JPH035168B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a subjective refractometer.

Conventionally, a refractive power test optotype is shown to the examinee through a pair of corrective optical systems for both ophthalmometric measurements, which are configured to convert the refractive power, and the corrective optical system changes depending on the examinee's response. A so-called subjective refractive power measuring device is known that corrects the refractive power by using the corrected value and measures the refractive power of the eye to be examined. In addition, for this type of device, when performing distance refraction measurement, the refractive power test optotype is placed approximately 3 to 5 meters away from the subject, and this refractive power test optotype is passed through the corrective optical system to the test subject. It is also known that the lens is constructed so that it can be sighted by a person.

However, such conventional devices require a wide range of space because the above-mentioned measurement distance is required when measuring distance refraction, and when measuring near refraction, a refractive power test sight corresponding to the measurement distance is required. There was a drawback that it was necessary to place markers.

In order _to eliminate _such drawbacks, _for example _, as _shown in FIG _. , an apparatus was proposed in which corrective optical systems q ₁ and q ₂ were interposed between projection lenses L ₁ and L ₂ and eyes E ₁ and E ₂ to be examined, respectively. Note that subscripts 1 and 2 indicate the right eye and left eye, respectively.

According to such a configuration, the optotype is used during distance refraction measurement.
A correction optical system converts the light beams from P ₁ and P ₂ into parallel light beams.
q ₁ and q ₂ are passed through, thereby projecting the optotypes P ₁ and P ₂ onto the eyes e ₁ and e ₂ to be examined. The optotypes P ₁ and P ₂ will be placed at focal positions f ₁ and f ₂ of the projection lenses L ₁ and L ₂ . Furthermore, the chief rays of the light beams from the optotypes P ₁ and P ₂ are parallel to each other, and the subject's binocular visual axes are in a far-sighted state. On the other hand, when measuring near refraction, an optotype image is formed at a position of, for example, 30 cm in front of the eyes, and measurements are performed using this optotype image as if the optotype existed at that position. In the configuration of the device, the visual targets P ₁ , P ₂
Even if the subject's binocular visual axes are kept in a parallel state even if the subject's binocular visual axes are moved along the optical axis, it is not possible to create an actual state of near vision. Therefore, when measuring near refraction, in order to manipulate the declination of the visual axes of both eyes, a declination prism is placed in front of the eyes so that the subject's visual axes match at the target image formation position. This is used to convert the binocular visual axes (hereinafter referred to as convergence) to create a near vision condition.

However, with such conventional means of resolving the shortcomings, it is necessary to insert a declination prism into the optical path one by one when measuring near refraction, and it is also necessary to change the amount of prism declination depending on the near distance. In addition to the above-mentioned complexity, this also resulted in deterioration of measurement efficiency. In addition, by inserting a declination prism,
Another drawback was that it was not easy to achieve a convergence state that suited each individual subject.

The present invention was made in order to eliminate the drawbacks of the conventional apparatus, and it is possible to extremely easily and appropriately create a convergence state of both eyes not only for distance refraction measurement but also for near refraction measurement. It is an object of the present invention to provide a subjective refractometer that is capable of measuring refractive power with high precision in a state of natural vision.

Embodiments of the present invention will be described below with reference to FIGS. 2 and 3. In the figure, reference numeral 1 is a light source, and the light flux from this light source 1 is transmitted through the condensing lens 2.
The optotype 3 for refractive power measurement is illuminated through. Various optotypes 3 are arranged on the outer periphery of a rotatably supported disc 4, and can be selectively inserted into the optical path depending on the purpose of measurement.
Furthermore, the light flux from the optotype 3 passes through the correction optical systems 6 ₁ and 6 ₂ via a group of projection lenses 5 and is transmitted to the eyes E ₁ and E ₂ to be examined.
The light is projected onto each pupil of the child.
Here, the correction optical systems 6 ₁ and 6 ₂ are configured as a pair,
The refractive power can be changed by selecting lenses 8 ₁ and 8 ₂ attached to appropriate positions on the outer peripheries of rotating disks 7 ₁ and 7 ₂ , respectively. In this way, the examiner rotates the rotating discs 7 ₁ and 7 ₂ according to the test subject's response, inserts the lenses 8 ₁ and 8 ₂ into the optical path to obtain an appropriate corrective refractive power, and then inserts the lenses 8 ₁ and 8 ₂ into the optical path. The refractive power of the eye to be examined can be measured from the refractive power value.

In addition, the light source 1, the condensing lens 2, and the optotype 3 can be moved integrally, and for example, the optotype 3 can be moved from the front focal position _F0 of the projection lens 5 to the projection lens 5.
Near refraction measurement is carried out by moving the optotype 3 toward the front side, and the optotype 3 can be returned to its front focal position F ₀ during distance refraction measurement.

Next, the arrangement and light flux state of the projection optical system using the projection lens 5 and the correction optical systems 6 ₁ and 6 ₂ will be explained based on an example of specific data. In addition, in order to simplify the illustration, the lenses 5 ₁ , 8 ₁ , 8 ₂ of each optical system are
FIG. 3 shows a thin lens in which the front principal point position and the rear principal point position coincide with each other.

In the figure, the luminous fluxes M ₁ and M ₂ indicated by two-dot chain lines are for distance refraction measurement, and the luminous flux indicated by a solid line
Q ₁ and Q ₂ are for near refraction measurement. in this case,
It is assumed that the corrective optical systems 6 ₁ and 6 ₂ are set to the refractive power of the O diopter. And the projection lens 5
The focal length F is 200 mm, and the distance l between the projection lens 5 and the correction optical system 6 ₁ , 6 ₂ is 200 mm, which is the same as the focal length F.
It is set to mm. In addition, correction optical systems 6 ₁ , 6 ₂
The distance m between the corneal positions P ₁ and P ₂ of the eyes E ₁ and E ₂ to be examined is
It is set to 12mm and is the same as the position where the subject wears the glasses.

In the case of distance refraction measurement, the optotype 3 is placed at the front focal position F ₀ of the projection lens 5, and the light beam from the optotype 3
When M ₁ and M ₂ pass through the projection lens 5, they become two mutually parallel light rays and reach the eyes E ₁ and E ₂ to be examined. In this case, the refractive power of the eye to be examined is O diopter.

On the other hand, in the case of near refraction measurement, the optotype 3 is moved toward the projection lens 5, and the optotype 4 is placed at the near measurement optotype position F ₀ in front of the projection lens 5. Thereby, the two principal rays from the optotype reach the eyes E ₁ and E ₂ to be examined through the projection lens 5 at a convergence angle θ. Thereby, the subject can aim in a so-called near natural vision state as if the optotype 3 were placed at a position m that is a distance n forward from the glasses-wearing position. Note that the optotype position ₀ is located in front of the projection lens 5 by a distance, but in this embodiment, the distance is set to 67 mm, and the distance n, which is the virtual image position of the optotype 3, is set to 300 mm.

The above explanation deals with the case where the refractive power of the corrective optical systems 6 ₁ and 6 ₂ is set to the O diopter and the eye to be examined is measured using the O diopter, but it is of course possible to measure other refractive powers.

As explained above, according to the present invention, the diameter of the optotype for refractive power testing can be projected onto the pupils of both eyes to be examined.
Two projection lens systems are provided, a pair of corrective optical systems for both eyes are placed behind the projection lens system, and the optotype for refractive power testing is configured to be movable along the optical axis. By easily creating an appropriate convergence state during refraction measurement, the subject can always be examined in a state of natural vision in both distance and near refraction measurements. In addition, if the corrective optical system is placed at the back focal position of the projection lens system, the subject's visual angle will always be constant during both distance and near refraction measurements, and the visual angle will change depending on the measurement distance. There is no need to change the measurement efficiency, which improves measurement efficiency.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram explaining a conventional subjective refractometer, FIG. 2 is a sectional view of an optical system showing an embodiment of the present invention, and FIG. FIG. 3 is a schematic diagram showing the state of the light flux of the optical system during measurement of refraction for vision and near vision. 3... Optotype for refractive power test, 5... Projection lens,
6 ₁ , 6 ₂ ... Corrective optical system, E ₁ , ₂ ... Eye to be examined.

Claims (1)

[Scope of Claims] 1. A refractive power testing index that is movable with respect to the eye to be examined, and a group of projection optical systems set to an aperture that can project the luminous flux from the index onto at least the pupils of both eyes to be examined. , a pair of corrective optical systems configured to be able to change the refractive power and arranged behind the projection optical system, and the index is placed at the front focal position of the projection optical system during distance refraction measurement. The self-awareness is characterized in that, when measuring near refraction, the index is moved along the optical axis of the projection optical system from the front focal position side of the projection optical system to the side approaching the projection optical system. type refractometer. 2. The subjective refractometer according to claim 1, characterized in that a correction optical system is disposed at the rear focal position of the projection optical system.