JPH07323005A - Apparatus for measuring refractive force of eye - Google Patents

Abstract

PURPOSE:To obtain an apparatus for measuring the refractive force of eyes which can measure the change in the refractive force of eyes in real time even when the eye to be examined is not faced accurately to the apparatus. CONSTITUTION:An eye 1 to be examined is illuminated alternately by two light sources 5 and 5', arranged at a distance left and right from an optical axis to obtain the ratio of the change in reflected light flux distribution of both light sources 5 and 5' from the eyeground of the eye to be examined and the refractive force of the eye 1 to be examined is measured based on this result.

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 eye-refractive-power measuring device capable of measuring a change in eye refractive power in real time.

[0002]

2. Description of the Related Art Conventionally, as a multi-faceted eye refractive power measuring device, there is known a device such as a so-called autorefractometer as disclosed in JP-A-2-154732.

[0003]

However, in the autorefractometer, it is necessary for the subject to fix the position of the eyeball at a certain position with respect to the device for measurement, and not only continuous measurement but also work is performed. The measurement was impossible.

In view of the above situation, the present invention is small and lightweight so that the measurement can be carried out with the measuring section attached to the head, and the subject does not need to maintain a certain posture, for example, the front view state, and It is intended to provide an eye-refractive-power measuring device capable of continuously obtaining eye-refractive-power data in real time.

[0005]

The eye refractive power measuring device of the present invention is placed at a position substantially optically conjugate with a projection system for illuminating a subject's eye and forming a light source image on the fundus and a pupil of the subject's eye. A test light source having a light receiving system for detecting a distribution of reflected light from the fundus of the eye, the light source of the light projecting system is composed of two light sources arranged slightly apart from the optical axis to the left and right, and the light receiving system is a light receiving element, 2 above
And a means for obtaining a ratio of changes in light quantity at two or more points on the light receiving element when two light sources are alternately emitted, and a means for measuring an eye refractive power of an eye to be examined using the ratio as a parameter. To do.

In the eye refractive power measuring device of the present invention, the widths of the two light sources are extended in the direction perpendicular to the optical axis thereof.

In the eye-refractive-power measuring device of the present invention, in a portion of the detector which is in a conjugate relationship with the pupil of the subject's eye, the light amount change is non-zero depending on the eye-refractive power of the subject's eye in most of the region. This value corresponds to the eye refracting power, and the eye refracting power can be measured based on the parameter obtained by changing the light amount at least at two or more points. By setting the light amounts of the two light sources to be equal to each other except for the portion having a conjugate relationship with the pupil, the change in the light amount can be made substantially zero.

[0008]

Embodiments of the present invention will be described below with reference to the drawings.

In the first embodiment of the present invention, as shown in FIG. 1, a light projecting system 2 and a light receiving system 3 are arranged opposite to each other through a common half mirror 4 as shown in FIG. The subject eye 1 is illuminated by two linear or rectangular uniform light sources 5 and 5'which are alternately turned on and have a certain size via 2 to form a light source image on the fundus 6. This light source image acts as a secondary light source for illuminating the pupil 7 from the back side with respect to the light receiving system 3. The light source may be visible light or near infrared light that does not affect the subject.

The light receiving system 3 comprises a rectangular mask 8 having an opening on the optical axis, a lens 9 and a detector 10. Two sides of the rectangular mask 8 are conjugated with the light sources 5 and 5'with respect to the half mirror 4. No position, and the above detector 1
Reference numeral 0 is composed of a two-dimensional imager such as a CCD, an image pickup tube or a photoelectric conversion element such as a plurality of light amount sensors, and is arranged at a position conjugate with the pupil 7 of the subject eye by the lens 9.

FIG. 2 shows the relative positional relationship between the rectangular mask 8 and the light sources 5 and 5'as seen from the test eye.

The output from the detector 10 is used in addition to the light amount change detector 11 to detect the light amount change when the light source 5 is turned on and when the light source 5'is turned on. It is converted into force D and displayed on the display 13.

Since the eye-refractive-power measuring apparatus of the present invention has the above-mentioned structure, the point P in the pupil 7 when the light source 5 is turned on.
Is illuminated with the light source image formed on the fundus 6 as a secondary light source, and the optical path of the fundus reflected light passing through the point P is as shown in FIG. Point P
The optical path of the fundus reflected light passing through is as shown in FIG.
Here, a method of converting the light amount change detected by the light amount change detector 11 into eye refractive power D (diopter) will be described.

3 and 4, a dotted line is a line connecting the center of the fundus light source with the center of the pupil 7 of the subject eye and each side of the rectangular mask 8, and a chain line is a center line of a light beam passing through the point P.

Since the retina conjugate point O is a conjugate point of the fundus 6, the dotted line and the alternate long and short dash line intersect with each other in the vicinity O'or O "of the retina conjugate point O.

In order to evaluate the change in the amount of light at the point Q on the detector 10, the light flux passing through the mask, which is shaded with respect to the total light flux from the fundus 6, when the light source 5 is turned on and when the light source 5'is turned on. Find the percentage.

FIG. 5 is a diagram in which a light beam passing through the center Pc of the pupil 7 is drawn from the fundus 6 to the rectangular mask 8 when one of the light sources 5 is turned on. A light source image formed by one light source 5 is formed on the fundus 6, and the size of the light source image formed on the fundus 6 is determined by the angle at which the eye 1 to be examined watches the light source 5. Depending on the change in the eye refractive power of the subject's eye 1, the above-mentioned light source image is blurred and the image is enlarged, but for the purpose of the following evaluation of the amount of light, the effect of the blur is removed by integration, so the light source image without blur is generated. There is no problem in proceeding with the consideration.

Since the position of the retinal conjugate point O is conjugate with the fundus 6 at the visual position, when the light source image of the fundus 6 is considered as a secondary light source, the image of this secondary light source is formed here. Eye refractive power D
The relationship between and the viewing distance L is expressed by Equation 1.

[0019]

[Equation 1]

Obtaining the eye refractive power results in obtaining the viewing distance L. The diameter C at the mask position of the light beam entering the light receiving system 3 from the point Pc at the center of the pupil 7 is a unique value determined by the size of the light source 5 of the light projecting system 2, and as is clear from FIG. Since the upper half of the light flux emitted from the mask 8 is blocked by the mask 8, 1/2 of the total light flux always enters the light receiving system 3.

When the height of the point P from the optical axis is a in the pupil 7 as shown in FIG. 6, the light beam from the point P enters the light receiving system 3 via the point O ', and at this time, the center of the light beam is reached. The line intersects the optical axis at a point O ', and the distance between the center of the light beam and the side of the mask is b at the mask position.

If the distance from the eye 1 to be examined to the retinal conjugate point O is L, and the distance to the mask 8 is L ₀ , then a,
The relationship between b, L, and L ₀ is expressed by Equation 2.

[0023]

[Equation 2]

The above value b is obtained from the ratio of the luminous flux incident on the light receiving system 3 and the total luminous flux I _O. The amount of light incident on the light receiving system 3 from the point Pc is (1/2) _IO , and is (1/2).
I _O = k · C / 2 (where k is a proportional coefficient), and I = k [(1/2) C + b], where I is the amount of light incident on the light receiving system 3 from the point P. .

Next, referring to FIGS. 7 and 8, the other light source 5 '
A light flux passing through the point P when is turned on will be described.

If the amount of light emitted from the light source 5'is made equal to the amount of light emitted from the light source 5, then I '= k [(1/2) C-b, where I'is the amount of light entering the light receiving system 3 from the point P. ] It becomes.
Therefore, when the two light sources 5 and 5'blink alternately, the light amount change becomes I'-I = k (-2b), and the ratio of the light amount change to the total luminous flux is shown in Formula 3.

[0027]

[Equation 3]

Here, (I'-I) / I _O is a measured value, and C is a predetermined value as described above, so b can be obtained by the equation (4).

[0029]

[Equation 4]

When Equations 1 to 4 are put together, Equation 5 for obtaining the eye refractive power D is obtained.

[0031]

[Equation 5]

[0032] Other obtained from the light quantity I _O light quantity from the input signal before the light amount change detector 11 of the subject eye pupil surface center, is also determined from the value integrated by averaging the amount of light in the pupil range.

[0033] Although is a description of the case the distance L from the subject eye 1 to the retina conjugate point O is also closer than the distance L _O to the mask 8, L is similarly true for the case further than L _O.

Next, let us consider the luminous flux entering the light receiving system 3 when the light sources 5 and 5'are turned on for the point R other than the pupil.

Since the point R is a point on the diffusing surface which is directly illuminated by the light source, it scatters light in all directions when illuminated by the light source 5 or 5 '. The light flux that is captured and reaches the conjugate point S on the detector 10 is only the light flux that passes through the mask 8. Light source 5
Since the amounts of emitted light of 5 and 5'are equal, the mask 8
Since the opening area of the light source does not change, the light amount change when the light sources 5 and 5'blink becomes zero.

FIG. 9A shows the detector 1 when the light source 5 is turned on.
0 shows the light amount distribution on 0, and FIG. 9B shows the light amount distribution on the detector 10 when the light source 5'is turned on. 9A and 9B, the horizontal axis represents the light amount and the vertical axis represents the position of the detector 10.

From this result, the output of the light quantity change detector 11 is as shown in FIG. 9C. If when the distance L from the subject eye 1 to the retina conjugate point O is also farther than the distance L _O to the mask 8, increasing or decreasing relationship light amount change is reversed. Light source 5,
If the emitted light amounts of 5'are made equal, the light amount does not change at the portion other than the conjugate point of the pupil 7, and the light amount changes at the conjugate point of the pupil 7. Since this light amount change amount has a constant relationship with the eye refractive power according to the equation 5, the eye refractive power of the subject eye can be known by measuring the light amount change amount.

In the second embodiment of the present invention, as shown in FIG. 10, the width of the light sources 5 and 5'is set in the direction perpendicular to the optical axis thereof, for example, to the right by ½ of the width of each light source. The extended light sources 14 and 14 'are formed by extension, and the light from these extended light sources is bent by the half mirror 4 and made incident on the eye 1 to be examined. FIG. 11 shows the relative positional relationship between the mask 8 and the light sources 5, 5 ′, 14, 14 ′ as seen from the eye 1 to be examined in this case.

In this case, the luminous flux from each extended light source is the fundus 6
A secondary light source is generated to illuminate the pupil 7 with respect to the light receiving system 3 from the back surface. When the light source 5 is turned on, the light flux from the fundus extension light source image always passes through the opening of the mask 8, whereas the light source 5 When ′ is turned on, the light flux from the fundus extension light source image is always blocked by the mask 8 and does not reach the detector 10.

FIG. 12A shows the light amount distribution on the detector 10 when the light source 5 is turned on, and FIG. 12B shows the light amount distribution on the detector 10 when the light source 5'is turned on in this case. The output of device 11 is shown in FIG. 12C.

In this way, since the light source light amount information can be included in the light amount change amount of the pupil conjugate point, the number of signal processing systems can be reduced and the process of extracting the pupil portion to be processed in the signal processing is simple. There is also an advantage that a digitization circuit is sufficient.

The extended light sources 14 and 14 'are the light sources 5 and 5, respectively.
It may be a point light source independent of 5 '.

[0043]

As described above, in the eye-refractive-power measuring device of the present invention, the parameter is calculated by focusing only on the portion where the light amount change of the detector is not zero, and the eye-refractive power is obtained. Since the amount of processing is small and the eye refractive power can be measured in real time, the repetition rate of the measurement can be increased, so that the temporal change of the eye refractive power can be continuously measured, which is an excellent effect.

Even when the eye to be examined is not directly facing the device, the difference between the measured eye refractive power and the true eye refractive power depends on the azimuth and angle between the optical axis of the device and the visual direction. Since there is a certain relationship that depends on the eyes of the subject, if this relationship is obtained in advance, the subject can make continuous measurements without looking at the optical axis of the device and looking at any direction. .

Further, the pupil diameter can be easily obtained in the process of the above detection, and a virtual image of the light source is generated near the pupil of the subject's eye due to the reflection of the illumination light by the cornea, and this virtual image changes the viewing direction of the eyeball. Since the position is changed together with the processing device for detecting the position of the virtual image, the visual direction of the subject's eye can be simultaneously measured.

Therefore, according to the present invention, it is possible to obtain many effects such that accommodation, eye movement, and pupil reaction, which are said to be the three major functions of the eye, can be simultaneously measured continuously in real time.

Further, since it is small and lightweight, it has various advantages such as easy handling.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a basic configuration of an eye refractive power measuring device of the present invention.

FIG. 2 is an arrangement of a mask and a light source seen from a test eye in the eye refractive power measuring device of the present invention.

FIG. 3 is an explanatory diagram showing a state of a light flux when one light source is turned on in the eye refractive power measuring device of the present invention.

FIG. 4 is an explanatory diagram showing a state of a light flux when the other light source is turned on in the eye refractive power measurement device of the present invention.

FIG. 5 is an explanatory diagram in which a part of the light flux is drawn out in FIG.

FIG. 6 is an explanatory diagram in the case of calculating the eye refractive power from the state of the light flux in the eye refractive power measuring device of the present invention.

FIG. 7 is an explanatory diagram in which a part of the light flux is drawn out in FIG.

FIG. 8 is an explanatory diagram in the case of calculating the eye refractive power from the state of the light flux in the eye refractive power measuring device of the present invention.

FIG. 9A is an explanatory diagram of a light amount distribution on a detector when one light source is turned on in the eye refractive power measurement device of the present invention.

FIG. 9B is an explanatory diagram of a light amount distribution on a detector when the other light source is turned on in the eye refractive power measuring device of the present invention.

FIG. 9C is an explanatory diagram of changes in the light amount distribution shown in FIGS. 9A and 9B.

FIG. 10 is an explanatory diagram of a second embodiment of the eye refractive power measurement device of the present invention.

FIG. 11 is an arrangement of a mask and a light source seen from a test eye in the second embodiment of the present invention.

FIG. 12A is an explanatory diagram of a light amount distribution on a detector in the second embodiment of the eye refractive power measurement device of the present invention.

FIG. 12B is an explanatory diagram of a light amount distribution on a detector in the second embodiment of the eye refractive power measurement device of the present invention.

FIG. 12C is an explanatory diagram of changes in the light amount distribution shown in FIGS. 12A and 12B.

[Explanation of symbols]

 1 Test Eye 2 Light Emitting System 3 Light Receiving System 4 Half Mirror 5 Light Source 5'Light Source 6 Fundus 7 Pupillary 8 Rectangular Mask 9 Lens 10 Detector 11 Light Intensity Change Detector 12 Calculator 13 Display 14 Extended Light Source 14 'Extended Light Source

Claims (2)

[Claims] 1. A light receiving system for illuminating the eye to be examined and a light receiving system for forming a light source image on the fundus and a light receiving system for detecting a distribution of light flux reflected from the fundus of the eye to be examined, which is placed at a position substantially optically conjugate with the pupil of the eye to be examined. The light source of the light projecting system is composed of two light sources arranged slightly apart from the optical axis to the left and right, and the light receiving system includes the light receiving element and the light receiving element when the two light sources are alternately emitted. An eye-refractive-power measuring device comprising: a means for obtaining a ratio of changes in light quantity at two or more points above; and a means for measuring the eye-refractive power of a test eye using the ratio as a parameter. 2. The eye refractive power measuring device according to claim 1, wherein the widths of the two light sources are extended in a direction perpendicular to the optical axes thereof.