It is roughly composed of 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 is directed to an optical path by reflecting mirrors 36, 37 and 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 subject's eye 6 via the beam splitter 2o. Further, the movable lens 34 is disposed so as to be movable in the direction of its tip axis, and during objective measurement, the eye 6 to be examined undergoes far-sighted vision or cloudy vision in accordance with the refractive power of the eye 6 to be examined. It is arranged at such a position that 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.
．． After being reflected by 41 and reflecting mirror 42, the light passes through imaging lens 43, half mirror 27, and imaging lens 28, and an anterior segment image is formed on photocathode 29a of 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.
a distance Q1 and a distance Q2 between the lower pair of target images 46b
are the same. for example.

Assuming that the measurement target image is focused in front of the fundus 8, the interval α becomes smaller than the interval Q2, as shown in FIG. Then, as shown in FIG. 6, the interval Q□ is larger than the interval Q2.

When objectively measuring refractive power, move the index plate 11 so that the interplanar distances Ω1 and °C2 between the measurement target and the image match,
The eye refractive power is determined from the amount of movement of the index plate 11 at this time. In this case, the moving j-nons 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.3 A part of the video signal from the above-mentioned imaging device 29 is input to the television monitor 44 to display an image of the anterior segment of the eye, and the other part is input to the television monitor 44 to display an image of the anterior segment. is extracted as a video signal regarding the measurement target image by the video signal extraction circuit 52 based on a command signal from the extraction command circuit 51. 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 converted into a predetermined rectangular wave by a video signal level determiner 54.
Therefore, its brightness level, that is, the measurement target image 46
On the other hand, the signal interval, that is, the interval between the measurement target images 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 a microcomputer CPtJ50.

The CPU 50 operates an accommodation force measurement start switch 56. which is operated at the start of accommodation force measurement. Indicator board 11 and chart board 3
drive switch 57 for moving the chart board 3;
A chart board setting switch 58, which is operated to fix the position of No. 3, and an automatic measurement start switch 59, which is used to start automatic measurement, are respectively controlled. Further, the CPU 50 controls a drive control section 60, which includes a first drive control section 61 for moving the index plate 11 and the movable lens 25 along the optical axis, and an image rotator 18. A second drive control unit 62. for rotating the optical axis around the optical axis. It consists of a third drive control section 63 for moving the chart plate 33 or the moving lens 34 of the chart projection system 4 along the optical axis. Here, the first drive control section 61 and the third drive control section 6
3 means that it is controlled in a synchronous state by the CPU 50 when measuring the accommodation force. Note that the CPU 50 is configured to execute a predetermined refractive power measurement program 64 or accommodation power measurement program 65 installed in advance, 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 CPUSO starts by turning on the power, etc., when the auto measurement switch 59 is turned on in step 100, the CPU 50 calls the refraction power 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, the second drive control section 62 sets the image rotator 18 to the 06 position, and the third drive control section 63 sets the chart to the O diopter position. Settings are made to move the plate 33 to the same diopter position as the index plate 11.

In the subsequent step 102, the target image position detection circuit 5
Based on the output from 5, the measurement target image interval I21
．． n2 is detected. When the intervals Q1 and Q2 are detected, the C:PU 50 calculates the interval difference Q knee Q2 until the interval difference Ω□-Q2 becomes O, that is, the measurement target image 46 is focused on the fundus 8. The index plate 11 and the moving lens 25 move together along the optical axis to the desired position. In conjunction with this movement, the chart plate 33 or moving lens 34 of the chart projection system 4 moves (steps 102 to 105).
, the eye 6 to be examined is kept in a foggy state at all times. Then, when the interval difference 2, -Ω2 becomes O, the position of the moved index plate 11 is read (step 106).
, the refractive power in the 00 meridian direction is obtained based on this movement position.

Next, while the position of the index plate 11 is fixed, the image rotator 18 is rotated, for example, 15 times every 6° (the direction of the meridian to be measured), and the interval difference 21-Ω2 corresponding to each rotational position is read. (Stip 107-109)
. 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 Q1-22 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).

D! l: A+B cos (θ-α) (1) Therefore, the refractive powers DI to D obtained in each meridian direction (15 meridian directions), 1. Based on the method of least squares, the spherical power A
, astigmatism power B, and astigmatism axis α are calculated, respectively (steps 110 and 111). These calculation results are then displayed or recorded as measured values on the television monitor 44 and printer 67, respectively (step 112.11).
3) The measurement of distance refraction 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 movable lens 34 and the index plate 1 are initially set at positions corresponding to the distance refractive power obtained by executing the refractive power measurement program 64 described above. With this initial setting, the chart board 33 and the index board 11
is placed at approximately the far point position of the eye 6 to be examined, and the position scale of this far point position is read (steps 116 and 117).
The corresponding diopter value DG is read.

In this case, a measurement target image using invisible light and a chart image using visible light are projected onto the eye 8 in a superimposed manner, 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 accommodation force is measured based on this chart image.

On the other hand, at the time of initial setting, the chart plate 33 and the index plate 11 are moved to the far point position, and the measurement target images are in a state where the surface spacing Ω Q2 is approximately the same, as shown in FIG. The difference between the surface spacings Q1 and Q2, ie, -Ω2, is constantly photoelectrically detected by the measurement system.

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 at a predetermined periapsis position (for example, (a distance equivalent to 30 cm from the anterior segment of the subject's eye) (Step 11)
9,120). 7.1. When the movement operation for a predetermined distance is completed (step 121), the amount of defocus of the measurement target image at that time is detected (step 122), thereby obtaining the coefficient k for calculating the accommodation force, and The above six chips 11. are added to the coefficient k. The accommodation force is calculated by multiplying the distance of the difference between the far point position and the near point position determined by the corresponding accommodation force constant (step 123). The obtained accommodation power diopter value is displayed on the television monitor 44 (step 124), and at the same time, the printer 67
The results are recorded (step 125).

Note that if the amount of defocus by the measurement target image is not detected after the index plate 11 and chart plate 33 are moved, this means that the eye to be examined does not require a corrective lens for near vision.

In addition. In this example, after measuring the distance refractive power by automatic measurement, the accommodative power is measured without correcting the subject's astigmatism. The system is configured so that the astigmatism of the examinee is corrected using the cylindrical power conversion lens based on the astigmatism power and astigmatism axis of the examinee obtained through automatic measurement by inserting the conversion lens, and then the accommodative power is measured. more accurate measurement results can be obtained.

According to the present invention, the inspection chart image and the measurement target image are moved 8 times from the far point position to the predetermined near point position, and based on the defocus amount of the measurement target image at that time, Since the accommodative power of the subject's eye can be measured, it becomes possible to objectively measure the accommodative power, and the measurement can be performed extremely easily.

[Brief explanation of the drawing]

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 measuring circuit. 1... Measurement target image projection system, 4... Chart projection system, 6... Eye to be examined, 29
...imaging device, 33...chart board, 4
4...TV monitor. 46...Measurement target image, 50...CPU, 65
...Adjustment force measurement program. Figure 2 Figure 3 Figure 6

Claims (3)

[Claims] (1) A measurement target projection system for projecting a measurement target image onto the fundus of the examinee's eye using invisible light, a measurement system that photoelectrically detects the focused state of the measurement target image, and a visible light onto the fundus of the examinee's eye. and a chart projection system capable of projecting a chart image for inspection using a chart projection system and changing the focused state of the chart image in conjunction with the changing operation of the focused state of the measurement target image, The chart or projection lens is moved by a predetermined amount in the near point direction from its initial setting position to change the focus state of the chart image, and the defocus amount of the measurement target image due to this change is detected by a signal from the measurement system. 1. An eye refractive power measuring device comprising an accommodative power measuring section that measures the accommodative power of an eye to be examined by detecting the accommodative power. (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) Eye refractive power measurement according to claim 1, wherein the measurement system has a calculation means for calculating the distance refractive power of the eye to be examined from the signal indicating the focused state of the measurement target image. Device.