JPS61164541A - Eye refractive force measuring apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention projects an optometric chart image onto the fundus of the eye to be examined using visible light, and adjusts the refractive power of the eye to be examined based on the response of the examinee. The present invention relates to an eye refractive power measurement device.

(Prior art) Conventionally, in an eye refractive power measurement device that measures the refractive power of the eye to be examined, the examinee is asked to look at an optometry chart, and depending on the examinee's responses, the corrective lens is inserted until the chart looks appropriate. A so-called subjective type method is known in which the refractive power of the eye to be examined is measured using the dioptric power of the corrective lens. Also,
Project a measurement target image onto the eye to be examined using invisible light,
This type of subjective refractive power measuring device is incorporated into the so-called objective type, which objectively measures the refractive power of the eye to be examined by photoelectrically detecting the focused state of the target image. An eye refractive power measuring device that can also be used as an objective eye is also known.

(Problems to be solved by the invention) However, in any eye refractive power measuring device,
During subjective ophthalmoscopy, the examiner cannot see if the ophthalmometric chart image projected onto the fundus of the examinee's eye. Inspections had to be carried out while determining whether or not they were present, and many years of experience were required to make accurate measurements.

(Object of the Invention) The present invention has been made in consideration of the above circumstances, and its purpose is to project a chart image for subjective optometry onto the fundus of the eye to be examined using visible light. At the same time, in order to make it easier to judge in what state the patient is viewing the chart, a target image is projected using invisible light separately from the subjective optometry chart image, and this target image is converted into a visible image. An object of the present invention is to provide an eye refractive power measuring device that can be converted and observed with the naked eye.

(Means for Solving the Problems) The present invention projects a chart image for subjective optometry onto the fundus of the eye to be examined using visible light, and measures the refractive power of the eye to be examined based on the response of the examinee. In an eye refractive power measurement device, an invisible light target image projection system that projects a chart image for subjective optometry and an invisible light target image onto the fundus of the eye to be examined, and a display unit that displays the target image as a visible image. An eye refractive power measuring device characterized by comprising:

(Function) According to the configuration of the present invention, a target image of invisible light is projected onto the fundus of the eye to be examined at the same time as the chart image for subjective ophthalmoscopy is projected, and the target image formed on the fundus of the eye to be examined is displayed on the display. This target image allows the refractive state of the eye to be examined during subjective eye examination to be known.

(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 used by target image projection system 1 and imaging optical system 2, 4 is a chart projection system, 5 and 6 are aiming optical systems, 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, reflective prism 1
3.14, a relay lens 15, and a reflecting prism 16. The light emitting element 10 has a center wavelength of IHL.
It emits infrared light of Onm, and this infrared light is converted into a parallel light beam by a condenser lens 11 and sent to an index plate 12.
It has the function of illuminating.

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. Image rotator 23. It has 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, 21a, is reflected by the reflective surface 22a of the slit prism 22, and is converted into image raw data 23. The light is projected onto the fundus 9 through the pupil of the eye 7 via the objective lens 24 and beam splitter 25. The half-moon diaphragm plate 21 is arranged in a conjugate position with respect to the objective lens 24 and the pupil position of the subject's eye 7, which is in the proper position, and directs the target light without causing reflected light harmful to measurement from the anterior segment of the subject's eye. It has a function of making the light enter the eye 7 to be examined. The image rotator 23 has the function of rotating the measurement target image formed on the fundus 9 by θ degrees in the meridian direction of the eye 9 by rotating the optical axis Q of the shared optical system 3 by 072 degrees. FIG. 4 shows the planar shape of this image rotator 23.

The beam splitter 25 has a wavelength of 400 nm or 6700 nm.
Reflects 75% of light within the range of up to 75 nm.
It has the property of reflecting 50% of light in the range of 0 nm to 820 nm and transmitting 100% of target light (wavelength of 880 nm). 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 to the beam splitter 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 5th @), The light is guided to the imaging optical system 2 via a relay lens 271 and a reflecting prism 28. The aperture diaphragm plate 26
The relay lens 27 has a function of guiding reflected light passing through the center of the vagina 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 rotator 2
3, when it is rotated by θ12 degrees around the optical axis Ω,
The measurement target image is rotated by θ degree in the rotation direction, but since the reflected light of the measurement target image reflected at the fundus 9 passes through the image rotator 23 again, the rotation direction is opposite to the rotation direction of the image rotator 23. The measurement target image is rotated by θ degrees in the direction, and the measurement target image is formed on the photocathode 36a of the imaging device w36 facing in a predetermined direction regardless of whether or not the image rotator 23 is rotated. The fixed sunspot plate 30 is provided at a position where harmful light reflected by the objective lens 24 is focused, and based on this, reflected light harmful to measurement is removed.

The chart projection system 4 includes a tungsten lamp 37, a color correction filter 38, a condenser lens 39, a chart disk 50, a collimator lens 41, a moving lens 42, reflective mirrors 43, 44, a relay lens 45, and a reflective mirror. It is roughly composed of a mirror 46 and an objective lens 47.

The chart disc 50 is provided with a fixation chart board 51 and various optometry chart boards 52, and by rotating the chart disc 50, a desired chart board can be inserted into the optical path. It has become. 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 3B. 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 700 nm. The fixation chart board 51 is provided with an equal rights chart 51a as shown in FIG.
3,44,46, the beam passes through an objective lens 47, and is guided to a beam splitter 48. This beam splitter 48 has a characteristic of reflecting 75% of light with a wavelength in the visible light range, and the fixation chart light is reflected by this beam splitter 4B 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 eye 7 to be examined,
The subject performs the examination by fixating his/her eyes on the equivalence chart 51a.

Further, when performing subjective measurement, a chart board 52 for subjective optometry having a Landolt ring 52a and the like is inserted into the optical path, as shown in FIG. 7, for example. The chart disc 50 is provided with a large number of chart boards 52 for subjective optometry having charts of various patterns and sizes, and by rotating the chart disc 50, a desired chart board 52 can be selectively inserted into the optical path. The eye is then visually checked by the examiner. 1st
In the figure, 53 is a cylindrical lens optical system, and the subject's eye 7
The lens is located at a position approximately conjugate to the glasses-wearing position. This cylindrical lens optical system 53 will be described later. moving lens 4
2 is disposed so as to be movable in the direction of its optical axis, and during 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 adjustment force 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 invisible infrared light with a center wavelength of 800 nm, a projection lens 55, and a perforated mirror 56. Mirror 56. It passes through the beam splitter 48, is reflected by the beam splitter 25, and is projected onto the angle jl[7a. When the optical axis a of the shared lens optical system 3 coincides with the corneal apex O, a bright spot image of the infrared light emitted from the infrared light g54 is formed at the corneal apex O. This is for adjusting the alignment of the optical system for the optometry 7. The infrared light forming this bright spot image is reflected at the corneal vertex at 0, is reflected by the beam splitter 25, passes through the beam splitter 48, is redirected by the perforated mirror 56, and is guided to the objective lens 57. The light is reflected by the perforated mirror 34 and guided to the imaging lens 35, where it is reflected by the photocathode 36a of the imaging device 36.
It is imaged 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'.
and a projection lens 61'.

A circular hole 60'a is formed in the scale plate 60', and infrared light passing through the circular hole 60'a becomes scale image projection light. This scale image projection light is reflected by the beam splitter 48 and the perforated mirror 56, guided to the objective lens 57, reflected by the perforated mirror 34, and guided to the imaging lens 35. An image is formed on the photocathode 36a of the imaging device 3G as a circular scale image. Note that the beam splitter 4B 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 the illumination lamps 62', 62' is set to 800 nm, 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 the display surface 59 displays an image formed on the photocathode 36a based on the video signal from the imaging device 36. be done. 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 listener 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 on the fundus 9, as shown in FIG.
a distance q1 and the distance 1z between the lower pair of target images 64b
match, and the target image 6 in the fundus 9
4 is out of focus, the interval q1 is different from the interval Lz. For example, when the measurement target image is focused in front of the fundus 9, the interval q1 is the interval Lz, as shown in FIG. Also, when the m constant target image is focused behind the fundus 9, the 11th
As shown in the figure, the interval q1 is larger than the interval ILz.

During objective measurement of refractive power, the index plate 12 is moved so that the distance Qx and a2 between the measurement target images 64 match, and the index board 12 is moved until the distance q1 matches the distance. The eye refractive power is determined by the amount of movement when the lens moves. 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 wavelength selection filter 65 is provided between the imaging lens 35 and the imaging device 136 so as to face the photocathode 36a of the imaging device w136. This wavelength selection filter 65 contains light with a wavelength of 800 nm and light with a wavelength of 88 nm.
A transparent glass plate that transmits 0na+ light is used, and as shown in Figure 11, it transmits light with a wavelength of 880 nm to the half of the center where the target image is formed. A wavelength-selective deposited film 65a is provided that blocks light of 800 nm. 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 deposited film 65a, so that the anterior eye segment image 60 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 perforated mirror 34 has a function of focusing the reflected light forming the anterior ocular segment image on one side of the photocathode 36a.

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, and a 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 the constant 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 60a 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 system 4. , this driving result is CP
The information is fed back to U 66 , and CPU 66 performs calculations based on this information and outputs the estimated 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 eye segment image 60 and the measurement target image 64 are displayed on the first display surface 59 at the same time.

In the event of an objective concubine, the CUP 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 α, and as shown in FIG. The angle θ is set to be 45 degrees (this is referred to as 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, switch the measurement mode changeover switch 70 to the objective measurement mode, and 8I! Turn on the constant mode switch. Then, in step 101, a process for determining whether the objective measurement mode switch is on is performed. When the objective measurement mode switch is on, in step 102, the interval (h, ILz) of the measurement target images is detected.Next, in step 103, it is determined whether this interval difference 1α1-kl is smaller than a predetermined value ε. If the 0 interval difference JChlLzl, which is used to determine whether or not
The index plate 12 is driven in a direction in which kl becomes smaller than a predetermined value ε. At this time, the movable lens 31 is also moved together with this, and the conjugate relationship between the index plate 12 and the photocathode 36a is maintained. Steps 102, 103 and 104 are repeated until the interval difference IQI-1121<ε. This index plate 12
As the subject moves, the third drive control unit 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 observe under what conditions the measurement is being performed.

When the slit interval difference 1 (h-kI <E), the position of the measurement target image is read in step 105. Next, the interval difference 1tlt-1121 value is read (step 106). This target image position reading process (step 105) and interval difference 1
Based on the fhail value reading process (step 106) and the data obtained, the CPU 66 performs refractive power calculation process (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 power for the three meridians is calculated and processed (step 107).
', s'' indicate a 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 DI+ in the meridian angle θ direction is the diopter value Dθ at the movement stop position of the indicator plate 12 and the diopter value ΔD9 corresponding to the slit separation amount. expressed as the sum of 1 spherical power A
It is known that there is a relational expression described below between the astigmatic power B and the astigmatic axis angle α.

Since D9=A+Bcos (θ−α), the refractive power in the three meridian directions is D81°Da2. D
If ea can be obtained by measurement, Da 1=A+
Bcos2 (θ1−α)De 2 ==A+Bcos
2 (θ2-α)Da :s = A+Bcos2 (θ
Based on the equation 3-α), the spherical power A, the astigmatic power B, and the astigmatic axis angle α can be obtained.

Two measurements are 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 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. Correspondingly set, the subject can fixate the visual 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 power Dsx to Do1s for the 15 meridians is measured (steps 112 to 115).
~Dos, the spherical power A, the astigmatic power B, and the 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 is performed on the eye to be examined.
Since the astigmatism is corrected when there is astigmatism in the subject's eye 7, the fixation chart is used as a standard and an accurate measurement result is obtained in which no accommodative force is applied to the eye 7 having astigmatism.

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.

Moreover, the astigmatic power B is corrected by the 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 CPU 66.

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 subjective measurement medium and 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 can perform subjective measurements while observing the target image 64 displayed on the display surface 59 of the television monitor 58 as a visible image, so the examiner can perform subjective measurements while observing the target image 64 displayed on the display surface 59 of the television monitor 58. You can easily know whether you are undergoing an inspection while visually checking the information.

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 when performing a subjective eye examination, by observing the state of the target image formed in the fundus of the eye to be examined as a visible image, the patient can It is possible to easily determine whether the chart image is standard based on the condition, and accurate eye examination can be performed.

Furthermore, since the target image projected separately from the chart image for subjective optometry uses invisible light, the target image can be observed without affecting the subjective optometry. Furthermore, the chart image for subjective optometry that is projected onto the subject's eye is extremely small, and it is extremely difficult to detect the chart image itself. It is possible to project a target image of any size and any shape, and has the effect that wA detection can be performed extremely easily.

[Brief explanation of drawings]

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 10 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 measuring device for an ophthalmological instrument according to the present invention, and FIG. 14 is an explanatory diagram for explaining the measurement procedure. l... Target image projection system, 2... Imaging optical system, 3... Shared optical system, 4...
・Chart projection system, 5, 6... Aiming optical system, 7...
Eye to be examined, 8...Anterior segment. 9... fundus, 10... light emitting element, 36...
- Imaging device, 36a... Photocathode, 58... Television monitor, 59... Display surface, 62'... Illumination lamp,
65...Wavelength selection filter, 65a...Wavelength selection transmission section, 66...cpu. Fig. 2 Fig. 3 Fig. 4 Fig. 5171 Fig. 6 @ Fig. 7 Fig. 8 Fig. 9 Fig. 10 Fig. 11 Fig. 12

Claims (1)

[Scope of Claims] An eye refractive power measurement device that projects a chart image for subjective optometry onto the fundus of the eye to be examined using visible light, and measures the refractive power of the eye to be examined based on the responses of the eye, comprising: It is characterized by comprising an invisible light target image projection system that projects an invisible light target image onto the fundus of the eye to be examined simultaneously with the projection of the ophthalmoscopy chart image, and a display section that displays the target image as a visible image. An eye refractive power measurement device.