JP2002209851A - Ophthalmometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely measure the space frequency characteristics and the hue of a visual sense. SOLUTION: A lens 2 and a liquid crystal target 3 are arrayed on the optical axis of an eye to be tested E, a peripheral visual field 4 is provided on the surrounding of the target 3 and a light source 5 is provided in rear of the target 3. In front of the visual field 4, a light source 6 for illuminating this visual field 4 is arranged and an optical sensor 7 for measuring a luminous flux from the target 3 and the visual field 4 is provided. The eye E watches the target 3 illuminated by the light source 5 through the lens 2. In the case of measuring an eyesight, various kinds of target marks are presented to the target 3 one by one. A patient answers the direction of the target mark by falling down the stick 11 of an answering means 9, and his/her eyesight is measured from the size of the smallest target mark answered correctly.

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optometric apparatus used in an ophthalmic hospital or the like.

[0001]

2. Description of the Related Art An optometry apparatus in which an optotype is provided in a box-shaped housing and is shown to a subject to inspect a visual function has been conventionally used.

In this case, the brightness, contrast, color, or the like of the target changes over time, which may affect the accuracy of the inspection. Also, separate devices are used for the color vision inspection device and the visual acuity inspection device, respectively, and the color vision inspection requires an examiner.

Further, the spatial frequency characteristics of vision (MTF: mo
The measurement of a dulation transfer function or contrast sensitivity requires an examiner and cannot be done automatically.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an optometry apparatus which does not change the inspection accuracy even if the brightness, contrast or color of an optotype changes over time. .

It is another object of the present invention to provide an optometry apparatus which can automatically perform a color vision test without an examiner.

It is still another object of the present invention to provide an optometric apparatus that enables a color vision test and a visual acuity test to be performed by the same apparatus.

It is still another object of the present invention to provide an optometry apparatus for automatically measuring a spatial frequency characteristic of vision by changing contrast sensitivity.

[0008]

According to the present invention, there is provided an optometry apparatus for achieving the above object, comprising: an optotype provided inside a housing; and an optical system for a subject to observe the optotype. And an optical sensor provided in the housing for measuring a light flux from the optotype.

In the optometry apparatus according to the present invention, in the optometry apparatus for displaying the stored optotype marks on the electronic image display means and presenting the optotype marks to the subject, the optotype marks and their backgrounds are mutually different. It is characterized by having the same average brightness and different hue.

An optometry apparatus according to the present invention is an optometry apparatus for sequentially presenting stored optotype marks to a subject by an electronic image display means, wherein optotype marks of a predetermined hue are displayed on a background of a different hue. The difference between the hue of the optotype mark and the hue of the background is changed.

The optometry apparatus according to the present invention measures spatial frequency characteristics of vision by changing the frequency and contrast of vertical and horizontal diagonal stripes and sequentially presenting them to the subject by means of electronic image display means to determine the direction. It is characterized by doing.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail based on the illustrated embodiment. FIG. 1 is a configuration diagram of an optometry apparatus according to an embodiment of the present invention, which is capable of automatically inspecting visual acuity, visual spatial frequency characteristics, and color vision. A small housing 1 is disposed in front of the eye E, and an optical system and an electric system are built in the housing 1. A lens 2 and a liquid crystal target 3 are arranged on the optical axis of the eye E to be examined. A peripheral visual field 4 is provided around the liquid crystal target 3, and a light source 5 is provided behind the liquid crystal target 3.

The liquid crystal target 3 is an image display member made of a color liquid crystal capable of displaying a video image or the like in which cells are arranged in a matrix, and displays a target mark such as a Landolt ring. A light source 6 for illuminating the peripheral visual field 4 is disposed in front of the peripheral visual field 4. Further, an optical sensor for measuring the light flux from the liquid crystal visual target 3 and the peripheral visual field 4 in three colors of R, G and B. 7 are provided.

The control means 8 in the housing 1 has a memory and a computer, and its output is connected to the liquid crystal target 3. The control means 8 is further connected with an optical sensor 7, an eight-way response means 9, and a power switch 10.
Is provided with a stick 11 to which the subject responds by tilting it back and forth, left and right, and a button 12 to be pressed when the subject is unsure.

At the time of optometry, the subject's eye E looks at the liquid crystal target 3 illuminated by the light source 5 from behind through the lens 2. The target marks are sequentially displayed on the liquid crystal target 3 according to the program of the control means 8. The control means 8 determines the response of the subject by the eight-direction response means 9, determines a target mark to be displayed next, and automatically performs eye examination such as eyesight.

FIG. 2 shows a liquid crystal visual target 3 and a peripheral visual field 4. A circular display frame of the liquid crystal visual target 3 is provided at the center of the peripheral visual field 4. In the peripheral visual field 4, a plurality of direction display members 13 composed of LEDs for displaying a direction in which a response is input by the stick 11 are arranged, and the direction display member 13 in the input direction is lit to notify the subject.

At the time of measuring the visual acuity, the target marks L of Landolt rings of various sizes as shown in FIG. The subject responds by tilting the stick 11 of the response means 9 in the direction of the optotype mark L, and the visual acuity is measured from the size of the smallest correct optotype mark L.

In this visual acuity measurement, the example of the target mark L by the Landolt's ring has been described, but a stripe pattern having a high contrast may be used. The discontinuity of the Landolt's ring has a visual acuity of 1 at a visual angle of 1 minute, and corresponds to a visual acuity of 1 when the interval between the stripes is 2 minutes. In this case, stripe targets of various frequencies are sequentially presented, and the visual acuity is determined at the minimum visible pitch.

FIG. 3 shows a fringe target M for measuring the visual spatial frequency characteristic or contrast sensitivity displayed on the liquid crystal target 3. By changing the contrast of the stripe, the extent to which the stripe can be recognized is determined for each frequency. Since any one of the four directions of the stripes is presented sequentially according to the program of the control means 8, the direction is input as a response by the response means 9.

In the case of horizontal stripes, stick 1 on either side
When 1 is defeated, the left and right direction display members 13 are turned on. In the case of vertical stripes, the direction display member 13 lights in two directions at the same time regardless of the direction of the stripes. When the answer is correct, stripes with a lower contrast are presented, and the minimum contrast that can be answered correctly is determined.

The stripes may be displayed vertically and horizontally only. In this case, a uniform optotype without contrast is mixed with the stripe optotype and sequentially presented. When the subject determines that the stripes are not visible or not, he responds by pressing button 12. If vertical or horizontal stripes are seen, the stick 11 is tilted in that direction.

In this way, the minimum contrast visible for each frequency is obtained. The relationship between the minimum contrast and the frequency, which is the pitch of the stripes, is the MTF, and the measured value is displayed together with the range considered as a normal value.

FIG. 4 shows an optotype for color vision inspection. The optotype mark L, which is a Landolt ring displayed on the liquid crystal optotype 3, and its background 3 'have the same brightness and saturation but differ only in hue.
The color discrimination ability is measured by changing the hue. If the difference in hue can be recognized, the target mark L is known, and the direction of the target mark L is input by tilting the stick 11 of the response means 9.

Also, a stripe pattern can be used for color vision inspection. The hue of the stripe target M in FIG. 3 and the hue of the background 3 ′ constitute a stripe pattern. The direction and the color contrast are sequentially changed and presented, and if known, the stick 11 is tilted in that direction to respond.

If the answer is correct, the hue difference is gradually reduced and presented. The smallest difference represents the ability to discriminate in that color,
The discrimination ability is obtained for each of the three colors of R, G, and B. The measured values are displayed on a display device (not shown) together with the range considered as a normal value, but can be used not only for the measurement but also as a training machine for color discrimination.

FIG. 5 shows the liquid crystal target 3 at the time of calibration, and the light source 5 and the liquid crystal target 3 may change after the expiration of the use period of the apparatus, so that the brightness, contrast or hue of the liquid crystal target 3 is changed. Changes and affects the measurement accuracy. In the case of the visual acuity target of FIG. 2, a portion of the target mark L and its background 3 '
The brightness of the portion is measured sequentially. The same signals are sequentially input to the entire surface of the liquid crystal target 3, and the light beam therefrom is detected by the optical sensor 7.

The control means 8 determines whether or not the value measured by the optical sensor 7 is a predetermined value. If not, the input signal to the liquid crystal target 3 is changed to a predetermined value. This calibration is preferably performed automatically when the power switch 10 is turned on.

In the case of the stripe target M for measuring the MTF shown in FIG. 3, the signals of the bright part Ma and the dark part Mb of the stripe when a signal having a predetermined contrast is input are used for the liquid crystal target 3 respectively. The entire surface is sequentially turned on, and the brightness of each is detected by the optical sensor 7 to determine whether or not a predetermined contrast is obtained.

If there is a change due to deterioration of the light source 5 or the like, the input signal to the liquid crystal target 3 is changed and corrected accordingly. The optical sensor 7 is composed of three sensors capable of measuring three colors, respectively, and measures the hues of the optotype mark L and the background 3 ′ separately for R, G, and B, and outputs the R, G,
Control is performed for each B input signal, and calibration is performed so that the hue has a predetermined value. In an apparatus that does not perform a color vision test, the light sensor 7 is used.
May simply be a photodetector that measures the amount of light.

In the above-described embodiment, the automatic optometry apparatus has been described. However, it is needless to say that the present invention can be applied to an apparatus operated and operated by an examiner.

[0031]

As described above, the optometry apparatus according to the present invention can perform optometry with high accuracy irrespective of the secular change of the target or the target illumination light source.

Further, the color vision test can be automatically and quantitatively performed, and the color vision test and the visual acuity test can be performed by the same device.

Further, the visual spatial frequency characteristic or the contrast sensitivity can be automatically measured, and the same device as the optometer can be used.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment.

FIG. 2 is a front view of a liquid crystal target and a peripheral visual field.

FIG. 3 is a front view of a visual target for visual spatial frequency characteristic measurement.

FIG. 4 is a front view of a target for color vision inspection.

FIG. 5 is a front view of the target during calibration.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Housing 2 Lens 3 Liquid crystal visual target 4 Peripheral visual field 5, 6 Light source 7 Optical sensor 8 Control means 9 4-directional response means 13 Direction display member L Optotype mark M Stripe optotype

Claims (9)

[Claims] 1. An optotype provided inside a housing, an optical system for a subject to observe the optotype, and a light provided in the housing to measure a light flux from the optotype. An optometry apparatus comprising a sensor. 2. The optometry apparatus according to claim 1, wherein the optical sensor measures brightness or color of the target. 3. The optometry apparatus according to claim 2, wherein the brightness or the color of the optotype is calibrated. 4. The optometry apparatus according to claim 3, wherein the calibration is automatically performed when a power switch is turned on. 5. An optometry apparatus which displays a stored target mark on an electronic image display means and presents it to a subject.
An optometry apparatus wherein the optotype mark and its background have the same average brightness and different hues. 6. The optometry apparatus according to claim 5, wherein a difference in hue between the optotype mark and its background is sequentially changed and presented to the subject to perform optometry. 7. An optometric apparatus for sequentially presenting stored optotype marks to a subject by an electronic image display means, wherein optotype marks of a predetermined hue are displayed on a background of a different hue, and An optometric apparatus characterized by changing a difference between a hue of a subject and a background. 8. The optometry apparatus according to claim 5, wherein the optotype mark has a direction. 9. A method of measuring spatial frequency characteristics of vision by changing the frequency and contrast of vertical and horizontal diagonal stripes and sequentially presenting them to an examinee by an electronic image display means and letting the subject judge the direction. Optometrist.