JPS61293429A - 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.

Traditionally, the subject's eye is made to visually recognize a visual acuity test index through a corrective lens system capable of converting the refractive power, and the distance refractive power of the subject's eye is measured based on the patient'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 whether the accommodation power can be applied to the near point position of the subject's eye misalignment.

In this case, in the conventional device described above, the refractive power of the eye to be examined is corrected based on the measured distance refractive power, 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 test subject's responses.

My eyes feel numb. However, in this type of accommodative power measurement, the accommodative power is measured only by relying on 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 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 system for projecting a measurement target image onto the fundus of an eye to be examined. A measurement system that photoelectrically detects the focus state and a test chart that is projected onto the fundus of the subject's eye using visible light, and changes the focus state of the chart image in conjunction with the movement of changing the focus state of the measurement target image. The chart projection system is equipped with a detection means for detecting the focused state of the measurement target image based on the signal from the measurement system, and the The present invention is characterized by being provided with an accommodative force measuring section that measures the accommodative force for optometry.

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 position is projected onto the fundus of the eye to be examined using visible light, and then the chart plate or projection lens of the chart projection system is moved toward the near point position, thereby making the measurement target image non-linear. The position at which the object is in focus, that is, the near point position, can be confirmed on a display means such as a television monitor, and the difference between the near point position and the far point position can be determined as the accommodation force.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the eye refractive power measuring device according to the present invention will be described below with reference to the drawings.

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

In FIG. 1, 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, index plate 11, reflection prism 12.
13. Relay lens 14, reflective prism 15. It is roughly constituted by a half-moon aperture plate 16. Here, light emitting element 1
0 is.

It 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 Ilb are attached thereto. Thereby, the index plate 11 is illuminated with infrared light to form measurement target light, and the polarization prisms 110 to l
lh deflects 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.
, and is reflected by the reflecting surface 17a of the slit prism 17, and then the image rotator 18, the objective lens 19. The light passes through the pupil of the eye 6 to be examined via the beam splitter 20 and is projected onto the fundus 8 . The half-moon diaphragm plate 16 is connected to the objective lens 19 when the subject's eye 6 is in an appropriate position.
It is arranged so that it is conjugate with the pupil position of eye 6, and
This is to block reflected light harmful to measurement from the anterior segment 7 of the eye and allow target light to enter the eye 6 to be examined. Furthermore, by rotating the image rotator 18 by an angle of θ/2 around the optical axis of the shared optical system 3, the measurement target image formed on the fundus 8 is rotated 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, 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 aperture diaphragm plate 21 is arranged at a position conjugate with the pupil of the eye 6 to be examined, and is configured to guide 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 through a condenser lens 3 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 the wavelength range is 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 onto the eye 6 to be examined 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.
．． 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 Qi and the distance Q2 between the lower pair of target images 46b
are the same. For example, if the measurement target image is focused in front of the fundus 8, the interval Q1 will be smaller than the interval Q2 as shown in FIG. If so, the interval Q□ will be larger than the interval Ω2, as shown in FIG.

When objectively measuring refractive power, the index plate 11 is moved so that the surface distances Q and Q2 of the measurement target image match, and the eye refractive power is determined from the amount of movement of the index plate 11 at this time. becomes. 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 image signal is extracted as a video signal regarding the measurement target image. 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 to determine its luminance. While the 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 accommodation force measurement start switch 56 that is operated at the start of accommodation force measurement, an index board 11, and a chart board 3.
Drive switch 57° for moving 3 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. 8 around the optical axis, and a third drive control section 63 for moving the chart plate 33 or moving lens 34 of the chart projection system 4 along the optical axis. There is. 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 3O is designed 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 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 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 07 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 distance between the measurement target images Q, Q, Q2 is detected. When the intervals Ω8 and Ω2 are detected, cptjso calculates the interval difference Q□−fA2 until this interval difference +21−D,2 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 moving lens 3 of the chart projection system 4
In steps 102 to 105), the subject's eye 6 is kept in a foggy state at all times. And the interval difference +2. - When Q becomes O, the index plate 1 moved
1 position is read (step 106), and the refractive power in the 0° meridian direction is obtained based on this movement position.

Next, while keeping the position of the index plate 11 fixed, the image rotator 18 rotates, for example, 15 times every 6 degrees (the direction of the meridian to be measured), and the interval difference Q0-2□ corresponding to each rotation position is read. (Steps 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 Q knee a□ value. The refractive power D8 is a spherical power A and an astigmatic power B.

and the astigmatic axis α have a relationship expressed by the following equation (1).

DB = A + B cos (θ - α) - (1) Therefore, the refractive power D obtained in each meridian direction (15 meridian directions)
6□~D, 1. Based on the method of least squares, the spherical power A
, astigmatism power B, and astigmatism axis α are calculated (steps 11o, 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 continuous 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.

In executing this program 65, first, in step 115, the movable lens 34 and the index plate 11 are initially set to positions corresponding to the distance refractive power obtained by executing the refractive power measurement program 64 described above. Ru. 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 of this far point position is read (steps 116 and 117), and the corresponding diopter value is read. DQ 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, the chart plate 33 and the index plate 11 have been moved to the far point position, and the measurement target image is in a state where the interplanar distances i11 and Q2 are substantially the same, as shown in FIG. The difference between the surface spacings Q, Q2, ie, Q, -Ω2, is constantly detected photoelectrically in the measurement system, and is expressed by the relationship Q2<ε at the initial setting stage described above.

Here, ε□ is an extremely small amount, and when such a relationship exists, a fist mark is displayed on the television monitor 44.

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 toward the near point so that they have the same diopter value (step 118). Step 119,
120). During this time, the rectangle value corresponding to the defocus amount of the measurement target image is constantly detected (step 121), and a number of fist marks proportional to this defocus amount are displayed on the television monitor 44. In this case,
Chart board 33 and index board 11 by drive switch 57
During the movement process, the accommodation power of the eye 6 to be examined cannot follow quickly, so the number of displayed monkey marks temporarily increases, but after the operation of the drive switch 57 is stopped, the amount of movement decreases. When it is small, only a - mark is displayed.

When the chart board 33 and index board 11 are repeatedly moved by the ON operation of the drive switch 57, and two 1 marks are displayed after the operation is stopped, and the adjustment force no longer follows, the drive switch 57 is turned ON. Solve the continuation of (step 123), read the position scale at this time (step 124), and calculate Ds D from the diopter value DA corresponding to that position and the diopter value described above.
, A are determined, and the adjustment force is calculated based on these (step 125). Then, the obtained diopter value of the accommodation force is displayed on the television monitor 44 (step 126), and at the same time, the result is recorded by the printer 67 (step 127).

Note that in this embodiment, after measuring the distance refractive power by automatic measurement, the accommodative power is measured without correcting the subject's astigmatism. More accurate measurement results can be obtained by inserting a cylindrical power conversion lens, correcting the subject's astigmatism obtained by automatic measurement, and then performing accommodative force measurement. Furthermore, in this embodiment, the examiner turns on the drive switch 57 to make adjustments based on the detection results displayed on the television monitor 44, but it is also possible to automatically drive the drive switch 57 based on the detection signal from the measurement system. It may be configured as follows.

Hoho! As described above, according to the present invention, changes in the focus state of the measurement target image due to changes in the focus state of the inspection chart image are detected based on a simple method of displaying marks using a display means. Since the accommodative power can be measured in optometry, the accommodative power can be measured objectively, making it possible to measure the accommodative power more accurately and 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 44...
- TV monitor, 46...Measurement target image, 50...CPU. 65...Adjustment force measurement program.

Claims (5)

[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 in-focus 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 an inspection chart using a 100-degree-of-contact system and changing the focusing state of the chart image in conjunction with the changing operation of the focusing state of the measurement target image. In addition to providing a detection means for detecting a focused state of the target image,
An eye refractive power measurement device comprising an accommodative power measurement unit that measures the accommodative power of the eye to be examined based on changes in the measurement target image accompanying changes in the focus state of the chart image. (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. (4) The chart projection system consists of an examination chart board and a projection lens for projecting the light flux 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. (5) The accommodative power measurement section moves the chart board or projection lens toward the near point by observing with the display means from the initial setting position corresponding to the distance refractive power to the position where the measurement target image is in an out-of-focus state. 5. The eye refractive power measuring device according to claim 4, further comprising a calculation means for moving the eye, detecting the amount of movement, and calculating the accommodative power of the eye to be examined based on this amount of movement.