JP4136689B2 - Ophthalmic apparatus and control method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ophthalmologic apparatus that automatically aligns an eye to be examined and an optometric unit, and a control method thereof .
[0002]
[Prior art]
In a conventional eye refractive power measurement device that projects a measurement light beam on the pupil of the eye to be examined and inspects with the reflected light from the fundus, when aligning with the eye to be examined, when aligning with the corneal apex, Depending on the eye to be examined, the apex of the cornea and the center of the pupil may be decentered. If the decentering amount is large, the measurement light beam may be shifted to the iris and measurement failure may occur. For example, in the apparatus described in Japanese Patent Laid-Open No. 11-19040, measurement is performed with alignment aligned at a position as close to the corneal apex as possible so that the measurement light beam is not scattered by the iris edge.
[0003]
[Problems to be solved by the invention]
However, in the above-described conventional example, from the completion of the alignment to the completion of the measurement, it takes time for the cloud to remove the adjustment force of the eye to be examined, and the eye diameter moves during that time. Even if the measurement light beam is not focused on the iris when the alignment is completed due to a change or the like, there is a problem that the measurement light beam is applied to the iris during actual measurement, resulting in a measurement failure.
[0004]
An object of the present invention is to provide an ophthalmologic apparatus and a control method therefor that can solve the above-described problems and perform measurement by accurately and quickly aligning the eye to be examined.
[0005]
[Means for Solving the Problems]
To achieve the above object, an ophthalmologic apparatus according to the present invention includes a pupil radius calculation unit that calculates a pupil radius from an area of a pupil obtained from an anterior ocular segment image captured by an imaging unit;
Pupil center position calculating means for calculating the pupil center position from the anterior segment image imaged by the imaging means;
Judgment means for judging whether or not the difference between the pupil radius calculated by the pupil radius calculation means and the eccentric amount at the corneal apex and the pupil center position obtained from the imaging means is equal to or less than a predetermined value. When,
When the determination means determines that the difference between the pupil radius and the eccentricity is equal to or less than a predetermined value, the alignment of the optometry unit that performs the optometry of the eye to be examined is controlled based on the pupil center position. And a control unit that controls the alignment of the optometry unit based on the corneal apex position when the determination unit determines that the difference between the pupil radius and the eccentricity is greater than or equal to a predetermined value. It is characterized by having.
The ophthalmologic apparatus control method according to the present invention includes a pupil radius calculation step of calculating a pupil radius from an area of a pupil obtained from an anterior segment image captured by an imaging unit, and an anterior eye imaged by the imaging unit. The pupil center position calculating step for calculating the center position of the pupil from the partial image, the pupil radius calculated in the pupil radius calculating step, and the difference between the corneal apex obtained from the imaging means and the eccentric amount at the pupil center position When the difference between the pupil radius and the amount of eccentricity is determined to be equal to or less than a predetermined value in the determination step of determining whether or not is equal to or less than a predetermined value, Based on the pupil center position calculated in the pupil center position calculation step, the positioning of the optometry unit that performs the optometry of the eye to be examined is controlled, and in the determination step, the pupil radius and the eccentricity amount There when it is determined to be equal to or less than a predetermined value, characterized in that a control step of controlling the alignment of the ophthalmic examination unit based on a corneal vertex obtained from the imaging means.
[0006]
DETAILED DESCRIPTION OF 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. An optometry unit 2 is movably mounted on an upper part of a base 1, and a measurement value, an eye image to be examined, and the like are displayed on the operation surface of the base 1. A display unit 3 comprising a liquid crystal monitor, a CRT monitor, etc. for selecting display and settings of various devices, a trackball 4 for operating the display screen, and roughly aligning the optometry unit 2 with the eye to be examined, and a roller 5 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 the measurement result are arranged. The subject can place a face on a face receiving portion (not shown) on the opposite side of the operation surface of the base 1 and place the eye in front of the objective portion of the optometry unit 2 to perform measurement.
[0007]
FIG. 2 shows an optical configuration diagram of the inside of the optometry unit 2, and visible light is totally reflected from the eye E side on the optical axis O of the optometry unit 2 aligned with the visual axis of the eye E to be examined. A dichroic mirror 11 that partially reflects a light beam having a wavelength of 880 nm, an objective lens 12, a perforated mirror 13, a diaphragm 14, a projection lens 15, a projection diaphragm 16, and a measurement light source 17 that emits a light beam of 880 nm are sequentially arranged. . In the reflection direction of the perforated mirror 13, a six-divided diaphragm 18, a six-divided prism 19, a light receiving lens 20, and a two-dimensional image sensor 21 are sequentially arranged. The six-divided diaphragm 18 and the six-divided prism 19 have the shape shown in FIG. 3, and actually the six-divided diaphragm 18 and the six-divided prism 19 are in close contact with each other.
[0008]
On the other hand, in the reflection direction of the dichroic mirror 11, a fixation target projection optical system and a light receiving optical system that shares anterior ocular segment observation and alignment detection are arranged. As the light receiving optical system, a lens 22, a dichroic mirror 23, an alignment prism diaphragm 24, an imaging lens 25, and a two-dimensional image sensor 26 are sequentially arranged. The alignment prism diaphragm 24 has a shape as shown in FIG. 4, and three openings are provided in a row on a disk-shaped diaphragm plate. The dichroic mirror 23 side of the openings on both sides has a wavelength of only around 880 nm. Alignment prisms 24a and 27b that transmit light beams are bonded.
[0009]
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 31 a and 31 b are provided on both sides of the optical axis O in front of the eye E.
[0010]
FIG. 5 shows a block circuit configuration diagram of the eye refraction measuring apparatus. A track ball 4, a roller 5, a switch panel 6, and a printer 7 are connected to a CPU 41 that performs control, calculation, and the like. Further, a vertical drive motor 42, a front / rear drive motor 43, and a left / right drive motor 44 for driving the optometry unit 2 are connected to the CPU 41 via motor drivers 45, 46, 47, respectively. Further, a fixation target light source 30, an external illumination light source 31, and a 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. The motor driver 50 is connected.
[0011]
The outputs of the two-dimensional imaging devices 21 and 26 are connected to a video switch 51, and the outputs of the video switch 51 are divided into two, one connected to the CPU 41 and the other 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.
[0012]
In the thus configured eye refraction measuring apparatus, the operator first places the subject's face on the face cradle, and then tracks the optometry unit 2 with the optical axis O with respect to the eye E to be examined. The ball 4 and the roller 5 are operated. The operation of the trackball 4 can be performed by moving the optometry unit 2 in the left-right and front-back directions with respect to the eye E, and the roller 5 moving the optometry unit 2 in the up-down direction.
[0013]
In this operation, on the apparatus side, the CPU 41 receives output signals from the respective pulse counters and rotary encoders built in the trackball 4 and the roller 5, and the operation amount and speed can be detected. Further, the vertical drive motor 42, the front / rear drive motor 43, and the left / right drive motor 44 are driven via the motor drivers 45, 46, 47 based on the operation amount and speed.
[0014]
At the time of fixation guidance, the projection light beam of the fixed fixation projection light source 30 illuminates the fixation chart 29 from the back side, and is projected onto 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 direction of the optical axis by the rotation of the fixation guide lens motor 49 so that the diopter of the eye E can be changed.
[0015]
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 to be examined, and the cornea 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 diaphragm 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 three bright spots are imaged on the two-dimensional image sensor 26 via the imaging lens 25.
[0016]
In addition, the anterior segment image of the eye E and the corneal reflection images of the external illumination light sources 31a and 31b having a wavelength of 880 nm are also reflected by the dichroic mirror 11, passed through the lens 22, and further reflected by the dichroic mirror 23 to the alignment optical system. The light is guided and passes only through the central opening of the alignment prism diaphragm 24, and forms an image on the two-dimensional image sensor 26 through the imaging lens 25.
[0017]
The video signal of the anterior segment image captured by the two-dimensional image sensor 26 is converted into digital data by the A / D converter 52 via the video switch 51 and stored in the image memory 53. The CPU 41 performs image processing such as alignment bright spot extraction and pupil extraction based on the image stored in the image memory 53. Further, the video signal of the anterior ocular segment image captured by the two-dimensional imaging device 26 is combined with the signal from the character generating device 54, and the anterior ocular segment image, measurement value, and the like are displayed on the display unit 3. In addition, the measured value or the like is printed on the printer 7 as necessary.
[0018]
FIG. 6 is an explanatory diagram of a screen of the display unit 3 and shows an anterior segment image of the eye E to be examined by the two-dimensional image sensor 26. The anterior segment image of the eye E and the corneal reflection images of the external illumination light sources 31 a and 31 b are formed on the left and right of the pupil image by the light flux that has passed through the central aperture of the alignment prism diaphragm 24. A cornea reflection image by the measurement light source 17 is also formed as three vertical bright spots. That is, the luminous flux that has passed through the alignment prism 24a of the alignment prism diaphragm 24 is the upper bright spot, the luminous flux that has passed through the alignment prism 24b is the lower bright spot, and the luminous flux that has passed through the central opening is the central bright spot.
[0019]
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 appropriate position. An eye part image is shown, and FIG. 6C shows an anterior eye part image in a state where the working distance between the eye E to be examined and the optometry part 2 is closer than the appropriate position. The alignment shift in the working distance direction of the alignment is calculated by the shift of the X coordinate of the upper and lower bright spots, and the alignment shift in the vertical and horizontal directions is calculated by the position of the central bright spot.
[0020]
The operator moves the optometry unit 2 by the above-described operation, and a certain position so that three bright spots by 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, automatic alignment is started by pressing a measurement start switch arranged on the switch panel 6.
[0021]
FIG. 7 is a flowchart for automatic alignment. First, in step S 1, a video signal of an anterior segment image of the eye E to be inspected imaged by the two-dimensional image sensor 26 is digitally transmitted via an A / D converter 52. The data is converted into data, loaded into the image memory 53, and the CPU 41 extracts the three bright spots of the corneal reflection image from the measurement light source 17 from the anterior segment image in the image memory 53, and detects the coordinates of each bright spot. In step S2, the area of the pupil is obtained from the anterior segment image captured in the image memory 53 in step S1, and the pupil radius is calculated assuming that the pupil is circular. Subsequently, in step S3, the center of gravity of the pupil is obtained, and the coordinates of the position of the center of the pupil are detected.
[0022]
Further, in step S4, as shown in FIG. 8, the coordinates (Xs, Ys) of the central bright spot B1 among the three bright spots detected in step S1 and the coordinates of the center of the pupil Ep detected in step S3 ( By calculating (| Xs−Xp | ² + | Ys−Yp | ² ) ^1/2 from (Xp, Yp), the central bright spot B1 and the eccentric amount ΔC of the pupil center are calculated.
[0023]
Next, the process proceeds to step S5, and the shortest distance from the corneal apex position to the pupil edge is obtained. When the pupil radius is R, and the eccentricity amount between the pupil Ep and the corneal apex is ΔC, the shortest distance d from the corneal apex position to the pupil edge is obtained by (pupil radius R−eccentric amount ΔC). That is, when the value of the shortest distance d is equal to or less than the minimum measurable pupil radius r, the measurement light beam M is outside the boundary line P between the pupil Ep and the iris as shown in FIG. Therefore, the process proceeds to step S6. If (pupil radius R−eccentricity ΔC) is equal to or greater than the minimum measurable pupil radius r, the measurement light flux is not lost by the iris, and the process proceeds to step S7.
[0024]
In this embodiment, the shortest distance d from the corneal apex position to the pupil edge is compared with the minimum measurable pupil radius r, but it is compared with a value slightly larger than the minimum measurable pupil radius r with a margin. May be.
[0025]
In step S6, the amount of misalignment in the XY direction, which is the horizontal and vertical directions with respect to the measurement optical axis of the optometry unit 2, is calculated from the coordinates of the pupil center calculated in step S3, and the process proceeds to step S8.
[0026]
In step S7, the amount of deviation in alignment in the XY direction with respect to the measurement optical axis of the optometry unit 2 is calculated from the coordinates of the central bright spot B1 among the three cornea reflection images detected in step S1, and the process proceeds to step S8. Transition.
[0027]
Subsequently, in step S8, the amount of deviation in alignment in the Z direction, which is the working distance direction, is obtained from the amount of deviation in the X coordinate of the upper and lower bright spots of the cornea reflection image detected in step S1. In step S9, it is determined whether or not the amount of deviation in each of the XYZ directions is within a predetermined range. If the amount of deviation is larger than the predetermined range, the process proceeds to step S10. The motor 43 and the left / right drive motor 44 are driven to reduce the misalignment, and the process returns to step S1.
[0028]
Steps S1 to S10 described above are repeated until it is determined in step S9 that the amount of deviation is within a predetermined range. After completing the automatic alignment operation, the measurement operation is performed to calculate the measurement value.
[0029]
In the measurement after the alignment is completed, the light beam emitted from the measurement light source 17 is focused by the projection diaphragm 16, and is primarily imaged by the projection lens 15 before the objective lens 12, and passes through the objective lens 12 and the dichroic mirror 11. Then, the light enters the center of the pupil of the eye E and forms an image on the fundus Er. The reflected light from the fundus Er passes through the periphery of the pupil and enters the objective lens 12 again, becomes a thick light beam, and is totally reflected by the perforated mirror 13. The light beam reflected by the perforated mirror 13 is divided into six by the six-divided diaphragm 18 and refracted by the six-divided 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. Are projected on the two-dimensional image sensor 21.
[0030]
The image signal of the fundus image captured by the two-dimensional image sensor 21 is converted into digital data by the A / D converter 52 via the video switch 51 and stored in the 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.
[0031]
In the present embodiment, the magnitude of the eccentricity between the corneal apex and the pupil Ep is not a problem, but the cause of the eccentricity between the corneal apex and the pupil Ep is that the pupil Ep of the eye E is really eccentric. In some cases, the line of sight of the eye E is displaced from the optical axis of the measurement light beam M, as shown in FIG. In particular, when the amount of eccentricity is large, the line of sight often deviates greatly. In such a state, accurate measurement cannot be performed. Therefore, when the amount of eccentricity ΔC is large, for example, 2 mm or more, A large amount of eccentricity of the pupil Ep is displayed on the display unit 3 as a warning. Alternatively, the operator may be notified by printing a warning mark along with the measurement value on the printer 7.
[0035]
【The invention's effect】
As described above, the ophthalmologic apparatus and the control method thereof according to the present invention determine whether the amount of eccentricity between the corneal apex position and the pupil center position is larger or smaller than a predetermined value with respect to the pupil radius. When the difference is small, the optometry part is aligned based on the pupil center position, and when the difference is large, the optometry part is aligned based on the corneal apex position, and the measurement error and the reliability are low. Since useless measurement such as measurement can be reduced, the burden on the subject can be reduced.
[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-part diaphragm and a six-part prism.
FIG. 4 is a perspective view of an alignment prism diaphragm.
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 of a pupil, a corneal apex, and a measurement light beam.
FIG. 9 is an explanatory diagram of an anterior segment image when the visual axis is deviated.
DESCRIPTION OF SYMBOLS 1 Base 2 Optometry part 3 Display part 7 Printer 17 Measurement light source 21, 26 Two-dimensional image sensor 24 Alignment prism diaphragm 30 Fixation imaging light source 31 External illumination light source 41 CPU
53 Image memory

Claims (3)

Pupil radius calculation means for calculating the pupil radius from the area of the pupil obtained from the anterior segment image imaged by the imaging means;
Pupil center position calculating means for calculating the pupil center position from the anterior segment image imaged by the imaging means;
Judgment means for judging whether or not the difference between the pupil radius calculated by the pupil radius calculation means and the eccentric amount at the corneal apex and the pupil center position obtained from the imaging means is equal to or less than a predetermined value. When,
When the determination means determines that the difference between the pupil radius and the eccentricity is equal to or less than a predetermined value, the alignment of the optometry unit that performs the optometry of the eye to be examined is controlled based on the pupil center position. And control means for controlling the alignment of the optometry unit based on the corneal apex position when the determination means determines that the difference between the pupil radius and the eccentricity is equal to or greater than a predetermined value. An ophthalmologic apparatus characterized by comprising: The ophthalmologic apparatus according to claim 1, wherein the predetermined value is a minimum measurable pupil radius or a measurable minimum pupil radius by the optometry unit. A pupil radius calculation step of calculating a pupil radius from the area of the pupil obtained from the anterior segment image imaged by the imaging means;
A pupil center position calculating step of calculating the center position of the pupil from the anterior segment image imaged by the imaging means;
Determination step of determining whether or not the difference between the pupil radius calculated in the pupil radius calculation step and the eccentricity amount at the corneal apex and the pupil center position obtained from the imaging means is equal to or less than a predetermined value. When,
When it is determined in the determining step that the difference between the pupil radius and the eccentricity is equal to or less than a predetermined value, the eye of the eye to be examined is based on the pupil center position calculated in the pupil center position calculating step. Obtained from the imaging means when controlling the alignment of the optometry part that performs optometry and determining in the determination step that the difference between the pupil radius and the eccentricity is less than or equal to a predetermined value And a control step of controlling the alignment of the optometry unit based on a corneal apex.

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