JPH04218137A - Moving object detection contrast threshold inspector - Google Patents

Abstract

PURPOSE:To help in screening for early detection of abnormality of glaucoma, diabetic retinitis and the like by including a stripe target forming means for forming a stripe target on a screen, a contrast switching means of the stripe target, a drive section for vibrating the stripe target and a lighting optical system for lighting the screen evenly. CONSTITUTION:Light from a halogen lamp 1 enters a disc 4 through a condenser lens 2, a stop 3 and a disc 4. The disc 4 rotates with a pulse motor 5 to change a transmission factor. The light transmitted through the disc 4 lights a stripe target plate 7 almost evenly through a projection lens 6. A stripe target drive section 8 vibrates a vibration shaft with one end thereof fixed on the stripe target plate 7 and the other end thereof fixed on a shaft of the pulse motor by normal or reverse rotation of the pulse motor to swing the stripe target plate 7. A projection lens 10 forms a stripe target plate 7 at the center of a screen 13 through a stop 9 and mirrors 11 and 12. Two halogen lamps 14 are arranged on the right and left of an opening to light the screen 13 evenly.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a testing device for testing the visual function of the eye.

0002

BACKGROUND OF THE INVENTION Visual field testing has been conventionally performed as a method for testing eye diseases that cause visual field impairment, such as glaucoma. This visual field test involves positioning the subject's eye in the vicinity of the spherical center of a hemispherical projection screen, and measuring the visual field while changing the presentation location of the optotype projected onto the projection screen. This is what we do. Although this method is also useful as a visual field test, it has been reported that in the case of glaucoma, by the time this test shows that visual field damage has occurred, half of the optic nerve cells have already been lost; It has been desired to detect subjective abnormalities in advance and use them for screening. Furthermore, it has been desired to detect abnormalities at an early stage in diabetic retinopathy and the like, and to utilize this method in screening.

[0003] The present invention was devised based on the above-mentioned requirements, and a technical problem is to provide an inspection device useful for screening by detecting early abnormalities such as glaucoma and diabetic retinopathy. .

0004

[Means for Solving the Problems] In order to solve the above problems, a moving object detection contrast threshold testing device of the present invention has the following configuration. That is, (1) a stripe optotype projection optical system that projects the stripe optotype onto a projection screen, a contrast switching means that switches the contrast of the stripe optotype, a drive section that vibrates the stripe optotype, and a drive section that vibrates the stripe optotype; It is characterized by comprising an illumination optical system that illuminates the screen almost uniformly.

(2) The contrast switching means in (1) is a switchable filter disposed in the stripe target projection optical system or a switching means for adjusting the light intensity of the projection light source for the stripe target. It is a feature.

(3) Projection screen of the fringe target of (1)
It is characterized by its hemispherical shape.

(4) It is characterized by having means for changing the direction of the striped optotype of (1).

(5) The amplitude of the fringe optotype in (1) is characterized by being approximately 1/2 of the fringe pitch.

(6) The moving object detection contrast threshold testing device of (1) is characterized in that a response switch for the test subject is provided.

0010

[Embodiment] Prior to a detailed explanation of the embodiment, the inspection principle on which the present inspection apparatus is based will be explained. Examining the visual function of the eye reveals that there are vertical connections made up of photoreceptor cells, bipolar cells, and ganglion cells, and horizontal connections made up of horizontal cells and amacrine cells. The vertical connections convert the light that reaches the photoreceptor cells into electrical signals, which transmit image information to the brain via the optic nerve. On the other hand, horizontal connections are composed of horizontal cells located between photoreceptor cells and bipolar cells, and amacrine cells located between bipolar cells and ganglion cells, and are responsible for contrast enhancement, motion detection, stereoscopic perception, etc. . This horizontal connection allows humans to accurately see objects under a wide range of illumination ranging from 1 to 1011, and is said to be able to detect even the slightest stain or dirt on a white wall.

[0011] Incidentally, in diabetic retinopathy, it is known that rhythmic wavelets related to lateral function become abnormal at an extremely early stage, and disturbances in lateral function occur in the early stages of visual field impairment. Focusing on the fact that this is estimated to be the case, this device attempts to detect subjective abnormalities in visual function that can be associated with abnormalities in lateral function. in particular,
A striped pattern with an appropriate spacing (the optimal width for one horizontal cell to connect, that is, approximately 200 μm on the retina) is imaged on the retina, and the striped pattern is swayed to provide stimulation. The amplitude of this vibration should be at least 1/2 of the stripe width, and the frequency should be within a range that does not affect the static detection ability (
It is easy to detect if the threshold value (to be described later) is easily set when the stopping distance is 300 mm and the frequency is set to about 4 Hz. The test examines how low the contrast the subject can recognize the movement (fluctuation) of the striped pattern projected at the center of the adaptation field. If horizontal cells and amacrine cells are functioning normally,
It can be recognized even when the contrast is low, below a certain threshold set as the boundary between a normal person and an abnormal person. However, if these do not function properly, the movement of low-contrast striped patterns cannot be recognized. Note that the contrast is expressed by the following formula. Here, A is the brightness of the bright part of the striped pattern, and B is the brightness of the dark part of the striped pattern (brightness of the adaptation field).

[0012] Details of an embodiment of the present invention based on the above measurement principle will be explained with reference to the drawings. Configuration FIG. 1 is an optical system layout diagram showing the configuration of the optical system of the inspection apparatus of this embodiment. Reference numeral 1 denotes a halogen lamp which is a light source of the optotype projection optical system. Light from the halogen lamp 1 enters a disk 4 via a condenser lens 2 and an aperture 3. A wedge-type filter that changes the transmittance steplessly on the projection optical path is arranged on the disk-shaped disk 4, and the disk 4 is rotated by a pulse motor 5 to change the transmittance. Since it is not essential that the transmittance changes continuously, in this example, the transmittance changes stepwise, and the contrast of the stripe optotype is changed in 200 steps in the range of 0.1% to 10%. It is designed to last. Further, the transmittance may be changed by combining filters.

The light transmitted through the disk 4 illuminates the striped optotype plate 7 almost uniformly through the projection lens 6. On the striped optotype plate 7, a striped pattern is drawn in which the transmittance in bright areas is 80% or more and the transmittance in dark areas is 0%. The stripe optotype plate 7 is constructed so that the stripe optotype (see FIG. 2) projected onto the screen 13 has a visual angle of 5 degrees and a stripe pitch of 0.5 degrees. The striped optotype plate 7 is vibrated by the striped optotype drive unit 8 in a direction perpendicular to the stripe direction. The frequency of this vibration is 4Hz and the amplitude is 0.2
It is 5 degrees. The striped target drive unit 8 in this embodiment employs the following simple mechanism in consideration of the fact that the amplitude of vibration is sufficiently small. That is, by vibrating a vibration shaft having one end fixed to the striped optotype plate 7 and the other end fixed to the shaft of a pulse motor, the striped optotype plate 7 is vibrated by the forward and reverse rotation of the pulse motor.
vibrate.

The projection lens 10 includes an aperture 9 and a mirror 11.
, 12, the image of the striped optotype plate 7 is formed at the center of the screen 13. The shape of the screen 13 is hemispherical,
The screen size is 20 degrees, and the gaze distance from the eye to be examined is 3
It is set to 00mm. The screen 13 has a hemispherical shape to facilitate uniform illumination. scree
The front of the screen 13 is covered to block light from the outer periphery, and the subject looks through the central opening at the striped optotype projected onto the screen 13 with his left or right eye. .

Two halogen lamps 14 are arranged on the left and right sides of the opening, and illuminate the screen 13 uniformly. The background brightness of this screen is 500 cd/m2, and the background brightness corresponds to the brightness of the dark part of the striped optotype. It is designed to.

FIG. 3 is a block diagram of an electrical system that controls operations for testing an eye to be examined. The microcomputer 15 controls the halogen lamps 1 and 1 through the lamp driver 16.
14 on/off, pulse motor via motor driver 17
The striped target drive unit 8 is driven by the motor driver 18.
control the drive of each. Patient response switch 19
The signals from the microcomputer 15 are input to the microcomputer 15 for processing. 20 is a printer driver that outputs the test results, and 21 is a printer. 22 is a controller;
It specifies contrast, presentation speed, etc.

Operation FIG. 6 is a flowchart of inspection. Inspection starts
First, the subject's eye is made to look at the screen for 1 to 2 minutes (step 1-1). This is to make the subject's eye photopic. Next, the disk 4 is driven, the contrast of the striped target is set to 10% (step 1-2), and the test loop count is set to 0 (step 1-3). Here, one loop represents one test using one contrast.

When this step is completed, the examiner presses the start switch on the controller 22, and measurements are automatically performed thereafter. Present a stationary stripe optotype (step 1-
4) The subject is asked to respond whether or not the striped optotype is visible to the subject's eye (step 1-5). If the response is correct, proceed to step 1-6; if the response is incorrect, step 1-7
Proceed to.

In step 1-6, the controller 22 is operated to vibrate the striped optotype plate 7 and the subject responds (step 1-8). When the vibrating striped optotype is recognized, Proceed to step 1-9. If this response is incorrect, the process proceeds to step 1-7.

In step 1-9, the contrast of the striped target is lowered by one step. Determine whether the contrast down one step is the lowest contrast (step 1-10), and if the contrast is the lowest, step 1
Proceed to -11.

If the contrast is not the lowest, the inspection rule
Determine whether the count of taps is 10 or more (
Steps 1-12). If the desired detection result is obtained after 10 or more inspection loops, the process proceeds to step 1-11.

If the number of inspection loops is less than 10, it is determined whether the contrast variation range is 0.1% or less (step 1-13). If it is 0.1% or less, it is determined that the test result is correct and the process proceeds to step 1-11. 0.
If it is less than 1%, add 1 to the inspection loop count and proceed to A (step 1-14).

On the other hand, in step 1-7, the contrast is increased by 1/2 step and the process proceeds to step 1-15, where it is determined whether the contrast is at the maximum value, and if it is not the maximum contrast, the process proceeds to step 1-12.

In step 1-11, the test results are printed out. The test results in this example show that the contrast is 1.
It has been clinically confirmed that if the measured value is less than %, it is considered normal, and if it is higher than that, it is considered abnormal.

Although the above-mentioned measurement is performed in auto mode, it is also possible to adopt a method in which contrast settings and the like are set by the examiner. Furthermore, this inspection can be carried out by, for example, placing a rotary prism in the fringe target projection optical system, rotating it to change the direction of the fringes, repeating it several times, and calculating the average of the measured values. , accuracy can be increased.

In the embodiments described above, contrast switching is performed by switching the disk 4 disposed in the stripe optotype projection optical system, but it can also be performed by adjusting the light intensity of the projection light source itself. can. As described above, this embodiment can be modified in various ways, and these modifications are also included in the present invention within the scope of keeping the same technical idea.

[0027]

According to the moving object detection contrast threshold testing device of the present invention, disorders of horizontal functions such as horizontal cells and amacrine cells can be detected at an early stage. Therefore, it can contribute to the early detection of glaucoma, diabetic retinopathy, etc. In particular, since only one test result is required, abnormalities can be easily determined, and it is highly effective in screening for the early detection of these eye diseases. Therefore, it has great utility, such as when it is used in combination with a vision test in the driver's license aptitude test for patients with the same disease.

[Brief explanation of the drawing]

FIG. 1 is an optical system layout diagram showing the configuration of an optical system of an inspection apparatus according to the present embodiment.

FIG. 2 is an explanatory diagram of a striped optotype.

FIG. 3 is a block diagram of an electrical system that controls operations for testing an eye to be examined.

FIG. 4 is an inspection flowchart.

[Explanation of symbols]

1,14 Halogen lamp 2 Condenser lens 3,9 Aperture 4 Disc 5 Pulse motor 6,10 Projection lens 7 Striped optotype board 8 Striped target drive unit 11,12 Mirror 13 Screen

Claims (6)

[Claims] 1. A stripe target projection optical system for projecting a stripe target onto a projection screen, a contrast switching means for switching the contrast of the stripe target, a drive unit that vibrates the stripe target, and a projection system comprising: A moving object detection contrast threshold testing device comprising: an illumination optical system that illuminates a screen substantially uniformly. 2. The contrast switching means of claim 1 is characterized in that it is a switchable filter disposed in the stripe optotype projection optical system or a switching means for adjusting the light intensity of the projection light source of the stripe optotype. A moving object detection contrast threshold testing device. 3. A moving object detection contrast threshold testing device, wherein the projection screen for the stripe optotype according to claim 1 is formed in a hemispherical shape. 4. A moving object detection contrast threshold testing device comprising means for changing the direction of the striped optotype according to claim 1. 5. A moving object detection contrast threshold testing device according to claim 1, wherein the amplitude of the striped target is approximately 1/2 of the striped pitch. 6. A moving body detection contrast threshold testing apparatus, characterized in that the moving body detection contrast threshold testing apparatus according to claim 1 is further provided with a response switch for a test subject.