JPS61168331A - Objective automatic eye refractive power measuring device - 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 Application Field) The present invention relates to an objective automatic eye refractive power measurement device having a fixation chart projection system that causes a subject's eye to have a foggy vision.

(Prior art) Conventionally, a target image for measurement is projected onto the fundus of the eye to be examined using invisible light, the in-focus state of this target image for measurement is detected photoelectrically, and based on this detection result, the target image for measurement is projected onto the fundus of the eye to be examined. An objective automatic eye refractive power measurement device that measures the refractive power of a person is known.

In this objective type automatic eye refractive power measurement device, the line of sight of the eye to be examined is fixed in a predetermined direction, and a fixation chart using visible light is used to eliminate the accommodation power of the eye to be examined and make the eye to be examined into a foggy vision state. A fixation chart projection system is provided for projecting. This fixation chart is located a predetermined distance (for example, 3 diopters and 1 minute away) from the accommodation range of the eye to be examined, corresponding to the refractive power of the eye to be examined.

(Problems to be Solved by the Invention) However, in this conventional fixation chart projection system, the astigmatic power of the subject's eye is not corrected, but it is difficult to accurately measure the subject's eye having a strong astigmatic power. It had the following drawbacks.

In other words, in order to properly create foggy vision in the subject's eye with astigmatic power, the fixation chart must be set so that the refractive power on the strong principal meridian is located at the far point. In the case of a person with astigmatism, the amount of blur on the fixation chart becomes too large, making it difficult to stably gaze at the fixation chart, resulting in a problem that highly accurate measurement results cannot be obtained.

(Purpose of the Invention) The present invention was made with the aim of solving the problems of the prior art, and after once roughly measuring the spherical power, astigmatic axis, and astigmatic power of the eye to be examined, this measurement result is It is an object of the present invention to provide an objective type automatic eye refractive power measurement device that can correct the degree of astigmatism and astigmatism axis of a fixation target based on the above, and measure refractive power with high precision.

(Means for Solving the Problems) The present invention provides an astigmatism system that corrects the degree of astigmatism of the eye to be examined based on the measurement results of the measurement system, in a fixation chart projection system that projects an optic mark onto the fundus of the eye to be examined. A corrective optical system is installed and the measurement system is used to perform precise measurements again.

(Function) According to the present invention, even in a subject with severe astigmatism, the astigmatism is corrected using the astigmatism correction optical system, and then re-measurement is performed to correct the spherical power, astigmatism axis, and astigmatism power. Can be measured accurately.

(Example) Examples 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, and in this embodiment, an eye refractive power measuring device for both subjective and objective vision will be described. In this Figure 1, 1
2 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, 5.6 is an aiming optical system, 7 8 is the eye to be examined, and 8 is the anterior segment of the eye. The target image projection system 1 has a function of projecting target light onto the fundus 9 of the eye 7 to be examined via the shared optical system 3 to form a target image on the fundus 9 . This target image projection system 1 includes one light emitting element 10
．． Condenser lens 11, index plate 12, reflection prism 1
3.14, a relay lens 15, and a reflecting prism 16. The light emitting element 10 has a center wavelength of 880
It emits infrared light of nm wavelength, and this infrared light has the function of converting into a parallel beam of light by the condenser lens 11 and illuminating the index plate 12.

As shown enlarged in FIG. 2, the index plate 12 has slits 12a to 12d formed therein, and four deflection prisms 17 to 20 are attached to the index plate 12. The index plate 12 has a function of forming a measurement target light by being illuminated with infrared light, and includes deflection prisms 17 to 20.
has a function of deflecting the target light in a direction perpendicular to the longitudinal direction of the slit.

The shared optical system 3 includes a half-moon aperture plate 21. slit prism 2
2. It has an image rotator 23 and a beam splitter 25. The target light formed by the index plate 12 is reflected by the reflecting prisms 13, 14, and 16 and guided to the meniscal diaphragm plate 21, where it passes through the meniscus hole 2, which is shown enlarged in FIG.
1a and 21a, is reflected by the reflective surface 22a of the slit prism 22, passes through the pupil of the eye 7 to be examined via the image raw data 23, the objective lens 24, and the beam splitter 25, and is projected onto the fundus 9. It's happening. With respect to the objective lens 24, the half-moon diaphragm 21 is placed conjugate with the pupil position of the subject l'I17, which is in the proper position, so as to avoid reflected light harmful to measurement from the anterior segment of the subject's eye. It has a function of making light enter the eye 7 to be examined. The image raw data 23 is obtained by rotating the fundus 9 at an angle of θ/2 around the optical axis Q of the shared optical system 3.
It has a function of rotating the measurement target image formed in the meridian direction of the subject 0I 29 by θ degrees, and FIG. 4 shows the planar shape of this image raw data 23. The beam splitter 25 has a wavelength of 400 nm.
It reflects 75% of the light within the range from
+) has the characteristic of transmitting 100% of the light. Since this target light is invisible light, miosis due to projection of the target image is prevented.

The reflected light of the measurement target image projected on the fundus 9 is transmitted through the beam splinter 25, the objective lens 24, the slit hole 22a of the slit prism 22, the aperture 26a formed in the center of the aperture diaphragm plate 26 (see FIG. 5), The light is guided to the imaging optical system 2 via a relay lens 27 and a reflecting prism 28. The aperture diaphragm plate 26 is connected to the eye 7 to be examined.
The relay lens 27 has a function of guiding reflected light passing through the center of the pupil to the relay lens 27. The imaging optical system 2 includes a reflecting mirror 29, a fixed sunspot plate 30, and a moving lens 3.
1, a reflecting mirror 32, a perforated mirror 34, and an imaging lens 3
5, and has a function of guiding the reflected light of the measurement target image formed on the fundus 9 to the photocathode 36a of the imaging device 36 and forming the measurement target image on the photocathode 36a. . Here, image raw data 2
3, when it is rotated by θ/2 degrees around the optical axis Q,
The measurement target image is rotated by 0 degrees in the rotation direction, but since the reflected light of the measurement target image reflected at the fundus 9 passes through the image raw data 23 again, the rotation direction of the image raw data 23 and The measurement target image is rotated by θ degrees in the opposite direction, and the measurement target image is formed on the photocathode 36a of the imaging device 36 facing in a predetermined direction regardless of whether or not the image raw data 23 is rotated. Note that the fixed sunspot plate 30 is provided at a position where the harmful light reflected by the objective lens 24 is focused.
Based on this, reflected light harmful to measurement is removed.

The chart projection system 4 includes a tungsten lamp 37, a color correction filter 3B, a condenser lens 39, a chart disk 50, a collimator lens 41, a moving lens 42, a reflective mirror 43, 44, a relay lens 45, and a reflective mirror. The mirror 46 and the objective lens 47 are generally configured.

The chart disc 50 is provided with a fixation chart board 51 and various chart boards 52 for subjective optometry, and by rotating the chart disc 50, a desired chart board can be inserted into the optical path. ing. The chart board inserted into the optical path is illuminated by a tungsten lamp 37 via a condenser lens 39 and a color correction filter 38. The wavelength of the light emitted from the tungsten lamp 37 is selected by a color correction filter 38, and the color correction filter 38 transmits visible light having a wavelength of 400 nm to 70 On+s. This fixation chart board 51 is provided with an equal rights chart 51a as shown in FIG. The direction is changed by .46, and the objective lens 47
The beam passes through the beam splitter 48 and is guided to the beam splitter 48. This beam splitter 48 has a characteristic of reflecting 75% of light with wavelengths in the visible light range, and the fixation chart light is reflected by this beam splitter 48 toward the beam splitter 25, and is reflected by the beam splitter 25. and is guided to the eye 7 to be examined. When performing objective measurement to automatically measure the refractive power of the subject's eye 7, the subject fixes his or her eye on the equivalence chart 51a.

Further, when performing a subjective measurement, for example, as shown in FIG. 7, a chart board 52 for subjective optometry having a blind ring 52a and the like is inserted into the optical path. The chart disc 50 is provided with a large number of chart boards 52 for subjective optometry having charts of various patterns and sizes.
Selectively select the desired chart board 52 by rotating the
is inserted into the optical path and visually inspected by the examiner. In FIG. 1, reference numeral 53 denotes a cylindrical lens optical system, which is arranged at a substantially conjugate position with the eyeglass wearing position of the eye 7 to be examined. This cylindrical lens optical system 53 will be described later. The movable lens 42 is disposed so as to be movable in its forward axis direction, and when performing objective measurement, it is set at a position that makes the eye 7 to be examined look foggy in accordance with the refractive power of the eye 7 to be examined. Objective measurement can be performed with the accommodative power of the optometrist 7 removed. In the case of subjective measurement, the movable lens 42 is moved in response to the test subject's response, and the refractive power of the test subject's eye can be measured from the amount of movement.

The aiming optical system 5 includes an infrared light source 54 that emits infrared light as invisible light having a center wavelength of 80On+a, and a projection lens 55.
and a perforated mirror 56, this infrared light passes through the perforated mirror 56 and the beam splitter 48, is reflected by the beam splitter 25, and is projected onto the cornea 7a. ing. Optical axis Q of shared lens optical system 3
When coincides with the corneal vertex ○.

A bright spot image of the infrared light emitted from the infrared light source 54 is formed at the corneal apex ○, thereby adjusting the alignment of the optical system with respect to the eye 7 to be examined.

The infrared light forming this bright point image is reflected at the corneal vertex at O, is reflected by the beam splitter 25, passes through the beam splitter 48, is redirected by the six-bright mirror 56, and is guided to the objective lens 57. The light is reflected by the perforated mirror 34, guided to the imaging lens 35, and imaged on the photocathode 36a of the imaging device 36 as a bright spot image. Note that since this infrared light is also invisible light, miosis of the eye 7 to be examined is prevented.

The aiming optical system 6 includes an infrared light source 58 that emits infrared light with a wavelength of 700 nm, a diffuser plate 59', and a scale plate 60'.
A circular through hole 60'a is formed in the scale plate 60', and the infrared light passing through the circular through hole 60'a is converted into scale image projection light. It is what it is. This scale image projection light is reflected by the beam splitter 48 and the perforated mirror 56, guided to the objective lens 57, and reflected by the perforated mirror 34.
The light is guided to an imaging lens 35, and is imaged by the imaging lens 35 on a photocathode 36a of an imaging device 36 as a circular scale image. Note that the beam splitter 48 has a function of reflecting about 50% of this scale image.

The anterior segment 8 is illuminated by illumination lamps 62', 62', and the wavelength of the illumination light emitted from these illumination lamps 62', 62' is set to 800nw, which is different from the wavelength of the target light. are considered to be different. The reason for this will be described later. Since this illumination light is also invisible light, miosis of the subject's eye 7 due to the illumination light is prevented. The anterior segment illumination light reflected at the anterior segment 8 is
It is reflected by the beam splitter 25, passes through the beam splitter 48, is reflected by the perforated mirror 56.34, and is guided to the imaging lens 35. The reflection path of the bright point image formed as a partial image and reflected at the corneal apex 0 and the reflection system path of the illumination light reflected at the anterior segment 8 are the same, and the scale image projection path and its anterior segment The reflection path of the illumination light reflected at 8 shares the same optical axis.

The imaging device 36 is connected to a television monitor 58, and 59 is its display surface. The image formed on the photocathode 36a is displayed on the display surface 59 based on the video signal from the imaging device 36. In FIG. 1, 60 is an anterior segment image, 62 is a circular scale image, 63 is a bright spot image, and 64 is a measurement target image.

The measurer can adjust the alignment of the optical system while checking the positional relationship between the anterior segment image 60, the circular scale image 62, and the bright spot image 63 displayed on the display surface 59.

When the target image 64 is in focus at the eye/fundus 9, as shown in FIG.
The interval 111 of the lower pair of target images 64b coincides with the interval 111 of the lower pair of target images 64b, and when the target image 64 is not focused on the fundus 9, the interval Q] and the interval 112
For example, when the measurement target image is focused in front of the fundus 9, the interval Or becomes smaller than the interval α2 as shown in FIG.
When the measurement target image is focused behind the fundus 9,
As shown in FIG. 11, the interval 111 is larger than the interval. During objective measurement of refractive power, the index plate 12 is moved so that the intervals (It, (lz) of the set target images 64 are matched.

The eye refractive power is determined by the amount of movement of the index plate 12 until the distance α1 and the distance aZ match. At this time, the movable lens 31 is driven so as to maintain a conjugate relationship with the index plate 12.

In the imaging optical system 2, a five-wavelength selection filter 65 is provided between the imaging lens 35 and the imaging device 36 so as to face the photocathode 36a of the imaging device 36. This wavelength selection filter 65 contains light with a wavelength of 800 nn+ and light with a wavelength of 880 nn+.
A transparent glass plate that transmits nm light is used.
As shown in FIG. 11, a wavelength-selective vapor deposited film 65a that transmits light with a wavelength of 880 nm but blocks light with a wavelength of 800 nm is provided on the half side of the center where the target image is formed. ing. According to this wavelength selection filter 65, the light forming the peripheral part of the anterior eye segment image 60 is blocked by the wavelength selective vapor deposition $65a, so that the anterior eye segment a60 is projected onto the measurement target image 64 in an overlapping manner. This prevents the anterior segment image 60 and the measurement target image 64 from overlapping.

Note that the six-bright mirror 34 has a function of focusing the reflected light that forms the anterior segment image on one side of the photocathode 36a and forming an image thereon.

Next, a refractive power measurement circuit for objective measurement will be explained.

In FIG. 12, the refractive power measurement circuit includes a CPU 66,
The CPU 66 includes a printer circuit 68, a drive circuit 69 . Signal detection circuit 67
, and has a function of controlling the television monitor 58, and the control mode can be switched between subjective measurement and objective measurement using a measurement mode changeover switch 70. The signal detection circuit 67 is generally composed of a target image signal detection circuit 71 , a delay circuit 72 , a reference signal formation circuit 73 , a timing signal formation circuit 74 , and a target image position detection circuit 75 . Based on the output of the CPU 66, the drive circuit 69
It is configured to drive and control the Drive circuit 69
a first drive control section 69a for driving the index plate 12 and the moving lens 31 along the optical axis; a second drive control section 69b for rotationally driving the image raw data 23 around the optical axis; It is composed of a third drive control section 69c for driving the moving lens 41 of the chart projection system 4 along the optical axis, and a fourth drive control section 69d for driving the cylindrical lens optical system 13 of the chart projection thread 4. , this driving result is CP
The information is fed back to U66, and CPU66 performs calculations based on this information and outputs the measured value to printer circuit 68.

Next, the operation of the eye refractive power measuring device according to the present invention will be explained with reference to the flowchart shown in FIG. 13 in cases where objective measurement and subjective measurement are performed. It is assumed that the anterior segment image 60 and the measurement target @64 are displayed on the first display surface 59 at the same time.

When performing objective measurement, the CPU 66 first performs step 10.
Initial value setting processing is performed at 0. Through this initial setting process, the index plate 12 is placed at the zero diopter position. In addition, the image raw data 23 is rotated around the optical axis, and as shown in FIG. and the angle θ is 45 degrees (this is called the 45 degree meridian). Further, the movable lens 42 is moved so that the subject can visually recognize the equivalence chart at the zero diopter position. Further, the cylindrical lens optical system 53 is set to zero diopter. Next, the measurement mode changeover switch 70 is switched to the objective measurement mode, and the measurement mode switch is turned on. Then, in step 101, a process for determining whether the objective measurement mode switch is on is performed. If the objective measurement mode switch is on, step 10
In step 2, a process for detecting the interval (11, C10) between the measurement target images is performed.Next, in step 103, a process for determining whether this interval difference 1ux-121 is smaller than a predetermined value ε is performed.Interval difference IL-121 is larger than the predetermined value ε, one interval difference 1 (11
- [Indicator plate 1 in the direction where L21 is smaller than the predetermined value E.
Drive 2. At that time, the movable lens 31
is also moved to maintain the conjugate relationship between the index plate 12 and the photocathode 36a. These steps 102, 103 and 104 are repeated until the interval % l ax - α21 - ε is reached. Along with this movement of the index plate 12, the third drive control section 69c moves the movable lens 42 to maintain a foggy state for the subject.

Since both the anterior segment image 60 and the measurement target image 64 are displayed on the display surface of the display device 58, the examiner can see under what conditions the measurement is being performed.

When the slit interval difference l (it (L2 l) becomes t, a process of reading the position of the measurement target image is performed in step 105. Next, a process of reading the interval difference IL-1121 value (step 106) is performed. This target image Based on the data obtained by the position reading process (step 105) and the interval difference 1!11-o, zl value reading process (step 106), the CPU 6
6 performs calculation processing of refractive power (step 109).

As a result, the refractive power in the 45-degree meridian direction is determined.

Here, before performing the process of step 109, the image raw data 23 is rotated every 30 degrees (step 108), the measurement target image is rotated every 60 degrees,
The refractive powers for the three meridians are determined and processed (step 107). In Figure 14,
r and s I+ indicate the direction perpendicular to the longitudinal direction of the slit when the measurement target image is rotated by 60 degrees.

Here, if the eye 9 to be examined has astigmatism, the measurement target image is detected separately as the image raw data 23 is rotated. At that time, if the image raw data 23 is rotated around the optical axis, the refractive power Do in the meridian angle O direction is the diopter value De at the movement stop position of the index plate 12 and the diopter value ΔDo corresponding to the slit separation amount. It is known that there is a relational expression described below between the spherical power A, the astigmatic power B, and the astigmatic axis angle α.

Since Da=A+Bcos (θ−α), the refractive power in the three meridian directions is D81°D112.
If Doco can be obtained by measurement, Dllll:
A+BCO52(θ1-α)Do = =A0Bcos
2 (θ2−α)DI! 3 =A+BCO82(0*
-α), the spherical power A, the astigmatic power B, and the astigmatic axis angle α can be obtained.

The main measurement is performed based on the calculation results of the spherical power A, the astigmatic power B, and the astigmatic axis angle α obtained in this way.

In this measurement, the meridian direction is divided into small sections, for example, 15 meridians. In this actual measurement, a one-cylindrical lens optical system 53 is used. This cylindrical lens optical system 53 consists of a cylindrical lens 53a and a cylindrical lens 53b. When the pair of lenses 53a and 53b are rotated together at an equal angle in the circumferential direction, the astigmatic axis is corrected, and the two lenses 53a , 53
Astigmatism is corrected by rotating the lenses b by equal angles in opposite directions. This cylindrical lens optical system 53 is driven and controlled based on the calculation results of the astigmatic power B and the astigmatic axis angle α, and is set so that the subject's fixation chart can be fixed uniformly (step 110). Next, the movable lens 42 is moved by the third drive control unit 69c to a position where the fog state is maintained for the subject (step 111).In steps 110 and 111, the fixation chart is adjusted to the refractive power of the subject's eye. With corresponding settings, the subject can fixate the fixation chart uniformly and with proper fog.

Next, rotate the image raw data 23 every 6 degrees,
The measurement target image is rotated every 12 degrees, and the refractive powers Dei to Da15 for the 15 meridians are measured (steps 112 to 115). This refractive power DI11
~D@15, the spherical power A, astigmatic power B, and astigmatic axis angle α are calculated by the least squares method, and the calculation results are displayed on the display screen (step 116). This measurement corrects astigmatism when the subject's eye 7 has astigmatism, so it uses a fixation chart as a standard, and it is possible to obtain accurate measurement results that do not affect the subject's eye 7, which has astigmatism. Become. next,
In step 117, it is determined whether or not to repeat the measurement, and if necessary, repeat the steps 110 to 110.
16 measurements are taken and the final measurements are printed out (step 118).

Next, the case of performing subjective measurement will be explained.

In the case of subjective measurement, the moving lens 41 is moved in the optical axis direction of the chart projection system 4 based on the spherical power A of the eye 7 to be examined, and its moving position is set.

Furthermore, the astigmatic power B is corrected by the one-cylindrical lens optical system 53. In this state, the chart disc 50 is rotated and a desired chart board 52 for subjective optometry is inserted into the optical path. That is, in the subjective measurement, the subjective optometry chart board 52 is visually recognized with the refractive power obtained in the objective measurement corrected.

The subjective measurement is performed by having the subject visually recognize the chart board 52 for subjective optometry. The examiner corrects the spherical power by driving the movable lens 42 and corrects the astigmatic axis and astigmatic power by driving the cylindrical lens optical system 13 according to the test subject's response. This drive amount is input to the CPυ66, and the measurement results are printed out as measured values in steps 120 and 121. A measurement target image, which is invisible light, is projected onto the fundus of the subject's eye onto the subjective measurement medium, superimposed on the subjective optometry chart image. At this time, the index plate 12 is always driven to a position corresponding to the correction power in the chart projection system. At that time, the examiner
The target image 64 displayed on the display surface 59 of the television monitor 58 is the visible image I! Since it is possible to perform subjective measurement while observing the chart image, it is possible to easily know in what state the subject is undergoing the examination while visually recognizing the chart image.

In the above embodiments, an eye refractive power measuring device for both subjective and objective purposes has been described, but the present invention can also be applied to a subjective eye refractive power measuring device.

(Effects of the Invention) According to the present invention, even a subject with severe astigmatism can be made to gaze at the fixation chart in an appropriately stable state,
Refractive power can be measured with high precision even when no accommodating force is applied.6

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing the optical system of the eye refractive power measuring device according to the present invention, FIG. 2 is an enlarged perspective view showing the detailed configuration of the index plate shown in FIG. 1, and FIG. Fig. 4 is an enlarged plan view showing the outline shape of the image raw data shown in Fig. 1; Fig. 5 is an enlarged plan view showing the shape of the half-moon diaphragm shown in Fig. 1; Fig. 5 is an enlarged plan view showing the shape of the half-moon diaphragm shown in Fig. 1. FIG. 6 is an enlarged plan view of the fixation chart board shown in FIG.
FIG. 7 is a plan view showing the shape of a chart board for subjective optometry used in the eye refractive power measuring device according to the present invention, and FIGS. 8 to 1O are images of the measurement target image shown in FIG. 1. 11 is an enlarged plan view of the wavelength selection filter shown in FIG. 1; FIG. 12 is a block diagram of a measuring circuit used in the eye refractive power measuring device according to the present invention; FIG. 13 is a plan view showing the state;
The figure is a flowchart for explaining the measurement procedure of the refractive power greenhouse device of the ophthalmological instrument according to the present invention, and FIG. 14 is an explanatory diagram for explaining the measurement procedure. DESCRIPTION OF SYMBOLS 1... Target image projection system, 2... Imaging optical system, 3... Shared optical system, 4...
...Chart projection system, 5.6...Sighting optical system. 7... Eye to be examined, 8... Anterior segment, 9... Fundus, lO... Light emitting element, 36... Imaging device,
36a...Photocathode. 58...TV monitor, 59...Display surface, 62'
...Illumination lamp, 65...Wavelength selection filter. 65a, . . . wavelength selective transmission section, 66 . . . CPU; Figure 2 Figure 3 Figure 1F Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 J2 Figure 11 Figure 12

Claims (1)

[Claims] A measurement system that projects a measurement target image onto the fundus of the eye to be examined, photoelectrically detects the in-focus state of this measurement target image, and measures the refractive power of the eye to be examined, and a fixation chart that projects the fixation chart onto the eye to be examined. In the objective automatic eye refractive power measuring device having a projection system, the fixation chart projection system is provided with an astigmatism correction optical system for correcting the degree of astigmatism of the eye to be examined based on the measurement results of the measurement system, and the measurement optical system is An objective type automatic eye refractive power measuring device characterized by performing precise measurements using a system.