JP2005279305A - Ophthalmologic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily perform an alignment of a device with an eye to be examined. <P>SOLUTION: An ophthalmologic device for the alignment of a central axis of the device with the eye to be examined is equipped with a pair of illumination optical systems for illuminating an anterior ocular segment of the eye to be examined and forming a corneal reflected image of illumination at a position off the center of the corneal, a means for detecting positions of corneal reflected images of the illumination for detecting the positions of the corneal reflected images of the illumination by the illumination optical system, a control means for turning off a light source of an alignment index forming optical system in response to signals for starting a measurement and acquiring the positions of the corneal reflected images of the illumination immediately before starting the measurement and during the measurement by the means for detecting positions of corneal reflected images of the illumination, and a determining means for determining displacement during the measurement based on a change in the position of the corneal reflected image of the illumination during the measurement from the position of the corneal reflected image of the illumination immediately before starting the measurement. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an ophthalmologic apparatus used in an ophthalmic clinic or the like.

Conventionally, the alignment between the ophthalmologic apparatus and the eye of the subject is generally performed while observing the bright spot image and the aiming mark formed at the center of the cornea by the alignment light flux. Moreover, as alignment which does not utilize a cornea center luminescent point image, there exists what is performed by observing the Maying image and pupil shape formed in a cornea (refer patent document 1).
Japanese Patent Laid-Open No. 11-019040

However, the conventional apparatus has a problem that if the alignment light is turned off in order to prevent noise light during measurement, an alignment shift cannot be determined during measurement.
In view of the above prior art, it is an object of the present invention to provide an ophthalmologic apparatus that facilitates alignment of an apparatus with respect to an eye to be examined.

In order to solve the above problems, the present invention is characterized by having the following configuration.
(1) An alignment index forming optical system that projects an alignment beam toward the cornea to form an alignment cornea reflection image, an alignment index detection means that detects a two-dimensional position of the alignment cornea reflection image, A display means for observing the anterior ocular segment image of the optometry together with the aiming mark, and a pair of illumination optical systems for illuminating the anterior segment of the eye to be examined in an ophthalmic apparatus that aligns the central axis of the apparatus with the eye to be examined There is an illumination optical system that forms an illumination cornea reflection image at a position away from the center of the cornea, an illumination cornea reflection image position detection means that detects the position of the illumination cornea reflection image by the illumination optical system, and a response to the measurement start signal. Then, the light source of the alignment index forming optical system is turned off, and the illumination cornea reflection image position detection means obtains the position of the illumination cornea reflection image immediately before starting measurement and during measurement. Control means, and a judgment means for judging a displacement during measurement based on a change in the position of the illumination cornea reflection image being measured with respect to the position of the illumination cornea reflection image immediately before the start of measurement.

  According to the present invention, it becomes easy to align the apparatus with respect to the center of the cornea and the center of the pupil.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an external view of a hand-held type objective eye refractive power measurement apparatus according to the first embodiment, and FIG. 2 is a diagram showing an optical system arranged inside the apparatus.
A measurement window 4 is provided on the subject side of the apparatus 1, and a measurement light beam from the eye refractive power measurement optical system 20 is projected onto the subject eye along a reference optical axis passing through the center of the measurement window 4. Further, an anterior segment image of the eye to be examined is captured through the measurement window 4. Two anterior ocular segment illumination light sources 45 a and 45 b are arranged below the measurement window 4. An LCD monitor 5 and a switch unit 6 are disposed on the examiner side of the apparatus 1. The monitor 5 displays an anterior segment image, alignment information, and measurement information of the eye to be examined. An operator's grip 2 is provided below the device 1.

  In FIG. 2, the half mirror 10 is disposed on the optical axis L1 that is the central axis of the device facing the eye to be examined, and the eye refractive power measuring optical system 20 is disposed behind the half mirror. An infrared measurement light source 22, a rotating sector 23 having a slit aperture, a projection lens 25, and a limiting aperture 26 are arranged on the optical axis L2 side that is coaxial with the optical axis L1 by the half mirror 21 on the optical axis L1. The light source 22 is located at a position substantially conjugate with the vicinity of the eye cornea to be examined with respect to the projection lens 25. The rotating sector 23 is rotated in a certain direction by a motor 24. A plurality of slit openings in three meridian directions of 90 degrees, 30 degrees, and 150 degrees with respect to the rotation direction are formed on the side surface of the rotating sector 23.

The infrared light emitted from the light source 22 illuminates the slit opening of the rotating sector 23. The slit light beam scanned by the rotation of the rotating sector 23 is reflected by the beam splitter 21 after passing through the projection lens 25 and the limiting aperture 26. Thereafter, the light is transmitted through the beam splitter 10 and condensed near the cornea of the eye to be examined, and then projected onto the fundus.
On the optical axis L1, a light receiving lens 31, a diaphragm 32, and a light receiving portion 33 of a slit detection optical system are arranged. The diaphragm 32 is disposed at the focal position on the rear side of the light receiving lens 31, and the light receiving portion 33 is disposed at a position substantially conjugate with the eye cornea with respect to the light receiving lens 31. Three pairs of light receiving elements are provided on the light receiving section 33 every 60 degrees with the optical axis L1 as the center so as to correspond to the slit opening in the 3 meridian direction of the rotating sector 23.

The light beam of the slit image reflected by the fundus and passing through the pupil reaches the light receiving unit 33 via the light receiving lens 31, the diaphragm 32, and the like. The three pairs of light receiving elements on the light receiving unit 33 obtain phase difference signals corresponding to the scanning direction of the slit projection, respectively, and thereby the refractive power in the three meridian directions can be obtained, thereby measuring the refractive power of the eye to be examined. (Refer to Unexamined-Japanese-Patent No. 10-108836 about a refractive power measurement.).
On the optical axis L3 that is coaxial with the optical axis L1 by the half mirror, a visible light source 11, a fixation target 12, and lenses 13 and 14 constituting a fixation target optical system are arranged. 12 is integrally moved in the direction of the optical axis to cloud the eye to be examined. Further, a dichroic mirror 15 is disposed between the lens 14 and the half mirror 10, and has an imaging lens 16, a telecentric diaphragm 17, and an image sensor that constitute an observation optical system on the optical axis L4 in the reflection direction. A CCD camera 18 is arranged. This observation optical system also serves as an index detection optical system for detecting an alignment index.

  Further, an index projection optical system 40 that projects an alignment index for detecting a working distance direction that is also used for alignment in the vertical and horizontal (XY) directions is disposed around the optical axis of the optical axis L1. The index projection optical system 40 is symmetrical with two sets of first index projection optical systems 40a and 40b arranged symmetrically across the optical axis L1, and with the optical axis L1 sandwiched at a narrower angle than the first index projection optical system. Are provided with two sets of second index projection optical systems 40c and 40d, and the projection optical axes intersect at the same point on the optical axis L1. The first index projection optical systems 40a and 40b include light sources 41a and 41b that emit near-infrared light, spot stops 42a and 42b, and collimator lenses 43a and 43b, and project an index at infinity by a substantially parallel light flux. The second index projection optical systems 40c and 40d include light sources 41c and 41d that emit near-infrared light and spot stops 42c and 42d, and project a finite index onto the eye to be examined by divergent light flux. The alignment light projected by the index projection optical system 40 forms four index images (bright spot images) around the cornea outside the cornea center. The four sets of index projection optical systems are arranged in the horizontal direction in order to prevent the light flux from being lost due to eyelashes or eyelashes.

  In FIG. 2, 45a and 45b are anterior segment illumination light sources that emit near-infrared light, and the light sources 45a and 45b are at the same distance from the optical axis L1 so as to illuminate the eye to be examined obliquely from below. Arranged and in a predetermined positional relationship with the optical axis L1. The light sources 45a and 45b are finite distance light beams and form a bright spot image on the eye cornea to be examined.

  FIG. 3 is a diagram showing a main part of a control system block diagram of the apparatus. The output image from the CCD camera 18 is subjected to predetermined processing and is taken into the image memory 51. An image from the CCD camera 18 is displayed on the monitor 5 via the image composition unit 52. 53 is a character generating unit that generates various characters and characters to be displayed on the monitor 5. The signal of the character generating unit 53 is electrically combined with the video signal from the CCD camera 18 by the image combining unit 52, and the monitor 5. Displayed above. An image processing unit 55 detects a signal from an image captured in the frame memory, and the calculation / control unit 50 obtains the position of the index image based on the signal detected by the image processing unit 55 and controls the character generation unit 53. Output a signal. The calculation / control unit 50 is connected to each light source, a light receiving unit 33 for measuring eye refractive power, a fixation target moving unit 57, and the like, and controls eye refractive power measurement and calculates refractive power.

The operation of the above configuration will be described.
When the anterior segment illumination light sources 45a and 45b and the alignment index projection light sources 41a to 41d are turned on and the measurement window 4 is positioned so as to face the eye to be examined, the corneal reflection luminescent spot image and the anterior segment image are displayed on the CCD. The image is captured by the camera 18 and displayed on the monitor 5. In the screen on the monitor 5 shown in FIG. 3, 41a ′ and 41b ′ indicate bright spot images by the first index projection optical systems 40a and 40b, and 41c ′ and 41d ′ indicate brightness by the second index projection optical systems 40c and 40d. A point image is shown. 45a 'and 45b' indicate bright spot images by the anterior segment illumination light sources 45a and 45b.

  The image captured in the image memory 51 is processed by the image processing unit 55, and each bright spot image signal is input to the calculation / control unit 50. The calculation / control unit 50 obtains the XY coordinates of each bright spot image from the input signal, and detects the center of the XY coordinates of the bright spot images 41a ′ and 41b ′ formed by the light beam at infinity as the cornea center. If four bright spot images arranged in the same line in the X direction are detected, the bright spot images 41a ′ and 41b ′ are formed by the first index projection optical systems 40a and 40b on the both ends from the positional relationship. Can be determined. When the corneal center coordinates are obtained, the calculation / control unit 50 forms an alignment cross mark 100 at a position on the monitor 5 corresponding to the center coordinates. The cross mark 100 is generated by the character generating unit 53, and the signal is electrically combined with the image signal from the CCD camera 18 by the image combining unit 52 and displayed on the monitor 5. When the apparatus 1 is moved in the X and Y directions, the coordinate positions of the bright spot images 41a ′ and 41b ′ change accordingly. Therefore, the cross mark 100 is always at the center of the bright spot images 41a ′ and 41b ′, that is, on the monitor 5. The image is moved and displayed so as to be approximately at the center of the cornea in the anterior segment image.

  Further, a square aiming marker 101 generated by the character generation unit 53 is electrically synthesized by the image synthesis circuit 52 and displayed at a predetermined position on the monitor 5. The center of the aiming marker 101 is set as the alignment center in the X and Y directions, and the examiner aligns the cross mark 100 at the center of the aiming marker 101, that is, by observing and aligning the conventional corneal center bright spot image. Similarly, alignment in the XY directions is performed by moving the apparatus 1 with respect to the eye to be examined.

  The center of the XY coordinates of the bright spot images 41c ′ and 41d ′ may be substantially the corneal center. However, a finite distance light beam tends to be inaccurate when the deviation of the corneal center from the optical axis L1 is large. It is preferable to use the bright spot images 41a ′ and 41b ′ formed by the light beam. When an infinite light beam is used, it is almost the same as in the case where a light beam is projected from the conventional optical axis L1 to create a bright spot, and it is easy to perform alignment while observing the anterior segment on the monitor 5.

  The detection of the alignment state in the Z direction (working distance direction) is performed by comparing the interval between the bright spot images 41a ′ and 41b ′ and the gap between the bright spot images 41c ′ and 41d ′. This is because when the corneal reflection image is formed by infinite light and finite light, the height of the corneal reflection image by infinite light does not change even if the working distance changes, but the corneal reflection image by finite light This utilizes the characteristic that the image height changes. Using this relationship, the amount of deviation with respect to the appropriate working distance and its direction are detected from the coordinate positions of the bright spot images 41a ′, 41b ′, 41c ′, and 41d ′. For details, refer to Japanese Patent Laid-Open No. 6-46999 filed by the present applicant.

  The calculation / control unit 50 causes the monitor 5 to display an indicator for guiding the moving direction via the character generation unit 53 based on the detection information of the alignment state in the Z direction. FIG. 4 shows an example thereof (illustration of each bright spot image is omitted), and focus bars 105 are displayed on both the left and right sides of the aiming marker 101. When the focus bar 105 extends downward on the screen, it indicates that the apparatus is closer to the proper working distance. When the focus bar 105 extends upward, the apparatus is less than the proper working distance. Indicates that the subject is on the eye side. When there is only one focus bar 105, it indicates that the proper working distance is within the allowable range.

  When the apparatus 1 is moved and the state in each direction of XYZ falls within a predetermined allowable range, the measurement light source 22 is turned on under the control of the calculation / control unit 50, and the eye refractive power measurement is automatically executed. The eye refractive power is measured by preliminary measurement based on new phase difference signals from the three pairs of light receiving elements on the light receiving unit 33, and the fixation target 12 is moved based on this result by an amount corresponding to the diopter appropriate for the eye to be examined. Perform the measurement with cloud fog. During the measurement of the eye refractive power, if the corneal reflection light of the alignment light is incident on the light receiving element of the light receiving unit 33, the measurement accuracy is easily affected. For this reason, the light sources 41a to 41d for alignment are turned off during measurement.

  If the light sources 41a to 41d are turned off during the measurement, alignment information based on the bright spot image of the index projection optical system 40 cannot be obtained, and the alignment marks cannot be displayed. For this reason, it is impossible to find an accuracy defect due to misalignment during measurement. As this correspondence, the bright spot images 45a ′ and 45b ′ by the anterior segment illumination light sources 45a and 45b are used. The anterior segment illumination light sources 45a and 45b are always lit for anterior segment observation and are located away from the measurement optical axis, so that the alignment light sources 41a to 41d are turned on. Has little effect on measurement.

  The calculation / control unit 50 responds to the measurement start signal and the positional relationship between the central coordinates of the bright spot images 41a ′ and 41b ′ (detected coordinates of the cornea center) and the coordinates of the bright spot images 45a ′ and 45b ′ immediately before the start of measurement. Is temporarily stored. During the measurement, displacement information about the cornea center is obtained from the change in the position of the bright spot images 45a ′ and 45b ′, and the displacement in the Z direction is obtained from the image interval between the bright spot images 45a ′ and 45b ′. In this way, it is possible to determine the misalignment during measurement without being affected by the corneal curvature. The calculation / control unit 50 moves the display of the cross mark 100 according to the displacement information of the cornea center, and changes the display of the focus bar 105 according to the displacement information in the Z direction. As a result, the examiner can know the misalignment during the measurement on the monitor 5. The calculation / control unit 50 determines a measurement error when the coordinate positions of the bright spot images 45a ′ and 45b ′ stored immediately before the start of measurement change beyond the allowable range.

  In the above description, the alignment index for detecting the corneal center is a bright spot, but this may be an annular index (Mearing), and the annular index is also arranged symmetrically with respect to the optical axis L1. It can be handled that a large number of bright spots are formed by the optical system. When an annular index is projected onto the eye cornea to be examined, the center thereof is substantially the center of the cornea. The center of the annular index image is detected by the image processing unit 55, and the cross mark 100 is displayed on the monitor 5 in accordance with the coordinate position thereof, so that even in the case of an annular index image, center alignment can be easily performed. become.

Next, a second embodiment will be described. Since the components themselves of the second embodiment are the same as those of the apparatus of the first embodiment, the same reference numerals are used to focus on the operations of different parts.
In the second embodiment, the measurement light source 22 is turned on also during alignment so that it is shared as an alignment light source, and a light beam is projected from the direction of the optical axis L1 to form a corneal center bright spot image. In this case, it is not necessary to provide a light projection optical system for forming a corneal center bright spot image, so that the configuration of the apparatus can be simplified. However, the luminous flux of the eye refractive power is generally narrowed in order to increase the measurement accuracy, and the corneal center bright spot image is not obtained unless the measurement optical axis (L1) is aligned to the vicinity of the cornea center. Does not appear. This makes it difficult to know the direction in which the device should be moved until the corneal center bright spot image appears, which is inconvenient.

  Therefore, in the second embodiment, until the corneal central luminescent spot image can be observed on the monitor 5, the brightness projected on the periphery of the cornea by the first index projection optical systems 40a and 40b is the same as in the previous embodiment. The cross mark 100 is electrically combined and displayed on the monitor 5 using the point images 41a ′ and 41b ′. Then, as shown in FIG. 5, when the corneal center bright spot image 110 by the measurement light source 22 appears, the cross mark 100 is not displayed. The image captured by the CCD camera 18 is processed by the image processing unit 55, and the position coordinates of the bright spot images 41a ′, 41b ′, 41c ′, 41d ′ around the cornea and the central bright spot image 110 of the cornea are calculated and controlled. 50 is obtained. The central corneal bright spot image 110 can be identified as the center from the positional relationship of the five bright spot images. The calculation / control unit 50 determines whether or not the cornea center luminescent spot image 110 captured by the CCD camera 18 has a visible sensitivity that can be observed on the monitor 5 (this is determined from the detected light amount). If possible, the control signal of the cross mark 100 is sent to the character generation unit 53 to turn off the display (the cross mark 100 is switched to non-display).

  The reason why the cross mark 100 is erased when the optically formed bright spot image 110 can be observed is as follows. Since the cross mark 100 is displayed based on the result of detecting the bright spot image around the cornea, there is a slight time lag in movement. Further, there may be a deviation from the optically formed bright spot image 110 due to the detection accuracy of the bright spot image. For this reason, if there is a cross mark 100 indicating a pseudo substantially corneal center in addition to the actual bright spot image 110, conversely, it becomes confusing when aiming.

Therefore, the examiner performs alignment according to the cross mark 100 until the corneal center luminescent spot image 110 appears on the monitor 5, and when the corneal center luminescent spot image 110 appears, aligns it so as to be positioned at the center of the aiming marker 101. When the alignment is shifted and the corneal center bright spot image 110 cannot be detected, the calculation / control unit 50 displays the cross mark 100 again.
In the above description, the cross mark 100 is erased when the bright spot image 110 can be observed. However, since the fine alignment is near the center of the aim, the bright spot image 110 is within a predetermined range within the aiming marker 101 or the like. When entering, the cross mark 100 may be erased.

  Even in an optical system in which the width of the alignment light beam forming the corneal center luminescent spot image 110 is wide, if the cross mark 100 is displayed according to the visible state of the corneal center luminescent spot image 110, the usability is improved. That is, when the working distance or the like is large and the corneal center bright spot image is blurred, alignment can be performed according to the display of the cross mark 100. Also in this case, if the sensitivity is such that the corneal center luminescent spot image can be clearly recognized, the cross mark 100 is not displayed, and the examiner may perform alignment according to the corneal center luminescent spot image.

A third embodiment will be described. The third embodiment is an example of alignment with the center of the pupil, and the constituent elements are the same as those in the first embodiment, so that the same reference numerals are used for the description.
The anterior ocular segment image captured by the CCD camera 18 is processed by the image processing unit 55 to detect the pupil edge. In the anterior segment image, the brightness varies depending on the pupil, iris, and sclera, so the pupil edge coordinates can be detected from this information, and the center position coordinates, that is, the coordinates of the pupil center position can be detected from the pupil edge detection. Is required. On the monitor 5, as shown in FIG. 6, a cross mark 100 ′ substantially indicating the center of the pupil is electrically combined and displayed by the character generation unit 53 that receives a control signal from the calculation / control unit 50. The examiner performs centering alignment by moving the apparatus 1 so that the cross mark 100 ′ is positioned at the center of the aiming marker 101. The alignment in the working distance direction is the same as in the first embodiment. The bright spot images by the first index projection optical systems 40a and 40b and the second index projection optical systems 40c and 40d (not shown in FIG. 6). Can be used.
In the eye refractive power measurement, a measurement light beam is projected into the eye through the pupil. When the center of the cornea and the center of the pupil are deviated, the measurement light beam is focused on the iris in the alignment based on the center of the cornea, and measurement is impossible. In such a case, measurement can be performed by performing alignment based on the pupil center.

A fourth embodiment will be described. In the fourth embodiment, as shown in FIG. 7, a display 220 such as a transparent LCD panel is inserted in the observation optical path of the optical observation system 200, and an alignment mark to be electrically formed is displayed on the display 220. Combine with the anterior segment image.
FIG. 7 shows a corneal surgery apparatus (see Japanese Patent Laid-Open No. 6-114083) that corrects refractive errors by irradiating the cornea with excimer laser light to change the corneal curvature. In this ophthalmic apparatus, a laser is used. An operation is performed by aligning the irradiation optical axis L and the center of the pupil. The excimer laser light is reflected by the dichroic mirror 201 and applied to the patient's eye (examined eye) cornea. The observation optical system 200 has an objective lens 202, a declination prism 203, and an eyepiece lens 204, and the operator's eye observes the anterior eye portion of the eye to be examined illuminated by the illumination light source 207.

Further, the anterior segment of the eye to be examined is imaged by a CCD camera 212 having an imaging device via a beam splitter 210 and an imaging lens 211, and an output signal thereof is connected to an image processing unit 215. The image processing unit 215 performs pupil center detection, and the control unit 216 displays the cross mark 100 ′ as shown in FIG. 6 and controls the display position based on the detection result of the pupil center. To do. The aiming marker 101 is displayed at a predetermined position on the display 220. The surgeon moves and aligns the apparatus so that the cross mark 100 ′ indicating the approximate pupil center is positioned at the center of the aiming marker 101.
It should be noted that the method of combining and displaying alignment marks in such an optical observation system can be similarly applied to the devices of the first to third embodiments.

It is a figure which shows the external appearance of the objective type | formula eye refractive power measuring apparatus of embodiment. It is a figure which shows the optical system arrange | positioned inside the apparatus of embodiment. It is a figure which shows the principal part of the control system block diagram of an apparatus. It is a figure explaining the indicator for guiding the movement of a Z direction. It is a figure which shows the example of a screen when the cornea center luminescent spot image in 2nd Embodiment appears. It is a figure which shows the example of a screen by which the cross mark which shows the approximate pupil center in 3rd Embodiment was synthesize | combined and displayed. It is a figure which shows the structure of the ophthalmologic apparatus of 4th Embodiment.

Explanation of symbols

5 monitor 18 CCD camera 20 eye refractive power measurement optical system 40a, 40b first index projection optical system 40c, 40d second index projection optical system 45a, 45b anterior segment illumination light source 50 calculation / control unit 52 image synthesis unit 53 character generation 55 Image processor 100 Cross mark

Claims (1)

An alignment index forming optical system for projecting an alignment light beam toward the cornea to form an alignment cornea reflection image, an alignment index detection means for detecting a two-dimensional position of the alignment cornea reflection image, and a front of the eye to be inspected A pair of illumination optical systems that illuminate the anterior segment of the eye to be examined in an ophthalmic apparatus that aligns the central axis of the apparatus with the eye to be examined. In response to a measurement start signal, an illumination optical system that forms an illumination corneal reflection image at a position away from the center, an illumination corneal reflection image position detection unit that detects the position of the illumination corneal reflection image by the illumination optical system, Control to turn off the light source of the alignment index forming optical system and obtain the position of the illumination corneal reflection image immediately before the start of measurement and during the measurement by the illumination corneal reflection image position detection means Ophthalmologic apparatus characterized by comprising: a stage, a determination means for determining the positional deviation in the measurement based on the change in position of the illumination cornea reflection image in the measurement with respect to the position of the illumination cornea reflection image of the measurement immediately before the start.