Visual field inspection device, control method for visual field inspection device, and visual field inspection program
阅读说明：本技术 视野检查装置、视野检查装置的控制方法以及视野检查程序 (Visual field inspection device, control method for visual field inspection device, and visual field inspection program ) 是由 井上智 木村伸司 山中健三 于 2019-03-06 设计创作，主要内容包括：本发明提供一种能够缩短视野检查所需的时间并且得到精确的检查值的视野检查装置、视野检查装置的控制方法以及视野检查程序。视野检查装置具有：第一概率密度函数获取部,其进行工序(1),在工序(1)中,得到与通过第一次的视野检查得到的结果值x1相对应的概率密度函数f(x1)；刺激阈值决定部,其进行工序(2),在工序(2)中,根据x1的范围来设定刺激阈值t1以将概率密度函数f(x1)的概率密度分开；检查结果获取部,其进行工序(3),在工序(3)中,得到在第一次的视野检查中是否得到t1以上的结果的检查结果；第二概率密度函数获取部,其进行工序(4),在工序(4)中,得到从概率密度函数f(x1)减少t1以上或者小于t1的概率密度而形成的概率密度函数f(x2)；以及判定部,其进行工序(5),在工序(5)中,判定是否成为概率密度函数f(x2)的标准偏差σ收敛于小于规定值的状态。(The invention provides a visual field inspection device, a control method of the visual field inspection device and a visual field inspection program, which can shorten the time required by the visual field inspection and obtain accurate inspection values. The visual field inspection device comprises: a first probability density function acquisition unit that performs step (1) and that, in step (1), acquires a probability density function f (x1) corresponding to a result value x1 obtained by a first visual field inspection; a stimulus threshold determination unit that performs a step (2) in which, in the step (2), a stimulus threshold t1 is set so as to divide the probability density of the probability density function f (x1) according to the range of x 1; an inspection result acquisition unit that performs step (3) and in step (3), acquires an inspection result of whether or not a result of t1 or more was obtained in the first visual field inspection; a second probability density function obtaining unit that performs step (4) and obtains a probability density function f (x2) obtained by reducing the probability density of t1 or more or less than t1 from the probability density function f (x1) in step (4); and a determination unit that performs step (5), and in step (5), determines whether or not the standard deviation σ of the probability density function f (x2) has converged to a state smaller than a predetermined value.)
1. A visual field inspection device is provided with:
a first probability density function acquisition unit that performs a step (1) of obtaining a probability density function f (x1) corresponding to a result value x1 obtained by a first visual field examination, the probability density function f (x1) being a probability density function under the condition of using at least two of the number of years elapsed since the previous examination, the age, examination coordinates, the presence or absence of a past medical history, the name of a patient, the stage of a disease, an estimation threshold value used in a past visual field examination, and an index indicating the reliability of a result of a past visual field examination, for a subject;
a stimulus threshold determination unit that performs a step (2) in which a stimulus threshold t1 is set in accordance with a range x1 of a probability density function f (x 1);
an inspection result acquisition unit that performs a step (3) of obtaining an inspection result of whether or not a result of t1 or more is obtained in a first visual field inspection in the step (3);
A second probability density function obtaining unit that performs a step (4) of obtaining a probability density function f (x2) in which a probability density smaller than t1 is reduced from the probability density function f (x1) when an inspection result of t1 or more is obtained in the step (4), and obtaining a probability density function f (x2) in which a probability density of t1 or more is reduced from the probability density function f (x1) when a result of t1 or more is not obtained in the step (4); and
a determination unit that performs a step (5) of determining whether or not the standard deviation σ of the probability density function f (x2) has converged to a state smaller than a predetermined value in the step (5),
wherein, when the determination unit determines that the standard deviation σ has converged to a state smaller than the predetermined value, the value of x2 having the highest probability density in the probability density function f (x2) is regarded as the check value to terminate the check,
when the determination unit determines that the standard deviation σ has not converged to a state smaller than the predetermined value, the stimulus threshold value determination unit, the inspection result acquisition unit, the second probability density function acquisition unit, and the determination unit replace the first time with the second time, replace x2 with x3, replace x1 with x2, replace the stimulus threshold value t1 with t2, and replace the second probability density function acquisition step with the third probability density function acquisition step, and the steps (2), (3), (4), and (5) are sequentially repeated until it is determined that the standard deviation σ of the probability density function f (x3) formed by reducing the probability density according to the inspection result has converged.
2. The visual field inspection device according to claim 1,
the inspection result acquiring unit is a perimeter.
3. The visual field inspection device according to claim 1 or 2,
in the second probability density function acquisition section, the probability density is reduced by multiplying the probability density function f (x1) by the response function.
4. The visual field inspection device according to any one of claims 1 to 3,
the predetermined value at which the standard deviation σ converges in the determination unit is a value in a range of 1.0dB to 3.5 dB.
5. A method for controlling a visual field inspection apparatus, the method comprising:
a first probability density function acquisition unit that performs a first probability density function acquisition step (1) of acquiring a probability density function f (x1) corresponding to a result value x1 obtained by a first visual field examination, the probability density function f (x1) being a probability density function under a condition that at least two of an elapsed number of years from a previous examination, an age, examination coordinates, a presence or absence of an existing medical history, a medical name, a disease stage, an estimation threshold used in a past visual field examination, and an index indicating reliability of a result of a past visual field examination are adopted for a subject;
A stimulation threshold determination unit that performs a stimulation threshold determination step (2) in which a stimulation threshold t1 is set according to the range x1 of the probability density function f (x 1);
an inspection result acquisition unit performing an inspection result acquisition step (3) of acquiring an inspection result indicating whether or not a result of t1 or more is obtained in a first visual field inspection in the inspection result acquisition step (3);
a second probability density function acquisition unit that performs a second probability density function acquisition step (4) of obtaining a probability density function f (x2) in which a probability density smaller than t1 is reduced from the probability density function f (x1) when an inspection result of t1 or more is obtained, and obtaining a probability density function f (x2) in which a probability density of t1 or more is reduced from the probability density function f (x1) when a result of t1 or more is not obtained in the second probability density function acquisition step (4); and
the determination unit performs a determination step (5) for determining whether or not the standard deviation sigma of the probability density function f (x2) is in a state of being smaller than a predetermined value,
in the method for controlling a visual field inspection apparatus, the visual field inspection apparatus is controlled such that:
When it is determined in the determination step (5) that the standard deviation σ has converged to a state smaller than the predetermined value, the value x2 having the highest probability density in the probability density function f (x2) is regarded as the inspection value to terminate the inspection,
when it is determined in the determination step (5) that the standard deviation sigma has not converged to a state smaller than a predetermined value, in the stimulation threshold value determining step (2), the inspection result acquiring step (3), the second probability density function acquiring step (4), and the determining step (5), replacing the first time with the second time, replacing x2 with x3, replacing x1 with x2, replacing the stimulation threshold t1 with t2, and replacing the second probability density function acquisition step with the third probability density function acquisition step, the stimulation threshold determination step (2), the test result acquisition step (3), the second probability density function acquisition step (4), and the determination step (5) are sequentially repeated until it is determined that the standard deviation σ of the probability density function f (x3) formed by reducing the probability density according to the test result has converged to a state smaller than a predetermined value.
6. The visual field inspection apparatus control method according to claim 5,
The number of times the stimulus threshold value determination step (2), the inspection result acquisition step (3), the second probability density function acquisition step (4), and the determination step (5) are performed is three or less.
7. The control method of the visual field inspection apparatus according to claim 5 or 6,
in the second probability density function obtaining step (4), the probability density is reduced by multiplying the probability density function f (x1) by the response function.
8. The visual field inspection apparatus control method according to any one of claims 5 to 7,
in the determination step (5), the predetermined value at which the standard deviation σ converges is a value in a range of 1.0dB to 3.5 dB.
9. A visual field inspection program causes a computer device to function as:
a first probability density function acquisition unit that performs a step (1) of obtaining a probability density function f (x1) corresponding to a result value x1 obtained by a first visual field examination, the probability density function f (x1) being a probability density function under the condition of using at least two of the number of years elapsed since the previous examination, the age, examination coordinates, the presence or absence of a past medical history, the name of a patient, the stage of a disease, an estimation threshold value used in a past visual field examination, and an index indicating the reliability of a result of a past visual field examination, for a subject;
A stimulus threshold determination unit that performs a step (2) in which a stimulus threshold t1 is set in accordance with a range x1 of a probability density function f (x 1);
an inspection result acquisition unit that performs a step (3) of obtaining an inspection result of whether or not a result of t1 or more is obtained in a first visual field inspection in the step (3);
a second probability density function obtaining unit that performs a step (4) of obtaining a probability density function f (x2) in which a probability density smaller than t1 is reduced from the probability density function f (x1) when an inspection result of t1 or more is obtained in the step (4), and obtaining a probability density function f (x2) in which a probability density of t1 or more is reduced from the probability density function f (x1) when a result of t1 or more is not obtained in the step (4); and
a determination unit that performs a step (5) of determining whether or not the standard deviation σ of the probability density function f (x2) has converged to a state smaller than a predetermined value in the step (5),
in the course of the visual field inspection procedure,
when the judgment unit judges that the standard deviation sigma has converged to a state smaller than the predetermined value, the value of x2 having the highest probability density in the probability density function f (x2) is regarded as the check value to terminate the check,
When the determination unit determines that the standard deviation σ has not converged to a state smaller than the predetermined value, the stimulus threshold value determination unit, the inspection result acquisition unit, the second probability density function acquisition unit, and the determination unit replace the first time with the second time, replace x2 with x3, replace x1 with x2, replace the stimulus threshold value t1 with t2, and replace the second probability density function acquisition step with the third probability density function acquisition step, and the steps (2), (3), (4), and (5) are sequentially repeated until it is determined that the standard deviation σ of the probability density function f (x3) formed by reducing the probability density according to the inspection result has converged to a state smaller than the predetermined value.
10. The visual field inspection program of claim 9, wherein,
the number of times the steps (2), (3), (4) and (5) are performed is three or less.
11. The visual field inspection program according to claim 9 or 10,
in the step (4), the probability density is reduced by multiplying the probability density function f (x1) by the response function.
12. The visual field inspection program according to any one of claims 9 to 11,
In the step (5), the predetermined value at which the standard deviation σ converges is a value in a range of 1.0dB to 3.5 dB.
Technical Field
The present invention relates to a visual field inspection device, a control method of the visual field inspection device, and a visual field inspection program.
Background
The following techniques are known (patent document 1 [ claim 1 ]): when a different type of visual field inspection is performed from the previous visual field inspection during the visual field inspection, the initial brightness of the index in the corresponding visual field coordinate of the visual field inspection to be performed later is calculated based on the sensitivity distribution data of the previous visual field inspection, and is determined as the brightness equal to or close to the sensitivity indicated in the sensitivity distribution data.
Disclosure of Invention
Problems to be solved by the invention
The problem of the content described in
Therefore, an object of the present invention is to provide a visual field inspection device, a control method for the visual field inspection device, and a visual field inspection program, which can shorten the time required for visual field inspection and obtain an accurate inspection value.
Means for solving the problems
Regardless of the screening test or the threshold test described in
The present inventors have conceived the following method: the brightness of the optotype in the first and subsequent visual field examinations is determined based on data (hereinafter, also referred to as "big data") accumulated by the visual field examinations performed on persons other than the subject to be examined.
That is, a method of determining the examination condition of the subject based on the big data is conceivable. Further, the following methods are contemplated: an end condition for converging the examination is determined based on the big data and a result value obtained by the first visual field examination actually performed.
The present invention is completed based on the above knowledge in the following manner.
A first aspect is a visual field inspection apparatus including:
a first probability density function acquisition unit that performs a step (1) of obtaining a probability density function f (x1) corresponding to a result value x1 obtained by a first visual field examination, the probability density function f (x1) being a probability density function under the condition of using at least two of the number of years elapsed since the previous examination, the age, examination coordinates, the presence or absence of a past medical history, the name of a patient, the stage of a disease, an estimation threshold value used in a past visual field examination, and an index indicating the reliability of a result of a past visual field examination, for a subject;
A stimulus threshold determination unit that performs a step (2) in which a stimulus threshold t1 is set in accordance with a range x1 of a probability density function f (x 1);
an inspection result acquisition unit that performs a step (3) of obtaining an inspection result of whether or not a result of t1 or more is obtained in a first visual field inspection in the step (3);
a second probability density function obtaining unit that performs a step (4) of obtaining a probability density function f (x2) in which a probability density smaller than t1 is reduced from the probability density function f (x1) when an inspection result of t1 or more is obtained in the step (4), and obtaining a probability density function f (x2) in which a probability density of t1 or more is reduced from the probability density function f (x1) when a result of t1 or more is not obtained in the step (4); and
a determination unit that performs a step (5) of determining whether or not the standard deviation σ of the probability density function f (x2) has converged to a state smaller than a predetermined value in the step (5),
wherein, when the determination unit determines that the standard deviation σ has converged to a state smaller than the predetermined value, the value of x2 having the highest probability density in the probability density function f (x2) is regarded as the check value to terminate the check,
When the determination unit determines that the standard deviation σ has not converged to a state smaller than the predetermined value, the stimulus threshold value determination unit, the inspection result acquisition unit, the second probability density function acquisition unit, and the determination unit replace the first time with the second time, replace x2 with x3, replace x1 with x2, replace the stimulus threshold value t1 with t2, and replace the second probability density function acquisition step with the third probability density function acquisition step, and the steps (2), (3), (4), and (5) are sequentially repeated until it is determined that the standard deviation σ of the probability density function f (x3) formed by reducing the probability density according to the inspection result has converged.
According to the aspect described in the first aspect, the second aspect,
the inspection result acquiring unit is a perimeter.
According to the aspect described in the first or second aspect, the third aspect is,
in the second probability density function acquisition section, the probability density is reduced by multiplying the probability density function f (x1) by the response function.
According to a fourth aspect of any one of the first to third aspects, the fourth aspect is,
The predetermined value at which the standard deviation σ converges in the determination unit is a value in a range of 1.0dB to 3.5 dB.
A fifth aspect is a method for controlling a visual field inspection apparatus, including the steps of:
a first probability density function acquisition step (1) of acquiring a probability density function f (x1) corresponding to a result value x1 obtained by a first visual field examination, the probability density function f (x1) being a probability density function under the condition of using at least two of an elapsed number of years from a previous examination, an age, examination coordinates, a past medical history, a medical name, a disease stage, an estimation threshold value used in a past visual field examination, and an index indicating reliability of a result of a past visual field examination, for a subject;
a stimulation threshold determination step (2) for setting a stimulation threshold t1 in accordance with the range x1 of the probability density function f (x 1);
an inspection result acquisition step (3) for acquiring an inspection result indicating whether or not a result of t1 or more is obtained in the first visual field inspection;
a second probability density function obtaining step (4) of obtaining a probability density function f (x2) in which a probability density smaller than t1 is reduced from the probability density function f (x1) when an inspection result of t1 or more is obtained, and obtaining a probability density function f (x2) in which a probability density of t1 or more is reduced from the probability density function f (x1) when a result of t1 or more is not obtained; and
A determination step (5) for determining whether or not the standard deviation sigma of the probability density function f (x2) is in a state of being smaller than a predetermined value,
wherein the control method of the visual field inspection device controls the visual field inspection device such that:
when it is determined in the determination step (5) that the standard deviation σ has converged to a state smaller than the predetermined value, the value x2 having the highest probability density in the probability density function f (x2) is regarded as the inspection value to terminate the inspection,
when it is determined in the determination step (5) that the standard deviation sigma has not converged to a state smaller than a predetermined value, in the stimulation threshold value determining step (2), the inspection result acquiring step (3), the second probability density function acquiring step (4), and the determining step (5), replacing the first time with the second time, replacing x2 with x3, replacing x1 with x2, replacing the stimulation threshold t1 with t2, and replacing the second probability density function acquisition step with the third probability density function acquisition step, the stimulation threshold determination step (2), the test result acquisition step (3), the second probability density function acquisition step (4), and the determination step (5) are sequentially repeated until it is determined that the standard deviation σ of the probability density function f (x3) formed by reducing the probability density according to the test result has converged to a state smaller than a predetermined value.
According to a sixth aspect of the present invention, in the fifth aspect,
the number of times the stimulus threshold value determination step (2), the inspection result acquisition step (3), the second probability density function acquisition step (4), and the determination step (5) are performed is three or less.
According to the fifth or sixth aspect, in the seventh aspect,
in the second probability density function obtaining step (4), the probability density is reduced by multiplying the probability density function f (x1) by the response function.
According to an eighth aspect of the present invention, as set forth in any one of the fifth to seventh aspects,
in the determination step (5), the predetermined value at which the standard deviation σ converges is a value in a range of 1.0dB to 3.5 dB.
A ninth aspect is a visual field inspection program for causing a computer device to function as:
a first probability density function acquisition unit that performs a step (1) of obtaining a probability density function f (x1) corresponding to a result value x1 obtained by a first visual field examination, the probability density function f (x1) being a probability density function under the condition of using at least two of the number of years elapsed since the previous examination, the age, examination coordinates, the presence or absence of a past medical history, the name of a patient, the stage of a disease, an estimation threshold value used in a past visual field examination, and an index indicating the reliability of a result of a past visual field examination, for a subject;
A stimulus threshold determination unit that performs a step (2) in which a stimulus threshold t1 is set in accordance with a range x1 of a probability density function f (x 1);
an inspection result acquisition unit that performs a step (3) of obtaining an inspection result of whether or not a result of t1 or more is obtained in a first visual field inspection in the step (3);
a second probability density function obtaining unit that performs a step (4) of obtaining a probability density function f (x2) in which a probability density smaller than t1 is reduced from the probability density function f (x1) when an inspection result of t1 or more is obtained in the step (4), and obtaining a probability density function f (x2) in which a probability density of t1 or more is reduced from the probability density function f (x1) when a result of t1 or more is not obtained in the step (4); and
a determination unit that performs a step (5) of determining whether or not the standard deviation σ of the probability density function f (x2) has converged to a state smaller than a predetermined value in the step (5),
in the course of the visual field inspection procedure,
when the judgment unit judges that the standard deviation sigma has converged to a state smaller than the predetermined value, the value of x2 having the highest probability density in the probability density function f (x2) is regarded as the check value to terminate the check,
When the determination unit determines that the standard deviation σ has not converged to a state smaller than the predetermined value, the stimulus threshold value determination unit, the inspection result acquisition unit, the second probability density function acquisition unit, and the determination unit replace the first time with the second time, replace x2 with x3, replace x1 with x2, replace the stimulus threshold value t1 with t2, and replace the second probability density function acquisition step with the third probability density function acquisition step, and the steps (2), (3), (4), and (5) are sequentially repeated until it is determined that the standard deviation σ of the probability density function f (x3) formed by reducing the probability density according to the inspection result has converged to a state smaller than the predetermined value.
According to a tenth aspect of the present invention, in the ninth aspect,
the number of times the steps (2), (3), (4) and (5) are performed is three or less.
According to the ninth or tenth aspect, in the eleventh aspect,
in the step (4), the probability density is reduced by multiplying the probability density function f (x1) by the response function.
According to an aspect of any one of the ninth to eleventh aspects, the twelfth aspect is,
In the step (5), the predetermined value at which the standard deviation σ converges is a value in a range of 1.0dB to 3.5 dB.
ADVANTAGEOUS EFFECTS OF INVENTION
According to the present invention, it is possible to provide a visual field inspection device, a control method of the visual field inspection device, and a visual field inspection program, which can shorten the time required for visual field inspection and obtain an accurate inspection value.
Drawings
Fig. 1 is a flowchart showing steps (a control method of the visual field inspection apparatus) performed by each unit in the visual field inspection apparatus according to the present embodiment.
Fig. 2 (a) shows that "age:
Fig. 3 (a) shows that "age:
Fig. 4 (a) shows that "age:
Fig. 5 (a) shows that "age:
Fig. 6 is a graph showing a response function used after the first visual field inspection in example 1.
Fig. 7 (a) shows that "age:
Fig. 8 (a) shows that "age:
Detailed Description
Embodiments of the present invention will be described in detail below with reference to the drawings.
In the present embodiment, the following procedure is explained. Further, "-" indicates a value equal to or higher than a predetermined value and equal to or lower than a predetermined value.
1. Visual field inspection device
1-1. first probability density function acquisition section
1-2 stimulation threshold determination part
1-3 inspection result acquisition part
1-4. second probability density function obtaining part
1-5. determination section
2. Control method of visual field inspection device
3. Visual field inspection program
4. Effects of the embodiments
5. Modifications and the like
In addition, a known visual field inspection apparatus can be used for a configuration not described below. For example, the structure described in japanese patent No. 5826902, which is filed by the present applicant, and the structure described in japanese patent laid-open publication No. 2017-192564, which is also filed by the present applicant, can be suitably employed. The visual field inspection device may be a device in which an HMD (head mounted display) type device and a control computer unit are connected, or may be a device of a stationary type.
Fig. 1 is a flowchart showing steps (a control method of the visual field inspection apparatus) performed by each unit in the visual field inspection apparatus according to the present embodiment. Next, description will be made with reference to fig. 1.
<1. Vision field inspection apparatus >
1-1. first probability density function acquisition section
The first probability density function acquisition step (1) is performed by a first probability density function acquisition unit. In this step, a probability density function f (x1) corresponding to the result value x1 obtained by the first visual field inspection is obtained. The probability density function f (x1) is obtained under the condition that at least two of the following items are employed.
The number of years elapsed since the previous examination for the subject
Age
Checking coordinates
Existence or non-existence of past medical history
Name of disease
Stage of disease
Estimated threshold in the inspection of the past field of view
An index indicating the reliability of the previous visual field inspection result
The "number of years elapsed since the previous examination" for the subject is the number of years after the visual field examination is performed, as the name thereof. "age" is also as its name implies.
The "inspection coordinates" refer to inspection points used in the screening inspection and the threshold inspection described in
The "presence or absence of a past medical history" is, as the name implies, for example, whether glaucoma is currently suffering (or has been suffering) or not. The "disease name" is, as its name implies, glaucoma, for example. The "presence or absence of a past history" and the "disease name" may be collectively referred to as the "presence or absence of a past history of glaucoma". "disease stage" refers, for example, to the degree of progression of glaucoma.
The "estimation threshold used in the visual field inspection in the past" is as follows.
In the conventional visual field inspection, one inspection value is obtained at the end of one inspection. However, the test value is only an estimated value, and is a value that largely reflects the state of the subject, but is not necessarily a value that completely reflects the state of the subject. In this regard, the same applies to the inspection value finally obtained in the present embodiment.
Therefore, in the present specification, not only one inspection value obtained at the end of inspection using the visual field device of the present embodiment (and the value of x used in the determination of the predetermined value as the standard deviation σ in the determination step (5), which will be described in detail later) but also one inspection value obtained at the end of conventional visual field inspection is referred to as an estimation threshold.
When the items of the estimation threshold value used in the visual field inspection in the past are used, the probability density function is obtained as follows.
For example, assume a case of a sample having a optotype of 21dB identified and an optotype of 27dB identified in the next visual field examination. The number of samples is 27dB on the horizontal axis of a probability density function (for example, a graph having a form as shown in FIG. 2 (a)) when the past estimation threshold is 21 dB. By accumulating the number of samples in this manner, a probability density function in the case where the estimation threshold value used in the visual field inspection in the past was 21dB was obtained.
In this specification, a larger value of the inspection value (dB) in the visual field inspection indicates that the subject can recognize even a dark target (i.e., a better state in terms of the visual field), and a smaller value indicates that the subject cannot recognize even a bright target (i.e., a worse state in terms of the visual field).
"index indicating the reliability of the results of the previous visual field inspection" is a reliability index described in japanese patent application laid-open No. 2017-192564 applied by the present applicant. In the present specification, the reliability index is an index indicating the level of reliability, and is a result based on the number of answers that are not likely to exist in general under a condition that the value deviates greatly from the inspection result.
Japanese patent application laid-open No. 2017-192564 describes a reliability target. The description of the reliability index in jp 2017-192564 a is entirely described in the present specification.
Next, the large data will be explained. The big data used in the present embodiment is data obtained by accumulating data on each subject input to each visual field inspection apparatus. The big data may be obtained from a server at another location through a communication line. However, instead of the big data, representative data may be prepared, or representative data may be prepared for each item in the stage before the data is accumulated.
In this step, a specific example using big data is described. When the subject starts the visual field examination, "age:
In this way, the data corresponding to "age:
Fig. 2 (a) shows that "age:
Fig. 2 (b) shows that "age: age 70 "," exam coordinates: -27, -3 "in the case of a probability density function f (x 1).
The items other than the above are similarly data that match the combination condition of the selected two or more items, extracted from the large data accumulated by the visual field inspection in each area. Then, based on the extracted data, data on a visual target of which brightness can be confirmed is counted among results of visual field inspection performed on each subject satisfying the selected condition. Then, a first probability density function is created with the horizontal axis as a threshold (dB) and the vertical axis as a frequency, and the first probability density function is acquired.
Fig. 3 (a) shows that "age:
Fig. 3 (b) shows that "age:
Fig. 4 (a) shows that "age:
Fig. 4 (b) shows that "age:
It is reasonable to set the horizontal axis of the graph not as the estimation threshold but as only the "threshold". The reason is as follows.
In the present embodiment, there is a "stimulation threshold value" that is different from the estimated threshold value that is finally obtained as the test value. The "stimulus threshold value" is a luminance adopted as a visual target for visual field inspection when an inspection result acquisition step (3) described later, that is, a step of acquiring a result of visual field inspection, is performed.
As will be described in detail later, in the stimulus threshold value determination step (2), the stimulus threshold value t1, which is the luminance of the optotype used in the inspection result acquisition step (3), is set in accordance with the range of x1 of the probability density function f (x 1). Therefore, the threshold on the horizontal axis of the graphs of fig. 2 (a) and (b) is a value that can be the
On the other hand, the abscissa of the graph of the probability density function f (x2) obtained in the second probability density function acquisition step (4) described later may be the estimation threshold or the stimulus threshold.
When it is determined in the determination step (5) that the inspection is ended with the standard deviation σ smaller than the predetermined value, x2 having the highest probability density becomes the estimation threshold value which is the inspection value finally obtained. Conversely, when the standard deviation σ is equal to or greater than the predetermined value, the stimulation threshold determination step (2) is performed again based on the probability density function f (x 2). In this case, the horizontal axis of the graph of the probability density function f (x2) is the stimulation threshold.
That is, the horizontal axis of the graph of the probability density function f (x2) is the estimation threshold or the stimulation threshold, and is therefore simply referred to as the "threshold" as a result of the determination step (5). Further, it is not excluded to adopt a stimulation threshold value used in the visual field examination in the past as a term of the first probability density function acquisition step (1).
The above is the contents performed in this step, and is the function realized by the first probability density function acquiring unit.
1-2 stimulation threshold determination part
The stimulus threshold determination step (2) is performed by the stimulus threshold determination unit. Through this process, the stimulation threshold t1 is set according to the range of x1 of the probability density function f (x 1).
The "range of x1 of the probability density function f (x 1)" means a range of x1 from a minimum value to a maximum value of the probability density. In fig. 2 (a), the range corresponds to 0dB to 34 dB. As this range shows, there may be x1 with a probability density of zero in the middle of the range.
According to this configuration, in the second probability density function obtaining step (4) described later, the probability density of the stimulus threshold t1 or more or less than t1, which is the unnecessary probability density, can be reduced. As a result, the time required for the visual field inspection can be shortened.
The result value x1 in the range of 10% to 90% (preferably 30% to 70%, more preferably 35% to 65%, and still more preferably 40% to 60%) of the cumulative probability density may be set as the
Note that t1 may be set randomly while satisfying the above conditions, or t1 (details will be described later) may be set by the arithmetic unit so that the number of visual field inspections is the minimum.
1-3 inspection result acquisition part
The inspection result acquisition step (3) is performed by the inspection result acquisition unit. In this step, an inspection result is obtained as to whether or not a result of t1 or more is obtained in the first visual field inspection.
As a specific content of this step, a visual target with luminance t1(dB) is presented to the subject, and an inspection result is obtained as to whether or not the subject can recognize the visual target.
The inspection result acquiring unit includes a perimeter. In addition, as a structure other than the perimeter, the following structure is cited: the perimeter is arranged at a remote place in advance, and the inspection result acquisition unit of the perimeter inspection apparatus in the present embodiment acquires the inspection result obtained by the perimeter.
1-4. second probability density function obtaining part
The second probability density function obtaining step (4) is performed by a second probability density function obtaining unit. When the inspection result of t1 or more is obtained by this step, the probability density function f (x2) is obtained by reducing the probability density smaller than t1 from the probability density function f (x 1). Specifically, when the subject can recognize the optotype with a predetermined luminance (t 1(dB) here), the inspection value obtained finally is estimated to be approximately t1(dB) or more. Therefore, for probability densities less than t1(dB) in the probability density function f (x1), an exclusion or reduction may be performed.
On the other hand, when the result of t1 or more is not obtained, the probability density function f (x2) is obtained by reducing the probability density of t1 or more from the probability density function f (x 1). Specifically, when the subject cannot recognize the optotype with a predetermined luminance (t 1(dB) here), the inspection value finally obtained is predicted to be approximately less than t1 (dB). Therefore, the probability density above t1(dB) in the probability density function f (x1) can be excluded or reduced.
After the probability density is eliminated or reduced, the probability density function f (x2) may be obtained by converting the total of the probability densities of all the values of x2 back to 100%.
The specific method of reducing the probability density from the probability density function f (x1) may be arbitrary. For example, the response function may be multiplied by the probability density function f (x1) to reduce the probability density.
For example, when the probability density is reduced to less than t1, the probability density function f (x1) may be a value that is proportional to a linear function, that is, a value obtained by multiplying x1 by 0, which is obtained by subtracting more than 3dB from t1, a value obtained by multiplying x1 by 1, which is obtained by adding more than 3dB from t1, and a value that is proportional to a linear function, which is a value between-1 and +1, which is multiplied by x1 in the range of ± 3dB of
Conversely, when the probability density is decreased by t1 or more, the probability density function f (x1) may be a value that is inversely proportional to a value between-1 and +1 multiplied by x1 subtracted by more than 3dB from t1, multiplied by 0 multiplied by x1 added by more than 3dB from t1, and multiplied by a value between-3 and +1 multiplied by x1 in the range of ± 3dB of t1, in a substantially linear function.
Incidentally, the response function used after the second and subsequent visual field examinations may use a function obtained by deforming the above-described response function or another function.
For example, as shown in the example described later, in the case after the second visual field test, the intersection of the response function in the case of visual recognition and the response function in the case of visual recognition may be set to be the stimulus threshold t2 (
Furthermore, a "response function in the case of visual recognition" having a value between-1 and +1 for x1 in the range of ± 3dB of t1 and being substantially proportional to a linear function, and a "response function in the case of non-visual recognition" having a value between-1 and +1 for x1 in the range of ± 3dB of t1 and being substantially inversely proportional to a linear function can be created.
The value of ± 3dB is only an example, and may be ± 1dB to 10 dB.
The response function is not limited to the above-described embodiment as long as it can eliminate or reduce the unnecessary probability density.
Also, instead of multiplying by the response function, the probability density above the stimulation threshold t1 or below the stimulation threshold t1 may be removed in such a way as to leave the
1-5. determination section
The determination step (5) is performed by the determination unit. In this step, it is determined whether or not the standard deviation σ of the probability density function f (x2) is in a state of being smaller than a predetermined value.
When the standard deviation σ has converged to a state smaller than the predetermined value, the inspection is terminated by regarding the value of x2 having the highest probability density in the probability density function f (x2) as the inspection value. The value of x2 having the highest probability density in a state where the standard deviation σ is smaller than the predetermined value is highly likely to be the actual test value of the subject. Therefore, the time required for the visual field inspection can be shortened and an accurate inspection value can be obtained.
The predetermined value may be set appropriately to be, for example, 0.5dB to 10.0 dB. The predetermined value may be set by an equation. For example, in example 1 described later, the predetermined value is set using the following equation.
Standard deviation σ ═ abs (20-x) — (0.1) +4.0
The value of x used in this equation may be x2 which is an average value of the probability density function f (x2) already created in the determination step (5), x2 which is a central value, or x2 which is a mode value as employed in the later-described example, i.e., which has the highest probability density. As used in the examples described later, the predetermined value may be changed according to the values of x2, x3, and x4 each time the steps (2), (3), (4), and (5) are repeated. Of course, the predetermined value may be a fixed value.
When x4 is the final inspection value (estimated threshold), x3 is not the final inspection value in a strict sense. On the other hand, the value obtained after one check is determined. Therefore, considering the actual results used for determining the predetermined value as the standard deviation σ, the x3 may be regarded as the item "estimation threshold value used in the visual field inspection in the past" in the first probability density function acquisition step (1), and the data in which the inspection value of the next time of the x3 is the x4 may be accumulated as a part of the big data. Similarly, the x2 may be regarded as "an estimation threshold used in the visual field inspection in the past" and the data having the x3 as the inspection value of the x2 in the next inspection may be accumulated as a part of the big data. This can increase the speed of accumulating large data, and further, the visual field inspection device of the present embodiment can obtain a more accurate inspection value.
The above expression may be modified according to the items used in the first probability density function acquisition step (1), or another expression may be used.
On the other hand, if the standard deviation σ does not converge to be smaller than the predetermined value, the above steps (2), (3), (4), and (5) are repeated again. When repeated, the following substitutions are made with respect to the descriptions of the above steps (2), (3), (4), and (5).
Replace the first time with the second time.
Replace x2 with
Replace x1 with
Replace the stimulation threshold t1 with
Replacing the second probability density function acquisition step with the third probability density function acquisition step.
The above steps (2), (3), (4), and (5) are repeated in this order until it is determined that the standard deviation σ of the probability density function f (x3) formed by reducing the probability density according to the inspection result has converged to a state smaller than a predetermined value. The number of times the steps (2), (3), (4), and (5) are performed is preferably set to three or less (three cycles or less) to further shorten the inspection time.
The control computer portion provided in the visual field inspection device may control each portion including the repetition of the steps (2), (3), (4), and (5).
<2. method for controlling visual field inspection apparatus >
The technical features of the present invention are also reflected in a control method of a visual field inspection apparatus using <1. visual field inspection apparatus > described above. Specifically, the visual field inspection device of the present embodiment controls the computer unit so that the above-described respective units execute the steps (1), (2), (3), (4), and (5), thereby obtaining the effects of the present invention.
<3. Vision examination procedure >
The technical features of the present invention are also reflected in the visual field inspection program of <1. visual field inspection apparatus > described above executed by a computer apparatus. Specifically, the visual field inspection program of the present embodiment is a program that causes a computer device to function as the first probability density function acquisition unit, the stimulus threshold determination unit, the inspection result acquisition unit, the second probability density function acquisition unit, and the determination unit described above. The contents of determination in the determination unit are the same as those described in <2. visual field inspection apparatus >, and therefore, are omitted.
<4 > effects of the embodiment
In the present embodiment, the termination condition for converging the examination is determined based on the result value and the big data obtained by the first visual field examination actually performed.
Thus, it is possible to provide a visual field inspection device, a control method for the visual field inspection device, and a visual field inspection program, which shorten the time required for visual field inspection and obtain an accurate inspection value.
<5. modified example, etc. >
The present invention is not limited to the above-described embodiments, and can be modified as appropriate without departing from the spirit and scope thereof. Further, the above-described respective configurations or preferred embodiments may be combined.
In the present embodiment, the stimulation threshold t1 may be determined in any manner as long as the probability densities of the probability density function f (x1) are separated. Here, an arithmetic unit (a program for controlling and executing the arithmetic unit) may be separately provided, and the arithmetic unit performs an arithmetic process of calculating t1 in which the number of times of visual field inspection is minimum by arithmetic operation, so as to effectively reduce the probability density unnecessary in (4).
Specifically, the inverse calculation is performed such that the standard deviation σ of the probability density function finally converges to a predetermined value (for example, 1.0dB to 3.5 dB). The number of tests when specific values were set for the stimulus threshold t1 in the first visual field test, the stimulus threshold t2 in the second visual field test, and the stimulus threshold t3 in the third visual field test was simulated. Furthermore, a stimulation threshold value at which the number of visual field tests is minimum may be set from the simulation result.
In the present embodiment, a probability density function under the condition that at least two items of each item such as the number of years elapsed since the previous examination are used is obtained. On the other hand, a probability density function under the condition that at least one of the items is adopted can also be obtained. Among them, the plurality of items used are more capable of reflecting the individual condition of the subject on the stimulation threshold value, and more accurate examination values are obtained.
In the present embodiment, a case of performing a visual field inspection is exemplified. On the other hand, the visual inspection is not limited to the visual field inspection as long as it is determined whether or not the visual target can be recognized using an arbitrary threshold value.