JP5658018B2 - Ophthalmic examination equipment - Google Patents

Description

  The present invention relates to an ophthalmic examination apparatus for examining a subject's eye.

  A tonometer, which is one of ophthalmic examination apparatuses, examines intraocular pressure. The measured intraocular pressure is used for glaucoma diagnosis and the like.

  The non-contact tonometer measures the intraocular pressure in a non-contact manner by detecting the deformation state of the cornea when a fluid is ejected from the nozzle toward the cornea. The tonometer of Patent Document 1 has an observation system that observes and records the deformed state of the cornea, and records an image of the cornea that is not deformed and / or deformed. However, even such an apparatus has room for improvement in terms of observing the state in the eye.

JP 2006-231052 A

  This invention makes it a technical subject to provide the novel ophthalmic examination apparatus which improves the said point.

  In order to solve the above problems, the present invention is characterized by having the following configuration.

Comprising a detection means for detected over time the first signal associated with the fundus of the pressurized eye with pressurizing means.

  According to the present invention, information related to the fundus of the eye pressurized by the pressurizing means is obtained.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing a specific example of an ophthalmic examination apparatus according to this embodiment. FIG. 2 is a view showing a specific example of an optical system for detecting the deformed state of the cornea, and is a view of the optical system near the nozzle as viewed from above. FIG. 3 is a block diagram showing a specific example of the control system. In FIG. 1, the X direction represents the left-right direction, the Y direction represents the up-down direction, and the Z direction represents the front-rear direction. The following measurement system and optical system are built in a housing (not shown). Further, the housing may be moved three-dimensionally with respect to the subject's eye E by a known alignment moving mechanism. Moreover, a hand-held type (handy type) may be used.

  An outline of the ophthalmic examination apparatus according to the present embodiment will be described. The apparatus includes, for example, a pressure unit 10, a fundus detection system 100, and a cornea detection system 200 (see FIG. 2).

  The pressurizing unit 10 pressurizes the eye E. As the pressure unit 10, for example, a pressure unit such as a transducer that emits ultrasonic waves toward the cornea Ec in addition to the air compression mechanism illustrated in FIG. 1 is used. The direction of pressurization is, for example, an eye axis direction and a direction inclined with respect to the eye axis. The pressurizing unit 10 is preferably configured to apply a pressure to the eye E that deforms the cornea Ec. In addition, the structure which applies weak pressure to the eye E to such an extent that the cornea Ec vibrates slightly may be sufficient.

  The fundus detection system 100 is provided for detecting a first signal related to the fundus of the eye pressurized by the pressure unit 10. For example, the fundus detection system 100 detects the first signal over time. As the fundus detection system 100, an interference optical system 100a that detects an interference state between light reflected from the fundus and other light is preferably used as shown in FIG.

  The interference optical system (optical interferometer) 100 a includes a light source 102, a light splitter (for example, the illustrated coupler 104), and a detector 120. The interference optical system 100a divides the light emitted from the light source 102 by the light splitter, and irradiates the eye E with at least one of the divided lights. Then, the detector 120 detects an interference state between the light reflected from the fundus and other light. The state of the fundus oculi Ef is detected based on the output signal from the detector 120.

  For example, the position of the fundus in the depth direction is detected. Thereby, when force is applied to the cornea, the position of the fundus is detected. In addition, the state of the fundus is detected with high accuracy. Note that the Doppler interferometer may detect a speed related to a change in the position of the fundus (for example, a response speed of deformation of the fundus).

  The interference optical system 100a detects, for example, an interference state between light reflected by the eye and reference light formed in the apparatus. The interference optical system 100a may be configured to detect an interference state between two lights (for example, corneal reflection and fundus reflection) reflected by the eye.

  The interference optical system 100a may be an interferometer that detects an interference signal related to one point on the fundus oculi Ef, or may be an interferometer that detects a plurality of interference signals related to the transverse direction of the fundus oculi. In addition to detecting the fundus, the interference optical system 100a may detect the state of the cornea. Further, the interference optical system 100a may be an interference optical system that measures the axial length of the eye E.

  Note that the fundus detection system 100 is not limited to a photodetector, and uses a configuration that obtains information on the fundus oculi Ef by transmitting and receiving detection waves such as X-rays and magnetism. Since force acts in the depth direction of the eye when the cornea is pressurized, the fundus detection system 100 should be a device that can detect changes in the fundus (eg, position change, speed of change) in the depth direction. Is preferred.

  The cornea detection system 200 is provided to detect a second signal related to the cornea Ec of the eye E pressurized by the pressure unit 10. As the cornea detection system 200, for example, a light detector such as an imaging unit (for example, Scheimpflug camera, OCT, slit lamp) that captures a cross-sectional image of the cornea is used in addition to the optical system illustrated in FIG. Based on the detection signal from the photodetector, the state of the pressurized cornea Ec is detected. The cornea detection system 200 is not limited to a photodetector, and a configuration is used in which information on the cornea Ec is obtained by transmitting and receiving a radiator such as X-rays or magnetic energy.

  Note that the detection of the first signal and the detection of the second signal may be performed by the same detection system. For example, the interference optical system 100a may combine detection of the first signal and detection of the second signal. The interference optical system 100a detects the interference state between the light reflected from the cornea and other light with a detector.

  The control unit 80 (see FIG. 3) controls the pressurizing unit 10, the fundus detection system 100, and the cornea detection system 200. Using the first signal detected by the fundus detection system 100, the control unit 80 measures at least one of intraocular pressure, whole eye hardness, fundus hardness, and axial length. The control unit 80 may measure at least one of the intraocular pressure and the hardness of the entire eye using the first signal detected by the fundus detection system 100 and the second signal detected by the cornea detection system 200. good. The controller 80 inspects the eye characteristics using the response result of the pressurized eye. This apparatus is used as at least one of a tonometer, an eye hardness meter, a fundus hardness meter, and an axial length measuring device, for example.

  For example, the fundus detection system 100 can observe the state of the fundus oculi Ef while the cornea is being pressurized. Further, the fundus detection system 100 can observe the state of the fundus before the cornea is pressurized or after the cornea is pressurized. The fundus detection system 100 is used for evaluation of the fundus associated with pressurization on the cornea.

  A wave generated when the cornea is pressurized propagates through an intraocular medium such as the anterior chamber, the crystalline lens, and the vitreous body, and then reaches the fundus. Therefore, the fundus detection system 100 can observe the state of the fundus that has received such a wave.

  According to this, the relationship between the state of the fundus that has received waves generated when the cornea is pressurized and the intraocular pressure is evaluated. In addition, it is possible to evaluate in consideration of the hardness of the intraocular substance caused by the intraocular pressure. For example, when the intraocular pressure is high, the intraocular substance is hardened by the compression, and the wave is easily transmitted to the fundus. For this reason, the amount of deformation of the fundus is large. On the other hand, when the intraocular pressure is low, the intraocular substance is soft and the waves are not easily transmitted to the fundus. For this reason, the amount of deformation of the fundus is reduced. Here, the change in the fundus when pressure is applied to the cornea is influenced by the intraocular pressure. Therefore, by observing the state of the fundus, it is possible to measure the intraocular pressure in consideration of the pressure of the entire eye.

  Further, by observing the state of the fundus of the pressurized eye, it is possible to evaluate the fundus hardness (for example, the hardness of the fundus side sclera). For example, when the fundus side sclera is hard, the deformation amount of the fundus is small. On the other hand, when the fundus side sclera is soft, the deformation amount of the fundus is large. It is possible to comprehensively evaluate the intraocular pressure and the fundus hardness.

  The evaluation regarding the intraocular pressure and fundus hardness as described above may be used for diagnosis of cases such as intense myopia and glaucoma. For example, if the fundus is soft, the length of the long eye axis is likely to increase, and glaucoma is likely to occur.

  Further, the fundus detection system 100 can observe the position of the eyeball of the eye E to which force is applied. The fundus detection system 100 is used to evaluate the movement of the eyeball associated with pressurization on the cornea. For example, when a force is applied to the cornea Ec, the movement of the eyeball in the depth direction may affect the detection of the state of the cornea Ec as described above. Further, even if the cornea is not vibrating, the vibration of the eyeball may be mistaken for the vibration of the cornea. Therefore, the fundus detection system 100 is used to overcome these problems.

  Hereinafter, an example of an embodiment in which an air compression mechanism is applied as the pressurizing unit 10, an oblique incidence detection optical system and the interference optical system 100a as the cornea detection system 200, and an interference optical system 100a as the fundus detection system will be described. To do.

  <Non-contact corneal pressurization unit> 1 is a cylinder part for air compression, 2 is a piston, and these are used as an air compression mechanism which compresses the air ejected to the eye to be examined. Reference numeral 3 denotes a rotary solenoid. When a drive current is applied to the rotary solenoid 3 (hereinafter referred to as the solenoid 3), the piston 2 is compressed in the compression direction (arrow A direction) via the arm 4 and the connecting rod (piston rod) 5. ). The air compressed in the air compression chamber 34 in the cylinder portion 1 by the movement of the piston 2 is passed through a tube (which may be a pipe) 70 connected to the tip of the cylinder 1 and an airtight chamber 71 for storing the compressed air. , And ejected from the nozzle 6 toward the cornea of the eye E of the subject. The cylinder portion 1 is disposed in parallel to the horizontal plane (XZ plane), and the piston 2 is moved horizontally in the cylinder portion 1 by driving the solenoid 3 to compress the air.

  For example, the cylinder part 1 is arranged with its longitudinal direction parallel to the horizontal direction, and the inner surface of the cylinder part 1 guides the piston 2. For this reason, the moving direction (compression direction) of the piston 2 is the horizontal direction. Each of the above-described constituent members is disposed on a stage provided in the casing of the apparatus main body (not shown).

  Further, the solenoid 3 is provided with a coil spring (not shown), and when the applied current is cut or reduced, the piston 2 moved in the compression direction is moved in the return direction (arrow A) by the biasing force in the return direction of the coil spring. In the opposite direction) to return to the initial position. Further, in the present embodiment, since the air compression mechanism is disposed above the axis of the nozzle 6 (a configuration in which the axis of the nozzle 6 is removed), tears and the like may be sucked into the cylinder unit 1. There are few.

  A transparent glass plate 8 holds the nozzle 6 and transmits observation light and alignment light. The glass plate 8 is used as a part of a wall constituting the hermetic chamber 71. Reference numeral 9 denotes a transparent glass plate provided on the back surface of the nozzle 6, which constitutes the rear wall of the hermetic chamber 71 and transmits observation light and alignment light. Behind the glass plate 9, the observation / alignment optical system 11 is arranged so that the observation optical axis and the alignment optical axis and the axis of the nozzle 6 are coaxial. Description is omitted.

  12 is a pressure sensor for detecting the pressure in the airtight chamber 71, and 13 is an air vent hole. The resistance until the initial speed is applied to the piston 2 is reduced by the air vent hole 13, and a rising pressure change proportional to time can be obtained.

  <Cornea Detection System> 14 is an infrared LED for detecting corneal deformation (see FIG. 2), and the light emitted from the LED 14 is collimated by the collimator lens 15 and projected onto the cornea of the eye to be examined. The light reflected by the cornea passes through the light receiving lens 16 and the pinhole plate 17 and is received by the photodetector 18 which is a light receiving element. The corneal deformation detection optical system is arranged so that the amount of light received by the photodetector 18 is maximized when the eye to be examined is in a predetermined deformed state (for example, an applanation state). In other words, the cornea detection system detects a deformed state of the cornea by projecting an index to the cornea and receiving the reflected light.

  <Interference Optical System> Returning to FIG. The interference optical system 100a irradiates the fundus with measurement light. The interference optical system 100a detects the interference state between the measurement light reflected by the fundus and the reference light by the light receiving element (detector 120). The interference optical system 100 a splits the light beam emitted from the light source 102 into measurement light and reference light by a coupler (beam splitter) 104. The interference optical system 100a guides the measurement light to the fundus oculi Ef by the measurement optical system (for example, the dichroic mirror 30), and guides the reference light to the reference optical system 110a. Thereafter, the detector (light receiving element) 120 receives light (interference light) obtained by combining the measurement light reflected by the fundus oculi Ef and the reference light.

  The interference optical system 100a irradiates the cornea with measurement light. In the interference optical system 100a, the detector 120 detects an interference state between the measurement light reflected by the cornea and the reference light. The interference optical system 100a guides the measurement light to the cornea Ec by the measurement optical system (for example, the dichroic mirror 30), and guides the reference light to the reference optical system 110b. Thereafter, the detector 120 receives light (interference light) obtained by combining the measurement light beam reflected by the cornea Ec and the reference light.

  In the case of the Fourier domain type, the spectral intensity of light is detected by the detector 120, and a depth profile (A scan signal) is obtained by Fourier-transforming data relating to the spectral intensity. Examples of the interference optical system 100a include Spectral-domain (SD system) and Swept-source (SS system). Moreover, Time-domain (TD system) may be used. In this case, a technique of optical coherence tomography can be used.

  In the case of the SD system, a low-coherent light source (broadband light source) is used as the light source 102, and the detector 120 is provided with a spectroscopic optical system (spectrum meter) that separates light having a certain wavelength width into each wavelength (frequency) component. It is done. The spectrum meter includes, for example, a diffraction grating and a line sensor.

  In the case of the SS system, a wavelength scanning light source (wavelength variable light source) that changes the emission wavelength at a high speed with time is used as the light source 102, and a single light receiving element is provided as the detector 120, for example. The light source 102 includes, for example, a light source, a fiber ring resonator, and a wavelength selection filter. Examples of the wavelength selection filter include a combination of a diffraction grating and a polygon mirror, and a filter using a Fabry-Perot etalon.

  The reference optical system 110 includes a first reference optical system 110a and a second reference optical system 110b. The first reference optical system 110a generates first reference light that is combined with light acquired by reflection of measurement light on the fundus oculi Ef. The second reference optical system 110b generates second reference light that is combined with light acquired by reflection of measurement light from the cornea. The beam splitter 111 as a light splitting unit splits the reference light sent from the coupler 104 and generates first reference light and second reference light.

  The reference optical system 110 may be a Michelson type or a Mach-Zehnder type. The reference optical system 110 is configured by, for example, a reflection optical system (for example, a reference mirror) illustrated in FIG. Then, the reference optical system 110 returns the light transmitted from the coupler 104 to the coupler 104 again by reflecting the light from the reflection optical system, and guides it to the detector 120. As another example, the reference optical system 110 is constituted by a transmission optical system (for example, an optical fiber), and guides the light from the coupler 104 to the detector 120 by transmitting the light without returning.

  The reference optical system 110a has a configuration for changing the optical path length difference between the measurement light and the first reference light by moving an optical member arranged in the reference optical path. For example, the first reference mirror 112 is moved in the optical axis direction by driving the drive mechanism 55. The configuration for changing the optical path length difference may be arranged in the measurement optical path of the measurement optical system 106.

  When detecting the state of the fundus, the optical path difference is adjusted so that the optical path length of the light applied to the fundus and the optical path length of the first reference light substantially coincide. Then, the spectrum data detected by the detector 120 is input to the control unit 80 (see FIG. 3), and the frequency of the spectrum data is analyzed using Fourier transform. Thereby, information in the depth direction of the eye E is acquired (see peaks AR and PR in FIG. 4).

  The second reference optical system 110b fixes the optical path length so that the cornea Ec is included in the interference signal detectable range (a range in which the depth profile can be acquired) when the alignment is completed. In the case of a Fourier domain interferometer, an interference signal is obtained within a range from a position where the optical path lengths of the measurement light and the second reference light match to a predetermined distance.

  Therefore, when the alignment in the Z direction is properly adjusted, interference between the measurement light reflected by the cornea and the second reference light occurs, and an interference signal due to the interference light is detected as an A scan signal ( (See peaks AC and PC in FIG. 4).

  <Control System> The control system will be described with reference to FIG. The control unit 80 performs control of the entire apparatus, measurement of intraocular pressure, and the like. The control unit 80 is connected to the detection circuit 21, the processing circuit 22, the drive circuit 23, the infrared light source 14, the photodetector 18, the light source 102, the detector 120, and the memory 81.

  The detection circuit 21 processes the detection signal output from the pressure sensor 12. The processing circuit 22 processes the light reception signal output from the photodetector 18. The drive circuit 23 drives the solenoid 3.

  The operation of the apparatus having the above configuration will be described. When a trigger signal for starting measurement is input, the control unit 80 applies a current to the solenoid 3 via the drive circuit 23. When the solenoid 3 is operated and the driving force is transmitted to the piston 2 via the arm 4 and the rod 5, the piston 2 is moved. The air compressed in the cylinder portion 1 compresses the air in the airtight chamber 71 through the tube 70. Then, compressed air is blown against the cornea Ec through the nozzle 6. As a result, the cornea Ec is gradually deformed.

  The light projected from the LED 14 is applied to the cornea, and the light reflected by the cornea enters the photodetector 18. And the state of the cornea is detected using the detection signal output from the photodetector 18. The processing circuit 22 processes the signal from the photodetector 18 and detects that the cornea Ec has reached the applanation state by detecting that the amount of received light shows a predetermined peak.

  The control unit 80 processes the detection signal output from the pressure sensor 12 using the detection circuit 21 and monitors the pressure value. Then, the control unit 80 obtains a pressure value when the applanation state is detected, and calculates an intraocular pressure value based on the pressure value.

<Ocular fundus observation>
The control unit 80 controls the interference optical system 100a and detects the state of the fundus when the cornea is deformed by the air compression mechanism. Furthermore, the control unit 80 may detect the state of the fundus before and after deformation of the cornea.

  The controller 80 emits light from the light source 102. Light (measurement light) from the light source 102 is emitted toward the fundus and cornea of the eye E, and the reflected light is guided to the detector 120. Further, the reference light is guided to the detector 102 through the optical paths of the first reference optical system 110a and the second reference optical system 110b.

  When the alignment is completed, an interference signal between the cornea reflected light and the second reference light is detected as an A scan signal (see FIG. 4). The interference signal AC corresponds to the front surface of the cornea, and the interference signal PC corresponds to the rear surface of the cornea.

  The position where the interference signal between the fundus reflection light and the first reference light is detected varies depending on the axial length of the eye E. The control unit 80 controls the driving of the driving mechanism 55 and moves the first reference mirror 112 continuously or stepwise. And the control part 80 acquires spectrum data one by one by the detector 120, and obtains the A scan signal in each position. The control unit 80 controls driving of the driving mechanism 55 so that an interference signal related to the fundus reflection light and the first reference light is detected as an A scan signal.

  Then, when the optical path difference between the measurement light and the first reference light is reduced and the fundus oculi Ef is included in the detection range, an interference signal corresponding to the fundus is detected (see FIG. 4B). AR is an interference signal corresponding to the retina surface, and PR is an interference signal corresponding to the rear surface of the retina.

  The control unit 80 specifies the A scan signal from which the interference signal corresponding to the fundus is acquired from each A scan signal. In this case, the control unit 80 determines the presence or absence of an interference signal including fundus reflection using the luminance value of the interference signal. Then, the control unit 80 controls the drive mechanism 55 and arranges the first reference mirror 112 at a position where the A scan signal including the fundus oculi signal is acquired.

<Observation of fundus condition regarding corneal deformation>
When a signal corresponding to the fundus is acquired, the control unit 80 stores the A scan signal in the memory 81 as needed. The control unit 80 analyzes each A scan signal stored in the memory 81 and obtains a change in the fundus over time related to corneal deformation. The A-scan signal is recorded continuously or stepwise and is used to evaluate the fundus associated with corneal deformation.

  For example, the control unit 80 detects a change in the fundus in the depth direction based on the A scan signal. When the positions of the fundus before and after deformation are compared during corneal deformation, the degree of deformation of the fundus affected by the compressed air (for example, the amount of deformation (displacement), the deformation speed, etc.) is determined. The position of the fundus is obtained from an interference signal (for example, interference signal AR, interference signal PR) corresponding to the fundus. Note that the control unit 80 may obtain a temporal change regarding the position of the fundus. The controller 80 may apply the Doppler OCT analysis to quantify the velocity related to the position change of the fundus.

  The control unit 80 measures intraocular pressure using the degree of deformation of the fundus. For example, the control unit 80 measures the intraocular pressure using the relationship between the degree of deformation of the fundus and the intraocular pressure. In addition, the degree of deformation of the fundus may be used as one of the parameters for changing the intraocular pressure value calculated by a known measurement method (see FIG. 2). Note that the control unit 80 may use the detection result of the pressure sensor 12 when the amount of deformation of the fundus reaches a certain amount for the calculation of the intraocular pressure value.

<Observation of corneal state related to corneal deformation>
The controller 80 detects a change in the cornea in the depth direction based on the A scan signal. When the position of the cornea is compared during the corneal deformation, before the deformation, and after the deformation, the degree of deformation of the cornea affected by the compressed air (for example, the deformation amount (displacement amount), the deformation speed, etc.) is obtained. The position of the cornea is obtained from an interference signal (for example, interference signal AC, interference signal PC) corresponding to the cornea. Note that the control unit 80 may obtain a temporal change regarding the position of the cornea. The controller 80 may apply the Doppler OCT analysis to quantify the velocity related to the change in the position of the cornea.

  The control unit 80 measures the intraocular pressure based on the deformed state of the cornea. For example, the control unit 80 measures the intraocular pressure using the relationship between the degree of deformation of the cornea and the intraocular pressure. In addition, the degree of deformation of the cornea may be used as one of the parameters for changing the intraocular pressure value calculated by a known measurement method (see FIG. 2). Note that the configuration of the cornea may be detected using the interference optical system 100a without providing the configuration as shown in FIG.

  According to the above configuration, since the state of the cornea and the fundus is observed by the interference signal, both the fundus and the cornea are deformed. Therefore, the evaluation of the fundus related to the corneal deformation and the evaluation of the cornea itself are appropriately associated.

  Note that the control unit 80 can acquire the position of the eyeball when radiant energy is applied to the cornea by detecting the positions of both the cornea and the fundus. The movement information of the eyeball related to the corneal deformation is used for evaluation of intraocular pressure measurement.

  In the above embodiment, the control unit 80 may acquire a change in the axial length related to corneal deformation. For example, the control unit 80 can acquire the position information of the first reference mirror 112 when the A scan signal including the interference signals corresponding to the cornea and the fundus can be acquired, and the positions of the interference signal AC and the interference signal PR in the A scan signal. The axial length is calculated based on the information (for the measuring method of the axial length, see, for example, JP 2007-313208 A). Since changes in the axial length over time are information resulting from changes in both the cornea and the fundus, it is considered useful for evaluating the eyeball related to corneal deformation.

  In the above-described embodiment, the control unit 80 may acquire information of each layer of the fundus by signal processing on the A scan signal and detect a change in the layer. For example, a change in layer thickness associated with corneal deformation is used for measuring intraocular pressure.

  In the interference optical system 100a, the optical scanner may be provided in the measurement optical path. For example, the control unit 80 drives the optical scanner to scan the measurement light on the fundus in the transverse direction. The control unit 80 obtains a fundus tomographic image related to corneal deformation based on the A scan signal acquired at each scanning position. The obtained tomographic image is analyzed by image processing and used for measurement. For example, a change in fundus shape at the time of corneal deformation is used for measurement. Further, the detection result of the pressure sensor 12 when a part of the surface of the fundus has a certain shape (for example, a concave shape) may be used for the measurement.

  The interference optical system shown in FIG. 1 is configured to obtain an interference signal by causing interference between the reference light generated in the apparatus and the measurement light acquired by reflection at each part of the eye to be examined. However, the present invention is not limited to this. For example, the interference optical system has a configuration in which light acquired by reflection on the cornea and light acquired by reflection on the fundus are caused to interfere, and a light receiving element receives the interfered light to obtain an interference signal ( A so-called dual beam type) may be used.

It is the schematic which shows the specific example of the ophthalmic examination apparatus which concerns on this embodiment. It is a figure which shows the specific example of the optical system which detects the deformation | transformation state of a cornea, Comprising: It is the figure which looked at the optical system near a nozzle from the upper direction. It is a block diagram which shows the specific example of a control system. It is an example which shows distribution of the interference signal regarding a depth direction.

DESCRIPTION OF SYMBOLS 10 Pressurization unit 100 Fundus detection system 102 Light source 104 Optical splitter (coupler)
120 detector 200 cornea detection system 100a interference optical system

Claims (2)

Ophthalmologic examination apparatus comprising a detecting means for detected over time the first signal associated with the fundus of the pressurized eye with pressurizing means. The ophthalmic examination apparatus according to claim 1, wherein the detection unit detects the first signal by Doppler OCT .

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