JP7074819B2 - Ophthalmic device and alignment method of ophthalmic device - Google Patents

Description

The present invention relates to an ophthalmic apparatus for acquiring data of an eye to be inspected and an alignment method in the ophthalmic apparatus.

The ophthalmologic apparatus includes an ophthalmologic measuring apparatus for measuring the characteristics of the eye to be inspected and an ophthalmologic photographing apparatus for obtaining an image of the eye to be inspected.

Ophthalmic measuring devices include ophthalmic refraction testing devices (refractometers, keratometers) that measure the refraction characteristics of the eye to be inspected, tonometers, and specular microscopes that obtain corneal characteristics (corneal film thickness, corneal endothelial cell density, etc.). , Hartmann-Wavefront analyzer that obtains error information of the eye to be inspected using a shack sensor and the like.
In addition, as an ophthalmologic imaging device, an optical coherence tomography that obtains a tomographic image using optical coherence tomography (OCT), a fundus camera that photographs the fundus, and laser scanning using a cofocal optical system are used. Examples thereof include a scanning laser ophthalmoscope (SLO) that obtains an image of the fundus of the eye.

In an ophthalmic examination using such a device, it is important to align the optical system with the eye to be inspected from the viewpoint of the accuracy and accuracy of the examination. Alignment generally includes an operation of aligning the optical axis of the eye to be inspected with the optical system (XY alignment) and an operation of adjusting the distance between the eye to be inspected and the optical system to a predetermined working distance (Z alignment). ..

Regarding such alignment, there are some that perform XY alignment and Z alignment based on the pupil image captured by the stereo camera (see Patent Document 1, Patent Document 2, and Patent Document 3). Alignment with this stereo camera has a wide alignment range and does not require manual alignment, and in most cases automatic alignment is possible.

Japanese Unexamined Patent Publication No. 2013-248376 Japanese Unexamined Patent Publication No. 2014-113385 Japanese Unexamined Patent Publication No. 2014-124370

However, in the alignment using a conventional stereo camera, since the reference position of the device and the distance of the pupil are used as a reference, the position of the apex of the cornea cannot be determined due to individual differences in the depth of the anterior chamber. In Patent Document 3, a method of correcting the depth position information of the pupil image using the corneal refractive power is studied, but in order to obtain the corneal refractive power, a mechanism for measuring the curvature of the cornea is separately provided. There is a need.

Therefore, as a means for aligning the working distance, the stereo camera method cannot be used in a device that requires alignment with the apex of the cornea because it is affected by individual differences such as the depth of the anterior chamber and the curvature of the cornea.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an ophthalmic apparatus capable of quickly and accurately aligning a measurement optical system with the apex of the cornea of an eye to be inspected, and an alignment method for the ophthalmic apparatus. And.

The invention according to claim 1 that solves the above problems is a device main body having an infrared light irradiation system that irradiates an eye to be inspected with infrared light and an infrared light detection system that detects the infrared light from the eye to be inspected. The support portion that supports the position of the subject's face and the device main body and the support portion are relatively moved to align the axis of the device main body with respect to the eye to be inspected, and the device main body is moved to the device body. In an ophthalmology device provided with a drive unit that adjusts the distance to the eye to be inspected, the eye to be inspected is substantially photographed from different directions, and the imaging magnification of one imaging device is larger than the imaging magnification of the other imaging device. An image of the eye to be inspected is acquired from two imaging images of the eye to be inspected by the infrared light taken by the two imaging devices and the position of the eye to be inspected is detected from the image of the eye to be inspected. A second alignment that acquires a scattered image of the cornea of the eye to be inspected by visible light taken by at least one of the first alignment detection unit and the two imaging devices, and detects the apex of the cornea based on the scattered image. Based on the detection results of the detection unit and the first alignment detection unit, the drive unit is controlled to align the main body of the device with respect to the eye to be inspected, and based on the detection results of the second alignment detection unit. The ophthalmic apparatus is characterized by having a drive control unit that controls the drive unit to adjust the distance of the main body of the device to the eye to be inspected, or to perform alignment and distance adjustment.

Similarly, the invention according to claim 2 is a device main body that irradiates an eye to be inspected with infrared light and detects the infrared light from the eye to be inspected, a support portion that supports the position of the face of the subject, and the device. In an ophthalmic device including a drive unit that relatively moves the main body and the support portion, the device main body and the support portion are relatively moved to align the device main body with the eye to be inspected, and An alignment method for an ophthalmic device that adjusts the distance to the eye to be inspected, in which the cornea of the eye to be inspected is irradiated with infrared rays from two different directions, and one of the imaging magnifications is larger than the other imaging magnifications. A step of detecting a Pulkin-e image in the eye to be inspected by photographing substantially simultaneously, a step of aligning the main body of the apparatus with the eye to be inspected based on the position of the image of the Pulkin-e , and a visible irradiation of the eye to be inspected. Based on the step of detecting the scattered image in the cornea by light and the apex of the cornea of the eye to be inspected detected based on the scattered image, the apparatus main body is distance-aligned or aligned with respect to the eye to be inspected. It is an alignment method of an optometry apparatus, which comprises a step of adjusting a distance and a step of adjusting the distance.

According to the present invention, the device body can be quickly and accurately aligned with the apex of the cornea of the eye to be inspected.

That is, according to the ophthalmic apparatus according to claim 1, the eye to be inspected is photographed by two or more imaging devices in which the imaging magnification of at least one imaging device is larger than the imaging magnification of the other imaging device, and the captured infrared light is taken. An image of the purkine of the eye to be inspected was obtained from two or more images taken of the eye to be inspected by, and the main body of the device was aligned with the eye to be inspected based on this image of the purkine, and then at least one of the two imaging devices was photographed. Since the corneal position is detected based on the scattered image in the cornea of the eye to be inspected by visible light , and the distance is adjusted, or the distance is adjusted and the alignment is performed with respect to the eye to be inspected of the main body of the device, the ophthalmologic device directly detects the eye to be inspected. It can be aligned based on the apex of the cornea, without the need to consider differences in the subject's anterior chamber depth or corneal curvature.

Further, according to the alignment method of the ophthalmic apparatus according to claim 2, the cornea of the eye to be inspected is irradiated with infrared rays from two different directions, and one of the corneas is substantially larger than the other. The image of Purkinje in the eye to be inspected is detected at the same time, the main body of the device is aligned with the eye to be inspected based on the position of the image of Purkine, and the scattered image in the cornea by the visible light irradiated to the eye to be inspected is detected and disturbed. Based on the apex of the cornea of the eye to be inspected detected based on the image, the apparatus main body adjusts the distance to the eye to be inspected, or performs alignment and distance adjustment. Therefore, in the alignment of the ophthalmic appliance, the alignment can be performed based on the apex of the cornea of the eye to be directly detected, and it is not necessary to consider the difference in the anterior chamber depth and the corneal curvature of the subject.

The appearance of the non-contact tonometer according to the embodiment of the present invention is shown, (a) is a front view, and (b) is a side view showing a state of use. It is a schematic diagram which shows the internal structure of the non-contact type tonometer, (a) is a side view, (b) is a plan view. It is a block diagram which shows the control system of the non-contact type tonometer ophthalmic apparatus. It is a flowchart which shows the schematic operation procedure of the non-contact type tonometer. It is a schematic diagram which shows the relationship between the position of the eye under test with respect to the photographing apparatus in the non-contact type tonometer and the photographed image. It is a schematic diagram which shows the relationship between the position of the eye under test with respect to the photographing apparatus in the non-contact type tonometer and the photographed image. It is a schematic diagram which shows the relationship between the position of the eye under test with respect to the photographing apparatus in the non-contact type tonometer and the photographed image. The photographed image acquired by the non-contact tonometer is described, (a) is a schematic diagram explaining a Purkinje image, and (b) is a schematic diagram explaining a scattering image by a cornea. It is a flowchart which shows the basic operation procedure of the non-contact type tonometer. It is a schematic diagram explaining the non-contact type tonometer which concerns on 2nd Embodiment of this invention.

The ophthalmologic device according to the embodiment for carrying out the present invention and the alignment method of the ophthalmology device will be described. The present invention can be applied to any ophthalmologic measuring device, any ophthalmologic imaging device, or any multifunction device. That is, the present invention can be applied to a reflex meter, a keratometer, a specular microscope, a tonometer, etc. as an ophthalmic measuring device. Further, the present invention can be applied to an OCT (optical coherence tomography) device, a fundus camera, an SLO (scanning laser ophthalmoscope) and the like as an ophthalmologic imaging device.

Hereinafter, a non-contact tonometer will be described as an example of the ophthalmic apparatus according to the embodiment.

<Rough configuration of non-contact tonometer>
FIG. 1 shows the appearance of a non-contact tonometer according to an embodiment of the present invention, (a) is a front view, and (b) is a side view showing a usage state. The non-contact tonometer S includes a support portion 1, a device base 2, a gantry 3, and a device main body 4.

The support portion 1 is arranged on the device base 2 and supports the face HB of the subject. The device base 2 has a support portion 1. The device base 2 is arranged on the installation base T, and the gantry 3 is arranged on the upper portion. The gantry 3 is provided so as to be movable in the front-rear direction and the left-right direction with respect to the device base 2. The front-back direction (direction along the optical axis of the non-contact tonometer S) is the Z direction, the left-right direction perpendicular to the optical axis is the X direction, and the vertical direction is the Y direction.

The device main body 4 is provided on the upper part of the gantry 3, and is relatively moved in the Z direction, the X direction, and the Y direction with respect to the gantry 3 by the operation of the internal drive unit 50. The apparatus main body 4 may have a structure that does not move independently with respect to the gantry 3 but moves integrally in the Z, X, and Y directions.

The gantry 3 is provided with an operation knob 5 having a measurement button 5a, a monitor 6 and the like. The operation knob 5 is operated by an inspector, whereby the gantry 3 is moved back and forth, left, right, up and down. In this example, the device main body 4 moves back and forth and left and right by tilting the operation knob back and forth and left and right, and the device main body 4 moves up and down by rotating the knob itself around the axis of the knob. Further, on the front surface of the apparatus main body 4, an airflow blowing nozzle 8 is provided through an anterior eye portion window glass 12 (see FIG. 2) so as to face the subject's eye E to be inspected. Further, the operation knob 5 may be configured to perform its function by using the touch panel of the monitor 6, an external mouse, or the like.

<Internal configuration of non-contact tonometer>
2A and 2B are schematic views showing the internal configuration of the non-contact tonometer, where FIG. 2A is a side view and FIG. 2B is a plan view. Inside the main body 4, an air chamber 11, an intraocular pressure measuring system 10, an infrared light irradiation system 20, and a visible light irradiation system 30, which are infrared light detection systems, are arranged. In the present embodiment, two front-facing cameras 41 and 42 are arranged on the device main body 4 as two photographing devices that sandwich the axis O1 in the Y direction. The front-face cameras 41 and 42 are provided with an infrared light source that irradiates infrared light toward the eye E to be inspected. The front-face cameras 41 and 42 capture the eye to be inspected from different directions substantially simultaneously. Here, "substantially at the same time" means that in the shooting with the front-face cameras 41 and 42, the deviation of the shooting timing to the extent that the eye movement can be ignored is allowed. Thereby, two or more images when the eye to be inspected E are in the same position can be acquired by the anterior eye camera.

Air is sent out from the air injection device 60 to the air chamber 11, and the sent out air is ejected from the airflow blowing nozzle 8 toward the eye E to be inspected. In the figure, reference numeral 12 indicates front eye glass, and reference numerals 13 and 14 indicate chamber glass. An air injection device 60 (see FIG. 3) is connected to the air chamber 11. The air injection device 60 compresses the air in the cylinder with a piston driven by a solenoid, and sends the compressed air to the air chamber 11.

Behind the air chamber 11, the optical axes of the tonometry measurement system 10, the infrared light irradiation system 20, and the visible light irradiation system 30 are arranged, and the tonometry measurement system 10, the infrared light irradiation system 20, and the visible light irradiation system 30 are arranged. The optical axis of is arranged in the airflow blowing nozzle 8. Further, a chamber window glass 14 is arranged in the air chamber 11, and the axis O1 of the tonometer pressure measuring system 10, the infrared light irradiation system 20 and the visible light irradiation system 30 penetrates through the chamber window glass 14. The chamber window glass 14 is tilted at a predetermined angle with respect to the axis O1 in order to eliminate the influence of light reflection.

<Optical system of non-contact tonometer>
As shown in FIG. 2A, the intraocular pressure measuring system 10 includes a first dichroic mirror 15, an imaging lens 16, a flattening sensor 17 composed of an infrared sensor, and a pinhole 18. Further, the infrared light irradiation system 20 includes an infrared light source 21 and a diaphragm 22. Further, the visible light irradiation system 30 includes visible light, for example, a blue visible light source 31 and a diaphragm 32. The infrared light irradiation system 20 and the visible light irradiation system 30 are coupled by a second dichroic mirror 24, are made into parallel light by a collimator lens 25, are guided to the first dichroic mirror 15, and blow an airflow nozzle 8 from the air chamber 11. After that, the subject E is irradiated.

In the present embodiment, the infrared light source 21 of the infrared light irradiation system 20 irradiates the eye E to be inspected with infrared light having a diameter of about 3 mm. The flattening sensor 17 detects the reflected light from the eye E to be inspected. When air is ejected from the airflow blowing nozzle 8 to the eye E to be inspected, the intraocular pressure is measured by measuring the change in the amount of reflected light based on the change in the corneal shape detected by the inflating sensor 17. In the present embodiment, the infrared light irradiation system 20 is used for measuring the intraocular pressure, and the eye E irradiated with the infrared light from the infrared light irradiation system 20 is captured by the front-facing cameras 41 and 42. Take a picture and use it for alignment of the non-contact tonometer S. Therefore, the brightness of the infrared light source 21 can be changed.

In the infrared light irradiation system 20, the infrared light from the infrared light source 21 passes through the diaphragm 22 and is reflected by the second dichroic mirror 24 to be a parallel light flux by the collimator lens 25. Then, it is reflected by the first dichroic mirror 15 and passes through the inside of the chamber window glass 14 and the airflow blowing nozzle 8 to illuminate the cornea of the eye E to be inspected. The infrared light irradiation system 20 and the visible light irradiation system 30 are combined coaxially with the second dichroic mirror 24 and irradiated to the eye E to be inspected.

The second dichroic mirror 24 transmits the wavelength in the visible light region from the visible light irradiation system 30 and reflects the wavelength in the infrared light region from the infrared light irradiation system 20. The second dichroic mirror 24 is formed with a dielectric multilayer film having the above-mentioned characteristics. The first dichroic mirror 15 has a characteristic of substantially reflecting wavelengths in the visible light region, partially transmitting wavelengths in the infrared region, and partially reflecting wavelengths in the infrared region. The second dichroic mirror 24 is a multilayer mirror, and generally has a transmittance of 50% and a reflectance of 50%, but may be configured to have a low transmittance and a high reflectance.

The infrared light reflected by the cornea of the eye E to be inspected passes through the inside of the airflow blowing nozzle 8, the chamber window glass 14, the first dichroic mirror 15, and passes through the imaging lens 16 and the pinhole 18, and the flattening sensor 17 To. The flattening sensor 17 detects a change in the amount of infrared light reflected from the cornea and transmitted through the pinhole 18. As a result, the intraocular pressure of the eye E to be inspected is measured.

That is, the cornea becomes flat and recessed due to the pressure of the injected air. The pinhole 18 is arranged so as to be conjugate with the light source by the imaging lens when the cornea becomes flat. Therefore, when the cornea changes from a convex surface to a flat surface and a concave surface, the maximum amount of light passes through the pinhole 18 and is incident on the flattening sensor 17. Therefore, it is determined that the cornea becomes flat when the amount of light received by the flattening sensor 17 becomes maximum from the start of air injection. Here, a pressure gauge for detecting the internal pressure of the air chamber 11 is arranged in the air chamber 11, and the pressure value detected when the amount of light is maximized (when the cornea becomes flat) is used as the intraocular pressure value. Be measured.

The visible light irradiation system 30 irradiates visible light from the visible light source 31 as fixed visual light that serves as a fixed collimation of the eye E to be inspected, and also obtains a scattered light image for detecting the apex position of the corneal membrane. Irradiate as. In the present embodiment, visible light is irradiated in a narrower range than the above-mentioned infrared light, the visible light source 31 is blue in consideration of the light scattering characteristics of the internal structure of the corneal membrane, and the brightness of the visible light source 31 can be changed. There is. The brightness of the visible light source 31 is increased when the scattered light is acquired than when it is used as the fixative light. The color of the visible light source 31 is not limited to blue, and green or the like can be used, but blue having a short wavelength is preferable because of the scattering characteristics of the internal structure of the cornea.

The subject fixes the line of sight to the measurement optical axis by fixing the image of the visible light source 31 that forms an image at substantially infinity. The diaphragm can be illuminated by the visible light source 31 and used as a secondary light source.

<Control system for non-contact tonometer>
Next, the control system of the non-contact tonometer S according to the embodiment will be described. FIG. 3 is a block diagram showing a control system of the non-contact tonometer ophthalmic apparatus. In addition to the above-mentioned first dichroic mirror 15, flattening sensor 17, second dichroic mirror 24, front-facing cameras 41 and 42, the device main body 4 includes an infrared light source 21, a visible light source 31, a drive unit 50, and an air injection device. 60 are arranged.

Further, a control unit 70 is connected to the device main body 4. The control unit 70 includes a first alignment detection unit 71, a second alignment detection unit 72, a drive control unit 73, an intraocular pressure measurement control unit 74, and a light source lighting control unit 75.

The control unit 70 is configured as a computer equipped with a CPU (Central Processing Unit) as a control means, a ROM (Read Only Memory) and a RAM (Random Access Memory) as a main storage device, and an HDD (Hard Disc Drive) as an auxiliary storage device. can. The program stored in the ROM by the CPU is used as the expansion area of the RAM to realize the functions of the above-mentioned parts.

In the first alignment, the first alignment detection unit 71 is located at the position of the eye E to be inspected E with respect to the device main body 4, that is, the up / down / left / right positions (X, Y) and the front-back position based on the Purkinje images acquired by the front-facing cameras 41 and 42. (Z) is detected. The Purkinje image is detected by processing the image data from the front-face cameras 41 and 42 by noise removal, binarization, contour detection, center of gravity detection, and the like.
In the second alignment, the second alignment detection unit 72 detects the front end position of the cornea based on the scattered image inside the cornea acquired by the frontal cameras 41 and 42. The detection of the apex of the cornea from the scattered image is performed by performing various processes such as noise removal, binarization, and contour detection on the image data from the front-face cameras 41 and 42.
In the first alignment, the drive control unit 73 drives the drive unit 50 based on the detection result of the first alignment detection unit 71 to perform positioning in the XY direction and distance adjustment in the Z direction. Further, in the second alignment, the drive control unit 73 drives the drive unit 50 based on the detection result of the second alignment detection unit 72 to adjust the distance in the Z direction.

<Approximate operation of non-contact tonometer S>
FIG. 4 is a flowchart showing the basic operation procedure of the non-contact tonometer. In order to measure the intraocular pressure of the subject with the non-contact tonometer S according to the present embodiment, the subject is first positioned on the support portion 1 (step S1), and then the first alignment (step S2) and the second alignment are performed. (Step S3), the tip of the airflow blowing nozzle 8 is aligned with the eye E to be inspected, and the distance is adjusted with respect to the apex of the cornea. Then, after the alignment is completed, the intraocular pressure is measured (step S4).

In the non-contact tonometer S according to the present embodiment, in the first alignment, the frontal cameras 41 and 42 that capture the eye E to be examined from different directions capture the Pulkiner image by the infrared light from the infrared light irradiation system 20. Then, a rough alignment is performed in the XYZ direction based on the captured Pulkinje image. After the completion of the first alignment, the apparatus main body 4 is retracted by a specified amount, and then the scattered light inside the cornea of the visible light from the visible light irradiation system 30 is imaged by the front-facing cameras 41 and 42, and Z is based on this scattered image. The second alignment is performed to adjust the distance in the direction.

Here, the Purkinje image is a reflected image obtained by reflecting the projected light on the cornea, the crystalline lens, or the like. As shown in FIG. 8A, the Purkinje image obtained by irradiating the cornea with a parallel light beam and reflecting on the surface of the cornea is a virtual image observed at a position ½ of the radius of curvature r of the cornea from the apex of the cornea. The image is acquired by the frontal cameras 41 and 42. The Purkinje image is a general term for images generated by reflection on the front and back surfaces of the cornea and the front and back surfaces of the crystalline lens. Strictly speaking, the Purkinje first image, second image, third image, and fourth image from the cornea surface side. It is called a statue. The Purkinje image used in the embodiment is the first Purkinje image due to surface reflection of the cornea.

In the present embodiment, the amount of retreat of the apparatus main body 4 before the first alignment is set to 1/2 of the average radius of curvature r of the cornea. The radius of curvature r of the average cornea can be 8 mm. The apparatus main body 4 is arranged at a position retracted by 4 mm from the position determined in the first alignment, and is switched to the second alignment. Here, the alignment in the XY direction is performed exclusively by the first alignment.
Here, a method of retreating by a certain amount after adjusting the distance to the Purkinje image in the first alignment was shown, but if the first alignment is performed in advance at a position where the retreat is a certain amount, after approaching the eye to be inspected once, The movement of retreating is eliminated, the alignment time is shortened, and the discomfort and the risk of contact due to the nozzle tip approaching the eye to be inspected can be avoided.

Here, in the first alignment based on the Purkinje image, since the image formation position of the Purkinje image differs depending on the curvature of the cornea, it is not possible to accurately match the distance to the apex of the cornea of the eye E to be examined for different subjects. .. This is because there are individual differences in the curvature of the cornea of humans. That is, the radius of curvature of the cornea is distributed in the range of about r7 to 9 mm, and in the case of the r7 mm cornea, the apex of the cornea is 3.5 mm in front of the reflected image position, and in the case of r9 mm, it is 4.5 mm in front. Will be. Therefore, it is expected that the apex position of the cornea will have an error of 1 mm only by the first alignment based on the Purkinje image under the condition that the curvature of the cornea is unknown. Since it is desirable that the alignment tolerance of a general non-contact tonometer is ± 0.5 mm or less, sufficient alignment cannot be achieved.

Hereinafter, the outline of the first alignment by the first alignment detection unit 71 and the second alignment by the second alignment detection unit 72 will be described.
<1st alignment>
In the first alignment, the first alignment detection unit 71 lights the infrared light source 21 of the infrared light irradiation system 20 by the light source lighting control unit 75. In the present embodiment, the infrared light irradiation system 20 is commonly used for the first alignment and the intraocular pressure measurement, and the brightness of the infrared light source 21 is adjusted to an appropriate value in each process. It should be noted that different illumination optical systems can be used in each process.

When the infrared light from the infrared light irradiation system 20 enters the cornea, a virtual image (Purkinje image) is generated at the r / 2 position of the cornea. In this example, this Purkinje image is imaged by the frontal cameras 41 and 42, and the airflow blowing nozzle 8 of the apparatus main body 4 and the eye to be inspected are examined based on the positional relationship between the two Purkinje images obtained by the frontal cameras 41 and 42, respectively. The relative position of the Purkinje image of E is detected, and the apparatus main body 4 is moved in the XYZ direction by the drive unit 50 to perform the first alignment. However, since this first alignment is performed on the Purkinje image, the distance between the apex position of the cornea and the tip of the airflow blowing nozzle 8 is not always appropriate.

Here, FIGS. 5, 6, and 7 show the relationship between the position of the eye E to be inspected with respect to the device main body 4 and the position of the Purkinje image acquired by the frontal cameras 41 and 42. It is a schematic diagram which shows the relationship between the position of the eye to be inspected with respect to an apparatus and a photographed image.

First, the distance between the eye E to be inspected and the tip of the airflow blowing nozzle 8 will be described with reference to FIG. The optical axes of the front-face cameras 41 and 42 are arranged so as to intersect at appropriate positions for alignment.
As shown in (a) in the figure (A), when the eye E to be inspected is properly positioned with respect to the device main body 4, that is, properly aligned in the XY direction and at an appropriate distance in the Z direction. As shown in FIG. 6B, the Pulkinje image P acquired by the frontal cameras 41 and 42 is located at the center of each image.

On the other hand, when the eye E to be inspected is close to the device main body 4 as shown in FIG. Each image of the Purkinje image P is located outside the central position.

Further, as shown in (a) in the figure (C), when the eye E to be inspected is far from the device main body 4, it is acquired by the front-face cameras 41 and 42 as shown in the figure (b). It is located inside the center position of each image of the Purkinje image.

Next, a case where the eye E to be inspected is displaced in the X and Y directions will be described with reference to FIG. In the figure (A), as shown in (a), it is assumed that the eye E to be inspected is properly positioned with respect to the device main body 4, that is, properly aligned in the XY direction and at an appropriate distance in the Z direction. As shown in FIG. 6B, the Purkinje image P acquired by the front-face cameras 41 and 42 is located at the center of each image.

On the other hand, when the eye E to be inspected is displaced in the X direction with respect to the device main body 4 as shown in FIG. The Pulkinje image P acquired in 41 and 42 is positioned so as to be displaced in the same lateral direction from the center position of each image image.

Further, in FIG. 3C, when the eye E to be inspected is displaced in the Y direction with respect to the device main body 4 as shown in FIG. It is positioned so as to be offset in the same vertical direction from the center position of each image of the Purkinye image acquired by the cameras 41 and 42.

It should be noted that the movement in the X direction and the movement in the Z direction cannot be distinguished from each other only by the image of one front camera. From the aligned state shown in FIG. 7 (A), the state in which the eye E to be inspected shown in FIG. 7 (B) approaches the device main body 4 and the state in which the eye E to be inspected shown in FIG. 7 (C) is moved in the X direction. Is the same in the images ((B) (b), (C) (b) in the same figure) acquired by one of the frontal cameras 42. The image acquired by the other front-facing camera 41 ((B) (a), (C) (a) in the same figure) can be combined and determined to determine in which direction the image is moving for the first time. The optical axes of the front-face cameras 41 and 42 do not necessarily have to intersect at an appropriate position for alignment, and may be in any direction. In this case, calibration is performed for the position between the cameras and the angle of the optical axis, and the position and the amount of movement of the image on the camera are corrected.

<Second alignment>
Next, the second alignment by the second alignment detection unit 72 will be described. To perform the second alignment, the second alignment detection unit 72 turns off the infrared light source 21 of the infrared light irradiation system 20 by the light source lighting control unit 75, and turns on the visible light source 31 of the visible light irradiation system 30. In this example, the visible light irradiation system 30 is shared with the fixative, and the visible light source 31 is already lit for the fixative, so the brightness is adjusted. The optical system for fixation and the optical system for second alignment can be separated.

As shown in FIGS. 8B and 8A, the light flux LB of visible light from the visible light irradiation system 30 enters the cornea C of the eye E to be inspected and passes through the cornea C. At this time, a part of the luminous flux LB is scattered by the tissue inside the cornea C, and this scattered light is received and observed by the frontal camera 42. The scattered light image 82 by the cornea C appears in the image 81 acquired by the front-face camera 42. As a result, the position of the captured scattered light image, particularly the position of the apex of the cornea, is detected. Since this scattered light is darker than the Purkinje image, the gain of the front-facing camera 42 is increased.

In the second alignment, one of the front-facing cameras 41 and 42 used in the first alignment, for example, the front-facing camera 42 is used. It should be noted that the imaging characteristics such as the magnification and the shooting angle of the front-face camera 42 to be used may be different as long as they are known.

Here, the light emitted by the visible light source 31 of the visible light irradiation system 30 is more likely to be scattered by the cornea as the wavelength is shorter. Therefore, it is desirable that the visible light source 31 is a blue light source. The front-face cameras 41 and 42 are first aligned in front of the front-face cameras 41 and 42 so that indoor illumination light and the like enter the camera and become ghosts and flares, which do not affect the detection of the Purkinje image and the scattered light image. It is desirable to install a transmission filter that transmits only the vicinity of the wavelength of infrared light used for the camera and the vicinity of the specific wavelength of visible light (for example, blue) used in the second alignment, and reflects and absorbs other wavelengths and does not transmit. ..

At least two front-facing cameras are required to detect the alignment state of XYZ in three directions. However, when the XY alignment, which is not affected by the curvature of the cornea, is completed in the first alignment and only the Z adjustment is performed in the second alignment, only one frontal camera may be used.

It should be noted that one of the two front-face cameras 41 and 42, for example, the front-face camera 41 may be arranged at an angle coincided with the axis O1 measurement optical axis. At least one or more images of the anterior eye portion taken by the frontal cameras 41 and 42 are displayed on the screen of the monitor 6, and the measurer can observe the state of the eye to be inspected.

When performing alignment by manual operation, the measurer can perform alignment based on this image. The image may be an image as it is acquired from one camera, or an image processed as seen from the front in almost real time. When manually aligning, it is desirable to arrange an infrared light source that illuminates the anterior segment of the eye so that the image of the anterior segment can be observed on the monitor in the vicinity of the frontal cameras 41 and 42.
Further, when the alignment is performed by manual operation, the alignment mark which is the reference of the alignment and the display showing the alignment deviation in the anteroposterior direction are superimposed on the image of the anterior eye portion and displayed.

<Basic operation procedure of non-contact tonometer>
Hereinafter, the details of the procedure for measuring the intraocular pressure will be described. FIG. 9 is a flowchart showing the operation procedure of the non-contact tonometer. First, in the non-contact tonometer S, the light source lighting control unit 75 of the control unit 70 lights the visible light source 31 of the non-contact tonometer S and irradiates the eye E to be inspected with fixative light (step ST1). .. Next, the light source lighting control unit 75 turns on the infrared light source 21 and illuminates the eye E to be inspected with infrared light (step ST2). As a result, the Purkinje image of the eye E to be inspected is imaged by the front-face cameras 41 and 42 and acquired by the first alignment detection unit 71.

Based on this, the first alignment detection unit 71 drives the drive unit 50 to perform the first alignment. In the present embodiment, the XY spot (Purkinje image) of the eye E to be inspected is detected in order to perform the first alignment (step ST3). When an XY spot is detected (YES in step ST4), alignment in the XY direction and distance alignment in the Z direction (XYZ alignment) are performed (steps ST10 to ST12).

When the XY spot cannot be detected (NO in step ST4), the first alignment detection unit 71 searches for the pupil from the images acquired by the front-face cameras 41 and 42 (step ST5). First, the pupil is detected, and then the Purkinje image is detected. When the pupil is detected (YES in step ST6), the first alignment detection unit 71 calculates the center position of the pupil (step ST7), and the first alignment detection unit 71 performs XYZ alignment (step ST8). This makes it possible to detect XY spots normally.

If the first alignment detection unit 71 cannot detect the pupil (NO in step ST6), the inspector performs manual alignment (step ST9) and returns to the XY spot search (step ST3). The pupil cannot be detected when the support portion 1 is not adjusted with respect to the face HB and the front-face cameras 41 and 42 image the portion of the face HB other than the eye E to be inspected. The inspector adjusts the height of the support portion 1 so that the subject's face HB is correctly arranged on the support portion 1, and the inspector further operates the operation knob 5 while observing the monitor 6 to operate the drive unit 50. By driving, the apparatus main body 4 is moved and aligned so that the eye E to be inspected can be observed by the front-face cameras 41 and 42. In this manual alignment, infrared light is emitted from a lighting device arranged in the vicinity of the front-facing cameras 41 and 42.

In the state where the XY spot is detected (YES in step ST4), the first alignment detection unit 71 calculates the center of gravity of the XY spot (step ST10). Then, the drive control unit 73 drives the drive unit 50 by the drive control unit 73 based on the income center of gravity, and performs XYZ alignment of the airflow blowing nozzle 8 with respect to the eye E to be inspected (step ST11, step ST12). ..

In the state where the XYZ alignment is completed (YES in step ST12), the airflow blowing nozzle 8 is still not in the proper position with respect to the eye E to be inspected. Therefore, the drive control unit 73 drives the drive unit 50 to retract the airflow blowing nozzle 8 by 4 mm (step ST13), and stops the irradiation of infrared light (step ST14).

The non-contact tonometer S then performs a second alignment. First, the light source lighting control unit 75 raises the brightness of the visible light source 31 (step ST15). Visible light from the visible light source 31 is scattered inside the cornea of the eye E to be inspected, and this scattered image is acquired by the face camera 41 (step ST16). When the scattered image cannot be acquired, the light source lighting control unit 75 maximizes the brightness of the visible light source 31 and similarly acquires the scattered image.

After acquiring the scattered image (NO in step ST16), the second alignment detection unit 72 acquires the apex position of the cornea, and the drive control unit 73 moves the apparatus main body 4 based on the acquired corneal position to blow airflow. The position of the nozzle 8 is adjusted (step ST17, step ST18). When the position adjustment of the apparatus main body 4 is completed (YES in step ST18), the brightness of the visible light source 31 is lowered (step ST19), and the infrared light source 21 is turned on (step ST20). In this state, the intraocular pressure measurement control unit 74 drives the air injection device 60 to eject air from the airflow blowing nozzle 8 to the eye E to be inspected, detects the reflected light with the flattening sensor 17, and measures the intraocular pressure ( Step ST21).

When the scattered light cannot be detected (NO in step ST16), the second alignment detection unit 72 determines whether the brightness of the visible light source 31 is the maximum by the light source lighting control unit 75 (step ST22), and when it is not the maximum (step ST22). NO) of ST22 increases the brightness of the visible light source 31 and detects the scattered light again (step ST15). On the other hand, when the brightness of the visible light source is maximum (YES in step ST22), the brightness of the visible light source 31 is reduced (step ST23), and the alignment is set again from the first alignment setting.

As described above, the non-contact tonometer S according to the present embodiment aligns the position of the airflow blowing nozzle 8 with respect to the eye to be inspected E in the XY direction and the Z direction based on the Pulkiner image by the first alignment, and further aligns one end. After retracting the apparatus main body 4, the position of the apex of the cornea is detected by the second alignment, and the airflow blowing nozzle 8 is positioned in the Z direction with respect to the apex of the cornea. Therefore, the non-contact tonometer S can directly detect the apex of the cornea of the eye E to be inspected, and it is not necessary to consider the difference in the anterior chamber depth and the corneal curvature of the subject.

<Second Embodiment>
In the above embodiment, the front-face cameras 41 and 42 have the same magnification. In the second embodiment, the shooting magnification of at least one of the two front-face cameras is larger than the shooting magnification of the other shooting device. FIG. 10 is a schematic diagram illustrating a non-contact tonometer according to a second embodiment of the present invention. In this example, the photographing magnification of the frontal camera 92 is larger than the imaging magnification of the frontal camera 91. Therefore, as shown in FIG. 10B, the entire image E to be inspected appears in the image 93 captured by the front camera 91, whereas the image 94 captured by the infrared light of the front camera 92 is covered. The pupil of optometry E appears large. However, if the observation magnification is increased, the range that can be captured by the camera becomes narrower, so the ratio of each side of the effective imaging area of the sensor is the ratio of the imaging magnification so that the observation range is the same as that of a low-magnification camera. The above camera is desirable. Further, it is desirable that the pixel pitch of the sensor is equal to or less than the ratio of the imaging magnification so that the resolution does not decrease.

When a beam of visible light is irradiated in this state, as shown in FIG. 10 (c), the corneal scattering image 98 of the image 97 captured by the front camera 92 is more than the corneal scattering image 96 of the image 95 captured by the front camera 91. Is bigger. In the present embodiment, by performing the second alignment with the high-magnification frontal camera 92, the position of the apex of the cornea can be acquired with higher accuracy. In this case, since the front-facing camera 91 having a low magnification is not used for imaging visible light, it is sufficient to use a transmission filter that transmits only infrared light, so that the number of expensive two-region transmission filters can be increased. It can be reduced to curb price increases.

In the first embodiment, in the second alignment, the position of the apex of the cornea is detected by using one frontal camera to perform Z alignment. In the present invention, the apex of the cornea can be detected by using two frontal cameras 41 and 42. In this case, the corneal apex position can be specified in the XYZ direction, and both XY alignment and Z alignment can be executed in the second alignment.

During the actual measurement, after the first alignment is completed, the eye E to be inspected may move during the second alignment and the XY alignment may shift. Assuming that the XY alignment can be performed only by the first alignment, when the eye E to be inspected moves, the first alignment (XY alignment) must be performed again and then the second alignment (Z alignment) must be performed. In some cases, it is necessary to perform the first alignment and the second alignment alternately. On the other hand, in the second alignment, if the images are taken with the two front-face cameras 41 and 42, the corneal apex position can be specified in the XYZ direction in the second alignment, and both the XY alignment and the Z alignment can be executed. There is no need to perform the first alignment again.

1: Support part 2: Device base 3: Mount 4: Device body 8: Airflow blowing nozzle 10: Intraocular pressure measurement system 11: Air chamber 14: Chamber window glass 13,
15: First dichroic mirror 16: Imaging lens 17: Flattening sensor 18: Pinhole 20: Infrared light irradiation system 21: Infrared light source 22: Aperture 24: Second dichroic mirror 25: Collimeter lens 30: Visible light irradiation System 31: Visible light source 32: Aperture 41: Face camera (photographing device)
42: Face camera (shooting device)
50: Drive unit 60: Air injection device 70: Control unit 71: First alignment detection unit 72: Second alignment detection unit 73: Drive control unit 74: Intraocular pressure measurement control unit 75: Light source lighting control unit

Claims (2)

An apparatus main body having an infrared light irradiation system that irradiates an eye to be inspected with infrared light and an infrared light detection system that detects the infrared light from the eye to be inspected.
A support that supports the position of the subject's face and
A drive unit that relatively moves the device body and the support portion to align the axis of the device body with respect to the eye to be inspected and aligns the device body with the distance to the eye to be inspected.
In an ophthalmic device equipped with
Two imaging devices that substantially photograph the eye to be inspected from different directions and have an imaging magnification of one imaging device larger than that of the other imaging device.
A first alignment detection unit that acquires a Purkinje image of the eye to be inspected from the two images of the eye to be inspected by the infrared light taken by the two imaging devices and detects the position of the eye to be inspected from the Purkinje image. When,
A second alignment detection unit that acquires a scattered image of the cornea of the eye to be inspected by visible light taken by at least one of the two photographing devices and detects the apex of the cornea based on the scattered image.
The drive unit is controlled based on the detection result of the first alignment detection unit to align the main body of the device with respect to the eye to be inspected, and the drive unit is based on the detection result of the second alignment detection unit. A drive control unit that controls the device body to adjust the distance to the eye to be inspected, or to adjust the position and distance.
An ophthalmic device characterized by having. A device main body that irradiates the eye to be inspected with infrared light and detects the infrared light from the eye to be inspected, a support portion that supports the position of the subject's face, and the device main body and the support portion relative to each other. In an ophthalmology device including a moving drive unit, an ophthalmologist who relatively moves the device body and the support unit to align the device body with the eye to be inspected and to align the distance with the eye to be inspected. It ’s a device alignment method.
A step of irradiating the eye to be inspected with infrared rays and photographing the cornea of the eye to be inspected from two different directions at a magnification of one of them being larger than that of the other, substantially simultaneously, to detect a Purkinje image in the eye to be inspected. When,
A step of aligning the main body of the device with the eye to be inspected based on the position of the Purkinje image, and
A step of detecting a scattered image in the cornea by visible light applied to the eye to be inspected, and a step of detecting the scattered image in the cornea.
A step of adjusting the distance of the apparatus main body to the eye to be inspected, or performing alignment and distance adjustment based on the apex of the cornea of the eye to be inspected detected based on the scattered image.
A method of aligning an ophthalmic appliance, which comprises.

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