JPH08336499A - Eye refractometer - Google Patents

Abstract

PURPOSE: To provide an eye refractometer by which highly precise measurement can be performed regardless of local turbidity of a crystalline lens or a vitreous body in an eyeball, by equipping a waveform fairing means to fair the waveform outputted by a light detecting element by adjusting the waveform turbulence caused by local turbidity of a testee's eyeball in an outputted waveform from a light detecting element. CONSTITUTION: Detection of refraction is performed by measuring the phase difference between two photoelectric conversion elements 8b and 8c. That is, the outputs by photoelectric elements 8b and 8c are inputted to a microcomputer 28 through buffers 27b and 27c and the outputted waveform is once stored in a memory. When the waveform has discontinuity or irregularity, the part thereof is interpolated for fairing the outputted waveform. The output is inputted to a computer 26 through a phase difference counter 30 to be inputted to a CRT controller 35 of a CRT monitor 36.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an eye refractive power measuring device, and more particularly to an objective eye refractive power measuring device equipped with a fog device.

[0002]

2. Description of the Related Art In an optometric apparatus for automatically measuring the refractive power of an eye to be examined, a so-called objective eye refractive power measuring apparatus, the refractive power is detected while the eye to be examined is fixed and relaxed. For example, as disclosed in Japanese Patent Laid-Open No. 55-86437, the fundus of the eye to be examined is scanned with a light beam, the scanning light beam from the fundus is received by a light receiving element, and the refractive power is output based on the output of this light receiving element. Devices that perform detection are known.

[0003]

As described above, in the conventional eye refractive power measuring apparatus, the refractive power is measured based on the output of the light receiving element that receives the scanning light beam from the fundus. However, when there is local lens opacity or vitreous opacity in the eyeball of the eye to be inspected, waveform distortion occurs in the output waveform of the light receiving element, and it becomes impossible to measure the refractive power.
Alternatively, there is the inconvenience that only measurement values with low reliability can be obtained.

The present invention has been made in view of the above-mentioned problems, and an eye refractive power measuring device capable of highly accurate refractive power measurement even if there is local lens opacity or vitreous opacity in the eyeball. The purpose is to provide.

[0005]

In order to solve the above-mentioned problems, in the present invention, a light beam is projected onto the fundus of the eye to be examined,
In the eye refractive power measuring device for measuring the refractive power of the eye to be inspected based on the output of the light receiving element that receives the reflected light from the fundus of the eye to be inspected, in the eyeball of the eye to be inspected in the output waveform from the light receiving element. Further, a waveform shaping means for shaping the output waveform from the light receiving element by correcting the disturbance of the waveform due to local turbidity, and the refractive power based on the shaped waveform from the waveform shaping means There is provided an eye refractive power measuring device characterized by measuring

According to a preferred aspect of the present invention, the degree of opacity in the eyeball of the eye to be inspected is detected based on the degree of disturbance of the waveform in the output waveform from the light receiving element.

[0007]

In the eye refractive power measuring device, the fundus of the eye to be inspected is scanned with, for example, a slit-shaped light beam, and the scanning light beam from the fundus of the eye to be inspected is received by the pair of light receiving elements through the corresponding slit-shaped openings. Then, the refractive power of the eye to be inspected is measured based on the phase difference between the photoelectric output signals of the respective light receiving elements. In general, waveform distortion does not occur in the output waveform of each light receiving element for a normal eye without opacity in the eyeball or an eye to be examined with uniform opacity in the eyeball. However, if there is local lens opacity or vitreous opacity in the eyeball of the eye to be inspected, waveform distortion occurs due to the local opacity.

Therefore, in the present invention, the output waveform from the light receiving element is temporarily stored and analyzed to determine whether the waveform has a discontinuous portion or an irregular portion, that is, whether the waveform has a disturbance component. When it is determined that the waveform has a discontinuous or irregular portion, the discontinuous or irregular portion is interpolated. In this way, it is possible to accurately detect the phase difference of each output signal, and thus the refractive power of the eye to be inspected, based on the waveform shaped by correcting the turbulent component of the waveform. Also, based on the degree of disturbance of the waveform of the output waveform, that is, the degree of shaping,
The degree of opacity of the eye to be inspected can also be detected to some extent.
In this case, it is preferable that the detected degree of turbidity is quantified by digitization and the like and displayed by an appropriate display means.

[0009]

Embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a diagram showing a configuration of an optical system of an eye refractive power measuring device according to an embodiment of the present invention. The eye-refractive-power measuring device according to the present embodiment includes a refractive-power detector and a fog device.
The measurement principle of the refractive power detector is based on the screening method, and the eye refractive power is measured by detecting the speed of movement of the shadow on the pupil. An objective eye refractive power detector using a screening method is disclosed, for example, in JP-A-55-86437.

The eye-refractive-power measuring device shown in FIG. 1 includes a light-emitting diode 1 which emits infrared light as a light source for measuring the refractive power. An image of infrared light emitted from the light emitting diode 1 is configured to be formed on the pupil of the eye 3 to be inspected by the action of the condenser lens 2. The light emitting diode 1 and the condenser lens 2 are surrounded by a chopper 4 made of a hollow cylinder. The chopper 4 is formed with a plurality of slit-shaped openings S along the circumferential direction. The longitudinal direction of the opening S is perpendicular to the paper surface of FIG.

The chopper 4 is configured to rotate around the light emitting diode 1 by a drive system (not shown). The linear luminous flux that has passed through the slit-shaped opening S formed in the chopper 4 enters the half mirror 5. The half mirror 5 reflects the infrared light from the light emitting diode 1 toward the eye 3 to be inspected. The infrared light reflected by the half mirror 5 enters a measuring radius line rotation system 6 including a prism 6a and a mirror 6b. The measurement radius line rotation system 6 is an optical system for observing the astigmatic state of the subject's eye 3. That is, by integrally rotating the prism 6a and the mirror 6b about the optical axis A, the radial direction of the linear light flux incident on the subject's eye 3 changes.

In this way, a light source image is formed on the pupil plane of the eye 3 to be inspected, and the fundus of the eye 3 to be inspected is scanned by the linear light beam as the chopper 4 rotates. On the other hand, the reflected infrared light from the eye 3 to be inspected is transmitted through the measurement radial line rotating system 6 and the half mirror 5, and then the objective lens 7
Incident on. Then, the image of the pupil plane of the subject's eye 3 through the objective lens 7 is formed on the light receiving portion 8 through the diaphragm 9. The diaphragm 9 has a slit-shaped opening having a longitudinal direction in a direction perpendicular to the paper surface of FIG. 1, and this opening is positioned substantially on the focal point of the objective lens 7.

The light receiving portion 8 comprises a substrate 8a, photoelectric conversion elements 8b and 8c for measuring the refractive power, which are fixed on the substrate 8a, and a four-division photoelectric conversion element 8d for detecting a positional deviation. As is apparent from FIG. 1, the photoelectric conversion elements 8b and 8c
Are arranged in a direction corresponding to the scanning direction of the linear light flux on the eye 3 to be inspected. The four-division photoelectric conversion element 8d arranged between the photoelectric conversion elements 8b and 8c is a view of the light receiving unit 8 viewed from the direction of the objective lens 7, and the four photoelectric conversion elements 8d arranged as shown in FIG. It is composed of _{1 to} 8d ₄ . Further, the centers O of the _four photoelectric conversion elements 8d _{1 to} 8d ₄ are adapted to coincide with the optical axis A of the objective lens 7. In this way, the optical system of the refractive power detector is composed of the light emitting diode 1, the condenser lens 2, the chopper 4, the half mirror 5, the measuring radius line rotating system 6, the objective lens 7, the light receiving portion 8 and the diaphragm 9. .

On the other hand, the optical system of the fog device is provided with a fixation target 11.
And a visible light source 10 that emits visible light to illuminate it. The fixation target 11 and the visible light source 10 are integrally held by a holding member 33, and the holding member 3
3 is reciprocally moved in the optical axis direction (direction shown by an arrow in the figure) by the action of a stepping motor described later.

The fixation target 1 illuminated by the visible light source 10
After passing through the projection lens 12 and the diaphragm 13, it is reflected by the mirror 14 and then enters the lens 15. The light from the fixation target 11 that has passed through the lens 15 is reflected by the half mirror 16 toward the eye 3 to be inspected, and is projected onto the retina via the lens of the eye 3 to be inspected. Thus
An image of the fixation target 11 is formed on the retina of the eye 3 to be inspected.
The lens 15 is for positioning the diaphragm 13 at a position optically conjugate with the pupil of the eye 3 to be inspected. In other words, the action of the lens 15 allows the size of the pupil to be kept optically constant even when the eye 3 to be inspected changes, and thus the depth of field to be kept constant.

If the refractive state of the lens of the subject's eye 3 is constant, the position of the fixation target 11 on which the image is formed on the retina of the subject's eye 3 is only one specific point on the optical axis. is there. That is, the position on the optical axis of the fixation target 11 on which an image is formed on the retina of the subject's eye 3 and the refractive power of the lens of the subject's eye 3 have a one-to-one correspondence. As described above, the optical system of the fog device includes the visible light source 10, the fixation target 11, the holding member 33, and the projection lens 1.
2, a diaphragm 13, a mirror 14, a lens 15, and a half mirror 16.

FIG. 2 is a view showing the arrangement of the electrical processing system of the eye-refractive-power measuring apparatus according to this embodiment. The signal processing procedure of the apparatus according to the present embodiment will be described with reference to FIG. The photocurrents generated in the four received photoelectric conversion elements 8d _{1 to} 8d ₄ are converted into the corresponding four amplifiers 20d ₁
It is converted to a voltage signal having a low impedance at 20 to 20d ₄ . The voltage signals output from the amplifiers 20d _{1 to} 20d ₄ are input to the adder / subtractor 21. Adder / subtractor 21
Is output from the _four photoelectric conversion elements 8d _{1 to} 8d ₄ ,
The X signal corresponding to the positional deviation of the corneal reflected light in the X direction (direction of the arrow in the figure), the Y signal corresponding to the positional deviation of the corneal reflected light in the Y direction (direction of the arrow in the figure), and the corneal reflected light A summation signal Z indicating the strength is output. The X and Y directions are in a plane perpendicular to the measurement optical axis A.

When the outputs of the amplifiers 20d _{1 to} 20d ₄ are v _{1 to} v ₄ , respectively, the X signal is (v ₁ + v ₂ )-
(V ₃ + v ₄ ), and the Y signal is (v ₁ + v ₄ ) − (v
₂ + v ₃ ). The three signals X, Y, and Z output from the adder / subtractor 21 are converted into DC voltages with their chopping frequency components suppressed in the low-pass filters 22a to 22c. Analog divider 23a, 23b
In order to prevent the coordinate signal from changing due to the difference in corneal reflectance, the X signal and the Y signal are each normalized.

In this way, the analog dividers 23a and 2
3b respectively normalized X coordinate signal and Y
The coordinate signal and the summation signal Z are continuously and alternately taken out by the analog switch 24. The extracted signal is A
After being converted into a digital signal in the -D converter 25, it is input to the computer 26. Computer 26
Drives the display circuit 37 to display the digitized X-coordinate signal and Y-coordinate signal in the AD converter 25.

On the other hand, the refractive power is detected by measuring the phase difference between the signals output from the two photoelectric conversion elements 8b and 8c. That is, since the fundus of the eye 3 to be inspected is scanned by the linear light flux due to the rotation of the chopper 4, when the eye 3 to be inspected is an emmetropic eye, the position of the slit 9 corresponds exactly to the neutralization point. Therefore, the luminous flux emitted from the opening of the slit 9 is uniformly brightened or darkened, and the phases of the output signals of the two photoelectric conversion elements 8b and 8c become equal.

When the eye 3 to be inspected is not an emmetropic eye, bright and dark stripes corresponding to the refractive error state of each eye are emitted from the opening of the slit 9, and the photoelectric conversion element 8 is formed.
The phases of the output signals b and 8c differ depending on the refractive error state of the eye to be examined. Thus, the photoelectric conversion elements 8b, 8
The refractive power of the eye to be inspected can be obtained from the phase difference between the output signals of c.

FIG. 3 is a diagram showing an example of output waveforms of the photoelectric conversion elements 8b and 8c when the refractive power is measured for a normal eye having no opacity in the eyeball. On the other hand, FIG. 4 is a diagram showing an example of output waveforms of the photoelectric conversion elements 8b and 8c in the case where lens opacity or vitreous opacity is locally present in the eyeball of the subject's eye. As shown in FIG. 3, when the refractive power is measured for a normal eye with no cloudiness in the eyeball, the photoelectric conversion element 8
No waveform distortion occurs in the output waveforms of b and 8c. Therefore, the refractive power of the subject's eye can be accurately obtained from the phase difference between the output waveforms.

However, when there is opacity of the crystalline lens or opacity of the vitreous body in the eyeball of the subject's eye, that is, when there is a light shield in the eyeball of the subject's eye, the photoelectric conversion element 8b,
It becomes difficult to obtain the refractive power of the eye to be examined based on the output waveform of 8c. Of course, when the inside of the eyeball of the subject's eye is uniformly clouded, the refractive power of the subject's eye can be measured with a certain degree of accuracy by increasing the amount of light. However, when opacity is locally present in the eyeball of the eye to be inspected, as shown in FIG. 4, waveform distortion occurs in the output waveforms of the photoelectric conversion elements 8b and 8c. As a result, it is not possible to accurately measure the phase difference between the output waveforms, and thus the refractive power of the eye to be inspected, based on the output waveforms of the photoelectric conversion elements 8b and 8c.

Therefore, in this embodiment, the photoelectric conversion element 8
The output waveforms from b and 8c are temporarily stored and analyzed whether the waveform has a discontinuous portion or an irregular portion. When it is determined that the waveform has a discontinuous or irregular portion, the discontinuous or irregular portion is interpolated as indicated by a broken line in FIG. In this way, the phase difference between the output waveforms, and thus the refractive power of the eye to be inspected, is accurately measured based on the waveform shaped by correcting the turbulence component of the waveform.

That is, the two photoelectric conversion elements 8b and 8c
Output of each of the buffers via the buffers 27b and 27a.
It is input to the microcomputer 28. The microcomputer 28 temporarily stores the output waveforms from the photoelectric conversion elements 8b and 8c and analyzes whether the waveform has a discontinuous portion or an irregular portion. When it is determined that the waveform has a discontinuous or irregular portion, the discontinuous or irregular portion is interpolated to shape the output waveform. In this way, the microcomputer 28 constitutes a waveform shaping means for shaping the output waveform by correcting the disturbance of the waveform caused by the local opacity in the eyeball of the eye to be examined.

The waveform shaped by the microcomputer 28 is shaped into a square wave by the waveform shaping circuits 29b and 29a. The outputs of the waveform shaping circuits 29b and 29a are converted by the phase difference counter 30 into the number of pulses corresponding to the phase difference, and then input to the computer 26.
Signals are alternately input to the computer 26 from the AD converter 25 and the phase difference counter 30 described above.

When the X signal and the Y signal each show a substantially zero level and the sum signal Z is above a predetermined level (this becomes an alignment signal), that is, when the eye to be inspected and the apparatus main body are aligned, According to the digital signal output from the phase difference counter 30, a predetermined pulse is output to the drive circuit 32 of the stepping motor 31 as a drive signal. Here, the summation signal Z is taken into consideration when X is detected even if the eye to be inspected and the apparatus body are largely displaced.
This is because the signal and the Y signal may exhibit almost zero level.

The stepping motor 31 is used for the visible light source 10
A member 33 that integrally holds the fixation target 11 and the fixation target 11 is driven. As described above, there is a one-to-one correspondence between the refractive power of the eye 3 to be inspected and the position of the fixation target 11 imaged on the retina of the eye 3 to be inspected. In order to relax the eye 3 to be inspected, it is necessary to form the fixation target image slightly ahead of the retina so that the eye 3 to be inspected points to the far point. Therefore, in consideration of this point, the position of the holding member 33, that is, the position corresponding to the signal corresponding to the refractive power of the eye 3 (in this embodiment, the signal corresponding to the phase difference between the output signals of the photoelectric conversion elements 8b and 8c), The position of the fixation target 11 is determined.

After confirming that there is no displacement between the eye 3 to be inspected and the main body of the apparatus and that the eyelashes of the person to be inspected are not in the measurement optical path, the measurer turns on the measurement start switch 34 and turns on the computer 26. Input the measurement start signal. When the measurement start signal is input, the computer 26 activates the automatic fog device. When the fluctuation of the output of the phase difference counter 30 becomes small and the feedback system becomes stable, the computer 26 receives the output signal of the phase difference counter 30, converts it into a frequency, and inputs it to the CRT controller 35 of the CRT monitor 36. In this way, the CRT monitor 36 displays the refractive power (power) of the subject's eye measured in a substantially relaxed state.

As described above, in the present embodiment, even if the lens opacity or the vitreous opacity is locally present in the eyeball, highly accurate refractive power measurement can be performed. On the contrary, the degree of opacity of the eye to be examined can be detected to some extent based on the degree of disturbance of the waveform of the output waveform. Then, the detected degree of turbidity can be digitized and displayed on a CRT monitor or the like. Further, in the above-described embodiment, an example in which the image inspection method is used as the measurement principle of the eye refractive power detector is shown. However, the screening method is only one of the measurement principles of the eye refractive power detector. Therefore, the present invention is not limited to this measurement principle and can be applied to other measurement principles.

[0031]

[Effect] As described above, the eye refractive power measuring device of the present invention enables highly accurate refractive power measurement even if there is local lens opacity or vitreous opacity in the eyeball.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an optical system of an eye refractive power measurement device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of an electrical processing system of the eye refractive power measuring device according to the present embodiment.

FIG. 3 is a diagram showing an example of output waveforms of photoelectric conversion elements 8b and 8c when refracting power is measured for a normal eye without opacity in the eyeball.

FIG. 4 is a diagram showing an example of output waveforms of photoelectric conversion elements 8b and 8c in the case where lens opacity or vitreous opacity is locally present in the eyeball of the eye to be examined.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light emitting diode 2 Condenser lens 4 Chopper 6 Measuring diameter line rotation system 8 Light receiving part 8b, 8c Photoelectric conversion element 8d Photoelectric conversion element 10 Visible light source 11 Fixation target 12 Projection lens 28 Microcomputer 30 Phase difference counter 31 Stepping motor 32 Drive circuit 34 Measurement Start Switch 35 CRT Controller 36 CRT Monitor 37 Display Circuit

Claims (2)

[Claims] 1. An eye-refractive-power measuring apparatus for projecting a light flux onto the fundus of an eye to be inspected and measuring the refracting power of the eye to be inspected on the basis of the output of a light-receiving element for receiving reflected light from the fundus of the eye to be inspected, By correcting the disturbance of the waveform due to local opacity in the eyeball of the eye to be examined in the output waveform from the light receiving element, further comprising a waveform shaping means for shaping the output waveform from the light receiving element, An eye-refractive-power measuring device for measuring the refractive power based on the waveform shaped by the waveform shaping means. 2. The eye refracting power according to claim 1, wherein the degree of opacity in the eyeball of the eye to be inspected is detected based on the degree of disturbance of the waveform in the output waveform from the light receiving element. measuring device.