JPH0556922A - Ophthalmometer - Google Patents

Abstract

PURPOSE:To allow ophthalmometry with high accuracy without depending on the diameter of the patient's pupil. CONSTITUTION:The luminous flux from a spotty light source 6 projects a spot light flux to the eyeground Er of the eye E to be examined through a central aperture diaphragm 4, a bored mirror 3, etc. The light reflected from the eyeground Er is reflected by the bored mirror 3 and projects 6 pieces of luminous fluxes to a two-dimensional array sensor 11 through a aperture diaphragm 7, a variable aperture diaphragm 8, a luminous flux separating prism 9, etc. The ophthalmometric value is determined from the luminous flux positions on this sensor 11. The variable aperture diaphragm 8 and the diaphragm 7 exist in the positions conjugate with the pupil of the eye E to be examined. The variable aperture diaphragm 8 selects the apertures of different diameters by a step motor 13 and regulates the outside diameter of the diaphragm 7, thereby determining the diameter of the luminous flux reflected from the eyeground to be measured. The diameter of the pupil is measured from the anterior eye image of the eye E to be examined picked up by a television camera 15 and the aperture of the variable aperture diaphragm 8 is so selected as to attain the adaptable measuring luminous flux.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an eye refractometer used in eye clinics and eyeglass stores.

[0002]

2. Description of the Related Art In measuring the refractive power of an eye by projecting a light flux onto the fundus and using the reflected light flux from the fundus, conventionally, the diameter of the light flux projected onto the fundus or reflected from the fundus is constant.

[0003]

Therefore, when the subject is young, the pupil diameter may be large and the subjective and objective refraction values may not match. Further, when the subject is an elderly person, since the pupil diameter is small, a part of the light flux is eclipsed by the iris and does not reach the fundus, which causes an error.

An object of the present invention is to provide an eye refractometer capable of performing highly accurate measurement in both a young person with a large pupil and an elderly person with a small pupil.

[0005]

An eye refractometer according to the present invention for achieving the above-mentioned object is an eye refractor which projects a light beam on a fundus and receives the reflected light by a photoelectric sensor to obtain an eye refraction value. It is characterized in that the meter is provided with a diaphragm for varying the diameter of the measurement light beam at a position conjugate with the pupil of the eye to be inspected.

[0006]

In the eye refractometer having the above-mentioned structure, the measuring light beam diameter can be changed by the variable diaphragm conjugated to the pupil according to the pupil diameter of the eye to be examined, so that the measuring light beam in the pupil can be prevented from being shaken.

[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 first embodiment, in which a light splitting member 1, a lens 2, a perforated mirror 3, and a pupil Ep of the eye E to be examined are conjugated on an optical path O1 extending in front of the eye E to be examined. As shown in FIG. 3, a single aperture stop 4 having a central opening 4a, a lens 5, and a point light source 6 such as an LED that is conjugated to the emmetropic fundus of the eye E to be inspected are sequentially arranged.

A light receiving portion is provided on the optical path O2 in the reflection direction of the perforated mirror 3, and a multi-hole diaphragm 7 having six openings as shown in FIG. 3, a variable diaphragm 8, and six as shown in FIG. Beam splitting prism 9 composed of a wedge prism, lens 1
0, a two-dimensional array sensor 1 conjugated to the emmetropic fundus of the eye E 1
1 are sequentially arranged, and the output of the sensor 11 is connected to the arithmetic unit 12. Here, as shown in FIG. 5, the variable diaphragm 8 has a fan shape having three openings 8a, 8b, 8c having different diameters, and is driven by a step motor 13. The diaphragm 8 is substantially conjugate to the pupil Ep of the eye E to be examined.

An anterior ocular segment observation system is provided on the optical path O3 in the reflection direction of the light splitting member 1, the lens 14 and the television camera 15 are sequentially arranged, and the output of the television camera 15 is sent to the signal processor 16. Further, the output of the signal processor 16 is connected to the step motor 13 and the television monitor 17.

The light beam emitted from the light source 6 passes through the diaphragm 4, the perforated mirror 3 and the like to project a spot light beam onto the fundus Er of the eye E to be examined. The reflected light from the fundus Er is reflected by the perforated mirror 3, passes through the diaphragm 7, the variable diaphragm 8, the light beam separating prism 9, etc., and becomes 6 light beams as shown in FIG.
1 is received. The eye refraction value is calculated by the calculator 12 based on the position of the light flux image on the sensor 11.

On the other hand, the anterior ocular segment image of the eye E is formed on the television camera 15 via the dividing member 1. The image is combined with the alignment mark M as shown in FIG. It is displayed on the monitor 17. The alignment mark M is a circle having the same diameter as the measurement light beam diameter centered on the optical axis,
The examiner aligns the eye E to be inspected while observing the television monitor 17. The corneal reflection image C of the light source 6 is the television camera 1.
When it comes near the center of 5, the signal processor 16 extracts the signals of the two scanning lines S1 and S2 passing through the pupil Ep as shown in FIG. 7, and from the intersection of the scanning lines S1 and S2 and the contour of the pupil. Find the pupil diameter. Then, the openings 8a to 8c of the variable diaphragm 8 shown in FIG.
Of these, the aperture having the optimum diameter for the pupil diameter is selected. The variable diaphragm 8 plays a role of regulating the outer circumference of the diaphragm 7 and determining the measurement light beam diameter. If any aperture of the variable diaphragm 8 is set, the examiner then presses the measurement switch to perform measurement. I can do it. The relationship between the position of the spot light beam image on the sensor 11 and the eye refraction value changes depending on the measured light beam diameter, but in order to obtain the eye refraction value, it can be dealt with only by changing the calculation constant according to the light beam diameter.

In this embodiment, the diaphragm 7 and the variable diaphragm 8 are overlapped to form a diaphragm for separating light flux. However, a diaphragm having a shape as shown in FIG. You may make it replace with multiple pupils according to a pupil diameter. However, in that case, compared to the method of changing only the outer circumference of the aperture like the variable diaphragm 8, more accurate position control is required. In addition to the method of automatically determining the measurement light beam diameter, the examiner may freely select the light beam diameter. If the size of the alignment mark M is changed according to the aperture diameter of the variable diaphragm 8, the pupil
The relationship between Ep and the measured luminous flux is easy to understand and convenient.

Further, in this embodiment, the alignment mark M
Is generated by a synthetic signal by a computer, but the mark may be optically projected. However, at the stage of capturing the video signal for measuring the pupil diameter, it is easier to perform subsequent signal processing if the information of this mark is not included in the signal.

FIG. 8 is a block diagram of the second embodiment.
The same reference numerals as in FIG. On the optical path O4 extending in front of the eye E to be inspected, the light splitting member 1, the lens 2, the optical member 21 having the mirror portion 21a, the light shielding plate 22, and FIG.
A diaphragm 2 having two openings 23a and 23b as shown in FIG.
3, the variable diaphragm 8, the movable lens 24, and the point light source 6 are sequentially arranged. The light shielding plate 22 is driven by the motor 25, the variable diaphragm 8 is driven by the step motor 13, and the movable lens 24 is controlled by the lens position control device 26. It is designed to be driven by. The diaphragm 23 and the variable diaphragm 8 are conjugated with the pupil Ep of the eye E to be examined. The reflection direction of the mirror portion 21a of the optical member 21 is the light receiving portion, and the lens 10 is provided on the optical path O5, and two photoelectric sensors 27a, 2 are provided as shown in FIG.
A light receiving sensor 27 composed of 7b is arranged, the output of the light receiving sensor 27 is connected to the calculator 28, and the output thereof is connected to the lens controller 26.

In the second embodiment, the motor 25
The light shielding plate 22 driven by the light source 6 shields one of the two light fluxes emitted from the light source 6 and passing through the openings 23a and 23b of the diaphragm 23, and the two light fluxes are alternately examined.
Projected on the fundus Er of As shown in FIG. 10, the reflected light from the fundus Er alternately forms a light flux image 23a ′ from the opening 23a and a light flux image 23b ′ from the opening 23b on the light receiving sensor 27. The outer peripheries of the openings 23a and 23b of the diaphragm 23 are regulated by the variable diaphragm 8 shown in FIG. 9 in the same manner as in the first embodiment, so that the measured luminous flux diameter matches the pupil diameter of the eye E to be examined. .. The position of the movable lens 24 is adjusted by the lens position control device 26 so that the two light flux images 23a ′ and 23b ′ are evenly received by the two photoelectric sensors 27a and 27b. The eye refraction value is obtained from.

[0016]

As described above, the eye refractometer according to the present invention can obtain a highly accurate eye refraction value regardless of the pupil diameter of the subject.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a first embodiment.

FIG. 2 is a front view of a single aperture stop.

FIG. 3 is a front view of a perforated diaphragm.

FIG. 4 is a front view of a light beam separating prism.

FIG. 5 is an explanatory diagram of a variable diaphragm.

FIG. 6 is an explanatory diagram of a spot light flux image on a two-dimensional array sensor.

FIG. 7 is an explanatory diagram of an anterior ocular segment image.

FIG. 8 is a configuration diagram of a second embodiment.

FIG. 9 is a front view of a diaphragm.

FIG. 10 is an explanatory diagram of a light flux image on a light receiving sensor.

[Explanation of symbols]

 6 point light source 7 porous diaphragm 8 variable diaphragm 9 light flux separating prism 11 two-dimensional array sensor 12, 28 calculator 15 TV camera 16 signal processor 17 TV monitor 21 optical member 23 aperture diaphragm 24 movable lens 27 light receiving sensor

Claims (1)

[Claims] 1. An eye refractometer which projects a light beam onto a fundus and receives the reflected light by a photoelectric sensor to obtain an eye refraction value,
An eye refractometer characterized in that a diaphragm for varying the diameter of a measurement light beam is provided at a position conjugate with a pupil of an eye to be examined.