JP2006314591A - Ocular optical characteristic measuring apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To set an optimum measurement range and to select an optimum image for measurement without interposing the individual difference of an examiner in the case of setting a measurement range for acquiring light receiving images and selecting an image suitable for the measurement from the plurality of acquired images in the case of measuring ocular optical characteristics from the light intensity distribution of the light receiving images for which a visual target image from the eye fundus of an eye to be examined is light-received. <P>SOLUTION: This ocular optical characteristic measuring apparatus comprises: a visual target projection optical system 2 for projecting the visual target image to the eye fundus of the eye to be examined; a light receiving means 21 for light-receiving the visual target image from the visual target image projection system reflected from the eye fundus of the eye to be examined; and a control part 28 capable of acquiring the plurality of visual target images light-received by the light receiving means corresponding to diopters, deciding the shapes of the plurality of acquired images and correlating the shapes with the diopters. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an eye optical characteristic measuring apparatus capable of calculating an eye optical characteristic of a subject's eye based on a light intensity distribution characteristic of a target image projected on the fundus of the subject's eye.

  Conventionally, it has a target projection means for projecting a target image on the fundus of the eye to be examined and a light receiving means for guiding the target image onto a photoelectric detector, and the target detected by the photoelectric detector 2. Description of the Related Art An eye optical property measuring apparatus that obtains an eye optical property of an eye to be examined by calculation based on a light intensity distribution of an image is known.

  Further, as shown in Patent Document 1, the present applicant computes and displays a simulation image on the fundus that will be formed when a target image is projected onto the fundus of the eye to be examined from the obtained eye optical characteristics, An eye optical characteristic measuring apparatus has been proposed that can objectively observe what kind of image is formed on the fundus of the subject's eye and how the subject is viewing.

  In the eye optical characteristic measuring apparatus, a plurality of light intensity distribution images to be measured are acquired, and eye optical characteristics are obtained from one of the images.

  In the above-described measurement of the optical characteristics of the eye, it is necessary to know in detail the diopter value of the measurement position of the image used for the calculation as compared with the power of the eye to be measured measured with a refractometer or the like. For this reason, rough measurement is performed with the coarse diopter position movement amount in the measurement range including the measurement target position, and then the measurement range and diopter position movement amount are set again to obtain detailed diopter positions for calculating the optical characteristics of the eye. This measurement is performed to obtain images in

  At this time, after measuring with the amount of movement of the rough diopter position, setting of the measurement range and the like for performing the main measurement must be judged by the examiner himself comparing a plurality of images, which is very troublesome and time consuming. There was a problem of hanging. Furthermore, since setting of the measurement range, etc. is left to the subjective judgment of the examiner, images of the same condition are not necessarily selected even by the same examiner, even though they are the same eye to be examined. There was a possibility of different measurement results.

  In addition, regarding the measurement range of the above-described ocular optical characteristics, in the plurality of acquired images, in addition to the image having the minimum circle of confusion used for calculation, an image of the front and rear focal lines is included. It is very useful for diagnosis of the eye to be examined. For this reason, it is necessary for the examiner to set the measurement range so that the front and rear focal line images are included, but since the setting is also made based on the subjective judgment of the examiner, at the time of actual measurement, There was a problem that the front and rear focal line images could not be acquired within the measurement range, and it was necessary to set the measurement range again and perform measurement again, increasing the burden on the subject.

  Furthermore, when the diopter value of the eye to be examined is unknown in advance, the examiner makes a subjective judgment and determines the measurement range even for the target position at the initial stage of measurement, and thus the above-mentioned problem occurs more frequently.

JP 2003-70741 A

JP 2002-209852 A

  In view of such a situation, the present invention sets a measurement range for acquiring a received light image when measuring eye optical characteristics from a light intensity distribution of a received light image that has received a target image from the fundus of the subject's eye. When an image suitable for measurement is selected from these images, an optimum measurement range can be set and an optimum measurement image can be selected without any individual differences between examiners.

  The present invention provides a target projection optical system for projecting a target image on the fundus of the subject's eye, a light receiving means for receiving a target image from the target image projection system reflected from the fundus of the subject's eye, and the light reception A plurality of optotype images received by the means can be acquired in correspondence with the diopter, and an ophthalmic optical characteristic comprising a control unit that determines the shape of the acquired images and associates the shape with the diopter. The control unit relates to an ophthalmic optical characteristic measurement device configured to set a measurement range based on a plurality of acquired image shapes, and the control unit includes a plurality of acquired images. , By determining and selecting the minimum circle of confusion from the judgment of the image shape, and relating to an eye optical characteristic measuring apparatus configured to set the minimum circle of confusion as a reference of the measurement range, and also, by the control unit, image of the minimum circle of confusion Ophthalmic optical characteristics with the measurement range as the center The control unit relates to an ophthalmic optical characteristic measuring apparatus capable of selecting an image that can be identified as a minimum circle of confusion, a front focal line, and a rear focal line from the shape determination of a plurality of acquired images. The present invention relates to an ophthalmic optical characteristic measuring apparatus in which an image is acquired at a predetermined diopter pitch in a set measurement range, and an image of a minimum circle of confusion is selected from the acquired image by shape determination, and the control unit is selected The present invention relates to an eye optical characteristic measurement device that calculates light intensity distributions in a plurality of meridian directions of a minimum confusion circle image and calculates the eye optical characteristics of the eye to be examined based on the light intensity distribution, and the control unit has a set measurement range In addition, the present invention relates to an ophthalmic optical characteristic measurement apparatus that can set a diopter pitch according to the above, and further includes an operation unit that can set measurement conditions, and sets a measurement range centering on the image of the minimum circle of confusion through the operation unit. Possible ophthalmic optics Those relating to sexual measuring device.

  According to the present invention, a target projection optical system for projecting a target image on the fundus of the subject's eye, and a light receiving means for receiving the target image from the target image projection system reflected from the fundus of the subject's eye, Since a plurality of target images received by the light receiving means can be acquired in correspondence with the diopter, and the control unit is configured to determine the shapes of the acquired images and to associate the shapes with the diopters. Then, the shape of the target image reflected from the fundus of the eye to be examined and the diopter of the eye to be examined are objectively associated, and the setting of the measurement range and the information on the eye refractive power of the eye to be examined can be easily obtained based on the image.

  Further, according to the present invention, the control unit can select an image that can be recognized as the minimum circle of confusion, the front focal line, and the rear focal line from the obtained shape determination of the plurality of images, and the eye refractive power measurement can be performed by the examiner. Measurement is possible without individual differences.

  According to the invention, the control unit obtains light intensity distributions in a plurality of meridian directions of the selected minimum confusion circle image, and calculates the optical optical characteristics of the eye to be examined based on the light intensity distributions. It is possible to select an appropriate minimum circle of confusion without depending on the subjectivity of the tester, and the same measurement result can be obtained even if the examiner is different, improving the reliability and reducing the workload of the examiner. Excellent effects such as improved shortening operability are exhibited.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  First, referring to FIG. 1, an optical system of an eye optical characteristic measuring apparatus in which the present invention is implemented will be described.

  In the figure, 1 is an eye to be examined, 2 is a projection optical system for projecting a point-like target image on the eye to be examined, and 3 is a light receiving optical system for guiding a target image obtained by reflection from the fundus of the eye to be examined to a light receiver. Reference numeral 4 denotes a light source unit including a light source 5 and a relay lens 6.

  The projection optical system 2 is transmitted through a light source 5, a relay lens 6 that condenses the projection light beam emitted from the light source 5, a half mirror 7 disposed on the optical axis of the relay lens 6, and the half mirror 7. A polarizing beam splitter 8 for projecting a projected light beam toward the eye 1 to be reflected and reflecting a linearly polarized light component (S linearly polarized light) in the first polarization direction, and the polarizing beam splitter 8 side on the projection optical axis of the polarizing beam splitter 8 A relay lens 9, an objective lens 11, and a quarter-wave plate 13. A projection system aperture stop 14 is provided at a required position of the projection optical system 2, for example, between the half mirror 7 and the polarization beam splitter 8. Further, a fixation target system 17 having a fixation target 15 and a relay lens 16 is disposed opposite to the half mirror 7.

  The light source 5 and the fixation target 15 are in a conjugate position with the fundus of the eye 1 to be examined. As will be described later, the light source 5 and the fixation target 15 are imaged on the fundus through the pupil 18. The pupil 18 is in a conjugate or substantially conjugate position with the projection system aperture stop 14. The fixation target 15 is marked with a visual acuity test target, for example, a Landolt ring. Here, in the light source unit 4, the light source 5 and the relay lens 6 are integrally formed, and the light source unit 4 is movable along the optical axis direction in conjunction with a focusing lens 19 described later. The movement of the light source unit 4 and the focusing lens 19 is executed by a driving unit (not shown), and the driving unit is controlled by a control unit 28 described later.

  The light receiving optical system 3 shares the projection optical system 2 with the polarizing beam splitter 8, the relay lens 9, the objective lens 11, and the quarter wavelength plate 13 disposed on the projection optical axis of the polarizing beam splitter 8. is doing.

  A light receiving system aperture stop 22, a movable focusing lens 19, and an imaging lens 20 are disposed along the reflected optical axis on the reflected optical axis that passes through the polarizing beam splitter 8. The reflected light beam is imaged on the photoelectric detector 21. The photoelectric detector 21 and the fundus of the subject eye 1 are in a conjugate or substantially conjugate position.

  FIG. 2 shows the projection system aperture stop 14 and the light receiving system aperture stop 22. In the present embodiment, the projection system aperture stop 14 and the light receiving system aperture stop 22 are the same. . Hereinafter, the projection system aperture stop 14 will be described.

  The projection system aperture stop 14 is a disc in which a required number, for example, six aperture holes 23a, 23b, 23c, 23d, 23e, and 23f are formed, and the aperture holes 23a, 23b, 23c, 23d, and 23e are formed. , 23f are provided at six equal positions on the same circumference, and the hole diameter is about φ1 mm to φ8 mm in consideration of the size of the pupil. For example, φ1 mm, φ2 mm, φ3 mm, φ4 mm, φ5 mm, and φ6 mm are selected.

  The projection system aperture stop 14 and the light receiving system aperture stop 22 are rotatably provided, and the centers of the aperture holes 23a, 23b, 23c, 23d, 23e, and 23f are the optical axes of the projection optical system 2 and the light receiving optical system. It matches with the optical axis of 3.

  The projection system aperture stop 14 and the light receiving system aperture stop 22 are attached to, for example, a stepping motor (not shown), and the stepping motor is controlled to be intermittently rotated by the control unit 28. The required throttling holes of the throttling holes 23a, 23b, 23c, 23d, 23e, and 23f are selected by intermittently rotating at a time. Each stepping motor is independently controlled by a control unit 28 described later. Selection of the apertures 23a, 23b, 23c, 23d, 23e, and 23f is selected according to the pupil diameter of the subject, and the diameter of the aperture 23 selected by the projection system aperture stop 14 and the light receiving system aperture are selected. By changing the diameter of the aperture 23 selected by the aperture 22, for example, the diameter of the aperture 23 selected by the light receiving system aperture stop 22 is made larger than the diameter of the aperture 23 selected by the projection system aperture stop 14. When set, a PTF (Phase Transfer Function) can be calculated from an image obtained by the photoelectric detector 21.

  The photoelectric detector 21 is a CCD light receiving sensor or the like, and the light receiving surface is a set of pixels, and the light receiving signal is a set of signals from each pixel. Based on the light receiving signal, the position of each pixel in the light receiving surface, the light receiving surface The shape of the image can be detected. The position of each pixel and the shape of the image are determined by setting coordinates on the light receiving surface and calculating the coordinate value of each pixel. The received light signal from the photoelectric detector 21 is stored in the storage unit 27 via the signal processing unit 26.

  The storage unit 27 has a data storage unit (not shown) and a program storage unit (not shown), and a signal processed by the signal processing unit 26 is written into the data storage unit, and writing is performed. It is controlled by the control unit 28. As described above, the control unit 28 controls the driving mechanism and functions as an eye optical characteristic calculation unit, and includes a simulation image calculation unit (not shown) and a visual acuity calculation unit (not shown). Based on the data stored in the storage unit 27, a required calculation is performed, and the calculation result is displayed on the display unit 29.

  The storage unit 27 corresponds to a received light image determination program for determining the state of the received light image based on the signal from the photoelectric detector 21, an instruction from the examiner, or a determination result from the received light image determination program. In addition, a sequence program for performing measurement and a calculation program for calculating eye optical characteristics and a simulation image based on the received light signal from the photoelectric detector 21 are stored. Further, the controller 28 receives instructions and commands from an operator from an operation panel 30 or an operation unit 30 such as a keyboard.

  Hereinafter, the operation of the optical system will be described.

  A projection light beam is projected by the projection optical system 2 in a state where the fixation target 15 is focused on the eye 1 to be examined. Note that visible light is used for the fixation target 15, and infrared light is used for the projected light beam.

  The projected light beam (infrared light) emitted from the light source 5 is transmitted through the relay lens 6 and the half mirror 7, and the transmitted light beam has a light beam diameter determined by the aperture stop 14. Then, the S linearly polarized light component is reflected by the polarizing beam splitter 8, is projected onto the fundus of the subject eye 1 through the relay lens 9, the objective lens 11, the quarter-wave plate 13, and as a point image. A primary visual target image is formed.

  When the S linearly polarized light is transmitted through the quarter wavelength plate 13, it becomes right circularly polarized light. The projected light beam is reflected by the fundus of the eye 1 to be examined, and the reflected light beam is reflected by the fundus, thereby becoming left circularly polarized light. Further, when the reflected light beam passes through the ¼ wavelength plate 13, it becomes P linearly polarized light having a polarization direction different from that of the S linearly polarized light by 90 °.

  P linearly polarized light is guided to the polarization beam splitter 8 by the objective lens 11 and the relay lens 9. Since the polarizing beam splitter 8 reflects S linearly polarized light and transmits P linearly polarized light, the reflected light beam passes through the polarizing beam splitter 8, and the received light beam diameter is determined by the light receiving system aperture stop 22. The reflected light beam that has passed through the light receiving system aperture stop 22 is imaged as a secondary target image on the photoelectric detector 21 by the focusing lens 19 and the imaging lens 20.

  The light intensity distribution of the secondary target image received by the photoelectric detector 21 reflects the ocular optical characteristics of the eye 1 to be examined. By detecting the light receiving state of the photoelectric detector 21, the ocular optical characteristics are detected. Can be measured.

  Next, the operation for measuring the eye optical characteristics will be described with reference to FIGS.

  When a measurement start command is issued from the operation unit 30 by the examiner, a required program such as a sequence program is developed and measurement is started.

  (Step 01) First, rough measurement is performed. The light source unit 4 and the focusing lens 19 are moved to acquire and measure an image projected on the photoelectric detector 21 at a predetermined diopter pitch ΔD over the entire range that can be measured by the eye optical characteristic measuring apparatus. For example, if the entire measurement range is ± 20 diopters (hereinafter referred to as D) and the diopter pitch ΔD is 1D, 41 images are acquired.

  (Step 02) Each image is stored in the storage unit 27 in association with the diopter value at the time of image acquisition, and further, shape determination is performed for each image, and the shape of the image and the diopter value are associated with each other. When there is no astigmatism in the eye to be examined, the image received by the photoelectric detector 21 decreases from a blurred large circle and increases in luminance. When the minimum circle elapses, the circle increases and the luminance decreases.

  Further, when the eye to be examined includes astigmatism, the image received by the photoelectric detector 21 becomes smaller from a blurred large circle, the luminance increases, and the shape becomes an ellipse. As shown in FIG. 5, a minimum circle (minimum circle of confusion) passes through a flat ellipse, and after passing through the circle of minimum circle of confusion, an ellipse having an inclination different from that of the ellipse is formed, and further, a circle is formed. As it increases, the brightness decreases. FIG. 5 shows images with diopters around the minimum scattering circle.

  Hereinafter, a case where the eye to be examined includes astigmatism will be described.

  For each acquired image, shape determination is performed by the received light image determination program. An example of the shape determination will be described with reference to FIG.

  An XY coordinate axis is set on the light receiving surface of the photoelectric detector 21, and the shape of the image 31 formed on the XY coordinate axis is determined by detecting Xmax and Xmin and Ymax and Ymin. For example, (Xmax−Xmin) = ΔX and (Ymax−Ymin) = ΔY are obtained, and the value of ΔY / ΔX (= K) is used as the shape value. It is assumed that an image with K = 1 and ΔX or ΔY having a minimum value is a minimum circle of confusion. The minimum circle of confusion is identified as the most focused position in the rough measurement. The diopter value D0 for the image (best focus image) from which the minimum circle of confusion is obtained is acquired as data and recorded in the control unit 28.

  (Step 03) The front focal line and the rear focal line are obtained before and after the image where the minimum circle of confusion is obtained. For the determination of the front focal line and the rear focal line, the state where the ellipse is flattened based on Xmax and Xmin and Ymax and Ymin obtained from each image is defined as the front focal line and the rear focal line. Diopter values Df and Db for the image where the front focal line and the rear focal line are obtained are acquired as data and recorded in the control unit 28.

  (Step 04) This measurement is performed based on the diopter values D0, Df, Db. That is, the diopter value D0 is set as a target value, and the main measurement range W is set so as to include the diopter values Df and Db around the diopter value D0.

  The main measurement range W is set in advance as an initial setting, and if the number of images acquired in the main measurement range W is set to 11, for example, the main measurement diopter pitch ΔD in the main measurement range W is , W / 10. For example, in FIG. 4, if the range of the main measurement is ± 1D, the main measurement diopter pitch ΔD = 0.2D.

  The main measurement range W set in the initial setting is set by the examiner via the operation unit 30, and the set value is selected or determined based on past astigmatism data or the like.

  The measurement range W may be determined and set by the sequence program so as to include the diopter values Df and Db based on the diopter values D0, Df and Db. If the number of acquired images in the main measurement range W is set as an initial setting, the main measurement diopter pitch ΔD in the main measurement range W can be obtained by calculation based on the main measurement range W and the number of images. Further, the actual measurement diopter pitch ΔD may be set as an initial setting. In this case, the main measurement range W includes the diopter values Df and Db and is a multiple of the main measurement diopter pitch ΔD, and the number of acquired images is obtained by calculation.

  If measurement of astigmatism of the eye to be examined is not required, the measurement range W may be set near the minimum circle of confusion and does not need to include the diopter values Df and Db of the front focal line and the rear focal line.

  (Step 05) When the main measurement range W in the main measurement is set, an image projected on the photoelectric detector 21 with the main measurement range W at the main measurement diopter pitch ΔD with the target value (diopter value D0) as the center. Get and measure.

  Here, the actual measurement diopter pitch ΔD may be set to a fixed value, for example, 0.03D in advance before measurement, or the number of images to be acquired in the actual measurement range W is set by default. The numerical value of the main measurement diopter pitch ΔD may be increased or decreased according to the main measurement range W.

  Each image acquired in the main measurement is subjected to shape determination by the received light image determination program as in STEP: 02, and an image of the minimum circle of confusion (best focus image) in the main measurement range W is obtained.

  STEP: 06,07 The MTF iso-optical characteristics are calculated for the selected image.

  STEP: 06 The target gap direction profile is calculated.

  (Step 07) Further, a Depression value and a Contrast value are calculated. The calculated Depression value and Contrast value are displayed on the display unit 29.

  Here, for the calculation of eye optical characteristics such as MTF, target gap direction profile, Depression value, and Contrast value in STEP: 06, STEP: 07, STEP: 08, and 09: This is described in Japanese Patent Application No. 2000-364834 (Japanese Patent Laid-Open No. 2002-209852) (Patent Document 2) filed.

  In FIG. 7, the operation of the received light image determination program will be described with respect to the shape determination in which the image at the best focus position is selected in STEP: 02 and STEP: 05.

  (Steps 201 and 202) The highest luminance value in each image is calculated from the plurality of acquired images, and an image having each highest luminance value equal to or higher than the first slice level is selected. The selected image is shown in FIGS. 5A to 5J, for example. In the figure, FIG. 5 (F) is shown as an image of the minimum circle of confusion.

  STEP: 203 An image having the highest maximum luminance value is selected from the images selected in STEP: 202.

  STEP: 204, 205 It is determined whether or not there is one image selected in STEP: 203. If there is one image, the number of pixels indicating a luminance value equal to or higher than the first slice level is obtained for the image.

  STEP: 206, 207 For the shape formed by the pixel obtained in STEP: 205, the shape is determined based on the size in two orthogonal directions, for example. For example, it is determined whether or not the size is approximately equal in the horizontal and vertical directions on the coordinates of the light receiving surface of the photoelectric detector 21. If it is determined that the size is approximately equal, the selection is made at STEP 203. One image is selected as a calculation target image (measurement image). For example, FIG. 5 (F) is selected.

  STEP: 208 Next, in STEP: 206, when the shapes formed by the pixels are not substantially equal in the horizontal and vertical directions, the images before and after the image selected in STEP: 205 are respectively The number of pixels equal to or higher than the first slice level is obtained.

  STEP: 209 The shape formed by the pixel obtained in STEP: 208 is determined. The horizontal and vertical sizes are obtained on the coordinates of the light receiving surface, and the shape is determined from the horizontal and vertical sizes. For example, the ratio of the sizes in the horizontal and vertical directions is determined as the shape determination.

  (Step 210) For each selected image, the image having the closest size in the horizontal and vertical directions, for example, the image having the obtained ratio closest to 1 is determined as the calculation target image.

  Further, when there are a plurality of images selected in STEP: 203, the calculation target image is determined by the subsequent operation of STEP: 211.

  STEP: 211 The number of pixels equal to or higher than the first slice level is obtained for each of the selected plurality of images.

  STEP: 212 The image having the smallest number of pixels is selected.

  (Steps: 213, 214) In the selected image, it is determined whether the shapes formed by the pixels at the first slice level or higher have substantially the same size in the horizontal and vertical directions on the coordinates. If it is determined, one image selected in STEP: 212 is determined as a calculation target image.

  STEP: 215, 216 For the image selected in STEP: 212, if the shape formed by the pixels at the first slice level or higher is not substantially the same size in the horizontal and vertical directions, the image before and after that obtained in STEP: 212 The number of pixels equal to or higher than the first slice level is obtained for the image, and the horizontal and vertical sizes are determined on the coordinates for the shape formed by the pixels, and the shape is determined from the horizontal and vertical sizes.

  (Step 217) For each of the selected images, the closest image in the horizontal and vertical directions is determined as the calculation target image.

  Based on the above-described image determination, an image having the best focus state and closest to the minimum circle of confusion is selected as the calculation target image. Therefore, the influence of the individual difference of the examiner on selection of the calculation target image is eliminated.

  The selected image is displayed on the display unit 29 and confirmed by the examiner, and the optical characteristics of the eye such as PSF are calculated in STEP: 06 to STEP: 09, or the calculation is executed immediately when selected. The

  Note that the horizontal and vertical sizes on the coordinates of STEP: 206, 209, 213, 216, etc. can be determined by various methods. In addition to the method of comparing the horizontal and vertical sizes of the shape formed by the pixels at the first slice level or higher in the selected image, for example, the centroid position of the image formed by the pixels is obtained and the centroid position is determined. A method of comparing the major axis and the minor axis of the shape centering on the pixel (the shape of the pixel may or may not be approximated to an ellipse) may be used.

  Next, referring to FIG. 8, the operation of the received light image determination program for determining the shape of the image and selecting the image of the front and rear focal lines in STEP: 03 will be described.

  STEP: 301 All images are selected for the diopter on the near side from the image of the main measurement target value.

  STEP: 302 to STEP: 304 For each image, Xmax and Xmin and Ymax and Ymin at the first slice level are obtained (see FIG. 6).

  STEP: 305, STEP: 306 A normal is set at the midpoint of the line segment connecting the coordinates (Xmax, Ymax) and the coordinates (Xmin, Ymin), and the luminance value on the normal in each image is equal to or lower than the first slice level. Find the points P and S.

  (Step 307) An image with the shortest line segment PS is selected, and this image is set as a front focal line image.

  STEP: 308 All the images are selected for the diopter on the rear side of the image of the main measurement target value.

  STEP: 309 The same processing as STEP: 302 to STEP: 306 is performed.

  (Step 310) An image with the shortest line segment PS is selected, and this image is set as a rear focal line image.

  As described above, the minimum circle of confusion can be selected without including the individual differences of the examiners, and high-precision eye optical characteristics can be measured from the minimum circle of confusion.

  Further, as described above, the accurate minimum diopter circle diopter, front focal line diopter, and rear focal line diopter are obtained from the image processing, and the major axis inclination angle is also obtained from the front focal line and rear focal line images. be able to. Therefore, it is possible to measure the eye refractive power and the astigmatism measurement of the eye to be examined without being influenced by individual differences among examiners.

  That is, the eye refractive power of the eye to be examined is measured as a diopter value in an accurate minimum circle of confusion.

Next, astigmatism measurement, the difference between the refractive index of the front focal line and the refractive index of the rear focal line is measured as the astigmatic degree C, and the astigmatic axis of the front focal line is a straight line indicating the inclination in the image. That is, the straight line connecting the two points (Xmax, Ymax) and (Xmin, Ymin). Each is obtained by obtaining tan ⁻¹ (ΔY / ΔX) from the image of the rear focal line. Thus, the refractive index S, astigmatism C, and astigmatism axis A are calculated from the captured image.

  When the refractive index S, the astigmatism C, and the astigmatism axis A are measured for the eye to be examined, since the luminous flux of the target image projected onto the eye to be examined is point-like, the reflected luminous flux is corneal shape, edema, and turbidity of the crystalline lens. The eye refractive power and the astigmatism can be measured regardless of the condition of the eye to be examined.

  Next, a second embodiment will be described with reference to FIGS.

  Although the main measurement range W is set in the above STEP: 04 and STEP: 05 and the main measurement is executed, a sufficient minimum circle of confusion may not be obtained depending on the eye to be examined. In this case, as shown in FIG. 3, finer measurement (fine measurement) is performed at STEP: 051 and STEP: 052. The condition for shifting to fine measurement is when the difference between the image that can be determined to be the minimum circle of confusion and the adjacent image does not satisfy a predetermined condition (for example, a difference in brightness, a difference in diameter, or the like). .

  The fine measurement range is set using the diopter of the best focus image obtained in STEP 05 as the target value. The fine measurement range in this case may be determined in advance by initial setting, or may be obtained by calculation such as setting a predetermined multiple according to the value of the actual measurement diopter pitch ΔD. For example, as shown in FIG. 4, eleven images are acquired with a fine measurement range of ± 0.2D and a fine diopter pitch ΔD of 0.04D. The received light image determination program is executed on the 11 acquired images, and the minimum circle of confusion in the fine measurement range, that is, the best focus image is selected by the action shown in FIG. STEP: 06 to STEP: 09 are executed for the selected best focus image, the light intensity distribution of meridians in a plurality of directions is obtained, and the eye optical characteristics of the eye to be examined are calculated based on the light intensity distribution.

  In the above embodiment, the rough measurement, the main measurement, and the fine measurement are automatically performed by the program without any intervention by the examiner. However, as the third embodiment, the rough measurement, the main measurement, and the main measurement are performed. In the process of shifting from fine measurement to precise measurement, the examiner may be able to confirm the measurement state, or set or change the measurement conditions.

  For example, as an initial setting before starting the measurement, when the rough measurement is completed, the program is set in a standby state, and the program is continued by instructing by the examiner, so that the main measurement is started.

  In the standby state, the main measurement range W selected by the rough measurement, the main measurement diopter pitch ΔD, the acquired image, and the like can be confirmed on the display unit 29. Measurement conditions such as the main measurement range W or the main measurement diopter pitch ΔD can be changed.

  Therefore, the examiner can select whether to check the result of the rough measurement and continue the measurement, or to change the measurement condition such as the main measurement range W or the main measurement diopter pitch ΔD. It is. By adding the judgment of the examiner, it is possible to avoid unnecessary waste such as unnecessarily widening the measurement range, or finely measuring the measurement diopter pitch ΔD unnecessarily, or measuring only the necessary part with high accuracy. Efficiency.

  As described above, in the present invention, the measurement range for acquiring the calculation target image is automatically set, the light intensity distribution image as the calculation target of the eye optical characteristics is selected under the same conditions, and the selection is an individual difference of the examiner. Therefore, the measurement is performed in a very short time, the measurement time can be shortened, and the burden on the subject is reduced.

It is a schematic block diagram which shows embodiment of this invention. It is a figure which shows an example of the aperture stop used for this Embodiment. It is a flowchart which shows the operation | movement for measuring the eye optical characteristic in embodiment of this invention. It is explanatory drawing about the setting of the measurement range in embodiment of this invention. (A), (B), (C), (D), (E), (F), (G), (H), (I), and (J) are explanatory diagrams showing acquired images in the embodiment of the present invention. It is explanatory drawing of the shape judgment about an acquired image. It is a flowchart which shows the operation | movement which selects the calculation target image in ocular optical characteristic measurement. It is a flowchart which judges the image of a front focal line and a back focal line by shape judgment from an acquired image.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Eye to be examined 2 Projection optical system 3 Light reception optical system 4 Light source part 5 Light source 14 Projection system aperture stop 15 Fixation target 17 Fixation target system 19 Focusing lens 21 Photoelectric detector 22 Light reception system aperture stop 26 Signal processing part 27 Storage part 28 Control unit 29 Display unit 30 Operation unit

Claims (9)

  A target projection optical system for projecting a target image on the fundus of the subject's eye, a light receiving unit for receiving the target image from the target image projection system reflected from the fundus of the subject's eye, and the light receiving unit An ophthalmic optical system comprising a control unit that can acquire a plurality of target images in association with diopters, determines a shape of the plurality of acquired images, and associates the shape with the diopter Characteristic measuring device.   The ophthalmic optical characteristic measuring apparatus according to claim 1, wherein the control unit sets a measurement range based on a plurality of acquired image shapes.   2. The ophthalmic optical characteristic measurement according to claim 1, wherein the control unit recognizes and selects a minimum circle of confusion from a plurality of acquired images based on determination of an image shape, and sets the minimum circle of confusion as a measurement range reference. apparatus.   The ophthalmic optical characteristic measuring apparatus according to claim 3, wherein a measurement range is set by the control unit centering on an image of the minimum circle of confusion.   The ophthalmic optical characteristic measuring apparatus according to claim 1, wherein the control unit is capable of selecting an image that can be recognized as a minimum circle of confusion, a front focal line, and a rear focal line from the obtained shape determinations of the plurality of images.   3. The ophthalmic optical characteristic measuring apparatus according to claim 2, wherein an image is acquired at a predetermined diopter pitch within a set measurement range, and an image of a minimum circle of confusion is selected from the acquired image by shape determination.   The ophthalmic optical characteristic measuring apparatus according to claim 6, wherein the control unit obtains a light intensity distribution in a plurality of meridian directions of the selected minimum confusion circle image, and calculates an eye optical characteristic of the eye to be examined based on the light intensity distribution.   The ophthalmic optical characteristic measuring apparatus according to claim 6, wherein the control unit is capable of setting a diopter pitch according to a set measurement range.   The ophthalmic optical characteristic measuring apparatus according to claim 3 or 6, further comprising an operation unit capable of setting measurement conditions, wherein the measurement range can be set around the image of the minimum circle of confusion via the operation unit.

Images