JP2706251B2 - Eye refractive power measuring device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an eye-refractive-power measuring apparatus that measures refractive power while allowing a subject to observe a fixation target when measuring the refractive power of the eye.

(Prior Art) Generally, the eye refractive power is measured when the eye to be inspected is in a far vision state, that is, when the focus of the eye to be inspected is at infinity.

For this reason, in the conventional eye refractive power measuring apparatus, a parallel light beam is emitted from a point light source which is a fixation target, and the parallel light beam is made incident on the eye to be examined, and the subject gazes at the fixation target. By doing so, the subject's eye is brought into a far vision state.

(Problems to be Solved by the Invention) However, in the above-described eye refractive power measuring device, since the light of the parallel light flux emitted from the point light source is merely incident on the eye to be examined, the eye to be examined is not necessarily in a far vision state. Not necessarily. In particular, when the subject is a child, the subject is distracted and gazing at a place other than the fixation target during the measurement, and the subject's eye does not enter a far vision state. There was a problem that it was not possible to measure.

(Object of the Invention) Accordingly, the present invention has been made in view of the above-mentioned problems, and an eye-refractive-power measuring apparatus capable of measuring an eye-refractive power by allowing an eye to be examined to be naturally in a far-sighted state. The purpose is to provide.

(Means for Solving the Problems) In order to achieve the above object, the present invention displays a fixation target on a fixation display unit and measures the fixation target to the subject when measuring the refractive power of the eye to be examined. An eye-refractive-power measuring apparatus for measuring a refractive power while causing a moving image to be stored, comprising: a moving image storage unit that stores a moving image; and the fixation display using the moving image stored in the moving image storage unit as a fixation target. And an image forming control unit for displaying the moving image, the moving image is composed of a moving image indicating a moving object, and a background image indicating the path of the moving object and indicating the distance, and the size of the moving image Is characterized in that it is made smaller.

(Operation) The moving image stored in the moving image storage unit is displayed as a fixation target on the fixation display unit by the moving image formation control unit. Then, the fixation display unit displays a moving image indicating the moving object, a background image indicating the path of the moving object and showing the distance, and the size of the moving image is small with the background image as the background. Therefore, the moving image looks as if it is moving toward the far side of the route. For this reason, the subject naturally becomes far-sighted by looking at the moving image, and the subject can be surely far-sighted.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a conceptual diagram showing an arrangement of an optical system of an eye refraction measuring apparatus according to the present invention. In FIG. 1, reference numeral 1 denotes a projection optical system for forming a ring-shaped image on a fundus Er of an eye E to be examined. System, 2 is a CCD as a two-dimensional image sensor for the image of the fundus Er
(Image sensor) Image forming optical system for forming on 3
Is a fixation target optical system for fixing the eye E in a far vision state, and 5 is an observation optical system for observing the anterior segment Ea of the eye E. The projection optical system 1 and the illumination optical system 5 correspond to a first optical system, and the imaging optical system 2 corresponds to a second optical system.

The projection optical system 1 includes a perforated mirror 6, an infrared LED light source 7, a relay lens 8, a conical prism 9, a ring-shaped aperture stop 10, a relay lens 11, and an objective lens 21, and the imaging optical system 2 has an objective. Lesbian 21, perforated mirror 6, relay lens
13. Fixing target optical system 4 is composed of CCD3, objective lens 21, infrared transmission visible reflection mirror 14, relay lens 15, fixation display unit
The fixation display unit 16 is composed of a liquid crystal display, a CRT, or the like, and is movable in the direction of the arrow shown in the figure. The anterior ocular segment observation optical system 5 includes an objective lens 21, a half mirror 20, a relay lens 17, an image pickup tube 18, a monitor television 19
Consisting of a ring-shaped aperture stop 10 and fundus Er, CCD3 and fundus Er,
The arrangement relationship of each optical system 1 to 5 and the arrangement relationship of each component are described in JP-A-60-164829, for example, the infrared LED light source 7, the perforated mirror 6, and the pupil Ep of the subject's eye are in a conjugate relationship. Therefore, the detailed description is omitted.

During the measurement, the image of the anterior segment Ea is always displayed on the screen of the monitor TV 19, so that the examiner can appropriately monitor whether the anterior segment Ea is at a predetermined position. Has become.

FIG. 2 is a block diagram showing a signal processing system of the above-mentioned eye refraction measuring apparatus. In the figure, reference numeral 31 denotes an image, for example, as shown in FIG. (Image) An image storage unit that stores images of a predetermined number of frames that travels distantly while traveling on D, and is composed of a ROM, a VTR, or the like. Road D is a background image that also represents perspective. 32 is an image formation control unit that causes the image stored in the image storage unit 31 to be displayed on the fixation display unit,
Reference numeral 41 denotes an A / D converter for converting an image signal output from the image sensor 3 into a digital signal. Reference numeral 43 denotes an image forming optical system 2 which forms an image on the CCD 3 when a target image is projected onto the fundus Er by the projection optical system 1. This is a frame memory for storing image data of a target image to be formed, and sequentially stores digital signals sequentially output from the A / D converter 41 at addresses corresponding to the pixels of the CCD3. Reference numeral 45 denotes a microcomputer which calculates the spherical refraction, astigmatism, and astigmatic axis angle of the eye E from the target image data of the target image stored in the frame memory 43. The microcomputer 45 is an image forming control unit. The control of 32 is performed. 46 is an operation unit for inputting commands and the like for operating the image formation control unit 32; 47 is a storage unit for storing the spherical refraction, astigmatism, and astigmatic axis angle calculated by the microcomputer 45; Is a display unit for displaying the above-mentioned spherical refraction degree, astigmatism degree, astigmatism axis angle, and the like calculated by (1).

Next, the operation of the eye-refractive-power measuring device of the above embodiment will be described with reference to the flowchart of FIG.

In step, the image forming control unit 32 causes the fixation display unit 16
A still image shown in FIG. 3A is displayed, and the subject gazes (fixes) the automobile J. Thereafter, the projection optical system 1
Infrared light is emitted from the LED light source 7. Then, this infrared light is refracted by the conical prism 12, passes through the ring-shaped aperture stop 10, is reflected by the perforated mirror 6, reaches the fundus Er through the objective lens 21, and reaches the fundus Er at the target image. Is formed.

Target image formed on the fundus Er is a ring-shaped image (first ring image R), infrared light forming the primary ring image R ₁ is reflected by the fundus Er, the hole of the perforated mirror 6 Part 6a
Passes through reached the CCD3, secondary ring image R ₂ as an image pattern is formed on the CCD3 as shown in Figure 5.
Then, an image signal corresponding to the amount of light received by each pixel is sequentially output from the CCD 3, and this image signal is converted into a digital signal by the A / D converter 41, and the frame memory corresponding to each pixel is output.
It is stored at the address of 43.

In a step, the target image data stored in the frame memory 43 is read, and in the step, a rough refractive power or a movement amount from a position of the display unit 16 to a conjugate position with the fundus Er is calculated from the data (coarse measurement). And
In the step, the fixation display unit 16
It is moved and adjusted to a position that has a conjugate relationship with Er. By this adjustment, the subject with strong myopia or hyperopia can also see the still image in focus, and the eye E can be surely brought into the far vision state.

In the step, the fixation display unit 16 displays (b) to (b) of FIG.
An image in which the car J travels on the road D and moves far away as shown in (e) is displayed, and the subject naturally sees the eye E in the far vision state by looking at the car. In this way, since the automobile J serving as a fixation table moves to a distant place, even if the subject is a child, interest in the traveling automobile J is invited, and the subject is naturally covered without distraction. The optometry E is brought to the far vision state. In particular, when the subject is easily adjusted by a child or the like, the far point position in the coarse measurement, that is, a position farther than the far point of the subject in a range where the fixation target can be visually recognized instead of the conjugate position with the fundus Er. Then, a moving image may be obtained after cloud fogging. Instead of separately preparing a static image and a dynamic image, a part of the dynamic image may be displayed as a static image without moving as shown in FIG.

The fixation target is not limited to one type, but a plurality of types can be prepared and can be arbitrarily selected by a selection switch (not shown). Although not shown, it is also possible to insert an optical system for correcting astigmatism into the fixation target system, set the value based on the objective result, show the visual acuity chart, and check the corrected visual acuity. In the same manner as in the related art, for example, it is also possible to prepare a static image such as a starburst chart shown in FIG.

Then, in step, the image signal corresponding to the secondary ring image R ₂ formed on CCD3 when the distant state thereof
The image signals are sequentially output from the CCD 3, and the image signals are converted into digital signals by the A / D converter 41 and stored again at the addresses of the frame memory 43 corresponding to each pixel of the CCD 3.

Incidentally, the primary ring image R ₁ and the secondary ring image R ₂ change in size in accordance with the refractive index of the eye E,
It is conventionally known that the eye E has an oval shape when the eye E has astigmatism. Then, the refractive index and the like are obtained from the elliptical shape.

 Here, how to determine the refractive index and the like will be described.

As shown in FIG. 5, in order to determine the coordinates of the ellipse R _3, any point O (X _0, Y ₀₎ with the origin, the point O (X _0, Y ₀₎ and through the horizontal Angle θ with respect to scanning direction H
Is the scanning direction M, and in that direction M, the measurement start point P ₁ and the measurement end point P ₂ are determined in advance.

Here, as determined image pattern is elliptical R ₃ indicated by the two-dot chain line, on the basis of the coordinate points defined as the intersection of the ellipse R ₃ and the scanning direction M, the coordinate points for determining the coefficients of the elliptic equations Must be at least three or more, and thus scan the CCD3 in three or more directions.

Now, the microcomputer 45 reads the image data D of the frame memory 43 stored at the address corresponding to the pixel in the M direction, weights the read image data D, and weights the read image data D in the scanning direction M (P ₁ -P _2). determining the center of gravity position or ring R ₃ and the intersections of the scanning direction M of the image data between). Similarly, three different intersections are obtained. From these intersections, the microcomputer 45 obtains coefficients A, B, and C according to the following equations.

Ax ² + By ² + Cxy = 1 In other words, in FIG. 5, the horizontal scanning direction is regarded as the X axis, the major axis of the ellipse R ₃ is a, the minor axis is b, and the major axis a is X.
Assuming that the angle φ with respect to the axis corresponds to the axis of astigmatism, the major axis a corresponds to the refractive index of the strong main meridian of astigmatism, and the size of the ellipse corresponds to the spherical power, the coefficient A based on the following general formula , B, and C, the refractive powers S, C, and A can be obtained.

That is, if at least three or more coordinate points are detected and their coordinate values are obtained, A, B and C are obtained from the equations by the method of least squares, and if a, b and φ are obtained from the equations, the refractive index can be obtained ( Steps).

Then, in steps, the refractive powers S, C, and A are displayed on the display unit.
It is displayed at 48, and it is determined whether or not the measurement has been completed in a step. If the measurement has not been completed, the process returns to the step. If the measurement has been completed, this routine ends.

In the above-described embodiment, the image of the vehicle moves to a distant place. However, the present invention is not limited to this example.

In the above-described embodiment, the precision measurement is performed after the coarse measurement is performed. However, if the subject is not myopic or hyperopic, the steps (1) to (4) of the coarse measurement may be omitted.

(Effects of the Invention) According to the present invention, the fixation display unit displays a moving image indicating a moving object, a background image indicating the path of the moving object and indicating the distance, and the background image is displayed. Then, the size of the moving image becomes smaller, so that the moving image looks as if it moves toward the far side of the route. For this reason, the subject naturally becomes far-sighted by looking at the moving image, and the subject can be surely far-sighted.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing an arrangement of an optical system of an eye refractive power measuring device according to the present invention, FIG. 2 is a block diagram showing a signal processing system of an objective eye refractive power measuring device, and FIG. Is an explanatory diagram of an image displayed on the fixation display unit, FIG. 4 is a flowchart showing the operation of the microcomputer, FIG. 5 is an explanatory diagram of a ring image formed on the CCD, and FIG. FIG. 4 is a diagram showing a burst chart. DESCRIPTION OF SYMBOLS 1 ... Projection optical system 2 ... Imaging optical system 3 ... CCD 4 ... Fixation target optical system 16 ... Fixation display part 31 ... Image storage part 32 ... Image formation control part 43 ... Frame memory 45 ... Microcomputer E ... Eye to be examined

Claims (2)

(57) [Claims] An eye refractive power measuring apparatus for displaying a fixation target on a fixation display unit and measuring a refractive power while allowing a subject to observe the fixation target when measuring a refractive power of an eye to be examined, A moving image storage unit that stores a moving image; and an image forming control unit that causes the fixed image display unit to display the moving image stored in the moving image storage unit as a fixation target. An eye refractive power measuring apparatus, comprising: a moving image indicating a moving object; and a background image indicating a path of the moving object and indicating a distance, wherein the size of the moving image is reduced. 2. An eye refractive power measuring apparatus according to claim 1, wherein said moving image moves in a background image.