JP3979877B2 - Ophthalmic examination equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ophthalmic examination apparatus provided with a mechanism for aligning the optical axis or magnification of an eye to be examined and an optical system.
[0002]
[Prior art]
In an ophthalmic examination apparatus such as a fundus camera, an alignment (positioning) operation is performed before photographing (or observation). This alignment operation is performed based on the observation image of the anterior segment of the eye to be examined. The main purpose of this alignment is to make the optical axes of the eye to be examined and the fundus camera coincide with each other. At this time, it is advantageous if the mydriatic state can be confirmed to be sufficient for photographing (or observation). .
[0003]
In the fundus camera, in order to confirm the mydriatic state of the eye to be examined at the time of alignment, conventionally, (1) the pupil diameter of the eye to be examined is measured and the measurement result is displayed or a warning is given based on the measurement result (2 A technique has been proposed in which a mark corresponding to the minimum pupil diameter is generated so that the examiner can visually recognize it on the observation screen, and the mydriatic state of the eye to be examined is confirmed by comparing the mark with the pupil diameter.
[0004]
[Problems to be solved by the invention]
Among the above, various conventional techniques (1) for measuring the pupil diameter in a fundus camera have been proposed, but many of them require a complicated process of measuring the distance to the eye to be examined, and the configuration of the apparatus is large. There are problems that tend to be complex and expensive.
[0005]
Of the above, the prior art (2) using the mark corresponding to the minimum pupil diameter corresponds to the minimum pupil diameter based on the imaging magnification of the main optical system when the fundus camera body is positioned at a predetermined initial position, for example. Since the mark of a size to be displayed is displayed in the observation image by electronic or optical means, there is a problem that the mydriatic state of the eye to be examined cannot be accurately determined.
[0006]
For example, it is conceivable that the initial position of the fundus camera body at the start of alignment using a mark corresponding to the minimum pupil diameter is determined based on the chin rest on which the subject places his chin, but the position of the human anterior eye portion is Measured with the jaw position as the reference, there is an individual difference of about 20 mm at the maximum in the front-back (optical axis) direction. The initial position determined with reference to the position of the jaw table is already about 1.5 times on the observation screen. That is, the difference in magnification is produced.
[0007]
In other words, simply displaying the mark corresponding to the minimum pupil diameter, assuming the imaging magnification at the initial alignment position, does not necessarily match the actual imaging magnification. Absent. For example, even if a mark corresponding to a minimum pupil diameter of 4 mm is generated, the mark on the screen actually does not exactly match the 4 mm, and has a size in the range of about 3 mm to 6 mm. There are many cases.
[0008]
One method for solving this problem is to accurately determine the actual imaging magnification and determine the display size of the mark based on the actual imaging magnification. However, in order to actually measure the imaging magnification, the distance from the eye to be examined, Alternatively, a process of actually measuring the imaging magnification is necessary, and there is a problem that the configuration of the apparatus tends to be complicated and expensive as in the above-described conventional technique (1).
[0009]
SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described problems, to easily perform an accurate alignment operation in an ophthalmic examination apparatus such as a fundus camera, and to check the mydriatic state of the eye to be examined with a simple and inexpensive configuration. It is in.
[0010]
[Means for Solving the Problems]
In order to solve the above problems, according to the present invention, an optical system for acquiring an anterior ocular segment observation image of an eye to be examined, and an iris outer diameter of the eye to be examined in the anterior ocular segment observation image obtained by the optical system Means for generating a first mark for positioning in the anterior ocular segment observation image, and the examiner adjusts the positional relationship between the optical system and the eye to be examined, and A configuration that achieves optical axis alignment and magnification alignment between the eye to be examined and the optical system by aligning the iris outer diameter of the eye to be examined in the eye observation image, or, further, to the eye to be examined When the optical axis alignment and magnification alignment of the optical system are achieved, the examiner displays the second mark having a size corresponding to the minimum pupil diameter necessary for photographing the eye to be examined by the optical system. In the anterior eye observation image so that it can be compared with the pupil size of the subject's eye Configured to be generated employing a (claim 2).
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows the structure of an ophthalmic examination apparatus employing the present invention.
[0012]
First, the optical system of the apparatus will be described. In the apparatus of FIG. 1, an observation light source 2 such as a halogen lamp is disposed at the center of a mirror 1, and light emitted from the light source 2 passes through a condenser lens 3, a filter 4, a mirror 5, a lens 6, and a ring. Is incident on a ring slit 7 for forming a shaped illumination. The ring slit 7 can be replaced with another ring slit 7a for the purpose of adjusting the amount of illumination light. Which ring slit is used is controlled by the control unit 41 described later.
[0013]
The filter 4 is an infrared filter that transmits only infrared light, and the mirror 5 is composed of either a half mirror, a dichroic mirror (visible light transmission, infrared light reflection), or a return mirror (a mirror that can be inserted and removed). The
[0014]
The light beam that has passed through the ring slit 7 (or 7a) then passes through the relay lens 8 and is conjugated with the anterior segment of the eye to be examined through the black spot plate 9, the return mirror M1, and the lens 10 for reflecting the objective lens. After being reflected by the perforated total reflection mirror 11 disposed at the position, the light passes through the objective lens 12 and enters the fundus Er from the pupil (iris) Ep of the eye E to be examined.
[0015]
The reflected light from the fundus Er is again received from the pupil Ep through the objective lens 12, passes through the focusing lens 16 and the imaging lens 17 through the hole of the perforated total reflection mirror 11, and enters the return mirror 18. .
[0016]
A photographing aperture 11 a is disposed at the rear of the perforated total reflection mirror 11. The aperture value of the photographing aperture 11a is controlled by the control unit 41 described later.
[0017]
The light reflected by the return mirror 18 passes through a field stop (mask) 19 placed at the focus position, and then forms an image on an image pickup device 23 such as a CCD via a field lens 20, a mirror 21, and a lens 22. The image captured by the element 23 is displayed on the monitor M through the image processing of the image processing unit 42 and observed by the examiner.
[0018]
If the fundus image is to be photographed on the photographing medium 24 (film or the like), when the strobe 14 placed at the center of the mirror 13 is caused to emit light, the fundus Er is formed through the condenser lens 15 and the mirror 5 through the same route as described above. Illuminated, and in synchronization with this, the return mirror 18 is removed from the optical path, and a fundus image is photographed on the photographing medium 24. The amount of light of the strobe 14 is controlled by a control unit 41 described later.
[0019]
The imaging medium 24 can be composed of not only a film but also an imaging element such as a CCD. In this case, the gain of the captured image signal can be adjusted by the control unit 41 described later.
[0020]
An anterior lens observation auxiliary lens (hereinafter referred to as an anterior eye lens) L1 is disposed between the perforated total reflection mirror 11 and the objective lens 12 so that it can be inserted into or removed from the optical path.
[0021]
The anterior eye lens L1 is inserted at the time of alignment, and in this state, the examiner moves the position of the main body 101 with an operating means (not shown) while observing the anterior eye image with the imaging device 23 to the monitor M of the anterior eye part. The main body 101 and the eye E are aligned by adjusting the position of the eyepiece E. When shifting to photographing, the lens power of each optical element of the anterior eye lens L1 and the main optical system is selected so that a magnification and a field of view suitable for fundus photographing can be obtained by removing the anterior eye lens L1 from the main optical system. Is done.
[0022]
A return mirror M1 is arranged between the relay lens 8 and the lens 10, and a light source 30 for projecting an alignment index through the return mirror M1 and an alignment index 31 including a pinhole are provided. .
[0023]
The position of the index 31 is set so as to form an image on the anterior eye portion of the eye to be examined, that is, the pupil (iris) Ep of the eye to be examined via the anterior eye lens L1 when the alignment of the eye to be examined and the apparatus is correct. The That is, when the anterior segment lens L1 is inserted, the anterior segment of the eye to be examined becomes conjugate with the observation image plane (imaging device 23) instead of the fundus, and the alignment index imaged on the pupil (iris) Ep of the examined eye. The imaging state can be observed. At the time of alignment, the examiner can confirm the alignment state by using the mark 51 described later and further using the position of the image of the index 31 in the observation image.
[0024]
The optical system is housed in the main body 101, and the objective lens 12 is disposed on the front side with respect to the eye E and the monitor M is disposed on the back side with respect to the examiner. The main body 101 can be moved on a gantry via an operating means (not shown), whereby an alignment operation with the eye E is performed.
[0025]
In FIG. 1, reference numeral 41 denotes a control unit including a microprocessor and a ROM storing a control program thereof, a RAM used as a work area and an image memory, and the like. The control unit 41 controls the operation of the entire fundus camera including the structural members that have been explicitly described above, as well as the structural members that have not been explicitly described above.
[0026]
In this embodiment, during alignment, when an image captured by the image sensor 23 is displayed on the monitor M, a mark as shown on the right side of FIG.
[0027]
Reference numeral 50 denotes a display screen of the monitor M, reference numeral 51 denotes a first mark for aligning / magnifying (size) with the iris outer diameter of the eye E, and reference numeral 52 denotes the mark 51 and iris outer diameter. This is a second mark for indicating the minimum pupil diameter in the state where the position / magnification matching is performed.
[0028]
The present invention utilizes the fact that the size of the outer diameter of a human iris is about 11 ± 1 mm for a general adult and the individual difference is relatively small, and arc-shaped marks 51 and 51 (two on the left and right in the present embodiment). When the desired imaging magnification is obtained with respect to the image sensor 23, the image is displayed on the screen of the monitor M so as to correspond to the size of the iris outer diameter (for example, 11 mm).
[0029]
If the display sizes of the marks 51 and 51 are determined in this manner, the arc-shaped mark 51 superimposed on the observation image of the monitor M matches the iris outer diameter of the eye E (see FIG. 2). In this way, if the main body 101 is operated for positioning, the desired imaging magnification can be obtained.
[0030]
On the other hand, the second mark 52 is constituted by a dot display arranged so as to have an inner diameter corresponding to a minimum pupil diameter (for example, 4 mm) determined according to necessary imaging conditions at the above-described desired imaging magnification. ing.
[0031]
The first and second marks 51 and 52 are arranged at positions based on the center of the anterior ocular segment observation screen.
[0032]
Therefore, when the main optical system is positioned by operating the main body 101 so as to match the iris outer diameter of the eye E to be examined, the examiner displays the mark 52 on the anterior ocular segment observation image displayed on the monitor M. By comparing the pupil diameters, it can be determined whether or not a mydriatic state in which the pupil diameter is equal to or greater than the minimum pupil diameter is obtained.
[0033]
The determination of the mydriatic state can be performed not only by the examiner but also by calculation of the control unit 41. The control unit 41 performs image recognition processing on the anterior ocular segment observation image data obtained from the image sensor 23 (which may be a single still image data obtained at a certain timing), thereby producing a pupil outline (of the pupil and iris). The boundary: reference numeral 54) in FIG. 2 can be detected, and the size (pupil diameter) can be calculated.
[0034]
The recognition of the outline of the pupil and the calculation processing of the pupil diameter are executed in a state where the body 51 is operated and positioned so that the mark 51 matches the iris outer diameter of the eye E as described above. This can be done with extremely low calculation costs. This is because in the state where the mark 51 matches the iris outer diameter of the eye E, the optical axes of the main optical system and the eye E match and the desired imaging magnification is formed.
[0035]
That is, when the optical axes of the main optical system and the eye E to be examined are coincident with each other, it is clear that the outline of the pupil exists concentrically from the center of the image. The contour of the pupil can be easily detected by detecting the concentration (luminance) difference existing concentrically.
[0036]
Also, since the desired imaging magnification is obtained, the size of the detected pupil contour, that is, the actual pupil diameter, can be easily calculated based on the imaging magnification.
[0037]
Therefore, a specific switch that indicates a specific timing at which the user has determined that the mark 51 has been operated and positioned so that the mark 51 matches the iris outer diameter of the eye E to be examined, for example, “end alignment”, If a switch with a name such as “Determination of Pupil Diameter” is provided, and the operation of this switch is detected, then the pupil diameter is recognized and the pupil diameter calculation process is performed, so that the pupil diameter can be measured easily and reliably. be able to.
[0038]
The pupil diameter measured in this manner can be displayed numerically (for example, in mm) on the monitor M, and a warning can be displayed on a screen as shown in FIG.
[0039]
FIG. 2 shows a display example of the monitor M, and shows three display examples M1 to M3 of “good mydriasis”, “little mydriatic”, and “short mydriatic”.
[0040]
In FIG. 2, reference numerals I <b> 1 to I <b> 3 indicate an anterior ocular segment observation image region that displays a (still) image used for the above-described pupil diameter measurement process or a real-time moving image obtained by the image sensor 23. On the anterior ocular segment observation image regions I1 to I3, the above-described first marks 51 and 51 and the second mark 52 are superimposed and displayed.
[0041]
The display states of the anterior ocular segment observation image regions I1 to I3 in FIG. 2 are all after the alignment operation described above, and the first marks 51 and 51 coincide with the outer diameter 53 of the iris of the eye E to be examined. Yes. The diameter of the second mark 52 matches the required minimum pupil diameter (for example, 11 mm) as described above.
[0042]
In the display example M1 of FIG. 2, the pupil contour 54 is larger than the diameter of the mark 52, and naturally, the above-described measurement result of the pupil diameter is a value larger than the minimum pupil diameter of the mark 52. In this detection state, the control unit 41 displays messages such as “mydriatic state is good” and “capable of photographing with 0 flash light” on the monitor M as indicated by reference numerals m11 and m12. Inform the examiner of the condition.
[0043]
In the display example M2, the pupil contour 54 is slightly smaller than the diameter of the mark 52, and the measurement result of the pupil diameter is accordingly smaller than the minimum pupil diameter of the mark 52. In this detection state, the control unit 41, as indicated by reference numerals m21 and m22, “the mydriatic is inadequate”, “shoot with the flash light amount set to +1 or +2” (the light amount of the strobe 14 can be adjusted manually. In such a case, a message display like the above is performed on the monitor M to notify the examiner of the mydriatic state and warn that it is necessary to increase the light amount of the strobe 14.
[0044]
In the display example M3, the pupil contour 54 is considerably smaller than the diameter of the mark 52, and the measurement result of the pupil diameter is a value smaller than the minimum pupil diameter of the mark 52. In such a detection state, the control unit 41 displays a message display such as “My pupil is insufficient” or “My pupil is insufficient. Photographs with uniform light cannot be taken” as indicated by symbols m31 and m32. The warning is made that shooting is not possible.
[0045]
Further, numerical displays (for example, in mm) such as the actually measured pupil diameter, the iris outer diameter size corresponding to the mark 51, and the minimum pupil diameter size corresponding to the mark 52 may be added to the display examples M1 to M3.
[0046]
By performing the display as shown in FIG. 2, the examiner can obtain detailed information on the mydriatic state at the stage where the anterior segment alignment is completed, and determines whether or not imaging can be performed reliably. It is possible to appropriately select measures such as taking necessary measures such as correcting the amount of strobe light, adding a mydriatic agent, or giving up photographing.
[0047]
In the above, an example in which the actually measured pupil diameter is displayed with numerical values and characters has been described. However, the actually measured pupil diameter can also be used for controlling the operation of the fundus camera. Control of the operation of the fundus camera includes not only a mode for prohibiting / permitting shooting but also a mode for automatically controlling shooting conditions.
[0048]
For example, when prohibiting / permitting photographing based on the measured pupil diameter, the control unit 41 compares the measured pupil diameter with the required minimum pupil diameter, and if the difference is greater than or equal to a predetermined value, the display example M3 in FIG. And an operation of a shutter button (not shown) (or an operation for entering another photographing mode) is invalidated.
[0049]
When the imaging condition is automatically controlled based on the actually measured pupil diameter, the control unit 41 uses the imaging condition related to the image brightness (exposure) based on the actually measured pupil diameter, for example, the light amount of the strobe 14 ( The gain of the imaging medium 24 (by a CCD or the like), the aperture value of the aperture 11a, the ring slit 7 (7a), etc. are selected. Of course, here, the above-mentioned various photographing conditions are automatically controlled to correct the direction in which the illumination light quantity is increased as the actually measured pupil diameter is smaller.
[0050]
In addition, a configuration in which the control unit 41 automatically controls post-processing (for example, adjustment of the angle of view) of the image captured by the imaging medium 24 based on the actually measured pupil diameter is also conceivable. As post-processing of the captured image, for example, automatic trimming of image data in which a peripheral area where the image quality of the photographed fundus image is deteriorated is electronically removed or masked with black data is known. If the pupil diameter is small, the peripheral area where the image quality deteriorates becomes large. Therefore, it is sufficient to perform control to enlarge the area to be removed or masked by trimming.
[0051]
As described above, this embodiment pays attention to the fact that there is relatively little individual difference in the size of the human iris outer diameter, and the iris outer diameter and position (optical axis) alignment / magnification (size) alignment of the eye E to be examined are performed. A first mark 51 to be generated is generated in the anterior ocular segment observation image, or a second mark 52 to indicate the minimum pupil diameter in a state where the position / magnification of the mark 51 and the iris outer diameter is adjusted. Are generated in the anterior ocular segment observation image at a fixed size.
[0052]
By using such a mark 51, the position / magnification of the eye to be examined and the fundus camera can be adjusted easily and accurately, and the mark 52 is used when the position / magnification of the eye to be examined and the fundus camera has been adjusted. The examiner can easily determine whether or not the mydriatic state is sufficient.
[0053]
Further, in the state where the position / magnification of the eye to be examined and the fundus camera has been adjusted by the mark 51, the pupil contour and the pupil diameter can be actually measured based on the anterior ocular segment image data at a very low calculation cost. Based on the measured pupil diameter, the operation of the fundus camera can be controlled.
[0054]
Now, after the alignment using the anterior segment image is completed, the fundus photographing mode is entered. At this time, the anterior segment lens L1 is removed from the optical path of the main optical system, and the main optical system is focused on the fundus. To be adjusted. A configuration in which the anterior eye lens L1 is not used is also conceivable, but in that case, the main body 101 is advanced in the direction of the eye E to be adjusted so that the main optical system is focused on the fundus.
[0055]
After the alignment is completed, the fundus photographing mode is entered. In the fundus photographing mode, the first and second marks 51 and 52 are no longer necessary, and are preferably deleted so that they are not displayed on the observation image. . The erasing of the first and second marks 51 and 52 is an operation for shifting to the fundus photographing mode, for example, removal of the anterior eye lens L1 or advancement of the main body 101 is detected by a limit switch and the fundus photographing mode. It may be performed at the time when the shift operation is detected. However, it is also possible to use a configuration in which the display and deletion of the first and second marks 51 and 52 are all controlled by the examiner's manual operation.
[0056]
In the above, an example has been shown in which the iris outer diameter is focused on as a part where the individual difference of the eye to be examined is relatively small, and the mark 51 for performing position / magnification matching with this is generated. It may be for adjusting the position / magnification with a few eye regions to be examined.
[0057]
In the above description, the marks 51 and 51 are composed of two arcs divided into right and left as shown in FIGS. 1 and 2, and the mark 52 is composed of a plurality of dot displays arranged in a circle. The shape of the mark is arbitrary, and may be any shape as long as the examiner can perform the above-described position / magnification adjustment and pupil diameter determination. For example, the marks 51 and 52 can both be a continuous annular display or the like, and the display color of these marks is arbitrary as long as it is easy for the examiner to visually recognize. However, in the configuration in which the mark 51 is displayed as two arcs divided into left and right as shown in FIGS. 1 and 2, the position / magnification can be reliably aligned with the left and right edges of the iris that are hardly hidden by the eyelids or the like. There is a merit that.
[0058]
Note that the minimum pupil diameter corresponding to the mark 52 may change depending on the imaging mode such as the infrared imaging mode or the fluorescence mode, and the light emission power when the strobe 14 is replaceable. Therefore, it goes without saying that the display size of the mark 52 may be appropriately controlled according to the minimum pupil diameter determined according to the operation mode of the apparatus, the light emission power of the strobe 14, and various other operation conditions of the apparatus.
[0059]
In the above description, the marks 51 and 52 are generated by electronically superimposing and displaying on the anterior segment image, but may be generated optically. For example, by using a mechanism similar to the bright frame display mechanism of the range finder camera, marks 51 and 52 having an appropriate shape can be generated on the conjugate plane of the anterior segment.
[0060]
The present invention is not limited to the product category such as “fundus camera”, and it is necessary to align the apparatus and the eye to be examined using the anterior eye image and to evaluate the mydriatic state of the eye to be examined. Needless to say, any ophthalmic examination apparatus can be applied to any ophthalmic examination apparatus.
[0061]
【The invention's effect】
As is apparent from the above description, according to the present invention, an optical system for acquiring an anterior ocular segment observation image of the eye to be examined, and an extra-iris of the eye to be examined in the anterior ocular segment observation image obtained by the optical system are described. and means for generating in the anterior ocular segment observation image of the first mark for aligning diameter and position, the examiner adjusts the positional relationship between the optical system and the eye to be examined, the said first mark A configuration in which alignment of the optical axis and magnification of the subject eye and the optical system is achieved by aligning the iris outer diameter of the subject eye in the anterior ocular segment observation image, or further, When the optical axis alignment and the magnification alignment are achieved, the examiner displays the second mark having a size corresponding to the minimum pupil diameter necessary for photographing the eye to be examined by the optical system in the anterior ocular segment observation image. Generated in the anterior ocular segment image so that it can be compared with the pupil size Because it uses a configuration, it performs the correct alignment operation and magnification together easily, can be confirmed mydriasis state of the eye, an excellent effect of obtaining Moreover a simple inexpensive structure.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a configuration of an ophthalmic examination apparatus employing the present invention.
FIG. 2 is an explanatory diagram showing a display example on the monitor of FIG. 1;
[Explanation of symbols]
2 Light source 3 Condenser lens 4 Filter 5 Mirror 6 Lens 7 Ring slit 8 Relay lens 9 Black spot plate 10 Lens 11 Perforated total reflection mirror 12 Objective lens 13 Mirror 14 Strobe 15 Condenser lens 16 Focusing lens 17 Imaging lens 18 Return mirror 20 Field lens 21 Mirror 22 Lens 23 Image sensor 30 Light source 51, 52 Mark L1 Anterior eye lens

Claims (8)

An optical system for acquiring an anterior ocular segment observation image of the eye to be examined;
Means for generating, in the anterior ocular segment observation image, a first mark for alignment with the iris outer diameter of the eye to be examined in the anterior ocular segment observation image obtained by the optical system;
The examiner adjusts the positional relationship between the optical system and the eye to be examined, and aligns the iris outer diameter of the eye to be examined in the first mark and the anterior ocular segment observation image. An ophthalmic examination apparatus characterized in that optical axis alignment and magnification alignment are achieved.   In a state where the optical axis alignment and magnification alignment of the eye to be examined and the optical system have been achieved, the examiner will advance the second mark having a size corresponding to the minimum pupil diameter necessary for photographing the eye to be examined by the optical system. The ophthalmic examination apparatus according to claim 1, wherein the ophthalmic examination apparatus is generated in the anterior ocular segment observation image so as to be compared with a pupil size of the eye to be examined in the ocular region observation image.   In a state where the optical axis alignment and magnification alignment of the eye to be examined and the optical system have been achieved, the measuring means for measuring the pupil size of the eye to be examined in the anterior ocular segment observation image, and the measurement result by the measuring means are displayed and output. The ophthalmic examination apparatus according to claim 1, further comprising a display unit. A warning that compares the measurement result of the measuring means with the minimum pupil diameter necessary for imaging of the subject's eye, and informs the examiner whether or not imaging conditions relating to the pupil diameter of the subject's eye are achieved according to the comparison result The ophthalmic examination apparatus according to claim 3 , further comprising means. The ophthalmic examination apparatus according to claim 3 , wherein the operation of the ophthalmologic photographing apparatus is prohibited or permitted according to a measurement result obtained by the measuring unit. The ophthalmic examination apparatus according to claim 3 , wherein an operation condition of the ophthalmologic photographing apparatus is automatically controlled according to a measurement result by the measurement unit. The ophthalmic examination apparatus according to claim 6 , wherein the operation condition of the ophthalmologic photographing apparatus is a condition relating to brightness of an image at the time of photographing an eye to be examined. Said first and second mark, after the end of comparison with the eye the optical system of the optical axis together and magnification combined or pupil size, of claim 1 or claim 2, characterized in that erasure Ophthalmic examination device.

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