JP2004236847A - Ophthalmologic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform an alignment of an ophthalmologic device accurately and quickly. <P>SOLUTION: In S1, coordinates of three bright spots of a cornea reflected image are detected from an image of an anterior portion of an eye taken by a two-dimensional image pickup device. In S2, the diameter of the pupil is acquired from the three bright spots detected in S1. The process shifts to S3 wherein the diameter of the pupil which is computed in S2 is determined and the process shifts to S4 when the computed diameter of the pupil is 4mm or below or to S6 when it is beyond 4mm. In S4, a position of the center of gravity of the pupil is calculated and the center of the pupil is acquired. In S5, an eccentricity amount of the alignment in the XY direction between the center of the pupil and a measuring beam axis is computed, then the process shifts to S7. In S7, the eccentricity amount of the alignment in the Z direction is acquired by the eccentricity of the X coordinates of the upper and lower bright spots in the cornea reflected image detected in S1. In S8, the eccentricity amount in each X, Y and Z direction is determined to be within a prescribed range or not, and when it is beyond the prescribed range, the process shifts to S9 wherein the eccentricity amount is decreased by driving a motor according to the eccentricity amount, then the process shifts back to S1. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an ophthalmologic apparatus that automatically positions a subject's eye and an optometry unit.
[0002]
[Prior art]
As a method of aligning with a subject's eye in a conventional eye refraction power measuring device that projects a measurement light beam to a pupil of the subject's eye and performs an examination using reflected light from the fundus, the position is adjusted to a vertex of a cornea of the subject's eye. I have. Depending on the eye to be examined, the pupil and the cornea apex may be eccentric, and if the eccentricity is large, the luminous flux required for measurement is eclipsed by the iris, and it may be difficult to obtain a correct measurement value.
[0003]
In addition, accurate measurement of refractive power is more accurate when measured at the center of the pupil, which is the original visual axis, and the measurement optical axis is aligned with the center of the pupil as described in JP-A-9-66027. A device for performing the above is known.
[0004]
[Problems to be solved by the invention]
However, in the above-described conventional example, when the pupil of the eye to be examined is large, the eyelid easily covers the pupil region. With such a simple calculation, it is difficult to accurately determine the center position of the pupil, and there is a possibility that the measurement may be performed at a position different from the center of the pupil.
[0005]
Further, there is a problem that the detection position of the center of the pupil is not constant depending on how the eyelids cover the pupil region, the position to be measured changes every measurement, and the measurement value is not stable. Furthermore, in order to accurately obtain a pupil stop in a state in which the eyelids are over the pupil region, complicated calculations are required, and the calculation time becomes longer and the measurement time becomes longer, which places an extra burden on the subject. There are also problems.
[0006]
An object of the present invention is to solve the above-mentioned problems and to provide an ophthalmologic apparatus capable of performing accurate and quick alignment and measurement.
[0007]
[Means for Solving the Problems]
An ophthalmologic apparatus according to the present invention for achieving the object described above projects a light beam into a pupil of an eye to be inspected, and in a ophthalmologic apparatus that performs measurement or inspection using reflected light, a light beam for alignment is applied to a cornea of the eye to be inspected. Alignment light projecting means for projecting light; detecting means for detecting a corneal reflection light flux of the alignment light flux to detect the position of the corneal vertex; imaging means for photographing the anterior segment of the subject's eye; and output from the imaging means Calculating means for calculating the center position and pupil diameter of the pupil of the eye to be examined based on the signal; and a corneal vertex detected by the detecting means if the pupil diameter of the eye to be calculated calculated by the calculating means is larger than a predetermined value. The position of the optometry unit is adjusted to an appropriate position by detecting a position shift between the position and the optometry unit, and when the pupil diameter of the eye to be calculated calculated by the calculation unit is smaller than a predetermined value, the calculation unit Arithmetic It was to detect the positional deviation of the pupil center and the eye portion of the eye, and having a control means for aligning the ophthalmic examination unit in the proper position.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
The present invention will be described in detail based on the illustrated embodiment.
FIG. 1 shows an external view of an eye refraction measuring apparatus, in which an optometry unit 2 is movably mounted on a base 1 and an operation surface of the base 1 is provided with measurement values, images of an eye to be examined, and the like. A display unit 3 including a liquid crystal monitor and a CRT monitor for selecting display and setting of various devices; a trackball 4 and a roller 5 for operating the display screen and roughly aligning the optometric unit 2 with the eye to be inspected; A switch panel 6 on which a printer print switch, a measurement start switch, a selection setting switch, and the like are arranged, and a printer 7 for printing a measurement result are arranged. The subject can measure by placing his / her face on a face receiving unit (not shown) on the opposite side of the operation surface of the base 1 and placing the subject's eye in front of the objective unit of the optometric unit 2.
[0009]
FIG. 2 shows an optical configuration diagram of the inside of the optometry unit 2. On the optical axis O of the optometry unit 2 aligned with the visual axis of the eye E, visible light is totally reflected from the eye E side. A dichroic mirror 11, an objective lens 12, a perforated mirror 13, an aperture 14, a projection lens 15, a projection aperture 16, and a measurement light source 17 which emits an 880 nm light beam are sequentially arranged. . In the reflection direction of the perforated mirror 13, a six-segment stop 18, a six-segment prism 19, a light receiving lens 20, and a two-dimensional image sensor 21 are sequentially arranged. The six-segment diaphragm 18 and the six-segment prism 19 have the shapes shown in FIG. 3, and the six-segment diaphragm 18 and the six-segment prism 19 are actually in close contact.
[0010]
On the other hand, in the reflection direction of the dichroic mirror 11, a fixation target projecting optical system and a light receiving optical system that shares anterior eye observation and alignment detection are arranged. As a light receiving optical system, a lens 22, a dichroic mirror 23, an alignment prism stop 24, an imaging lens 25, and a two-dimensional image sensor 26 are sequentially arranged. The alignment prism aperture 24 has a shape as shown in FIG. 4, and a disk-shaped aperture plate is provided with three openings in a row, and the apertures on both sides of the dichroic mirror 23 have only a wavelength of about 880 nm. Alignment prisms 24a and 27b transmitting the light beam are adhered.
[0011]
As a fixation projection optical system, a total reflection mirror 27, a fixation guide lens 28, a fixation chart 29, and a fixation projection light source 30 are sequentially arranged on the transmission side of the dichroic mirror 23. External eye illumination light sources 31a and 31b are provided on both sides of the optical axis O in front of the subject's eye E.
[0012]
FIG. 5 is a block circuit diagram of the eye refraction measuring apparatus. The trackball 4, the roller 5, the switch panel 6, and the printer 7 are connected to the CPU 41 which performs control and calculation. The CPU 41 is connected with a vertical drive motor 42, a front-rear drive motor 43, and a left / right drive motor 44 for driving the optometry unit 2 via motor drivers 45, 46, and 47, respectively. Further, the fixation target light source 30, the external eye illumination light source 31, and the measurement light source 17 are connected to the CPU 41 via a D / A converter 48, and a fixation guidance lens motor 49 for driving the fixation guidance lens 28 is provided. It is connected via a motor driver 50.
[0013]
The outputs of the two-dimensional imaging devices 21 and 26 are connected to a video switch 51, and the output of the video switch 51 is branched. One is connected to the CPU 41, and the other is connected to the CPU 41 via the A / D converter 52 and the image memory 53. ing. The output of the two-dimensional image sensor 21 is combined with a signal from the CPU 41 via the character generator 54 and connected to the display unit 3.
[0014]
In the eye refraction measuring apparatus configured as described above, first, the operator places the face of the subject on the face cradle, and then adjusts the optical axis O of the optometry unit 2 with respect to the eye E by using a track. The ball 4 and the roller 5 are operated. The operation of the trackball 4 moves the optometry unit 2 in the left-right and front-rear directions with respect to the eye E to be examined, and the roller 5 can move the optometry unit 2 in the up-down direction to perform positioning.
[0015]
In this operation, the CPU 41 receives output signals from the respective pulse counters and rotary encoders incorporated in the trackball 4 and the roller 5 on the apparatus side, and can detect the operation amount and speed. Further, the up / down drive motor 42, the front / rear drive motor 43, and the left / right drive motor 44 are driven via the motor drivers 45, 46 and 47 based on the operation amount and speed.
[0016]
At the time of fixation guidance, the illuminated projection light flux of the illuminated fixation projection light source 30 illuminates the fixation chart 29 from behind, and is projected to the fundus Er of the eye E through the fixation guidance lens 28 and the lens 22. The fixation guide lens 28 is moved in the optical axis direction by rotation of the fixation guide lens motor 49 so as to be able to cope with a change in the diopter of the eye E to be inspected.
[0017]
The light source for alignment detection is shared with the measurement light source 17, the light beam from the measurement light source 17 is reflected by the cornea Ec of the eye E, and the corneal reflection light beam is reflected by the dichroic mirror 11 and passes through the lens 22. The light is reflected by the dichroic mirror 23 and guided to the alignment optical system. In the alignment optical system, the light beam transmitted through the alignment prism 24a of the alignment prism stop 24 is refracted downward, and the light beam transmitted through the alignment prism 24b is refracted upward. The light beam passing through the central opening is transmitted as it is, and forms three bright spots on the two-dimensional image sensor 26 via the imaging lens 25.
[0018]
Further, the anterior segment image of the eye E and the corneal reflection images of the external eye illumination light sources 31a and 31b having a wavelength of 880 nm are also reflected by the dichroic mirror 11, pass through the lens 22, and are further reflected by the dichroic mirror 23 to the alignment optical system. The light is guided, passes only through the central opening of the alignment prism stop 24, and is imaged on the two-dimensional image sensor 26 via the imaging lens 25.
[0019]
A video signal of an anterior segment image captured by the two-dimensional image sensor 26 is converted into digital data by an A / D converter 52 via a video switch 51 and stored in an image memory 53. The CPU 41 performs image processing such as extraction of an alignment bright point and pupil extraction based on the image stored in the image memory 53. In addition, the video signal of the anterior segment image captured by the two-dimensional image sensor 26 is combined with a signal from the character generator 54 to display the anterior segment image, measured values, and the like on the display unit 3. Further, the measured values and the like are printed on the printer 7 as necessary.
[0020]
FIG. 6 is an explanatory diagram of a screen of the display unit 3, and shows an anterior eye image of the eye E to be inspected by the two-dimensional image sensor 26. The anterior eye image of the eye E and the corneal reflection images of the extraocular illumination light sources 31a and 31b are formed on the left and right sides of the pupil image by a light beam transmitted through the center opening of the alignment prism stop 24. In addition, a corneal reflection image from the measurement light source 17 is also formed as three bright points in one vertical line. That is, the light beam transmitted through the alignment prism 24a of the alignment prism stop 24 becomes an upper bright point, the light beam transmitted through the alignment prism 24b becomes a lower bright point, and the light beam transmitted through the center opening becomes a central bright point.
[0021]
FIG. 6A shows a state where the working distance of the eye E is properly aligned, and FIG. 6B shows a state before the working distance between the eye E and the optometry unit 2 is longer than the proper position. FIG. 6C illustrates an anterior eye image in a state where the working distance between the eye E and the optometric unit 2 is shorter than an appropriate position. The alignment deviation in the working distance direction of the alignment is calculated based on the deviation of the X coordinate of the upper and lower bright points, and the alignment deviation in the vertical and horizontal directions is calculated based on the position of the central bright point.
[0022]
The operator moves the optometry unit 2 by the above-described operation, and moves the eye examination unit 2 to a certain position so that three bright spots due to the corneal reflection light of the alignment light can be seen on the cornea Ec of the eye E through the display unit 3. When the three bright spots are confirmed on the display unit 3 by performing the alignment, the automatic alignment is started by pressing a measurement start switch arranged on the switch panel 6.
[0023]
FIG. 7 is a flowchart of the automatic alignment. First, in step S 1, a video signal of an anterior segment image of the eye E to be inspected captured by the two-dimensional image sensor 26 is converted into a digital signal via the A / D converter 52. The data is converted into data, captured into the image memory 53, and the CPU 41 extracts three bright points of the corneal reflection image by the measurement light source 17 from the anterior eye image in the image memory 53, and detects the coordinates of each bright point.
[0024]
FIG. 8 shows an anterior segment image of the eye E to be inspected captured in the image memory 53. In step S2, Y of the central bright spot B1 of the three bright spots of the corneal reflection image detected in step S1. In the horizontal line Ly on the coordinates, the edges E1 and E2 of the pupil P and the iris are detected, the distance ΔX between the edges E1 and E2 is calculated, and the pupil diameter of the pupil P of the eye E is calculated from the distance ΔX. .
[0025]
Next, the process proceeds to step S3, the size of the pupil diameter of the pupil P calculated in step S2 is determined, and if the pupil diameter is, for example, 4 mm or less, the process proceeds to step S4, and if the pupil diameter is 4 mm or more, the process proceeds to step S6. Transition.
[0026]
In step S4, the position of the center of gravity of the pupil P is calculated from the anterior segment image of the eye E captured into the image memory 55, and the center of the pupil is obtained. Subsequently, in step S5, the amount of misalignment between the center of the pupil and the measurement optical axis of the apparatus in the left, right, up and down XY directions is calculated, and the process proceeds to step S7.
[0027]
When it is determined in step S3 that the pupil diameter is larger than 4 mm, in step S6, the measurement optical axis of the apparatus is calculated from the coordinates of the center bright spot B1 of the three corneal reflection images detected in step S1. Then, the shift amount of the alignment in the X and Y directions is calculated, and the process proceeds to step S7. In step S7, the amount of misalignment in the Z direction, which is the working distance, is determined by the displacement of the X coordinate of the upper and lower bright points B2 and B3 of the corneal reflection image detected in step S1.
[0028]
In step S8, it is determined whether or not the amount of displacement in each of the X, Y, and Z directions is within a predetermined range. If the amount of displacement is larger than the predetermined range, the process proceeds to step S9. The front / rear drive motor 43 and the left / right drive motor 44 are driven to reduce the misalignment, and the process returns to step S1.
[0029]
The steps described above are repeated until it is determined in step S8 that the deviation amount is within the predetermined range, and after the automatic alignment operation is completed, a measurement operation is performed to calculate a measured value.
[0030]
The reason why the alignment detection method in the XY directions is switched according to the pupil diameter in step S3 will be described. FIG. 9A shows an anterior eye image in a state where the pupil diameter of the eye E is small and the eyelids are lowered, and FIG. 9B is a diagram in which the pupil diameter of the eye E is large and the eyelids are lowered. 5 shows an anterior eye image in a state where the camera is in an occupied state. When the pupil diameter is small as shown in FIG. 9A, the eyelid does not cover the pupil region even if the eyelid is slightly lowered, so that the original center Pg of the pupil and the calculated center Pg ′ of the pupil P are almost equal. Matches.
[0031]
However, as shown in FIG. 9B, when the pupil diameter is large, even if the eyelid is slightly lowered, the eyelid covers the pupil region. If the center of gravity of the pupil P is obtained in such a state, the calculated pupil center will be displaced from Pg ′ and the original pupil center Pg.
[0032]
Further, since this shift changes depending on the amount of the eyelid covering the pupil region, measurement cannot be performed at a stable position. Therefore, even if the same eye E is measured, if the pupil P is large, the measurement position varies for each measurement, and it may be difficult to obtain a stable measurement value.
[0033]
In the measurement after the completion of the alignment, the light beam emitted from the measurement light source 17 is stopped down by the projection stop 16, forms a primary image before the objective lens 12 by the projection lens 15, and passes through the objective lens 12 and the dichroic mirror 11. And enters the center of the pupil of the eye E to be examined, and forms an image at the fundus Er. The light reflected by the fundus Er passes through the periphery of the pupil, enters the objective lens 12 again, becomes a thick light flux, and is totally reflected by the perforated mirror 13. The luminous flux reflected by the perforated mirror 13 is divided into six by a six-segment stop 18 and refracted by a six-segment prism 19 so as to be received in an appropriate range of the light receiving surface area of the two-dimensional image pickup device 21. Is projected on the two-dimensional image sensor 21.
[0034]
A video signal of a fundus image captured by the two-dimensional image sensor 21 is converted into digital data by an A / D converter 52 via a video switch 51 and stored in an image memory 53. The CPU 41 calculates the eye refractive power based on the position of the spot image of the image stored in the image memory 53.
[0035]
Originally, the refractive power is measured at the center of the pupil. Is rarely done. In addition, there is a possibility that an error between the measurement value at the center of the cornea and the measurement value at the center of the pupil may occur. However, since the eyelid covers the pupil region, the measurement position on the pupil changes and the measurement value is not stable. Can be solved.
[0036]
【The invention's effect】
As described above, the ophthalmologic apparatus according to the present invention can stably perform the alignment even when the eyelid covers the pupil region when the pupil of the subject's eye is large, and can perform the measurement quickly.
[Brief description of the drawings]
FIG. 1 is an external view of an eye refraction measuring apparatus.
FIG. 2 is an optical configuration diagram of an optometry unit.
FIG. 3 is a perspective view of a six-segment stop and a six-segment prism.
FIG. 4 is a perspective view of an alignment prism stop.
FIG. 5 is a block circuit configuration diagram.
FIG. 6 is an explanatory diagram of an anterior segment image corresponding to an alignment state.
FIG. 7 is a flowchart of automatic alignment.
FIG. 8 is an explanatory diagram for obtaining a pupil diameter.
FIG. 9 is an explanatory diagram of an anterior eye image in a state where an eyelid is lowered.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 base 2 optometry unit 3 display unit 7 printer 17 measurement light source 21, 26 two-dimensional image sensor 24 alignment prism stop 30 fixation imaging light source 31 external eye illumination light source 41 CPU
53 Image memory

Claims (1)

In an ophthalmologic apparatus that projects a light beam into a pupil of an eye to be examined and performs measurement or inspection using the reflected light, an alignment light projecting unit that projects an alignment light beam onto a cornea of the eye to be inspected, and a cornea of the alignment light beam Detecting means for detecting the reflected light flux and detecting the position of the corneal vertex; imaging means for photographing the anterior segment of the eye to be inspected; and a center position and a pupil diameter of the pupil of the eye to be inspected based on an output signal from the imaging means. Calculating means for calculating, and when the pupil diameter of the subject's eye calculated by the calculating means is larger than a predetermined value, detecting the positional deviation between the corneal apex position detected by the detecting means and the position of the optometry part and detecting the proper position When the pupil diameter of the subject's eye calculated by the calculating means is smaller than a predetermined value, the position of the pupil center of the subject's eye calculated by the calculating means is displaced from the optometric part. Detect To, ophthalmic apparatus characterized by a control means for aligning the ophthalmic examination unit in the proper position.

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