JP7528640B2 - Opthalmography device and control program for optometric device - Google Patents

Description

The present disclosure relates to an optometry device that tests the visual function of a subject's eye and a control program for the optometry device.

Various types of optometry devices for testing the visual function of the subject's eye have been known. For example, there are optometry devices that test the ocular refractive power (spherical power, cylindrical power, cylindrical axis angle, etc.) of the subject's eye, as well as the visual function of the subject's eye with respect to strabismus (see Patent Documents 1 and 2).

JP 2005-192757 A JP 2018-171139 A

However, with conventional technology, the eye refractive power of subjects with heterophoria was only tested with a prism amount applied. Some subjects with heterophoria are able to fuse distant or near targets with the convergence force of their own eyes even without a prism prescription. However, converging the eyes involves physiological accommodation, which places a strain on the refractive state of the eyes. For this reason, conventional eye examination devices were not able to present information that would allow for appropriate prescription of corrective lenses for the subject.

The technical objective of this disclosure is to provide an optometry device and a control program for the optometry device that can provide optometry information for more appropriately prescribing corrective lenses for subjects with strabismus.

In order to solve the above problems, the present disclosure is characterized by having the following configuration:

(1) An eye examination device according to the present disclosure is an eye examination device for testing the visual function of a subject's eye, comprising: an eye target presenting means having a pair of eye target presenting means for a right eye and an eye target presenting means for a left eye for presenting an eye target to the left and right subjects'eyes; an eye refraction measuring means for objectively measuring the eye refraction of the subject's eye; a prism amount changing means for changing the prism amount imparted to at least one of the left and right subjects' eyes ; and an output control means, wherein the output control means presents an eye target to the subject's eye by the eye target presenting means, changes the prism amount imparted to the subject's eye to at least two different states by the prism amount changing means, obtains the eye refraction of the subject's eye in each state where the prism amount is changed by the eye refraction measuring means , and outputs the obtained eye refraction in correspondence with each prism amount imparted to the subject's eye.
(2) The control program for an eye examination apparatus according to the present disclosure is a control program for an eye examination apparatus used in an eye examination apparatus including an eye target presenting means having a pair of eye target presenting means for the right eye and an eye target presenting means for the left eye for presenting an eye target to the left and right eyes to be examined, an eye refraction measuring means for objectively measuring the eye refraction of the eye to be examined, and a prism amount changing means for changing the prism amount applied to at least one of the left and right eyes to be examined, and is characterized in that the control unit of the eye examination apparatus executes the following steps: an eye target presenting step of presenting an eye target to the eye to be examined by the eye target presenting means; an eye refraction acquisition step of changing the prism amount applied to the eye to be examined to at least two different states by the prism amount changing means and acquiring the eye refraction of the eye to be examined in each state where the prism amount is changed by the eye refraction measuring means; and an output step of outputting the acquired eye refraction in correspondence with each prism amount imparted to the eye to be examined.

The present disclosure can provide optometric information to more appropriately prescribe corrective lenses for subjects with strabismus.

FIG. 1 is a diagram showing a schematic external configuration of an optometry apparatus. FIG. 2 is a diagram showing an optical system arranged in a measurement unit. 1 is a schematic configuration diagram of the inside of an optometry apparatus as viewed from the front. 2 is a schematic configuration diagram of the inside of the optometry apparatus as viewed from the side. FIG. 2 is a schematic configuration diagram of the inside of the optometry apparatus as viewed from above. FIG. FIG. 2 is a diagram showing a control system of the optometric apparatus. 4 is an example of an anterior ocular segment image of a subject's eye acquired by an imaging element. 1 is a schematic example showing the results of eye refractive power measurement over time for a test eye to which a prism amount has been applied. 13 is an example of the measurement results and characteristic information of eye refractive power outputted in correspondence with the amount of prism applied to the left eye. 13 is a schematic example showing the measurement results of minute displacement of eye position. 13 is an example of characteristic information as a measurement result of a minute displacement of eye position (eyeball) that is output in correspondence with the amount of prism applied to the left eye. Regarding the characteristic information of the eye position displacement, this is an example in which the eye position displacement with respect to the amount of prism applied to the eye is frequency analyzed, and the result is graphed and output. 13 is an example of an output of the measurement result of eye refractive power when the prism amount is continuously changed.

[overview]
Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. Figures 1 to 6 are diagrams illustrating the configuration of an optometry apparatus according to an embodiment.

For example, an eye examination apparatus for testing the visual function of a subject's eye includes an eye tester presenting means (e.g., an eye tester presenting optical system 30) for presenting eye tests to the left and right subject's eyes, the eye tester having a pair of eye tester presenting means for the right eye and an eye tester presenting means for the left eye. For example, the eye examination apparatus includes an eye refractive power measuring means (e.g., an objective measuring optical system 10) for objectively measuring the eye refractive power of the subject's eye. For example, the eye examination apparatus includes a prism amount changing means (e.g., a deflection mirror 81, a driving mechanism 82, a control unit 70) for changing the amount of prism applied to at least one of the left and right subject's eyes. For example, the eye examination apparatus includes an output control means (e.g., a control unit 70, a monitor 6a). For example, the output control means controls the target presenting means, the prism amount changing means, and the eye refractive power measuring means, presents a target to the test eye using the target presenting means, acquires the eye refractive power of the test eye in at least two states in which the prism amount applied to the test eye is changed by the prism amount changing means using the eye refractive power measuring means, and outputs the acquired eye refractive power in correspondence with the prism amount applied to the test eye. For example, the output control means controls the target presenting means, the prism amount changing means, and the prism amount changing means.

For example, the prism amount changing means may be configured to include a light deflection member (e.g., a deflection mirror 81) disposed between the optical system of the eye refraction measurement means and the subject's eye, and the light deflection member may be driven. This changes the direction of the target light beam (e.g., the light beam from the target presentation means) toward the subject's eye and the measurement light beam from the eye refraction measurement means, making it possible to impart any prism amount to the subject's eye. For example, the prism amount changing means may be configured to actually place a prism in front of the subject's eye. Also, for example, the prism amount changing means may be configured to shift the position at which the target is presented by the target presentation means in the left-right or up-down direction.

For example, the eye examination device includes an eye characteristic acquisition means (e.g., a control unit 70) that acquires characteristic information of the subject's eye in each state of change in the amount of prism imparted to the eye when the eye refractive power is measured by the eye refractive power measurement means. For example, the output control means outputs the characteristic information acquired by the eye characteristic acquisition means in correspondence with the amount of prism imparted to the subject's eye.

For example, the eye examination device may include an eye refractive power change acquisition means (e.g., an objective measuring optical system 10, a control unit 70) that acquires the change over time in the eye refractive power of the test eye by an eye refractive power measurement means. For example, the eye characteristic acquisition means is a means for acquiring characteristic information of the change over time in the eye refractive power based on the change over time in the eye refractive power acquired by the eye refractive power change acquisition means, and the output control means outputs the characteristic information of the change over time in the eye refractive power acquired by the eye characteristic acquisition means in correspondence with the prism amount applied to the test eye. For example, the characteristic information of the change over time in the eye refractive power includes at least one of the period, amplitude, variance, and frequency of occurrence of high frequency components (HFC) of the change over time in the eye refractive power.

For example, the eye examination apparatus includes an anterior eye imaging means (e.g., an observation optical system 50, an image sensor 52) that images the anterior eye of the subject's eye. For example, the eye characteristic acquisition means includes a micro-displacement acquisition means (e.g., a control unit 70) that acquires information on minute displacements over time of the eye movement of the subject's eye based on the anterior eye image of the subject's eye captured by the anterior eye imaging means. For example, the micro-displacement of eye movement is a displacement of the eye position. For example, the micro-displacement acquisition means acquires information on minute displacements of the eye movement during eye examination by detecting a change over time in the position of the pupil (e.g., the position of the pupil center) of the anterior eye image of the subject's eye and the position of the corneal apex of the subject's eye based on at least one of the position of the pupil (e.g., the position of the pupil center) of the anterior eye image of the subject's eye and the position of the corneal apex of the subject's eye. For example, the position of the pupil is detected by capturing an anterior eye image by the anterior eye imaging means and analyzing the captured anterior eye image. For example, the position of the corneal apex of the test eye is detected by capturing an anterior segment image, including a Purkinje image formed by a target projected onto the cornea, using an anterior segment imaging means, and analyzing and processing the captured anterior segment image to identify the Purkinje image.

For example, the output control means outputs information on the micro-displacement acquired by the micro-displacement acquisition means in correspondence with the prism amount applied to the subject's eye. For example, the information on the micro-displacement includes at least one of the period, amplitude, variance, and frequency of occurrence of high-frequency components of the micro-displacement of eye movement.

For example, when the output control means outputs the characteristic information acquired by the eye characteristic acquisition means (e.g., at least one of the eye refractive power change acquisition means and the micro-displacement acquisition means) in correspondence with the prism amount applied to the subject's eye, the output control means judges the level of the characteristic information (the level of the characteristic information) in each state in which the application of the prism amount is changed based on the characteristic information, and outputs the judgment result together. For example, the judgment result is output so as to be displayed on a display means (e.g., monitor 6a). For example, the judgment result is accompanied by identification information (e.g., mark 211, mark 212) indicating the level of the characteristic information. For example, the identification information is attached to the minimum value of the level of the characteristic information. For example, the identification information is attached to the maximum value of the level of the characteristic information. For example, the identification information may be color-coded information that divides the level of the characteristic information into at least two levels. For example, the identification information may be information that divides the characteristic information into at least two levels of high and low, and classifies the divided levels by level (e.g., level 1, level 2, etc.).

For example, the eye examination apparatus includes an eye position acquisition means (e.g., a control unit 70) that acquires the eye position of the subject eye. For example, the eye position acquisition means acquires the eye position of the subject eye in a state where the subject eye is in a fusion-free eye position (the eye position when fusion is removed while the subject eye is fixated with both eyes). For example, the eye examination apparatus includes a prism amount determination means (e.g., a control unit 70) that determines the prism amount for at least two states when the eye refractive power of the subject eye is measured by the eye refractive power measurement means based on the eye position acquired by the eye position acquisition means. For example, the eye position acquisition means includes an anterior eye imaging means that images the anterior eye of the subject eye, presents an eye target to one eye by an optotype presenting means, switches between a presenting state and a non-presenting state of the optotype to the other eye, and acquires the eye position of the subject eye based on at least one of the position of the pupil (e.g., the position of the pupil center) of the anterior eye image of the subject eye captured by the anterior eye imaging means and the position of the corneal apex of the subject eye. The eye position acquisition means may acquire the eye position of the subject eye by inputting a separately measured eye position through an input means (e.g., switch unit 6b).

For example, the eye examination device may be provided with a prism amount setting means (e.g., controller 6) that allows the examiner or subject to arbitrarily set the prism amount for at least two states when the eye refractive power of the subject's eye is measured by the eye refractive power measurement means.

For example, the output control means controls the prism amount changing means to continuously change the amount of prism applied to the subject's eye while continuously executing measurements by the ocular refractive power measuring means, and continuously obtains the ocular refractive power corresponding to the amount of prism applied to the subject's eye. In this case, detailed measurement results of the ocular refractive power corresponding to the amount of prism applied to the subject's eye can be obtained in a short measurement time. This makes it possible to provide more detailed eye examination information for appropriately prescribing corrective lenses for subjects with heterophoria.

For example, one of the at least two states in which the prism amount applied to the test eye is changed includes a prism amount of zero. The state in which a prism amount of zero is applied is a state in which no prism amount is applied to the test eye. For example, the output control means determines a prism amount corresponding to an ocular refractive power that has changed by a predetermined power step or more (for example, 0.25 diopters or more) from the ocular refractive power in the state of zero prism amount based on the ocular refractive power obtained in each prism state, and outputs the determined prism amount. For example, the output control means determines a correspondence relationship between the prism amount applied to the test eye and the ocular refractive power based on the ocular refractive power obtained in each prism state, and determines a prism amount corresponding to an ocular refractive power that has changed by a predetermined power step or more from the ocular refractive power in the state of zero prism amount based on this correspondence relationship. For example, the correspondence relationship between the prism amount and the ocular refractive power is determined as a function formula, or a table or graph of the correspondence relationship. This makes it possible to provide information on a prism prescription that is advantageous as a change in ocular refractive power. Conversely, when the prism amount is such that the change in ocular refractive power is less than the specified power step, there is little significant difference in ocular refractive power, and so information can be provided that the prism prescription is not effective.

For example, the eye examination device may include an interpolation means (control unit 70) that interpolates the relationship between the prism amount and the ocular refractive power for which the ocular refractive power has not been measured by the ocular refractive power measurement means from the results of ocular refractive power measurements that have already been performed. In this case, the output control means determines and outputs the prism amount corresponding to the ocular refractive power that has changed by more than a predetermined power step based on the interpolation results by the interpolation means. This makes it possible to provide information that is useful for prism prescriptions, for example, when obtaining characteristic information on changes in ocular refractive power over time, without having to frequently change the prism amount applied to the test eye.

For example, the eye examination device may be provided with a selection means (e.g., control unit 70, controller 6) for selecting whether to perform measurement using the eye refractive power measurement means when the subject's eye is in a binocular vision state or to perform measurement using the eye refractive power measurement means when the subject's eye is in a monocular vision state.

Note that this disclosure is not limited to the device described in this embodiment. For example, a control program (software) that performs the functions of the above embodiment may be supplied to a system or device via a network or various storage media. Then, a control unit (e.g., a CPU) of the system or device may read and execute the program.

For example, a control program for an eye examination device used in an eye examination device equipped with an eye target presenting means having a pair of eye target presenting means for the right eye and an eye target presenting means for the left eye for presenting an eye target to the left and right eyes to be examined, an eye refractive power measuring means for objectively measuring the eye refractive power of the eye to be examined, and a prism amount changing means for changing the amount of prism applied to at least one of the left and right eyes to be examined causes a control unit of the eye examination device to execute an eye target presenting step of presenting an eye target to the eye to be examined by the eye target presenting means, an eye refractive power acquisition step of acquiring the eye refractive power of the eye to be examined measured by the eye refractive power measuring means in at least two states in which the amount of prism applied to the eye to be examined is changed by the prism amount changing means, and an output step of outputting the acquired eye refractive power in correspondence with the amount of prism applied to the eye to be examined.

[Example]
An example of the optometry apparatus according to the present embodiment will be described. Fig. 1 is a diagram showing a schematic configuration of the exterior of the optometry apparatus 1. In this example, the optometry apparatus 1 will be described as an example of an apparatus equipped with an objective measurement unit that objectively measures the optical characteristics (e.g., ocular refractive power) of the subject's eye and a subjective measurement unit that subjectively measures the optical characteristics (e.g., ocular refractive power) of the subject's eye E. In Fig. 1, the left-right direction (horizontal direction) as viewed from the subject's side will be described as the X direction, the up-down direction (vertical direction) as the Y direction, and the front-rear direction as the Z direction.

For example, the eye examination device 1 includes a housing 2, a presentation window 3, a forehead rest 4, a chin rest 5, a controller 6, a measurement unit 7, an imaging unit 90, an anterior eye illumination unit 95, etc.

The presentation window 3 is used to present the visual target to the subject's eye E. The forehead rest 4, against which the subject's forehead rests, is used to maintain a constant distance between the subject's eye E and the eye examination device 1. The chin rest 5, on which the subject's chin rests, is used to maintain a constant distance between the subject's eye E and the eye examination device 1. Note that the chin rest 5 is not necessarily provided.

The controller 6 includes a monitor 6a, a switch section 6b, etc. The monitor 6a displays various information (e.g., the measurement results of the subject's eye E, etc.). The monitor 6a is a touch panel, and also functions as the switch section 6b. The switch section 6b is used to perform various settings (e.g., input of a start signal, etc.). A signal corresponding to an operation instruction from the controller 6 is output to the control section 70, which will be described later, by at least one of wired communication via a cable or the like and wireless communication via infrared or the like.

The imaging unit 90 includes an imaging optical system (not shown). For example, the imaging optical system is used to capture an image of the subject's face. For example, the imaging optical system may be composed of an imaging element and a lens. The anterior eye illumination unit 95 has an infrared illumination light source (not shown) disposed therein, and emits illumination light toward the left and right test eyes E for capturing an image of the anterior eye of the test eye E by the observation optical system 50 described below.

<Measurement section>
The measurement unit 7 includes a left eye measurement unit 7L and a right eye measurement unit 7R. In this embodiment, the left eye measurement unit 7L and the right eye measurement unit 7R are made of the same material. Of course, the left eye measurement unit 7L and the right eye measurement unit 7R may be made of at least a part of different materials. The measurement unit 7 has a pair of left and right optotype presenting optical systems, a pair of left and right subjective measurement units, and a pair of left and right objective measurement units. The optotype light beam and the measurement light beam from the measurement unit 7 are guided to the test eye E through the presentation window 3.

Figure 2 is a diagram showing the optical system arranged in the measurement unit 7. In Figure 2, the measurement unit 7 for the left eye 7L is taken as an example of the measurement unit 7. The measurement unit 7R for the right eye is omitted because it has the same configuration as the measurement unit 7L for the left eye. For example, the measurement unit 7L for the left eye includes an optotype presenting optical system 30, an objective measurement optical system 10, a subjective measurement optical system 25, a first alignment index optical system 55, a second alignment index optical system 40, an observation optical system 50, etc.

<Optotype presentation optical system>
The optotype presenting optical system 30 projects an optotype light beam toward the subject's eye E. For example, the optotype presenting optical system 30 includes a display 31, a projection lens 33, a projection lens 34, a reflecting mirror 36, an objective lens 37, a dichroic mirror 35, a dichroic mirror 29, and the like.

The display 31 displays a visual target (fixation target, test visual target, etc.). The visual target light beam emitted from the display 31 is projected onto the subject's eye E via the optical components from the projection lens 33 to the dichroic mirror 29 in order. The dichroic mirror 35 makes the optical path of the objective measurement optical system 10 and the optical path of the subjective measurement optical system 25 a common optical path. In other words, the dichroic mirror 35 makes the optical axis L1 of the objective measurement optical system 10 and the optical axis L2 of the subjective measurement optical system 25 coaxial. The dichroic mirror 29 is an optical path branching component. The dichroic mirror 29 reflects the visual target light beam from the visual target presenting optical system 30 and the measurement light beam from the projection optical system 10a described below, and guides them to the subject's eye E.

<Objective Measuring Optical System>
The objective measurement optical system 10 is used as a part of an objective measurement unit that objectively measures the optical characteristics of the subject's eye E. In this embodiment, an objective measurement unit that measures the ocular refractive power of the subject's eye E will be described as an example of the optical characteristics of the subject's eye E. For example, the objective measurement optical system 10 is composed of a projection optical system 10a and a light receiving optical system 10b.

The projection optical system 10a projects a spot-shaped measurement index onto the fundus of the test eye E through the center of the pupil of the test eye E. For example, the projection optical system 10a includes a light source 11, a relay lens 12, a hole mirror 13, a prism 15, an objective lens 14, a dichroic mirror 35, a dichroic mirror 29, etc.

The light source 11 emits a measurement light beam. The light source 11 is conjugate with the fundus of the test eye E. The hole portion of the hole mirror 13 is conjugate with the pupil of the test eye E. The prism 15 is a light beam deflection member. The prism 15 is disposed at a position that is not conjugate with the pupil of the test eye E, and decenters the measurement light beam passing through the prism 15 with respect to the optical axis L1. The prism 15 is rotated around the optical axis L1 by a drive unit (motor) 23.

The light receiving optical system 10b extracts the fundus reflected light beam reflected by the fundus of the test eye E in a ring shape through the pupil periphery of the test eye E. For example, the light receiving optical system 10b includes a dichroic mirror 29, a dichroic mirror 35, an objective lens 14, a prism 15, a hole mirror 13, a relay lens 16, a mirror 17, a light receiving aperture 18, a collimator lens 19, a ring lens 20, an image sensor 22, etc.

The ring lens 20 is composed of a lens portion formed in a ring shape and a light-shielding portion in which a light-shielding coating is applied to the area other than the lens portion. The ring lens 20 is in an optically conjugate positional relationship with the pupil of the subject's eye E. The light-receiving diaphragm 18 and the image sensor 22 are in a conjugate relationship with the fundus of the subject's eye E. The output from the image sensor 22 is input to the control unit 70.

In the above configuration, the measurement light beam emitted from the light source 11 passes through the optical components from the relay lens 12, the hole mirror 13, and the prism 15 to the dichroic mirror 29 in order to form a spot-shaped point light source image on the fundus of the test eye E. At this time, the pupil projection image (projected light beam on the pupil) of the hole part in the hole mirror 13 is rotated eccentrically at high speed by the prism 15 rotating around the optical axis. The point light source image projected on the fundus is reflected and scattered and emerges from the test eye E, reflected by the dichroic mirror 29 and the dichroic mirror 35, and collected by the objective lens 102. When it is collected again on the light receiving aperture 18 via the prism 15, the hole mirror 13, the relay lens 16, and the mirror 17, which rotate at high speed, it is imaged as a ring-shaped image on the image sensor 22 by the collimator lens 19 and the ring lens 20.

In this embodiment, the prism 15 is disposed on the common optical axis of the projection optical system 10a and the light receiving optical system 10b. For example, the measurement light beam from the projection optical system 10a passes through the prism 15 and enters the subject's eye E, and the fundus reflected light beam reflected by the fundus of the subject's eye E passes through the same prism 15, so that in the subsequent optical systems, the projection light beam and fundus reflected light beam (received light beam) are reverse scanned as if there was no decentering of the projection light beam and fundus reflected light beam (received light beam) on the pupil.

The ocular refractive power measurement optical system, which is an example of the objective measurement optical system 10, is not limited to the above as long as it is configured to obtain ocular refractive power. For example, it may be configured with a Shack-Hartmann sensor. For details of these, please refer to, for example, JP 2018-47049 A.

<Subjective Measuring Optical System>
The subjective measurement optical system 25 is used as a part of the subjective measurement unit that subjectively measures the optical characteristics of the subject's eye E. In this embodiment, a subjective measurement unit that measures the ocular refractive power of the subject's eye E is taken as an example of the optical characteristics of the subject's eye E. Note that the optical characteristics of the subject's eye E may be contrast sensitivity, binocular vision function (e.g., amount of heterophoria, stereoscopic vision function, etc.), etc., in addition to ocular refractive power. For example, the subjective measurement optical system 25 is composed of the optotype presenting optical system 30 and the correction optical system 60 described above.

<Corrective optical system>
The correction optical system 60 is disposed in the optical path of the optotype presenting optical system 30. The correction optical system 60 changes the optical characteristics of the optotype light beam emitted from the display 31. For example, the correction optical system 60 includes an astigmatism correction optical system 63, a drive mechanism 39 described later, and the like.

The astigmatism correction optical system 63 is used to correct the cylindrical power and astigmatism axis angle of the subject's eye E. The astigmatism correction optical system 63 is disposed between the projector lens 33 and the projector lens 34. The astigmatism correction optical system 63 is composed of two positive cylindrical lenses 61a and 61b with the same focal length. The cylindrical lenses 61a and 61b are each independently rotated around the optical axis L2 by the drive of the rotation mechanisms 62a and 62b.

In this embodiment, the astigmatism correcting optical system 63 is described using cylindrical lenses 61a and 61b as an example, but is not limited to this. The astigmatism correcting optical system 63 may be configured to correct the cylindrical power, astigmatism axis angle, etc. As an example, a corrective lens may be inserted and removed from the optical path of the optotype presenting optical system 30.

<Drive mechanism>
In this embodiment, the light source 11 and relay lens 12 included in the projection optical system 10a, the light receiving aperture 18, collimator lens 19, ring lens 20, and image sensor 22 included in the light receiving optical system 10b, and the display 31 included in the optotype presenting optical system 30 can be moved integrally in the optical axis direction by a drive mechanism 39. In other words, the display 31, the light source 11, the relay lens 12, the light receiving aperture 18, the collimator lens 19, the ring lens 20, and the image sensor 22 are synchronized as a drive unit 95, and are moved integrally by the drive mechanism 39. The drive mechanism 39 is composed of a motor and a slide mechanism. The movement position of the drive unit 95 moved by the drive mechanism 39 is detected by a potentiometer (not shown).

The drive mechanism 39 moves the display 31 in the direction of the optical axis L2 by moving the drive unit 95 in the direction of the optical axis. This allows the subject's eye E to be clouded in an objective measurement. In a subjective measurement, the presentation distance of the visual target relative to the subject's eye E can be optically changed to correct the spherical power of the subject's eye E. That is, the configuration that moves the display 31 in the direction of the optical axis L2 is used as a spherical correction optical system that corrects the spherical power of the subject's eye E, and the spherical power of the subject's eye E is corrected by changing the position of the display 31. Note that the configuration of the spherical correction optical system may be different from that of this embodiment. For example, the spherical power may be corrected by placing a large number of optical elements in the optical path. Also, for example, the spherical power may be corrected by placing a lens in the optical path and moving the lens in the optical axis direction.

The drive mechanism 39 also moves the light source 11, relay lens 12, and the image sensor 22 from the light receiving aperture 18 in the direction of the optical axis L1 by moving the drive unit 95 in the optical axis direction. As a result, the light source 11, the light receiving aperture 18, and the image sensor 22 are arranged so as to be optically conjugate with the fundus of the subject's eye E. Regardless of the movement of the drive unit 95, the hole mirror 13 and the ring lens 20 are arranged so as to be conjugate with the pupil of the subject's eye E at a constant magnification. For this reason, the fundus reflection light beam, which is the measurement light beam reflected from the projection optical system 10a, is always incident on the ring lens 20 of the light receiving optical system 10b as a parallel light beam, and a ring-shaped light beam of the same size as the ring lens 20 is imaged by the image sensor 22 in a focused state, regardless of the ocular refractive power of the subject's eye E.

<First alignment target optical system>
The first alignment target optical system 55 includes a light source 56 that emits near-infrared light, a collimator lens 57, and a half mirror 58. The light emitted from the light source 56 is converted into a substantially parallel beam by the collimator lens 57, and is reflected by the half mirror 58 to become coaxial with the optical axis L1 of the objective measurement optical system 10. Thereafter, the light from the light source 56 is reflected by the dichroic mirror 35 and the dichroic mirror 29, and projected onto the subject's eye E from the front direction of the subject's eye E.

<Second Alignment Target Optical System>
The second alignment index optical system 40 includes a projection optical system 40a and a detection optical system 40b. The projection optical system 40a includes a light source 41 that emits near-infrared light and a collimator lens 42, and projects index light from an oblique direction toward the cornea of the subject's eye E. The optical axis of the detection optical system 40b is arranged symmetrically with the optical axis of the projection optical system 40a with respect to the optical axis L3 of the observation optical system 50. The detection optical system 40b includes a lens 46, a condenser lens 47, and a position detection element 48. The illumination light projected by the light source 41 is reflected by the cornea of the subject's eye E to form an index image (corneal reflection bright spot), which is a virtual image of the light source 41. The light of the index image is incident on the position detection element 48 via the lens 46 and the condenser lens 47. The position of the index image on the position detection element 48 changes depending on the position of the subject's eye E in the Z direction. The output signal of the position detection element 48 is output to the control unit 70, and the alignment state of the subject's eye E in the Z direction is detected by the control unit 70.

<Observation optical system>
The observation optical system (imaging optical system) 50 includes a dichroic mirror 29, an objective lens 53, an imaging lens 51, an imaging element 52, etc. The dichroic mirror 29 transmits anterior segment observation light and alignment light. The imaging element 52 has an imaging surface arranged at a position conjugate with the anterior segment of the subject's eye E. The output from the imaging element 52 is input to the control unit 70. As a result, an anterior segment image of the subject's eye E is captured by the imaging element 52 and displayed on the monitor 6a.

The observation optical system 50 also serves as an optical system that detects an index image formed on the cornea of the test eye E by the first alignment index optical system 55. That is, light from the light source 56 of the first alignment index optical system 55 is reflected by the cornea of the test eye E to form an index image (corneal reflection bright spot), which is a virtual image of the light source 56, and the index image is received by the image sensor 52. Then, the position of the index image is detected by the control unit 70 based on the output signal of the image sensor 52, and the alignment state of the test eye E in the XY directions is detected.

<Internal configuration of the optometry device>
The internal configuration of the optometry apparatus 1 will be described. Fig. 3 is a schematic diagram of the inside of the optometry apparatus 1 as viewed from the front. Fig. 4 is a schematic diagram of the inside of the optometry apparatus 1 as viewed from the side. Fig. 5 is a schematic diagram of the inside of the optometry apparatus 1 as viewed from above. For ease of explanation, Figs. 4 and 5 only show the optical axis of the left eye measurement unit 7L.

In addition to the measurement unit 7, the eye examination device 1 includes a deflection mirror 81, a drive mechanism 82, a drive unit 83, a reflection mirror 84, a concave mirror 85, etc., which are examples of light deflection members shared by the subjective measurement unit and the objective measurement unit. Note that the subjective measurement unit and the objective measurement unit are not limited to this configuration. For example, a configuration without a reflection mirror 84 is also possible. In this case, the visual target light beam from the measurement unit 7 may be irradiated from an oblique direction with respect to the optical axis L of the concave mirror 85 after passing through the deflection mirror 81. Also, for example, a configuration with a half mirror may be used. In this case, the visual target light beam from the measurement unit 7 may be irradiated from an oblique direction with respect to the optical axis L of the concave mirror 85 via the half mirror, and the reflected light beam may be guided to the subject's eye E.

The optometry device 1 has a left eye drive unit 9L and a right eye drive unit 9R, and can move the left eye measurement unit 7L and the right eye measurement unit 7R in the X direction (horizontal direction). For example, by moving the left eye measurement unit 7L and the right eye measurement unit 7R in the X direction, the distance between the measurement unit 7 and a deflection mirror 81 described below changes, and the presentation position of the visual target light beam from the measurement unit 7 in the Z direction (front-back direction relative to the subject) is changed. As a result, the visual target light beam corrected by the correction optical system 60 is guided to the subject's eye E, and the measurement unit 7 is adjusted in the Z direction so that an image of the visual target light beam corrected by the correction optical system 60 is formed on the fundus of the subject's eye E.

For example, the deflection mirror 81 has a pair of right-eye deflection mirror 81R and left-eye deflection mirror 81L, which are provided on the left and right sides. For example, the deflection mirror 81 is arranged between the measurement unit 7 and the test eye E. In this embodiment, the deflection mirror 81R is arranged between the measurement unit 7R and the test eye ER, and the deflection mirror 81L is arranged between the measurement unit 7L and the test eye EL. That is, the deflection mirror 81 is arranged in the shared optical path of the objective optical system 10 and the optotype presenting optical system 30 of the measurement unit 7. The deflection mirror 81 is also arranged in the optical path of the subjective measurement optical system 25. It is preferable that the deflection mirror 81 is arranged at the pupil conjugate position.

For example, the left eye deflection mirror 81L reflects the light beam projected from the left eye measurement unit 7L and guides it to the left eye EL. Also, for example, the left eye deflection mirror 81L reflects the fundus reflection light beam from the left eye EL and guides it to the left eye measurement unit 7L. For example, the right eye deflection mirror 81R reflects the light beam projected from the right eye measurement unit 7R and guides it to the right eye ER. Also, for example, the right eye deflection mirror 81R reflects the fundus reflection light beam from the right eye ER and guides it to the right eye measurement unit 7R. In this embodiment, a configuration using the deflection mirror 81 as a deflection member that reflects and guides the light beam projected from the measurement unit 7 to the subject eye E is described as an example, but is not limited to this. The deflection member may be, for example, a prism, a lens, etc., as long as it can reflect and guide the light beam projected from the measurement unit 7 to the subject eye E.

In addition, in this embodiment, the deflection mirrors 81 (deflection mirror for the left eye 81L, deflection mirror for the right eye 81R) also function as a prism-imparting unit that imparts an arbitrary prism amount (prism power) to the test eye E. That is, instead of placing an actual rotary prism in front of the test eye E (the optical path of the subjective measurement optical system 25 and the objective measurement optical system), the deflection mirror 81 is driven to change the direction of the visual target light beam heading toward the test eye E, thereby imparting an arbitrary prism amount to the test eye E.

The prism imparting unit that imparts an arbitrary prism amount to the subject's eye E may be configured to use the display 31 of the optotype presenting optical system 30 and shift the position of the optotype displayed on the screen in the X direction.

For example, the drive mechanism 82 is composed of a motor (drive unit) and the like. For example, the drive mechanism 82 has a drive mechanism 82L for driving the left-eye deflection mirror 81L and a drive mechanism 82R for driving the right-eye deflection mirror 81R. For example, the deflection mirror 81 rotates when driven by the drive mechanism 82. For example, the drive mechanism 82 rotates the deflection mirror 81 about a horizontal rotation axis (X direction) and a vertical rotation axis (Y direction). That is, the drive mechanism 82 rotates the deflection mirror 81 in the XY directions. Note that the rotation of the deflection mirror 81 may be either the horizontal direction or the vertical direction.

For example, the drive unit 83 is composed of a motor or the like. For example, the drive unit 83 has a drive unit 83L for driving the left eye deflection mirror 81L and a drive unit 83R for driving the right eye deflection mirror 81R. For example, the deflection mirror 81 moves in the X direction when driven by the drive unit 83. For example, by moving the left eye deflection mirror 81L and the right eye deflection mirror 81R, the distance between the left eye deflection mirror 81L and the right eye deflection mirror 81R is changed, and the distance in the X direction between the left eye optical path and the right eye optical path can be changed according to the interpupillary distance of the test eye E.

For example, multiple deflection mirrors 81 may be provided in each of the left eye optical path and the right eye optical path. For example, two deflection mirrors may be provided in each of the left eye optical path and the right eye optical path (for example, two deflection mirrors may be provided in the left eye optical path, etc.). In this case, one deflection mirror may be rotated in the X direction, and the other deflection mirror may be rotated in the Y direction. For example, by rotating and moving the deflection mirror 81, the apparent light beam for forming an image of the visual target light beam in front of the subject's eye E can be deflected, and the position at which the image of the visual target light beam is formed can be optically corrected.

For example, the concave mirror 85 is shared by the left eye measurement unit 7L and the right eye measurement unit 7R. For example, the concave mirror 85 is shared by the left eye optical path including the left eye correction optical system and the right eye optical path including the right eye correction optical system. That is, the concave mirror 85 is disposed at a position where it passes through both the left eye optical path including the left eye correction optical system and the right eye optical path including the right eye correction optical system. Of course, the concave mirror 85 does not have to be configured to be shared by the left eye optical path and the right eye optical path. For example, a concave mirror may be provided in each of the left eye optical path including the left eye correction optical system and the right eye optical path including the right eye correction optical system. For example, the concave mirror 85 guides the visual target light beam that has passed through the correction optical system 60 to the subject's eye E, and forms an image of the visual target light beam that has passed through the correction optical system 60 in front of the subject's eye E.

<Optical path of subjective measurement unit>
The optical path of the subjective measurement unit will be described by taking the optical path for the left eye as an example. The optical path for the right eye has the same configuration as the optical path for the left eye. For example, in the subjective measurement unit for the left eye, the visual target light beam emitted from the display 31 in the subjective measurement optical system 25 enters the astigmatism correction optical system 63 through the projection lens 33, and when it passes through the astigmatism correction optical system 63, it is guided from the left eye measurement unit 7L to the left eye deflection mirror 81L via the projection lens 34, the reflection mirror 36, the objective lens 37, the dichroic mirror 35, and the dichroic mirror 29. The visual target light beam reflected by the left eye deflection mirror 81L is reflected by the reflection mirror 84 toward the concave mirror 85. The visual target light beam emitted from the display 31 reaches the left eye EL via each optical member in this way.

As a result, an image of the visual target light beam corrected by the correction optical system 60 is formed on the fundus of the left eye EL, based on the eyeglass wearing position of the left eye EL (for example, approximately 12 mm from the corneal apex position). Therefore, adjustment of the spherical power by the spherical power correction optical system (in this embodiment, driving of the drive mechanism 39) is performed in front of the eye, which is equivalent to placing the astigmatism correction optical system 63 in front of the eye. The subject can collimate the image of the visual target light beam optically formed in front of the eye at a predetermined test distance optically via the concave mirror 85 in a natural state.

<Optical path of objective measurement unit>
The optical path of the objective measurement section will be described. In the following description, the optical path for the left eye will be taken as an example, but the optical path for the right eye has the same configuration as the optical path for the left eye. For example, in the objective measurement section for the left eye, the measurement light emitted from the light source 11 of the projection optical system 10a in the objective measurement optical system 10 passes through the relay lens 12 and the dichroic mirror 29, and is projected from the measurement section for the left eye 7L toward the deflection mirror 81L for the left eye. The measurement light emitted from the measurement section for the left eye 7L and reflected by the deflection mirror 81 for the left eye is reflected by the reflection mirror 84 toward the concave mirror 85. The measurement light reflected by the concave mirror reaches the left eye EL and forms a spot-shaped point light source image on the fundus of the left eye EL. At this time, the prism 15 rotating around the optical axis causes the pupil projection image (projection light beam on the pupil) of the hole part of the hole mirror 13 to rotate eccentrically at high speed.

The light of the point light source image formed on the fundus of the left eye EL is reflected and scattered, exits the test eye E, travels along the optical path through which the measurement light passed, is collected by the objective lens 14, and reaches the prism 15, the hole mirror 13, the relay lens 16, and the mirror 17. The light reflected by the mirror 17 is collected again on the opening of the light receiving diaphragm 18, and made into a substantially parallel beam (in the case of an emmetropic eye) by the collimator lens 19. It is extracted as a ring-shaped beam by the ring lens 20, and is received by the image sensor 22 as a ring image. By analyzing the received ring image, the optical characteristics of the test eye E can be objectively measured.

<Control Unit>
Fig. 6 is a diagram showing a control system of the optometry apparatus 1. For example, the control unit 70 is electrically connected to various components (electrical components shown in Fig. 2) such as the monitor 6a, a memory 75 (e.g., a non-volatile memory) which is an example of a storage means, the light source 11, the image sensor 22, the display 31, the image sensor 52, etc., which are provided in the measurement unit 7. In addition, for example, the control unit 70 is electrically connected to driving units (not shown) provided in the driving unit 9, the driving mechanism 39, the driving unit 83, etc.

For example, the control unit 70 includes a CPU (processor), a RAM, a ROM, etc. For example, the CPU controls each component in the eye examination device 1. For example, the RAM temporarily stores various information. For example, the ROM stores various programs, optotypes, initial values, etc. for controlling the operation of the eye examination device 1. Note that the control unit 70 may be composed of multiple control units (i.e., multiple processors).

For example, the memory 75 is a non-transient storage medium that can retain its stored contents even if the power supply is cut off. For example, a hard disk drive, a flash ROM, a USB memory, etc. can be used as the memory 75. For example, the memory 75 stores a control program for controlling the objective measurement unit and the subjective measurement unit.

<Control operation>
The operation of the optometry apparatus 1 having the above-mentioned configuration will be described below. For example, the case where the subject has heterophoria will be described below.

The subject places their forehead on the forehead rest 4 and observes the presentation window 3. Once the subject is ready for the examination, the examiner operates the switch unit 6b of the controller 6 to input a selection signal for a visual target (fixation target) for fixating the subject's eye E. The control unit 70 causes the displays 31 provided on each of the left eye measurement unit 7L and the right eye measurement unit 7R to display the same visual target based on the visual target selection signal. A visual target is presented to each of the subject's eyes (left eye EL and right eye ER), but by presenting the same visual target, the subject recognizes it as a single visual target with both eyes.

<Alignment of the measurement unit with respect to the subject's eye>
Next, the examiner inputs a start signal for aligning the left eye measurement unit 7L and the right eye measurement unit 7R to the left eye EL and right eye ER of the subject, respectively, by the switch unit 6b. An index by the first alignment index optical system 55 and an index by the second alignment index optical system 40 are projected onto the left eye EL and right eye ER, respectively. The index by the first alignment index optical system 55 is received by the image sensor 52, and the alignment state of the measurement unit 7 in the XY direction is detected based on the output signal from the image sensor 52. The index by the second alignment index optical system 40 is received by the position detection element 48, and the alignment state of the measurement unit 7 in the Z direction is detected based on the output signal from the position detection element 48. Based on the alignment detection in the XY and Z directions, the control unit 70 controls the driving of the drive unit 9 (9L, 9R), drive mechanism 82 (82L, 82R), and drive unit 83 (83L, 83R), moves the measurement unit 7 (7L, 7R) in the XY and Z directions, and completes the alignment with the test eye E.

<Measurement of strabismus (eye position) of the subject's eye>
For example, the subject's eye E is placed in a covered state and a non-covered state, and an anterior eye image is obtained in each state, thereby performing a strabismus test. For example, a cover-uncover test may be performed on the subject's eye E as one of the strabismus tests. The cover-uncover test is a test method in which a cover covering one eye's field of vision is removed and the eye movement at that time is confirmed. The subject's eye E placed in a covered state is in a fusion-free eye position (the eye position when fusion is removed while the subject is fixating with both eyes). In other words, the subject's eye E does not need to look at the visual target (object), so it moves to a comfortable position without convergence.

In this embodiment, a strabismus test is performed by presenting a visual target to one eye and switching between presenting and not presenting the visual target to the other eye. The visual target is presented by displaying a predetermined identical visual target on the display 31 of the visual target presenting optical system 30 arranged in each of the left eye measurement unit 7L and the right eye measurement unit 7R. For example, the presentation and non-presentation of the visual target is switched between a state in which the visual target is displayed on the display 31 and a state in which the display is turned off. The presence or absence of strabismus is measured by detecting eye movement at the time of switching from a state in which the visual target is presented to a state in which it is not presented for one eye, the direction of the strabismus is measured based on the direction of the eye movement, and the amount of strabismus is measured based on the amount of the eye movement. In the following description, the left eye EL is the measured eye and the right eye ER is the non-measured eye.

When the alignment of the subject's eye E is complete, the examiner operates the switch unit 6b and selects the switch to start measuring the strabismus of the subject's eye E. The control unit 70 turns on the light source 56 of the first alignment index optical system 55 in response to the input signal from the switch unit 6b. This causes a Purkinje image to be formed on the cornea of the subject's eye E by the corneal reflection of the index light emitted from the light source 56.

In addition, the control unit 70 displays the optotype for the left eye on the display 31 of the left eye measurement unit 7L (hereinafter, display 31L) and displays the optotype for the right eye on the display 31 of the right eye measurement unit 7R in response to an input signal from the switch unit 6b. For example, at this time, the lines of sight of the left eye EL and the right eye ER are aligned with their respective optical axes L1 (L2, L3). Next, the control unit 70 turns off the display 31L and makes the optotype for the left eye non-presented. If the subject's eye has strabismus, the subject's eye will be in a fusion-free position in the non-presentation state of the optotype, and the line of sight of the left eye EL, which is the measurement eye, will deviate from the optical axis L1 and face in the direction of the strabismus. An image of the anterior segment at this time is acquired by the imaging element 52 of the observation optical system 50.

The configuration for switching between the presentation state and non-presentation state of the optotype for the subject's eye E may be a configuration in which a visible light blocking member (e.g., an IR filter, etc.) 111 is inserted and removed in front of the subject's eye E, as shown in FIG. 5. When the presentation of the optotype is switched to the non-presentation state, the visible light blocking member 111 is inserted in front of the subject's eye E. The visible light blocking member 111 transmits anterior segment imaging light (in this embodiment, near-infrared light, which is invisible light) for imaging the anterior segment with the imaging element 52, and blocks visible light presenting the optotype. In this case, even if the optotype for the subject's eye E is not presented, the imaging element 52 can properly image the anterior segment of the subject's eye E before and after switching the presentation of the optotype.

Figure 7 is an example of an anterior segment image 100 of the subject's eye E acquired by the image sensor 52. Figure 7 shows an example in which the left eye EL has exophoria. For example, the anterior segment image 100 shows the pupil P of the subject's eye E and an index S, which is a Purkinje image formed by the first alignment index optical system 55. The index S, which is a Purkinje image, indicates the position of the corneal apex. The control unit 70 analyzes and processes the anterior segment image 100, detects the pupil P based on the level of the luminance signal (rising and falling edges, etc.), and obtains the position coordinates of the pupil center Pc by determining the center of the pupil P. The control unit 70 also analyzes and processes the anterior segment image 100 to obtain the position coordinates of the index S. The control unit 70 then detects the direction of the strabismus (exophoria, esophoria, superphoria, hypophoria, and a combination of these) based on the direction in which the index S is located relative to the pupil center Pc. The control unit 70 also detects the amount of heterophoria based on the amount of deviation Δd of the index S from the pupil center Pc. Since the amount of heterophoria is the amount of deviation in eye position, the control unit 70 determines the amount of prism (prism power) to be applied to the subject's eye E based on the amount of deviation in eye position. The measurement results of heterophoria are displayed on the monitor 6a.

Obtaining eye characteristic information by measuring eye refractive power over time
If the heterophoria test reveals that the subject has heterophoria, the procedure moves to objective measurement of the ocular refractive power over time (change in ocular refractive power over time) while changing the amount of prism applied to the subject's eye E. This measurement is performed in a binocular vision state, with a test target presented to both the left and right eyes of the subject.

For example, the amount of prism applied to the subject's eye E is set based on the amount of deviation in eye position during the strabismus test, and is changed to at least two states in which the prism amount is changed. For example, the measurement includes a state in which no prism amount is applied and a state in which the prism amount is a fusion-free eye position, and is performed in four states in which the prism amount is changed at equal intervals between them. For example, in the following, it is assumed that the state of the fusion-free eye position is 15 prism amounts, and the first measurement is performed in a state in which 15 prism amounts are applied, the second in a state in which 10 prism amounts are applied, the third in a state in which 5 prism amounts are applied, and the fourth in a state in which zero prism amount is applied (a state in which no prism amount is applied to the subject's eye).

The prism amount for at least two states when measuring the ocular refractive power of the subject's eye E may be arbitrarily set by the subject or examiner. For example, the monitor 6a displays a prism amount value corresponding to the amount of deviation of the eye position in a strabismus test. The subject or examiner may refer to this value and arbitrarily set multiple stages of prism amount by operating the switch unit 6b. In this case, the controller 6 (monitor 6a and switch unit 6b) functions as an example of a prism amount setting means.

The examiner operates the switch unit 6b and inputs a measurement start signal to perform objective measurement of eye refractive power over time. For example, the control unit 70 moves the deflection mirror 81L to the left eye EL, which is the measurement eye in the strabismus test, based on the amount of deviation of the eye position. For example, in the first measurement, the control unit 70 moves the deflection mirror 81L by an amount equivalent to 15 prisms. Then, the control unit 70 performs eye refractive power measurement using the objective measurement optical system 10 with 15 prism amounts applied to the left eye EL. In the eye refractive power measurement, the same optotype is presented to the left eye EL and the right eye ER. In addition, for the time-dependent measurement, the control unit 70 continuously performs eye refractive power measurement of both the left and right eyes for a certain time T (for example, 5 seconds) with a prism amount applied to the left eye EL. The measurement results of eye refractive power over time are obtained based on the output from the image sensor 22 and stored in the memory 75.

Similarly, the control unit 70 continuously measures the eye refractive power for a certain period of time with a prism amount of 10 applied in the second measurement, with a prism amount of 5 applied in the third measurement, and with a prism amount of zero applied in the fourth measurement. The measurement results of the eye refractive power over time in each prism state are stored in the memory 75.

In addition, with regard to the provision of a prism amount in the fusion-free eye position, the deflection mirror 81L is moved to provide a prism amount to the left eye EL in the above description, but the following may also be done. For example, as in the above-mentioned strabismus test, the optotype for the left eye EL is not presented (the display 31L is turned off, or the visible light blocking member 111 is placed in front of the eye). This places the left eye EL in a fusion-free eye position, and the eye moves in the strabismus direction. In this state, eye alignment of the measurement unit 7L is performed based on the indexes from the first alignment index optical system 55 and the second alignment index optical system 40, and the eye refractive power of the left eye EL is measured. Even in such an eye refractive power measurement in which the optotype for the left eye EL is not presented, it is equivalent to a state in which a prism amount is provided to the test eye, and is included in the provision of a prism amount in this embodiment.

When the eye refractive power measurement at different prism amount conditions is completed, the control unit 70 analyzes the eye refractive power at each prism amount condition and obtains characteristic information of the subject's eye.

Figure 8 is a schematic example showing the results of eye refractive power measurement over time for the left eye EL to which a prism amount has been applied. In Figures 8(a) and 8(b), the horizontal axis shows the elapsed time, and the vertical axis shows the change in eye refractive power. Figure 8(a) is an example when, for example, 10 prisms are applied to the eye. Figure 8(b) is an example when, for example, zero prism amount is applied to the eye. In subjects with strabismus, when the amount of prism applied to the eye is small, some can fuse the visual target by the convergence force of their own eyes in binocular vision. However, convergence of the eyes is accompanied by physiological eye accommodation, which puts a strain on the refractive state of the eyes. For this reason, in FIG. 8(a), which shows an example in which the eye is in or close to the fusion-free position by applying a prism amount to the eye, the amplitude of the temporal change in ocular refractive power is large and the period tends to be short in FIG. 8(b), which shows an example in which a small amount of prism is applied to the eye. Therefore, by analyzing the change in ocular refractive power over time when the amount of prism applied to the eye is changed, it is possible to provide useful information for appropriately prescribing corrective lenses to the subject. For example, the characteristic information of the eye that appears in a subject with heterophoria can include at least one of the period, amplitude, and variance of the change in ocular refractive power over time, and the frequency of occurrence of high frequency components (hereinafter referred to as HFC).

The HFC can be analyzed using the technology described in JP 2003-70740 A, and can be calculated, for example, as follows. First, a frequency analysis is performed on the eye refractive power change data using a fast Fourier transform (FFT) to calculate a power spectrum. The calculated power spectrum is converted to common logarithms for analysis. The average power spectrum (dB) of a specified high frequency component (for example, the 1.0 to 2.3 Hz range) is calculated from this power spectrum, and the frequency of occurrence of the high frequency component is evaluated.

Figure 9 shows an example of the measurement results and characteristic information of the ocular refractive power (ocular characteristic information appearing in a subject with strabismus) output in correspondence with the amount of prism applied to the left eye EL. For example, the output of the measurement results and characteristic information is displayed on the monitor 6a. The output may be printed on a printer or transferred to another device. Note that the measurement results of the right eye ER are not shown in the figure.

In FIG. 9, display field 201 displays the prism amount at which the eye refractive power measurement was performed, display field 202 displays the measurement result of the eye refractive power, display field 203 displays the period of the eye refractive power change, display field 204 displays the variance of the eye refractive power change, display field 205 displays the period of the eye refractive power change, and display field 206 displays the HFC (frequency of occurrence of high frequency components) of the eye refractive power change. Note that the eye refractive power, amplitude, variance, period, and HFC values corresponding to each prism amount are displayed as average values or representative values of measurements over time.

In addition, in outputting the measurement results of the eye refractive power and the characteristic information corresponding to each prism amount, the control unit 70 may determine the level of the characteristic information (the level of the characteristic information) in each state in which the prism amount is changed, and output the determination results together. For example, a "◯" mark 211, which is an example of identification information for distinguishing the characteristic information from other information, is attached to the minimum value of the characteristic information in each prism state. In addition, a "□" mark 212, which is an example of identification information for distinguishing the characteristic information from other information, is attached to the maximum value of the characteristic information in each prism state. By attaching the "◯" mark 211 to the measurement results of the eye refractive power and the output of the characteristic information, the examiner can easily understand the load state of the test eye E caused by the convergence of the test eye, and can determine the appropriate prism amount and refractive power when prescribing a corrective lens for the test person.

In addition, the high and low characteristic information values in each prism state may be indicated by at least two levels of color coding. For example, the lowest characteristic information value in each prism state may be displayed in blue, the highest characteristic information value in each prism state may be displayed in red, and the rest in black. In addition, the identification information may be displayed by level values (e.g., level 1, level 2, level 3) that indicate the high and low characteristic information.

In addition, the control unit 70 may determine whether the ocular refractive power has changed by a predetermined power step (e.g., 0.25 diopters) or more due to the difference in the amount of prism applied to the eye (i.e., the difference in eye position), and the result may be output so that the examiner can recognize it. For example, in the example of FIG. 9, when there is a change of 0.25 diopters or more (a change in the direction of weakening the power), which is a predetermined power step, compared to the ocular refractive power in the state of zero prism amount, a mark 213 is attached to distinguish it from others. This makes it possible to clearly show the application of a prism amount that is advantageous as a change in ocular refractive power. In addition, when the change in ocular refractive power is less than the predetermined power step compared to the ocular refractive power in the state of zero prism amount, there is little significant difference in ocular refractive power even if a prism amount is applied to the eye, so the examiner can use this as a reference for determining whether or not a prism amount is necessary when prescribing a corrective lens.

Obtaining eye characteristic information by measuring minute displacements in eye movement
In order to obtain eye characteristic information, minute displacements of eye movement over time may be measured in a state where the prism amount used to measure the eye refractive power is applied to the subject's eye E. For example, the minute displacements of eye movement can be obtained as minute displacements of eye position. For example, the minute displacements of eye position can be obtained by analyzing an anterior eye image 100 of the subject's eye E acquired by the image sensor 52 as in FIG. 7 and measuring the displacements of the pupil center Pc or the index S (corneal center) over time in the anterior eye image 100.

In addition, the measurement of minute displacement of eye position over time can be performed in parallel with the eye refractive power measurement over time described above. That is, in the eye refractive power measurement over time in the previous example, the control unit 70 obtains information on the displacement of the pupil center Pc or the index S over time based on the anterior eye image acquired by the image sensor 52 in parallel with the acquisition of the measurement results of the eye refractive power measurement in a state in which 15 prism amounts, 10 prism amounts, 5 prism amounts, and zero prism amounts are applied to the left eye EL for a certain period of time T. For example, this displacement information may be obtained as a displacement in the heterophoria direction obtained in the heterophoria test. Note that the measurement of minute displacement of eye position over time may be performed separately from the eye refractive power measurement over time. The measurement results of minute displacement of eye position over time in each prism state are stored in the memory 75.

Figure 10 is a schematic example of the measurement results of the minute displacement of eye position. In Figures 10(a) and 10(b), the horizontal axis represents the elapsed time, and the vertical axis represents the change in eye position. Figure 10(a) is an example of a case where the load on the test eye E due to convergence is small (when the test eye E is in or close to the fusion-free eye position), for example, when 10 prisms are applied to the eye. On the other hand, Figure 10(b) is an example of a case where the load on the test eye E due to convergence is large, for example, when a prism amount of zero is applied to the eye. Compared to Figure 10(a), in Figure 10(b) where the load on the eye due to convergence is large, the amplitude of the displacement of the eye position (eyeball) tends to be large and the period of the displacement tends to be short. Therefore, by analyzing the change in eye position (eyeball) over time when the amount of prism applied to the eye is changed, useful information can be provided for appropriately prescribing corrective lenses to the subject. For example, the eye characteristic information appearing in a strabismus subject may include at least one of the period, amplitude, variance, and HFC of the change in eye position (eyeball) over time.

Figure 11 shows an example of characteristic information (eye characteristic information appearing in a subject with strabismus) that is output as a measurement result of minute displacement of eye position (eyeball) corresponding to the amount of prism applied to the left eye EL. For example, the output of the characteristic information is displayed on the monitor 6a. The output may be printed on a printer or transferred to another device. Note that the measurement results of the right eye ER are not shown in the figure.

In FIG. 11, display field 221 displays the amount of prism applied to the eye, display field 223 displays the amplitude of the eye position displacement, display field 224 displays the variance of the eye position displacement, display field 225 displays the period of the eye position displacement, and display field 226 displays the HFC (frequency of occurrence of high frequency components) of the eye position displacement. The amplitude, variance, period, and HFC values corresponding to each prism amount are displayed as average values or representative values measured over time. Note that specific examples of values are omitted in FIG. 11.

In addition, in outputting characteristic information relating to minute displacements of eye movement corresponding to each prism amount, similar to the case of eye refractive power over time, the control unit 70 may determine the level of the characteristic information (the level of the characteristic information) in each state in which the application of the prism amount has been changed, and output the determination results together. For example, as in FIG. 9, a "circle" mark 211, which is an example of identification information for distinguishing the characteristic information from other information, is attached to the minimum value of the characteristic information in each prism state. Furthermore, a "square" mark 212, which is an example of identification information for distinguishing the characteristic information from other information, is attached to the maximum value of the characteristic information in each prism state.

Also, as in FIG. 9, when the eye refractive power is displayed and there is a change of 0.25 diopters or more (a change in the direction of weakening the power) compared to the eye refractive power when the prism amount is zero, a mark 213 is affixed to distinguish it from others.

Figure 12 shows an example of characteristic information on eye position displacement, where a frequency analysis is performed on the eye position displacement relative to the amount of prism applied to the eye, and the result is then graphed and output. It can be seen that with a prism amount of 10, there is a high frequency of low frequencies, but with a prism amount of zero, there is a tendency for the frequency of high frequencies to be high. This makes it clear visually that a prism amount of 10 places less strain on the eyes than a prism amount of zero. Note that while Figure 12 shows graphs for a prism amount of 10 and zero as examples, graphs for other prism amounts may also be output.

The output shown in Figures 11 and 12 makes it easier for the examiner to understand the load state of the subject's eye E in each prism state, enabling him or her to determine the appropriate prism amount when prescribing corrective lenses for the subject.

<Measurement of eye refractive power with continuous change in prism amount>
The above describes an example in which the amount of prism applied to the test eye E is changed to at least two states and the eye refractive power over time is measured for each state, but the eye refractive power may also be measured continuously while the amount of prism is continuously changed.

When the examiner operates the switch unit 6b and inputs a measurement start signal for performing eye refractive power measurement with continuously changing prism amount, the control unit 70 drives the deflection mirror 81L, which is an example of a prism amount changing means, based on the prism amount in the strabismus test (or the prism amount set by the examiner), and gives, for example, a prism amount of 15 to the left eye EL. At this time, the same optotype is displayed on the display 31 of the left and right optotype presenting optical systems 30, and the same optotype is presented to both eyes of the examinee. Then, the control unit 70 performs eye refractive power measurement using the objective measurement optical system 10 while continuously changing the prism amount given to the left eye EL so that the prism amount gradually decreases, and continuously obtains measurement results of eye refractive power corresponding to the prism amount given to the left eye EL. This measurement makes it possible to obtain in detail the relationship between the eye refractive power and the prism amount given to the test eye E in a short measurement time.

Figure 13 is an example of the output of the measurement results of the above-mentioned continuous measurements. For example, a graphic graph 241 of the eye refractive power (refractive power) versus the amount of prism is displayed on the screen of monitor 6a. For example, in Figure 13, when the amount of prism is specified by moving cursor 242 on the screen, the eye refractive power for that amount of prism is displayed in display field 243. This type of output makes it possible to provide the examiner with information to prescribe a more appropriate corrective lens.

9, the control unit 70 may determine whether the ocular refractive power has changed by a predetermined power step (for example, 0.25 diopters) or more depending on the difference in the amount of prism applied to the eye, and the result may be output so that the examiner can recognize it. For example, in the example of FIG. 13, hatching marks 245 are shown in the area of the prism amount showing a change of 0.25 diopters or more (change in the direction of weakening the power) compared to the ocular refractive power with zero prism amount. If the change in ocular refractive power is less than the predetermined power step (less than 0.25 diopters), there is little significant difference in ocular refractive power even if a prism amount is applied to the eye, so there are some subjects for whom a prism amount prescription is not necessary. In this case, it is possible to prescribe glasses in a normal examination that does not consider heterophoria without performing the time-dependent ocular refractive power measurement or the measurement of minute displacement of eye movement described above, and the examination time can be shortened. In other words, the measurement of ocular refractive power with a continuously changed prism amount can be used as screening.

The graph showing the relationship between the prism amount applied to the eye and the ocular refractive power in FIG. 13 may also be output when outputting the measurement results of the above-mentioned time-dependent ocular refractive power measurement. For example, in the time-dependent ocular refractive power measurement, the measurement is performed by applying a stepwise prism amount, but the relationship between the prism amount for which no measurement has been performed and the ocular refractive power can be interpolated based on the results of the measurement. That is, the control unit 70 outputs a graph such as that shown in FIG. 13 by interpolating the relationship between the prism amount for which no measurement of ocular refractive power has been performed and the ocular refractive power from the results of the measurement of ocular refractive power. Then, based on the interpolation results obtained, the control unit 70 obtains the prism amount corresponding to the ocular refractive power that has changed by more than a predetermined power step, and outputs the result (for example, by displaying the hatched mark 245).

In addition, the control unit 70 may determine the correspondence relationship (e.g., a function, table, or graph) between the prism amount imparted to the test eye and the ocular refractive power based on the ocular refractive power obtained in each prism state, instead of by interpolation. Then, based on the determined correspondence relationship between the prism amount and the ocular refractive power, the control unit 70 determines the prism amount corresponding to the ocular refractive power that has changed by a predetermined power step or more from the ocular refractive power in a state of zero prism amount, and outputs the result as shown in FIG. 13.

<Selection of objective eye refraction measurement in binocular or monocular vision>
In the above description, if the subject has heterophoria as a result of the measurement of the heterophoria (eye position), the eye refraction measurement is performed in the binocular vision state. However, the eye refraction measurement in the binocular vision state and the eye refraction measurement in the monocular vision state may be selected based on the measurement result of the heterophoria (eye position) (amount of deviation of the eye position). For example, if the subject does not have heterophoria (amount of deviation of the eye position is less than a predetermined amount), prescription of the prism amount is not necessary, so the control unit 70 automatically selects the mode of the monocular measurement and performs the eye refraction measurement of each of the left and right eyes in the monocular vision state. Alternatively, the measurement result of the deviation of the eye position is displayed, and the examiner inputs a selection signal for whether or not to perform the monocular measurement by the controller 6, and performs the left and right eye refraction measurement in the monocular vision state. Also, for example, the result of the eye refraction measurement in the binocular vision state and the result of the eye refraction measurement in the monocular vision state are output in a comparable manner (for example, displayed on the monitor 6a), thereby providing reference information for making a prism prescription.

<Test to check the subject's vision>
Once a series of measurements has been completed while varying the amount of prism applied to the eye as described above, the subjective measurement optical system 25 is used to apply/not apply (insert/not insert) each prism amount and then the test is moved on to check the vision.

The examiner operates the switch unit 6b to set the subjective test mode. The subjective test may be performed for each eye. For example, the examiner determines the amount of prism to be applied to the eye and the correction power for driving the correction optical system 60 based on the result of the relationship between the prism amount and the eye refractive power in the objective measurement, and operates the switch unit 6b to input the prism amount and the correction power. For example, based on the previous objective eye refractive power measurement, the examiner sets the S value (spherical power) of the correction power for the left eye EL to minus 3.75 D (diopters), and sets the C value (abnormal power) and A value (cylindrical axis angle) of the correction power to the values of the result of the objective refractive power measurement. For example, the examiner sets the prism amount to 10 prism amount, which is close to the fusion removal eye position. The control unit 70 drives the correction optical system 60 and the deflection mirror 81 based on the setting information. As the test optotype, a visual acuity value optotype (for example, an optotype with a visual acuity value of 1.0) is presented by the optotype presenting optical system 30.

Next, the examiner operates the switch unit 6b to input a signal to alternate between providing and not providing a prism amount. Based on this input signal, the control unit 70 drives the deflection mirror 81 so that the state of providing the prism amount changes.

The subject is asked to check whether the appearance of the optotype changes with and without the addition of prism. For example, when prism amount is added, the subject looks at the optotype with their eyes converged when prism amount is not added, which results in poorer appearance of the optotype and a sense of insufficient correction power. In this case, check whether there is a difference in appearance between when the correction power is increased by one step without prism amount added and when the correction power is left unchanged with prism amount added. If there is no difference in appearance, it can be confirmed that adding prism amount to the subject puts less strain on the eyes and allows more appropriate correction with a weaker correction power.

<Prescribing corrective lenses through subjective testing>
If the above-mentioned confirmation test of the appearance can be performed, the subjective test for prescribing the corrective lens can be performed based on the confirmation test. Since the optometry device of this embodiment is equipped with the subjective measurement optical system 25, the subjective test can be performed directly. For example, the examiner displays the measurement result of the eye refractive power corresponding to the change in the prism amount on the monitor 6a, and selects the prism amount and the objectively measured eye refractive power that are considered to be suitable for the prescription of the eye to be examined by the controller 6. Based on this selection signal, the control unit 70 determines the initial value of the prism amount and the correction power in the subjective measurement, and drives the deflection mirror 81 and the correction optical system 60 so that the selected prism amount and correction power are obtained. This allows the subjective measurement to be performed smoothly. Then, the final prescription power of the corrective lens can be determined by the subjective test. Since the subjective test for prescribing the corrective lens is well known, a detailed description will be omitted.

REFERENCE SIGNS LIST 1 optometry device 6 controller 6a monitor 7 measurement unit 10 objective measurement optical system 30 optotype presenting optical system 50 observation optical system 52 imaging element 70 control unit 81 deflection mirror

Claims (6)

An optometry apparatus for testing a visual function of a subject's eye,
an optotype presenting means having a pair of optotype presenting means for a right eye and an optotype presenting means for a left eye for presenting optotypes to the left and right eyes to be examined;
An eye refractive power measuring means for objectively measuring the eye refractive power of the subject's eye;
a prism amount changing means for changing an amount of prism to be applied to at least one of the left and right eyes to be examined;
An output control means,
The output control means presents an optotype to the test eye using the optotype presenting means, changes the prism amount applied to the test eye to at least two different states using the prism amount changing means, acquires the ocular refractive power of the test eye in each state in which the prism amount is changed using the ocular refractive power measuring means , and outputs the acquired ocular refractive power in correspondence with each prism amount applied to the test eye. The optometric apparatus according to claim 1,
an eye characteristic acquiring means for acquiring characteristic information of the subject's eye in each state of change in the amount of prism applied to the subject's eye when the eye refractive power is measured by the eye refractive power measuring means;
The eye examination apparatus according to claim 1, wherein the output control means outputs the characteristic information acquired by the eye characteristic acquisition means in correspondence with each prism amount applied to the subject's eye. The optometric apparatus according to claim 2,
an eye refractive power change acquiring means for acquiring a change in eye refractive power of the subject's eye over time by the eye refractive power measuring means;
the eye characteristic acquisition means is means for acquiring characteristic information of the change in eye refractive power over time based on the change in eye refractive power acquired by the eye refractive power change acquisition means;
The output control means outputs characteristic information on the change over time in eye refractive power acquired by the eye characteristic acquisition means in correspondence with each prism amount applied to the subject's eye. In the optometric apparatus according to claim 2 or 3,
an anterior segment imaging means for imaging an anterior segment of a subject's eye;
the eye characteristic acquisition means includes a minute displacement acquisition means for acquiring information on minute displacement of eye movement of the subject's eye over time based on an anterior eye image captured by the anterior eye imaging means,
The optometry apparatus, wherein the output control means outputs information on the minute displacement acquired by the minute displacement acquisition means in correspondence with each prism amount imparted to the subject's eye. The optometric apparatus according to claim 1,
The output control means controls the prism amount changing means to continuously change the amount of prism applied to the test eye while continuously executing measurements by the eye refractive power measuring means, thereby continuously obtaining the eye refractive power corresponding to the amount of prism applied to the test eye. A control program for an optometry apparatus, which is used in an optometry apparatus including a pair of optotype presenting means for a right eye and an optotype presenting means for a left eye for presenting optotypes to the left and right eyes to be examined, an ocular refractive power measuring means for objectively measuring the ocular refractive power of the eye to be examined, and a prism amount changing means for changing a prism amount to be applied to at least one of the left and right eyes to be examined,
a target presenting step of presenting a target to the subject's eye by the target presenting means;
an ocular refractive power acquisition step of changing the prism amount applied to the subject's eye to at least two different states by the prism amount changing means and acquiring the ocular refractive power of the subject's eye in each state in which the prism amount is changed by the ocular refractive power measuring means;
and an output step of outputting the acquired eye refractive power in correspondence with each prism amount imparted to the subject's eye.