JPS6220808B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Conventionally, there are two methods for visual acuity testing and refractive error testing: an objective method and a subjective method, and the final decision is made based on the test subject's visual perception.

Visual acuity charts are roughly divided into two types: stop marks for determining direction and those for identifying shape.Standard optotypes have the shape (size) shown in Figure 1.
Visual acuity is considered to be 1.0 if you can barely see the cut f in the ring from 5 meters away. Other types include kana characters, hiragana, numbers, and romaji, but there are individual differences in visual recognition for all of them, and there are differences in how they are seen (how they answer).
In particular, visual acuity tests for astigmatism show a marked difference in the visual appearance of the optotype, and this is a major problem in the case of children and people with weak appeal, such as the deaf and dumb.

The present invention has been devised and developed to eliminate the above-mentioned damage and enable quick and accurate measurement.The present invention will be explained below with reference to the accompanying drawings.

1 is a pedestal, 2 is a case body above the case body, and 3 is a head case supported by the case body, and the head case has a right-angled refraction hole S inside thereof to project the reflected light of the chart, which will be described below. , S' is provided, and a through hole H having the same diameter as the through hole S is formed in the front surface of the head 4, and a prism housing, a lens frame housing, etc., which will be described later, can be rotated. A bearing plate 5 supported by the bearing plate 5 is integrally fixed.

A light source box 6 is provided in the pedestal 1, and a light bulb 7 as a light source is mounted inside the box, and a chart set case 8 is mounted on its upper surface. The chart set case 8 consists of a filter 9 and a chart 1 with a black circle in the center as shown in FIG.
0 are arranged in combination. Filter 9 here
When the illuminance of the visual target is kept at 400-500 lux,
The light from the optical bulb is bright red, so this is to prevent this, and the black circle chart 1
0 is drawn on a chemically treated opalescent glass plate so that the halo edge of the optotype can be clearly seen.

Reference numeral 11 denotes a plane reflecting mirror provided at the corner positions of the refractive holes S and S' in the head 4, and is used to reflect the optotype of the chart 10 onto the optometry window to be described later.

On the other hand, a part of the bearing plate 5, that is, the left side when viewed from the front (see FIGS. 5 and 6), is formed into a boss receiver E that slightly protrudes toward the front. A prism housing 12 is vertically disposed in front of the bearing plate 5 so as to form a certain space 13. Two prisms P 1 and P ₂ are placed inside the prism housing 12 at positions corresponding to the through holes S and H formed in the head 4 and the bearing plate 5, as shown in FIGS. _7A and B. The prism holder 14 held in a mating manner is rotatably supported, and this rotates the diopter detection dial 15, which is supported on the rear side of the bearing plate 5. When the gear 17 attached to the tip of the dial shaft 16 rotates within the prism housing 12,
In addition, the rotation is also caused by the outer peripheral gear 19 of the prism holder 14 via the gear 18 within the housing.
This is done so that it rotates. Note that 20 is an optometry window having a vertically long slit T provided in front of the prisms P ₁ and P ₂ .

On the other hand, the right position (5th position) when viewed from the front of the bearing plate 5
6), a lens frame housing 21 is attached to the prism housing 12 so as to rotate in an arc within a space 13, and 22 is a supporting shaft thereof. At this time, during optometry measurements to be described later, the lens frame housing 21 holds the necessary optometry lenses and rotates in a circular arc as shown by the dashed line in the figure (see FIG. 6), in the space 13 with the prism housing 12. The prism holder 14 is brought into contact with the rear surface of the prism holder 14, and a through hole F is bored in the corresponding position, and an optometric lens support frame 23 is provided so as to protrude from the housing. The frame 23 is integrally held from inside the housing 21 via a gear 24, and when rotating the axiality dial 25 attached to the support shaft 22 at the rear side position of the bearing plate 5, At this time, a gear 26 provided on the outer circumferential surface of the support shaft 22 is rotated, and the necessary rotation is made to the optometry lens support frame 23 via a gear 27. This rotational operation is mainly used to adjust the axis of the cylindrical lens. Reference numeral 28 denotes an operating knob for rotating the lens frame housing 21 in an arc.

Reference numeral 30 denotes a forehead rest that is placed on the forehead of the subject to hold the face.
A bracket plate 32 is installed at the upper end of the pair of pillars 31a and 31b.
When the handle 33 is moved from side to side in the front position, the forehead rest 30 is moved from side to side in the same way as when the handle 33 is moved from side to side, so that eye examination operations can be easily performed alternately from side to side. Reference numerals 34a and 34b are holding stays that connect the bracket plate 32 and the forehead rest 30, and when the gear 35 is appropriately rotated at the rear position of the bracket plate 32, the holding stays 34a and 34b move slightly in the front and back direction. I'm starting to feel like I'm being forced to do that.

Reference numeral 36 is a bellows plate for preventing unwanted light, which is attached to the rear surface of the forehead rest 30, and has a pair of slits 37a,
37b is perforated, and prevents light from entering from above or from the side together with the forehead rest 30 during optometry, and protects the prisms P ₁ and P ₂ in the prism holder 14.
The optotypes projected on the surface are made easy to see. Note that the distance between the slits is determined according to the pupil distance of the optometrist, and the distance between the slits is determined by gripping the bracket plate 32 at both sides of the bracket plate 32.
8a, 38b can be rotated as appropriate via a drive mechanism (not shown).

39 is a chin rest, and one of the supporting legs 40a and 40b supporting the chin rest 40a is a support 31a.
The other one 40b is supported in a slidable state by the support 31b.
The jaw position is screwed onto the slide ring 42 and can be moved up and down within a certain distance by rotating the grip 41, so that the jaw position can be freely adjusted according to the patient's eye during optometry. It's summery. In the drawing, 43 is a power switch, 44 is a switch fuse, 45 is a light amount adjustment dial, and 46 is a buzzer.

Next, the effect will be explained. First, turn on the power switch 43. Next, the subject placed their chin on the chin rest 3.
9 and rotate the grip 41 appropriately so that both eyes correspond to the slits 37a and 37b. At this time, the handle 33 is moved to the left or right to move the forehead rest 30 to the left or right. For example, if the handle 33 is moved to the left, the slit 37a and the prism holder 14 When the slit 37b and the optometry window 20 are aligned, the right eye can be examined. Conversely, if the slit 37b is moved to the right, the slit 37b and the optometry window 20 are aligned, and the left eye can be examined. It's like that.

Thus, when the subject turns his face toward the forehead rest 30, the chart 1 in the chart set case 8 illuminated by the optical bulb ₇ is illuminated on the prisms P1 and _P2 of the optometric window 20.
The optotype at 0 is refracted by the plane reflector 11, and the prism
It appears as a virtual image with two halo edges bordering the P ₁ and P ₂ joint. At this time, adjust the prism so that the two halo edges form a point contact at the junction of prisms P ₁ and P ₂ , which corresponds to emmetropia.
The prisms P ₁ and P ₂ are designed so that the Δ° diopter (reflection angle) of each prism and the outer diameter of the chart 10 match. Therefore, the two halos do not focus and form parallel rays at infinity, and the eye to be examined does not have accommodation even at short distances, making it extremely compact.

FIG. 8 illustrates the image formation state of an optotype on the retina of the subject during optometry measurement, and A is the image formation state of the emmetropic eye. Here, the halo of the chart 10 that is visually recognized by the subject is 10', 10'', and the eyeball 4
7 In the inner retina R, both appear as a coincident point of contact g. However, the diopter detection dial 15
When you hold it in your hand and rotate it to the right or left as appropriate, if you do this, the halo 1 will turn as shown in Figure 9A.
0'' rotates around the halo 10' in a point-contact manner, the optometrist is emmetropic and has no problems at all.

By the way, FIG. 8B shows the case of myopic eyes, and the halos 10' and 10'' are imaged in a partially overlapping state.Therefore, when holding the diopter detection dial 15 in your hand, you can rotate it to the right or left. When the eye is rotated in the appropriate direction, if it looks as shown in FIG. 9(b), it is myopic simple astigmatism, whereas if it looks as shown in FIG. 9(c), it is myopic double astigmatism.

Next, Figure 8C shows the case of hyperopic eyes, with halo 1
0' and 10'' are imaged separately without contacting each other. Therefore, when holding the diopter detection dial 15 in your hand and rotating it appropriately to the right or left, the image shown in FIG. When it looks like D, it is hyperopic simple astigmatism, whereas when it looks like E in the figure, it is hyperopic double astigmatism.

In the present invention, since it is visually recognized as described above, the optometric lens support frame 23 is
A concave-convex lens or an ametropia-correcting lens is inserted into the lens, and the power of each lens is gradually increased until the halo can be seen as a point contact as shown in Figure A.

In this device, a vertically long slit T is bored in the optometry window 20 in order to correctly position the examinee's pupil in the center of the prisms P ₁ and P ₂ during optometric examination, and therefore two halos 10' and 10'' are formed. If the halo is shifted in any direction, the outer periphery of the halo will appear chipped, allowing the subject to easily visually recognize the correct halo.

When measuring according to the present invention, in order to eliminate psychological preconceptions of near-sighting in the case of young people who have strong accommodation ability, two black circles of the same shape as the chart 10 are placed in milky white as shown in Fig. 10 before the measurement. A model 48 enlarged and painted on an acrylic board is positioned 3 to 5 meters behind this device, and a hint is given to the user to look at the model 48.
By psychologically looking into the distance, self-adjustment is suppressed and a high correction value can be obtained.

The present invention is constructed as described above, and the location of refractive error is determined by visually recognizing the state of contact between two halo images, and such a simplified visual chart is extremely difficult to visually recognize. This method is easy to use, and accurate visual recognition can be obtained regardless of differences in knowledge or individual differences among subjects. In addition,
The buzzer 46 is intended to enable children and deaf-mute persons to notify the above-mentioned visual discrimination by using the buzzer 46. In addition to immediately obtaining a correct response, it also enables rapid and accurate measurement. This results in less fatigue for the operator and allows for more accurate judgment.

[Brief explanation of the drawing]

FIG. 1 shows a conventional standard optotype, FIG. 2 shows a chart used in the present invention, FIG. 3 is a front perspective view of the entire device, and FIG. 4 is a vertical side view.
Figures 5 and 6 are partially cutaway plan views and front views of the prism holder and lens frame housing portion, Figures 7A and B are perspective views and longitudinal sectional views of the prism holder, and Figures 8A, B, and C. Figure 9 shows the image formation state when the subject is emmetropic, myopic, and hyperopic; Figure 9 A, B, C, D, and H show examples of judgment criteria based on how the chart appears; Figure 10 is an enlarged model of the same shape as the chart. DESCRIPTION OF SYMBOLS 1... Pedestal, 2... Case body, 3... Head case, 4... Head, 5... Bearing plate, 6... Light source box, 8... Chart set case, 9...
... Filter, 10 ... Chart, 11 ... Plane reflector, 12 ... Prism housing, 14 ...
Prism holder, 15... Diopter detection dial,
17, 18, 19...Gear, 20...Optometry window, 2
3...Optometry lens support frame, 25...Axis dial, 30...Forehead rest, 31a, 31b...Strut, 3
3...Handle, 37a, 37b...Slit,
39... Chin rest, 41... Grasp, 43... Power switch, 46... Buzzer, 47... Eyeball.

Claims (1)

[Claims] 1 Consists of a pedestal with a built-in light source and a chart, a case body on the pedestal, and a head case supported by the case body, and a head with a refractive hole and a flat reflecting mirror are provided in the head case, and A bearing plate is provided on the front surface of the head to attach a prism housing and a lens frame housing, and the prism housing is rotatably provided with an optometry window having a vertical slit and a prism holder having two prisms. In addition, the lens frame housing holds the optometry lens necessary for optometry measurements, and is configured to rotate in an arc and come into contact with the rear surface of the prism holder. A visual acuity testing device characterized in that a chin rest is arranged so as to move slightly in the front-back and up-down directions.