JP5048284B2 - Ophthalmic equipment - Google Patents

Description

  The present invention relates to an ophthalmologic apparatus that determines the progress of glaucoma based on static visual field inspection data of a visibility threshold.

In order to diagnose glaucoma in the subject's eye, a target is fixedly presented at a specific point in the field of view of the subject's eye, and a target is presented at another point. There is known a static perimeter that calculates the brightness discrimination threshold (visibility threshold) (see, for example, Patent Document 1). In addition, as a representative method for determining the degree of progression (stage classification) of glaucoma, the Aulthorn classification Greve modified method (hereinafter abbreviated as AG method) based on static visual field inspection data is known (for example, Non-patent document 1).
JP-T 6-54804 Katsuaki Kitazawa, glaucomatous visual field change, glaucoma clinic revised 3rd edition, Kanehara Publishing, P98-105, 1996

  However, the conventional determination of the degree of progression of glaucoma has been performed by the examiner observing the visual field data. Therefore, the determination requires skill, and there are problems of determination accuracy and determination variation.

  In view of the problems of the prior art, an object of the present invention is to provide an ophthalmologic apparatus capable of determining the degree of progression of glaucoma.

In order to solve the above problems, the present invention is characterized by having the following configuration.
(1) Data input means for inputting visual field inspection data of the visibility distribution of the subject's eye obtained by a static perimeter, and optic nerve fiber strike data for the visual field range from which visual field inspection data was obtained are stored In order to interpolate an unmeasured point located between adjacent measurement points in the luminous intensity distribution obtained by the storage means and the static perimeter, the position is close to the unmeasured point in the vertical and horizontal directions. Interpolation processing means for calculating the data at the unmeasured points by performing averaging processing based on the measurement results of the measurement points to be performed, and interpolation processing of the visibility distribution, and the interpolation processing obtained by the interpolation processing means Determining means for determining the degree of progression of glaucoma based on the visibility distribution of the later visual field inspection data and the strike data of the optic nerve fiber.

  According to the present invention, the degree of progression of glaucoma can be automatically determined.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing an ophthalmologic apparatus used in this embodiment. The ophthalmologic apparatus is a perimeter 100 that acquires static visual field data of a subject's eye, and a visual field data analysis apparatus that performs analysis processing for determining the degree of progression of glaucoma based on the visual field data obtained by the perimeter 100 300. Although the ophthalmologic apparatus of this embodiment is configured to include the perimeter 100, the perimeter 100 may not be included as long as it has a function of inputting visual field data. The perimeter 100 used in the present embodiment presents bright spots having different sizes, brightness, and the like to the subject's eyes at various positions, and obtains the visibility threshold of the subject's eye according to the response to the bright points. It is a static perimeter to measure (inspect).

  A hemispherical dome-shaped screen 1 is arranged in front of the subject's eyes, and a stimulus target is presented from the target projection unit 2 on this screen 1. The target projection unit 2 includes a light source 3, a projection lens 4, a movable mirror 5, and an aperture 6 with a variable aperture diameter. An illumination unit 7 uniformly illuminates the screen 1 and forms background light at the time of inspection. The movable mirror 5 is driven by a driving mechanism (not shown) and changes the position of a spot target (stimulus target) projected on the screen 1 by the light source 3 and the projection lens 4. The movable mirror 5 can be composed of two sets of galvanometer mirrors. By changing the aperture diameter of the aperture 6, the size of the spot target projected on the screen 1 can be changed. A fixation target 10 is provided at the center of the screen 1. The target projection unit 2 is connected to the control unit 30. The control unit 30 drives and controls the movable mirror 5 of the target projection unit 2, and is projected onto the screen 1 to change the position of the stimulus target. Further, the light amount of the light source 3 is adjusted, and the luminance of the stimulus target (presentation target) projected on the screen 1 is changed. Connected to the control unit 30 are a monitor 21, a keyboard 22 serving as an input device, a mouse 23, a response switch 15 for the subject to respond to the stimulus target, and the like. The control unit 30 controls the light source 3, the mirror 5, the aperture 6, the illumination unit 7, etc. (control of background luminance), the display control of the monitor 21, and the like, and performs arithmetic processing on the acquired visual field data of the subject's eye A control unit 31, a glaucoma progression degree determination processing program, a memory 32 that stores a template of optic nerve fiber strike (described later), and the like, and a data input unit 33 that inputs a fundus image. The memory 32 also stores the acquired visual field data and fundus image. The monitor 21, control unit 30, keyboard 22, mouse 23, etc. used in this embodiment are general computers.

  A procedure for acquiring visual field data of the subject's eye with the perimeter 100 will be described. When the measurement of the visual field is started, the screen 1 is illuminated by the illumination unit 7 with a predetermined luminance. The subject is provided with the response switch 15 to fixate the fixation target 10. Then, the target projection unit 2 presents the stimulus target with a predetermined luminance on the screen 1 based on the stimulus target presentation position stored in the memory 32 and the command of the control unit 31. The subject presses the response switch 15 when the presented target is visible. The luminance and measurement point (presentation position) of the visual target are changed using the keyboard 22 and the mouse 23, and a visibility threshold value at which the subject can be visually recognized is obtained at each measurement point (measurement point). The obtained measurement results at each measurement point are stored in the memory 32 in association with the measurement point. By repeating this operation, the visibility threshold value at each measurement point is plotted, and the visual field data of the subject's eye is acquired. The visual field data acquired in this way is stored in the memory 32 together with the subject information (left and right eye information, age, sex, ID number, etc.) acquired in advance.

  The visual field data acquired by the perimeter 100 is shown in FIG. FIG. 2 schematically shows visual field data 200 (static visual field) of the subject's eye displayed on the monitor 21. The center (intersection) of the coordinates is the fixation center, and corresponds to the visual axis of the subject's eye, that is, the fovea. The numerical value (measured value) shown on the coordinates is the visibility (light sensitivity) at the time of the response of the subject's eye, and indicates the visibility threshold. In this visual field data 200, the visibility threshold is expressed in decibels (dB). The positions of these measured values indicate the position of the visual target presented to the subject's eye by the perimeter 100 described above, and serve as measurement points on the visual field. At this time, the positions of the measurement points are located at predetermined intervals in the up, down, left, and right directions, here at intervals of 5 degrees. The measurement range is a radius of 30 ° (60 ° in total) around the fovea. Further, in such visual field data, a measurement point with an extremely low visibility threshold located at a predetermined distance in the horizontal axis direction from the center of coordinates (intersection of the vertical axis and horizontal axis) Corresponds to the position of the blind spot (optic nerve head). In the visual field data 200 shown in FIG. 2, it is estimated that the optic nerve head is located in the vicinity of a visibility of 0 dB on the right side from the center of the coordinates.

  The field-of-view data 200 has a measurement point interval of 5 degrees, and is preferably finer in order to determine the progress of glaucoma based on the visibility distribution. However, if the measurement points are set at fine intervals in the static visual field inspection, the inspection time becomes long and a burden is imposed on the subject. For this reason, it is preferable to use data obtained by averaging the positions and numerical values of adjacent measurement points in the visual field data 200 and interpolating the entire visual field data 200. An example of an interpolation method for the visual field data 200 will be described below.

  FIG. 7 is an enlarged view of part of the visual field data 200. As shown in the figure, the measurement points in FIG. 7A have an interval of 5 ° in the vertical and horizontal directions. A in the figure is a point where the measurement was not actually performed, and the numerical value (visibility threshold) of this point A is calculated (estimated) using a nearby measurement point. FIG. 7 (b) shows a result of averaging the measurement points and calculating a numerical value at intervals of 1 degree. Here, the interval between adjacent measurement points is divided into five, and averaged by increasing or decreasing stepwise. A numerical value enclosed by a square in the figure is a value calculated by an average calculation.

  The value of point A is calculated from the averaged value. In consideration of the numerical value of the point A in the vertical and horizontal directions and the interval (angle) to each numerical value, the control unit 31 performs an averaging operation using the following calculation formula (Formula 1).

点Ａの上方向にある数値２７、下方向にある数値２６は、点Ａに対しそれぞれ２度、３度の間隔を持っている。この２度、３度を重みとして、５分の３と５分の２をかけてものを足している。点Ａの左方向にある数値３２、右方向にある数値２３は、点Ａに対しそれぞれ３度、２度の間隔を持っている。この場合も先程と同様にそれぞれ、５分の２と５分の３の重みをつけたものを足している。点Ａの上下方向、左右方向の重みをつけた数値はそれぞれの方向での平均を示しており、上下方向、左右方向を足して２で割ることにより、点Ａでの上下左右方向での平均値が算出される。このような演算を制御部３１が繰り返すことにより、５度間隔の視野データ２００に対して１度間隔で視感度データを持つ補間演算された視野データが得られる。

The numerical value 27 in the upward direction of the point A and the numerical value 26 in the downward direction have an interval of 2 degrees and 3 degrees with respect to the point A, respectively. These 2 degrees and 3 degrees are weighted and multiplied by 3/5 and 2/5. The numerical value 32 on the left side of the point A and the numerical value 23 on the right side have an interval of 3 degrees and 2 degrees with respect to the point A, respectively. In this case as well, the weights of 2/5 and 3/5 are added as before. The numerical values with weights in the vertical and horizontal directions of point A indicate the average in each direction. By adding the vertical and horizontal directions and dividing by 2, the average in the vertical and horizontal directions at point A is shown. A value is calculated. By repeating such calculation, the control unit 31 obtains field-of-view data subjected to interpolation calculation having visibility data at intervals of 1 degree with respect to the field-of-view data 200 at intervals of 5 degrees.

  Next, the optic nerve fiber strike template used for determining the progress of glaucoma will be described. Visual field disorders such as isolated dark spots and arcuate dark spots in glaucoma are considered to be caused by disorders of the optic nerve fibers of the retina, and their progression spreads along the direction of the optic nerve fibers. For this reason, the progress of glaucoma can be determined by examining how the visual sensitivity changes along the optic nerve fiber.

  FIG. 3A shows an example of a template in which the strike data of the optic nerve fiber is schematically shown. The template 50 is a schematic representation of the strike of the optic nerve fiber N including the optic nerve head H and the fovea F in a normal healthy person. The template 50 indicating the strike direction of the optic nerve fiber N is set as data in a larger range than the visual field data. Nerve fibers N extend radially from the nipple H. In addition, since the nerve fibers N are concentrated around the fovea F, the state where the nerve fibers N are concentrated from the fovea F is depicted. The nerve fibers N, the nipple H, and the fovea F of the template 50 as described above are managed as coordinate data and stored in the memory 32. N1 is one of the nerve fibers N and is a certain nerve fiber.

  A method for matching (superimposing) the optic nerve fiber strike template 50 to the visual field data 200 will be described. First, a method of using the fundus image of the subject's eye will be described. FIG. 3B shows a fundus image 60 obtained by photographing the fundus of the subject's eye. The fundus image 60 is a visible image or an infrared image taken by a fundus camera, a scanning microscope, or the like (not shown). Electronic data of the fundus image 60 obtained by a fundus camera or the like is input by the input unit 33 and stored in the memory 32. In the fundus image 60, 61 is an optic disc and is distinguished from the retina 64. 62 indicates the position of the fovea, which is not shown in detail, but is slightly darker than the surrounding retina 64. Reference numeral 63 denotes a blood vessel extending in all directions from the optic disc 61. Although illustration is omitted, fine small blood vessels branch from the blood vessel 63.

  By superimposing such a fundus image 60 on the size of the template 50, for example, by adjusting the distance between the nipple H and the fovea H to the distance between the nipple 61 and the fovea 62, the pattern is schematically displayed. The shape, position, and the like of the optic nerve fiber of the template 50 shown in FIG. 6 approach the shape and position of the optic nerve fiber of the actual fundus of the subject's eye.

  Next, a procedure for adjusting the size of the template 50 and superimposing it on the fundus image 60 will be briefly described. Position information of the nipple 61 and the fovea 62 is acquired from the fundus image 60. As described above, the nipple 61 can easily grasp the border on the image with respect to the surrounding retina 64. Further, the feature on the image of the fovea 62 can be easily extracted from the surrounding retina 64. Using these characteristics and a well-known image processing technique, position information (center position information) of the nipple 61 and the fovea 62 is acquired as coordinates. Further, the distance between the nipple 61 and the fovea 62 is acquired. On the other hand, the template 50 is managed by coordinates as described above, and the enlargement / reduction of the template 50 can be easily achieved by a known technique. A series of these processes is performed by the control unit 31, and the processing results are stored in the memory 32.

  The nipple H and the fovea F of the template 50 are located at the same position on the nipple 61 and the fovea 62 of the fundus image 60 obtained as described above (the distance between the nipple 61 and the fovea 62 and the nipple H And the template 50 showing the strike of the nerve fiber relatively close to the fundus of the subject's eye is obtained. The template 51 is superimposed on the fundus image 60 (see FIG. 4). At this time, the control unit 31 also performs superimposition (superimposition) processing. By superimposing the field-of-view data 200 on this template 51, it becomes easy to take correspondence between the position of the measured value and the position of the nerve fiber.

  When the template 50 is superimposed on the fundus image 60 displayed on the monitor 21, the template 50 is displayed on the fundus image 60 from a menu (not shown) displayed on the monitor 21 by operating the keyboard 22 or the cursor 40. Select the item to overlay. When a signal instructing superposition of the templates 50 is sent to the control unit 31, the control unit 31 calls the template shown in FIG. Next, the control unit 31 determines from the subject information stored in the memory 32 in advance whether the fundus image 60 shown in FIG. 3B is the left or right eye data, and based on the result, the template 50 display directions (for the left eye and for the right eye) are determined in advance.

  Next, the control unit 31 superimposes the template 51 (or the template 50) and the fundus image 60 by the method described above, and causes the monitor 21 to display a screen as shown in FIG. In this way, the control unit 31 performs a series of matching. Note that the template 51 may be prepared for the left eye and the right eye, and various templates corresponding to the age and the like are prepared, and based on the subject data corresponding to the acquired visual field data. A preferred template may be selected from the prepared templates. In addition, the configuration may be such that the operator can adjust the enlargement / reduction of the template 50 described above with the cursor 40 while looking at the fundus image 60.

  In the above description, the size of the template 50 is changed and superimposed on the fundus image 60. However, the present invention is not limited to this. The distance between the nipple 61 and the fovea 62 on the fundus image 60 is calculated without displaying the figure where the fundus image 60 and the template 51 overlap on the monitor 21, and the distance between the nipple H and the fovea F of the template 50 is matched. It may be a process.

  The superposition of the visual field data 200 and the template 51 (or template 50) will be described. If the fundus image 60 and the template 51 can be superimposed, the viewing angle with respect to the fovea F is determined based on the shooting angle of view of the fundus image 60 (which is known by a shooting optical system such as a fundus camera). The position data of the optic nerve fiber of the template 51 can be acquired. Then, by aligning the fovea F of the template 51 with the center point 201 of the visual field data 200 and matching the visual field angle of the visual field data 200 with the visual field angle of the template 51, as shown in FIG. Template 51 can be superimposed. The center point 201 of the field-of-view data 200 and the fovea F of the template 51 are corresponding points of both data, and can be used as a reference for superposition. Thus, by using the template 51 adjusted using the fundus image 60 of the subject's eye, the optic nerve fiber can be driven according to the individual difference of the subject's eye.

  Although it is preferable to use the template 51 adjusted using the fundus image 60 as described above, a method of matching the template 50 with the visual field data 200 without using the fundus image 60 may be used. Also in this case, both data can be superimposed by matching the fovea F of the template 50 with the center point 201 of the visual field data 200 and matching the visual field angle of the visual field data 200 with the visual field angle of the template 50. At this time, the optic nerve fiber strike data of the template 50 is prepared at an average viewing angle of the human eye. The superimposition of both data is processed by the control unit 31.

  As shown in FIG. 5A, the optic nerve fiber N corresponding to the measured value of the visual field data 200 can be schematically grasped. Here, paying attention to the nerve fiber N1, a method for obtaining the visibility data on the nerve fiber N1 will be described. First, a corresponding measurement point is extracted for one nerve fiber. Since a plurality of measurement points are collected by one nerve fiber, this is called grouping. Here, the measurement point of the visual field data 200 is made to correspond to the focused nerve fiber N1. There are several measurement points of the visual field data 200 on or near the nerve fiber N1. A measurement point (visibility threshold having position information) on the line of the nerve fiber N1 is a group of nerve fibers N1. Further, among several measurement points in the vicinity of the nerve fiber N1, the closest measurement point in the vertical and horizontal directions is defined as a group of nerve fibers N1. At this time, a neighborhood range is set in advance. For example, the range is within 5 ° in the vertical direction.

  When grouping is performed based on such a procedure, a group (set) shown in FIG. The measurement points considered to be on the nerve fiber N1 are 0, 29, 25, 31, 26, 23, 29, 30, 24, 28 in order from the nipple H. This is group G1. Such grouping is performed on each nerve fiber. The measurement points classified for each nerve fiber are determined.

  The control unit 31 performs the series of processes described above. Since the position information of the nerve fibers N and N1 and the field-of-view data 200 of the template 51 are managed by coordinates, grouping is easily performed by the procedure described above. The closest measurement point in the vicinity of the nerve fiber N1 is set as the measurement point on the nerve fiber N1, and is added to the group G1. The control unit 31 stores the information of the group G1 for the nerve fiber N1 in the memory 32. The same processing is performed for other nerve fibers.

  As described above, the visibility data on the nerve fiber N1 may be obtained using the distribution of the visibility data finely interpolated.

  Next, a method for determining the degree of progression of glaucoma based on the distribution of visibility data based on the AG method will be described. FIG. 6 is a diagram schematically showing the progress of glaucoma by the AG method classified into each stage (Stage). The following are examples of criteria for each stage based on the AG method.

Stage 1: 0-10 dB area is smaller than nipple area, or 0 dB area on one nerve fiber is less than 20% Stage 2: 0 dB area on one nerve fiber is more than 20% and less than 50% Stage 3: More than 50% and less than 90% of 0 dB area on one nerve fiber Stage 4: More than 90% of 0 dB area on one nerve fiber Stage 5: Full field of view with 0 dB area more than 1 quadrant 25-50% of
Stage 6: 0 dB region is circular (0 dB of nerve fibers continuous on the upper and lower sides is 90% or more)
In the determination of stage 1 described above, the nipple area uses a predetermined value based on the average size of the human eye. Moreover, although it is preferable to obtain | require the area | region of 0-10 dB from the distribution of the visibility data interpolated at fine intervals, such as 1 degree, it is also possible to determine using the value of a measurement point directly.

  In the determination of stages 1 to 4, the 0 dB region on the nerve fiber is obtained from the visibility data grouped for each nerve fiber. Since the progression of glaucoma spreads along the direction of the optic nerve fiber, each stage can be accurately and accurately determined by examining the ratio of the dark spot (0 dB) on the nerve fiber. In the determination of the stage 5 and the stage 6, the 0 dB visibility distribution region is obtained from the visual field data. The stage 5 is determined on the basis of the expansion of the 0 dB region in the four quadrants divided by the horizontal axis and the vertical axis around the center point 201 in the visual field data 200 of the visibility distribution.

  The result determined by the control unit 31 in accordance with the above determination criteria is displayed on the monitor 21. In addition, the numerical value used for said determination standard is only an illustration, and is not limited to this. For example, in stages 2 to 6, an area having 0 dB as a dark spot is used for determination, but 0 to 10 dB may be determined as a dark spot.

It is a figure which shows the perimeter 100 and the visual field data analysis apparatus 300 which are the ophthalmologic apparatuses of this embodiment. It is a figure which shows the visual field data 200 acquired by the perimeter 100. FIG. It is a figure which shows the fundus image 60 which image | photographed the template 50 which modeled the strike data of the optic nerve fiber, and the fundus of the subject's eye. FIG. 6 is a diagram in which a fundus image 60 is superimposed on a template 51. FIG. 5 is a diagram in which visual field data 200 is superimposed and displayed on a template 51. It is the figure which showed typically what classified the progress degree of the glaucoma by AG method into each stage (Stage). It is a figure explaining the interpolation of the visual field data.

Explanation of symbols

2 Target Projection Unit 7 Illumination Unit 21 Monitor 30 Control Unit 31 Control Unit 32 Memory 33 Data Input Unit 40 Mouse Cursor 50, 51 Template 60 Fundus Image 100 Perimeter 200 Field Data 201 Center Point 300 Field Data Analysis Device N, N1 Nerve Fiber F, 62 Fovea H, 61 Optic nerve head G1 group

Claims (1)

Data input means for inputting visual field inspection data of the visibility distribution of the subject's eye obtained by a static perimeter, and storage means for storing optic nerve fiber strike data for the visual field range from which visual field inspection data was obtained In order to interpolate an unmeasured point located between adjacent measurement points in the visibility distribution obtained by the static perimeter, the measurement point located near the unmeasured point in the vertical and horizontal directions An interpolation processing unit that calculates data at the unmeasured point by performing an averaging process based on the measurement result of the above and performs an interpolation process of the visibility distribution, and the interpolated process obtained by the interpolation processing unit An ophthalmologic apparatus comprising: determination means for determining a degree of progression of glaucoma based on a visual sensitivity distribution of visual field inspection data and a strike data of the optic nerve fiber.

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