JPH06327634A - Ophthalmological equipment - Google Patents

Abstract

PURPOSE:To prevent an ophthalmological equipment capable of photographing a corneal endothelial cell and measuring the thickness of the cornea by a single equipment and lightening the burden on both an examiner and examinee. CONSTITUTION:This equipment comprises: a lighting optical system 28 for irradiating the cornea C of an eye E to be examined with the lighting from a lighting sources 30, 32, an observation photographing optical system 29 for receiving the lighting reflected from the cornea C to observe and photograph the image on the cornea C; and an operation circuit for receiving the reflected light from the surface and the back of the cornea and for measuring the thickness of the cornea based on the distance between the two reflected lights.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ophthalmologic apparatus having both functions of photographing corneal endothelial cells of an eye to be examined and measuring corneal thickness.

[0002]

2. Description of the Related Art Conventionally, as a device having both functions of photographing corneal endothelial cells and measuring corneal thickness, a contact type device in which a cone lens is brought into contact with the corneal surface of an eye to be photographed and measured. Being developed.

[0003]

However, in the conventional radiographic measuring apparatus, a cone lens is brought into contact with the corneal surface of the eye to be photographed or measured, and therefore, the eye of the subject must be anesthetized with eye drops. In addition, the corneal surface may be damaged, and the corn lens needs to be disinfected in order to avoid the risk of infection, which is time-consuming and burdens both the examiner and the subject.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and it is possible to perform imaging of corneal endothelial cells and measurement of corneal thickness with a single device, and further, It is an object of the present invention to provide an ophthalmologic apparatus which imposes less burden on the examiner and the subject.

[0005]

In order to achieve the above object, the present invention provides an illumination optical system for obliquely irradiating an illumination light from an illumination light source toward a cornea of an eye to be inspected, and a reflected light from the eye to be inspected. It is characterized by comprising an observation and photographing optical system for receiving and observing and photographing the image of the cornea including the image of the corneal endothelial cells, and a measuring means for receiving the reflected light from the eye to be examined and measuring the thickness of the cornea. And

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the device for photographing corneal endothelial cells and measuring corneal thickness according to the present invention will be described below with reference to FIGS.

1 and 2 show an optical system of a corneal endothelial cell photographing and corneal thickness measuring device. The anterior ocular segment observation optical system 1 for observing the anterior ocular segment of the eye E includes a half mirror 2, an objective lens 3, a half mirror 4, an optical path switching mirror 5, and CC.
It is generally composed of a D (imaging device) 6, and O1 is its optical axis.

The optical path switching mirror 5 has a light-shielding surface 5a on one side and a total reflection surface 5b on the other side. When observing the anterior segment, the optical path switching mirror 5 is retracted from the optical path as shown by the chain double-dashed line in the figure.

The half mirror 2 includes an alignment index light projection optical system 8 and a fixation target light projection optical system 1 shown in FIG.
It is provided in order to guide the light flux from 4 to the subject's eye.

The alignment index light projection optical system 8 includes an alignment light source 9 which emits infrared light, a pinhole plate 10,
The pinhole plate 10 has a projection lens 11 and a half mirror 12 which are arranged so that their focal points coincide with each other. The alignment index light K emitted from the light source 9 and transmitted through the pinhole plate 10 is collimated by the projection lens 11 and reflected by the half mirror 2, and then, as shown in FIG. Bright spot image R at an intermediate position between O3 and
Are reflected by the surface T so as to form

The reflected light flux from the cornea C is reflected by the half mirror 2.
Is guided to the half mirror 4 via the objective lens 3 and is partially reflected by the half mirror 4 to be guided to the alignment detection sensor 4'as a light receiving means.
For example, a PSD (Posit
A sensor capable of detecting a position, such as an ion sensitive device) is used.

An alignment pattern projection optical system 21 is provided at a position facing the alignment detection sensor 4'with the half mirror 4 interposed therebetween. The alignment pattern projection optical system 21 includes an alignment pattern light source 22, an alignment pattern plate 23, and a projection lens 24.
It consists of An annular pattern is formed on the alignment pattern plate 23, and a part of the pattern-forming light beam that has passed through this pattern plate is reflected by the half mirror 4 and reaches the CCD 6.

On the other hand, the fixation target light projection optical system 14 comprises a fixation target light source 17 and a projection lens 11 for projecting the fixation target light emitted from the light source 17 onto the eye to be examined. In this example, the fixation target light source 17 is composed of a plurality of light emitting diodes 18, 18, ... Arranged in a radial pattern as shown in FIG. 4, and selectively turns on the light emitting diodes at any location. Thus, the line-of-sight direction of the subject can be changed.

The light source for the fixation target may be constructed by arranging light emitting diodes in a two-dimensional square array as shown in FIG. 5 (a), or as shown in FIG. 5 (b). May be arranged concentrically. Alternatively, as shown in FIG. 5C, a single light emitting diode may be movably provided.

An image of the anterior segment of the subject's eye E illuminated by the anterior segment illumination light source 7 is formed on the CCD 6 via the objective lens 3. The alignment index light transmitted through the half mirror 4 and the alignment pattern light from the alignment pattern projection optical system 21 reflected by the half mirror 4 also reach the CCD 6. Upon receiving the image signal from the CCD 6, the monitor device 25 receives the cornea C of the eye E to be inspected, the anterior segment image 26 including the pupil Pu, the annular pattern image 27 by the pattern light, and the alignment index light as shown in FIG. To form a bright spot image R '.

An illumination optical system 28 and an observation / photographing optical system 29 are provided on both sides of the anterior segment observation optical system 1 as shown in FIG. The illumination optical system 28 irradiates the cornea C of the eye E with an illumination light beam from an oblique direction. Illumination optical system 28
Is an illumination light source for observation 30 using a halogen lamp, a condenser lens 31, an infrared filter 31 ′, an illumination light source 32 for photographing using a xenon lamp, a condenser lens 33, a wavelength selection filter 33 ′, a dichroic mirror 37, Slit plate 34, light projecting lens 35, convex lens 3 for optical path length correction
5 ', and an aperture stop 38. An infrared LED may be used as the observation illumination light source 30 instead of the halogen lamp. In this case, the infrared filter 31 'can be omitted.

The infrared light emitted from the observation illumination light source 30, condensed by the condenser lens 31, and transmitted through the infrared filter 31 ′ is reflected by the dichroic mirror 37 and guided to the slit plate 34. At the time of photographing, the luminous flux emitted from the photographing illumination light source 32 is also condensed by the condenser lens 33, and is passed through the wavelength selection filter 33 ′ for increasing the contrast of the corneal endothelial cell image, and then the dichroic mirror 3 is formed.
7, and is guided to the slit plate 34. Slit 36
The light flux that has passed through is guided to the cornea C through the aperture stop 38 in the same direction as the light projecting lens 35 and the slit 36, and illuminates the cornea C so as to traverse inward from the surface T thereof.

The slit plate 34 is provided with a wide slit for photographing corneal endothelial cells which is elongated in the Y direction and a narrow slit 36 for measuring corneal thickness so that it can be selectively inserted into a light beam. It can be switched. Instead of the slit plate 34, a variable slit whose width can be continuously changed may be used.

In this embodiment, the convex lens 35 'is inserted in the optical path during observation using infrared light having a long wavelength.
When the visible light having a short wavelength is used, the visible light is removed from the optical path so that the light condensing position on the eye E side does not change regardless of which light source is used. Alternatively, a parallel plane plate or a concave lens may be used as the optical path length correction member. In this case, a plane parallel plate or the like may be inserted at the time of photographing and detached at the time of observation.

The observation / photographing optical system 29 includes an objective lens 40,
It is composed of a convex lens 40 'for correcting the optical path length, a half mirror 41, a mask 42, a relay lens 43, a mirror 44, a variable magnification lens 45, a focusing lens 46, and an optical path switching mirror 5. At the time of observing and photographing the corneal endothelial cells, the optical path switching mirror 5 is inserted into the optical path as shown by the solid line in FIG. The function of the convex lens 40 'is the same as that of the convex lens 35' in the illumination optical system 28, and the convex lens 40 'is inserted into or removed from the optical path according to the wavelength used.

FIG. 7 shows how the slit light flux L projected by the illumination optical system 28 is reflected by the cornea C. Part of the slit light flux L is first reflected on the corneal surface T which is the boundary surface between the air and the cornea C. The amount of reflected light flux L ′ from the corneal surface T is the largest. The amount of reflected light flux N ′ from the corneal endothelial cells N is relatively small, and the amount of reflected light flux M ′ from the corneal stroma M is the smallest.

The reflected light flux from the cornea C is the objective lens 40.
It is condensed by and is guided to the half mirror 41. The reflected light flux that has passed through the half mirror 41 forms an image once at the position of the mask 42. The mask 42 shields extra reflected light flux other than that for forming the corneal endothelial cell image. The reflected light flux that has passed through the mask 42 is reflected by the optical path switching mirror 5 via the relay lens 43, the mirror 44, the variable power lens 45, and the focusing lens 46, and forms an image of corneal endothelial cells on the CCD 6 at high magnification. .

The monitor device 25 has a corneal endothelial cell image 4
8 is displayed as shown in FIG. In FIG. 8, reference numeral 49 indicated by a broken line is an optical image formed by the reflected light beam L ′ from the corneal surface T if not shielded by the mask 42, and 50 is an optical image by the reflected light beam M ′ from the corneal substance M. . The shaded portion in FIG. 8 is a portion shielded from light by the mask 42.

The reflected light beam reflected by the half mirror 41 is guided to a line sensor 47 as a focus state detection sensor located at a position conjugate with the mask 42 at the image forming position. The line sensor 47 is shown in FIG. 9B in the cross-sectional direction of the cornea C.
And the intensity distribution of the reflected light flux is as shown in FIG. 9 (a). In FIG. 9A, a symbol U indicates a reflected light flux L ′ reflected on the surface T of the cornea C.
It is the peak part. Reference numeral V is a peak portion due to the reflected light flux N ′ reflected at the endothelial cell portion N of the cornea C. The peak portion U corresponds to the optical image 49, and the peak portion V corresponds to the optical image 48. Known means are used to detect the peak portion and the center of the peak portion.

The output of the line sensor 47 is input to the judgment circuit 47 'as shown in FIG. The determination circuit 47 'stores the signals of the peak portion U and the peak portion V as shown in FIG. 9 (a), and by performing arithmetic processing, the central address of the peak portion V of the reflected light from the corneal endothelial cell portion. While determining V ', this address V'is the predetermined address Q of the line sensor 47.
It is determined whether or not The device optical system has a peak part V
When the central address V'of the cell matches the predetermined address Q, the corneal endothelial cells are set to be in focus.

When measuring the corneal thickness, the cornea is illuminated with a narrow slit light for measuring the corneal thickness. At this time, the intensity distribution of the reflected light flux on the line sensor 47 has a narrower light amount distribution than that at the time of photographing the corneal endothelial cells in proportion to the slit width, as shown in FIG. 9C. By performing the same calculation process as described above, the center address β ′ of the peak portion β and the center address α ′ of the peak portion α are determined, and the center address β ′ of the peak portion β is the allowable range predetermined address Q of the line sensor 47. When entering, the interval W between the central address β ′ of the peak portion β and the central address α ′ of the peak portion α is calculated and stored.

At this time, narrowing the slit width reduces the widths of the peak portion β and the peak portion α, and reduces the light amount W ′ of the portion corresponding to the light image 50 by the reflected light flux from the corneal substance M. The accuracy of the central address (β ', α') and the interval W can be improved.

Here, at the interval W, at the cornea position shown in the schematic view of FIG. 10, the optical axis O2 of the illumination optical system 28 is the cornea C.
Corresponds to the distance from a point a intersecting the surface T of the above to an intersection d of a perpendicular line drawn to the optical axis O4 of the observation and photographing optical system 29.
Since the thickness of the cornea is the distance between the vertex P and the point b, the corneal thickness can be calculated by giving the optical axis angle θ of the apparatus, the image magnification at the position of the line sensor 47, and the surface curvature of the cornea. At this time, as the surface curvature of the cornea, the value of each cornea of the eye to be inspected may be entered, or the standard surface curvature may be used. Note that the above description ignores the difference in the refractive index between the cornea C and air, and in actuality, the corneal thickness is calculated by making a correction in consideration of the refractive index.

In order to improve the accuracy of corneal thickness measurement, the measurement may be performed a plurality of times and the average calculation may be performed, and the alignment allowable range may be set narrower than in the case of corneal endothelial cell imaging.

As described above, according to the apparatus of the embodiment, the output of the line sensor 47 as a focus detection sensor provided for observing and photographing corneal endothelial cells can also be used for the measurement of corneal thickness. As compared with providing separate optical systems, the configuration is simplified, and the increase in cost due to the increase in functions can be suppressed to a small level.

FIG. 11 is a block diagram showing the control system of the apparatus of the embodiment. In this example, the line sensor 47, the judgment circuit 47 ', the control circuit 51, and the arithmetic circuit 53 form a measuring unit that receives the reflected light from the eye to be inspected and measures the thickness of the cornea.

The determination circuit 47 'has a signal output from the line sensor 47 indicating the position of the device in the Z direction (front and back) with respect to the eye to be inspected, and the XY directions (up and down, left and right) output from the alignment detection sensor 4'. , And a selection signal from a mode selector switch 52 for switching between modes of photographing corneal endothelial cells and measuring corneal thickness.

The judgment circuit 47 'is composed of the mode changeover switch 5
According to the selection signal from 2, the slit plate 34 is selected so that the slit 36 having a width suitable for photographing and measuring of the slit plate 34 is selected.
And drive a signal to the control circuit 51. The slit plate 34 may be manually switched, and the mode may be selected according to this switching.

The control circuit 51 controls the CCD 6 and the arithmetic circuit 53 that performs arithmetic operations relating to the measurement of corneal thickness. The value of the corneal thickness obtained by the arithmetic circuit 53 is output by the printer 56 and C
It is synthesized with the output of CD6 and displayed on the monitor 25 in an overlapping manner with the image of corneal endothelial cells. The display result of the monitor 25 can be printed out by the printer 56.

Further, in order to specify which part of the cornea the photographed image of the corneal endothelium and the measured cornea correspond to, the light source 17 for the fixation target in which the fixation direction of the eye to be examined is selected is turned on. The positional information of the light emitting diode 18 that is operating can be printed out together with the image of the corneal endothelium image or the measurement result of the corneal thickness.

FIG. 12 is a flow chart showing control of photographing and measurement by the above apparatus. The judgment circuit 47 'is
The position detection value by the alignment detection sensor 4'enters the alignment allowable range in the vertical and horizontal directions, and the central address V'of the peak portion V of the reflected light from the corneal endothelial cell portion is the predetermined allowable range in the front-back direction of the line sensor 47. When entering Q, information about the selected mode and line sensor 4
And the output of 7 to the control circuit 51.

When the imaging of corneal endothelial cells is selected, the control circuit 51 turns off the light sources 7, 9, 17, 22 and turns off or dims the observation illumination light source 30 to correct the optical path length. The lenses 35 'and 40' are retracted from the optical path, the optical path switching mirror 5 is inserted in the optical path, the illumination light source 32 for photographing is turned on, and the CCD 6 is instructed to perform photographing. When the optical path switching mirror 5 is inserted into the optical path, the screen of the monitor device 25 is switched from the anterior ocular segment image screen (FIG. 6) to the corneal endothelial cell screen (FIG. 8).

When the measurement of the corneal thickness is selected by the mode changeover switch 52, the arithmetic circuit 53 measures and calculates the corneal thickness based on the output signal from the line sensor 47 after the completion of the alignment and focusing operations. To do.

Although the apparatus of the above-mentioned embodiment is configured to separately execute the image of corneal endothelial cells and the measurement of corneal thickness, the alignment in the XY and Z directions is completed when the image of corneal endothelial cells is taken. Light source (7, 9, 17, 22, 30)
Before the light is turned off or the light is dimmed, the output of the line sensor 47 may be stored to measure the corneal thickness.

In this case, as shown in FIG. 13, the slit structure is provided with a wavelength selection filter 58 for transmitting visible light and cutting infrared light on both sides of a narrow slit 57 for transmitting all luminous flux, and the alignment light is provided. The illumination light for observation and the illumination light for observation may pass through the narrow slit 57, and the illumination light for shooting may pass through the wide slit 60 divided by the non-transmissive portion 59.

[0041]

As described above, according to the present invention, the photographing of corneal endothelial cells and the measurement of corneal thickness can be performed by a single device, and the corneal endothelial cells can be recorded by a single alignment. Imaging and corneal thickness measurement can be performed continuously. Further, both imaging and measurement can be performed without contact with the eye to be inspected. Therefore, both the burden on the examiner and the subject can be reduced.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an optical system showing an anterior segment observation optical system, an illumination optical system, and an observation and photographing optical system of an ophthalmologic apparatus according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an alignment index light projection optical system and a fixation target projection optical system of the apparatus of the embodiment.

FIG. 3 is a diagram showing a reflection state of an alignment index light beam on the cornea.

FIG. 4 is an explanatory diagram showing a configuration of a fixation target light source.

FIG. 5 is an explanatory diagram showing a modified example of the light source for fixation target.

FIG. 6 is an explanatory diagram showing a display state of an anterior segment image.

FIG. 7 is a diagram showing a reflection state of a slit light beam on the cornea.

FIG. 8 is a diagram showing a display state of a corneal endothelial cell image.

FIG. 9 is a diagram showing a correspondence relationship between a corneal endothelial cell image and the amount of light received by a line sensor.

FIG. 10 is an enlarged view of the cornea for explaining the principle of obtaining the corneal thickness from the reflected light.

FIG. 11 is a block diagram showing a control system of the ophthalmologic apparatus according to the embodiment.

FIG. 12 is a flowchart showing control of the ophthalmologic apparatus according to the embodiment.

FIG. 13 is an explanatory diagram of slits suitable for use in a modified example of the embodiment.

[Explanation of symbols]

 1 ... Front eye observation optical system 2 ... Half mirror 3 ... Objective lens 6 ... CCD 7 ... Anterior eye illumination light source 8 ... Alignment index light projection optical system 9 ... Alignment light source 4 '... Alignment detection sensor 5 ... Optical path switching mirror 21 ... Alignment pattern projection optical system 28 ... Illumination optical system 29 ... Observation and photographing optical system 30 ... Observation illumination light source 32 ... Imaging illumination light source 36 ... Slit 37 ... Dichroic mirror 47 ... Line sensor 47 '... Judgment circuit

Claims (4)

[Claims] 1. An illumination optical system that obliquely irradiates illumination light from an illumination light source toward a cornea of an eye to be inspected, and light reflected from the eye to be inspected to receive the light of the cornea, including an image of corneal endothelium. An ophthalmologic apparatus comprising: an observation / photographing optical system for observing and photographing an image; and a measuring unit for receiving reflected light from the eye to be examined and measuring the thickness of the cornea. 2. The measurement means receives the reflected light emitted from the illumination optical system and reflected from the front and back surfaces of the cornea, and measures the thickness of the cornea based on the interval between the two reflected lights. The ophthalmologic apparatus according to claim 1, further comprising: 3. The observation / photographing optical system has a photoelectric conversion element composed of a device, an eye to be inspected, and a minute photoelectric element array for detecting an alignment state in the front-back direction, and the measuring means outputs from the photoelectric conversion element. The ophthalmologic apparatus according to claim 2, wherein the corneal thickness is measured based on a photoelectric conversion signal corresponding to the reflected light flux reflected from the front surface and the back surface of the cornea among the signals. 4. The optical axis of the illumination optical system and the optical axis of the observation / photographing optical system are arranged symmetrically with respect to the optical axis of the anterior segment observation optical system for observing the anterior segment of the subject's eye. The ophthalmologic apparatus according to claim 1, wherein: