Source: https://patents.google.com/patent/EP1767144B1/en
Timestamp: 2020-04-04 10:25:14
Document Index: 80086350

Matched Legal Cases: ['art 4', 'art 4', 'art 6', 'art 70', 'art 70', 'art 70', 'art 6', 'art 80', 'art 80', 'art 70', 'art 70', 'art 4', 'art 70', 'art 4', 'art 70', 'art 4', 'art 70', 'art 6', 'art 4', 'art 4', 'art 4', 'art 70', 'art 70', 'art 4', 'art 80']

EP1767144B1 - Eye refractive power measurement apparatus - Google Patents
EP1767144B1
EP1767144B1 EP06020177A EP06020177A EP1767144B1 EP 1767144 B1 EP1767144 B1 EP 1767144B1 EP 06020177 A EP06020177 A EP 06020177A EP 06020177 A EP06020177 A EP 06020177A EP 1767144 B1 EP1767144 B1 EP 1767144B1
EP06020177A
EP1767144A1 (en
2006-09-26 Application filed by Nidek Co Ltd filed Critical Nidek Co Ltd
2007-03-28 Publication of EP1767144A1 publication Critical patent/EP1767144A1/en
2012-06-06 Publication of EP1767144B1 publication Critical patent/EP1767144B1/en
Conventionally, there is an eye refractive power measurement apparatus which projects a measurement target onto a fundus of an examinee's eye to pick up a fundus reflection image by a two-dimensional image-pickup element, stores the picked-up (detected) fundus reflection image as a measurement image, and obtains eye refractive power of the eye based on the stored measurement image. Proposed as this kind of apparatus is one which is capable of displaying the measurement image by operation of a display changeover switch in order to check reliability of a measurement result (see Japanese Patent Application Unexamined Publication No. Hei1-129830 ).
However, it takes time and trouble to display the measurement image by operation of the display changeover switch, and even if the measurement image is displayed, it is sometimes difficult for an unaccustomed examiner to check reliability of the measurement result.
Document US 5 751 396 describes an ophthalmic measuring apparatus particularly for observation by retroillumination. The ophthalmic measuring apparatus is provided with an eye measuring system, an observing system enabling observation of the eye to be examined by the examiner, an anterior segment illuminating system and a control system. The ophthalmic apparatus is provided with an observing system enabling observation of the eye to be examined, an ocular fundus illuminating system, a time measuring means and a control system.
Document EP 0 928 596 describes a subjective eye refractive power measuring apparatus measuring the refractive power of an optical system to be tested. The subject eye refractive power measuring apparatus comprises a measuring element that outputs a detection signal corresponding to the refractive power of the optical system to be tested, an arithmetic device that calculates a measured value related to the refractive power based upon an output signal from the measuring element, a determination device that determines whether or not specific conditions related to termination of a measuring operation are satisfied and a termination device that implements specific control for terminating a measuring operation when the judgement device has determined that specific conditions are satisfied. The conditions for terminating measuring operation are based upon, at least, either a measured value obtained by the arithmetic device or the length of measurement time required for measurement.
Document US 4 812 033 describes an ophthalmic apparatus having an objective optical system opposed to an eye to be examined. First and second photodetectors are provided on the substantially conjugate plane of the iris of the eye to be examined with respect to the objective optical system when the operating distance to the eye to be examined is appropriate. The photodetectors detect the image of the iris of the eye to be examined and the image of the pupil of the eye to be examined, respectively, and a detecting device compares the output of the first and second photodetectors and detects the state of alignment with the eye to be examined.
Document EP 1 402 810 describes a noncontact tonometer that stores, into a storage unit, the image of an anterior ocular segment immediately before an intraocular pressure value is measured, and that, if an anomaly is found in the measurement result, facilitates the specification of the reason of the anomaly by automatically displaying the image of the anterior ocular segment that was acquired in advance.
An obj ect of the invention is to overcome the problems described above and to provide an eye refractive power measurement apparatus by which an examiner can properly check reliability of a measurement result while time and effort of the examiner are saved.
The object is solved by the features of independent claims. The dependent claims are directed to preferred embodiments of the invention.
A detailed description of one preferred embodiment of an eye refractive power measurement apparatus embodied by the present invention is provided below with reference to the accompanying drawings. Fig. 1 is a schematic external view of the eye refractive power measurement apparatus consistent with one preferred embodiment of the present invention. The measurement apparatus includes a base 1, a face (head) supporting unit 2 attached to the base 1, a mobile base 3 provided movably on the base 1, and a measurement part (measurement unit) 4 provided movably on the mobile base 3 and housing a measurement optical system and the like. By tilting operation of a joystick 5, the mobile base 3 is moved in a right-and-left direction (hereinafter, an X-direction) and a back-and-forth direction (a working distance direction: hereinafter, a Z-direction). In addition, by rotating operation of a rotation knob 5a, the measurement part 4 is moved on the mobile base 3 in an up-and-down direction (hereinafter, a Y-direction). In addition, the measurement part 4 is moved in the X,Y,Z-directions with respect to an eye E of an examinee by an XYZ movement part 6 provided to the mobile base 3. At the tip of the joystick 5, a measurement starting switch 5b is provided. In addition, a monitor 7 is provided on the mobile base 3.
Fig. 2 is a view showing a schematic configuration of an optical system and a control system of the measurement apparatus. A measurement optical system 10 includes a projection optical system 10a for projecting a measurement target (measurement light) in a spot shape onto a fundus Ef via a central pupillary portion of the eye E, and a photo-receiving optical system 10b for picking up fundus reflection light in a ring shape via a peripheral pupillary portion of the eye E and picking up a fundus reflection image in a ring shape by a two-dimensional image-pickup element.
The projection optical system 10a includes an infrared light source 11 for measurement, a relay lens 12, a hole mirror 13 and an objective lens 14 for measurement, which are placed on an optical axis L1 of the measurement optical system 10. The light source 11 is placed in a position optically conjugate with the fundus Ef of the eye E with emmetropia. In addition, an opening of the hole mirror 13 is placed in a position optically conjugate with a pupil of the eye E.
The photo-receiving optical system 10b shares the obj ective lens 14 and the hole mirror 13 with the projection optical system 10a, and includes a relay lens 16 and a total reflection mirror 17 which are placed on the optical axis L1 in a reflecting direction of the hole mirror 13, and a photo-receiving diaphragm 18, a collimator lens 19, a ring lens 20 and a two-dimensional image-pickup element 22 such as an area CCD which are placed on the optical axis L1 in a reflecting direction of the total reflection mirror 17. The photo-receiving diaphragm 18 and the image-pickup element 22 are placed in positions optically conjugate with the fundus Ef. As shown in Figs. 3A and 3B, the ring lens 20 is constituted of a lens portion 20a which is a cylindrical lens formed in a ring shape on one side of a transparent plate, and a light shielding portion 20b formed of coating for light shielding which is provided to the portions other than the ring-shaped cylindrical lens forming the lens portion 20a, and is placed in a position optically conjugate with the pupil. Output from the image-pickup element 22 is inputted to a calculation and control part 70 via an image memory 71.
An observation optical system 50 shares the obj ective lens 36 and the dichroic mirror 35.with the fixation target projection optical system 30, and includes an image-pickup lens 51 and a two-dimensional image-pickup element 52 which are placed on the optical axis L2 in a reflecting direction of the dichroic mirror 35. Output from the image-pickup element 52 is inputted to the calculation and control part 70. Accordingly, an image of the anterior segment of the eye E is picked up by the image-pickup element 52 to be displayed on the monitor 7. Incidentally, the observation optical system 50 doubles as a target image detection optical system for detecting an image of the ring target and images of the infinite targets.
The calculation and control part 70 is connected with the image-pickup element 52, the image memory 71, a memory 75, the knob 5a, the switch 5b, the XYZ movement part 6, the monitor 7, a switch part 80 having a plurality of switches and used for various settings, and the like. Placed on the switch part 80 are an alignment mode changeover switch 80a for making a changeover between an automatic alignment mode and a manual alignment mode, a measurement mode changeover switch 80b for making a changeover between an automatic measurement mode in which a trigger signal for starting measurement is automatically generated upon completion of alignment and a manual measurement mode in which a trigger signal for starting measurement is generated by operation of the switch 5b, and the like. The calculation and control part 70 controls the entire apparatus, and performs calculation of eye refractive power, calculation of a corneal shape and the like.
In the case of the automatic alignment mode, the calculation and control part 70 detects an alignment state of the measurement part 4 with respect to the eye E based on the output from the image-pickup element 52. In this case, based on the central position of the detected ring target image, the calculation and control part 70 obtains the alignment state in the X,Y-directions of the measurement part 4 with respect to the eye E. In addition, based on a distance between the detected infinite target images and a space in a predetermined meridional direction of the ring target image, the calculation and control part 70 calculates the alignment state in the Z-direction of the measurement part 4 with respect to the eye E (for details, see USP 5,463,430 corresponding to Japanese Patent Application Unexamined Publication No. Hei6-46999 ). Then, the calculation and control part 70 drives and controls the XYZ movement part 6 based on detection results on the alignment states to automatically perform alignment of the measurement part 4 with respect to the eye E.
In addition, in the case of the manual alignment mode, the examiner operates the joystick 5 while observing the ring target image R displayed on the monitor 7, and adjusts a position of the measurement part 4 in the X, Y-directions so that the ring target image R and a reticle mark 101 become concentric circles. In addition, the examiner adjusts a position of the measurement part 4 in the Z-direction with reference to an indicator 103 (or so that the ring target image R becomes thinnest).
In the case of the automatic measurement mode, measurement is automatically started upon completion of the alignment. On the other hand, in the case of the manual measurement mode, measurement is started when the alignment is completed and the examiner operates the switch 5b.
The calculation and control part 70 controls to light the light source 11 based on input of the trigger signal for starting measurement. The measurement light emitted from the light source 11 is projected onto the fundus Ef via the relay lens 12 to the half mirror 29 and forms a point light source image in a spot shape on the fundus Ef.
First, described is the judgment as to whether or not the measurement image satisfies the predetermined measurement condition. Fig 7A to 7D are views showing examples of the measurement image for which it is considered proper to be judged as measurement image error in this judgment. Fig. 7A is a view showing a state of the ring image of which an upper side is missing because of a blink of the eye E during measurement. Fig. 7B is a view showing a state of the ring image in which an abnormal reflection image unintentionally appears in the peripheral part because of scatter of light caused by opacity of an optic media portion (a crystalline lens and the like) of the eye E. Fig. 7C is a view showing a state of the ring image of which an upper side is missing because the eye E has a small pupil. Fig. 7D is a view showing a state of the ring image in which irregular distortion is unintentionally generated because the eye E has irregular astigmatism. In any of these cases, detection of the position of the ring image and the like cannot be performed with high accuracy. Incidentally, the ring image shown in Fig. 5 is an example of a normal measurement image.
Next, the judgment as to whether or not the alignment state is appropriate is described. The judgment as to whether or not the alignment state during measurement is appropriate is made because there are not a few cases where the alignment is deviated by movement of the eye E during measurement (during obtainment of the measurement image). If the alignment deviation occurs during measurement, reliability of the measurement result is lowered.
Incidentally, when the monitor 7 is controlled to display the measurement image, a message specifically saying the cause of the measurement image error may be displayed. To be more specific, the calculation and control part 70 automatically specifies the cause of the measurement image error based on the measurement image stored in the image memory 71, and controls to display a message saying the specified cause of the measurement image error (such as letters and graphics) along with the measurement image. For example, two ring images pickup up at different times are previously stored in the memory 71 to be compared, and in a case where one of them does not have a missing part and the other one has a missing part, or the like, a message saying the occurrence of blink (for example, "BLINK") is displayed. In a case where the peak values of the brightness signals of the ring image, the width in the predetermined meridian direction of the ring image and the like exceed the predetermined threshold values, a case where the ring image has a plurality of missing parts, or the like, a message saying the presence of opacity (for example, "CATARACT") is displayed. In a case where the ring image has a missing part even though the alignment state is appropriate, or the like, a message saying an eye with a small pupil (for example, "SMALL PUPIL") is displayed. In a case where the difference between the shape of the ellipse obtained when the ring image is subjected to ellipse fitting and the shape of the actual ring image is great, or the like, a message saying an eye with irregular astigmatism (for example, "IRREGULAR") is displayed. In a case where the measurement image has characteristics unique to an eye in which an intraocular lens is implanted, a message saying an eye in which an intraocular lens is implanted (for example, "IOL") is displayed. Incidentally, if there are a plurality of causes of the measurement image error, a plurality of messages may be displayed, or a message saying a more likely cause of the measurement image error or a message saying a cause with greater influence on the measurement image error may be displayed. By such operation, the examiner can check the cause of the measurement image error visually.
Next, described will be the display control of the monitor 7 based on the measurement error when there are an ordinarily-used first measurement mode for making a judgment as to whether or not the measurement image satisfies a predetermined first measurement condition and a second measurement mode for making a judgment as to whether or not the measurement image satisfies a predetermined second measurement mode which is more relieved than the first measurement condition, referring to the flowchart in the case of the automatic measurement mode (see Fig. 9). As for the second measurement mode, for example, when utilizing the degree of the missing part of the ring image as the measurement condition, whether or not more than three quarters of the ring image is missing is regarded as the second measurement condition, while whether or not more than half of the ring image is missing is regarded as the first measurement condition in the first measurement mode. Incidentally, in the second measurement mode, the eye E which causes the measurement error in the first measurement mode is intended to measure; accordingly, the light quantity of the light source 11 may be increased, or gain of the image-pickup element 22 may be increased.
Incidentally, after the completion of the measurement on both the eyes, and when a changeover of the eye to be measured is made by moving the measurement part 4, a changeover between the measurement image of the right eye and the measurement image of the left eye may be made to display on the monitor 7. In other words, based on a signal from a measured-eye detection part (a signal of the changeover of the eye to be measured), the changeover of the measurement image to display is made. In addition, the measurement image of the right eye and the measurement image of the left eye may be displayed together on the monitor 7.
In addition, it is also available to provide a first display mode for displaying the measurement image on the monitor 7 when judged as the measurement error as mentioned above, and a second display mode for displaying the measurement image on the monitor 7 irrespective of the judgment result on the measurement error, so that a display mode of the measurement image can be selected based on a selection signal from a mode selecting switch for selecting which mode to use, which is in the switch part 80. Owing to such configuration, selecting the second display mode allows the examiner to check the measurement image when the measurement error does not arise; accordingly, the examiner can check that there are no causes that may produce measurement error, based on the measurement image, In addition, the measurement image when the measurement error arises and the measurement image when the measurement error does not arise can be visually compared. In this case, if the examiner becomes accustomed to specifying the cause of the measurement error from the measurement image in the second display mode, it also becomes possible to employ the first display mode.
An eye refractive power measurement apparatus for measuring eye refractive power of an examinee's eye (E), the apparatus comprising:
a measurement optical system (10) for protecting a measurement target onto a fundus (Ef) of the eye said system including a two-dimensional image-pickup element (22) to pick up a fundus reflection image of the measurement target;
storing means (71) for storing the picked-up fundus reflection image of the measurement target as a measurement image;
a calculation and control part (70) for calculating a measurement value of the eye refractive power based on the stored measurement image; said calculation and control part being adapted to make a judgment as to whether or not the stored measurement image satisfies a predetermined first measurement condition and
a monitor (7) for displaying the calculated measurement value;
characterized in that said calculation and control part to control the monitor to display the stored measurement image irrespective of a result of the judgment.
The eye refractive power measurement apparatus according to claim 1,
wherein the calculation and control part is adapted to make a judgment as to whether or not an alignment state of the measurement optical system with respect to the eye during measurement is appropriate and to control the monitor to display a message saying "alignment error" when it is judged that the alignment state during measurement is not appropriate.
The eye refractive power measurement apparatus according to any one of claims 1 to 2, wherein said measurement image is a ring image wherein the calculation and control part is adapted to make a judgment as to whether or not the stored measurement image satisfies a predetermined first measurement condition, and when it is judged that the stored measurement image does not satisfy the first measurement condition said first measurement condition being whether or not more than half of a ring image is missing, to make a judgment as to whether or not the stored measurement image satisfies a predetermined second measurement condition which is whether or not more than three quarters of a ring image is missing.
The eye refractive power measurement apparatus according to any one of claims 1 to 3, wherein the calculation and control part is adapted to specify, when it is judged that the stored measurement image does not satisfy the measurement condition, a cause thereof, and to control the monitor to display the specified cause.
The eye refractive power measurement apparatus according to any one of claims 1 to 4, wherein the calculation and control part is adapted to control the monitor to display the measurement value when it is judged that the stored measurement image satisfies the measurement condition, and controls the monitor to display a message saying measurement image error when it is judged that the stored measurement image does not satisfy the measurement condition.
The eye refractive power measurement apparatus according to any one of claims 1 to 5, wherein the calculation and control part is adapted to calculate a reliability coefficient indicating the degree of reliability of the measurement value in stages based on the stored measurement image, and to control the monitor to display the measurement value while assigning the reliability coefficient to the measurement value.
EP06020177A 2005-09-27 2006-09-26 Eye refractive power measurement apparatus Active EP1767144B1 (en)
JP2005280971A JP5085858B2 (en) 2005-09-27 2005-09-27 Eye refractive power measuring device
EP1767144A1 EP1767144A1 (en) 2007-03-28
EP1767144B1 true EP1767144B1 (en) 2012-06-06
EP06020177A Active EP1767144B1 (en) 2005-09-27 2006-09-26 Eye refractive power measurement apparatus
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