JP2017060809A - Ophthalmologic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ophthalmologic apparatus capable of measuring an accurate value of a thickness of a cornea.SOLUTION: An ophthalmologic apparatus comprises: a cornea thickness measurement optical system 11 that obliquely irradiates a cornea C of a subject's eye E with slit light; a cornea thickness detection system 12 that receives reflected light from the cornea C to detect a light volume; and a control apparatus 49. The control apparatus 49 is capable of changing a light volume of the slit light. The control apparatus makes two steps of slit light having different light volumes be radiated to the cornea D; acquires a light volume peak position of reflected light reflected at an endothelium of the cornea C from one slit light having the larger light volume of the two steps of slit light; acquires a light volume peak position of the reflected light reflected at the endothelium of the cornea C from the other slit light having the smaller light volume of the two steps of slit light; and measures a thickness of the cornea C in a non-contact manner from a difference between the two light volume peak positions.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an ophthalmologic apparatus that performs imaging of corneal endothelial cells and measurement of corneal thickness without contact.

  The corneal endothelial cells are imaged by irradiating illumination light from an oblique direction with respect to the cornea and capturing light reflected by the corneal endothelium with a light receiving element such as a CCD.

  When the illumination light for photographing is irradiated onto the cornea, a part of the illumination light is reflected on the cornea surface, and a part of the light transmitted through the cornea is reflected on the cornea endothelium.

  In order to photograph endothelial cells, the light reflected from the corneal surface and the light reflected from the corneal endothelium are separated, and the reflected light signal reflected from the separated corneal endothelium is captured by a light receiving element such as a CCD. There is a need to.

  For this reason, the illumination light used at the time of photographing is slit light, and in order to separate the reflected light from the corneal surface and the reflected light from the corneal endothelium, the illumination light is irradiated obliquely with respect to the cornea. Yes.

  When measuring the film thickness of the cornea, first, light quantity waveform data 65 as shown in FIG. 6 is acquired based on the reflected light signal from the cornea surface and the reflected light signal from the corneal endothelium. Next, based on the light amount waveform data 65, the light amount peak position where the light amount of the endothelial reflected light 66 reflected by the corneal endothelium is maximized, and the light amount of the surface reflected light 67 reflected by the cornea surface becomes the maximum. The light quantity peak position is obtained simultaneously, and the film thickness of the cornea is obtained from the difference between the obtained light quantity peak positions.

  However, the light quantity of the surface reflected light 67 is several tens times larger than the light quantity of the endothelial reflected light 66, and the surface reflected light 67 is a saturated signal, and an accurate peak position cannot be obtained. Therefore, conventionally, the center of gravity of the surface reflected light 67 that has been saturated is obtained, and the center of gravity is used as the light intensity peak position of the surface reflected light 67, making it difficult to accurately measure the film thickness of the cornea.

JP 2004-290286 A

  In view of such circumstances, the present invention provides an ophthalmologic apparatus capable of measuring an accurate value of the cornea thickness.

The present invention includes a corneal thickness measurement optical system for irradiating a slit light from obliquely toward the cornea of the eye, the corneal thickness detection system for detecting the amount by receiving the reflected light from the cornea, and a control device And the control device is capable of changing the light amount of the slit light, irradiating the cornea with two-stage slit light having different light amounts, and one of the two-stage slit light having a large light amount. To obtain the light intensity peak position of the reflected light reflected by the endothelium of the cornea, and obtain the light intensity peak position of the reflected light reflected from the surface of the cornea from the other slit light having a small light quantity, and obtain two light intensity peak positions. Therefore, the present invention relates to an ophthalmologic apparatus that measures the film thickness of the cornea in a non-contact manner.

  Further, in the present invention, the one slit light is a light amount capable of obtaining a peak position of the light amount reflected by the endothelium of the cornea, and the other slit light is a peak of the light amount reflected by the surface of the cornea. The present invention relates to an ophthalmologic apparatus that is a light quantity capable of acquiring a position.

  Furthermore, the present invention provides an ophthalmologic apparatus that can change the light quantity of the slit light in a plurality of stages, and the control device selects a stage at which at least the peak position of the reflected light quantity reflected by the surface of the cornea can be acquired. It is concerned.

According to the present invention, a corneal thickness measuring optical system for irradiating a slit light from obliquely toward the cornea of the eye, the corneal thickness detection system for detecting the amount by receiving the reflected light from the cornea, the control device The control device can change the light quantity of the slit light, irradiates the cornea with two stages of slit light having different light quantities, and the one of the two stages of slit light having the larger light quantity. The light quantity peak position of the reflected light reflected by the corneal endothelium is obtained from the slit light, and the light quantity peak position of the reflected light reflected by the surface of the cornea is obtained from the other slit light having a small quantity of light, and the two light quantities are obtained. Since the film thickness of the cornea is measured in a non-contact manner from the difference in peak position, it is possible to obtain the accurate light amount peak position of the reflected light from the cornea endothelium and the reflected light from the surface of the cornea, Measure the exact thickness of the cornea It can be.

  According to the invention, the one slit light is a light quantity capable of obtaining a peak position of the light quantity reflected by the endothelium of the cornea, and the other slit light is a light quantity reflected by the surface of the cornea. Therefore, it is possible to obtain an accurate light amount peak position of reflected light from the corneal endothelium and reflected light from the surface of the cornea, and an accurate film thickness of the cornea. Can be measured.

  Furthermore, according to the present invention, the light quantity of the slit light can be changed in a plurality of stages, and the control device selects a stage where at least the light quantity peak position of the reflected light reflected by the surface of the cornea can be acquired. Even if the amount of reflected light from the surface of the cornea varies due to individual differences in the thickness of the cornea, etc., the light intensity peak position of the reflected light from the surface of the cornea is obtained using the amount of light of the slit light. It exhibits an excellent effect that the light quantity can be optimized.

1 is a schematic configuration diagram of an ophthalmologic apparatus according to an embodiment of the present invention. It is a schematic block diagram of the control apparatus of the said ophthalmologic apparatus. It is a flowchart explaining the film thickness measurement of a cornea by the said ophthalmologic apparatus. It is explanatory drawing explaining the 1st light quantity waveform data for calculating | requiring the light quantity peak position of the reflected light from the endothelium of a cornea. It is explanatory drawing explaining the 2nd light quantity waveform data for calculating | requiring the light quantity peak position of the reflected light from the surface of a cornea. It is explanatory drawing explaining the light quantity waveform data for calculating | requiring the film thickness of the conventional cornea.

  Embodiments of the present invention will be described below with reference to the drawings.

  First, a schematic configuration of an ophthalmologic apparatus according to an embodiment of the present invention will be described.

  FIG. 1 is a schematic configuration diagram showing a basic optical system of the ophthalmologic apparatus.

  In FIG. 1, E denotes an eye to be examined, and 2 denotes an apparatus main body that can move in three axis directions of XYZ. Inside the apparatus main body 2, an anterior ocular segment observation optical system 3, a photographing illumination optical system 4, a photographing optical system 5, a Z alignment projection system 6, a Z alignment detection system 7, and an XY alignment projection system 8. A fixation projection system 9, an XY alignment detection system 10, a corneal thickness measurement optical system 11, and a corneal thickness detection system 12.

  The XY alignment detection system 10 is also used as the anterior ocular segment observation optical system 3, the corneal thickness measurement optical system 11 is also used as the Z alignment projection system 6, and the corneal thickness detection system 12 is used as the Z The alignment detection system 7 is also used.

  Further, the configuration will be described.

  In FIG. 1, the anterior ocular segment observation optical system 3 is arranged corresponding to the left and right eye E, respectively, and the main optical axis O1 of the anterior ocular segment observation optical system 3 is respectively set to the eye E. The main optical axis O1 is set so as to pass through the apex P of the cornea C of the eye E to be examined.

  A half mirror 15, an objective lens 16, and a light receiving element 17 are provided from the eye E side on the main optical axis O1. A CCD element is used as the light receiving element 17, and the light receiving element 17 can be formed by reflecting light projected onto the cornea C by the XY alignment projection system 8 with respect to the objective lens 16. It is arranged at a position conjugate with the virtual image. The main optical axis O1, the objective lens 16, and the light receiving element 17 also constitute the XY alignment detection system 10.

  The photographing illumination optical system 4 has a light projection optical axis O2 passing through the apex P, and the light projection optical axis O2 is inclined by θ1 (30 °) with respect to the main optical axis O1.

  A photographing illumination light source 21, a condensing lens 22, a slit plate 23, a dichroic mirror 24, and an objective lens 25 are provided on the projection optical axis O2 from the position away from the eye E toward the eye E. It has been.

  As the photographing illumination light source 21, a light emitting diode (LED) that emits visible light, for example, green light, is used. The slit plate 23 is provided with a slit hole, and visible light emitted from the photographing illumination light source 21 is irradiated as slit light. The slit plate 23 and the cornea C are conjugate with respect to the objective lens 25.

  The slit width formed by the slit plate 23 is limited to a width that allows separation of the reflected light reflected by the surface of the cornea C and the reflected light reflected by the corneal endothelium.

  In the Z alignment projection system 6, a light source 26, a condenser lens 27, and a slit plate 28 are provided on the optical axis O <b> 3 branched by the dichroic mirror 24. As the light source 26, a light emitting diode (LED) emitting infrared light is used. The brightness of the light source 26 can be changed in a plurality of stages. For example, the brightness can be changed in five stages of 1/10, 1/20, 1/30, 1/40, and 1/50.

  The slit plate 28 and the cornea C are in a conjugate position with respect to the objective lens 25. The dichroic mirror 24 transmits green light and reflects infrared light. The optical axis O3, the dichroic mirror 24, the light source 26, the condenser lens 27, and the slit plate 28 also constitute the corneal thickness measurement optical system 11.

  The photographing optical system 5 has a photographing optical axis O4 that is symmetric with respect to the light projecting optical axis O2 with respect to the main optical axis O1, and the photographing optical axis O4 transmits the vertex P. Accordingly, the light projecting optical axis O2 and the photographing optical axis O4 are in the relationship between the incident optical axis and the reflected optical axis with respect to the vertex P, and the photographing optical axis O4 is θ1 (30 with respect to the main optical axis O1). °) Inclined.

  On the photographing optical axis O4, there are an objective lens 31, a dichroic mirror 32, and a mirror 34 from the eye E side, and the photographing optical axis O4 is deflected by the mirror 34 and is deflected on the photographing optical axis O4. Is provided with a focus adjusting relay lens 35 and a mirror 37, and the light beam reflected by the mirror 37 is imaged on the image sensor 36. The photographing optical system 5 constitutes an image pickup unit 19.

  The image sensor 36 is provided with an inclination of θ2 (15 °) with respect to the photographing optical axis O4. The tilt direction of the image sensor 36 is the same as the tilt direction of the inner surface to be photographed with respect to the photographing optical axis O4.

  The relay lens 35 can be displaced along the photographing optical axis O4, and the position of the relay lens 35 is adjusted along the photographing optical axis O4 by a focusing mechanism 39. The cornea C and the image sensor 36 are in a conjugate position with respect to the objective lens 31.

  A relay lens 40 and a light receiving sensor 38 are provided on the optical axis O5 reflected and deflected by the dichroic mirror 32. The light receiving sensor 38 is a one-dimensional sensor such as a line sensor of 2048 pixels, for example, and the light receiving sensor 38 is conjugated with respect to the cornea C and the objective lens 31.

  The dichroic mirror 32 has an optical characteristic of reflecting infrared light and transmitting green light, and the infrared light emitted from the light source 26 and reflected by the cornea C is guided to the light receiving sensor 38. It is burned. The dichroic mirror 32, the relay lens 40, and the light receiving sensor 38 constitute the Z alignment detection system 7. The optical axis O5, the dichroic mirror 32, the relay lens 40, and the light receiving sensor 38 also constitute the corneal thickness detection system 12.

  Next, the XY alignment projection system 8 will be described.

  A relay lens 41 and a dichroic mirror 42 are provided on the optical axis O6 branched by the half mirror 15, and a relay lens 47 and an XY alignment light source 46 are provided on the reflected optical axis of the dichroic mirror 42. Yes. The XY alignment light source 46 emits infrared light, and the dichroic mirror 42 reflects infrared light and transmits visible light.

  A fixation target 43 is provided on the passing optical axis of the dichroic mirror 42. The fixation target 43 may be a graphic pattern illuminated with visible light, or may be a light source that emits visible light. The fixation target 43 is projected as infinite light by the relay lens 41 so that the normal eye E can be fixed, or is projected with divergent light so that the myopic eye E can be fixed. Also good. The half mirror 15, the relay lens 41, the fixation target 43, etc. constitute the fixation projection system 9.

  The result of light reception by the light receiving element 17 and the result of light reception by the light receiving sensor 38 are detected by the alignment detection unit 48, and the detection result is output to the control unit 49. The control unit 49 controls the main body driving unit 52 based on the detection result, moves the apparatus main body 2 in a required direction of XYZ, and executes alignment between the eye E to be examined and the apparatus main body 2.

  Further, after the alignment is completed, the light quantity waveform conversion unit 50 detects the result of light reception by the light receiving sensor 38. The light quantity waveform conversion unit 50 A / D converts continuous light reception signals into light quantity waveform data, and outputs them to the control unit 49. The controller 49 measures the film thickness of the corneal endothelium based on the light intensity waveform data input by the light intensity waveform converter 50.

  FIG. 2 shows an outline of the control device 51 of the ophthalmologic apparatus.

  The control device 51 mainly includes the imaging unit 19, the alignment detection unit 48, the light amount waveform conversion unit 50, the light source 26, the main body drive unit 52, a storage unit 53, a display unit 54, and an operation unit 55. Yes.

  When an alignment detection result is input from the alignment detection unit 48, the control unit 49 drives the main body driving unit 52 based on the detection result to displace the apparatus main body 2 in the alignment direction. The control unit 49 controls the imaging unit 19 to acquire an image of endothelial cells by the imaging unit 19. The image acquired by the imaging unit 19 is sent to the control unit 49, subjected to required image processing, stored in the storage unit 53, or displayed on the display unit 54.

  After the alignment is completed, the control unit 49 controls lighting so that the light amount of the light source 26 becomes a light amount (hereinafter referred to as a reference light amount) at which the peak position of reflected light from the endothelium of the cornea C can be acquired. When the detection result, that is, the light amount waveform data of the reflected light from the cornea C is input from the light amount waveform conversion unit 50 in the state of being lit with the reference light amount, the control unit 49 displays the input light amount waveform data. 4 is stored in the storage unit 53 as first light intensity waveform data 57 as shown in FIG.

  The controller 49 controls the lighting of the light source 26 and gradually reduces the light amount of the light source 26 until the reflected light from the surface of the cornea C becomes a light amount that does not saturate. Reduce to / 20. When the light amount waveform data of the reflected light from the cornea C is input from the light amount waveform conversion unit 50 with the light amount of the light source 26 decreased, the control unit 49 displays the input light amount waveform data as shown in FIG. The second light quantity waveform data 58 is stored in the storage unit 53 as shown in FIG.

  Further, the control unit 49 obtains a maximum value (peak value) of the light amount of the endothelial reflected light 59 from the corneal endothelium from the first light amount waveform data 57 and the second light amount waveform data 58 on the light receiving sensor 38. And a light amount peak position 63 that is a position on the light receiving sensor 38 where the maximum value (peak value) of the light amount of the surface reflected light 62 from the cornea surface is obtained. The film thickness of the corneal endothelium is measured based on the light quantity peak position on the light receiving sensor 38 and the pixel pitch of the light receiving sensor 38.

  The operation unit 55 inputs / outputs necessary conditions, an instruction to start photographing, and the like to the control unit 49.

  Next, measurement of the film thickness of the cornea using the ophthalmologic apparatus will be described using the flowchart of FIG.

  STEP: 01 When an instruction to start measuring the film thickness of the cornea C is input from the operation unit 55, first, the control unit 49 determines whether or not the first measurement.

  STEP: 02 When it is determined that the measurement is the first time in STEP: 01, the control unit 49 controls the lighting of the light source 26 and turns on the light source 26 with a reference light amount.

  STEP: 03 The slit light irradiated from the light source 26 through the slit plate 28 and reflected by the cornea C is received by the light receiving sensor 38 as a continuous analog reflected light signal, and the light amount waveform converting unit 50 Is input. The light quantity waveform conversion unit 50 converts the input reflected light signal into the first light quantity waveform data 57 as shown in FIG. 4 by performing A / D conversion. The control unit 49 stores the first light amount waveform data 57 converted by the light amount waveform converting unit 50 in the storage unit 53.

  STEP: 04 When STEP: 03 ends, the determination of STEP: 01 is made again. If it is determined in STEP: 01 that the measurement is not the first time, the control unit 49 controls the lighting of the light source 26, and the peak value of the surface reflected light 62 appears in the second light quantity waveform data 58. The light amount is decreased stepwise until the light amount peak position 63 can be acquired. For example, the control unit 49 turns the light source 26 on by reducing it to 1/20 of the reference light amount.

  STEP: 05 The slit light emitted from the light source 26 through the slit plate 28 and reflected by the cornea C is received by the light receiving sensor 38 as a continuous analog reflected light signal, and the light amount waveform converting unit 50 Is input. The light quantity waveform converter 50 converts the input reflected light signal into the second light quantity waveform data 58 as shown in FIG. 5 by A / D conversion. The controller 49 stores the second light amount waveform data 58 converted by the light amount waveform converter 50 in the storage unit 53.

  (Step 06) When the first light amount waveform data 57 and the second light amount waveform data 58 are stored in the storage unit 53, the control unit 49 next stores the first light amount waveform data 57 and the second light amount waveform data. Based on the data 58, the light intensity peak position 61 on the light receiving sensor 38 of the endothelial reflected light 59 reflected by the endothelium of the cornea C and the surface reflected light 62 reflected by the surface of the cornea C are reflected. The light quantity peak position 63 on the light receiving sensor 38 is obtained.

  As shown in FIG. 4, the first light quantity waveform data 57 irradiated with the slit light with the normal light quantity obtains the light quantity peak position 61 of the endothelial reflected light 59, but the surface reflected light 62 is saturated. The light quantity peak position 63 cannot be obtained. Accordingly, the control unit 49 acquires only the light amount peak position 61 of the endothelial reflected light 59 from the first light amount waveform data 57.

  Further, as shown in FIG. 5, the light amount is decreased stepwise until the light amount peak position 63 of the surface reflected light 62 can be acquired in the second light amount waveform data 58. For example, in the second light amount waveform data 58 irradiated with slit light whose light amount is reduced to 1/20, the light amount peak position 61 of the endothelial reflected light 59 cannot be obtained due to insufficient light amount, but the surface reflection The light 62 can obtain the light quantity peak position 63 without being saturated. Accordingly, the control unit 49 acquires only the light amount peak position 63 of the surface reflected light 62 from the second light amount waveform data 58.

  STEP: 07 Finally, the control unit 49 determines the light amount peak position 61 of the endothelial reflected light 59 acquired from the first light amount waveform data 57 and the surface reflected light 62 acquired from the second light amount waveform data 58. The thickness of the cornea C is calculated from the difference between the calculated light peak positions 61 and 63 and the pixel pitch of the light receiving sensor 38, and the measurement of the thickness of the cornea C is completed. To do.

  As described above, in this embodiment, the light quantity of the light source 26 can be changed, and the light quantity peak position 61 of the endothelial reflected light 59 can be acquired by changing the light quantity of the light source 26. The light quantity waveform data 57 and the second light quantity waveform data 58 that can obtain the light quantity peak position 63 of the surface reflected light 62 can be obtained.

  Accordingly, the accurate light quantity peak positions 61 and 63 of the endothelial reflected light 59 and the surface reflected light 62 can be acquired, and the accurate film thickness of the cornea C can be measured.

  Further, since the light quantity of the light source 26 can be changed in a plurality of stages, for example, 1/10, 1/20, 1/30, 1/40, and 1/50, the thickness of the cornea C can be changed. Even if the light quantity peak position 63 of the surface reflected light 62 cannot be obtained with a normal light quantity of 1/20 due to individual differences, the light quantity peak position 63 can be obtained. The possible second light quantity waveform data 58 can be obtained.

  In this embodiment, the light quantity of the light source 26 can be controlled in five steps, but it goes without saying that it can be controlled in six steps or more.

  In this embodiment, the light receiving sensor 38 is a one-dimensional sensor such as a line sensor, but it goes without saying that a two-dimensional sensor may be used.

  In the present embodiment, the light amount of the light source 26 that can be obtained by the light amount peak position 61 of the endothelial reflected light 59 is used as a reference light amount, but the light amount peak position 63 of the surface reflected light 62 is obtained. The possible light quantity of the light source 26 may be set as a reference light quantity, and the reference light quantity may be increased stepwise until the light quantity peak position 61 of the endothelial reflected light 59 can be acquired.

  Alternatively, after the thickness of the cornea C is measured, the first light quantity waveform data 57 may be acquired again, and the first light quantity waveform data 57 may be compared with the previously acquired first light quantity waveform data 57. By comparing the first light quantity waveform data 57, it is confirmed whether or not the eye E is moving between the acquisition of the first light quantity waveform data 57 and the acquisition of the second light quantity waveform data 58. And the accuracy of measurement of the film thickness of the cornea C can be further increased.

  Furthermore, when it is determined that the eye E is moving when the light amount waveform data 57 are compared with each other, the processing of STEP: 01 to STEP: 07 is repeated a plurality of times, and the measured plurality of the above-described eye amounts E are measured. The film thickness of the cornea C may be averaged to obtain the film thickness of the cornea C.

2 apparatus main body 9 fixation projection system 11 corneal thickness measurement optical system 12 corneal thickness detection system 26 light source 49 control unit 50 light amount waveform conversion unit 51 control device 53 storage unit 57 first light amount waveform data 58 second light amount waveform data 59 endothelial reflection Light 61 Light intensity peak position 62 Surface reflected light 63 Light intensity peak position

Claims (3)

Comprising the corneal thickness measuring optical system for irradiating a slit light from obliquely toward the cornea of the eye, the corneal thickness detection system for detecting the amount by receiving the reflected light from the cornea, and a control device, the The control device can change the light amount of the slit light, irradiates the cornea with two-stage slit light having different light amounts, and from one of the two-stage slit light having a large light amount, The light intensity peak position of the reflected light reflected by the endothelium is acquired, the light intensity peak position of the reflected light reflected by the surface of the cornea is acquired from the other slit light having a small light intensity, and the non- difference is calculated from the difference between the two light intensity peak positions. An ophthalmic apparatus that measures the film thickness of the cornea by contact .   The one slit light is a light amount capable of acquiring the peak position of the light amount reflected by the corneal endothelium, and the other slit light is capable of acquiring the peak position of the light amount reflected by the surface of the cornea. The ophthalmic apparatus according to claim 1, which is a light amount.   3. The ophthalmologic according to claim 1, wherein the amount of light of the slit light can be changed in a plurality of stages, and the control device selects a stage at which at least a light intensity peak position of reflected light reflected by the surface of the cornea can be acquired. apparatus.

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