JPH0315892B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a subjective ophthalmoscope that performs long-distance and short-distance tests of visual acuity, etc. (Prior Art) In general, tests using a subjective ophthalmoscope include a long-distance test and a short-distance test, and the near-distance test includes a presbyopia test, a short-distance visual acuity test, a squint test, and the like. For long-distance examinations, the distance is usually 5 m in front of the ophthalmoscope.
A visual chart such as an examination card or an eye chart is placed at the position of the patient, and the visual chart is made to be seen through the optometrist into the eye to be examined. Furthermore, in close-range examinations, a test card or a visual chart such as an eye chart is usually placed 25 to 40 cm in front of the optometrist, and this chart is shown through the optometrist to the eye to be examined. As a subjective ophthalmoscope that performs these tests,
For example, as shown in FIG.
As shown in the figure, see-through windows 3 and 3' are respectively provided on the walls 1a and 1a' of each lens housing 1 and 1' on the side of the eyes 2 and 2', and each of the lens housings 1 and 1' is Wall portions 1b, 1 on the viewing table (not shown) side
b' is provided with see-through windows 4, 4' corresponding to the see-through windows 3, 3', and each lens housing 1, 1'
A structure in which a spherical lens means 5 and a cylindrical lens means 6 and a spherical lens means 5' and a cylindrical lens means 6' are respectively disposed inside is known. Incidentally, the spherical lens means 5 includes two lens disks 5.
A, 5b, a plurality of spherical lenses 7 having different spherical powers are arranged at intervals in the circumferential direction on the peripheral edge of the lens disk 5a, and a plurality of spherical lenses 7 with different spherical powers are arranged on the peripheral edge of the lens disk 5b. Different spherical lenses 8 are arranged at intervals in the circumferential direction. Further, the cylindrical lens means 6 includes a plurality of cylindrical lenses 9 having different cylindrical powers arranged on the peripheral edge of a disk 10 at intervals in the circumferential direction. Moreover, the lens disc 5
By changing the combination of the spherical lenses 7 and 8 of a and 5b, the refractive power of the spherical lens means 5 can be variously changed, and by combining the spherical lens means 5 with the cylindrical lens 9 of the cylindrical lens means 6. , astigmatism, etc. can also be tested. The above-mentioned spherical lens means 5' and cylindrical lens means 6' are similarly constructed. In the figure, A is a measuring optical system consisting of a spherical lens means 5 and a cylindrical lens means 6, A' is a measuring optical system consisting of a spherical lens means 5' and a cylindrical lens means 6', 0,0' is a measuring optical system A, This is the optical axis of A′. When performing a long-distance examination using such a subjective ophthalmoscope, the lens housing 1,
1' without convergence, the optical axes of measurement optical systems A and A' are 0,
0' is made parallel. On the other hand, when performing close-range inspection, the lens housing 1,
1' is converged by θ so that the optical axes 0 and 0' of the measurement optical systems A and A' are directed toward the center of the viewing chart (not shown). (Problem to be solved by the invention) However, the convergence angle θ is the interpupillary distance between the eyes 2 and 2' to be examined.
Since it is constant regardless of the size of PD, if this interpupillary distance PD changes depending on the subject, the gaze distance C to the gaze point B changes. For example, if the standard interpupillary distance PD is 64 mm and the convergence angle is θ, and the fixation point distance C is 400 mm, then the interpupillary distance
When PD was different from the standard interpupillary distance, the gaze point distance C was as shown in the following table.

[Table] As the gaze distance C changes according to the interpupillary distance PD, conventionally it was necessary to change the position of the visual table according to the gaze distance C each time. When the position changes to PD ₁ and PD ₂ , it is necessary to change the gaze position from the position B to the positions B ₁ and B ₂ , which is inconvenient. Furthermore, since the lens housings 1, 1' accommodate measurement optical systems A, A' consisting of a large number of lens means, the lens housings 1, 1' are thick. For this reason, the lens housing 1,
There is also a problem in that there is a limit to the ability to approach the 1' with convergence, and in the case of a subject with a very short interpupillary distance PD, it may not be possible to perform a close-range examination. Therefore, this invention enables close-range inspection without congesting the lens housing.
The object of the present invention is to provide a subjective ophthalmoscope that can always converge at the same position regardless of the size of the interpupillary distance, and can perform close-range examination even in the case of a subject with a very small interpupillary distance. It is. (Means for Solving the Problems) In order to achieve this object, the present invention provides a subjective ophthalmoscope in which a pair of lens means for measuring refractive power is disposed on the left and right sides. A first prism means facing opposite to the center side between the lens means is disposed near the eye placement side of the lens means, and a second prism means whose base direction faces the center side between the lens means. The present invention is characterized in that the prism means is disposed near the viewing table side of the lens means. (Function) According to such a configuration, by appropriately selecting the refractive power of the first and second prism means according to the interpupillary distance of the subject, the optical axis of the subject's eye is aligned with the refraction of the first prism means. This action causes the optical axis to coincide with the optical axis of the measurement optical system, and this optical axis converges on a viewing table at a predetermined viewing distance due to the refraction action of the second prism means. (Example) Hereinafter, an example of the present invention will be described based on FIGS. 1 and 2. FIG. 1 shows an embodiment of the present invention. In FIG. 1, reference numerals 11 and 11' denote lens housings that are held in a frame (not shown) so as to be able to adjust relative approach and separation, and this lens housing 1
1 and 11' are adapted to be driven toward and away from each other by a pulse motor (not shown). Transparent windows 13, 13' are formed in the walls 11a, 11a' of the lens housings 11, 11' on the side of the eyes to be examined 12, 12'.
There are transparent windows 13, 13' on the walls 11b, 1b' on the fourth side.
Perspective windows 15, 15' corresponding to the two are formed. Measurement optical system 1 is installed inside the lens housing 1, 1'.
6, 16' are arranged. This measurement optical system 1
6 and 16' have the same configuration, so only the measurement optical system 16 will be explained, and the explanation of the measurement optical system 16' will be omitted by using the reference numeral of the measurement optical system 16 with a dash. This measurement optical system 16 includes a lens means 17 and a first,
First and second prisms 1 as second prism means
8 and 19, and the lens means 17 is composed of spherical lens means 20 and 21 and cylindrical lens means 22. The spherical lens means 20, 21 are formed by arranging a plurality of spherical lenses 20b, 21b having different spherical powers in the circumferential direction on the peripheral edge of a disk 20a, 21a, and the cylindrical lens means 22 is formed by arranging a plurality of spherical lenses 20b, 21b having different spherical powers on the peripheral edge of a disk 20a, 21a.
A plurality of cylindrical lenses 2 with different cylindrical powers are arranged around the periphery of the cylindrical lens 2.
2b arranged in the circumferential direction. The disks 20a, 21a of the spherical lens means 20, 21 and the disk 22a of the cylindrical lens means 22 are each rotated by a pulse motor (not shown). The above-mentioned first prism 18 is disposed between the lens means 17 and the transparent window 13, and the base 18a is located on the opposite side from the center between the lens housings 11 and 11', that is, between the lens means 17 and 17'. is facing away from the center. Second prism 19
is disposed between the lens means 17 and the transparent window 15, and the base 19a is located on the center side between the lens housings 11 and 11', that is, the lens means 17 and 1
It is directed towards the center between 7'. A plurality of first and second prisms 18 and 19 having different degrees of refraction are prepared, and one of them is inserted into the lens housing 11 in a detachable manner. Next, the operation of the subjective ophthalmoscope having such a configuration will be explained. Now, when changing from a long-distance examination to a near-distance examination, the interpupillary distance PD ₁ during the near-distance examination becomes smaller than the interpupillary distance PD ₂ during the long-distance examination, and the eye to be examined 12,1
2' virtual optical axes 0 ₁ , 0 ₁ ' are measurement optical systems 16, 1
6' is off the optical axis 0,0'. However, in this way, the virtual optical axes 0 ₁ , 0 1 ' of the eyes to be examined 12, 12' in the close-range examination are the optical axes 0, 0 ₁ ' of the measurement optical systems 16, 16'.
Even if it deviates from 0', the first and second prisms 18, 1
By appropriately selecting the refractive power of 9 according to the interpupillary distance of the subject, the optical axis of the subject's eyes 12, 12' is aligned with the measuring optical system 1 by the refractive action of the first prism 18.
6 and 16', and this optical axis 0, 0' converges on the viewing table 14 at a predetermined viewing distance C due to the refraction action of the second prism 19. In the embodiment described above, the spherical lens means 20
and the transparent window 13 and between the cylindrical lens means 22 and the transparent window 15.
Although an example in which 8 and 19 are provided is shown, the present invention is not necessarily limited to this. For example, as shown in FIG. 2, the first prism means 25 is configured such that a plurality of prisms 23 having different degrees of refraction are arranged at intervals in the circumferential direction on the peripheral edge of a disk 24.
8, and the rotary prism 26, which is the second prism means, may be replaced with the second prism 19. The rotary prism 26 is composed of a pair of ring-shaped prism plates 27 and 28, and the degree of refraction can be arbitrarily changed by rotating the ring-shaped prism plates 27 and 28 relative to each other. Such a disk 24 of the first prism means 25 and a ring-shaped prism plate 2 of the rotary prism 26
7 and 28 are rotatably driven by a pulse motor (not shown). In this embodiment, the measurement optical systems 16 and 16' without the spherical lens means 21 and 21' are arranged in one lens housing 29, and this lens housing 29
Transparent windows 13, 13', 15, 15' are provided in the. Further, in the embodiment described above, the cylindrical lens means 22 is composed of one disk 22a provided with a plurality of cylindrical lenses 22b, but the present invention is not necessarily limited to this. For example, the variable cross cylinder may be replaced with the cylindrical lens means 22. (Effects of the Invention) As explained above, in the present invention, the first prism means whose base direction is opposite to the center side between the two lens means is placed near the eye placement side of the lens means. Since the second prism means is disposed near the viewing surface side of the lens means, the second prism means whose base direction is directed toward the center between the two lens means, does not cause convergence of the lens housing. It is possible to perform a short-distance test, and it is possible to always converge at the same position regardless of the size of the interpupillary distance, and also to perform a short-distance test even in the case of a subject with a very small interpupillary distance.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing one embodiment of a subjective optometry device according to the present invention. FIG. 2 is an explanatory diagram showing another embodiment of the subjective ophthalmoscope according to the present invention. FIG. 3 and FIG. 4 are explanatory diagrams showing a conventional subjective ophthalmoscope. FIG. 5 is an explanatory diagram showing the relationship between interpupillary distance and gaze distance when a conventional subjective ophthalmoscope is used. 11, 11'...Lens housing, 12, 1
2'...Eye to be examined, 14...Visual table, 16,16'...
Measurement optical system, 17, 17'... Lens means, 18
...First prism means, 19... Second prism means, 25... First prism means, 26, 26'...
...Rotary prism (second prism means).

Claims (1)

[Claims] 1. In a subjective ophthalmoscope in which a pair of lens means for measuring refractive power are disposed on the left and right sides, a first lens whose base direction is opposite to the center side between the two lens means. A prism means is disposed near the eye-to-be-examined side of the lens means, and a second prism means whose base direction is directed toward the center between both the lens means.
A subjective ophthalmoscope characterized in that a prism means is disposed near the viewing table arrangement side of the lens means. 2. The subjective ophthalmoscope according to claim 1, wherein at least one of the first and second prism means is a variable prism whose refractive power can be changed. 3. Claims characterized in that a pair of left and right measurement optical systems each consisting of the lens means and first and second prism means are provided, and the distance between the optical axes of the two-sided fixed optical systems is provided so as to be adjustable. The subjective ophthalmoscope according to item 1 or 2.