JPH0223934A - Eye refractivity measuring apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an eye refractive power measurement device that objectively measures the eye refractive power of an eye to be examined.

[Prior Art] Conventionally used eye refractive power measuring devices are shown in Figs. 5 to 9.
This will be explained based on the diagram. FIG. 5 is a configuration diagram of a conventional eye refractive power measuring device. In front of the eye E to be examined, there is a measurement index l having a small hole-shaped light transmitting part 1a, and an infrared LE that illuminates the measurement index l.
On a round axis Ll connecting the measurement index 1 and the eye E to be examined, a lens 3 and an optical axis shown in FIG. A projection diaphragm 4 having a circular space 11 4a, a perforated mirror 5 having a hole in the center, and an objective lens 6 are arranged on L1. Note that the perforated mirror 5 is installed at an angle with respect to the optical axis Ll, and is placed equidistantly on the optical axis L2 in the direction of reflection of the light incident from the eye E, centered on the optical axis shown in FIG. a light-receiving diaphragm 7 having three open lower a7b and 7C arranged in the
lens 8, three prisms 9a, 9b shown in FIG.
A deflection prism 9 in combination with 9C and a two-dimensional sensor array 10 such as a COD are arranged in sequence. *: Here, the light-receiving aperture 7 is conjugate with the eye pupil Ep of the eye E to be examined, and the two-dimensional sensor array 10 is arranged in a conjugate plane with the fundus Er.

In such a configuration, the light beam emitted from the measurement target l is formed into an image by the lens 3 between the lens 3 and the objective lens 6, and is further focused by the objective lens 6 into the fundus E of the eye E to be examined.
A spot light beam is projected onto r. Then, the reflected light beam reflected from the fundus Er passes through the objective lens 6, is reflected by the perforated mirror 5, and reaches the light-receiving aperture 7 located at a position conjugate with the eye pupil Ep.

Since the light-receiving diaphragm 7 has three open lower apertures a, 7b, and 7C, it is possible to extract light beams from three locations around the pupil, and the three light beams thus extracted are directed to each of the deflecting prisms 9. It is deflected in a direction away from the optical axis L2 by the corresponding wedge prisms 9a, 9b, and 9C. That is, the light beams that have passed through each of the lower openings a, 7b, and 7C pass through the corresponding wedge prisms 9a, 9b, and 9C, and reach the two-dimensional sensor array 10, as shown in FIG. 0 to form respective spot images A, B, and C on top.
For example, the light beam from the open lower a passes through the cylindrical prism 9a,
Here, it is deflected in a direction perpendicular to the dividing line of the prisms 9b and 9C shown in FIG. The light beams passing through the other open lowers b and 7C are similarly deflected in a direction away from the optical axis L2.

In FIG. 9, the dotted lines and arrows indicate the directions in which the spot images A, B, and C move when the refractive power of the eye E changes.1 When the refractive power changes in the opposite direction, the spot images A,
B and C will shift in the opposite direction to the arrow, and if there is astigmatism, they will shift away from the dotted line. To determine the refractive power of the eye E, first the two-dimensional coordinates of the spot images A, B, and C are determined. If the two-dimensional sensor array 10 is an image sensor of a television camera, the video signal may be used, and an appropriate threshold level may be determined by an electric circuit such as an image processing circuit or an arithmetic processing circuit, and a binary value may be generated. turned into
Find the spot center position by calculation. Furthermore, signals for each element can also be used to obtain accurate values. After calculating the coordinates by binarizing or multi-valued, the eye refractive power is calculated from the coordinates.

The refractive power of the eye consists of three values: spherical power, astigmatic power, and astigmatic power, and the change in the radial direction is assumed to be sinusoidal, so once the refractive value of the two radial lines is determined, the rest is done by calculation. It can be calculated.

However, in the above-mentioned conventional measuring device, since there is no means for moving the measurement index l in the direction of the optical axis L1, when the eye E to be examined is close to emmetropia, the projected image of the measurement index 1 on the fundus Er is clear. However, in the case of severe myopia, hyperopia, or aphakic eyes, this projected image becomes significantly blurred.
There is a risk that the S/N ratio of the projected image will decrease and the measurement accuracy will deteriorate.

[Object of the Invention] The object of the present invention is to eliminate the above-mentioned drawbacks, first detect the state of the refractive power of the eye to be examined, and move the measurement index substantially in the optical axis direction according to this state, thereby detecting severe myopia. An object of the present invention is to provide an eye refractive power measuring device that can improve measurement accuracy by forming an index projection image with less blur on the fundus of an eye to be examined, such as hyperopia, aphakia, and the like.

[Summary of the Invention] The gist of the present invention for achieving the above-mentioned object is to project a measurement index onto the fundus of an eye to be examined, detect a projected image of the fundus of the measurement index, and objectively measure the eye refractive power. In the eye refractive power measurement device, a first measuring means for measuring the refractive power of the eye to be examined by arranging the measurement index at a predetermined position or an arbitrary position;
This eye refractive power measuring device is characterized by comprising a second measuring means for measuring refractive power by moving the measuring index substantially in the optical axis direction according to the result of the measuring means.

[Embodiments of the Invention] The present invention will be described in detail based on embodiments illustrated in FIGS. 1 to 4.

FIG. 1 is a configuration diagram of an eye refractive power measuring device, and the same reference numerals as in the conventional example in FIG. 5 indicate the same members. The output of the two-dimensional sensor array 10 is connected to an arithmetic processing circuit 11,
The output of the arithmetic processing circuit ll is a drive device 1 consisting of a motor etc.
2, the measurement index l and the light source 2 are configured to be movable in the direction of the optical axis L1.

When a measurement switch (not shown) is pressed after a predetermined position has been set for the eye E to be examined, the measurement index l first performs a preliminary measurement at the initial position, for example, the measurement position when the eye E to be examined is emmetropic. In the measurement, the approximate eye refractive power of the eye E to be examined is measured, and the arithmetic processing circuit 11 processes the measured value and sends a drive signal to the drive bag 2112, and the drive device 12 places a measurement index 1 on the fundus Er of the eye E to be examined. The measurement position of the measurement index 1 is controlled so that the image of the measurement index 1 is clearly formed. It is possible to measure the refractive power of the eye.

Here, it is preferable that the time from the preliminary measurement to the actual measurement be as short as possible, and a means for detecting that the eye E to be examined is in a predetermined position is provided so that the examiner does not press the measurement switch. Once the position of the eye E to be examined is confirmed by this detection means, the preliminary measurement to the main measurement may be performed automatically. There is no problem with movement.

FIG. 2 shows a configuration diagram of a second embodiment of the present invention, in which the measurement index l is fixed instead of moving as in the first embodiment, and the distance between the measurement index 1 and the lens 3 is The focusing lens 13 is inserted onto the optical axis L1, and the focusing lens 13 is moved onto the optical axis L using the driving device 12' which is activated by the output of the arithmetic control circuit 11 according to the result of preliminary measurement.
It is configured to move in one direction, focus on the fundus Er of the eye E to be examined, and take a projected index image with less blur.

FIG. 3 shows the configuration of a third embodiment of the present invention, and a rotary disk 14 with lenses in which a plurality of lenses 14a having different focal lengths are fitted along the circumference as shown in FIG. The driver 12'' is used to rotate the lens 14a on the optical axis L1 according to the result of the preliminary measurement 4a, and the index projected image is projected onto the fundus Er of the subject [H]. I try to project images with less blur.

[Effects of the Invention] As explained above, the eye refractive power measuring device according to the present invention has the following effects:
First, a preliminary measurement is carried out, and the position of the measurement index on the optical axis is substantially changed according to the results obtained in this preliminary measurement, so that even in eyes with severe myopia or hyperopia, there is no blur in the fundus. It becomes possible to project a small number of images, and the electrical S
Since an image with a good /N ratio can be obtained, accurate measurements can be made in the next main measurement.

[Brief explanation of the drawing]

1 to 4 show embodiments of the eye refractive power measuring device according to the present invention, and FIGS.
．． FIG. 4 is a configuration diagram of second and third embodiments. Fig. 4 is a front view of a rotating disk with a lens, Fig. 5 is a configuration diagram of a conventional measuring device, Fig. 6 is a front view of a projection diaphragm, Fig. 7 is a front view of a light receiving diaphragm, and Fig. 8. 9 is a front view of the deflection prism, and FIG. 9 is an explanatory diagram of a spot light beam on the two-dimensional sensor array. Reference numeral 1 is a measurement index, 2 is a light source, and 4 is a projection aperture. 5 is a perforated mirror, 6 is an objective lens, 7 is a light receiving aperture, 9
is a prism, and 10 is a two-dimensional sensor array. 11 is an arithmetic processing circuit, 12 is a drive device, 13 is a focusing lens, and 14 is a rotating disk with a lens. Patent applicant: Canon Co., Ltd. N1, M2, Ugly, 3

Claims (1)

[Claims] 1. In an eye refractive power measurement device that projects a measurement index onto the fundus of the eye to be examined, detects a projected image of the fundus of the measurement index, and measures eye refractive power objectively, the measurement index is placed at a predetermined position or at an arbitrary position. a first measuring means disposed in the eye to measure the refractive power of the eye to be examined; and a first measuring means disposed in the eye to measure the refractive power by moving the measuring index substantially in the optical axis direction according to the result of the first measuring means. 1. An eye refractive power measuring device characterized by comprising: 2 measuring means.