JP2017056026A - Eye refractive power measuring apparatus and control method for eye refractive power measuring apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce measurement errors due to a speckle pattern by a simple structure to enable highly accurate measurements of eye refractive power even when an SLD is used as a light source for eye refractive power measurement.SOLUTION: There is provided an eye refractive power measuring apparatus, comprising: a measuring head which includes a low-coherent light source for projecting index light onto an ocular fundus of a subject eye, and which includes imaging means for imaging reflected scattered light of the index light projected onto the ocular fundus; drive means for driving the measuring head; control means for controlling the drive means such that the measuring head is placed in a predetermined position relative to the subject eye; and calculation means for calculating a value of the eye refractive power of the subject eye, based on outputs obtained by imaging the reflected scattered light while the control means moves the measuring head from the predetermined position.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an eye refraction measuring device for analyzing a fundus image of a subject eye and a method for controlling the eye refractive power measuring device.

  2. Description of the Related Art An eye refractive power measurement device that projects index light emitted from an infrared light source onto the fundus of a subject's eye and receives reflected light from the fundus of the projected index light to measure the eye refractive power of the subject's eye is known. Yes. In recent years, an ocular refractive power measuring apparatus using a super luminescence diode (hereinafter abbreviated as SLD), which is a low-coherent light source, is also known as a light source for projecting an index onto the fundus.

Patent Document 1 discloses an autorefractometer that projects an index light beam on the fundus and measures eye refractive power from a signal detected from a reflected image of the index light beam. This autorefractometer is trying to solve the problem that when the pupil of the eye to be examined is small and the measurement is performed with the center of the pupil coincident with the measurement optical axis, the index light beam is kicked by the iris and cannot be measured. .
For an eye refractive power measuring apparatus capable of measuring eye refractive power even with a small pupil diameter, it is necessary to use an SLD that is a light source having a high radiant luminous intensity per unit solid angle. However, although SLD is a low-coherent light source, it has spatial coherency. For this reason, a speckle pattern due to light interference occurs in the light source image obtained by projecting the light beam emitted from the SLD onto the fundus of the eye to be examined. When an eye refractive power measurement is performed using a measurement index image in which a speckle pattern is generated, a measurement error occurs due to the speckle pattern. In the autorefractometer disclosed in Patent Document 1, the measurement optical system is driven so that the optical axis of the measurement optical system rotates around the center of the pupil of the eye to be measured when projecting the index light beam, and this measurement error is reduced. I am trying.

JP 2005-185523 A

  Here, in order to solve the above-described problem that the measurement error due to the speckle pattern occurs, it is conventionally necessary to add a new configuration such as rotating the optical axis of the measurement system around the pupil center.

  In view of the above, an object of the present invention is to reduce the measurement error due to a speckle pattern with a simple configuration even when a low-coherent light source such as an SLD is used as an eye refractive power measurement light source, and to provide a highly accurate eye. Measure the refractive power.

In order to solve the above-described problems, an eye refractive power measurement device according to the present invention includes:
A measurement head having a low coherent light source that is a light source that projects index light onto the fundus of the eye to be examined, and an imaging unit that captures reflected and scattered light of the index light projected onto the fundus;
Driving means for driving the measuring head;
Control means for controlling the drive means so that the measuring head is in a predetermined position with respect to the eye to be examined;
Calculating means for calculating an eye refractive power value of the eye based on an output of the imaging means obtained by imaging the reflected scattered light while moving the measuring head from the predetermined position by the control means; ,
It is characterized by having.

  According to the present invention, even when an SLD is used as an eye refractive power measurement light source, a measurement error due to a speckle pattern can be reduced with a simple configuration, and highly accurate eye refractive power measurement can be performed. .

It is the schematic showing an example of the whole structure of the eye refractive power measuring apparatus which concerns on the 1st Example of this invention. It is the figure which showed the structure of the aperture plate used in the eye refractive power measuring apparatus shown in FIG. It is the figure which showed an example of the measurement light source image projected on the fundus Er. It is the figure which showed an example of the measurement ring image. It is the figure which showed the distribution of the brightness of a measurement ring image in the cross section of this ring image. It is the figure which showed the measurement ring image produced | generated by the addition average process. It is the figure which showed the brightness distribution of the measurement ring image after an addition average process in the cross section of this ring image.

[First embodiment]
The present invention will be described in detail below based on the illustrated embodiments. The following embodiments do not limit the present invention related to the scope of claims, and all combinations of features described in the embodiments are not necessarily essential to the solution means of the present invention. Absent.

  FIG. 1 is a schematic diagram showing an outline of the configuration of an eye refractive power measuring apparatus according to the first embodiment of the present invention. In the figure, the part surrounded by a solid line corresponds to the measuring head 100 of the eye refractive power measuring apparatus.

  A dichroic mirror 1 is disposed on the optical axis 101 facing the eye E in the measurement head 100. An anterior ocular segment observation objective lens 2 and a dichroic mirror 3 are disposed on the optical axis 102 in the reflection direction of the dichroic mirror 1. On the optical axis 103 in the reflection direction of the dichroic mirror 3, the imaging lens 4 and the image sensor 5 are arranged. In the present embodiment, a CCD camera is used as the image sensor 5 and is arranged at a position substantially conjugate with the vicinity of the anterior eye portion of the eye E to be examined.

  Further, a pair of anterior segment illumination light sources 26 such as LEDs that emit near-infrared light for illuminating the anterior segment of the eye to be examined are symmetrical between the examinee E and the dichroic mirror 1 with respect to the optical axis 101. Placed in position. An anterior ocular segment observation system is constituted by these optical members extending from the anterior ocular segment observation objective lens 2 to the image sensor 5.

  Further, a diaphragm plate 7 as shown in FIG. 2 is arranged in front of the imaging lens 4 on the optical axis 103. The diaphragm plate 7 is arranged so that the central opening 7 c is positioned on the optical axis 103, and has two symmetrical openings 7 a and 7 b outside the optical axis, and can be inserted into and removed from the optical axis 103. Has been. The deflecting prisms 6a and 6b are in close contact with the openings 7a and 7b, respectively. The deflection prisms 6a and 6b transmit light having a wavelength emitted from an alignment index projection light source 37, which will be described later, and have spectral characteristics that do not transmit light having a wavelength emitted from the anterior ocular segment illumination light source 26. Further, the deflecting prism 6a deflects transmitted light downward in the drawing, and the deflecting prism 6b deflects transmitted light upward in the drawing.

  On the optical axis 101 in the transmission direction of the dichroic mirror 1, an objective lens 8 for measuring eye refractive power, a perforated mirror 9, a projection aperture 10, a projection lens 11, and an eye refractive power measuring light source 12 are arranged. The eye refractive power measurement light source 12 emits near-infrared light having a wavelength of several tens of nanometers longer than the light generated from the anterior segment illumination light source 26 described above. The eye refractive power measurement light source 12 uses a super luminescence diode (hereinafter referred to as SLD) which is a low coherent light source that emits low coherent light. That is, the eye refractive power measurement light source 12 constitutes a low coherent light source in this embodiment. A ring diaphragm 13, a conical prism 14, a lens 15, and an image sensor 16 are disposed in the reflection direction of the perforated mirror 9. The ring diaphragm 13 has an opening on the ring around the optical axis. In this embodiment, a CCD camera or the like is used for the image sensor 16. An eye refractive power measurement light projection system for projecting index light onto the fundus is constituted by an optical member extending from the eye refractive power measurement objective lens 8 to the eye refractive power measurement light source 12. Further, the eye refractive power measurement includes the imaging element 16 that is an imaging unit that captures the reflected and scattered light of the index light projected onto the fundus as an index image by the optical element from the eye refractive power measurement objective lens 8 to the imaging element 16. A light receiving system is configured.

  The eye refractive power measurement light source 12 and the image sensor 16 are provided with measurement system driving means 17 for moving and driving these components in the optical axis direction according to the refractive power of the eye E to be examined.

  On the other hand, a lens 18 and a visible reflection mirror 19 are disposed on the optical axis 104 in the transmission direction of the dichroic mirror 3. Further, a fixation target projection lens 20, a fixation target 21, and a fixation target illumination light source 22 are disposed on the optical axis 105 in the reflection direction of the visible reflection mirror 19. These structures constitute the fixation means in the present embodiment. The fixation target projection lens 20 can be moved in the direction of the optical axis 105 by the fixation target lens driving means 23. In this embodiment, a white LED is used as the fixation target illumination light source 22. Fixation target projection that presents a fixation target for fixation of the eye to be examined by optical members from the observation objective lens 2 to the fixation target projection lens 20, the fixation target 21, and the fixation target illumination light source 22. The system is configured.

  Furthermore, a lens 24, an alignment index plate 25, and an alignment index projection light source 37 are disposed on the optical axis 106 in the transmission direction of the visible reflection mirror 19. The dichroic mirror 1 transmits light having a wavelength emitted from the eye refractive power measurement light source 12 and reflects light having a wavelength emitted from the anterior segment illumination light source 26 and light having a wavelength emitted from the alignment index projection light source 37. have. The dichroic mirror 3 has a characteristic of transmitting visible light and acting as a half mirror for light having a wavelength emitted from the alignment index projection light source 37.

  The measuring head 100 is configured by the anterior ocular segment observation system, the fixation target projection system, the eye refractive power measurement light projection system, the eye refractive power measurement light receiving system, and the like described above. The measuring head 100 is supported by measuring head driving means 36, and is moved and driven by the measuring head driving means 36 in the three axial directions. The measuring head driving unit 36 as a driving unit in the present embodiment performs alignment by controlling the position of the measuring head 100 with respect to the eye E. By this alignment operation, the measuring head 100 takes a predetermined position with respect to the eye to be examined.

  The image sensor 5 and the image sensor 16 are connected to an A / D converter 27 and an A / D converter 28, respectively. Each output is connected to an image memory 29 and an image memory 30, respectively. Furthermore, these components are connected to the control means 31 that performs all the controls of the eye refractive power measuring apparatus according to the present embodiment. More specifically, the fixation target illumination light source 22 that illuminates the fixation target 21 of the above-described fixation target projection system is connected to a fixation target light source control unit 32, and the fixation target light source control unit 32 is a control unit. 31 is connected. The control means 31 includes an eye refractive power measurement light source 12, an operation means 33 provided with a measurement start switch, a switch for operating a drive means, and the like, and the eye refractive power measurement light source 12 and the image sensor 16 in the optical axis direction. A measuring system driving means 17 for moving is connected. A monitor 35 and a measurement head driving unit 36 are also connected to the control unit 31. The control unit 31 controls the measurement head driving unit 36, the image sensor 16, and other components.

Next, the operation of the intraocular pressure measurement device according to the first embodiment will be described.
First, the examiner operates an alignment operation rod provided in the operation means 33 so that the right eye E of the examinee is displayed on the monitor 35, and roughly aligns the examinee's eye with the measuring head 100. . At this time, the light beam from the fixation target 21 illuminated by the fixation target illumination light source 22 is transmitted through the dichroic mirror 3 via the fixation target projection lens 20, the visible reflection mirror 19, and the lens 18 to observe the anterior segment. It is guided to the eye E through the objective lens 2 and the dichroic mirror 1. As a result, the fixation target 21 is presented to the eye E.

  Next, when a measurement start switch provided in the operation means 33 is pressed, the control means 31 starts a measurement operation. When the measurement is started, the eye E is illuminated by the anterior segment illumination light source 26. The reflected and scattered light from the periphery of the anterior segment of the illumination light is reflected by the dichroic mirror 1 and is made substantially parallel by the anterior segment observation objective lens 2. Thereafter, the reflected scattered light is reflected by the dichroic mirror 3, passes through the opening 7 c of the aperture plate 7, and forms an image on the image sensor 5 by the imaging lens 4. The output signal output from the image sensor 5 based on the image is converted into a digital signal by the A / D converter 27. The digital signal is converted into an image via the control means 31 and is displayed on the monitor 35 as an anterior segment image. At the same time, when the data of the anterior ocular segment image data converted into the digital signal is stored in the image memory 29, the control means 31 further extracts the pupil of the right eye to be inspected from the stored anterior segment image data. Further, the pupil center position is detected.

  In this pupil center position detection method, for example, when the anterior eye portion of the eye to be examined is sufficiently illuminated, the brightness of the anterior eye portion image is darkest in the pupil, and becomes brighter in the order of the iris and sclera. Therefore, the boundary of the pupil can be obtained by binarizing the image with an appropriate threshold value, and the pupil center position can be calculated from it.

  When the pupil center position is detected, the control means 31 calculates a deviation amount in a plane perpendicular to the optical axis in the positional relationship between the optical axis of the measuring head 100 and the pupil center position. Then, it is determined whether or not the calculated deviation amount between the pupil center position and the apparatus measurement optical axis is within a preset tolerance.

  When the amount of deviation between the pupil center position and the apparatus measurement optical axis is not within the tolerance, the control unit 31 controls the measurement head driving unit 36 so that the optical axis of the measurement head 100 and the pupil center position coincide. After the measurement head 100 is driven, it is determined again whether the deviation amount between the pupil center position and the apparatus measurement optical axis is within the tolerance. The above is the pupil center auto-alignment.

  If it is determined that the amount of deviation between the pupil center position and the apparatus measurement optical axis is within the allowable range, the process proceeds to the next step.

  The control unit 31 turns on the alignment index projection light source 37 via the alignment index projection light source control unit 38. The light emitted from the alignment index projection light source 37 illuminates the alignment index plate 25 to become an alignment index beam, which passes through the lens 24, the visible reflection mirror 19, and the dichroic mirror 3, and is obtained by the anterior ocular segment observation objective lens 2. A substantially parallel light beam is obtained. The substantially parallel light beam is reflected by the dichroic mirror 1 and then reaches the eye E to be examined.

  When the alignment index light beam reaches the eye E as the index light, the alignment index light beam is reflected by the cornea Ec of the eye E, and the corneal reflection index image of the reflected light beam is positioned at the midpoint of the corneal curvature center and the corneal vertex. Form. The alignment index light beam reflected by the cornea Ec is reflected by the dichroic mirror 1, becomes substantially parallel light by the anterior ocular segment observation objective lens 2, and is deflected along the optical axis 103 by the dichroic mirror 3. After the deflection, the luminous flux is divided into three luminous fluxes by the three apertures 7c, 7a and 7b of the diaphragm plate 7 with the deflecting prisms 6a and 6b, and then these luminous fluxes reach the image pickup device 5 by the imaging lens 4. The image is taken together with the anterior eye image of the eye to be examined, digitized by the A / D converter 27 and stored in the image memory 29. Further, a spot image obtained from the three light beams is detected from the image data stored in the image memory 29.

  Next, the relative position between the measuring head 100 and the eye E is detected from the barycentric positions of the detected three spot images and their relative positions. From the detection result, it is determined whether or not the measurement head 100 and the eye E to be examined are in a positional relationship within a range allowed for the predetermined positional relationship. When the positional relationship between the measurement head 100 and the eye E is not within the allowable range, the control unit 31 controls the measurement head driving unit 36 so that the measurement head 100 and the eye E are in a predetermined positional relationship. After the operation of the measurement head driving unit 36, three spot images are detected again, and it is determined whether or not the measurement head 100 and the eye E are in a predetermined positional relationship. That is, in the present embodiment, auto alignment is performed using three spot images.

  If it is determined that the positional relationship between the measuring head 100 and the eye E is within the allowable range, that is, is in a predetermined position with respect to the eye E, the process proceeds to the next step. Next, the control means 31 prompts the eye E to be fogged.

  In the cloud operation, first, the fixation target illumination light source 22 is turned on to illuminate the fixation target 21. The light beam from the fixation target 21 is converted into substantially parallel light through the fixation target projection lens 20, the visible reflection mirror 19, the lens 18, the dichroic mirror 3, and the observation objective lens 2, and presented to the eye E to be examined. . The eye E fixes an image of the presented fixation target 21. Subsequently, the control means 31 turns on the eye refractive power measurement light source 12. The light emitted from the eye refractive power measurement light source 12 reaches the dichroic mirror 1 through the projection lens 11, the projection aperture 10, the hole of the perforated mirror 9, and the eye refractive power measurement objective lens 8. The light further passes through the dichroic mirror 1 and projects a measurement light source image that is an image of the eye refractive power measurement light source 12 onto the fundus oculi Er of the eye E to be examined. The light beam reflected and scattered using the measurement light source image projected onto the fundus Er of the eye E as the secondary light source is emitted from the pupil Ep and the cornea of the eye E. The emitted light beam passes through the dichroic mirror 1, is collected by the eye refractive power measurement objective lens 8, and is reflected by the peripheral portion of the perforated mirror 9. The reflected emitted light beam is further limited by the ring diaphragm 13, passes through the conical prism 14 and the lens 15, reaches the image sensor 16, and is imaged as a measurement ring image.

  The output of the image sensor 16 based on the measurement ring image is digitized by the A / D converter 28 and recorded in the image memory 30. In addition, based on the obtained measurement ring image, the control means 31 calculates the refractive power D1 of the eye E before clouding by a known method. In actual refractive power calculation, for example, the area center of gravity of the ring part is calculated from the cross-sectional image that is the brightness distribution of the measurement ring image, and the area of the ring part from the cross-sectional image obtained by changing the cross-sectional position of the measurement ring image one after another. Repeat the calculation of the center of gravity. An approximate ellipse is obtained by the least square method from the obtained barycentric positions of the plurality of ring portions, and the refractive power D1 of the eye E is obtained from the size of the approximate ellipse or the ratio of the major axis to the minor axis.

  After calculating the refractive power D1, the control unit 31 causes the fixation target lens driving unit 23 to move the fixation target projection lens 20 in the optical axis direction of the optical axis 105. When the fixation target projection lens 20 is moved, the fixation target 21 is positioned at a position that is +0.5 diopters away from the conjugate position on the optical axis 105 before the cloud fog for which the refractive power D1 is obtained. At the same time, the measurement system driving unit 17 moves the eye refractive power measurement light source 12 and the image sensor 16 in the optical axis direction according to the detected refractive power D1. After the movement of these optical members, the eye refractive power measurement light source 12 is turned on again to project a light beam on the fundus Er of the eye E. The obtained reflected and scattered light from the fundus Er is imaged again by the image sensor 16, and the refractive power D2 is calculated. Then, the fixation target lens driving unit 23 is controlled so that the fixation target 21 is located at a position further +0.5 diopter than the conjugate position on the optical axis 105 for which the refractive power D2 is obtained. At the same time, the measurement system driving means 17 moves the eye refractive power measurement light source 12 and the image sensor 16 in the optical axis direction according to the detected refractive power D2. The above operation is repeated until the refractive power of the eye E to be examined cannot follow the optical position of the fixation target 21 on the optical axis 105. By doing so, the diopter adjustment of the eye E can be relaxed, and a cloud (distant vision) state can be obtained.

  That is, in the cloud operation, the distance when the fixation target is presented to the eye E is gradually moved far away to perform the cloud. The configuration for performing the above operations corresponds to the cloud fog means in the present embodiment. Note that the control unit 31 performs the above-described three-point spot auto-alignment while the cloud operation of the eye E is performed, and the positional relationship between the eye E and the measuring head 100 is kept constant. I keep it.

  When the cloud is completed, the control means 31 performs the main measurement of the eye refractive power measurement.

  In this measurement, the control means 31 first stores the current positional relationship between the eye E to be examined and the optical axis of the measurement head 100 as the alignment state (a) by the above-described three-point spot auto-alignment. In the alignment state, the measuring head 100 is at a predetermined position with respect to the eye E. In this alignment state, the eye refractive power measurement light source 12 is turned on, and a measurement light source image that is an image of the eye refractive power measurement light source 12 is projected onto the fundus Er of the eye E through the above-described eye refractive power measurement light projection system. . As illustrated in FIG. 3A, a speckle pattern appears in the measurement light source image 37 (a) because the eye refractive power measurement light source 12 is an SLD. The light beam reflected and scattered by using the measurement light source image 37 (a) projected onto the fundus Er of the eye E as the secondary light source is emitted from the pupil Ep and the cornea of the eye E. The emitted light beam reaches the image pickup device 16 through the above-described eye refractive power measurement light receiving system, and is picked up as a measurement ring image 38 (a) as shown in FIG. 4 (a).

  Here, the brightness distribution of the measurement ring image on the y-axis indicated by the arrow in FIG. 4A is shown as a cross-sectional image 39 (a) in FIG. 5A in the cross section of the ring image. Due to the speckle pattern, brightness unevenness has occurred in the cross-sectional image 39 (a), which is the brightness distribution of the measurement ring image. The positions indicated by reference numerals 40 (a) and 41 (a) in FIG. 5 (a) are the positions of the area centroids determined from the ring portion of the cross-sectional image 39 (a). The area centroid positions 40 (a) and 41 (a) are affected by the speckle pattern.

  Here, the cross-sectional position of the measurement ring image 38 (a) is sequentially changed, the area centroid position on the measurement ring image 38 (a) is obtained over the entire circumference of the ring image, and an approximate ellipse is obtained from the area centroid by the least square method. It is also possible to calculate. However, in this case, an approximate ellipse with a poor correlation coefficient is caused by the speckle pattern, and the measurement accuracy is lowered.

  Therefore, in this embodiment, the control means 31 is different from the alignment state (a), and the positional relationship between the eye E and the optical axis of the measuring head 100 is set in the horizontal direction in a plane perpendicular to the optical axis 101. The measuring head driving means 36 is controlled so as to be slightly shifted. That is, the reflected and scattered light from the eye E is imaged while moving from a predetermined position. As for the obtained alignment state, the measurement light source image 37 (b) obtained in the alignment state (b) is shown in FIG. 3 (b), the measurement ring image 38 (b) is shown in FIG. 4 (b), and the brightness of the ring image. A cross-sectional image 39 (b) showing the distribution is shown in FIG. 5 (b). By shifting the positional relationship between the eye E to be examined and the optical axis of the measuring head 100, the incident angle of the measurement light beam from the eye refractive power measurement light source 12 to the fundus Er changes, so that the speckle pattern also changes. Yes. That is, the brightness fluctuation related to the speckle noise shown in the cross-sectional image 39 (b) which is the brightness distribution of the ring image in FIG. 5 (b) changes from the cross-sectional image 39 (a).

  As described above, when the eye refractive power is calculated only from the measurement ring image 38 (a) in the alignment state (a), the measurement accuracy is deteriorated due to the influence of the speckle pattern. Therefore, in this embodiment, the control unit 31 gradually shifts the positional relationship between the eye E and the optical axis of the measuring head 100 in the horizontal direction, that is, sequentially changes the alignment of the measuring head 100 with respect to the eye E. I am going to do that. At that time, the alignment state (a), the alignment state (b), the alignment state (c),..., The alignment state (n), and the n measurement ring images 38 (a) to 38 (n) are examined. An image is captured and output as reflected scattered light from E. During the sequential change of the alignment, or the n measurement ring images, which are the outputs obtained according to the movement of the measurement head 100 to be changed sequentially, an averaging process is performed to affect the influence of the speckle pattern. A ring image is generated as one lost measurement index image. The generation of the ring image is executed by a module that functions as a generation unit in the control unit 31. The eye refractive power value is calculated using the ring image thus obtained. The calculation of the eye refractive power value is a calculating means for calculating the eye refractive power value of the eye to be examined based on the output of the imaging means obtained by imaging the reflected scattered light while moving the measuring head 100 from a predetermined position. It is executed by a module that functions as:

  6 and 7 show the ring image 42 generated by the averaging process from the measurement ring images 38 (a) to 38 (n) taken when the alignment state is shifted, and the y-axis of the brightness of the ring image. Cross-sectional images 43 that are distributions of directions are shown. As shown in these drawings, since the image obtained by shifting the alignment state is subjected to the averaging process, the influence of the speckle pattern is reduced. As a result, the elliptical approximation of the ring image can be performed without being affected by the speckle pattern, and the eye refractive power can be measured with high accuracy.

  In the first embodiment described above, the eye refractive power measurement light source 12 which is an SLD is arranged in the direction of the hole of the perforated mirror 9, and the ring stop 13 and the conical prism 14 are arranged in the reflection direction of the perforated mirror 9. , And the image sensor 16 were arranged. However, the aspect of the present embodiment is not limited to this. For example, in the reflection direction of the perforated mirror, an eye refractive power measurement light source 12 that is an SLD is disposed behind the ring lens or the prism so that the eye to be inspected. A ring-shaped measurement index image may be projected onto the fundus Er of E. In this case, the imaging element 16 may be arranged at a position through a lens or the like in the direction of the hole of the perforated mirror 9, and a ring index image may be captured as a measurement image.

  The above-described operation for acquiring the measurement index image is preferably performed after the above-described cloud fog operation is completed. That is, it is preferable to control the measurement head driving means 36 to keep the alignment in a constant state while driving the above-described cloud fog means, and to generate a ring image and calculate the eye refractive power value after the cloud fog is completed. .

[Second Example]
In the first embodiment described above, the state is sequentially changed to the alignment states (a) to (n), the measurement ring images in the respective alignment states are taken, and the averaging process is performed on these images to influence the speckle pattern. Reduced. On the other hand, in the second embodiment, while the alignment state is sequentially changed to the states (a) to (n), the eye refractive power measurement light source 12 is kept on, and the reflected scattered light from the fundus Er is used. A certain measurement light beam is continuously imaged by the image sensor 16. That is, while the alignment of the measuring head 100 with respect to the eye E is sequentially changed, signal accumulation in the image sensor 16 is continued. With this configuration, a measurement ring image that is not affected by the speckle pattern equivalent to the ring image 42 shown in FIG. 6 can be taken, and high-precision eye refractive power measurement can be performed.

  At this time, the light emission amount of the eye refractive power measurement light source 12 is controlled according to the accumulation time in the image sensor 16 so as not to saturate the captured measurement ring image.

[Third embodiment]
In the first embodiment and the second embodiment, the measurement ring image is captured by sequentially shifting the alignment state of the measurement head 100 with respect to the eye E to be examined in the horizontal direction. However, the direction in which the alignment state is shifted is not limited to the horizontal direction and may be the vertical direction. Alternatively, the alignment state may be shifted with respect to the optical axis of the eye E so that the optical axis 101 of the measuring head 100 draws a concentric circle. That is, the sequential change of the alignment between the eye E and the measurement head 100 performed when obtaining a plurality of index images is performed by the light of the measurement head 100 when the alignment having a predetermined positional relationship between them is initially obtained. This is performed in an arbitrary direction inside a predetermined range in a plane perpendicular to the axis.

  Furthermore, the astigmatic axis direction may be calculated from the measurement ring image obtained at the time of cloud fog, and the alignment state may be shifted in the weak principal meridian direction of astigmatism. By doing so, the amount of movement of the image of the eye refractive power measurement light source 12 projected onto the fundus Er on the fundus Er can be minimized.

  Further, there is provided means for obtaining a pupil diameter and an open state of the eye E from an observation image of the eye E imaged by the imaging device 5 of the anterior ocular segment observation system, and determining a shift amount of the alignment state according to the pupil diameter. It may be provided. By providing the means and shifting the alignment state, it is possible to prevent the measurement light beam from being blocked by the pupil of the eye E and to avoid a decrease in measurement accuracy. In this case, the pupil diameter detecting means for detecting the pupil diameter is arranged as one module of the control means 31. The control means 31 further determines the amount of movement when the alignment of the measuring head 100 is sequentially moved with respect to the eye to be examined based on the detected pupil diameter.

  That is, the configuration described as the present embodiment corresponds to providing an astigmatism axis detecting unit that detects the weak principal meridian direction of astigmatism as an astigmatism axis from the value of eye refractive power based on the measurement index image. In this case, the detection of the astigmatism axis direction is performed based on the measurement ring image obtained at that time by performing the preliminary measurement by executing the imaging of the reflected scattered light when performing cloud fog.

  In the ocular refractive power measuring apparatus according to the embodiment described above, by shifting the alignment position, the projection angle of the measurement light on the fundus changes and the speckle pattern also changes. That is, a plurality of index images are taken while shifting the alignment, one measurement index image is generated from the plurality of index images, and the eye refractive power of the eye to be examined is calculated from the measurement index images. As a result, the influence of speckle noise is reduced and the measurement can be performed with high accuracy without complicating the apparatus.

  More specifically, a plurality of images are picked up by the image pickup means while the alignment is changed, and the plurality of images are added and averaged to generate one measurement index image. By doing in this way, the influence of the speckle pattern of the measurement index image after generation can be reduced, and the brightness resolution of the image before the averaging process can be fully utilized.

  Alternatively, one measurement index image may be generated by continuing the accumulation by the imaging unit while changing the alignment. By doing in this way, it is not necessary to add a memory required at the time of generation, and the step of the averaging process can be omitted.

  Moreover, the eye refractive power measuring apparatus described above has a fog means. For the processing of cloud fog, at the time of preliminary measurement during cloud fogging, the alignment state is kept constant, and after the cloud fog is completed, one measurement index image is output from the output from the imaging means while sequentially changing the alignment with respect to the eye to be examined. Is preferably generated. By doing in this way, the whole measurement time can be shortened and the load on the subject can be reduced, so that stable measurement is possible. Further, in this case, it is further possible to calculate the astigmatic weak principal meridian direction of the eye refractive power value during preliminary measurement in the cloud fog, and to change the alignment change direction after the cloud fog is completed as the weak principal meridian direction of astigmatism. preferable. By doing so, the amount of movement of the image of the measurement light source on the fundus can be minimized, and stable measurement can be performed.

  Furthermore, as described above, it is preferable to determine the amount of movement for sequentially moving the position of the measurement head relative to the eye to be examined according to the detected pupil diameter. By doing so, the measurement light is not blocked by the pupil of the eye to be examined, and it is possible to avoid a decrease in measurement accuracy.

(Other examples)
The present invention supplies a program that realizes one or more functions of the above-described embodiments to a system or apparatus via a network or a storage medium, and one or more processors in a computer of the system or apparatus read and execute the program This process can be realized. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

DESCRIPTION OF SYMBOLS 1 Dichroic mirror 2 Objective lens for anterior ocular segment observation 3 Dichroic mirror 4 Imaging lens 5 Imaging element 6a, 6b Deflection prism 7 Diaphragm plate 8 Eye refractive power measuring objective lens 9 Hole mirror 10 Projection aperture 11 Projection lens 12 Eye refraction Force measurement light source 13 Ring diaphragm 14 Conical prism 16 Image sensor 17 Measurement system drive means 20 Fixation target projection lens 21 Fixation target 22 Fixation target illumination light source 23 Fixation target lens drive means 25 Alignment index plate 27 A / D converter 31 Control means 32 Fixation target light source controller 33 Operation means 35 Monitor 36 Measuring head drive means E Eye Ec Cornea Er Fundus

Claims (19)

A measurement head having a low coherent light source that is a light source that projects index light onto the fundus of the eye to be examined, and an imaging unit that captures reflected and scattered light of the index light projected onto the fundus;
Driving means for driving the measuring head;
Control means for controlling the drive means so that the measuring head is in a predetermined position with respect to the eye to be examined;
Calculating means for calculating an eye refractive power value of the eye based on an output of the imaging means obtained by imaging the reflected scattered light while moving the measuring head from the predetermined position by the control means; ,
An eye refractive power measuring device comprising: Further comprising generating means for generating a ring image based on the output of the imaging means obtained by imaging the reflected scattered light while moving the measuring head from the predetermined position by the control means;
The eye refractive power measurement apparatus according to claim 1, wherein the calculation unit calculates an eye refractive power value of the eye to be examined based on the generated ring image.   The generating unit generates a plurality of images based on the output of the imaging unit obtained by imaging the reflected scattered light while moving the measuring head from the predetermined position by the control unit, and the generated The eye refractive power measurement apparatus according to claim 2, wherein the ring image is generated by performing an averaging process on the plurality of images.   The generation unit generates the ring image based on an output of the imaging unit obtained by continuously storing the reflected scattered light in the imaging unit while moving the measuring head from the predetermined position by the control unit. The eye refractive power measuring apparatus according to claim 2. Fixation means for presenting a fixation target to the eye to be examined to promote fixation;
Cloud means for moving the distance to present the fixation target to the eye to be examined in the distance, and further,
The control means holds the measuring head in a predetermined position while the clouding means is being driven,
The eye refractive power measurement apparatus according to claim 2, wherein the generation unit generates the ring image after the cloud is completed. Astigmatism axis detecting means for detecting a weak principal meridian direction of astigmatism from the eye refractive power value based on the ring image,
The imaging means performs preliminary measurement of imaging the reflected scattered light when performing the cloud fog,
6. The ocular refractive power measuring apparatus according to claim 5, wherein the control means sets the direction in which the measuring head is moved from the predetermined position as the detected weak principal meridian direction. Pupil diameter detecting means for detecting the pupil diameter of the eye to be examined;
The eye according to any one of claims 1 to 5, wherein the control unit determines a moving amount for moving the measuring head from the predetermined position based on the detected pupil diameter. Refractometer.   The control means moves the measuring head from the predetermined position in a plane perpendicular to the optical axis of the measuring head when the measuring head is at a predetermined position. The eye refractive power measuring apparatus according to any one of 1 to 7. A measurement head having a low coherent light source that is a light source that projects index light onto the fundus of the eye to be examined, and an imaging unit that captures reflected and scattered light of the index light projected onto the fundus;
Drive means for moving the measurement head within a predetermined range in a plane perpendicular to the optical axis of the measurement head in a state where the measurement head is at a predetermined position with respect to the eye to be examined;
Calculating means for calculating an eye refractive power value of the eye to be examined based on an output of the imaging means obtained by imaging the reflected scattered light according to the movement of the measuring head;
An eye refractive power measuring device comprising: A measurement head having a low coherent light source that is a light source that projects index light onto the fundus of the eye to be examined, and an imaging unit that captures reflected and scattered light of the index light projected onto the fundus;
A driving means for driving the measuring head, and a control method for an eye refractive power measuring device comprising:
Controlling the driving means so that the measuring head is in a predetermined position with respect to the eye to be examined;
A step of calculating an eye refractive power value of the eye to be examined based on an output of the imaging means obtained by imaging the reflected scattered light while moving the measurement head from the predetermined position. A control method of the eye refractive power measurement device. Further comprising the step of generating a ring image based on the output of the imaging means obtained by imaging the reflected scattered light while moving the measuring head from the predetermined position;
The method for controlling an eye refractive power measurement apparatus according to claim 10, wherein, in the calculating step, an eye refractive power value of the eye to be examined is calculated based on the generated ring image.   In the generating step, a plurality of images are generated based on the output of the imaging means obtained by imaging the reflected scattered light while moving the measuring head from the predetermined position, and the plurality of generated The method of controlling an eye refractive power measurement apparatus according to claim 11, wherein the ring image is generated by performing an averaging process on images.   In the generating step, the ring image is generated based on an output of the imaging unit obtained by continuously storing the reflected scattered light in the imaging unit while moving the measuring head from the predetermined position. The method for controlling an eye refractive power measurement apparatus according to claim 11. The measurement head includes fixation means for presenting a fixation target to the eye to be examined to promote fixation,
Cloud means for moving the distance to present the fixation target to the eye to be examined in the distance, and further,
While driving the cloud means, the measuring head is held in a predetermined position.
The method for controlling an eye refractive power measurement apparatus according to claim 10, wherein, in the generating step, the ring image is generated after completion of the cloud fog. An astigmatism axis detecting step of detecting a weak principal meridian direction of astigmatism from the eye refractive power value based on the ring image;
The imaging means performs preliminary measurement of imaging the reflected scattered light when performing the cloud fog,
The method for controlling an eye refractive power measurement apparatus according to claim 14, wherein, in the controlling step, a direction in which the measuring head is moved from the predetermined position is the detected weak principal meridian direction. A pupil diameter detecting step of detecting a pupil diameter of the eye to be examined;
The amount of movement for moving the measuring head from the predetermined position is determined based on the detected pupil diameter in the controlling step. A method for controlling an eye refractive power measuring apparatus.   The measuring step includes moving the measuring head from the predetermined position in a plane perpendicular to the optical axis of the measuring head when the measuring head is at a predetermined position. Item 17. A method for controlling an eye refractive power measurement apparatus according to any one of Items 10 to 16. An eye refractive power measurement apparatus comprising: a measurement head having a low coherent light source that is a light source that projects index light onto the fundus of the eye to be examined; and an imaging unit that captures reflected and scattered light of the index light projected onto the fundus A control method,
Moving the measurement head within a predetermined range in a plane perpendicular to the optical axis of the measurement head in a state where the measurement head is at a predetermined position with respect to the eye to be examined;
An eye refractive power having a step of calculating an eye refractive power value of the eye to be examined based on an output of the imaging means obtained by imaging the reflected scattered light according to the movement of the measuring head. Control method of measuring device.   A program for causing a computer to execute each step of the control method according to any one of claims 10 to 18.