JP3599842B2 - Corneal endothelial cell imaging system - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a corneal endothelial cell photographing apparatus for photographing corneal endothelial cells.
[0002]
[Prior art]
Conventionally, a slit light illumination optical system for irradiating a slit light obliquely toward a cornea of an eye to be examined, and observation and imaging for observing and photographing a corneal endothelial cell image using reflected light from the cornea. With an optical system, a mask that blocks reflected light from the corneal endothelial cell and transmits reflected light from the corneal endothelial cell is provided at a position conjugate with the corneal endothelial cell position with respect to the objective lens of the observation and photographing optical system. A corneal endothelial cell photographing apparatus for observing and photographing corneal endothelial cells is known. The mask has a slit as an opening for transmitting the reflected light from the corneal endothelial cells.
[0003]
[Problems to be solved by the invention]
However, in this conventional corneal endothelial cell imaging apparatus, since the mask is arranged at a position conjugate with the position of the corneal endothelial cell with respect to the objective lens of the observation and imaging optical system, a part of the reflected light from the corneal surface is masked. The corneal endothelial cell image becomes unclear because the reflected light from the corneal surface is considerably larger than the reflected light from the corneal endothelial cells, because the light is transmitted through the slit formed in the mask without being completely blocked. There was a problem that it was easy.
[0004]
The present invention has been made in view of such circumstances, and an object of the present invention is to provide a corneal endothelial cell imaging apparatus capable of obtaining a more clear corneal endothelial cell image.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 provides a slit light irradiation optical system for irradiating a slit light obliquely toward a cornea of an eye to be inspected, and a cornea using reflected light from the cornea. after forming an endothelial cell image, and an observation image taking optical system for performing observing and photographing of corneal endothelium image is imaged on the image plane, the corneal endothelial cells relates objective lens of the observation imaging optical system A mask is provided at a position conjugate with the corneal surface, and a mask for blocking light reflected from the corneal surface is provided at a position conjugate with the surface position of the cornea.
[0006]
With this configuration, when observing the corneal endothelial cells, it is possible to substantially surely block the reflected light from the corneal surface, and a clearer corneal endothelial cell image can be obtained.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, an embodiment of the present invention will be described with reference to the drawings.
[0008]
As shown in FIGS. 1 and 2, the corneal endothelial cell photographing apparatus includes an anterior ocular segment observation optical system 10 for observing an anterior segment of the eye E, an anterior segment illumination light source 1, a corneal endothelial cell illumination optical system 20, Corneal endothelial cell photographing optical system 30, in-focus position detecting light receiving optical system 7, fixation target projecting optical system 2, alignment detecting index projecting optical system 40, alignment detecting index receiving optical system 5, anterior eye observation optical system 10. And light shielding plates 9a and 9b provided in the corneal endothelial cell imaging optical system 30, respectively. The observed and photographed images are displayed on a monitor screen 15 (see FIGS. 5 and 7).
[0009]
The anterior ocular segment observation optical system 10 generally includes a half mirror 11, an objective lens 12, a half mirror 13, and a CCD camera 14, and O1 is the optical axis. The anterior segment of the eye E is illuminated by the anterior segment illumination light source 1. The half mirror 11 forms a part of the alignment detection target projection optical system 40 shown in FIG. The alignment detection target projection optical system 40 includes an alignment target light source 41 (infrared LED), a pinhole 42, a dichroic mirror 43, a projection lens 44, and a half mirror 11, and the pinhole 42 is a focal position of the projection lens 44. Are located in The alignment index light transmitted through the pinhole 42 is reflected by the dichroic mirror 43 and then guided to the projection lens 44 to be converted into a parallel light beam. This parallel light beam is reflected by the half mirror 11 and guided to the cornea C of the eye E to be examined. The dichroic mirror 43 forms a part of the fixation target projection optical system 2, and the fixation target projection optical system 2 includes the fixation target light source 3 (visible LED) and the pinhole 4. The pinhole 4 is arranged at the focal position of the projection lens 44. The fixation target light that has passed through the pinhole 4 passes through the dichroic mirror 43, is converted into a parallel light beam by the projection lens 44, is reflected by the half mirror 11, and is guided to the eye E. The adjustment of the alignment is performed while allowing the subject to fixate the fixation target.
[0010]
The alignment light beam reflected by the cornea C is guided to the objective lens 12 via the half mirror 11 and is collected by the objective lens 12, and a part of the collected light beam passes through the half mirror 13 and passes through the CCD camera 14. Form an image on it. The light-shielding plate 9a provided in the optical path between the half mirror 13 and the CCD camera 14 can be inserted into and removed from this optical path. A light-shielding plate 9b having the same function as the light-shielding plate 9a is provided in the optical path of the corneal endothelial cell photographing optical system 30, and the light-shielding plate 9a is retracted from the optical path of the anterior eye part observation optical system 10 during anterior eye observation. The light shielding plate 9b is inserted into the optical path of the corneal endothelial cell imaging optical system 30. At the time of corneal endothelial cell imaging, the light-shielding plate 9a is inserted into the optical path of the anterior ocular segment observation optical system 10, and the light-shielding plate 9b is retracted from the optical path of the corneal endothelial cell imaging optical system 30. And the optical path of the corneal endothelial cell imaging optical system 30 are switched. The half mirror 13 forms a part of the alignment detecting index receiving optical system 5.
[0011]
The alignment detecting index receiving optical system 5 includes a two-dimensional PSD (position sensor) 6 as a position detecting means, and is formed by the alignment index light at a substantially intermediate position between the corneal vertex P and the corneal curvature center Q with respect to the objective lens 12. Is arranged at a position conjugate with the virtual image R. The corneal reflected light based on the alignment index light is guided to the objective lens 12. Part of the light beam condensed by the objective lens 12 is reflected by the half mirror 13 and forms an image on the two-dimensional PSD 6. At this time, the amount of deviation between the left and right (X direction) and the up and down (Y direction) of the subject's eye E with respect to the apparatus main body is detected based on the detection position of the signal based on the virtual image R 'of the alignment index light on the two-dimensional PSD 6. Here, when the signal based on the virtual image R ′ of the alignment index light is within a predetermined range of the two-dimensional PSD 6, the XY alignment is completed.
[0012]
Illumination light from the anterior segment illumination light source 1 is reflected by the cornea C, transmitted through the half mirror 11, and guided to the objective lens 12. A part of the light beam transmitted through the objective lens 12 is transmitted through the half mirror 13 and formed into an image on the CCD camera 14 by the objective lens 12. The signal detected by the CCD camera 14 is sent to a monitor. When the alignment between the eye E and the corneal endothelial cell photographing device is substantially aligned, an image R ″ of the alignment index light by the virtual image R is also formed on the CCD camera 14 at the same time. Is displayed at the same time as the anterior segment image E ′ of the image and the virtual image R ″ of the alignment index light. Here, FIG. 4 shows the anterior ocular segment image E ′ and the virtual image R ″ of the alignment index light displayed on the screen 15 of the monitor. In FIG. 4, reference symbol A denotes an annular pattern image indicating an allowable range of XY alignment in the left-right direction (X direction) and the up-down direction (Y direction), and is an anterior eye image E ′ of the subject's eye on the monitor screen. Displayed at the same time. Illustration of an optical system for forming the annular pattern image is omitted. The examiner performs XY alignment by moving the main body (not shown) of the corneal endothelial cell image photographing device so that the virtual image R ″ falls within the range of the annular pattern image A. Next, Z alignment, which is alignment in the front-rear direction (Z direction), is performed based on a signal obtained by a focus position detection light receiving optical system 7 described later.
[0013]
The corneal endothelial cell illumination optical system (slit light irradiation optical system) 20 includes an observation illumination optical system and a photographing illumination optical system, and the observation illumination optical system includes an observation light source (infrared LED) 21 and a slit 22. , A dichroic mirror 23 and an objective lens 24, and O2 is its optical axis. The observation light beam transmitted through the slit 22 is reflected by the dichroic mirror 23 and guided to the objective lens 24. The light beam condensed by the objective lens 24 illuminates the cornea C. The dichroic mirror 23 and the objective lens 24 are shared with the illumination optical system for photography. The photographing illumination optical system includes a photographing light source (xenon lamp) 25, a condenser lens 26, a slit 27, and a condenser mirror 27 '. The illumination light emitted from the photographing light source 25 is condensed by the condenser lens 26. The illumination light is used as photographing light, passes through the slit 27 to become slit illumination light, and out of this slit illumination light, slit illumination light in the visible wavelength range passes through the dichroic mirror 23, and slit illumination light in the visible wavelength range is emitted. It is guided to the objective lens 24. The cornea C is illuminated by the slit illumination light transmitted through the objective lens 24. Here, the state of reflection by the cornea C is shown in FIG. The light flux reflected by the slit illumination light from the cornea C can be classified into S1, which is the boundary surface between air and the cornea C, corneal endothelial cells S2, and reflected light fluxes R1, R2, and R3 from the corneal stroma S3. The amount of the reflected light beam R1 is the largest, the amount of the reflected light beam R2 is relatively smaller than the amount of the reflected light beam R1, and the amount of the reflected light beam R3 is the smallest.
[0014]
The corneal endothelial cell photographing optical system 30 includes an objective lens 31M, a half mirror 32, a mask 33 for shielding light reflected from the corneal surface, a mirror 34, a relay lens 35M, a light shielding plate 9b, a mirror 36, and a CCD camera 14. O3 is this optical axis. Here, the mask 33 is provided at a position conjugate with the approximate surface position of the cornea C with respect to the objective lens 31M. The slit illumination light reflected by the cornea C is guided to the objective lens 31M. Some of the reflected light fluxes R1, R2, and R3 guided to the objective lens 31M pass through the half mirror 32 and are guided to the mask 33. The corneal endothelial cell image is formed in the air at a position (image plane) M0 conjugate with the corneal endothelial cell image with respect to the objective lens 31M. The mask 33 has a slit 33a. The slit 33a has a role of transmitting the reflected light beam from the corneal endothelial cell, and the mask 33 reliably shields the reflected light beam R1 from the corneal surface, that is, from the corneal surface which is harmful to the formation of the corneal endothelial cell image. The function of the mask 33 will be described in detail later in comparison with the case where the mask 33 is disposed at a position conjugate with the corneal endothelial cells. The reflected light transmitted through the mask 33 is reflected by the mirror 34, guided to the relay lens 35M, relayed by the relay lens 35M, reflected by the mirror 36, and imaged on the CCD camera 14.
[0015]
The half mirror 32 constitutes a part of the focus position detecting light receiving optical system 7. The in-focus position detecting light receiving optical system 7 includes a line sensor 8 as in-focus position detecting means. The line sensor 8 is disposed at a position conjugate with the corneal endothelial cell image with respect to the half mirror 32. The part is reflected by the half mirror 32 and forms an image on the line sensor 8. When the corneal endothelial cell photographing apparatus is properly alaminated with respect to the eye E and the in-focus position is detected by the line sensor 8, the corneal endothelial cell image 45 is clearly displayed on the monitor screen 15 as shown in FIG. What is displayed. At this time, since the mask 33 is displaced from the position M0, it is displayed on the screen 15 as blurred. In FIG. 7, reference numeral 47 denotes an optical image by reflected light from the corneal stroma, and reference numeral 47 ′ denotes a boundary portion of an unclear image at the left opening edge (described later) of the mask 33. This is a sectional direction of the cornea C.
[0016]
Next, the arrangement position of the mask 33 and the state of blocking the reflected light from the corneal surface will be conceptually described with reference to FIG.
[0017]
FIG. 5 shows a case where the mask 33 is provided at a position M1 substantially conjugate with the corneal endothelial cells, at a position M3 conjugate with the corneal surface having an average thickness, and at a substantially middle position M2 between the positions M1 and M3. Have been. When the mask 33 is disposed at the position M1, the reflected light flux (the hatched portion) R1 from the corneal surface transmits through the mask 33. However, when the mask 33 is disposed at the position M3, the reflected light flux is transmitted. R1 can be completely blocked, and when the mask 33 is arranged at the position M2, the reflected light beam R1 cannot be completely blocked, but the influence of the reflected light beam R1 can be reduced. This is because, at the position M1, the reflected light flux from the corneal surface is spread due to blur, and even if the mask 33 is disposed at the position M1, part of the reflected light R1 from the corneal surface passes through the opening 33a. Since the light cannot be completely shielded from light, a part of the reflected light R1 is mixed with the reflected light from the corneal endothelial cells. At this time, if the licensor 8 is provided at the position M1, the light amount distribution is as shown in FIG. Next, when the mask 33 is provided at the position M3, the spread of the reflected light R1 (R1 ') from the corneal surface is narrowed (the reflected light R1 (R1') converges because the mask 33 is at a conjugate position with the corneal surface. State), the reflected light R1 (R1 ′) from the corneal surface is reliably blocked by the mask 33. At this time, if the licensor 8 is provided at the position M3, the light amount distribution is as shown in FIG. 6B. Further, when the mask 33 is disposed at an intermediate position between the position M1 and the position M3, the mask 33 is inferior to the light shielding state of the reflected light R1 (R1 ′) when the mask 33 is disposed at the position M3. Is better than the state in which the reflected light R1 (R1 ′) is shielded when. At this time, if the licensor 8 is provided at the position M2, the light amount distribution is as shown in FIG. 6C. If the reflected light R1 cannot be completely shielded by the mask 33, the reflectance of the corneal surface is about 100 times that of the corneal endothelial cells, so that the image of the captured corneal endothelial cells cannot be unclear. Will not get.
[0018]
In FIG. 6 (A), the symbol b indicates the left edge (upper edge) of the opening 33a when the mask 33 is disposed at the position M1 in FIG. 5, and in FIG. 6 (B), the symbol b ′. 5 shows the left edge (upper edge) of the opening 33a when the mask 33 is disposed at the position M3 in FIG. 5, and in FIG. Shows the left edge (upper edge) of the opening 33a when the mask 33 is disposed, and when the mask 33 is changed to the position M1, the position M2, and the position M3, the slit width of the opening 33a is changed. Is desirable in order to avoid a decrease in the amount of the reflected light beam forming the light beam. Since the line sensor 8 shown in FIG. 1 has a conjugate relationship with the position M1 (position M0), the light amount distribution detected by the line sensor 8 corresponds to FIG. 6A, and therefore, FIG. The image shown is formed in the air at the location where the line sensor 8 shown in FIG. 1 is disposed, and the details will be described later.
[0019]
In FIG. 6A, reference symbol P1 indicates a peak portion of reflected light from the corneal surface, and reference symbol P3 indicates a peak portion of reflected light from a portion corresponding to a corneal endothelial cell image. The reason why the shape of the peak portion P3 shown in FIG. 6A is sharper and the light amount is larger than that in FIGS. 6B and 6C is because the corneal endothelial cells are more in focus. The reason that the amount of light on the peak portion P1 side is large and the symmetry is broken is that a part of the reflected light R1 (R1 ′) from the corneal epidermis is mixed. The reason why the shape of the peak portion P1 shown in FIG. 6 (B) is sharper and the light amount is larger than that in FIGS. 6 (A) and 6 (C) is because the corneal surface is more in focus. This is because the image of the corneal endothelium is blurred at the position M3. The peaks P1 and P3 shown in FIG. 6C are in an intermediate state between the peaks P1 and P3 shown in FIGS. 6A and 6B. In FIG. 6D, reference numeral 46 denotes an optical image of light reflected from the corneal surface, reference numeral 47 denotes an optical image of the corneal substance as described above, and reference numeral 45 denotes an image of corneal endothelial cells. In the light amount distribution detected by the line sensor 8, the image formed by the corneal epidermis becomes unclear but the peak portion P3 is easily detected. Therefore, when the peak portion P3 is located at the in-focus position a, it is detected. The Z alignment of the corneal endothelial cell image photographing apparatus with respect to the optometry E is defined as completed, and the difference between the position a ′ of the peak portion P3 at the time of out-of-focus indicated by the broken line in FIG. A shift amount in the direction (Z direction) is detected.
[0020]
The examiner performs alignment in the X and Y directions and alignment in the Z direction while viewing the image on the monitor screen 15 shown in FIG. 4 while fixing the fixation target on the subject. When all the alignments are completed, the displacement amount in the Z direction becomes zero, so that the light shielding plate 9a and the light shielding plate 9b are interlocked and automatically inserted and removed, and switched to the corneal endothelial cell image photographing optical system 30. In addition, the light source 25 for photographing automatically emits light. Thus, a corneal endothelial cell image 45 is captured. This corneal endothelial cell image 45 is displayed on the monitor screen 15 (see FIG. 7). Since the corneal endothelial cell image 45 is surely prevented from being mixed with the reflected light from the corneal surface, the corneal endothelial cell image 45 is clearer than before.
[0021]
As described above, in the embodiment of the invention described above, it has been described that the corneal endothelial cell photographing optical system is automatically switched to the corneal endothelial cell photographing optical system when the alignment is completed, and the photographing is performed. Switching to an endothelial imaging system and imaging are also possible.
[0022]
Further, in the embodiment of the present invention, the description has been made assuming that one mask 33 is arranged at the surface position and the conjugate position on the assumption that the cornea has an average thickness. However, the arrangement position of the mask 33 is variable. A mechanism that can be disposed at a position conjugate with the surface position of the cornea according to the thickness of the cornea may be provided. Further, a mechanism may be provided in which the arrangement position of the mask 33 is fixed and the slit width of the opening 33a is continuously changed. Further, the slit width of the opening 33a of the mask 33 may be changed by a mask having a plurality of openings having different widths. Further, another mask may be provided at a position conjugate with the corneal endothelial cell.
[0023]
Japanese Patent Laid-Open No. Hei 6-327634 discloses a method of measuring the corneal thickness from the peak interval of the signal due to the surface reflection of the cornea and the reflection of the endothelial cells. Alternatively, a mechanism for changing the slit width of the opening 33a may be provided. The measured value may be output to a monitor and displayed on the screen 15, and the examiner may manually change the arrangement position of the mask 33 or the slit width of the opening 33a.
[0024]
Further, the infrared LED described as the infrared light source may be replaced with a configuration using a visible light source such as a halogen lamp and an infrared filter. Furthermore, it has been described that the examiner performs alignment by observing the anterior eye image displayed on the monitor. However, based on the alignment detection signal and the in-focus position detection signal, the motor drive unit automatically performs the alignment. The configuration may be such that the corneal endothelial cell image photographing apparatus is aligned with E.
[0025]
【The invention's effect】
As described above, the corneal endothelial cell imaging apparatus of the present invention has an effect that a clearer corneal endothelial cell image can be obtained.
[Brief description of the drawings]
FIG. 1 is a diagram showing a main part of a planar arrangement configuration of an optical system of a corneal endothelial cell photographing apparatus according to the present invention.
FIG. 2 is a diagram showing a main part of a side arrangement configuration of an optical system of the corneal endothelial cell photographing apparatus of the present invention.
FIG. 3 is an explanatory diagram of a reflection state by a cornea.
FIG. 4 is an explanatory diagram showing an anterior segment image of the subject's eye displayed on a monitor.
FIG. 5 is an optical schematic diagram for explaining a state in which corneal reflected light is shielded when the arrangement position of the mask is changed.
FIGS. 6A, 6B, and 6C are graphs showing a relationship between a light amount distribution of corneal reflected light and a detection position of the line sensor when a line sensor is temporarily disposed at a mask installation position. FIG. 2D is an explanatory diagram showing a positional relationship between the line sensor shown in FIG. 1 and a corneal endothelial cell image.
FIG. 7 is an explanatory diagram showing a corneal endothelial cell image of the subject's eye displayed on a screen of a monitor.
[Explanation of symbols]
E: eye to be examined C: cornea 20: corneal endothelial cell illumination optical system 45: corneal endothelial cell image 30: corneal endothelial cell photographing optical system 33: mask

Claims (1)

A slit light irradiation optical system for irradiating slit light obliquely toward the cornea of the eye to be examined, and a corneal endothelial cell image was formed using reflected light from the cornea, and then formed on an image plane. An observation optical system for observing and photographing a corneal endothelial cell image, and providing a mask at a position conjugate to the corneal endothelial cell with respect to the objective lens of the observation photographic optical system; A corneal endothelial cell photographing apparatus characterized in that a mask for blocking reflected light from a corneal surface is provided at a position.

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