Strabismus examination filters, strabismus examination filter sets, and strabismus examination instruments

Abstract

To provide a filter, filter set, or apparatus for strabismus examination that enables a more visually understandable examination. [Solution] A transmission-type Fourier transform hologram filter that projects a virtual image by transmitting light from a light source in a straight line, and is brought close to the eye of a subject to cover their field of view, and is used as a filter for strabismus testing to determine the presence or degree of strabismus symptoms based on how the subject perceives the virtual image.

Description

Technical Field

[0001] The present invention relates to a filter for perspective inspection, a filter set for perspective inspection, and an instrument for perspective inspection.

Background Art

[0002] Perspective not only causes cosmetic problems, but depending on the degree, symptoms such as "diplopia" where the object being looked at appears to be two, and the "suppression" symptom described later may occur, which may also cause problems in daily life. Therefore, a method for improving the perspective symptom is desired.

[0003] As shown in the upper diagram of FIG. 1, when there is no perspective symptom, the light passing through the pupil is projected onto the center of both the right eye and the left eye, and the information is appropriately processed in the brain and the target object is recognized as one.

[0004] On the other hand, when there is a perspective symptom, as shown in the lower diagram of FIG. 1, the light is projected onto the center of one eye, but the light is projected outside the center of the other eye. As a result, the symptom of "diplopia" where the target object appears double occurs.

[0005] In addition, when the symptom of diplopia appears, it causes inconvenience in life, so the symptom of "suppression" may occur where the eye with the deviated line of sight stops recognizing the image. When suppression develops, the patient can no longer be aware that their own eye has deviated. If they are aware, they may be able to correct the deviation themselves by measures such as "squinting", but if they are not aware, they will not be able to take such measures. In this case, the eye with the perspective symptom remains deviated, causing a cosmetic problem.

[0006] Basically, surgical operations are adopted to improve such perspective symptoms. However, just performing a surgical operation will gradually cause the perspective symptom to return. To prevent this, it is necessary to carry out vision training for perspective in combination with the surgical operation.

[0007] When implementing vision training to prevent the recurrence of strabismus, it is necessary to assess each patient's condition to set a vision training plan, and at this time, the degree of strabismus is examined.

[0008] Thus, examining the degree of strabismus symptoms remains necessary for patients not only before surgery but also after surgery. While strabismus symptoms are generally assessed by observing how light from a light source is perceived, in the case of young children, their understanding of left and right concepts is often insufficient, and a more intuitive and easy-to-understand examination method is needed. [Overview of the project] [Problems that the invention aims to solve]

[0009] In view of the circumstances described above, the object of the present invention is to provide a filter for strabismus examination, a filter set for strabismus examination, or a strabismus examination device that enables a more visually understandable examination. [Means for solving the problem]

[0010] The inventors diligently conducted research to solve the above problems and found that by using a transmission Fourier transform hologram filter, inspections can be performed in a more visually understandable way. Based on this finding, the inventors conducted further research and completed the present invention.

[0011] In other words, the present invention provides the following strabismus testing filters, strabismus testing filter sets, and strabismus testing instruments. Section 1. A transmission-type Fourier transform hologram filter that projects a virtual image by allowing light from a light source to pass straight through, A filter for strabismus testing, which is placed close to the subject's eye to cover their field of vision, and used to determine the presence or degree of strabismus symptoms based on how the subject perceives the virtual image. Section 2. A filter as described in item 1, which is placed close to one of the subject's eyes to cover their field of vision. Section 3. The filter described in item 1, which is used by covering one side of a strabismus examination device through which light from the light source is transmitted. Section 4. A filter set for strabismus testing, consisting of multiple filters as described in item 3. Section 5. The strabismus testing apparatus is at least one selected from the group consisting of a prism bar, a prism, and a strabismus testing lens, as described in item 3 or the filter set described in item 4. Section 6. The strabismus testing apparatus is a prism bar, and the filter described in item 3 or the filter set described in item 4 is used to cover one side of some or all of the prism units constituting the prism bar through which light from the light source passes. Item 7. A strabismus testing instrument covered with at least one filter described in item 3. Section 8. A filter set for strabismus testing, as described in item 2, comprising multiple filters in which the size of the virtual image projected by light transmitted straight through from a light source is progressively different. Section 9. A filter set for strabismus testing, consisting of the filters described in item 1, which are placed close to both eyes of the subject to cover their field of vision. Section 10. The filter set according to item 9, wherein each filter portion, positioned close to the left and right eyes of the subject and covering the field of view, projects different virtual images when light from the light source is transmitted straight through, and these portions may be connected to each other or configured separately. Section 11. A strabismus examination method comprising the step of bringing a transmissive hologram filter, which projects a virtual image by allowing light from a light source to pass straight through, close to the subject's eye to cover the field of view, and determining the presence or degree of strabismus symptoms based on how the subject perceives the virtual image. [Effects of the Invention]

[0012] According to the filter for strabismus examination, the filter set for strabismus examination, or the instrument for strabismus examination of the present invention, an examination can be carried out in a more visually understandable form.

Brief Description of Drawings

[0013] [Figure 1] Explanatory drawing of diplopia symptoms by strabismus. [Figure 2] Explanatory drawing of an example of the usage method of the filter for strabismus examination of the present invention. [Figure 3] Explanatory drawing of an example of the usage method of the filter for strabismus examination of the present invention. [Figure 4] Explanatory drawing of an example of the usage method of the filter set for strabismus examination of the present invention. [Figure 5] Explanatory drawing of an example of the usage method of the filter set for strabismus examination and the instrument for strabismus examination of the present invention. [Figure 6] Explanatory drawing of an example of the usage method of the filter set for strabismus examination and the instrument for strabismus examination of the present invention.

Modes for Carrying Out the Invention

[0014] In this specification, "containing" is a concept encompassing any of "comprise", "consist essentially of", and "consist of". Also, in this specification, when a numerical range is indicated as "A to B", it means A or more and B or less.

[0015] The filter for strabismus examination of the present invention is a transmissive Fourier transform hologram filter that allows light from a light source to pass straight through and projects a virtual image. The filter is brought close to the subject's eye to cover the visual field, and the presence or degree of strabismus symptoms is determined by how the virtual image is seen through the filter.

[0016] The light source is not particularly limited as long as it is a light source that emits visible light. For example, an LED light source or the like can be preferably used, but of course it is not limited thereto.

[0017] The hologram filter used is a transmission-type Fourier transform hologram filter that diffracts light incident from a light source and reconstructs a virtual image at a distance. Furthermore, the hologram filter used projects the virtual image onto the light that has passed through it.

[0018] There are no particular limitations on the shape of the virtual image, and it can be set as appropriate. For example, the projected virtual image could be an animal, a star, a vehicle such as a car or airplane, etc., and there are no particular limitations. Figure 2 shows an example where the shape of a pentagram is projected.

[0019] There are no particular limitations on the size of the hologram filter, as long as it is large enough to adequately cover one eye. For example, a size of 18mm x 22mm to 40mm x 40mm in length and width is preferable. There are also no particular limitations on the thickness of the filter, but for example, a thickness of 20 to 2000 μm is preferable.

[0020] Such a hologram filter can be manufactured, for example, by creating fine irregularities on one surface of a transparent filter using electron beam lithography or the like.

[0021] There are no particular restrictions on the material of the hologram filter; for example, resins such as acrylic, polycarbonate (PC), polyvinyl chloride (PVC), polyethylene terephthalate (PET), and biaxially oriented polypropylene (OPP) can be used individually or in blends of several types. [Examples]

[0022] The embodiments of the present invention will be described in more detail below based on examples, but the present invention is not limited to these.

[0023] When performing a strabismus examination, it is preferable to cover one eye (preferably the eye suspected of having strabismus symptoms) with the filter, as shown in Figure 2. As shown in Figure 2, when the eye with strabismus symptoms is covered with the filter and light from a light source enters the eye with strabismus symptoms, the light will not enter the appropriate position on the retina of the eye.

[0024] If an eye with strabismus symptoms is covered with the hologram filter described above, and that eye has strabismus symptoms but does not exhibit suppression symptoms, the virtual image seen through the hologram filter and the light source seen without the hologram filter will appear separately without completely overlapping (diplopia).

[0025] On the other hand, in patients experiencing suppression symptoms, if the eye with strabismus is covered with the aforementioned hologram filter, the virtual image that would normally be visible through the hologram filter is not recognized due to the suppression symptoms. Instead, only the light that directly enters the other eye, which does not have strabismus, from the light source is recognized.

[0026] For example, in the embodiment shown in Figure 2, if the left eye exhibits symptoms of exotropia, the right eye can perceive the light source in the center of the field of view. In addition, the left eye perceives a virtual image transmitted through the hologram filter to the right of the real image of the light source perceived by the right eye. In this case, if there is a suppression symptom in the left eye, the virtual image will not be perceived, and only the real image of the light source, without the hologram filter, will be perceived by the right eye.

[0027] By employing this testing method, subjects can more easily determine whether the virtual image seen through the hologram filter is seen on the left or right eye, in comparison to the target (the real image of the light source without the hologram filter). In particular, when the subject is young, or when the eye affected by strabismus (sometimes frequently) switches sides, it can be difficult to convey the information perceived through the strabismus symptoms. The strabismus testing filter of the present invention can assist in responding in such cases.

[0028] Furthermore, the strabismus inspection filter of the present invention can be suitably used in the examination of even minor strabismus symptoms, as shown in Figure 3. Figure 3 shows a case in which the left eye has minor strabismus symptoms. Even when such symptoms are minor, the shape of the image perceived by the eye with strabismus symptoms (the left eye in Figure 3) differs from the shape of the image perceived by the eye without strabismus symptoms, making it easy to understand the state of the strabismus symptoms. Needless to say, it is also easy to understand suppression symptoms in this case as well.

[0029] In this specification, slight strabismus is defined as a condition in which the visual axis is deviated within 5.7° from the center to which it should naturally be pointed.

[0030] The strabismus inspection filter of the present invention can also be used by being provided to cover one side of a strabismus inspection device, such as a strabismus inspection lens, that transmits light from a light source. For example, it is a suitable embodiment to use the strabismus inspection filter by attaching one side of it to the strabismus inspection device with an adhesive surface.

[0031] Up to this point, embodiments of the strabismus examination filter of the present invention have been shown in which the filter is used in close proximity to one eye of the subject. However, as shown in Figure 4, embodiments in which the filter is used in close proximity to both eyes of the subject are also preferable. In this case, as shown in Figure 4, it is preferable that the virtual images projected through the filters used for the left and right eyes are different. More preferably, by making one virtual image larger than the other and forming a larger cavity in its center than the other virtual image, more precise diagnosis becomes possible. Thus, it is also a preferred embodiment to use a combination of two strabismus examination filters (a strabismus examination filter set) for the left and right eyes, which can project different virtual images to each.

[0032] As shown in Figure 5, an embodiment is also preferred in which multiple strabismus testing filters are prepared for one eye, and the virtual images projected from these filters are of progressively different sizes.

[0033] For eyes exhibiting strabismus symptoms, the filter that projects the smallest virtual image from the above-mentioned strabismus test filter set is used first. If the virtual image cannot be recognized, it can be determined that suppression symptoms are present. Subsequently, the test is conducted by using filters that project progressively larger virtual images until the virtual image can be confirmed, thereby diagnosing the extent of the suppression symptoms.

[0034] Conversely, if the virtual image can be recognized by using the smallest projected image first, then filters projecting progressively larger virtual images can be used. If areas in the visual field where the virtual image cannot be recognized are identified, a diagnosis of suppression symptoms can be made in the peripheral visual field.

[0035] As shown in Figure 6, it is also preferable to use a strabismus inspection filter that covers one side of each prism unit (or one or some of the prism units) that makes up the prism bar used for strabismus inspection, through which light from the light source is transmitted. It is also preferable to provide an adhesive surface on one side of the strabismus inspection filter and attach it to one or more prisms.

[0036] (Double vision recognition rate evaluation test) As shown in Figure 2, when strabismus symptoms are present, a symptom of "diplopia" (seeing two objects) may appear, and in some cases, inhibitory symptoms may also appear. Eleven patients aged 4 years 8 months to 9 years 4 months undergoing inhibitory deactivation training were fitted with a transmissive Fourier transform hologram filter (product name: Fantaglass) that allows light from a light source to pass straight through and project a virtual image into one eye with strabismus symptoms. A Diplopia test (a test in which patients are asked whether they see one light or two, and if two, whether the second one is in the right or left eye, by covering one eye or leaving the covered eye open) was performed to assess how they perceived light from a light source. For comparison, the same test was also performed on the same 11 patients without the transmissive Fourier transform hologram filter.

[0037] (Results of the double vision recognition rate evaluation test) As shown in Figure 2, when a patient with strabismus symptoms but no suppression symptoms looks at a light source, the resulting image is perceived as two separate light sources. In this study, when a transmission Fourier transform hologram filter (product name: Fantaglass) was worn, 93.5% of patients perceived two images (i.e., they had diplopia symptoms, but suppression symptoms were suppressed). When the same patients were not worn with the transmission Fourier transform hologram filter (product name: Fantaglass), only 76.5% perceived two images. This result suggests that using a transmission Fourier transform hologram filter allows for a more accurate detection of the presence or absence of suppression symptoms.

[0038] Furthermore, among the 76.5% of patients who perceived two light sources without wearing the above-mentioned transmission-type Fourier transform hologram filter (product name: Fantaglass), 12.7% were found to have misperceived which of the two images they perceived on which side (left or right) by wearing the transmission-type Fourier transform hologram filter on one eye with strabismus symptoms, causing them to perceive the light source as a virtual image.

[0039] Although embodiments of the present invention have been described above, the present invention is not limited in any way to these examples, and can be implemented in various forms without departing from the spirit of the invention.

Claims

1. A transmission-type Fourier transform hologram filter that projects a virtual image by allowing light from a light source to pass straight through, A filter for strabismus testing, which is placed close to the subject's eye to cover their field of vision, and used to determine the presence or degree of strabismus symptoms based on how the subject perceives the virtual image.

2. The filter according to claim 1, which is positioned close to one of the subject's eyes to cover their field of vision.

3. The filter according to claim 1, which is used by covering one side of a strabismus examination device through which light from the light source is transmitted.

4. A filter set for strabismus examination comprising multiple filters according to claim 3.

5. The filter according to claim 3 or the filter set according to claim 4, wherein the strabismus testing instrument is at least one selected from the group consisting of a prism bar, a prism, and a strabismus testing lens.

6. The strabismus testing instrument is a prism bar, and the filter according to claim 3 or the filter set according to claim 4 is used by covering one side of some or all of the prism units in the plurality of prism units constituting the prism bar through which light from the light source is transmitted.

7. A strabismus testing instrument covered with at least one filter according to claim 3.

8. A filter set for inspecting strabismus, according to claim 2, comprising a plurality of filters in which the size of the virtual image projected by light transmitted straight through from a light source is steppedly different.

9. A filter set for strabismus examination comprising the filter described in claim 1, which is brought close to both eyes of the subject to cover their field of vision.

10. The filter set according to claim 9, wherein each filter portion, positioned close to the left and right eyes of the subject and covering the field of view, projects different virtual images when light from the light source is transmitted straight through, and these portions may be connected to each other or configured separately.

Images