JP2002360516A - Ophthalmological device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely obtain the optical characteristic of an eye to be examined such as a diopter, corneal curvature radius or the like. SOLUTION: A ring image R obtained by an imaging device is allocated to two-dimensional coordinates, data in horizontal and vertical direction to the coordinates is read in order and data in the direction of a straight line having inclination capable of designating only the integral part of the two-dimensional coordinates is also read in order. Thus, the ring image R can be detected and even when the detected ring image R receives influence from eyelashes, etc., around the eye to be examined, the diopter, the corneal curvature radius, etc., of the eye to be examined can precisely be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ophthalmic apparatus such as an auto-refractometer for measuring a fundus reflection image of a measurement index to obtain an eye refractive power and a keratometer for measuring a corneal reflection image of a measurement index to obtain a corneal curvature radius. It is about.

[0002]

2. Description of the Related Art Conventionally, when a ring index is used as an index for measurement, the index is projected on the fundus or cornea of an eye to be examined, and when a reflected image is captured by a sensor, the shape of the captured ring image is obtained. Sometimes. In this case, in order to process the sampled matrix-like discrete data, scanning is performed in the horizontal and vertical directions, the calculated data is approximated to an ellipse, and the eye refractive power and the corneal curvature radius of the eye to be examined are obtained.

[0003] Further, as disclosed in Japanese Patent No. 20221697, a method is also known in which scanning is performed from the center of a ring image outward at regular angle intervals, and the calculated data is approximated to an ellipse to obtain a refractive power and a corneal curvature radius. I have.

[0004]

However, in the above-mentioned conventional example, in the method of scanning in the horizontal and vertical directions,
Although no complicated circuit is required, only the horizontal and vertical portions of the ring image are detected. For this reason, when highly reliable data in a portion close to horizontal or vertical is not detected as the ring image R due to lack of the ring image R as shown in FIG. May lower the reliability of the calculation result.

Further, in the method of scanning at regular intervals, it is difficult to be affected by eyelashes and the like around the eye to be examined. However, a complicated circuit is required, and unless a calculation including a decimal part of two-dimensional coordinates is performed. Accumulated errors in coordinates cannot be avoided, which leads to an increase in the calculation time and a higher cost than in the above method.

An object of the present invention is to solve the above-mentioned problems,
Provided is an ophthalmologic apparatus capable of reducing the processing time and cost without requiring a complicated circuit while reducing the influence of eyelashes and the like around the eye to be examined when obtaining the eye refractive power and the corneal curvature radius. Is to do.

[0007]

According to the present invention, there is provided an ophthalmologic apparatus for achieving the above object, comprising: index projecting means for optically projecting an index for detecting eye information to be inspected; Imaging means for imaging the reflected image of the, the captured index image is allocated to two-dimensional coordinates, the data is sequentially read by scanning in a linear direction having a slope that can be specified only integer part with respect to the coordinates, Calculating means for detecting the index image.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the embodiments shown in FIGS. FIG. 1 shows a configuration diagram of the embodiment. On the transmission optical path O1 of the dichroic mirror 1 in front of the eye E, an objective lens 2 for measuring an eye refractive power, a perforated mirror 3, a projection stop 4, a projection lens 5,
An index plate 6 and an eye-refractive-power measuring light source 7 that emits near-infrared light are arranged to constitute an eye-refractive-power measuring light projection system.

In the direction of reflection of the dichroic mirror 1,
An objective lens 8 for observing the anterior eye, a dichroic mirror 9 and a mirror 10 are arranged. Optical path O2 in the reflection direction of mirror 10
A fixation target projection system for fixation by an eye (not shown) is arranged on the upper side.

On the optical path O3 in the reflection direction of the dichroic mirror 9, an imaging lens 11 and an image pickup device 12 such as a CCD camera are arranged at a position substantially conjugate with the vicinity of the anterior segment of the eye E to be examined.

A ring aperture 13, a conical prism 14, a relay lens 15, and an image pickup device 16 such as a CCD camera are arranged outside the optical axis in the reflection direction of the perforated mirror 3 to constitute an eye refractive power measurement light receiving system. I do.

Further, in front of the anterior segment of the eye E, an anterior segment illumination light source 17 such as an LED that emits near-infrared light having a wavelength several tens of nm shorter than the eye refractive power measurement light source 7 and an eye to be examined A ring light source 1 such as an LED emitting near-infrared light for projecting a ring target for measuring a corneal shape on the cornea Ec of E
8 to form an anterior ocular segment observation system.

The dichroic mirror 1 transmits most of the light having the wavelength emitted from the eye-refractive-power measuring light source 7, reflects part of the light, and reflects light having the wavelength emitted from the anterior segment illumination light source 17. The dichroic mirror 9 has a characteristic of transmitting visible light and reflecting near-infrared light.

The above-mentioned observation system, fixation target projection system, eye refraction power measuring light projection system, eye refraction power measuring light receiving system, etc. constitute an eye examination part to be examined, which is not shown. It is mounted on a gantry that can move in three axial directions, and the examiner can operate the operating rod to move the eye examination section freely. The gantry and the operating rod It constitutes a positioning means.

FIG. 2 is a block circuit diagram. The imaging devices 12 and 16 are connected to A / D converters 20 and 21, respectively, and their outputs are stored in image memories 22 and 23, respectively.
And an arithmetic processing unit 2 for controlling all the devices.
Connect to 4. In addition to the above, the arithmetic processing unit 24 includes an operation unit 25 for operating the eye refractive power measurement light source 7 and the eye examination unit,
A television monitor 27 is connected via a D / A converter 26.

The luminous flux from the light source 7 for measuring the refractive power of the eye is
Projection spot 5, shooting aperture 4,
The light is projected onto the fundus Er of the eye E through the perforated mirror 3, the objective lens 2, and the dichroic mirror 1, and the reflected light is reflected by the perforated mirror 3, and is formed into a ring shape using the ring diaphragm 13 and the conical prism 14. The ring image is imaged by the image sensor 16.

FIG. 3 shows a ring image R picked up on the image pickup device 15. By approximating the ring image R with an ellipse, the eye refractive power of the eye E can be obtained. The captured image data is converted by the A / D converter 21 as data of each pixel of the image sensor 16 into the image memory 2.
3 and stored.

As a method of elliptic approximation, image data stored in the image memory 23 is allocated to two-dimensional coordinates corresponding to pixels in the horizontal direction H and the vertical direction V, and the center of the two-dimensional coordinates is (Hc, Vc). I do.

First, data is read out in the horizontal direction, and from the point at the center (Hc, Vc), the data is added to Hc one by one to perform the calculation, thereby obtaining the data shown in the graph of FIG. An arbitrary threshold level TL is determined, the center of gravity is calculated using data on a scanning line larger than the threshold level TL, and the coordinates of the center of gravity are used for elliptic approximation. This time, Hc is decremented by one, an operation is performed, and the same processing is performed.

Next, an arbitrary step S is added to Vc.
The calculation is performed in the horizontal direction from the point (Hc, Vc + S), and the same processing as described above is performed. (Hc, Vc + 2S), (H
c, Vc + 3S), (Hc, Vc + 4S),..., and proceed to the setting (Hc, Vc + aS). Next, in the horizontal direction from the point (Hc, Vc−S) obtained by subtracting S from Vc. Calculate and process. Similarly, the setting (Hc, Vc-a
The calculation is performed up to S).

Second, data is read out in the vertical direction. As shown in FIG. 5, from the center (Hc, Vc) point, V
The arithmetic operation is performed by adding and subtracting one from c each time, and the barycentric coordinates are obtained from the data on the scanning lines in the same manner as in the horizontal operation. Hc
And an arbitrary step S is added to (Hc + S, Vc),
(Hc + 2S, Vc), (Hc + 3S, Vc),.
・ Calculate in the vertical direction from the point of (Hc + aS, Vc),
A process for obtaining the barycentric coordinates is performed. (Hc-S, Vc),
(Hc-2S, Vc), (Hc-3S, Vc), ...
.., (Hc−aS, Vc).

Third, data is read in a direction having an inclination as shown in FIGS. First, referring to FIG. 6, from the point at the center (Hc, Vc), Hc is incremented by 1 and Vc is decremented by 1. Also, Hc
Is subtracted one by one, and one is added to Vc for calculation. The barycentric coordinates are obtained from the data on the scanning line. Further, an arbitrary step S is added to Hc and Vc, and (Hc + S, Vc
+ S), (Hc + 2S, Vc + 2S), (Hc + 3S,
Vc + 3S),..., (Hc + aS, Vc + aS) are calculated in a direction having an inclination, and a process of obtaining the barycentric coordinates is performed, and (Hc−S, Vc−S), (Hc−2S, V
c-2S), (Hc-3S, Vc-3S), ...
.., (Hc-aS, Vc-aS).

Referring now to FIG. 7, calculation is performed by adding 1 to each of Hc and Vc from the center (Hc, Vc). In addition, Hc and Vc are each 1
Subtraction is performed for each operation. The barycentric coordinates are obtained from the data on the scanning line. Also, an arbitrary step S is added to Hc,
An arbitrary step S is subtracted from Vc, and (Hc + S, Vc−
S), (Hc + 2S, Vc-2S), (Hc + 3S, V
c−3S),..., (Hc + aS, Vc−aS), a calculation is performed in a direction having an inclination to obtain a barycentric coordinate, an arbitrary step S is subtracted from Hc, and an arbitrary step is subtracted from Vc. Step S is added, and (Hc−S, Vc + S),
(Hc-2S, Vc + 2S), (Hc-3S, Vc + 3
S),..., (Hc−aS, Vc + aS).

As described above, by performing an operation on the data in the direction having the inclination, sufficiently reliable operation results can be obtained even on the data on the ring position in the direction having the inclination, thereby improving the measurement accuracy. Can be done. Further, even when a ring image serving as an index image for measurement is missing due to the influence of eyelashes or the like around the eye to be examined, measurement accuracy can be improved.

As shown in FIG. 8, the detection ranges of the center-of-gravity data in the first direction are a1 and a2, and the detection range is set to 45 ° so as not to overlap the scanning in the second and third directions. The number of data detected at a1 and a2 is Na. Second
The detection ranges of the centroid data in the directions are b1 and b2, and the number of detected data is Nb. The detection ranges of the center-of-gravity data in the third direction are c1 and c2, and d1 and d2, respectively. The numbers of detected data are Nc and Nd.

As shown in FIG. 9, ellipse approximation is performed by using the least squares method, using all the barycentric coordinate data obtained by the data calculations in the first, second, and third directions. This allows
From the obtained ellipse, the measured refractive power, astigmatism, and astigmatic axis angle of the eye to be examined are determined.

When an actual measurement is performed, there are a preliminary measurement of cloud fog and the like and a main measurement for obtaining a measured value. At the time of preliminary measurement,
In order to reduce the processing time, only the first and second horizontal and vertical data calculations are performed, and at the time of the main measurement, the first, second, third horizontal, vertical and tilt data calculations are performed.

In this embodiment, measurement of the eye refractive power of the eye E has been described. However, a similar method can be used for measurement of the corneal curvature radius. Corneal shape measurement ring light source 18
Is projected onto the cornea Ec of the eye E to be examined, and a ring image, which is the reflected light, is imaged by the image sensor 12.
The corneal curvature radius of the eye E is obtained by approximating the ring image with an ellipse.

The captured image data is transferred to the image memory 22 by the A / D converter 20 as data of each pixel of the image sensor 12 and stored. The ellipse approximation method can improve the measurement accuracy of the corneal curvature radius by using the same method as described above.

[0030]

As described above, the ophthalmologic apparatus according to the present invention guarantees the accuracy of the entire circumference of the ring image even when the ring image serving as the index image for measurement is lacking due to the influence of eyelashes around the eye to be examined. It becomes possible to make the eye refractive power, the corneal curvature radius, and the like of the eye to be inspected less affected by eyelashes and the like around the eye to be inspected.

Further, the ophthalmologic apparatus according to the present invention can perform data calculation only at a specific angle by performing such data calculation. Processing can be performed using only the integer part of the dimensional coordinates, which leads to a reduction in processing time.

[Brief description of the drawings]

FIG. 1 is an optical system configuration diagram of the present embodiment.

FIG. 2 is a block circuit configuration diagram.

FIG. 3 is an explanatory diagram of horizontal scanning.

FIG. 4 is a graph of a ring image light amount distribution on a scanning line.

FIG. 5 is an explanatory diagram of vertical scanning.

FIG. 6 is an explanatory diagram of scanning in a direction having a first inclination.

FIG. 7 is an explanatory diagram of scanning in a direction having a second inclination.

FIG. 8 is an explanatory diagram of a detection range for obtaining barycenter data.

FIG. 9 is an explanatory diagram of an image from image input to ellipse approximation.

FIG. 10 is an explanatory diagram of a ring image when affected by eyelashes.

[Explanation of symbols]

 1, 9 Dichroic mirror 8 Objective lens for anterior ocular segment observation 11 Imaging lens 12, 16 Image sensor 2 Objective lens for eye refractive power measurement 3 Perforated mirror 4 Projection stop 6 Indicator plate 7 Eye refractive power measurement light source 13 Ring stop 14 Conical prism 17 Anterior segment illumination light source 18 Corneal shape measurement ring light source 20, 21 A / D converter 22, 23 Image memory 24 Arithmetic processing unit 26 D / A converter 27 TV monitor 25 Operation unit

Claims (3)

[Claims] 1. An index projecting means for optically projecting an index for detecting eye information to be inspected, an imaging means for imaging a reflection image of the index from the eye to be inspected, and a two-dimensional coordinate And an arithmetic unit for sequentially reading data by performing scanning in a linear direction having an inclination that can be specified only with an integer part with respect to the coordinates, and detecting the index image. . 2. The method according to claim 1, wherein the calculating means reads out the data in the linear direction having the inclination and sequentially reads out the data in the horizontal or vertical direction of the two-dimensional coordinates, thereby detecting the index image. The ophthalmic apparatus according to claim 1, wherein: 3. The ophthalmologic apparatus according to claim 1, wherein the arithmetic unit performs a centroid operation on the data read in each direction.