JPH05199994A - Instrument for measuring refracting power of eye - Google Patents

Abstract

PURPOSE:To enable not only the measurement of the refracting power of an eye but the general ophthalmologic inspections, such as observation of the front eye part and observation of the crystalline lens, by the constitution consisting in arranging a beam splitting member in a lens system and arranging a light source in the position conjugate with an image pickup element. CONSTITUTION:A slit 2, a visible light cut filter 3, a half mirror 4 and an objective lens 3 are arranged on the optical axis from the light source 1 to the eye E to be examined. The image pickup element 6 is arranged behind the half mirror 4 and the slit 2 arranged in the position conjugate with the image pickup element 6 is illuminated by the light source 1 via the half mirror 4. The luminous flux emitted from this slit 2 is made into collimated beams of light by the objective lens 5. The collimated beams of light pass the pupil of the eye E to be examined and form a slit image on the eyeground Ef. The slit image reflected by the eyeground Ef is emitted again from the pupil and forms the image again on the image pickup element 6 through the objective lens 5. The visible light cut filter 3 is a filter having the characteristic to allow the passage of only the IR light and is used to prevent the patient from feeling dazzle and to prevent the miosis.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an eye-refractive-power measuring device for illuminating a fundus of an eye to be examined and observing a reflected image thereof with a video camera to measure an eye-refractive power.

[0002]

2. Description of the Related Art Conventionally, there is no effective measuring means other than the use of a screening method for measuring the eye refractive power of an infant or a bedridden elderly person who cannot use an autorefractometer. However, recently, as disclosed in JP-A-2-154732 and JP-A-2-191428, there has been proposed a method for measuring the eye refractive power of an infant using a photorefraction method. ..

[0003]

However, this conventional example has a drawback that it takes a lot of time to take a picture of a film by the ordinary photorefraction method and to know the result. Further, in order to calculate the light amount distribution of the fundus reflected light on the pupil, the device becomes complicated and large,
It has the disadvantage of high cost.

The object of the present invention is to solve the above-mentioned problems,
An object of the present invention is to provide an eye refractive power measurement device that can perform general ophthalmic examinations with a simple configuration.

[0005]

An eye refractive power measuring apparatus according to the present invention for achieving the above object comprises a measurement chart, a light splitting member, and an optical axis for projecting the chart onto the fundus of the eye to be examined. It is characterized by comprising a lens having a portion movable in a direction and an image pickup element arranged at a position conjugate with the chart through the light splitting member.

[0006]

The eye refracting power measuring apparatus having the above-mentioned configuration measures the eye refracting power with a very simple construction in which the light splitting member is arranged in the lens system and the light source is arranged in a position conjugate with the image pickup device. Therefore, the eye refractive power can be measured very easily and inexpensively.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail based on the illustrated embodiments. FIG. 1 is a configuration diagram of the present embodiment. A slit 2, a visible light cut filter 3, a half mirror 4, and an objective lens 5 are arranged on an optical axis from a light source 1 to an eye E to be inspected.
An image sensor 6 is arranged behind the half mirror 4. The eye E is an emmetropic eye, and the objective lens 5 is the eye E.
The eye fundus Ef, that is, the point at infinity, is focused.

The slit 2 arranged at a position conjugate with the image pickup device 6 via the half mirror 4 is illuminated by the light source 1, and the light beam emitted from this slit 2 is made into a parallel light beam by the objective lens 5 and the eye E to be inspected. A slit image is formed on the fundus Ef through the pupil. The slit image reflected by the fundus Ef exits the pupil again, passes through the objective lens 5, and forms an image on the image sensor 6. The visible light cut filter 3 is a filter having a characteristic of transmitting only infrared light, and is for preventing the subject from feeling glare and preventing miosis.

In this case, as the objective lens 5 and the image pickup device 6, those used in a normal television camera system can be used, and the light source 1 to the half mirror 4 are attached thereto to form an eye refraction measuring device. There is.

FIG. 2 is a schematic diagram showing a state in which a signal from the image pickup device 6 is observed on a television monitor. Since the focus of the lens on the subject at a short distance is actually adjusted to infinity, the anterior segment of the eye E is in a so-called out-of-focus state, but passes through the pupil of the eye E. The slit image S of the returning fundus reflected light forms a clear focus. While observing a television monitor (not shown), the examiner adjusts the focus of the objective lens 5 to the slit image S in the pupil by the adjusting mechanism and reads the distance scale to perform the measurement. Actually, the objective lens 5 is focused on the pupil and the distance is read, then the fundus Ef is focused, and the eye refractive power is calculated from the difference between the two distances.

If the eye E to be examined has astigmatism,
Measure as follows. (1) When the direction of the slit 2 and the astigmatic axis direction of the eye E do not match, the slit image S on the fundus oculi Ef appears to rotate depending on the degree of astigmatism, so the direction of the slit image S is the projection direction. The whole device or the slit 2 is rotated so as to coincide with. (2) After determining the astigmatic axis of the eye E, the refractive power in that direction and the refractive power in the direction rotated by 90 ° are measured. (3) The spherical power and the astigmatic power are calculated from the refractive powers in these two radial directions.

FIG. 3 is a block diagram showing a state of myopia in which the eye E is relatively strong. Although the objective lens 5 is extended toward the eye E to be inspected for focusing, the fundus reflection image of the slit 2 can be clearly observed even in this state.

FIG. 4 is a configuration diagram showing a state in which the fundus oculi Ef is focused on the position of the objective lens 5 exactly, and the slit image projected on the fundus oculi Ef cannot be focused. However, as the inspector moves and is represented by the dotted line,
It suffices to change the distance between the objective lens 5 and the eye E and measure again.

FIG. 5 is a block diagram showing a state of weak myopia in which the fundus Ef is conjugated to the rear side of the examiner, and the objective lens 5 is brought closer to the image pickup device 6 from the state of infinity. To measure by.

Up to this point, the description has been made on the premise that the slit image S is observed and focused, but it is easy to apply the recent automatic technology to recognize the fundus image and perform the focus automatically. Therefore, it is easy to recognize the distance from the lens extension signal to the anterior segment and the fundus Ef and automatically calculate the refractive power.

If the objective lens 5 is a zoom lens, the imaging magnification of the fundus oculi Ef and the image pickup device 6 can be freely selected. Therefore, first, the approximate refractive power is screened on the wide angle side, and further, In the case of detailed measurement, it is possible to obtain an accurate refracting power by setting the telephoto side and performing measurement again.

Further, this apparatus can be used not only for observation but also as a recording apparatus by connecting a television signal obtained by the image pickup device to a video photographing apparatus, so that it can be applied to eye position examination and the like. You can Furthermore, since the illumination system is coaxially built in the main body, an image similar to the trans-illumination method can be obtained by observing with focusing in the vicinity of the pupil, which can be applied to the diagnosis of cataract.

[0018]

As described above, the eye-refractive-power measuring apparatus according to the present invention is not limited to the measurement of the eye-refractive power due to the extremely simple structure of the lens and the slit, and can be used for observing the anterior segment or the crystalline lens. It can be widely applied to general ophthalmic examinations.

[Brief description of drawings]

FIG. 1 is a configuration diagram when an eye to be inspected is emmetropic.

FIG. 2 is a schematic diagram of a monitor screen.

FIG. 3 is a configuration diagram when a fundus reflection image is formed in front of a lens.

FIG. 4 is a configuration diagram when a fundus reflection image matches a lens.

FIG. 5 is a configuration diagram when a fundus reflection image is formed behind a lens.

[Explanation of symbols]

 1 Light Source 2 Slit 3 Visible Light Cut Filter 4 Half Mirror 5 Objective Lens 6 Image Sensor

Claims (5)

[Claims] 1. A measurement chart, a light splitting member, a lens having a portion that projects the chart onto the fundus of the eye to be examined and is movable in the optical axis direction, and a lens that is not conjugated with the chart through the light splitting member. An eye-refractive-power measuring device comprising an image pickup device arranged at a position. 2. The eye refractive power measurement device according to claim 1, wherein the light splitting member is arranged between the lens and the image pickup device. 3. The eye refractive power measurement device according to claim 1, wherein the light source emits only infrared light that does not include visible light. 4. The eye refractive power measuring device according to claim 1, wherein the light splitting member is a half mirror. 5. The eye refractive power measurement device according to claim 1, wherein the lens is a zoom lens.