CN215900286U - Visual function training instrument - Google Patents

Abstract

The utility model provides a visual function training appearance, its characterized in that, this visual function training appearance separately sets up with aberration measurement system to and, this visual function training appearance includes: a refractive correction device, comprising: a refractive correction optical mechanism, a refractive correction manual adjustment mechanism, a refractive correction lock mechanism; and the visual function training device comprises a visual target device and a transponder device. The portable correction training instrument provided by the disclosure can be combined with an accurate measurement system for application, the measurement and treatment quality is guaranteed, the application cost is effectively reduced, the application scene of the technology disclosed by the disclosure is expanded more widely, and a more practical commercial application mode and application prospects can be provided.

Description

Visual function training instrument

Technical Field

The present disclosure relates to eye vision optical applications, and more particularly, to a visual function training instrument that can be provided as a head-mounted device in a portable manner.

Background

Discussion of the related Art

Refractive error is a global public health problem. 2017, the research report of the world health organization shows that the number of Chinese myopia patients is as many as 6 hundred million, the myopia rate of the teenagers in China is high and is in the first place in the world, and the myopia rate also sharply increases at a rate of 20% per year. For the vision function decline of teenagers, the simple ametropia patient can obtain good corrected vision by testing and matching correct correction glasses, and meanwhile, the poor eye using habit is corrected to control the further development of ametropia; however, in the case of visual function deterioration caused by non-ametropic eye diseases, and in the case of ametropia corrected eyes, good subjective visual function cannot be obtained, further examination is required to confirm the cause of the disease, and targeted training and recovery of monocular/binocular vision functions are required.

The human eye, as a typical optical system, contains various aberration components including more higher-order aberrations such as coma, trefoil, spherical aberration, etc., in addition to defocus and astigmatism. The Hartmann wavefront sensing technique is the most commonly used technique in the measurement of higher order aberrations in the human eye. US6575572B2, US6439720B1, US7419264B1, chinese patents CN101803906, CN106163378A, 201010121408.6, etc. report the application of various hartmann wavefront techniques in the measurement of aberrations of the human eye.

Before visual training, the aberration of human eyes needs to be effectively corrected, and a stimulation target can generate a clear enough image on the retinas of the human eyes in the training process so as to improve the training efficiency to the maximum extent.

In the utility model patent CN101947157A, adaptive optics technology is used to measure and correct low-order and high-order aberrations of human eyes, and provide clear visual stimulation to human eyes, but the instrument cost is high, the structure is complex, and the portable application cannot be realized, so that the universal popularization is difficult.

The utility model patent publication No. CN101947157B proposes an instrument and a method for combining the adaptive optical aberration correction technology with visual perception learning training, and corrects all dynamic aberrations of human eyes in real time through the adaptive optical technology to obtain fine retina stimulation close to the diffraction limit. This approach is optimal from the technical point of view, but since the adaptive optics technology requires the use of special devices such as wavefront sensors, wavefront correctors, corrective controllers, etc., and particularly the wavefront correctors are used in combination with the corrective controllers, the complex variable optical surfaces and the precise mechanical control are adopted, and high-voltage amplification units are often included, so that the equipment is expensive. On the other hand, the instrument is bulky due to the matching of the human eye with the wavefront correction device. These factors are not favorable for clinical application and wide popularization of the patent technical scheme. The contents of the cited publications are all incorporated by reference into the present disclosure. However, myopia in teenagers in China is the most common cause of high-incidence hypopsia for many years, and the above cited patents and similar technical schemes are difficult to meet the common demand.

The chinese invention patent CN103784298A proposes a head-wearing vision training apparatus for correcting human eye aberration, which adopts a special structure to correct the low-order aberration and the high-order aberration of the human eye, and the correction purpose of the high-order aberration needs to be individually set in the correction design. The patent proposes to provide correction settings for one state in advance. By "personalized" is meant that the human eye aberrations are different for different patients and that even for the same patient, the human eye parallax of the individual will change at different times and in different situations, such as after running versus resting, and in different moods. Therefore, although the price of a single personalized device is acceptable, the patent solution provides a fixed aberration correction device, such as a correction glasses, but it is impossible to provide various fixed aberration correction devices that can cope with the human eye's aberration's dynamic variability, thereby further increasing the difficulty of use, and thus it is difficult to have practical value and ideal effect in practical application.

The contents of the cited publications are all incorporated by reference into the present disclosure.

SUMMERY OF THE UTILITY MODEL

[ problem to be solved ]

Considering the difficult task of myopia prevention and control in the future of China, a portable visual function measuring and training device or system which is suitable for various use scenes and has acceptable price is needed in the field to meet the requirement.

The utility model aims to improve the cost performance of the equipment by reasonably arranging the equipment components.

The inventors have noted that high performance visual perception learning trainers, often incorporating high performance aberration measurement systems, include measuring high and low order aberrations of the human eye. Measurement of higher order aberrations, typically using Hartmann wavefront sensing techniques, is the most common technique used in the measurement of higher order aberrations in the human eye. However, the precision of high-order measurement devices is a major factor in the cost of the equipment.

Therefore, as in the above-cited chinese patent CN103784298A, the vision training device omits a vision measuring system, and directly configures a personalized vision correction device, i.e. a correction glasses, but the correction glasses are fixed correction devices. The vision correction of the testee needs to be accurately adjusted at any time or many times in the vision training process, and the requirement is difficult to meet.

[ solution ]

In order to solve one of the above technical problems, the present disclosure provides the following technical solutions:

in a first aspect of the present disclosure, a visual function training instrument is provided, wherein the visual function training instrument is separately provided from an aberration measuring system, and the visual function training instrument includes: a refractive correction device, comprising: a refractive correction optical mechanism, a refractive correction manual adjustment mechanism, a refractive correction lock mechanism; and the visual function training device comprises a visual target device and a transponder device.

In at least one embodiment of the present disclosure, the visual function training instrument is a monocular visual function training instrument or a binocular visual function training instrument, and each optical path includes: the focusing mechanism compensates the defocusing of the human eyes of the tested person; the astigmatism compensation mechanism compensates astigmatism of human eyes of the person to be measured; and the visual target device comprises a visual target imaging objective lens and a visual target display device, and the visual target imaging objective lens images the image on the visual target display device on the retina of the human eye of the person to be detected.

According to at least one embodiment of the present disclosure, wherein it is a binocular function training instrument, wherein the binocular optical path settings are the same.

According to at least one embodiment of the present disclosure, the focus mechanism includes a relatively movable focus lens group or a liquid lens.

According to at least one embodiment of the present disclosure, the astigmatism compensation mechanism includes a group of relatively rotatable cylindrical lenses.

According to at least one embodiment of the present disclosure, the control system controls the target device to provide a target display image based on a built-in program and subject response information.

According to at least one embodiment of the present disclosure, the focusing lens group is selected from a spherical lens and an aspherical lens having the same or different optical power values.

According to at least one embodiment of the present disclosure, the focusing lens group is selected from a positive cylindrical lens/positive cylindrical lens, a positive cylindrical lens/negative cylindrical lens, a negative cylindrical lens/negative cylindrical lens, and a combination thereof.

According to at least one embodiment of the present disclosure, the visual target display device is selected from a liquid crystal display, a plasma display, an electroluminescence display, and an organic light emitting display.

According to at least one embodiment of the present disclosure, the method further comprises: the instrument shell and the head connecting and fixing device of the tested person are connected with the instrument shell and fixed on the head of the tested person in a use state.

According to at least one embodiment of the present disclosure, the examinee can independently hold the binocular visual function training instrument by himself/herself via the examinee's head attachment fixing device.

According to at least one embodiment of the present disclosure, the subject's head fixation device includes an adjustable strap.

According to at least one embodiment of this disclosure, wherein still include interpupillary distance manual regulation mechanism among the visual function training appearance, it includes left way interpupillary distance adjust knob and right way interpupillary distance adjust knob to contain locking mechanism.

[ beneficial effects of the utility model ]

There are a variety of visual function training instruments known in the art, and it has also been considered to provide a visual function training instrument with reduced cost. But the general option is to sacrifice the performance of some aspect of the visual function training apparatus in the hope of obtaining a compromise solution. For example, to reduce cost, it may be desirable to choose to sacrifice the aberration measurement function.

Compared with the prior art, the technical scheme provided by the disclosure has the advantages that the visual function training instruments and the aberration measuring system are separately arranged, the multiple visual function training instruments share one high-performance aberration measuring system, the possibility is provided for adopting the high-performance aberration measuring device or system, the acceptable cost is provided at the same time, and the opportunity of receiving vision correction is provided for more people.

In the present disclosure, the aberration measurement system used in association with the visual function training apparatus may employ a hartmann aberration measurement technique to ensure the accuracy of the high-order aberration measurement.

The portable correction training instrument provided by the disclosure can be combined with an accurate measurement system for application, the measurement and treatment quality is guaranteed, the application cost is effectively reduced, the application scene of the technology disclosed by the disclosure is expanded more widely, and a more practical commercial application mode and application prospects can be provided.

Drawings

The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the disclosure and together with the description serve to explain the principles of the disclosure. The structure, objects and features of the present invention will be more readily understood by those skilled in the art after a reading of the embodiments of the present invention with reference to the accompanying drawings, in which:

fig. 1 is a binocular disparity measuring apparatus which is provided separately from the visual function training instrument of the present invention, provided separately, and can be used in association with the present invention, and fig. 1 shows the main components of the binocular disparity measuring system;

FIG. 2 is a block diagram showing the operation of a control system of the visual function training apparatus according to embodiment 1 of the present invention;

FIG. 3 is a schematic view showing the optical path arrangement of a visual function training instrument according to embodiment 1 of the present invention;

FIG. 4 illustrates a head-mounted embodiment of a vision correction apparatus of the present invention shown in FIG. 2; and

fig. 5 is a block diagram schematic of the arrangement of the control system of the present disclosure.

Description of the reference numerals

1 human eye

1a human eye (left eye)

1b human eye (Right eye)

2 infrared light emitting diode

3 first pupil Camera

4 second pupil Camera

5 first aberration compensating lens

6 second aberration compensating lens

7 rotating cylindrical lens pair

8 first spectroscope

10 collimating lens

11 Beacon light source

12 second beam splitter

13 sighting mark imaging objective lens

14 reflecting mirror

16-aperture dividing element

17 computer

20 photo detector

21 first optotype display device

31 first focusing lens

32 second focusing lens

33 first cylindrical lens

34 second cylindrical lens

36 second sighting mark display device

100 wave front aberration measuring device

110 outer casing

120 operation prompt screen

130 control system

140 left eye system

141 left eye translation knob

150 eyes system

151 right eye translation knob

170 transponder

Detailed Description

Embodiments and examples of the present disclosure are described below with reference to the drawings. It is emphasized that this description is merely exemplary in nature and is not intended to limit the scope or application of the present disclosure. Moreover, descriptions of some well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concepts of the present disclosure.

Like reference numerals are used throughout the figures to describe like or similar parts. The various features disclosed herein can be used alone, or in varying combinations with each other and are not intended to limit the utility model to the particular combinations described herein. Accordingly, the described embodiments are not intended to limit the scope of the claims.

The description may employ the phrases "in an embodiment," "in some embodiments," or "in other embodiments," which may each refer to one or more of the same or different embodiments, respectively, in accordance with the disclosure herein.

[ example 1]

Example 1 the application of the present invention is illustrated in conjunction with a test and training procedure for a subject, and shows a preferred embodiment of the apparatus provided by the present invention.

1 aberration measurement and aberration measurement device

In a typical embodiment, the aberration measurement is first performed on the subject. Embodiment 1 the measurement is performed by using a wavefront aberration measuring apparatus 100, which is typically provided in a professional institution such as a hospital or other ophthalmic treatment institution.

Fig. 1 shows the main components of the wavefront aberration measuring apparatus 100.

The infrared light emitting diode 2 is used for illuminating the pupil of a human eye 1 (left eye) of a measured person, the computer 17 obtains the coordinate of the pupil center point according to the images collected by the first pupil camera 3 and the second pupil camera 4, the up-down, left-right and front-back displacement of the system is calculated through decomposition, and the computer 17 controls the left path component of the system to move integrally, so that the pupil center of the measured human eye 1 is finally positioned at the optical axis entrance pupil of the system.

The right eye makes the pupil center of the eye to be measured finally located at the entrance pupil of the optical axis of the system by the same working principle. After the pupil three-dimensional positioning is finished, binocular pupil distance parameters can be obtained according to the movement amount of the left path and the right path of the system relative to the original position in the positioning process. The same fixation target is displayed in the dual-purpose optotype display device 21, as shown in fig. 1, the left eye (left eye 1) of the measured person observes the fixation target in the optotype display device 21 through the aberration compensation lens group (the first aberration compensation lens 5 and the second aberration compensation lens 6), the rotating cylindrical lens pair 7, the first spectroscope 8, the second spectroscope 12, the optotype imaging objective 13 and the reflector 14 for facilitating eyeball stabilization. The beacon light source 11 is collimated into parallel light by the collimating lens 10, then reflected by the reflector 9, then passes through the first spectroscope 8, passes through the rotating cylindrical lens pair 7 and the compensation lens groups 5 and 6, and enters the human eye 1 to be measured, the backward reflected light of the eyeground passes through the aberration compensation lens group (the first aberration compensation lens 5 and the second aberration compensation lens 6), the rotating cylindrical lens pair 7, the first spectroscope 8 and the second spectroscope 12, and then enters the light beam matching device 15 (aperture matching system), and the emergent light passes through the aperture dividing element 16 and enters the photoelectric detector 20. The measurement information obtained based on the wavefront detection technology is input into a computer, the defocus and astigmatism compensation amount is calculated based on a built-in program, the computer outputs a command to indicate an action mechanism (a servo motor or a hydraulic actuating device), the integral movement of the component combination in the dashed frame is controlled, the defocus compensation is completed, and the rotating cylindrical lens pair 7 is controlled to rotate by corresponding angles respectively to complete the astigmatism compensation. The right eye system implements aberration compensation with the same working principle. After the aberration compensation is completed, the photodetectors 20 in the wavefront aberration measurement subsystems of the left path and the right path in the system are simultaneously started. The method is used for objective measurement of wavefront aberration of the human eye.

The measured wavefront is divided into a plurality of sub-apertures by the aperture dividing element 16 and focused on the photoelectric detector 20, the computer 17 calculates the gravity center position of a focused light spot by processing a video signal, the near-field phase distribution of the measured wavefront can be restored by a wavefront reconstruction algorithm, including a phase diagram, a wavefront error, each order Zernike coefficient and the like, and by combining the defocusing and astigmatism values compensated by the aberration compensation subsystem, the ametropia information of the two measured eyes, including the defocusing, astigmatism and astigmatism axes of the left and right eyes, can be finally obtained.

2 visual function training instrument

Fig. 2 to 5 are schematic diagrams showing the structure, arrangement and use of a visual function training instrument 200 according to a preferred embodiment of the present disclosure, which is a head-mounted binocular visual function training instrument.

The visual function training instrument 200 includes the following configuration: a left eye system 140, a right eye system 150, a left eye translation knob 141 and a right eye translation knob 151 which are symmetrically arranged, and further comprises an operation prompt screen 120, a control system 130 and an instrument shell 110. In this embodiment, the operation prompt screen 120 is mounted on the instrument housing 110. As shown in fig. 4, the instrument case 110 is further provided with a head fixing device 160, and the portable binocular visual function training instrument of the present disclosure is further provided with a transponder 170 for learning training in a line type or a remote control type.

As described above, after obtaining the ametropia information of the left and right eyes of the examinee by the wavefront aberration measuring apparatus 100, the visual function training machine of the present disclosure can be used to perform the subsequent aberration correction and visual learning training of the eyes.

1) Preparation before use

As shown in fig. 4, the functional training apparatus 200 is first fitted to the head of the subject and is then stably attached. The head fixation device 160 may be arranged in a number of ways, not shown in detail, for example by providing the housing 110 with adjustable fixation means to meet the needs of persons with different head diameters. Such adjustable fixation devices, such as adjustable straps, having a plurality of grommets for use with fixation hooks, or a tensioning knob in combination with a threaded bolt shaft, or a tensioning strap, a tether tensioning arrangement, a velcro type arrangement, etc., provide stable adjustment to ensure primary positioning of the two eyes. In the using process, the training instrument is fixed on the head of a tested person and is independently supported by the head, so that the training instrument is easy to position and convenient to carry. Thus, the application scenario is more flexible.

As shown in fig. 2, typically, the practitioner inputs the ametropia information of the left eye 1a and the right eye 1b acquired by the aberration measuring device separately provided as described above into the operation prompt screen 120 of the visual interface of the control system 130, and the control system 130 can rapidly calculate the defocus and astigmatism values of the eye to be measured by using a preset program, and analyze the overall movement amount of the components in the dashed frame (the dashed frame indicates the device component set) and the rotation angle of the cylindrical lens as shown in fig. 3. Typically, as shown in fig. 3, the relative movement amount of the first focus lens 31 and the second focus lens 32 is calculated, and then the adjustment amount is moved as a whole within the dashed line frame, and the respective rotation amounts of the first cylindrical lens 33 and the second cylindrical lens 34 are calculated, and the operator performs manual adjustment by the operator using a mechanical adjustment mechanism according to the scribe line provided on the housing 110 of the present apparatus, thereby correcting the aberration, and then locks the locking mechanism.

2) Visual function measurement and training

After the aberration correction is completed, as shown in fig. 3, the control system 130 controls the second visual target display device 36 to generate a corresponding visual target, and performs a visual function measurement and training process on the subject. Usually, the testee interacts with the instrument through a voice interaction device or a button, in this embodiment, the responder 170 is provided to perform human-computer interaction to complete the visual function test and training task, and finally, the control system 130 may output the measurement and training result.

3) Binocular measurement and training

The right eye measurement and training is the same as the left eye operation. The left eye optical configuration and the right eye optical configuration are symmetrically disposed, and thus detailed description is omitted. Further, in the embodiment, after the left eye and right eye aberration correction is respectively completed, binocular alignment can be achieved through the simultaneous eye translation knob (the left eye translation knob 141, the right eye translation knob 151), and then binocular function measurement and training including binocular simultaneous vision, binocular fusion, stereoscopic vision, and the like are performed.

In this embodiment, a portable head-mounted vision function training device is provided, in which the components are fixed to the device body as much as possible, and in particular, the head-mounted vision function training device of embodiment 1 can be independently supported and maintained by the head, and the device can be adjusted manually by using a conventional simple mechanical adjustment structure to adjust the binocular positioning and to correct and adjust the vision by manual operation, thereby omitting automatic adjustment mechanisms such as a servo motor.

The head-mounted visual function training instrument according to embodiment 1 provides integration of aberration correction and visual function training, and additionally, can provide training for binocular fusion.

[ alternative embodiment ]

Many variations of the embodiments of the disclosure are possible. For example, the visual function training apparatus of the present disclosure may be set up for different aberration measuring devices, from a cost standpoint, or from an application of a newer technique. Because the required accessory figure of this disclosed visual function training appearance greatly reduces, its change sets up more easily. Therefore, the technical scheme disclosed by the utility model has better adaptability.

In other embodiments of this disclosure, still include pupil distance manual regulation mechanism (not shown in the figure), it includes left way pupil distance adjust knob and right way pupil distance adjust knob to contain locking mechanism.

According to the portable training instrument, the aberration measurement function and configuration are omitted in the training instrument, in addition, further optimization is further achieved, automatic aberration adjustment is omitted, manual aberration adjustment is changed, the number of accessories is greatly reduced, the equipment structure is simplified, and therefore the portable training instrument is easy to manufacture. In addition to being head-mounted, other ways are possible, such as being placed on a desktop for use with a compact architecture, and so forth.

Thus, the present disclosure also includes at least the following concepts:

concept 1. a visual function training instrument, characterized in that the visual function training instrument is provided separately from an aberration measuring system, and the visual function training instrument comprises:

a refractive correction device, comprising: a refractive correction optical mechanism, a refractive correction manual adjustment mechanism, a refractive correction lock mechanism; and

the visual function training device comprises a visual target device and a transponder device.

Concept 2. the visual function training instrument according to concept 1, wherein the visual function training instrument is a monocular visual function training instrument or a binocular visual function training instrument, and each optical path includes:

the focusing mechanism is used for compensating the defocusing of the human eyes of the tested person;

the astigmatism compensation mechanism is used for compensating astigmatism of human eyes of a measured person; and

the visual target device comprises a visual target imaging objective lens and a visual target display device, wherein the visual target imaging objective lens images an image on the visual target display device on the retina of the human eye of the person to be detected.

Concept 3. the visual function training instrument according to concept 2 is characterized in that it is a binocular visual function training instrument in which the setting of each eye path is the same.

Concept 4. the visual function training instrument according to concept 2 or 3, wherein the focusing mechanism includes a relatively movable focusing lens group or a liquid lens.

Concept 5. the visual function training instrument according to concept 2, wherein the astigmatism compensation mechanism includes a relatively rotatable cylindrical lens group.

Concept 6 the visual function training instrument according to concept 1, further comprising a control system that controls the visual target device to provide a visual target display image based on a built-in program and response information of the subject.

Concept 7. the visual function training instrument according to concept 2 or 4, wherein,

the focusing lens group is selected from spherical lenses and aspheric lenses with the same or different optical focal values.

Concept 8. the visual function training instrument according to concept 2 or 4, characterized in that: the focusing lens group is selected from positive cylindrical lens/positive cylindrical lens, positive cylindrical lens/negative cylindrical lens, negative cylindrical lens/negative cylindrical lens with the same or different optical focal values.

Concept 9. the visual function training instrument according to concept 2, wherein the visual target display device is selected from a liquid crystal display, a plasma display, an electroluminescent display, and an organic light emitting display.

Concept 10. the visual function training instrument according to concept 1, further comprising: the instrument shell and the head connecting and fixing device of the tested person are connected with the instrument shell and fixed on the head of the tested person in a use state.

Concept 11 the visual function training instrument according to concept 10, wherein the examinee himself or herself can independently hold the binocular visual function training instrument by attaching a fixing device to the examinee's head.

Concept 12. the visual function training apparatus according to concept 10 or 11, wherein the head fixing device of the subject includes an adjustable band.

Concept 13. the visual function training instrument according to concept 1, further comprising a manual interpupillary distance adjusting mechanism, which comprises a left-way interpupillary distance adjusting knob and a right-way interpupillary distance adjusting knob, and a locking mechanism.

It is to be understood that features of embodiments of the utility model may be combined in different configurations. It should be understood that embodiments of the present invention may include additional, fewer, or different components than those shown in the figures. It should be understood that the features of embodiments of the medical dressing of the present invention may be a combination of different configurations.

Although one embodiment of the present invention has been described in detail with reference to the drawings for purposes of illustration and description, it is to be understood that the disclosed treatment methods and apparatus are not to be construed as limiting the utility model. It will be readily apparent to those skilled in the art that various modifications to the foregoing embodiments may be made without departing from the scope of the utility model.

Claims (10)

1. A visual function training instrument, wherein the visual function training instrument is provided separately from an aberration measuring system, and wherein the visual function training instrument comprises:

a refractive correction device comprising: a refractive correction optical mechanism, a refractive correction manual adjustment mechanism, and a refractive correction lock mechanism; and

the visual function training device comprises a visual target device and a responder device.

2. A visual function training instrument according to claim 1, wherein the visual function training instrument is a monocular visual function training instrument or a binocular visual function training instrument, each visual path comprising:

the focusing mechanism is used for compensating defocusing of human eyes of a measured person;

the astigmatism compensation mechanism is used for compensating the astigmatism of human eyes of a measured person; and

the visual target device comprises a visual target imaging objective lens and a visual target display device, wherein the visual target imaging objective lens images the image on the visual target display device on the retina of the human eye of the tested person.

3. A visual function training instrument according to claim 2, wherein the visual function training instrument is a binocular visual function training instrument in which the eye path settings are the same.

4. A visual function training apparatus according to claim 2 or 3 wherein the focusing mechanism comprises a relatively movable focusing lens group or liquid lens.

5. A visual function training apparatus according to claim 2 or 3 wherein the astigmatism compensation mechanism comprises a set of relatively rotatable cylindrical lenses.

6. A visual function training instrument according to claim 1, further comprising a control system for controlling the visual target device to provide a visual target display image based on a built-in program and response information of the subject.

7. A visual function training instrument according to claim 1, further comprising:

an instrument housing, and

the fixing device is connected with the head of the tested person, is connected with the instrument shell and is fixed on the head of the tested person in a use state.

8. A visual function training instrument according to claim 2 or 3, wherein the visual function training instrument is independently held by the subject himself/herself via a head attachment fixture of the subject.

9. A visual function training instrument according to claim 8 wherein the securing means comprises an adjustable strap.

10. A visual function training instrument according to any one of claims 1 to 3, further comprising a manual interpupillary distance adjusting mechanism comprising a left interpupillary distance adjusting knob and a right interpupillary distance adjusting knob, and a locking mechanism.

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