JPH01158932A - Method and apparatus for searching blind spot in eye of subject - Google Patents

Abstract

PURPOSE: To point a visible field obstacle for very short time by changing luminance of a pixel by high frequency and distributing the pixel in a shape of noise pattern uniformly. CONSTITUTION: A distance between a screen 4 of a video monitor 1 and a jaw supporting element 3 of the screen 4 is defined to have a diameter of 60 degree in the visible range to be diagnosed. The dark point can be recognized the most distinctly when high flicker frequency and a noise area with high contrast and small particle are supplied. Thus, most of diagnoses are conducted by using 50Hz in frequency, a light element with 60cd/m<2> in luminance and a dark element with 0.8cd/m<2> in luminance. The ratio of the dark element to the light element is advantageous for the dark element and is 50% or 70%. In the test area not only noise area and polar coordinates are appeared, but also an even area for conventional vision measurement can be expressed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method and apparatus for searching for a scotoma in a patient's eye.

In conventional technical visual field examination, differences in light sensitivity from one retinal location to another are examined. In this case, two different methods are known, one of which is dynamic perimetry, in which the examination is performed with moving inspection marks, and the other is static perimetry. ,
In this static perimetry, differences in light sensitivity are precisely measured at fixed locations starting from dark luminance. Currently, multiple computer supported systems are used, in which
It operates using the so-called Lascou perimetry method. In this case, the examination point raster is automatically scanned according to a program, in this way matched examination point brightness or accurate threshold measurements are measured, and these measurement results are then stored and used at the end of the examination. printed on. Locations where nothing is perceived or where the light sensitivity difference is reduced are identified separately. The outcome of the examination is better the earlier such defects are detected.

For visual field examination, spherical perimetry is often used, in which the examination point is projected onto a sphere via an adjustable projection system or a diode or glass fiber light transmission. If the body is attached to the sphere, j′,
ing. All these known systems are expensive and mechanically very sensitive, since the demands on accuracy are very high.

A multi-field examination method is known from U.S. Pat. It contains a regular arrangement of pixels in the form of a restricted pattern. This pattern, which is small compared to the total area of the pixels, has regularly spaced and identical density of points, which differ both in arrangement and density from the points in the noise image.

This geometrically arranged dot pattern is shifted across the entire image to examine scotomas or similar visual defects. In this way, a scan of the subject's central visual field is performed for 30
will be carried out until This method was also found to be inadequate, as it is expensive and requires longer examinations (more of the entire field of view has to be scanned).

The problem with all of these visual field examinations is that the subject himself or herself cannot confirm whether a visual field defect is present. Therefore, the entire retina must be examined in each examination. If it is known at the beginning of the examination that such visual field defects are to be expected, the examination can be made much easier and faster.

Problems to be Solved by the Invention The problem of the present invention is to provide a method and device for searching for a scotoma in the eyes of a subject, which allows the subject himself or herself to point out such visual field defects in a very short period of time. Our goal is to provide the following.

Means for Solving the Problem The object described above regarding the device is solved by the features set out in the characterizing part of claim 1, and the problem described regarding the method is solved by the features mentioned in the characterizing part of claim 1.
Effects of the invention solved by the features described in the feature section of claim 15 Therefore, according to the present invention, the eyes of the subject 7 are closely adjacent to each other on the screen and the brightness is continuously alternating. An image consisting of a number of points is provided, this image additionally having fixation points for the eyes. The alternation of brightness of individual pixels may be irregular or periodic. A simple device for performing perimetry examinations is a high-resolution video monitor, which contains a large amount of noise with very small particles, similar to the noise area that appears when a disturbance occurs in a television. It has a regularly flickering surface. The subject's eyes are located at a predetermined distance from the video screen, with the eyes fixed at a predetermined fixation point on the image screen. The subject can immediately confirm where the scotoma is present by looking at the noise area.

The pathological scotoma described above is where the patient sees, instead of a uniform surface, a bright and dark surface that flickers at a high frequency due to small particles, similar to the noisy areas that appear on a television monitor that is turned on and receives a program. This allows for clearer viewing. When the patient's gaze is fixed on a clearly visible point in the center of the television screen or programmed into it, there is little or no flickering, and the surroundings and brightness are Appears as a markedly different surface. The observer can trace the border of the scotoma on the television screen with a finger. This marking of one's own darkening is often done spontaneously, since limited "clouds" within the noise area
This is because it leaves a strong impression on patients. Absolute scotomas of all bases caused by damage to the retina or optic nerve or optic chiasm or optic tract can be pointed out by the patient in a manner similar to the damage caused by glaucoma, with temporary In general, it remains to be seen whether scotomas are perceived as brighter or darker clouds. However, in any case, a scotoma is distinguished by the fact that within the region of the scotoma, flicker in the noise area is perceived to be absent or less compared to the surrounding area.

The prerequisites for the reproducible perception of the scotoma by the patient and the rapid perimetry, measurement control and registering of the perceived visual field defect are standardized, computer-generated, only parameters that can be changed. It is a video monitor that can present both a certain noise area and a contourless surface with inspection points that are freely movable and can be selected as either bright or dark points. Furthermore, it is advantageous to insert a visual field diagram with a power display on the video monitor in order to ascertain the location and extent of the obstruction.

It is possible in a very simple way to combine the perception of a scotoma in a noise area with a tedious perimetry examination as a test area on the screen of the same monitor. In doing so, perceiving the scotoma within the noisy area is the first orienting test that quickly informs the ophthalmologist whether and where a defect is present within the visual field, i.e. Serves as a screening method. A conventional type of manual dynamic perimetry or automatic raster perimetry can then be performed within the scotoma region. The advantage of such a two-pronged method is that
The visual field measurement only needs to be carried out within the defective area, thus significantly saving time compared to conventional methods.

The simultaneous use of high-resolution video monitors for both noise area and regular perimetry allows for accurate comparison of the obtained examination results. Contrast and brightness and color can be varied in similar ways in both examination methods. In this case, both dynamic and static perimetry can be carried out manually, with free movement, or automatically.

In this case, the form of the planar perimetry method can be perfectly matched to the shape and size of the visual field defect previously detected by noise area perimetry. In this way,
The advantages of rapid scotoma detection can be combined with the accuracy of a situation-adapted planar perimetry method.

Depending on the size of the video monitor, the viewing area to be examined is obtained. This viewing area is 60° on a typical video monitor.

However, this viewing area can be enlarged by shifting the fixation point.

It has been found to be very advantageous to project the noise area into the perimetry sphere, since in this way the advantages of the two-pronged perimetry method and the full hemispheric perimetry method can be realized. This is because it can be executed in the form of

In the device according to the invention, it is particularly advantageous if the brightness compensation of the image or image screen can be carried out at predetermined measurement points.
It turned out to be an advantage. This compensation can be carried out, for example, with a photodiode, the current flowing through the photodiode being used as a measure of the brightness of the picture screen. This compensation can be done continuously or at regular intervals during the visit. Therefore, accurate brightness levels can be adjusted and tested to obtain reproducible examination results. With the present invention, it is also possible to perform brightness compensation in many pixels.

With the device of the present invention, it is also possible to display a noise pattern only in visual field areas that are already recognized as visually impaired by the subject. If the remaining images do not show noise and the subject declares that all images do not display noise, it is proven that there was no visual field defect.

In order to ensure that the noise image appears only on predetermined surfaces, the device is equipped with a light pen or a mouse or a touch screen.

In the present invention, the fixation point is adjusted by shifting the image in order to align the fixation point with the position of the subject's eyes. This shift can be carried out by means of an arithmetic program, during which the subject's eyes are provided with, for example, a coordinate system. The advantages offered by this adjustment method are that
There is no need to use a device to fix and adjust the subject's head. Furthermore, adjustment of the fixation point can be accomplished much more quickly and easily.

With the present invention, it is possible to vary the diameter of the pixels so that a subject with visual impairment can recognize the individual pixels. Further, according to the invention, it is possible to vary the color of the pixels or to change the color in order to prevent the subject's eyes from adapting to the noise area. Furthermore, it is possible to vary the intensity alternation frequency of the pixels to eliminate patient habituation. When changing the color of a pixel, it is also possible to simultaneously test the subject's visual perception of color.

In the apparatus of the present invention, it is possible to inspect the position of a dark spot by switching the brightness of each pixel between positive and negative.

In the present invention, for example, sequences of numbers are inserted into images controlled by a computer, and the subject points out which one or more digits in these sequences he can see. This allows the fixation point to be determined, allowing the patient to easily fixate his or her eyes. This fixation control can be achieved by aligning the fixation point or region with a blind area where the subject cannot see anything. In this case, this fixation point or fixation area,
The area, ie the size of the fault image produced by the computer, is slightly smaller than the blind surface itself. Therefore, the subject can immediately detect the shift by slightly changing the fixation of the eyes.

Another advantage of the invention is that gray values can be displayed in images in fine steps, for example 256 gray value steps on a typical television screen.

Therefore, it is possible to perform threshold measurement in a very simple manner.

In a particularly advantageous embodiment of the invention, the examining person, for example the doctor, is provided with a second screen, so that the examining person is always aware of the location and size of the respective defect area.

Regarding the present method, it has been found to be particularly advantageous to artificially increase the intraocular pressure of the subject in order to detect glaucoma early. This can be done, for example, by means of a suction pump or drug treatment. In this way, visual disturbances that may occur due to natural changes in intraocular pressure can be predictively diagnosed.

Another advantage arises from being aware of i-c.

That is, interested patients can control their scotoma from their home television screen. To do this, the patient must always be at the same distance from the screen (
It must be noted that approximately 30 crIL) must be maintained, one eye covered, and the fixation stabilized by the fixation point. In this way, if the absolute scotoma enlarges or a new scotoma develops, the observant patient will be able to detect this on their home television.

Example Next, the present invention will be explained based on an example using figures.

In FIG. 1, a side view of the video monitor IQ is shown. A chin support member 3 is used to accurately determine the distance from the subject's eyes 2 to the subject's eyes 2 using a predetermined measurement method, and the screen of the video monitor 1 4 to the chin support member 3 is such that the field of view to be examined has a full diameter of 60 mm.

A front view of the screen 4 is shown. A fixation point 5 is shown in FIG. 2, and the fixation point 5 is usually a screen 4.
Located in the center of However, the fixation point 5 can be shifted laterally and in the height direction, so that the viewing area can be shifted towards the edges and thus enlarged. Shifting the viewpoint 5 means that the dimensions of the video monitor 1 are
It is completely unnecessary if the dog is sharp enough to display the entire field of view of the subject.

In practice, we have found that scotomas are most clearly visible when provided with a high flicker frequency, high contrast, and a noisy area with small particles. For this reason, many medical examinations use bright elements with a frequency of 50 Hz and a brightness of 60 cd/77!2 m, and 0-8 c
d/m2 (7) The dark element Q is applied to the brightness. The ratio of dark elements to bright elements is preferably 50 or 70 parts for dark elements. These elements are small squares measuring 15 angles.

In the apparatus shown in FIG. 1, the patient's head has a distance of approximately 30 crrL from the monitor. The test area of the monitor has dimensions of 4, for example 25X, 38 cIrL, so the field of view is about 65 degrees horizontally and about 24 degrees vertically. With the device of the invention it is possible to insert polar coordinates with a circular shape with a viewing angle interval of 5° into the monitor.

The present invention allows not only noise areas and polar coordinates to appear in the test area, but also to represent a uniform area in the traditional perimetry. This area can be provided with various brightnesses between 60 and 0.8 cd/-m2.

Next, the diagnosis method of the present invention will be explained based on FIGS. 3a, 3b, and 3c. The examination begins with the display of colors on all monitors in the noise area (Figure 3a). After the subject's eyes have been fixed on the fixation point shown in the center of the screen, the patient can very quickly indicate the scotoma area to the doctor. Once the scotoma region is indicated, the clinician can insert it into the noise area, for example by means of a mouse, as shown in FIG. 3a. Polar coordinates are then displayed on the screen, and a scotoma appears inserted into the polar coordinates, as shown in FIG. 3b. This area can then be further examined in a uniform background by static or dynamic perimetry. In dynamic perimetry, the doctor can freely move the test point on the monitor, for example with a mouse (FIG. 3C), and at the same time display the visual field defect by pressing the full key. This method is illustrated in the lower half of the screen in Figure 3C.

The perimetry is performed automatically by the method of Lascou perimetry, in which the test points are randomly distributed in a preselected area, as shown in the upper half of Figure 3C. be done. The subject counts the pixels seen at that time by pressing a button.

The method of the invention provides an excellent screening method by which only the pathological area within the visual field can then be examined on the same monitor by means of quantitatively measured perimetry. In this way, the examination time is significantly reduced compared to all previous methods.

Another advantage is that the method is simple and easy to implement. It is possible for the doctor and patient to sit adjacent to each other and look together at a monitor screen on which the noise area, polar coordinates, and perimetry area appear sequentially or in any order. With this method, visual field examination is no longer a painful test, and there is no need for patients to feel stressed.

In FIG. 4, 1 is shown an apparatus for forming a video image suitable for threshold perimetry from a video signal of a microcomputer.

field For video images suitable for threshold perimetry.

It has been found that only two graduated gray values are required for the background and the test points, and a fixation (gaze) symbol that can be freely selected to be either black or white. With the additional electronic equipment of the microcontroller and computer, images suitable for threshold visual field measurement can be easily obtained from the four TTs.
It can be formed from an L-video signal. The prerequisite for this method to be possible is that the microcomputer supplies a digital video signal consisting of more than 3 bits. The video signal makes it possible to: 1. create another black and white image, for example on a second viewing monitor;

Both gray values, which are formed in fine stages, are digital values (
The data bus is B bi depending on the number of gray steps required.
t or more bits are transmitted from the microcomputer and stored in the electronic controller (latch). Additionally, the microcomputer transmits TTL signals via the four TTL outputs of its video processor. The first TT of these four TTL signals
The L signal (A) switches the multiplexers, each of which switches one of the electronic registers.
One digital to analog converter (D/A converter)
Connect to. It is therefore possible to form a video image in which the gray values fluctuate very strongly from a binary image sent out by a microcomputer and taken from a corresponding video output supply.

The second TTL signal (B) switches the multiplexer into three-states, so that the pull-up resistor connected to the input of the D/A converter supplies the maximum digital word to this converter. This second TTL signal (
B) allows inserting a fixed symbol whose gray value corresponds to the maximum digital input value of the D/A converter.

Corresponding a fixed symbol to the smallest digital value is the third T.
This third signal is possible due to the TL signal (C).
Control the inverting pin l-5 present in the D/A converter.

In this way, it is possible to represent all fixation (fixation) symbols corresponding to the smallest digital value.

The D/A converter supplies an analog signal into which the required video synchronization pulses can be mixed by means of an analog switch.

These pulses are also sent out as a fourth TTL signal from the video processor of the host computer.

[Brief explanation of the drawing]

1 is a side view schematically illustrating one embodiment of the device according to the invention; FIG. 2 is a sectional view taken along the section line ■-■ in FIG. 1; FIGS. 3a and 3b; FIG. 3C is a diagram illustrating the actual method in the medical examination, and FIG. 4 is a block circuit diagram of a device for forming a video image for threshold perimetry. 1.--Video monitor, 2.--Subject's eyes, 3.--
- Chin support member, 4...screen, 5...fixation point. Figure 2

Claims (1)

Claims: 1. A search device for a scotoma in a subject's eye, comprising a screen forming an image, wherein the image comprises a number of closely adjacent black and white, or 1. A search device for a scotoma in an eye of a subject, comprising color pixels, wherein the pixels vary in brightness at a high frequency. 2. The device for searching for a scotoma in the eye of a subject according to claim 1, wherein the pixels are uniformly distributed in the shape of a noise pattern. 3. The image is a fixed point for the patient's eye to be examined (5
) The device for searching for a scotoma in the eye of a subject according to claim 1 or 2. 4. In the eye of a subject according to claim 3, characterized in that the fixation point can be shifted both horizontally and vertically on the screen in order to examine the central and peripheral areas. Scotoma search device. 5. The scotoma in the subject's eye according to any one of claims 1 to 4, characterized in that the size of the pixel can be changed in the noise pattern. Search device. 6. Claims 1 to 4 characterized in that the image can have larger pixels in relation to the visual acuity of the subject.
The device for searching for a scotoma in the eye of a subject according to any one of the above. 7. The device for searching for a scotoma in the eye of a subject according to any one of claims 1 to 6, wherein the image has high contrast. 8. The subject according to any one of claims 1 to 7, characterized in that it is possible to perform brightness compensation of the image using a photosensor in order to accurately measure differences in photosensitivity for each retinal location. A device to search for scotomas in the examiner's eyes. 9. The device for searching for a scotoma in an eye of a subject according to any one of claims 1 to 8, wherein the image has pixels only on a predetermined plane. 10. The device for searching for a scotoma in an eye of a subject according to any one of claims 1 to 9, wherein the pixel distribution and/or brightness can be controlled by a random function or a program. 11. The apparatus for searching for a scotoma in the subject's eye according to claim 10, characterized in that it is possible to change the frequency of alternating luminance changes of the pixels. 12. The device for searching for a scotoma in an eye of a subject according to any one of claims 1 to 11, wherein the pixels are formed of various colors or alternating colors. 13. According to any one of claims 3 to 12, the position and shape of the fixation point (5) relative to the subject's eye can be adjusted to the scotoma surface of the subject's eye. A search device for scotomas in the eyes of subjects. 14. The device for searching for a scotoma in the eye of a subject according to any one of claims 1 to 13, wherein the second image for control is provided by the examiner. 15. A method for searching for a scotoma in the eye of a subject, which is used in the device for searching for a scotoma in the eye of a subject according to any one of claims 1 to 14, comprising: An image consisting of a number of pixels located closely adjacent to each other and having a fixation point for the eye, located at a predetermined distance from each other and with continuous alternating brightness, is displayed on the screen. A scotoma in the eye of a subject, for example, for use in the apparatus for searching for a scotoma in the eye of a subject according to any one of claims 1 to 14. Search method. 16. The method for searching for a scotoma in a subject's eye according to claim 15, wherein the brightness and brightness fluctuation of each pixel are adjustable. 17. The method of searching for a scotoma in the eye of a subject according to claim 15 or 16, wherein the luminance fluctuation is performed periodically. 18. The subject according to any one of claims 15 to 17, wherein the subject is provided with a reproducible noise pattern that is larger in dark areas than in bright areas. How to search for scotoma in eyes. 19. Dark test points on a light background, or bright test points on a dark background, or colored test points are additionally formed on the screen and shifted, as the case may be, for static or dynamic perimetry. The method for searching for a scotoma in an eye of a subject according to any one of claims 15 to 18. 20. When using a flat screen, the size of the inspection point and/or
20. The method of searching for a scotoma in the eye of a subject according to claim 19, characterized in that the luminance can be adapted depending on the position on the image screen. 21. The method of searching for a scotoma in the eye of a subject according to any one of claims 15 to 18, characterized in that the noise image is projected onto a sphere. 22. Claims 15 to 2, characterized in that the values determined on the screen are stored and optionally printed.
1. The method of searching for a scotoma in the eye of a subject according to any one of Items 1 to 1. 23. The method for searching for a scotoma in the eye of a subject according to any one of claims 15 to 22, characterized in that a schematic diagram of the visual field in which the power is displayed is inserted on the screen. . 24. The subject according to any one of claims 15 to 23, wherein the method for searching for a scotoma in the subject's eye is performed by artificially increasing the intraocular pressure of the subject. How to search for a scotoma in the examiner's eye. 25. The coordinate network of examination points on the monitor is displayed in a scaled and aligned manner in each case depending on a variable distance from the eye to be examined to the monitor. 24. The method for searching for a scotoma in the eye of a subject according to any one of Items 24 to 24. 26. Any one of claims 15 to 25, characterized in that the patient's eyes are detected by a camera, and the position of the eyes is displayed on the control monitor, preferably by inserting a linear cross. The method for searching for a scotoma in the eye of a subject as described in item 1. 27. Any one of claims 15 to 26, characterized in that the brightness variations are statistical and are displayed on a structured or unstructured background of one or more colors. A method for searching for a scotoma in the eye of a subject described in . 28. A method for forming a video signal suitable for threshold perimetry from a microcomputer video signal, in which the video image has two gray values adjustable in fine steps and the ability to freely select either black or white. the video image is formed by four TTL video signals of the microcomputer, the microcomputer supplies a video signal with a bit number of more than 3 bits, and both gray values are digitally and electronically A first TTL output of the video processor is stored in a register (latch) and supplies a TTL signal (A) which switches a multiplexer, said multiplexer each time converting one of said electronic registers into a digital/ connected to an analog converter (D/A converter), and the second TTL output side of the video processor is TTL
The TTL signal (B) switches the multiplexer into three-state, and therefore the pull-up resistor connected to the input side of the D/A converter sets the maximum digital value to the A third TTL signal is applied to a D/A converter, and in turn inserts a gaze symbol with a gray value corresponding to the maximum digital input value of said D/A converter, and for adjusting said gaze symbol by a minimum digital value. (C), said third TTL signal (C) controls an inversion bit of said D/A converter, said D/A converter provides an analog signal, and said third TTL signal (C) controls an analog switch for said analog signal. A method for forming a video image suitable for threshold perimetry, characterized in that video synchronization pulses are mixed through the video processor of the host computer, and these combined pulses are sent out as a fourth TTL signal from the video processor of the host computer.