JPH0439332B2 - - Google Patents

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention projects a chart image for optometry 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 measuring device that measures the refractive power of the eye to be examined, the examinee is asked to look at an optometry chart, and the corrective lens is inserted until the chart looks appropriate based on the examinee's responses. A so-called subjective type method is known in which the refractive power of the eye to be examined is measured using the power of the corrective lens. In addition, we have developed a so-called objective method that objectively measures the refractive power of the eye by projecting a target image onto the patient's eye using invisible light and photoelectrically detecting the focused state of this target image. There is also known an ocular refractive power measuring device for both subjective and objective vision incorporating this type of subjective refractive power measuring device.

(Problems to be Solved by the Invention) However, with any of the eye refractive power measurement devices, during subjective eye examination, the examiner cannot observe the eye examination chart image projected onto the fundus of the eye to be examined. First, the test must proceed while determining whether or not the test subject is looking at the chart based on the responses between the test subject and the examiner. It required experience.

(Objective of the Invention) The present invention has been made in consideration of the above circumstances, and its purpose is to simultaneously project a chart image for subjective optometry onto the fundus of the eye to be examined using visible light; In order to make it easier to judge in what condition the patient is viewing the chart image, 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 allows observation 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 an invisible light target image onto the fundus of the eye to be examined simultaneously with the projection of a chart image for subjective optometry, and a display 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 section. 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 FIG. 1, 1 is a target image projection system, 2 is a target image projection system;
3 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 and 6 are aiming optical systems, 7 is an 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. The target image projection system 1 is generally composed of a light emitting element 10, a condenser lens 11, an index plate 12, reflection prisms 13, 14, a relay lens 15, and a reflection prism 16. The light emitting element 10 emits infrared light with a center wavelength of 880 nm, and this infrared light is converted into a parallel light beam by the condenser lens 11 and has a function of illuminating the index plate 12. The indicator plate 12 has slits 12a to 12d as shown in an enlarged view in FIG.
is formed, and four deflection prisms 17 to 20 are attached to this index plate 12. The index plate 12 has a function of forming measurement target light by being illuminated with infrared light, and the index plate 12 has a function of forming measurement target light by being illuminated with infrared light.
Numerals 7 to 20 have the 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 diaphragm plate 21, a slit prism 22, an image rotator 23, and a beam splitter 25. The target light formed by the index plate 12 passes through the reflecting prisms 13 and 1.
4 and 16 and guided to the semilunar diaphragm plate 21, the semilunar holes 21a and 21a are shown enlarged in FIG.
through the reflective surface 22 of the slit prism 22.
a, and is projected onto the fundus 9 through the pupil of the eye 7 to be examined via the image rotator 23, objective lens 24, and beam splitter 25. The half-moon diaphragm plate 21 is arranged conjugately with the pupil position of the subject's eye 7, which is in an appropriate position, with respect to the objective lens 24, 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 rotates the measurement target image formed on the fundus 9 by θ degrees in the meridian direction of the eye 9 by rotating it by θ/2 around the optical axis l of the shared optical system 3. FIG. 4 shows the planar shape of this image rotator 23. The beam splitter 25 is
Light with a wavelength within the range of 400nm to 700nm
It reflects 75% and inverts 50% of the light whose wavelength is in the range of 750nm to 820nm, and converts the target light (wavelength
It has the property of transmitting 100% of wavelength (880nm). 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 and the objective lens 2.
4, slit hole 22a of slit prism 22,
Aperture 26 formed in the center of aperture diaphragm plate 26
a (see FIG. 5), is guided to the imaging optical system 2 via a relay lens 27 and a reflecting prism 28. The aperture diaphragm plate 26 is arranged at a position conjugate with the pupil of the eye 7 to be examined, and 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, a movable lens 31, a reflecting mirror 32, and a perforated mirror 3.
4 and an imaging lens 35, the fundus 9
It has a function of guiding the reflected light of the measurement target image formed in the image pickup device 36 to the photocathode 36a of the imaging device 36, and forming the measurement target image on the photocathode 36a. Here, the image rotator 23
When it is rotated by θ/2 degrees around the optical axis l, the measurement target image will be rotated by θ degrees in the rotation direction, but the reflected light of the measurement target image reflected at the fundus 9 will be reflected again in this direction. In order to pass through the image rotator 23, the measurement target image is rotated by θ degrees in the opposite direction to the rotation direction of the image rotator 23, and the measurement target image is displayed on the photocathode 36a of the imaging device 36 regardless of whether or not the image rotator 23 is rotated. An image is formed facing in a predetermined direction. Note that the fixed sunspot plate 30 is attached to the objective lens 2.
4 is provided at a position where the harmful light reflected at 4 is focused, and based on this, the reflected light harmful to the measurement is removed.

The chart projection system 4 includes a tungsten lamp 37
, color correction filter 38 , and condenser lens 39
, a chart disk 50 , and a collimator lens 41
, a moving lens 42 , and reflecting mirrors 43 and 44
, a relay lens 45 , a reflecting mirror 46 , and an objective lens 47 . The chart disc 50 is provided with a fixation chart board 51 and various charts for subjective optometry 52, and by rotating the chart disc 50, a desired chart board can be inserted into the optical path circle. ing. The chart board inserted into the optical path circle 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 700 nm. This fixation chart plate 51 is provided with a fixation chart 51a as shown in FIG. , 46, passes through an objective lens 47, and is guided to a beam splitter 48. This beam splitter 48 splits 75% of the visible wavelength light.
It has a reflective property, and the fixation chart light is
The beam is reflected by the beam splitter 48 toward the beam splitter 25, and
The light is reflected by and 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 fixates on the fixation chart 51a. When performing subjective measurement, for example, as shown in FIG. 7, a chart plate 52 for subjective optometry having a Landolt 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, and by rotating the chart disc 50, a desired chart board 52 can be selectively inserted into the optical path. death,
The eye is examined visually 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 the direction of its optical axis, and during objective measurement, it is set at a position that causes the eye 7 to be examined to have a foggy vision in accordance with the refractive power of the eye 7 to be examined. With the accommodation power of optometry 7 removed,
It is designed to allow objective measurements. 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. The light passes through a mirror 56 and a beam splitter 48, is reflected by a beam splitter 25, and is projected onto the cornea 7a. The optical axis l of the shared lens optical system 3 is the corneal vertex O
, the infrared light source 54 is applied to the corneal vertex O.
A bright spot image of the infrared light emitted from the eye is formed, and this is used to adjust the alignment of the optical system with respect to the eye 7 to be examined. The infrared light forming this bright spot image is reflected at the corneal vertex at O, and is reflected by the beam splitter 25,
After passing through the beam splitter 48, the perforated mirror 5
6 and guided to the objective lens 57, reflected by the perforated mirror 37, 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 is roughly composed of an infrared light source 58 that emits infrared light with a wavelength of 700 nm, a diffuser plate 59', a scale plate 60', and a projection lens 61'. A circular hole 60'a is formed in the hole 60'a, and the infrared light passing through the circular hole 60'a becomes scale image projection light. This scale image projection light is reflected by a beam splitter 48 and a perforated mirror 56, and is reflected by an objective lens 57.
, is reflected by the perforated mirror 34 , and guided to the imaging lens 35 , where the imaging lens 35 forms an image on the photocathode 36 a of the imaging device 36 as a circular scale image. Note that the beam splitter 48 is
It has the 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 800 nm. It is considered to be different from the wavelength. 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 eye illumination light reflected at the anterior eye segment 8 is reflected by the beam splitter 25, passes through the beam splitter 48, is reflected by the perforated mirrors 56 and 34, and is guided to the imaging lens 35. , this imaging lens 3
5, the reflection path of the bright spot image formed on the photocathode 36a of the imaging device 36 as an anterior segment image and reflected at the corneal vertex O is the same as the reflection path of the illumination light reflected at the anterior segment 8. The scale image projection path and the reflection path of the illumination light reflected at the anterior segment 8 have a common optical axis.

The imaging device 36 is connected to a television monitor 58, and 59 is its display surface. Display surface 59
Based on the video signal from the imaging device 36,
The image formed on the photocathode 36a is displayed. 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 uses this display screen 59.
Anterior segment image 60 and circular scale image 62 displayed in
The alignment of the optical system can be adjusted while checking the positional relationship between the bright spot image 63 and the bright spot image 63.

When the target images 64 are in focus on the fundus 9, as shown in FIG. 9, the distance _l1 between the upper pair of target images 64a and the distance _l2 between the lower pair of target images 64b match. Yes, fundus 9
When the target image 64 is not in focus, the interval l ₁ and the interval l ₂ are different. For example, when the measurement target image is focused in front of the fundus 9, as shown in FIG. interval to
When l ₁ becomes smaller than the interval l ₂ and the measurement target image is focused behind the fundus 9, the first
As shown in FIG. 1, the interval l ₁ is larger than the interval l ₂ .
During objective measurement of refractive power, the index plate 12 is moved so that the distances l ₁ and l ₂ of the measurement target images 64 match, and the index plate 12 is moved until the distances l ₁ and l ₂ match. The eye refractive power is determined by the amount of movement when the lens 12 is moved. 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 36 so as to face the photocathode 36a of the imaging device 36. This wavelength selection filter 65 has wavelengths
A transparent glass plate that transmits both 800 nm light and 880 nm wavelength light is used, and as shown in Figure 11, the 880 nm wavelength light is transmitted in the half of the center where the target image is formed. A wavelength-selective vapor deposited film 65a that blocks light with a wavelength of 800 nm that transmits light.
is provided. According to this wavelength selection filter 65, the light forming the peripheral part of the anterior segment image 60 is blocked by the wavelength selection vapor deposited film 65a.
The anterior eye segment image 60 is not projected overlappingly onto the measurement target image 64, and overlapping of the anterior eye segment image 60 and the measurement target image 64 can be prevented. 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 is
66 and a signal detection circuit 67. The CPU 66 has the function of controlling a printer circuit 68, a drive circuit 69, a signal detection circuit 67, and a television monitor 58. The control mode can be switched between subjective measurement and objective measurement. The signal detection circuit 67 includes a target image signal detection circuit 71, a delay circuit 72, and a reference signal formation circuit 73.
The CPU 66 is configured to drive and control the drive circuit 69 based on the output output from the target image position detection circuit 75. There is. The drive circuit 69 includes a first drive control section 69a for driving the index plate 12 and the moving lens 31 along the optical axis, and a second drive control section 69b for rotating the image rotator 23 around the optical axis. , a third drive control section 69c for driving the movable 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 fed back to the CPU 66, which performs calculations based on this information and outputs the measured value to the printer circuit 68.

Next, the function of the eye refractive power measuring device according to the present invention is as follows.
The following describes cases in which objective measurement and subjective measurement are performed with reference to the flowchart shown in FIG. It is assumed that an anterior segment image 60 and a measurement target image 64 are displayed on the display surface 59 at the same time.

When performing objective measurement, the CPU 66 first performs initial value setting processing in step 100. Through this initial setting process, the index plate 12 is placed at the zero deopter position. The image rotator 23 is driven to rotate around the optical axis l, and as shown in FIG. Set so that θ is 45 degrees (this is called the 45 degree meridian). Furthermore, the movable lens 42 is moved so that the subject can visually recognize the fixed finger chart at the zero diopter position. Further, the cylindrical lens optical system 53 is set to a 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. When the objective measurement mode switch is on, in step 102, a process for detecting the distance l ₁ and l ₂ between the measurement target images is performed. Next, in step 103, it is determined whether this interval difference |l ₁ -l ₂ | is smaller than a predetermined value ε. If the interval difference |l ₁ −l ₂ | is larger than the predetermined value ε, in step 104, the interval difference |l ₁
The indicator plate 12 is driven in the direction in which -l ₂ | becomes smaller than the predetermined value ε. At that time, the movable lens 31 is also moved together with this, and the index plate 12 and the photocathode 36a are moved together.
maintains a conjugate relationship with Interval difference | l ₁ − l ₂ | <ε
Repeat steps 102, 103, and 104 until . Along with this movement of the index plate 12, the third drive control section 69c moves the movable lens 42 to maintain the fog state for the subject. Display device 5
Since both the anterior segment image 60 and the measurement target image 64 are displayed on the display screen 8, the examiner can observe under what conditions the measurement is being performed.

When the slit interval difference |l ₁ -l ₂ |<ε, a process for reading the position of the measurement target image is performed in step 105. Next, a process of reading the interval difference |l ₁ −l ₂ | value (step 106) is performed. Based on the data obtained by reading the measurement target image position (step 105) and reading the interval difference |l ₁ -l ₂ | value (step 106), the CPU 66 performs a refractive power calculation process (step
109). As a result, the refractive power in the 45-degree meridian direction is determined. Here, this step
Before processing step 109, image rotator 2
3 is rotated every 30 degrees (step 108), the measurement target image is rotated every 60 degrees, and the refractive power for the three meridians is determined and processed (step 107). In Figure 14, s′,
s'' indicates the direction perpendicular to the longitudinal direction of the slit when the measurement target image is rotated 60 degrees.

Here, if the eye 9 to be examined has astigmatism, the measurement target image is detected separately as the image rotator 23 rotates. At that time, if the image rotator 23 is rotated around the optical axis, the refractive power D in the meridian angle θ direction is
is expressed as the sum of the diopter value D〓 at the movement stop position of the indicator plate 12 and the diopter value ΔD〓 corresponding to the slit separation amount, and the difference between the spherical power A, the astigmatic power B, and the astigmatic axis angle α is , it is known that there is a relational expression explained below.

Since D〓=A+Bcos(θ−α), the refractive power in the three meridian directions is D〓 ₁ , D〓 ₂ , D〓
₃ can be obtained by measurement, then the spherical power can be calculated based on the formula: D〓 ₁ = A + Bcos2 (θ _{1 -} α) D〓 ₂ = A + Bcos2 (θ ₂ - α) D〓 ₃ = A + Bcos2 (θ ₃ - α) A, astigmatic power B, and 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 cylindrical lens optical system 53 is used. This cylindrical lens optical system 53
is composed of a cylindrical lens 53a and a cylindrical lens 53b, and this pair of lenses 53a, 53
By rotating the lenses 53a and 53b integrally at an equal angle in the circumferential direction, the astigmatic axis is corrected, and by rotating the two lenses 53a and 53b at an equal angle in opposite directions, the astigmatic power is corrected. 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 uniformly fixed (step 110). Next, the third drive control section 69c moves the movable lens 42 to a position where the subject is kept in a foggy state (step 111). This, step 110,
111, the fixation chart is set in accordance with the refractive power of the subject's eye, and the subject can fixate the fixation chart uniformly and in an appropriate foggy state. Next, the image rotator 23 is rotated every 6 degrees, the measurement target image is rotated every 12 degrees, and the refractive powers D〓 ₁ to D〓 ₁₅ for the 15 meridians are measured (steps 112 to 115). ). This refractive power D〓 ₁
〜D〓 Based on ₁₅ , calculate the spherical power A by the least squares method,
The astigmatic power B and the astigmatic axis angle α are calculated, and the calculation results are displayed on the display screen (step 116). This measurement corrects astigmatism when the eye 7 to be examined has astigmatism, so the fixation chart is collimated to obtain accurate measurement results that do not affect the eye 7 to be examined which has astigmatism. become. Next, in step 117, it is determined whether or not to perform repeated measurements.
If necessary, the measurements of steps 110-116 are performed again, and the final measured values are printed out (step 118).

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

In the case of subjective measurement, the movable 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. And astigmatism power B is achieved by the cylindrical lens optical system 53.
is corrected. 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 chart board 52 for subjective optometry 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 CPU66
and the measurement results are printed out as measured values in steps 120 and 121. During this subjective measurement, a measurement target image of invisible light is always projected onto the fundus of the eye to be examined, superimposed on the chart image for subjective ophthalmoscopy. At this time, the index plate 12 is always driven to a position corresponding to the corrected power in the chart projection system. At this 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. 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, the state of the target image formed in the fundus of the eye to be examined is observed as a visible image, so that the eye examination can be performed by the patient. It is possible to easily judge in what condition the person is aiming at the chart image,
Accurate eye examination can be performed. Moreover, 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 observe the chart image itself. This has the advantage that a target image of any size and arbitrary shape can be projected, making observation extremely easy.

[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 general shape of the image rotator shown in FIG. 1, and 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 shown in FIG. 1, and FIG. 7 is a plan view showing the shape of the chart for subjective optometry used in the eye refractive power measuring device according to the present invention. 8 to 10 are plan views showing the imaging state of the measurement target image shown in FIG. 1, and FIG. 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, and FIG. 13 is a flowchart for explaining the measurement procedure of the refractive power measuring device for an ophthalmic instrument according to the present invention. FIG. 14 is an explanatory diagram for explaining the measurement procedure. 1... 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.

Claims (1)

[Scope of Claims] 1. 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 response of the examinee. The system includes an invisible light target image projection system that projects an invisible light target image onto the fundus of the subject's eye simultaneously with the projection of the chart image for subjective optometry, and a display section that displays the target image as a visible image. Features of the eye refractive power measuring device.