JP2007061416A - Visual field testing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To minutely specify a lesion section while utilizing an advantage of a visual field test where Frequency doubling illusion is applied. <P>SOLUTION: A visual field testing apparatus is provided with an optotype presentation means for presenting a check optotype of a prescribed size for testing a visual field failure by applying Frequency doubling illusion. The apparatus divides a prescribed visual field range into a plurality of divisions by a prescribed size of the optotype, presents the optotype by changing a division of presenting the optotype of the prescribed size one by one and changing the contrast of the optotype. Based on the viewing response of a subject in the case, the apparatus obtains a sensitivity threshold of the contrast to test the visual field failure of the eye to be tested. The apparatus is provided with a control means which deviates and presents the optotype of the prescribed size so as to contain a part of the division when there exists a division where the sensitivity threshold obtained in the divided division is smaller than a prescribed reference value, and which obtains the sensitivity threshold based on the viewing response of the subject in the case of changing and presenting the contrast of the optotype at a presenting position. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a visual field inspection apparatus for inspecting visual field disorders due to glaucoma of an eye to be examined.

It is known that retinal ganglion cells are damaged early in glaucoma. A visual field inspection device called Frequency doubling Technology (FDT) applying Frequency doubling illusion (frequency overlap illusion phenomenon), which is a function of the M cell system, is known as a device for inspecting retinal ganglion cell damage (for example, Non-patent document 1). In inspection using frequency doubling illusion, contrast sensitivity is measured by shaking a low spatial frequency sinusoidal fringe at a high temporal frequency. In the FDT visual field inspection device, the range of the central visual field of 20 ° is divided into 16 sections of 4 × 4 sections divided by 10 °, and a circular section with a central radius of 5 ° is added to a total of 17 locations to obtain a viewing angle. Sections presenting a 10 ° × 10 ° sine wave grid stripe target are sequentially changed, and the contrast of the target is changed and presented, and a visual response of the subject is obtained to obtain a contrast sensitivity threshold. .
Yoshida Toda and three others, "Glaucoma by Frequency doubling Technology", New Ophthalmology, Medical Sakai Publishing, December 30, 1999, Vol. 16, No. 12, p1723-1726

  However, while the FDT visual field inspection apparatus can inspect visual field disturbances of retinal neurons with high sensitivity in a relatively short time, the size of the checkered target is as large as 10 ° × 10 °. I could only identify it.

  It is a technical object of the present invention to provide a visual field inspection apparatus capable of finely identifying a diseased part while taking advantage of visual field inspection applying frequency doubling illusion.

  In order to solve the above problems, the present invention is characterized by having the following configuration.

(1) Applying frequency doubling illusion, comprising target display means for presenting a checkered target of a predetermined size for inspecting visual field disturbance, and dividing a predetermined field of view into a plurality of sections with the predetermined size of the target Then, the visual field of the eye to be examined is obtained by sequentially changing the sections presenting the target of the predetermined size and obtaining a contrast sensitivity threshold based on the visual response of the subject when the contrast of the target is changed. In the visual field inspection apparatus for inspecting an obstacle, when there is a section where the sensitivity threshold obtained in the divided section is lower than a predetermined reference value, the target of the predetermined size is included so as to include a part of the section. Control means is provided for obtaining a sensitivity threshold based on the visual response of the subject when the presentation is performed while the contrast of the target is changed at the presentation position.
(2) The control means of (1) shifts the target of the predetermined size so that each of the upper left, lower left, upper right, and lower right quarters of the section whose sensitivity threshold is lower than the predetermined reference value is included. Or present the target of the predetermined size so as to include the upper half, the lower half, the right half, and the left half of the section where the sensitivity threshold is lower than the predetermined reference value, or In combination, the predetermined size target is shifted and presented.
(3) The control means according to (1) or (2), wherein when the sensitivity threshold obtained by shifting the target of the predetermined size is lower than the reference value, the part of the target of the predetermined size further overlapped The target of the predetermined size is displayed while being shifted, and the contrast is changed at the presenting position to obtain a sensitivity threshold value.
(4) The control means according to (1) or (2) uses the sensitivity obtained when the predetermined size target is overlapped as an initial value of contrast when the target is shifted and presented. It is determined based on a threshold value.

  ADVANTAGE OF THE INVENTION According to this invention, a disease site | part can be specified finely, utilizing the advantage of the visual field inspection which applied Frequency doubling illusion. In addition, the examination can be performed without prolonging the examination time when specifying the diseased part.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of a visual field inspection apparatus according to the present invention.

  A liquid crystal display 2 (visual target presenting means) for presenting a test target is arranged in the housing of the apparatus main body 1, and a forehead pad 4 for placing the eye to be examined at a distance of about 30 cm from the display 2 is formed. . The subject fixes the forehead with the forehead pad 4 and looks into the display 2 in the housing. A shutter 6 that switches the left and right of the eye to be inspected is disposed in the window portion through which the subject looks into the housing. A display 8 for displaying inspection results and an input unit 10 having various switches are arranged outside the housing of the apparatus main body 1. The display 2, the shutter 6, the display 8, and the input unit 10 are connected to the control unit 20. The control unit 20 is connected to a response switch 12 operated by the subject. The control unit 20 has a visual field inspection program, controls display on the display 2 in accordance with the inspection program, obtains a response signal from the response switch 12, advances the visual field inspection program, and calculates an inspection result.

  Next, prior to the description of the operation of visual field inspection, visual field inspection using frequency doubling illusion will be described with reference to FIGS. In visual field inspection using frequency doubling illusion, a black and white sine wave checkered pattern (see FIG. 2 (a)) having a low spatial frequency (for example, 0.25 Hz) and a sine wave checkered pattern opposite in phase (see FIG. 2 (b)). ) Are alternately presented at a high time frequency (for example, 25 Hz / second). In other words, the black and white striped pattern is alternately inverted every predetermined time. When the black and white stripe pattern is inverted every predetermined time, as shown in FIG. 2 (c), a lattice fringe target M in which the number of lattice fringes appears to be double the actual number is presented. When there is an abnormality in the visual field of the eye to be examined, the number of checkered stripes does not appear twice as much as that in the abnormal part, and it cannot be recognized as a checkered pattern and appears uniform. Therefore, the checkered pattern M is sequentially presented at different locations, and the contrast of the checkered pattern M is changed at the same point of presentation to obtain a contrast threshold that can be recognized by the eye to be examined. Can be identified. Note that when changing the contrast of the grid pattern M, only the contrast is changed without changing the spatial frequency and the average brightness.

  Next, the presentation position of the checkered target M presented on the display 2 will be described. The presenting position of the lattice fringe target M is controlled so as to be different in the course of the inspection. In the first inspection step, as shown in FIG. 3A, the visual field range of 20 ° in the center is divided by a checkered target M having a rectangular area size of 10 ° × 10 ° (vertical × horizontal). Presented in 16 × 4 sections 101-116. In addition, in order to measure the sensitivity of the fovea, a lattice fringe target M is also presented in the central section 120 of a circular region having a central radius of 5 °. Since the fixation point K is always displayed at the center of the field of view, the eye to be examined always has this fixation point K fixed. Conventionally, the check of the contrast sensitivity of each section has been performed by presenting the lattice fringe target M in a total of 17 positions of the sections 101 to 116 and the center section 120, but the present invention further includes an inspection step described below. Introduce and make it possible to specify the abnormal part in detail.

  By the way, the checkered pattern target M in the inspection applying the frequency doubling illusion is compared with the type in which the bright spot is projected on the dome-shaped screen, such as the viewing angle 10 ° × 10 °, due to the characteristics of the target. It is necessary to present with a large target size. That is, if the size of the checkered target M is made too small, the checkered pattern becomes difficult to see, and inspection using the frequency doubling illusion becomes impossible. In the above inspection step, the target M is presented in a predetermined section divided for each size of the target M, so that the diseased part can be specified only for each large-sized section. Therefore, based on the inspection result of each section obtained in the previous inspection step, when there is a section whose contrast sensitivity threshold is lower than a predetermined standard, the viewing angle is 10 ° × 10 ° so as to include a part of the section. The target M having a size is displayed while being shifted, and the contrast sensitivity threshold is measured. As a result, it is possible to more precisely identify a portion suspected of having a disease.

  An example of the inspection program of this apparatus will be described. The examiner first inputs the age of the subject through the input unit 10. The age of the subject is used as a deviation probability from the normal value by age. When the start program of the input unit 10 is pressed to execute the inspection program, the left eye is shielded by the shutter 6 in order to start the inspection from the right eye. The subject's eye is caused to fixate the central fixation point K, and when the subject can recognize the examination target M, the response switch 12 is pressed.

  In the first inspection step, as shown in FIG. 3A, the checkered pattern M is set for a predetermined time (for example, 0.3) in the 16 rectangular area sections 101 to 116 and the central circular area section 120. Second) and the presentation position of the visual target M is sequentially changed at random. In addition, the contrast sensitivity of the target M at each position is changed between 56 dB and 0 dB (the lowest contrast is 56 dB and the highest contrast is 0 dB). The contrast of the initial value is presented, for example, at 30 dB near the intermediate value.

  In this examination, if there is a response signal from the response switch 12 that the subject can be seen, the contrast is lowered by 4 dB (closer to 56 dB). Thereafter, if there is a response that the subject can be seen at the same presentation position, the contrast is lowered by 4 dB each time. If there is no response from the subject, the contrast is increased by 1 dB with reference to when it is seen, and the value when it is finally visible is determined as the threshold value.

  On the other hand, if there is no response of the subject due to the presentation of the initial value of contrast, the contrast is increased by 4 dB (closer to 0 dB). Thereafter, if there is no response from the subject at the same presentation position, the contrast is increased by 4 dB each time. If there is a response from the subject, the contrast is lowered by 1 dB from the contrast value, and the value when it is finally visually recognized is determined as the threshold value.

  In this inspection step, for example, when the threshold value of the section 108 is lower than a predetermined reference value (for example, 20 dB) (when the contrast sensitivity of the retina is poor and the threshold value is 0 dB side from 20 dB), FIG. ) To (d), the position 201a including the upper left quarter part of the section 108, the position 201b including the lower left quarter part of the section 108, and the upper right quarter part of the section 108 are included. The target M having a size of 10 ° × 10 ° is displayed in a shifted manner at the position 201 c and the position 201 d including the lower right quarter portion of the section 108. By the display control of the display 2, the target presentation position can be arbitrarily changed in dot units. If it cannot be displayed at a position outside the predetermined section, such as position 201c or position 201d, due to restrictions on the display screen of display 2, it is combined with the upper left 1/4 and lower left 1/4 parts and shifted by the upper half. It is good also as a position shifted only by the position and the lower half.

  Note that the reference value (20 dB in the above example) for determining whether or not to present the target M in a shifted manner in order to specify the diseased site in detail is based on the age-specific normal value stored in the control unit 20 in advance. Is determined according to the age of the subject input through the input unit 10.

  Here, the initial value of the contrast when the target M is presented at each of the positions 201a, 201b, 201c, and 201d is not the same value (30 dB) as the inspection steps of the sections 101 to 116, but the target M is If the determination is made based on the threshold value obtained in the overlapping sections, the inspection time can be shortened. For example, start with a threshold for the compartment 108 that requires detailed inspection. Or it is good also as an average value of the threshold of the division on which the target M is piled up. That is, for the position 201a, the average value of the threshold values of the sections 103, 104, 107, and 108 on which the target M is superimposed is used. If there is no response from the subject at the start from such an initial value, the contrast is increased by 2 dB. After that, it is raised by 2 dB until there is a response that it is seen, and when it is seen, it is lowered by 1 dB. If there is a response to the initial value, the response is lowered by 2 dB. Thereafter, the response is lowered by 2 dB until there is no response. When there is no response, it is increased by 1 dB. By starting from such an initial value, the inspection time when the target M is shifted and presented is shortened, and the entire inspection time can be prolonged.

  When the contrast is changed, the visual target M is randomly presented at other positions so that the target M is not presented at the positions 201a to 201d. In this case, the position where the threshold has already been determined may be used.

  FIG. 5 is a diagram illustrating a display example of a result of inspection performed by shifting the visual target M to the positions 201a to 201d including a part of the section 108 as described above. The inspection result is displayed on the display 8. It is also possible to print from a printer (not shown). In FIG. 5, each numerical value indicates an example of the sensitivity threshold in the sections 101 to 117 and the sensitivity threshold in the positions 201 a to 201 d obtained by shifting the target M. Since the area portion where the target M is presented in the section 108 and the position 201a is lower than the reference value (20 dB), it is hatched so as to be visually distinguished from the others. From the overlap of the hatched portion and the numerical value of the threshold value, it can be seen that there is a diseased part in the upper left quarter part of the section 108, and can be specified more finely than the conventional method of specifying the diseased part for each section.

  When there is a position that is below the reference value (20 dB) with respect to the threshold value obtained by the presentation of the target M at the positions 201a to 201d, the target is further viewed centering on the portion where the target M is superimposed on the section 108. The mark M may be shifted and inspected. For example, when the threshold value obtained at the presentation position of the position 201a is lower than the reference value of 20 dB, as shown in FIG. 6, the upper left quarter portion 202 of the section 108 that is an overlapping portion of the section 108 and the position 201a is set. The target M is shifted and presented at the centered position. At this position, the contrast is changed in the same manner as described above, and the threshold value of the sensitivity is inspected. Thereby, a threshold value centered on the upper left quarter portion 202 is further obtained. If the threshold value of this portion is added to the corresponding location of the test result in FIG. 5 (the center position of the upper left quarter portion of the section 108) and displayed, it becomes easier to understand the extent of the diseased portion.

  In the embodiment described above, the visual field range of the center 20 ° is divided into 16 4 × 4 sections with the size of the checkered target M (10 ° × 10 °), but the screen of the display 2 is displayed. If it can be enlarged, the target M may be presented by dividing the range of the center 30 ° into 25 5 × 5 locations.

  Further, when there is a section whose threshold value is lower than the predetermined reference value, the method of shifting the target M including a part of the section is not limited to the method of FIG. For example, as shown in FIG. 7, for the section 108 whose threshold value is lower than a predetermined reference value, the method of presenting the target M in a shifted manner so as to include the upper half, the lower half, the right half, and the left half may be used. . Alternatively, a method in which the methods of FIGS. 4 and 7 are combined may be used. These also make it possible to further specify the disease site.

  Still further, in the inspection step in which the target M is shifted and presented including a part of the predetermined section (101 to 116), the threshold value is lower than the predetermined reference value even if the threshold value is not obtained in all the sections. It may be introduced at the stage when the compartment is obtained. In this way, it is possible to efficiently perform an inspection performed by randomly changing the presentation position of the target M.

It is a schematic block diagram of a visual field inspection apparatus. It is a figure explaining the sine wave lattice fringe of the visual field inspection which applied Frequency doubling illusion. It is a figure explaining the presentation position of the checkered eye chart shown on a display. It is a figure which shows the example which shifts and shows a checkered target. It is a figure of the example of a display of a test result. It is a figure which shows the other example which shifts and presents a checkered target. It is a figure which shows the other example which shifts and presents a checkered target.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Apparatus main body 2 Display 6 Shutter 8 Display 10 Input part 12 Response switch 20 Control unit M Sinusoidal lattice fringe target

Claims (4)

Applying frequency doubling illusion to provide a visual target presenting means for presenting a checkered visual target of a predetermined size for inspecting visual field disturbances, dividing a predetermined visual field range into a plurality of sections with the predetermined size of the visual target, Inspect the visual field disturbance of the eye by obtaining the contrast sensitivity threshold based on the visual response of the subject when changing the sections that present the target of a predetermined size in order and changing the contrast of the target. In the visual field inspection apparatus, when there is a section where the sensitivity threshold obtained in the divided section is lower than a predetermined reference value, the target of the predetermined size is presented so as to include a part of the section. And a visual field inspection apparatus comprising a control means for obtaining a sensitivity threshold based on a visual response of the subject when the contrast of the visual target is changed at the presentation position. Whether the control means of claim 1 presents the target of the predetermined size in a shifted manner so that each of the upper left, lower left, upper right, and lower right quarters of the section whose sensitivity threshold is lower than the predetermined reference value is included. Or by shifting the target of the predetermined size so as to include the upper half, the lower half, the right half and the left half of the section whose sensitivity threshold is lower than the predetermined reference value, respectively, or combining these A visual field inspection apparatus, wherein the visual target having a predetermined size is shifted and presented. The control means according to claim 1 or 2, wherein when a sensitivity threshold obtained by shifting the target of the predetermined size is lower than the reference value, the control unit further centers on a portion where the target of the predetermined size is overlapped. A visual field inspection apparatus characterized in that a size target is shifted and presented, and a sensitivity threshold is obtained by changing contrast at the presentation position. The control means according to claim 1 or 2, wherein an initial value of contrast when the target having the predetermined size is shifted and presented is determined based on a sensitivity threshold obtained in a section where the target of the predetermined size is overlaid. A visual field inspection apparatus characterized by:

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