JP2017148361A - Observation device and observation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an easy-to-use observation device which includes an autofocus mechanism for achieving automatic and highly accurate focusing on a corneal surface to thereby allow the conditions of the corneal surface including the lacrimal fluid layer to be observed without the need for using a mechanism to move the device.SOLUTION: The observation device includes an optical system for observing a corneal surface of an eye, comprising: an illumination unit for illuminating the eye; a focusing unit for focusing the optical system on a virtual image formed by illumination light of the illumination unit being reflected off the corneal surface, which serves as a convex mirror; and a control unit for controlling the focusing unit to move the focusing position of the optical system toward the optical system from a position at which the optical system is focused on the virtual image by a distance based on the curvature of cornea.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an observation apparatus and an observation method, and more particularly to an observation apparatus and an observation method for observing the state of the corneal surface.

  As an observation apparatus for noninvasively examining the state of the corneal surface, an optical inspection apparatus using a reflection image of light on the corneal surface is known.

  For example, in Patent Document 1, an image of a taken tear fluid layer is processed, and after the tear is opened, the time until the tear fluid layer is destroyed and the destruction region appears is measured, and the tear abnormality is quantitatively measured. An ophthalmic apparatus for measuring is disclosed.

JP 2011-156030 A

  In the optical ophthalmic apparatus described above, when observing the state of the tear fluid layer, the focus of the camera is fixed (it is a fixed optical system). It was necessary to move to an optimal position (focus on the corneal surface). Moreover, the cornea is transparent, and it has been difficult to focus on the cornea surface by an autofocus mechanism.

  The present invention has been made in view of the above-described points, and is equipped with an autofocus mechanism, and is configured to be able to focus on the cornea surface automatically and with high precision, thereby moving the apparatus. One object of the present invention is to provide a simple observation apparatus that can observe the surface of the cornea such as the state of the tear oil layer without the need for a tear.

The invention according to claim 1 is an observation apparatus including an optical system for observing the cornea surface of an eye,
From the illuminating unit that illuminates the eye, the focusing unit that focuses the optical system on the virtual image generated by the illumination light reflected from the corneal surface as a convex mirror, and the optical system from the position where the optical system is focused on the virtual image. And a control unit that controls the focusing unit to move the focusing position of the system to the optical system side by a distance based on the curvature of the cornea.

  The invention according to claim 9 is a method of observing the corneal surface of the eye with an optical system, the step of illuminating the eye with illumination light, and a virtual image generated by reflecting the illumination light as a convex mirror on the corneal surface A step of focusing the optical system and a step of controlling the focusing position of the optical system from the position where the optical system is focused on the virtual image to the optical system side by a distance based on the curvature of the cornea. It is characterized by.

1 is a block diagram illustrating a configuration of an observation apparatus 10 according to Example 1. FIG. 3 is a flowchart showing an observation procedure according to Example 1. FIG. 3 is a schematic diagram illustrating a contrast of a reflected image according to Example 1. 3 is a schematic diagram illustrating a positional relationship between a cornea surface and a reflected image according to Example 1. FIG. It is a figure explaining the virtual image produced | generated when the light emission surface of an illumination part inclines with respect to an optical axis. 6 is a block diagram illustrating a configuration of an observation apparatus 40 according to Example 2. FIG. It is a figure which shows an example of the shape of the reflected image 46 of the cornea based on Example 2. FIG. FIG. 10 is a block diagram illustrating a configuration of an observation apparatus 50 according to a third embodiment.

  Hereinafter, preferred embodiments of the present invention will be described in detail. In the following description and the accompanying drawings, substantially the same or equivalent parts are denoted by the same reference numerals.

  With reference to FIGS. 1-5, the observation apparatus 10 which concerns on Example 1 is demonstrated. FIG. 1 is a block diagram schematically showing the configuration of the observation apparatus 10. An eye (test eye) 30 that is an object to be observed by the observation apparatus 10 is schematically shown together with the observation apparatus 10. The eye 30 has a cornea 31 and an eyeball 32.

  The observation apparatus 10 includes an optical system 11, an illumination unit 17, a storage unit 28, and a processor 29. Let the optical axis of the optical system 11 be the optical axis X.

  The optical system 11 includes an imaging lens 13, a lens driving unit 14, an objective lens 15, and an image sensor 16. The imaging lens 13 forms an image of the light collected by the objective lens 15. The image sensor 16 converts the image formed by the imaging lens 13 into a digital signal.

  Further, the lens driving unit 14 drives the imaging lens 13 based on a signal from the processor 29. The lens driving unit 14 is, for example, an actuator that moves the imaging lens 13. The imaging lens 13 and the lens driving unit 14 constitute a focusing mechanism 12.

  The light emission surface 17a of the illumination part 17 has the shape (cone shape) of the side surface of a truncated cone. More specifically, the central axis of the light emitting surface 17 a of the illumination unit 17 (that is, the central axis of the truncated cone) is coaxial with the optical axis X of the optical system 11. Of the two openings corresponding to the top and bottom surfaces of the truncated cone, a large opening (bottom surface) is arranged toward the eye 30. The illumination light emitted from the light emitting surface 17a of the illumination unit 17 is applied to the cornea 31, and an image of the light emitting surface 17a is formed.

  The processor 29 is, for example, a CPU (Central Processing Unit) and performs arithmetic processing. The processor 29 includes a focus adjustment unit 22, a control unit 23, an image processing unit 24, and a display unit 27. The focusing mechanism 12 and the focusing adjustment unit 22 constitute a focusing unit.

  The focus adjustment unit 22 drives the focus mechanism 12 based on a signal from the image processing unit 24 to perform focus adjustment of the optical system 11.

  The control unit 23 performs movement control of the imaging lens 13. More specifically, after the focus adjustment unit 22 performs the focus adjustment, the imaging lens 13 is moved to control the optical system 11 so that the focus of the optical system 11 is on the surface of the cornea 31. For example, the moving distance of the imaging lens 13 is calculated based on the curvature of the cornea 31 and the imaging lens 13 is moved.

  The image processing unit 24 performs image processing on the image data from the image sensor 16 and generates image processing data. For example, data on the contrast and dimensions in the image is generated.

  The display unit 27 performs display processing such as generating display data for displaying an operation screen or an observation result on a display, for example.

  The storage unit 28 includes a storage device capable of erasing and writing data, such as an HDD (Hard Disk Drive) and a semiconductor memory. The storage unit 28 stores, for example, a program for executing focus adjustment and focus control, data used for lens driving, image data generated by observation, and the like.

  The optical system 11, the illumination unit 17, the storage unit 28, and the processor 29 are connected to each other by, for example, a transmission line (bus line) BL capable of bidirectional communication.

  FIG. 2 is a flowchart showing an observation method in the observation apparatus 10.

  First, in step S11, the illumination unit 17 irradiates the cornea 31 with illumination light from the light emitting surface 17a. The central axes of the eyeball 32 and the cornea 31 are aligned so as to be positioned on the optical axis X. The surface of the cornea 31 at this time is referred to as an observation surface.

  Subsequently, when focus adjustment (step S12) and focus control (step S13) for moving the focus position are executed, the state of the cornea surface can be observed (step S14). Steps S12 and S13 will be described in detail.

  In step S <b> 12, the focus adjustment unit 22 focuses the optical system 11 on the reflected image 33 formed by reflecting the illumination light by the cornea 31. Focusing (focus adjustment) is performed by moving the imaging lens 13 along the optical axis X and changing the position of the imaging lens 13 relative to the objective lens 15. The imaging lens 13 is moved by the focus adjustment unit 22 controlling the lens driving unit 14 based on the image processing result of the image processing unit 24. In other words, step S12 is a step of focusing by autofocus. The focus may be adjusted manually.

  Here, the surface (observed surface) of the cornea 31 which is a reflection surface on which the light of the illumination unit 17 is reflected has a convex mirror shape. The convex mirror generates a virtual image of an object placed in front of the convex mirror. Therefore, the reflected image 33 by the cornea 31 is a virtual image 33 generated when the illumination light of the illumination unit 17 is reflected by using the surface of the cornea 31 as a convex mirror. That is, step S12 is a step in which the focus adjustment unit 22 focuses the optical system 11 on the virtual image 33.

  The focus adjustment in step S12 is performed by a contrast method, for example. The imaging lens 13 is moved along the optical axis X so that the contrast of the virtual image 33 is maximized.

  FIG. 3 is a schematic diagram showing the contrast of the reflected image 33 of the illumination light. 31A indicates a bright area, and 31B indicates a dark area (iris). Reference numeral 31C denotes a boundary region between the bright region 31A and the dark region 31B. For clarity of illustration, hatching is shown except for the bright region 31A.

  The reflected image 33 of the illumination light (having the shape of the side surface of the truncated cone) of the illumination unit 17 is observed as a bright ring-shaped region 31A centering on the optical axis X. That is, since the illumination light emitting surface 17a has a truncated cone side surface shape, the illumination light reflection image 33 is a bright ring-shaped region 31A. On the other hand, the inner region of the ring-shaped region 31A is a dark circular region 31B and a boundary region C.

  Whether or not the reflected image (virtual image) 33 of the illumination light of the illumination unit 17 is focused (in focus) can be determined from the contrast between the region 31A and the region 31C. Specifically, for example, a position (focus position) where the contrast is maximized is determined by image analysis of an area 31D which is a boundary area between the area 31A and the area 31C, and focus adjustment is performed.

  When focus adjustment is made, the process proceeds to step S13. Step S13 will be described with reference to FIG. FIG. 4 is a cross-sectional view of the cornea 31 along the optical axis X. For clarity of illustration, the cornea 31 is shown as a solid line (ignoring thickness). 4 schematically shows the positional relationship and distance between the cornea 31, the position 35 of the reflected image (virtual image) 33 by the cornea 31, the cornea surface 36, and the position 37 of the illumination light. The distance between the position 37 of the illumination light and the corneal surface 36 is “a”, and the distance between the corneal surface 36 and the position 35 of the reflected image 33 is “b”. Further, the center of curvature of the cornea 31 is C and the radius of curvature is R.

  When focused on the position 35 of the reflected image 33, it is not focused on the corneal surface 36. Therefore, in order to enable observation of the corneal surface 36, the focal position of the optical system 11 is moved from the position 35 of the reflected image 33 to the optical system side along the optical axis X, that is, by a distance b in the direction of the corneal surface 36. Move.

  The distance b can be calculated based on the curvature of the cornea 31. Here, the following formula (1) is established from the imaging formula of the convex mirror.

例えば、曲率半径Ｒに、一般に日本人の角膜の曲率半径の平均値とされている７．８ｍｍを用いると、以下の式（２）が成立する。

For example, when the curvature radius R is 7.8 mm, which is generally the average value of the curvature radius of the Japanese cornea, the following equation (2) is established.

式（２）において、例えば距離ａを３０ｍｍとした場合、値ｂは３．４５ｍｍとなる。本実施例において、曲率半径Ｒは、予め格納部２７に格納された値を使用する。例えばデフォルト値としてＲ＝７．８ｍｍが設定されているが、任意の母集団について得られた角膜の曲率の平均値を採用することもできる。また、例えば、外部の装置によって実測された角膜の曲率半径の値を採用することができるように構成されていてもよい。

In the formula (2), for example, when the distance a is 30 mm, the value b is 3.45 mm. In the present embodiment, the curvature radius R uses a value stored in the storage unit 27 in advance. For example, R = 7.8 mm is set as a default value, but an average value of the curvature of the cornea obtained for an arbitrary population can also be adopted. For example, the value of the radius of curvature of the cornea actually measured by an external device may be adopted.

  In step S <b> 13, the control unit 23 calculates a value b corresponding to the distance a using the equation (2), and moves the focus position along the optical axis X based on the value b. That is, from the position 35 where the optical system 11 is focused on the reflected image (virtual image) 33 so that the focal position of the optical system 11 is the position of the corneal surface 36 (that is, the target focused position), The control unit 23 controls a focusing unit including the focusing adjustment unit 22 and the focusing mechanism 12 so that the focusing position is moved to the optical system 11 side by a distance b based on the curvature of the cornea.

  When the focus control in step S13 ends, the process proceeds to step S14. In step S14, the corneal surface such as the tear film is observed. Specifically, the acquired image is displayed, analyzed as necessary, and the data is stored. The observation of the corneal surface is performed by the processor 29 executing display, analysis, and storage of an image, for example. Moreover, it may be configured such that the observer can perform analysis and storage while viewing the displayed image.

  In the above description, the case where the light emitting surface 17a of the illumination unit 17 has a truncated cone side surface shape (cone shape) is described, but the present invention is not limited thereto. For example, the light emitting surface of the illumination unit 17 may be provided in a plane perpendicular to the optical axis X. Moreover, you may comprise the illumination part 17 so that the light emission surface of the illumination part 17 may form a predetermined illumination pattern. In this case, the cornea 31 forms a reflected image (virtual image) corresponding to the illumination pattern. Then, the focus adjustment of the optical system is performed so that the contrast of the reflected image is maximized, and the focus position is moved (focus control) from the focus position by a distance b based on the curvature of the cornea.

  In addition, the shape and arrangement of the light emitting surface of the illumination unit 17 will be described below. In the present embodiment, the light emitting surface 17a of the illuminating unit 17 has a truncated cone side surface shape, so that the light emitting surface 17a of the illuminating unit 17 is inclined with respect to the optical axis X. FIG. 5 is a cross-sectional view along the optical axis X of the cornea 31, and schematically shows the positional relationship between the reflected image (virtual image) 33 and the light emitting surface 17 a of the illumination unit 17. FIG. 5 shows a case where the light emitting surface 17 a of the illumination unit 17 is inclined with respect to the optical axis X.

  As described above, according to the observation apparatus 10 of the present embodiment, it is possible to focus on the cornea surface with high accuracy by adjusting the focus on the reflected image by the cornea and controlling the movement of the focus position. That is, it is possible to provide a simple observation device capable of focusing on the cornea surface and the tear fluid layer formed on the cornea surface automatically and with high accuracy. Further, it is possible to provide a simple observation apparatus that can observe the corneal surface such as the state of the tear oil layer without the need for a moving mechanism of the optical system of the apparatus.

  With reference to FIGS. 6 and 7, an observation apparatus 40 according to Example 2 will be described. FIG. 6 is a block diagram schematically illustrating the configuration of the observation apparatus 40 according to the second embodiment. The basic configuration is the same as that of the observation apparatus 10 of the first embodiment, but the configurations of the illumination unit 17 and the processor 29 are different. Specifically, an illumination unit 47 is provided instead of the illumination unit 17, and a processor 49 in which a curvature measuring unit 45 is added to the processor 29 is provided.

  More specifically, the light emitting surface 47a of the illumination unit 47 has a pattern shape, and generates illumination light having the pattern shape. The illumination unit 47 irradiates the eye 30 that is the observation object with illumination light having the pattern shape. For example, in FIG. 6, the illumination unit 47 has a frustoconical inner surface coaxial with the optical axis X, and has a light emitting surface 47 a in which a plurality of ring-shaped light emitting units are provided on the inner surface of the truncated cone. ing. Such a light emitting surface can be configured, for example, by covering the light emitting surface with a sheet having a pattern shape or the like.

  The illumination light that forms the illumination pattern from the illumination unit 47 is reflected by the surface of the cornea 31 as a convex mirror, thereby generating a reflected image (virtual image) 46 having a shape corresponding to the pattern shape.

  FIG. 7 shows the pattern shape of the reflected image 46 by the cornea 31 generated by the illumination unit 47. The region 47A corresponds to a bright portion of the reflected image 46, that is, a light irradiation portion, and has a plurality of ring patterns. The region 47B corresponds to a dark portion of the reflected image 46, that is, a portion where the light of the illumination unit 47 is not irradiated.

  The curvature measuring unit 45 calculates the curvature radius R of the cornea by measuring the dimension of the pattern shape of the reflected image 46. For example, as shown in FIG. 7, when the ring shape is a concentric pattern, measure the dimensions such as the width and spacing of the bright and dark parts of the ring pattern, and analyze the amount of change according to the curvature of the cornea By doing so, the curvature radius R of the cornea can be calculated from the spatial frequency and the distortion of the pattern shape. That is, the radius of curvature R of the cornea can be calculated from the actually measured value of the illumination pattern shape that differs for each surface to be observed (the cornea of the observer).

  In addition, the pattern shape (illumination pattern shape) of the light emission surface 47a of the illumination part 47 is a ring pattern, a hatching pattern, etc., for example, and it is preferable that the light emission surface is arrange | positioned concentrically with the optical axis X. FIG. .

  The control unit 23 moves the in-focus position along the optical axis X by a distance b based on the curvature of the cornea. That is, control is performed so that the focal position of the optical system 11 is moved from the position where the optical system 11 is focused on the reflected image 46 toward the corneal surface 36 by the distance b, that is, toward the optical system 11.

  According to the observation apparatus 40 of the second embodiment, by using the irradiation light having a pattern shape, it is possible to actually measure the curvature of the cornea of the eye, which is the observation object, based on the shape of the reflected image (virtual image) by the cornea. Can be automatically focused. Therefore, it is possible to focus on each cornea of a different person to be observed with high accuracy and automatically, and to provide a simple observation device.

  Moreover, it is not necessary to move the entire optical system of the apparatus, and a simple observation apparatus that can observe the corneal surface such as the state of the tear fluid layer can be provided.

  With reference to FIG. 8, the observation apparatus 50 which concerns on Example 3 is demonstrated. FIG. 8 is a block diagram schematically illustrating the configuration of the observation apparatus 50 according to the third embodiment.

  The basic configuration is the same as that of the observation apparatus 10 of the first embodiment, but a part of the configuration is different. Specifically, a half mirror 52 is provided between the imaging lens 13 and the objective lens 15 of the optical system 51, an illumination unit 57 is provided instead of the illumination unit 17, and the processor 59 is provided with a light source control unit 55.

  The half mirror 52 reflects the illumination light from the illumination unit 57 and introduces the illumination light into the optical system 51. The light reflected by the half mirror 52 is irradiated to the cornea 31 through the objective lens. The half mirror 52 reflects the cornea 31 as a convex mirror and transmits the light collected by the objective lens 15. The transmitted light is imaged by the imaging lens. For example, the central axis of the illumination light to the cornea can be on the optical axis X of the optical system 51.

  The illumination unit 57 may be an external light source disposed outside the observation apparatus 50, and an arbitrary light source can be used. For example, by using a projector, illumination light having a pattern shape can be irradiated, and the pattern shape can be easily changed without exchanging parts of the illumination unit 57. Further, it is possible to adjust the focusing accuracy according to the illumination pattern shape and its fine density.

  The light source control unit 55 performs control related to light irradiation of the illumination unit 57 such as an instruction to change the pattern irradiated by the projector.

  Focus adjustment and focus control are the same as in the above-described embodiment. That is, the focus adjustment unit 22 controls the lens driving unit 14 based on the image processing result of the image processing unit 24 and performs the focus adjustment of the optical system 51. Further, the control unit 23 moves the in-focus position of the optical system 51 from the position where the optical system 51 is focused on the reflected image (virtual image) 53 by the cornea toward the cornea surface by a distance b based on the curvature of the cornea. The focus adjustment unit 22 is controlled so as to be moved to.

  As described above, also in the observation device 50 according to the third embodiment, it is possible to focus on the cornea surface and the tear fluid layer formed on the cornea surface by autofocus.

  Furthermore, illumination light can be introduced along the optical axis of the optical system 51, and the illumination pattern shape and its fine density can be easily changed. Therefore, it is possible to provide an observation apparatus that can automatically focus with high accuracy.

10, 40, 50 Observation device 11, 51 Optical system 12 Focusing mechanism 13 Imaging lens 14 Lens drive unit 15 Objective lens 16 Imaging element 17, 47, 57 Illumination unit 22 Focus adjustment unit 23 Control unit 24 Image processing unit 27 Display unit 28 Storage unit 30 Eye 31 Cornea 32 Eyeball 45 Curvature measurement unit 52 Half mirror 55 Light source control unit

Claims (9)

An observation apparatus comprising an optical system for observing the corneal surface of an eye,
An illumination unit that illuminates the eye;
A focusing unit that focuses the optical system on a virtual image generated by reflecting the illumination light of the illumination unit as a convex mirror on the corneal surface;
A control unit that controls the focusing unit so that the focusing position of the optical system is moved to the optical system side by a distance based on the curvature of the cornea from the position at which the optical system is focused on the virtual image;
An observation apparatus comprising: A measurement unit for measuring the curvature of the cornea of the eye,
The observation apparatus according to claim 1, wherein the control unit moves a focus position of the optical system based on a curvature of the cornea measured by the measurement unit. The illumination unit irradiates illumination light that forms a predetermined illumination pattern,
The observation apparatus according to claim 2, wherein the measurement unit measures a curvature of the cornea of the eye based on a shape of the virtual image corresponding to the illumination pattern.   The observation apparatus according to claim 1, wherein the control unit moves a focus position of the optical system based on an average value of curvature of the cornea obtained for an arbitrary population.   The observation apparatus according to claim 1, wherein the focusing unit focuses the optical system based on a contrast of the virtual image of the illumination light.   The observation apparatus according to claim 1, wherein a light emitting surface of the illumination unit is arranged to have a side surface shape of a truncated cone coaxial with an optical axis of the optical system.   The observation apparatus according to claim 1, further comprising a half mirror that introduces illumination light from an external light source into the optical axis of the optical system.   The observation apparatus according to claim 7, wherein the illumination light from the external light source has an illumination pattern. A method of observing the corneal surface of an eye with an optical system,
Illuminating the eye with illumination light;
Focusing the optical system on a virtual image generated by reflecting the illumination light as a convex mirror on the corneal surface;
Controlling the optical system to move the focal position of the optical system to the optical system side by a distance based on the curvature of the cornea from the position where the optical system is focused on the virtual image;
An observation method characterized by comprising:

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