JPH03184524A - Eye refraction capacity measuring apparatus - Google Patents

Abstract

PURPOSE:To enable the judging whether a measurement is proper or not by displaying a still image stored in a memory section on a display section to allow discrimination of results of the measurement by a visual sense. CONSTITUTION:A video of a photodetecting element 9 is picked up into a frame memory 16 by one or in plurality and the image picked up is displayed on a display device 14. An inspecting person observes an image of an eye to be inspected shown on the display device 14. An arithmetic processing section 17 performs an arithmetic processing based on the video stored in the frame memory 16. A position of a bright spot image generated by a cornea reflection is detected and a position of a center of gravity of a bright spot, a distance between center of gravity positions of two bright spots and an inclination of a straight line connecting both the bright spots are determined for both eyes. Bright spots of both eyes are removed based on the position of center of gravity of the bright spot and a quantity of light distribution is determined and diopter values of an eye to be inspected is determined by a quantity of light distribution for measurement. The position of the bright spot determined by computation is displayed on the display device 14 being superimposed on the picked-up image as base of the measurement from the frame memory 16. Moreover, a corrected image after the removal of the bright spot and the quantity of light distribution for measurement can be displayed simultaneously, thereby obtaining proper results of the measurement.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an eye refractive power measuring device, and particularly to an eye refractive power measuring device that is useful for children and infants.

[Prior Art] Conventionally, eye refractive power measurement devices include a so-called subjective ophthalmoscope that measures eye refractive power based on the response of a test subject, and a so-called autorefractometer that measures the eye to be examined objectively. The device is known.

However, when measuring infants with this type of device,
Measurements cannot be performed with a subjective ophthalmoscope because the infant's cooperation cannot be obtained.Also, with a general autorefractometer, the position of the eye to be examined must be fixed, but in the case of infants, it is difficult to fix the position of the eye to be examined. It had the disadvantage that measurement was extremely difficult.

In order to eliminate these drawbacks, a so-called photorefraction method is used, in which the fundus of the eye to be examined is illuminated with strobe light, the state of the light flux at the pupil of the eye to be examined is photographed with a camera, and the ocular refractive power of the eye to be examined is measured from the results. measurement or proposed.

In this photorefraction method of measurement, sufficient measurements can be made even if the optical axis of the eye to be examined is slightly shifted.
This method is said to be useful for measuring the eye refractive power of infants and young children in whom it is difficult to fix the subject's eye.

In such a photorefraction type eye refractive power measuring device, since it attempts to obtain measurement results by capturing instantaneous moments, the line of sight of the eye to be examined coincides with the measurement optical axis, and the examinee does not blink. It must be possible to obtain measurement images when the camera is not in use.

In the conventional method, the examiner looks at the patient's eyes on the monitor screen, confirms that the eyes are open, and then performs the measurement, and then displays the images and measurement results obtained during the measurement. from,
The examiner was checking to see if there was a shift in the patient's line of sight, or if the patient was blinking.

[Problem to be solved by the invention] However, in the conventional method described above, - degree measurement is performed, calculation processing is performed, and the examiner looks at the result and the measurement image and makes a judgment, so the measurement result is not valid. However, if re-measurement is required instead of the test result, there is a problem in that re-measurement takes time and puts a heavy burden on the subject.

Furthermore, the judgment of whether a measurement result is valid or invalid must be made by the examiner, and human error is inevitable, leading to ambiguity and accuracy problems.

In view of these circumstances, the present invention makes it possible to instantly determine whether or not the subject blinked during measurement and whether or not there was a shift in line of sight, visually distinguish the measurement results, and determine whether or not the measurement was appropriate. The purpose of the present invention is to provide an eye refractive power measuring device that can

[Means for Solving the Problems] The present invention includes a display section for displaying a pupil image of the subject's eye, and a positioning of the subject's eye based on the pupil image of the subject's eye displayed on the display section. In an eye refractive power measuring device that has a storage section that stores still images, and measures eye refractive power by calculating a light amount distribution based on the still images stored in the storage section, the storage section stores the still images. The still image is displayed on the display unit.

[Function] The image captured for measurement is displayed, and the examiner can check whether the measurement is appropriate before issuing the measurement result. Additionally, the process of obtaining measurement results is displayed as necessary.

[Example] An embodiment of the present invention will be described below with reference to the drawings.

The present applicant has proposed a useful eye refractive power measuring device in the previous Japanese Patent Application No. 63-238505, and this example describes the case where it is implemented in the eye refractive power measuring device related to the patent application. do.

First, the eye refractive power measuring device according to the previous application will be explained.

In FIG. 1, 1 is a projection system for projecting a light source image onto the fundus 7 of the eye 3 to be examined, and 2 is a light receiving system for receiving the light beam 10 reflected by the fundus 7. 1 and the light receiving system 2 are arranged facing the eye 3 to be examined.

The projection system 1 includes a light source 4 and a half mirror 5 for reflecting the light beam 11 from the light source 4 toward the eye 3 to be examined.The projection system 1 directs the light beam 11 from the light a4 through the pupil 6 onto the fundus 7. It projects so as to form an image of the light source 4 on the
The distance between the light source 4 and the eye 3 to be examined is set so that the image of the light source 4 is focused on the fundus 7 when the eye refractive power of the eye 3 to be examined is a reference diopter value (reference refractive power).

The light receiving system 2 includes an objective lens 8 and a light receiving element 9, and a light beam 10 from the fundus 7 passes through a half mirror 5 and is guided onto the light receiving element 9.

The light receiving element 9 is an area CCD, an image pickup tube, or two of these.
The light-receiving surface 9a of the light-receiving element 9 is arranged at a conjugate position with the pupil 6 of the eye 3 to be examined with respect to the objective lens 8.

In the optical path of the light receiving system 2, there is an etched light shielding member 12 located at a position conjugate with the light source 4 with respect to the half mirror 5, for shielding one beam of light 10 with the optical axis O of the objective lens 8 as a boundary.
Place.

Further, a computing unit 13 is connected to the light receiving element 9, and the computing unit 13 computes a diopter value from the light receiving state of the light receiving element 9 and the light amount distribution, and outputs the result to a display 14. .

Next, the eye refractive power measurement in the eye refractive power measuring apparatus having the above configuration is performed as follows.

As shown in FIG. 2(A), when the diopter value of the eye 3 to be examined is negative compared to the reference diopter value, the image of the light source 4 is formed in front of the fundus 7, and this luminous flux Considering a light beam 10 reflected at one point on the optical axis on the illuminated fundus 7, this light beam 10 is reflected by the light shielding member 12.
The upper half (shaded area) of the light beam that is focused in front of the subject's eye 3, and projected onto the light receiving element 9 by the objective lens 8.
is shaded. On the other hand, as shown in FIG. 2(B), when the diopter value of the eye to be examined is the deopter value or the reference diopter value, the luminous flux 10 is focused on the light shielding member 12, and the luminous flux 10
is not blocked by the light blocking member 12.

Further, as shown in FIG. 2(C), when the diopter value of the eye 3 to be examined is more positive than the reference diopter value, the image of the light a4 is projected so as to form behind the fundus 7, and as described above. Similarly, the light beam 10 reflected by the fundus 7 is behind the light shielding member 12,
That is, in the light beam 10 that is condensed on the light receiving element 9 side and projected onto the light receiving element 9, a portion of the light beam opposite to that shown in FIG. 2 (8) (the upper half in the figure) is blocked.

The light flux projected onto the light-receiving surface 9a has a light quantity distribution state that changes depending on the magnitude, positive or negative, of the diopter value of the eye 3 to be examined with respect to the reference diopter value, and the diopter value is determined based on this light quantity distribution state.

The light-receiving element 9 is for detecting the light intensity distribution of the light flux formed on the light-receiving surface 9a, and the arithmetic unit 13 detects the distribution of the light flux formed on the light-receiving surface 9a based on the signal from the light-receiving element 9. The light intensity distribution is detected, and it is determined whether the eye refractive power of the eye to be examined is positive or negative with respect to the reference diopter value, and its absolute value is calculated, and the calculation result is output to the display 14.
4 displays the obtained results.

In the above embodiment, a half mirror is used as the beam separating means, but it goes without saying that various beam separating means such as a beam splitter or a polarizing prism may be used.

Further, in FIGS. 3(A) to 3([), the light amount distribution state of the light beam formed on the light receiving surface 9a will be explained.

In addition, in order to simplify the explanation in FIGS. 3(A) to fE), the optical axis of the light source 4 and the optical axis of the light receiving system are made to match, and the light shielding member 12 and the objective lens 8 are made to match. . Therefore, the light source 4 and the objective lens 8 are shown superimposed at the same position, and the light shielding member 12 is omitted.

3(A) to (E) show the case where the refractive power of the eye to be examined is negative with respect to the reference refractive power D0. shall be projected on top.

The distance between the light a4 and the pupil 6 of the eye to be examined is set to g, and the refractive power of the eye to be examined at which the image of this light source is focused on the fundus is defined as the reference refractive power D0.

FIG. 3(A) shows a point S on the axis of a slit-shaped light-a4 having a length L in the direction perpendicular to the optical axis when the refractive power of the eye to be examined is D (<D, ). It shows the projected light flux from point S. The image is once formed on So', and is projected onto the fundus 7 of the subject's eye as a blurred image. As D and -D become larger, the projected area 7a becomes wider.

FIG. 3(B) shows the state of the light flux reflected from the light receiving system 2 and the fundus 7 of the eye to be examined.

As shown in FIG. 3(B), considering the light flux from the point I-, at the end of the projection area on the fundus 7 of the eye to be examined, this point @I-
. Incidentally, the relational expression between this Q' and the refractive power of the eye to be examined is as follows.

On the other hand, if the pupil diameter of the eye to be examined is U, the spread width Δ of the light beam emitted from one point on the fundus is shown in Figure 3 (B).
As is clear from the equations (1) and (2), the refractive power of the eye 3 to be examined and the reference refractive power.

The larger the difference, the larger the area on the light shielding member 12.

Next, the spread of the light beam on the light receiving element 9 will be described.

The light receiving element 9 is always arranged in a conjugate manner with the pupil of the eye to be examined with respect to the objective lens 8, regardless of the refractive power of the eye to be examined 3.
When the diameter of the pupil 6 of the eye to be examined is U and the magnification of the objective lens 8 is β, a light beam is projected onto the light receiving element 9 in an area having a diameter of βU (which is not affected by the refractive power of the eye to be examined).

Similarly, the light beam from a point I, which is symmetrical to the above-mentioned I-o with respect to the optical axis, forms an image 1' at a position Q' from the pupil 6 of the eye to be examined, and then forms an image 1' in the same area on the light receiving element 9. Projected onto βU. When the light source 4 is a point light source and there is no light shielding member 12, each point I-1, ...■o, ... from the fundus 7 is
The integral of the luminous flux from Il determines the light quantity distribution on the light receiving element 9.

Here, in order to consider the light quantity distribution on the light receiving element 9, the light flux incident on the end position P-3 of the light beam projection position on the light receiving element 9, that is, the position of the radial cone with the optical axis as the center, is the third The luminous flux is limited to the range indicated by the diagonal line A in Figure (C). Similarly, considering the light beam incident on the optical axis at a position P that is symmetrical to the above-mentioned P- position, the light beam is limited to the range of the diagonal line A'. As a result, if an edge-shaped light shielding member 12 is placed at a distance 9 from the pupil 6 of the subject's eye (a position conjugate with the light source 4), the light beam A' on one side of the optical axis is placed. The light flux incident on the position 4 is not blocked by the light shielding member 12, and the light flux is gradually blocked as it goes upward from the position P-.
.

At the position P8, half of the luminous flux is blocked, and at the position P8, the entire luminous flux is blocked. Therefore, due to the etched light shielding member 12, the light on the light receiving element 9 becomes darker as it goes upward, and the light amount becomes 0 at the point P, resulting in a light amount distribution with a constant slope.

In Fig. 3 fA) to (C) above, only the light beam emitted from one point on the optical axis of the light source 4 is shown, but one point S-ca (where the size of the light source is L) at the end of the light source 4 is shown. 3(D).The light flux from this point S-1 is projected onto the fundus 7 of the subject's eye shown in FIG. .

The reflected light from the three points is the pupil 6 of the subject's eye as described above.
1 at a distance of 2' from , I are formed and then projected onto a region having a diameter of βU on the light receiving element 9. Here, among the luminous flux emitted from the point S-1 at the end of the light source 4, the luminous flux incident on the end position P- of the luminous flux projection on the light receiving element 9 is in the shaded area B in FIG. 3(D). It becomes a luminous flux.

Further, a point S of the light source 4 is symmetrical to the point S-3.

Considering the intertwined light flux and the light flux incident on the point P-1 on the light receiving element 9, it becomes the light flux in the shaded area C in FIG. 3 ([). In this way, when the light source 4 is considered to have a certain size, the amount of light at one point on the light receiving element 9 is:
It must be considered as the sum of the luminous flux from each point of the light source 4.

Based on this idea, Fig. 4 (8) shows the light fluxes incident on the position P- on the light receiving element 9 superimposed, and the light flux emitted from the position S-0 on the light source. Of these, the light flux that enters the position P-7 is in the area B (see Figure 3 (D)), and as the position on the light source moves upward, the light flux also moves upward, and the light source position on the axis S. Then A
The luminous flux is in the area of (see Figure 3 (C)), and at the position S on the light source, it is the luminous flux in the area of C (see Figure 3 (E)).
reference). Therefore, the amount of light at the point P-9 on the light receiving element 9 can be considered as the sum of these luminous fluxes.

Here, a light shielding member 1 is placed at a distance Q from the pupil 6 of the eye to be examined.
FIG. 4(B) is a schematic diagram showing the amount of light at point P- on the light-receiving element 9 when the light-receiving element 2 is placed.

FIG. 4(B) shows how the light beam is blocked by the light blocking member 12 as the position on the light source changes. In FIG. 4(B), the horizontal axis shows the coordinate position on the light source, and the vertical axis shows the light intensity. Considering the light flux from each point on the light source, the light flux at the coordinate position is blocked by the light shielding member 12. After passing the zero point of the coordinate position, the light is gradually blocked, and Δ(
All the light beams are blocked at the position of the above-mentioned spread of the light beams. Figure 4 (B) shows the contribution of the amount of light from each point on the light source, where k is the amount of light from each point on the light source when the light is not blocked, and the area of the shaded area is on the light receiving element. The area value T corresponding to the light amount value of point P-1 is as follows.

Similarly, other points on the light receiving element will also be considered. FIG. 5(^) shows the luminous flux incident on the center point P0 on the light receiving element in the same way as FIG. The light flux incident on the point is the hatched area of Bo, the center S on the light source. From the point S, the light flux from the point S on the light source becomes the light flux in the shaded area C0, and the amount of light incident on the center of the light receiving element 9 is as shown in FIG. 5(B). This corresponds to the area To of the shaded area. In other words, the light beams incident on the center point of the light receiving element from each point of the light source are blocked, and when the area value is calculated in the same manner as described above, it becomes the following value.

Similarly, the state of the luminous flux incident on point P7 on the light receiving element and the light amount value at this point are shown in Fig. 6(A) and Fig. 6(B).
), in Figure 6 (^), the light flux incident on point P out of the light flux from point S-3 on the light source is in the shaded area B', and from the center point S0 on the light source is in the area A. ”, shaded area, P- above the light source.

The luminous flux from the point P is shown as the luminous flux in the shaded area of C''. In this case, as shown in Figure 6 (8), from each point of the light source to the position of incidence on the point P of the light receiving element. , the luminous flux is not blocked, and after passing the -Δ position, the luminous flux is gradually blocked until it reaches 0.
All the light beams will be blocked at the position, and calculating the area value will yield the following value.

As can be seen from the results of these equations (5), (6), and (7), the light amount value on the light receiving element 9 gradually decreases from the bottom to the top.
When the light intensity distribution on the light receiving element is illustrated, it changes linearly as shown in FIG.

In the above description, the spread on the light shielding member 12 was explained based on the light beam emitted from one point on the fundus of the eye.

-Value. If the deviation ΔD of the deopter value of the eye to be examined is greater than or equal to a predetermined amount, a linear change as shown in FIG. In the case of Δ〉-, Fig. 4 (B
), Figure 5 (B), Figure 6 (B) are respectively Figure 11,
As shown in FIGS. 12 and 13, this light amount change does not show a linear change as shown in FIG. 7.

Next, when the refractive power of the eye to be examined shown in FIG. 2 (B) is the reference value, and when the refractive power of the eye to be examined shown in FIG. 2 (C) is more positive than the reference value, the same procedure as described above is applied. The light intensity distribution on the light-receiving element 9 can be considered. In this case, if the refractive power of the eye to be examined is the reference value, it will be a uniform distribution as shown in FIG. 8, and if the refractive power of the eye to be examined is positive, it will be a As shown in FIG. 9, the distribution state is opposite to that shown in FIG.

The slope of the above-mentioned light intensity distribution represents the diopter value (refractive power), and the direction of the slope represents the sign or negative of the diopter value.
This will be explained below with reference to FIG.

The spread Δ of the luminous flux described above, that is, the amount of blur Δ is determined by the above (4).
From equation (8), equation (10) makes it possible to calculate the deviation Δ of the deopter value of the eye to be examined from the deviation ΔD of the deopter value of the eye to be examined with respect to the standard deopter value D0, and further, as follows: The diopter value can be calculated using the formula.

D=D, 1ΔD −111) As described above, the diopter value of the eye to be examined can be determined from the distribution of the amount of light reflected from the fundus. Note that the above-mentioned light amount distribution is shown schematically, and in reality, the 14th
Changes in the light amount corresponding to each part of the eyeball shown in Figure (^) (see Figure 14 (B), Figure 14 fB) indicate the light amount distribution at the reference diopter value), that is, the cornea The protrusion ρ of the light amount at the bright spot 21 due to the reflection of
There is a drop in the amount of light σ in the portion of the iris 20 that is outside the pupil 6.

Furthermore, when determining the deviation ΔD of the diopter value from the above-mentioned light amount distribution, it is assumed that there is no influence of bright spots. Since the ff point affects the measurement result of the eye refractive power, it is preferable to remove the influence of the bright spot during measurement.

In the following, removal of the influence of bright spots will also be explained.

FIG. 15 is a block diagram schematically showing an embodiment of the present invention. In FIG. 6, 15 is an optical system of the eye refractive power measuring device, 9 is a light receiving element, 13 is a computing unit, 14 is a display, 16 is a frame memory that stores the image of the light receiving element 9 and the results of the arithmetic processing section; 17 is an arithmetic processing section; 18 is a control section that issues synchronization commands and sequence commands for the frame memory 16 and the arithmetic processing section 17; 19 is a measurement 17M The start switch 23 is a display changeover switch for displaying the image stored in the frame memory on the display 14.

This embodiment will be described below with reference to FIG. 16 to FIG. flS25.

The image of the subject or the image in the frame memory 16 can be selected on the display 14 by operating a display changeover switch 23, and in the measurement state, the image in the frame memory is displayed.

First, one or more images of the light receiving element 9 are captured into the frame memory 16, and the captured images are displayed on the display 14. Note that the captured images may be displayed in a single image or in a plurality of images.

The examiner observes the eye image displayed on the display 14.

FIG. 17(A) shows the screen on the display 14. On the display 14, a reference indicator 22R indicating a predetermined area,
An image of the eye to be examined is displayed superimposed on 221. A bright spot image is formed at the center of the pupil of the binocular image of the subject's eye, which is formed by the luminous flux reflected by the cornea of the subject's eye among the luminous flux from the light source 4. The examiner confirms that the binocular images are included in the indicators 22R and 221 and that the rough positioning adjustment has been completed, that the subject is pointing straight, and that the subject is not blinking. After confirming that, the measurement start switch 19 is turned on. If the subject is not looking straight or blinking, the image is further captured into the frame memo January 6.

As described above, when capturing multiple images into the frame memory 16, the time interval for capturing multiple image signals is preset to a time slightly longer than the time it takes for a normal person to blink (0°2 seconds). ing.

As a result, as described later, even if there is a blink in the first image signal, the image after the blink is stored in the next image signal, and the image is displayed using this video signal. All you have to do is make it to vessel 14.

Furthermore, by storing a plurality of images, it is possible to perform measurements individually using the image signals of these plurality of images, and by averaging the measurement results, even higher precision measurement becomes possible.

The arithmetic processing section 17 performs arithmetic processing through the steps described below based on the video stored in the frame memory.

First, the position of a bright spot image generated by corneal reflection is detected.

The image stored in the frame memory 16 is captured such that both eyes are in a predetermined area (corresponding to the areas of the indicators 22R and 22L mentioned above), for example, the right eye is included in (X,;Y,). . FIG. 17(B) is an enlarged view of this area.

The light amount is compared in each pixel of the light receiving element 9 within the <x,;y,> area of the frame memory 16, and a point 21p having the highest light amount value is determined. This point 21p is the point with the brightest amount of light in the bright spot image. FIG. 17(C) is an enlarged view of the peripheral area of this bright spot. A predetermined area (JX; JY) is set around this brightest point 210 of the 0th order.

The light amount values of each image are compared within this area, points of the image having a predetermined level or higher are extracted, and the center of gravity of the figure of the bright spot image formed by the set of these points (hereinafter referred to as the center of gravity of the bright spot) position 21G Calculate.

Next, a predetermined area (Xs;Ys) for bright spot erasure (described later) is set around this bright spot gravity center position 21G. Since bright spots formed by corneal reflection are not necessarily the brightest at the center, if a predetermined area for eliminating the bright spots is simply defined around the brightest point 21ρ, the bright spot image will protrude from this area. Is there a possibility that there is a possibility? However, if the luminescent point gravity center color ff21G is used as the center as described above, there is no such possibility.

For the left eye, the position 21G' of the center of gravity of the bright spot is calculated using the same procedure as described above.

Once the positions of the centers of gravity of the bright spots y121G and 21G' for both eyes are determined, the distance W between the positions of the centers of gravity of both bright spots and the width θ of the straight line connecting both bright spots are determined (see Figure 18). By determining the distance W between the points, it is possible to detect the distance between both eyes of the subject, that is, the interpupillary distance. Also, by determining the inclination, it is possible to detect how many degrees the subject is in relation to the apparatus. This amount of inclination can be used as a correction angle when measuring the astigmatic axis.

The center of gravity of the bright spot was found for both eyes on the above-mentioned owl, but
The bright spots of both eyes are then removed based on the position of the center of gravity of the bright spots.

Note that although the right eye will be described below, the same calculation processing is performed not only for the right eye but also for the left eye in the steps described below.

Once the center of gravity of the bright spot is determined, as mentioned above, it is shown in Figure 19 (B).
The detection area near the bright spot centered on the center of gravity of the bright spot (
Xs; Ys) is set.

The detection area (Xs;
The amount of light at points a and b, which intersect the boundary line of Ys), is determined, and these points a and b are approximated by straight lines. A straight line connecting points a and b indicates the light intensity distribution in which the influence of bright spots on the scanning line in the X direction in the detection area (Xs; Ys) has been removed (Fig. 19 (C)). (See, the light amount distribution indicated by δ in the figure shows the light amount distribution curve obtained by scanning the pupil portion in the X direction).

Therefore, the equation of the approximate straight line between points a and b is L-((Lb-L,)/xs　)XX+L.

...(12).

Such scanning is performed over the entire detection area (XB; yl+), and a correction value that removes the influence of the bright spot is determined and stored for the detection area (X,;Ys).

Next, scan the detection area (X,
The light intensity at points C and d, which intersect the boundary line of ; Ys >, is determined, and these 0 and d points are approximated by a straight line.

This approximated straight line is L”=((Ld Lc)/Ys)xY.

...(12°).

Such scanning is performed over the entire detection area (Xs; Ys), and correction values that remove the influence of bright spots are similarly determined and stored for scanning in the Y direction.

Furthermore, the X-direction scanning correction value and the Y-direction scanning correction value are compared point by point for the light i value of the pixel at the same coordinates, and the larger light intensity value as a result of the comparison is stored as the final value at that coordinate. . What is obtained through such comparison becomes an image signal of the detection area (Xs; Ys) from which the bright spot has been removed. The stored value for the detection area (Xs; Y8) portion of the frame memory is replaced with the corrected value obtained by the comparison, and the substituted corrected value is stored in the frame memory 16 as a new corrected image.

Here, by comparing the X-direction scanning correction value and the Y-direction correction value,
The reason why the one with the larger amount of light was selected is that factors that cause measurement errors in measurement, such as the influence of eyelashes and clouding of the crystalline lens, act in the direction of reducing the amount of light. Therefore, the reason is that the one with the larger amount of light is closer to the true value.

Next, the detection area is centered around the center of gravity of the bright spot and sufficiently includes the pupil (
20 (B)), the detection area < ) to find the light intensity distribution on the scanned line. The pupil diameter U is determined from this light amount distribution.

As shown in Figures 14 (A), (B), and (C), the amount of light decreases rapidly when it leaves the pupil and reaches the iris (see Figure 19).
Figure (C)). Therefore, when the rate of change of the light amount distribution γ is determined, the value stands out at the boundary points m and n between the pupil 6 and the iris portion 20. The pupil diameter U can be determined by reading the coordinate positions of the boundary points m and n from the frame memory and calculating them in the arithmetic processing section 17.

In this example, the luminous flux from the light source is not limited and is projected with a sufficiently wide luminous flux, and the luminous flux is limited by the pupil of the examinee's eye, but both the projection system and the light receiving system If a diaphragm smaller than the pupil diameter of a normal person is placed at a position conjugate with the pupil and the light flux is always limited by this diaphragm diameter, it is not necessary to detect the pupil diameter of the eye to be examined. In order to detect the pupil diameter, the light intensity distribution on one scanning line is detected, or if the light intensity distribution is detected over the entire area of the pupil, it is possible to detect the clouding of a transparent body such as the crystalline lens. It is possible to know the location of diseases such as cheilitis.

The detection area (x2; Y2) of the corrected image is scanned in the Y direction (direction perpendicular to the etch), and the light amount distribution on the scanned line is determined.

The scanning lines for determining the light quantity distribution are a plurality of scanning lines passing through the center of gravity of the bright spot, scanning lines -XrpJ, and scanning lines shifted to the +X side (FIG. 21(A)).

Regarding the obtained light intensity distribution, the same -
The average light amount of each pixel of the Fi mark is calculated, and the average value is replaced and stored as a new light amount value of the scanning line passing through the center of gravity of the bright spot (see FIGS. 21(B) and 21(C)).

The light amount distribution obtained by this substitution is shown in FIG. 22, and
Average the light intensity distribution shown in Figure 22 and correct it to the linear measurement light intensity distribution shown in Figure 10.0 As shown in the figure, the □ near the boundary of the pupil is curved, but this is due to the iris etch. It is thought that it is 8 that scatters light. Furthermore, when a subject is dilated with eye drops, there is a phenomenon in which the light intensity level increases near the boundary of the pupil. Therefore, for correction, the portion α near the pupil boundary is removed to obtain a linear measurement light amount distribution. To obtain this measurement light amount distribution, for example, a least squares approximation method is used.

The straight line obtained by this approximation method is shown by 20 in FIG. 22, and Δf/f necessary for calculating the diopter value can be obtained from this straight line Zo. However, the averaged light amount distribution has a drop such as ε due to the influence of eyelashes, clouding of the crystalline lens, etc. Therefore, in order to obtain a more accurate measurement light amount distribution, it is necessary to reduce the influence of this drop ε.

One method is to draw a straight line z as shown in Figure 23.
Based on the straight line Zo', which has a level lower than o by ε',
Values at a lower level than the straight line Zo' (20 in Fig. 22)
(within the range shown by ) is not used as data for approximation, and the straight line Z obtained by further approximation is used as the light amount distribution for measurement.

Alternatively, as shown in Fig. 24, for the range where the level is lower than the 2° line (the range indicated by ε''' in Fig. 24), the averaged light amount distribution is replaced with the value of the line Z0. This is then corrected, approximated by the least squares method using the corrected averaged light amount distribution, and this operation is repeated to obtain the measurement light amount distribution.

Therefore, it is possible to determine the deopter f straightness of the eye to be examined from equations (10) and (11).

The accuracy can be improved by calculating the diopter value for each of multiple image memories and averaging the calculated values.

Although the deopter value for the right eye is determined by the above-described operation, the deopter value for the left eye is also determined by performing the same operation.

When the deopter value is determined, the display 14 displays the area (X, :Y,) of both eyes in FIG. As shown in FIG. 25, the positions of the bright spots determined are superimposed and displayed as the intersections of the orthogonal cross lines 24, and the (X, ,;Y2) area is also displayed in the images of both eyes.

Also, between the areas (XI ; Yi ) of both eyes on the display screen, there is a bright spot or (X2 :Y 2 ) of the removed eyes.
It is read from the area or frame memory 16 and displayed. Furthermore, the (X2; Y 2
) area, the light intensity distribution for measurement, which is the basis for calculating the diopter value 1) (in other words, the light intensity distribution in the direction perpendicular to the etch ridge line (see Figures 23 and 24)) is displayed, and the area The light amount distribution in the direction parallel to the etch ridge line is displayed on the left and right sides of (X,;Y2).

The calculated bright spot position is superimposed and displayed on the captured image, and the corrected image after bright spot removal and the measurement light intensity distribution are displayed simultaneously, allowing the examiner to calculate the bright spot position. As a result, it is possible to judge whether the bright spots have been removed accurately, and the approximate deopter value,
Alternatively, it is possible to grasp the tendency of eye refractive power.

If it is determined that the measurement was not appropriate based on these superimposed and displayed images, it is possible to obtain an appropriate measurement result by starting from capturing the images again.

In the above embodiment, the image of image capture and the image at the time of completion of measurement are displayed on the display, but images of each processing step such as erasing bright spots and displaying light amount distribution for measurement may also be displayed. Of course.

[Effects of the Invention] As described above, according to the present invention, it is possible to check the captured image, so it is possible to check in advance whether the image to be subjected to measurement is appropriate or not, and also to check the measurement results. The suitability of the measurements can also be checked at the time of measurement, ensuring that proper measurement results are obtained, and also avoiding the hassle of having to re-measure due to incorrect measurement results. be able to.

[Brief explanation of drawings]

FIG. 1 is a basic schematic diagram of an eye refractive power measuring device according to the present invention, and FIG. 2 (A), (B), and (fc) are explanatory diagrams showing differences in the state of the light flux due to differences in the diopter value of the eye to be examined. Third
Figures (^) (B) (C) (D) (E) are explanatory diagrams showing the state of light reception and the reflected light flux from the fundus of the subject's eye;
^), Figures 5 (8) and 6 (^) are explanatory diagrams showing the state of the reflected light flux at each point of the light source reaching the light receiving element, and Figure 4 (B
), FIG. 5(B) and FIG. 6(B) are explanatory diagrams showing changes in the light amount of each luminous flux when blocked by a light shielding member, and FIG.
Figures 8 and 9 are explanatory diagrams showing the light quantity distribution state on the light receiving surface corresponding to the diopter value, Figure 10 is an explanatory diagram when calculating the diopter value from the light quantity distribution state, Figures 11 and 12, Fig. 13 is an explanatory diagram showing the change in the amount of light of each light beam when it is blocked by the light blocking member when the spread width Δ on the light blocking member is larger than the size of 172 of the light source, and Fig. 14 (8) is an illustration of a normal eyeball. A diagram showing the state, see FIG. 24) is a diagram showing the light amount distribution in the state, FIG. 24) is a diagram showing the rate of change in light amount before the same, and FIG. 16 is a flowchart in this embodiment, FIG. 17(A) is a diagram of the imaging screen of the eye refractive power measuring device, FIG. 17(B) is an enlarged diagram of the eye to be examined, and FIG. Figure 17 (C) is a diagram showing a bright spot image, Figure 18 is a diagram showing the relationship between the measuring device and both eyes, and Figure 9 (A) is a diagram showing a bright spot image.
), Figure 19 (B) is a diagram showing the range including the bright spot, and Figure 19 (C) is a light intensity distribution map of the scanning line parallel to the edge passing through the bright spot. , Figure 19 (D
) is a light intensity distribution diagram of the scanning line in the direction perpendicular to the etching, Figure 20 (^) is an enlarged view of the eye to be examined similar to Figure 17 (B), and Figure 20 (8) is the scanning area including the pupil. Figure 20 (C) is a diagram showing the light quantity distribution of the scanning line in the direction perpendicular to the etch, and Figure 21 (A) (B) fC) is an explanatory diagram when calculating the averaged light quantity distribution. , Fig. 22 is a diagram showing the relationship between the light amount distribution and the approximate value straight line, Figs. 23 and 24 are explanatory diagrams showing how to obtain the approximate straight line, respectively, and Fig. 25 is a state in which the measurement results are superimposed on the captured image. FIG. 1 is a projection system, 2 is a light receiving system, 3 is an eye to be examined, 4 is a light source, 5 is a half mirror, 18 is an objective lens, 9 is a light receiving element, 13 is a computing unit, 14 is a display, 16 is a frame memory, 17 is a The arithmetic processing section and 18 indicate a control section. Patent applicant Dobcon Co., Ltd.

Claims (1)

[Claims] 1) It has a display section for displaying a pupil image of the subject's eye, and a storage section that positions the subject's eye based on the pupil image of the subject's eye displayed on the display section and stores a still image of the pupil image of the subject's eye. , in an eye refractive power measurement device that measures eye refractive power by calculating a light amount distribution based on a still image stored in the storage unit, the still image stored in the storage unit is displayed on the display unit. An eye refractive power measurement device characterized by: