Program, visual acuity estimation device, and visual acuity estimation system

Abstract

Provided is a program capable of quickly estimating visual acuity without difficulty.　This program causes a processor to function as: a display control unit for displaying, on a display unit, an object being viewed by a subject; and an estimation unit for estimating the visual acuity of the subject on the basis of eye movements of the subject when tracking the object with the eyes.

Description

Program, Visual Acuity Estimation Device, and Visual Acuity Estimation System

[0001] The present invention relates to a program, a visual acuity estimation device, and a visual acuity estimation system.

[0002] Conventionally, a method for measuring visual acuity has been known (see, for example, Non-Patent Document 1). The method disclosed in Non-Patent Document 1 is MNREAD-J. In MNREAD-J, a chart on which a document is printed is presented to the measurement subject, the measurement subject reads aloud the document printed on the chart, the number of characters that the measurement subject fails to read is counted by the measurer, the reading visual acuity is measured based on the counted number of characters, and the visual acuity of the measurement subject is measured based on a table in which the reading visual acuity and the decimal visual acuity are associated.

[0003] Koichi Oda, "MNREAD-J, Jk Chart Manual", [online], May 18, 2002, [searched on September 17, 2014], Internet <URL: http: / / www.cis.twcu.ac.jp / ~k-oda / MNREAD-J / MNREAD-J-JkMan020518.pdf>

[0004] However, the method disclosed in Non-Patent Document 1 has a problem that it takes time and effort to measure visual acuity because the measurement subject reads aloud the document printed on the chart and the measurer counts the number of characters that the measurement subject fails to read. The present invention has been made in view of the above circumstances, and an object thereof is to provide a program, a visual acuity estimation device, and a visual acuity estimation system that can estimate visual acuity quickly without taking time and effort.

[0005] To achieve the above object, one aspect of the present invention is a program that causes a processor to function as a display control unit that displays an object to be viewed by a subject on a display unit, and an estimation unit that estimates the visual acuity of the subject based on the eye movement of the subject when tracking the object with the eyes. This specification shall include all the contents of Japanese Patent Application No. 2024-229909 filed on December 26, 2024.

[0006] According to the present invention, there is an effect that visual acuity can be estimated quickly without taking time and effort.

[0007] Figure 1 shows the configuration of the visual acuity estimation system. Figure 2 shows an example of a document displayed by the visual acuity estimation device. Figure 3 shows the configuration of the visual acuity estimation device. Figure 4 shows an example of a subject's eye movements as they read a document. Figure 5 shows an example of a subject's eye movements as they read a document. Figure 6 shows the relationship between reading speed and degree of myopia. Figure 7 is a flowchart showing the operation of the visual acuity estimation device. Figure 8 shows the configuration of the visual acuity estimation system. Figure 9 shows the estimation accuracy of the visual acuity estimation device. Figure 10 shows the configuration of the visual acuity estimation system.

[0008] [1. Configuration of the Visual Acuity Estimation System] First, the first embodiment will be described. Figure 1 is a diagram showing the configuration of the visual acuity estimation system 1. The visual acuity estimation system 1 is a system that estimates the visual acuity of a subject P1. The visual acuity estimation system 1 is also a system that recommends replacing the eyeglasses GL worn by subject P1 according to the estimated visual acuity. In this embodiment, the case where subject P1 is a child is used as an example. In this embodiment, the visual acuity estimation system 1 recommends that subject P1's parent P2 replace the eyeglasses GL.

[0009] The visual acuity estimation system 1 includes a visual acuity estimation device 2. In this embodiment, a portable PC (Personal Computer) such as a smartphone or tablet terminal is used as the visual acuity estimation device 2. The visual acuity estimation device 2 is a device that estimates the visual acuity of the subject P1. The visual acuity estimation device 2 also recommends replacing the glasses GL according to the estimated visual acuity. The visual acuity estimation device 2 is connected to a network NW such as the Internet. Therefore, in this embodiment, the visual acuity estimation device 2 recommends replacing the glasses GL by sending an email D1 to the parent P2 of the subject P1 via a mail server 3 connected to the network NW. The parent P2's email address is stored in the visual acuity estimation device 2 in advance.

[0010] Figure 1 shows an example of how the visual acuity estimation device 2 is used when estimating visual acuity. The visual acuity estimation device 2 displays a document BS consisting of multiple lines G via a touch panel 21. When the visual acuity estimation device 2 displays the document BS, the subject P1 reads the displayed multiple lines G one line at a time. The visual acuity estimation device 2 uses a camera 22 to photograph both of the subject P1's eyes E as they read the multiple lines G, and detects the eye movements of the subject P1 for each of the right eye RE and left eye LE as they read the document BS. The visual acuity estimation device 2 then estimates the subject P1's visual acuity based on at least one of the detected eye movements of the subject P1 and the reading speed, which indicates the number of characters read by the subject P1 in a predetermined time (e.g., 1 minute). The document BS is an example of an "object". Reading the document BS is an example of "looking at an object". Reading the document BS is an example of "following an object with your eyes".

[0011] Figure 2 shows an example of a document BS displayed by the visual acuity estimation device 2. Multiple lines G are displayed line by line in the Y direction in the figure. The Y direction is approximately parallel to the side of the display surface 21A when the subject P1 views the display surface 21A of the touch panel 21. Each line G has a string of characters in the X direction in the figure, which is perpendicular to the Y direction in the figure. In other words, in this embodiment, the document BS is a horizontally written document. The characters that make up the document BS may consist only of hiragana, only of katakana, only of kanji, or only of the alphabet, but in this embodiment, since the subject P1 is a child, it is preferable that the characters are of a type that a child can read. For example, assuming that a child can read a book on their own in the first grade of elementary school, it is preferable that the characters that make up the document BS consist of hiragana, katakana, and kanji that a first grader can read.

[0012] [2. Configuration of the Visual Acuity Estimation Device] Figure 3 shows the configuration of the visual acuity estimation device 2. The visual acuity estimation device 2 comprises a control device 20, a touch panel 21 (display unit), a camera 22, and a communication unit 23.

[0013] The control device 20 is a device that controls each part of the visual acuity estimation device 2. The control device 20 includes a processor 200 such as a CPU (Central Processing Unit), a memory 210, and an interface circuit for connecting other devices and sensors, and controls each part of the visual acuity estimation device 2.

[0014] Memory 210 is a storage device that stores programs and data. Memory 210 stores APP 211 (programs) and data processed by the processor 200. Memory 210 has a non-volatile storage area. Memory 210 also has a volatile storage area that constitutes the work area of ​​the processor 200. Memory 210 is composed of, for example, ROM (Read Only Memory) and RAM (Random Access Memory).

[0015] APP211 is an application program that causes the processor 200 to run as a functional unit, as described later. APP211 may be an application program pre-stored by the visual acuity estimation device 2, or an application program installed by the visual acuity estimation device 2 from the network.

[0016] The touch panel 21 comprises a display panel such as a liquid crystal display panel and a touch sensor that is superimposed on or integrated with the display panel. The display panel displays various information according to the control of the control device 20. The touch sensor detects touch operations and outputs them to the control device 20. The control device 20 executes processing corresponding to the touch operation based on the input from the touch sensor.

[0017] Camera 22 takes pictures according to the control of the control device 20. Camera 22 outputs the captured image obtained from the shooting to the control device 20.

[0018] The communication unit 23 is equipped with communication hardware such as an antenna and a communication circuit, and communicates with devices connected to the network NW in accordance with a predetermined communication standard.

[0019] The processor 200 functions as a document display unit 201, a detection unit 202, an estimation unit 203, and a recommendation unit 204 by reading and executing the APP 211 from the memory 210. The document display unit 201 is an example of a "display control unit".

[0020] [2-1. Document Display Unit] The document display unit 201 displays the document BS via the touch panel 21. The document BS displayed by the document display unit 201 may be a document BS stored in the memory 210, or a document BS downloaded from the network NW. Furthermore, the document BS displayed by the document display unit 201 may be different from the document BS displayed previously. For example, if a portion of a book's document BS is to be displayed, the document display unit 201 will make the document BS to be displayed this time different from the portion of the book that was displayed previously.

[0021] [2-2. Detection Unit] The detection unit 202 detects the gaze position of the subject P1 as they read the displayed document BS, using known eye-tracking techniques for both the left eye LE and the right eye RE.

[0022] The detection unit 202 detects the gaze position on the display surface 21A in the Y and X directions for the left eye LE and the right eye RE, respectively, based on the captured image taken by the camera 22. As described above, known eye tracking methods are used to detect the gaze position. For example, the detection unit 202 detects the gaze position on the display surface 21A from the correspondence between the captured image and the display surface 21A, based on the position of the pupil relative to the position of the inner corner of the eye in the captured image. In this example, a visible light camera is used for camera 22. Alternatively, for example, the detection unit 202 detects the gaze position on the display surface 21A from the correspondence between the captured image and the display surface 21A, based on the position of the pupil relative to the position of corneal reflection caused by infrared light irradiation. In this example, an infrared camera is used for camera 22.

[0023] Furthermore, each time the detection unit 202 detects a gaze position, it also detects the elapsed time since the start of gaze position detection. The timing for starting gaze position detection may be when the document BS is displayed, or when a predetermined time has elapsed since the document BS was displayed. This predetermined time is the time from when the document BS is displayed until it can be considered that the subject P1 has started reading the document BS, and is appropriately determined by prior tests or simulations.

[0024] The detection unit 202 detects at least one of the following based on the detected gaze position: lingering gaze, saccadic eye movements, and reading speed.

[0025] [2-2-1. Pause] Pause is an eye movement in which the gaze position temporarily stops. When a person reads a string of characters, they move their gaze in units of blocks containing multiple characters. Therefore, the eye movements of subject P1 when reading document BS include eye movements in which the gaze position temporarily stops in order to read the string of characters contained in one block.

[0026] Figure 4 shows an example of eye movement of subject P1 as they read through document BS. Figure 4 shows the experimental results obtained by the inventor of the present invention. The experimental results shown in Figure 4 show the eye movement of the fully corrected left eye LE when reading document BS, which consists of 17 lines G.

[0027] In Figure 4, a heatmap is superimposed on the document BS. In Figure 4, locations where data stagnation occurs are indicated by roughly circular, semi-transparent objects OJ, and the length of the stagnation time (hereinafter referred to as "stagnation time") is indicated by the color of the object OJ. In Figure 4, the darker the color of the object OJ, the longer the stagnation time.

[0028] As shown in Figure 4, it can be seen that the eye movements of subject P1 as they read through document BS include many pauses.

[0029] The detection unit 202 detects each of the detected gaze positions that differ from each other as a stationary position.

[0030] When the detection unit 202 detects a stop, it detects the stop duration for each detected stop. In other words, the detection unit 202 detects the time the line of sight position is stationary for each detected stop. The detection unit 202 detects the stop duration based on the elapsed time detected for each line of sight position.

[0031] Furthermore, when the detection unit 202 detects a pause, it detects the number of pauses included in the eye movements of the subject P1 as they read through document BS. The detection unit 202 determines the number of pauses detected from the gaze position as the number of pauses included in the eye movements of the subject P1 as they read through document BS.

[0032] [2-2-2. Saccadic Eye Movements] Saccadic eye movements, also known as saccades, are rapid and saccadic eye movements. As mentioned above, when people read text, they move their gaze in blocks. Therefore, the eye movements of subject P1 reading document BS include saccadic eye movements that move the gaze to the next block.

[0033] In Figure 4, the distance between adjacent objects OJ in the same line G represents the width of one saccadic eye movement. Also in Figure 4, in the direction of reading document BS, the distance between the object OJ at the end of one line G and the object OJ at the beginning of the next line G represents the width of one saccadic eye movement. As shown in Figure 4, it can be seen that the eye movements of subject P1 when reading document BS include many saccadic eye movements.

[0034] The detection unit 202 detects saccadic eye movements based on the detected gaze position. When the detection unit 202 detects saccadic eye movements, it detects the number of characters contained within the width of one saccadic eye movement (hereinafter referred to as "saccadic width character count" as appropriate). The detection unit 202 detects the saccadic width character count by plotting the detected gaze positions on the displayed document BS. For example, suppose the number of characters between the gaze position corresponding to object OJ1 in Figure 4 and the gaze position corresponding to object OJ2 in Figure 4 is "7". In this case, the detection unit 202 detects that the saccadic width character count between the gaze position corresponding to object OJ1 and the gaze position corresponding to object OJ2 is "7". The saccadic width character count is an example of "information quantity".

[0035] [2-2-3. Reading Speed] Reading speed indicates the number of characters read by subject P1 in a predetermined time. One minute is given as an example of this predetermined time, but this predetermined time is not limited to one minute and may be shorter or longer than one minute.

[0036] The detection unit 202 refers to the detected elapsed time to identify a certain gaze position and a gaze position a predetermined time after that gaze position. Next, the detection unit 202 detects the number of characters contained between the identified gaze positions in the direction of reading document BS, and detects the number of characters as the reading speed. For example, suppose a gaze position corresponding to object OJ3 in Figure 4 is identified as a certain gaze position, and a gaze position corresponding to object OJ4 in Figure 4 is identified as a gaze position a predetermined time after that gaze position. In this case, the detection unit 202 detects the number of characters contained in lines G1 to G14 as the reading speed.

[0037] [2-3. Estimation Unit] The estimation unit 203 estimates the visual acuity of subject P1 based on at least one of the subject P1's eye movements and reading speed as they read through document BS. The estimation by the estimation unit 203 will be described in detail below.

[0038] [2-3-1. Estimation based on dwell time] When the detection unit 202 detects the dwell time, the estimation unit 203 estimates the visual acuity of the subject P1 based on the dwell time detected by the detection unit 202.

[0039] For example, the estimation unit 203 calculates the average of the dwell times detected by the detection unit 202. Next, the estimation unit 203 estimates the visual acuity of subject P1 by comparing the calculated average dwell time with a threshold set for each estimable visual acuity. The threshold compared with the average dwell time is set so that the longer the average dwell time, the lower the estimated visual acuity.

[0040] Furthermore, for example, the estimation unit 203 calculates the total dwell time detected by the detection unit 202. Next, the estimation unit 203 estimates the visual acuity of subject P1 by comparing the calculated total dwell time with thresholds set for each estimable visual acuity. The thresholds compared with the total dwell time are set from the same perspective as the thresholds compared with the average dwell time.

[0041] When the detection unit 202 detects the number of stops, the estimation unit 203 estimates the visual acuity of subject P1 based on the number of stops detected by the detection unit 202.

[0042] For example, the estimation unit 203 estimates the visual acuity of subject P1 by comparing the number of stops detected by the detection unit 202 with a threshold set for each estimated visual acuity. The threshold compared with the number of stops is set so that the more stops there are, the lower the estimated visual acuity.

[0043] The threshold used in estimation based on stationary data may be either a threshold obtained from large-scale data or a threshold statistically obtained from the data of individual subject P1.

[0044] Furthermore, the estimation unit 203 may perform estimation based on dwell time using AI (Artificial Intelligence). In this case, a trained model is constructed that learns visual acuity from at least one of the dwell time and the number of dwells, and the constructed trained model is stored in a memory area accessible to the processor 200 (such as memory 210 or a device connected to the network NW). The estimation unit 203 then inputs at least one of the dwell time and the number of dwells detected by the detection unit 202 into the trained model and performs estimation by obtaining visual acuity from the trained model.

[0045] Here, the estimation accuracy of the estimation unit 203 based on fixation will be described. FIG. 5 is a diagram showing an example of the eye movement of the subject P1 when reading the document BS. FIG. 5 is an experimental result obtained by the inventor of the present application in an experiment. The experimental result shown in FIG. 5 shows the eye movement of the right eye RE having a myopia degree of -2D (Diopter) when reading the same document BS as in FIG. 4.

[0046] In FIG. 5, as in FIG. 4, a heat map is superimposed on the document BS. In FIG. 5, as in FIG. 4, the location where fixation occurs is shown by a substantially circular and translucent object OJ, and the length of the fixation time is shown by the color of the object OJ.

[0047] As is clear from comparing FIG. 5 and FIG. 4, when the myopia degree is low, the overall fixation time is extended. A decrease in the myopia degree is a decrease in visual acuity. Therefore, as is clear from comparing FIG. 5 and FIG. 4, it can be seen that when the visual acuity is low, the overall fixation time is extended. As shown in FIGS. 5 and 4, since the fixation time is extended when the visual acuity is low, the estimation unit 203 can appropriately estimate the visual acuity of the subject P1 by estimating that the lower the visual acuity is as the fixation time is longer.

[0048] [2-3-2. Estimation Based on Saccadic Eye Movements] When the detection unit 202 detects saccadic eye movements, the estimation unit 203 estimates the visual acuity of the subject P1 based on the number of characters in the saccade width.

[0049] For example, the estimation unit 203 calculates the average of the number of characters in the saccade width detected by the detection unit 202. Next, the estimation unit 203 estimates the visual acuity of the subject P1 by comparing the calculated average of the number of characters in the saccade width with the threshold values set for each estimable visual acuity. Note that the threshold value to be compared with the number of characters in the saccade width is set such that the lower the average of the number of characters in the saccade width, the lower the estimated visual acuity. This threshold value may be a threshold value statistically obtained from large-scale data or a threshold value statistically obtained from the data of the individual subject P1.

[0050] Alternatively, the estimation unit 203 may perform estimation based on saccadic eye movements using AI. In this case, a trained model is constructed that learns visual acuity from the number of saccadic characters, and the constructed trained model is stored in a memory area accessible to the processor 200. Then, the estimation unit 203 inputs the average number of saccadic characters into the trained model and performs estimation by obtaining visual acuity from the trained model.

[0051] Here, using Figures 4 and 5, the estimation accuracy of the estimation unit 203 based on saccadic eye movements will be explained. As is clear from comparing Figure 5 and Figure 4, saccadic eye movements occur more frequently when the degree of myopia is low, and the number of characters that can be read at once is small. As shown in Figures 5 and 4, the number of saccadic character widths decreases when visual acuity is low, so the estimation unit 203 can appropriately estimate the visual acuity of subject P1 by estimating lower visual acuity the fewer saccadic character widths there are.

[0052] [2-3-3. Estimation based on reading speed] When the detection unit 202 detects the reading speed, the estimation unit 203 estimates the visual acuity of subject P1 based on the reading speed detected by the detection unit 202. The estimation unit 203 estimates a lower visual acuity for subject P1 the lower the reading speed.

[0053] For example, the estimation unit 203 estimates the visual acuity of subject P1 by comparing the reading speed detected by the detection unit 202 with a threshold set for each estimable visual acuity. The threshold compared with the reading speed is set so that the higher the reading speed, the lower the estimated visual acuity. This threshold may be a threshold statistically obtained from large-scale data, or a threshold statistically obtained from the individual data of subject P1.

[0054] The estimation unit 203 may perform estimation based on reading speed using AI. In this case, a trained model is constructed by learning visual acuity from reading speed, and the constructed trained model is stored in a memory area accessible to the processor 200. The estimation unit 203 then inputs the reading speed into the trained model and performs estimation by obtaining visual acuity from the trained model.

[0055] Here, we will explain the estimation accuracy of the estimation unit 203 based on reading speed. Figure 6 is a diagram showing the relationship between reading speed and myopia degree. Figure 6 shows the experimental results obtained by the inventor of the present invention in an experiment.

[0056] In Figure 6, the horizontal axis is set to the degree of myopia. On the horizontal axis, the word "Emmetropia" refers to an emmetropic eye, meaning an eye that can see clearly at a distance without glasses or glasses. The degree of myopia is in increments of 0.25D, with "Mypia1D" representing a state where myopia has progressed four steps from an emmetropic eye, and "Mypia2D" representing a state where myopia has progressed eight steps from an emmetropic eye.

[0057] In Figure 6, the vertical axis is set to represent the rate of change in reading speed. In the vertical axis shown in Figure 6, the reading speed obtained when reading document BS with normal vision is set to 100%.

[0058] As can be seen from graph GF1 in Figure 6, reading speed decreases by approximately 10% when myopia progresses four steps from normal vision, and by approximately 30% when myopia progresses eight steps from normal vision. A decrease in the degree of myopia is equivalent to a decrease in visual acuity. Therefore, the estimation unit 203 can accurately estimate visual acuity by estimating a lower visual acuity as reading speed decreases.

[0059] The estimation unit 203 described above estimates visual acuity based on either eye retention, saccadic eye movements, or reading speed. However, the estimation unit 203 may estimate the visual acuity of subject P1 based on any combination of eye retention, saccadic eye movements, and reading speed.

[0060] For example, the estimation unit 203 may estimate the visual acuity of subject P1 based on eye retention and saccadic eye movements. In this case, the estimation unit 203 estimates visual acuity based on eye retention, as described above, and also estimates visual acuity based on saccadic eye movements, as described above. The estimation unit 203 then calculates the average of the two estimated visual acuities and estimates the calculated average as the visual acuity of subject P1.

[0061] Alternatively, for example, the estimation unit 203 may estimate the visual acuity of subject P1 based on eye retention, saccadic eye movements, and reading speed. In this case, the estimation unit 203 estimates visual acuity based on eye retention, saccadic eye movements, and reading speed, as described above. The estimation unit 203 then calculates the average of the three estimated visual acuities and estimates the calculated average as the visual acuity of subject P1.

[0062] [2-4. Recommendation Section] The recommendation section 204 recommends that the parent P2 of the target person P1 replace their eyeglasses GL by sending email D1. For example, the recommendation section 204 sends email D1 to the parent P2 with the message, "It appears your child's eyesight is deteriorating. We recommend that your child replace their eyeglasses."

[0063] The recommendation unit 204 sends email D1 if the visual acuity estimated by the estimation unit 203 is below a predetermined threshold. Here, the predetermined threshold is 0.4. This predetermined threshold is determined from the following perspectives: If the visual acuity of both eyes is 0.6 or higher, the ophthalmologist is unlikely to prescribe eyeglasses GL as it will be monitored. If the visual acuity of both eyes is 0.4 or higher, the ophthalmologist may or may not prescribe eyeglasses GL. If the visual acuity of both eyes is 0.2 or lower, the ophthalmologist will prescribe eyeglasses GL. Therefore, by setting the predetermined threshold to 0.4, the ophthalmologist can recommend replacing eyeglasses GL at a visual acuity higher than the visual acuity at which eyeglasses GL are prescribed, thus recommending replacement of eyeglasses GL before visual acuity has significantly deteriorated.

[0064] [3. Operation] Next, the operation of the visual acuity estimation device 2 according to this embodiment will be described. Figure 7 is a flowchart showing the operation of the visual acuity estimation device 2.

[0065] Examples of start conditions in the flowchart shown in Figure 7 include when APP211 is launched, or when there is input to start displaying document BS after APP211 has been launched.

[0066] The document display unit 201 displays document BS on the touch panel 21 (step S1).

[0067] Next, the detection unit 202 detects at least one of the following: eye retention, saccadic eye movements, and reading speed (step S2).

[0068] Next, the estimation unit 203 estimates the visual acuity of the subject P1 (step S3).

[0069] The recommendation unit 204 determines whether the visual acuity estimated in step S3 is below a predetermined threshold (step S4).

[0070] If the recommendation unit 204 determines that the visual acuity estimated in step S3 is below a predetermined threshold (step S4: YES), it sends email D1 (step S5).

[0071] On the other hand, if the recommendation unit 204 determines that the visual acuity estimated in step S3 exceeds a predetermined threshold (step S4: NO), the processor 200 terminates this process.

[0072] [4. Effects of this Embodiment] As described above, the visual acuity estimation device 2 estimates the visual acuity of subject P1 based on at least one of the subject P1's eye movements and reading speed as they read through document BS. Therefore, compared to MNREAD-J, there is no need for subject P1 to read document BS aloud or for someone other than subject P1 to count the number of characters that subject P1 has misread. Thus, subject P1's visual acuity can be estimated quickly and without any hassle.

[0073] Furthermore, the visual acuity estimation device 2 estimates the visual acuity of subject P1, and if the estimated visual acuity is below a predetermined threshold, it recommends replacing the eyeglasses GL. Generally, eyeglasses GL are replaced mainly when they become difficult to see with, when they are damaged, or when the lenses deteriorate. Therefore, by the time an eyeglasses GL is considered for replacement, there is a possibility that the visual acuity has already deteriorated significantly. By recommending the replacement of eyeglasses GL, subject P1 can wear eyeglasses GL that are suitable for them before their visual acuity deteriorates significantly. As mentioned above, poor visual acuity reduces reading speed. In other words, the lower the visual acuity, the less information can be obtained from reading per unit time. This leads to a handicap in information acquisition, and in children, it leads to a handicap in learning. However, in this embodiment, since eyeglasses GL can be replaced before visual acuity deteriorates significantly, these handicaps can be eliminated.

[0074] [5. Second Embodiment] Next, a second embodiment will be described. In describing the second embodiment, the differences from the first embodiment described above will be mainly explained. Also, in describing the second embodiment, the same reference numerals will be used for the components of each part of the first embodiment described above, and detailed descriptions will be omitted as appropriate.

[0075] Figure 8 shows the configuration of the visual acuity estimation system 1A. Similar to the visual acuity estimation system 1, the visual acuity estimation system 1A is a system that estimates the visual acuity of subject P1. The visual acuity estimation system 1A is also a system that outputs information regarding the suitability of contact lenses to be worn by subject P1, according to the estimated visual acuity. In this embodiment, subject P1 may be a child or an adult. The information regarding the suitability of contact lenses includes information regarding the power of the contact lenses, information regarding the type of contact lenses, and information regarding the prescription of the contact lenses. In this embodiment, as information regarding the type of contact lenses, information recommending a change in the power of the contact lenses is given as an example.

[0076] The visual acuity estimation system 1 includes a visual acuity estimation device 2A. In this embodiment, a portable PC such as a smartphone or tablet is exemplified as the visual acuity estimation device 2A. The visual acuity estimation device 2A is a device that estimates the visual acuity of a subject P1. The visual acuity estimation device 2A is connected to a network NW such as the Internet. The visual acuity estimation device 2A recommends changing the contact lens prescription according to the estimated visual acuity. The visual acuity estimation device 2A makes recommendations by displaying information or by sending email D1 via the mail server 3. When the visual acuity estimation device 2A makes recommendations by sending email D1, for example, if the subject P1 is a child, it sends email D1 to the parent P2, and if the subject P1 is an adult, it sends email D1 to the subject P1 themselves or to people related to the subject P1 (e.g., relatives or caregivers). The email addresses of the emails D1 sent by the visual acuity estimation device 2A are stored in the visual acuity estimation device 2A in advance.

[0077] In this embodiment, with subject P1 wearing contact lenses, the visual acuity estimation device 2A estimates subject P1's visual acuity. Similar to the visual acuity estimation device 2, the visual acuity estimation device 2A displays document BS, photographs both of subject P1's eyes E as they read the document BS using camera 22, and detects the eye movements of subject P1 as they read the document BS for both the right eye RE and the left eye LE. Then, similar to the visual acuity estimation device 2, the visual acuity estimation device 2A estimates subject P1's visual acuity based on at least one of the detected eye movements of subject P1 and the reading speed, which indicates the number of characters read by subject P1 in a predetermined time.

[0078] As is clear from comparing Figure 8 with Figure 3, in the second embodiment, compared to the first embodiment described above, the memory 210 of the visual acuity estimation device 2A stores APP211A. Also, as is clear from comparing Figure 8 with Figure 3, in the second embodiment, compared to the first embodiment described above, the processor 200 of the visual acuity estimation device 2A reads and executes APP211A, so that the processor 200 functions as the document display unit 201, the detection unit 202, the estimation unit 203, and the recommendation unit 204A. APP211A is an example of a "program". The recommendation unit 204A is an example of an "output unit".

[0079] The recommendation unit 204A recommends changing the contact lens prescription by displaying information on the touch panel 21 or by sending an email D1. For example, the recommendation unit 204A displays the message "Your contact lens prescription is incorrect. We recommend changing your contact lens prescription" on the touch panel 21. Alternatively, the recommendation unit 204A may send an email D1 containing the message "Your contact lens prescription is incorrect. We recommend changing your contact lens prescription."

[0080] The recommendation unit 204A recommends changing the contact lens power if the visual acuity estimated by the estimation unit 203 is below a predetermined threshold. This predetermined threshold may be the same as that of the embodiment described above. Alternatively, this predetermined threshold may be determined from the perspective of ophthalmic prescriptions for contact lenses, similar to the perspective of eyeglasses GL.

[0081] Next, the estimation accuracy of the visual acuity estimation device 2A will be explained. Figure 9 shows the estimation accuracy of the visual acuity estimation device 2A. Figure 9 shows the experimental results obtained by the inventor of the present invention in experiments.

[0082] In Figure 9, the vertical axis represents minority visual acuity. In Figure 9, "Actual" on the horizontal axis represents the measured value, and "Pred" on the horizontal axis represents the estimated value by the visual acuity estimation device 2A. In Figure 9, the visual acuity of two subjects is plotted. Plots PR1 and PR2 show the visual acuity of the first subject while wearing contact lenses. Plot PR1 shows the measured value of the first subject's visual acuity while wearing contact lenses. Plot PR2 shows the value estimated by the visual acuity estimation device 2A for the first subject's visual acuity while wearing contact lenses. Plots PR3 and PR4 show the visual acuity of the second subject while wearing contact lenses. Plot PR3 shows the measured value of the second subject's visual acuity while wearing contact lenses. Plot PR4 shows the value estimated by the visual acuity estimation device 2A for the second subject's visual acuity while wearing contact lenses.

[0083] As can be seen from the difference between plots PR1 and PR2, and the difference between plots PR3 and PR4, the visual acuity estimated by the visual acuity estimation device 2 has an error of less than 0.1 compared to the measured visual acuity. Therefore, the visual acuity estimation device 2A, that is, the estimation unit 203 of the visual acuity estimation device 2A, is able to properly estimate the visual acuity of subject P1 while wearing contact lenses.

[0084] Next, the operation of the visual acuity estimation device 2A of this embodiment will be described. The document display unit 201 of the visual acuity estimation device 2A displays document BS by triggering in the same manner as the visual acuity estimation device 2. Then, the detection unit 202 of the visual acuity estimation device 2A detects at least one of the following: eye retention, saccadic eye movements, and reading speed, similar to the visual acuity estimation device 2. Then, the estimation unit 203 of the visual acuity estimation device 2A estimates the visual acuity of the subject P1.

[0085] The recommendation unit 204A then determines that the estimated visual acuity is below a predetermined threshold and recommends changing the contact lens prescription. On the other hand, the recommendation unit 204A does not recommend changing the contact lens prescription if it determines that the estimated visual acuity is above a predetermined threshold. In this case, the recommendation unit 204A may notify the user that the contact lenses being worn are appropriate, such as by displaying information or sending an email D1, indicating that the contact lenses are correct.

[0086] As described above, the visual acuity estimation device 2A of this embodiment estimates the visual acuity of a person P1 wearing contact lenses, and if the estimated visual acuity is below a predetermined threshold, it recommends changing the power of the contact lenses. As a result, person P1 can wear contact lenses that are suitable for them before their visual acuity deteriorates significantly. Furthermore, the visual acuity estimation device 2A of this embodiment can contribute to promoting the transition to new products and new materials of contact lenses that are less likely to cause visual deterioration.

[0087] Incidentally, there are multifocal contact lenses (hereinafter referred to as "multifocal contact lenses"). Multifocal contact lenses have different powers depending on the area of ​​the eye. Therefore, conventionally, visual acuity tests with multifocal contact lenses in place are difficult to perform accurately and take a long time because the power of the multifocal contact lenses varies depending on the area of ​​the eye, and the pupils move due to individual differences. However, the visual acuity estimation device 2A of this embodiment estimates the average visual acuity when reading document BS with appropriate accuracy, so it is possible to perform the test without having to worry as much about the state of wearing the multifocal contact lenses as before, and the test time can be shortened. Therefore, the visual acuity estimation device 2A of this embodiment can improve the outpatient turnover rate for multifocal contact lenses (the number of patients who can complete examinations, prescriptions, tests, etc. within a certain time), and in turn can contribute to the increased adoption of multifocal contact lenses.

[0088] Furthermore, there are contact lenses for astigmatism (hereinafter referred to as "astigmatism contact lenses"). With astigmatism contact lenses, a phenomenon may occur where the astigmatism correction axis within the lens shifts from its original position (hereinafter referred to as "axis misalignment"), which takes time to insert and thus prolongs the visual acuity test. However, the visual acuity estimation device 2A of this embodiment estimates the average visual acuity when reading document BS with appropriate accuracy, so the test can be performed without having to worry as much about the insertion state of the astigmatism contact lenses as before, thereby shortening the test time. Therefore, the visual acuity estimation device 2A of this embodiment can improve the turnover rate of outpatients related to astigmatism contact lenses, and in turn contribute to improving the introduction of astigmatism contact lenses.

[0089] [6. Third Embodiment] Next, a third embodiment will be described. In the description of the third embodiment, the differences from the embodiments described above will be mainly explained. Also, in the description of the second embodiment, the same reference numerals are used for the components of the parts of the embodiments described above, and detailed descriptions will be omitted as appropriate.

[0090] Figure 10 shows the configuration of the visual acuity estimation system 1B. Like the visual acuity estimation systems 1 and 1A, the visual acuity estimation system 1B is a system that estimates the visual acuity of a subject P1. In addition, the visual acuity estimation system 1B is a system that recommends that subject P1 visit an ophthalmologist located within a predetermined distance from their current location, based on the estimated visual acuity. In this embodiment, subject P1 may be a child or an adult.

[0091] The visual acuity estimation system 1 includes a visual acuity estimation device 2B. In this embodiment, a portable PC such as a smartphone or tablet is exemplified as the visual acuity estimation device 2B. The visual acuity estimation device 2B is a device that estimates the visual acuity of a subject P1. The visual acuity estimation device 2B is connected to a network NW such as the Internet. Based on the estimated visual acuity, the visual acuity estimation device 2B recommends that the subject P1 visit an ophthalmologist located within a predetermined distance from their current location. The visual acuity estimation device 2B makes recommendations by displaying information or by sending an email D1 via the mail server 3. When the visual acuity estimation device 2B makes recommendations via email D1, for example, if the subject P1 is a child, it sends email D1 to the parent P2, and if the subject P1 is an adult, it sends email D1 to the subject P1 themselves or to someone related to the subject P1 (e.g., a relative or caregiver). The email addresses of the emails D1 sent by the visual acuity estimation device 2B are stored in the visual acuity estimation device 2B in advance.

[0092] In this embodiment, with subject P1 wearing contact lenses, the visual acuity estimation device 2B estimates subject P1's visual acuity. Similar to visual acuity estimation devices 2 and 2A, the visual acuity estimation device 2B displays document BS, and the camera 22 captures both of subject P1's eyes E as they read document BS, detecting the eye movements of subject P1 for each of the right eye RE and left eye LE as they read document BS. Then, similar to visual acuity estimation devices 2 and 2A, the visual acuity estimation device 2B estimates subject P1's visual acuity based on at least one of the detected eye movements of subject P1 and the reading speed, which indicates the number of characters read by subject P1 in a predetermined time.

[0093] As is clear from comparing Figure 10 with Figure 3 or Figure 8, the visual acuity estimation device 2B of the third embodiment further includes a GNSS (Global Navigation Satellite System) unit 24. The GNSS unit 24 determines the current position of the visual acuity estimation device 2B. The GNSS unit 24 generates position data indicating the current position of the visual acuity estimation device 2B and outputs the generated position data to the control device 20.

[0094] Furthermore, as is clear from comparing Figure 10 with Figure 3 or Figure 8, in this embodiment, compared to the embodiment described above, the memory 210 of the visual acuity estimation device 2B stores APP211B. Also, as is clear from comparing Figure 10 with Figure 3 or Figure 8, in this embodiment, compared to the embodiment described above, the processor 200 of the visual acuity estimation device 2B reads and executes APP211B, so that the processor 200 functions as the document display unit 201, the detection unit 202, the estimation unit 203, and the recommendation unit 204B. APP211B is an example of a "program".

[0095] The recommendation unit 204B recommends that the subject P1 visit an ophthalmologist located within a predetermined distance from their current location by displaying information on the touch panel 21 or by sending an email D1. For example, the recommendation unit 204B displays the message "AAA Ophthalmology Clinic is close to your current location. We recommend that you visit AAA Ophthalmology Clinic" on the touch panel 21. Alternatively, the recommendation unit 204B may send an email D1 containing the message "AAA Ophthalmology Clinic is close to your current location. We recommend that you visit AAA Ophthalmology Clinic."

[0096] The recommendation unit 204B recommends that the subject P1 visit an ophthalmologist located within a predetermined distance from their current location if the visual acuity estimated by the estimation unit 203 is below a predetermined threshold. This predetermined threshold may be the same as that of each embodiment described above. Alternatively, this predetermined threshold may be determined from the perspective of recommending a visit to an ophthalmologist.

[0097] The recommendation unit 204B will now be described in detail. If the visual acuity estimated by the estimation unit 203 is below a predetermined threshold, the recommendation unit 204B acquires location data from the GNSS unit 24 and searches for an ophthalmologist located within a predetermined distance from the current location indicated by the acquired location data. For example, if the visual acuity estimation device 2B stores map data, the recommendation unit 204B refers to the map indicated by the map data and searches for an ophthalmologist located within a predetermined distance from the current location indicated by the acquired location data. Alternatively, for example, the recommendation unit 204B transmits the acquired location data to a predetermined server via the communication unit 23, queries the predetermined server for an ophthalmologist located within a predetermined distance from the current location indicated by the location data, and retrieves the ophthalmologist from the predetermined server. The predetermined server is a server that stores map data and has the function of searching for facilities, and is connected to a network NW. If an ophthalmologist is located within a predetermined distance from the current location of the visual acuity estimation device 2B, the recommendation unit 204B recommends visiting the searched ophthalmologist. If no ophthalmology clinic is located within a predetermined distance from the current position of the visual acuity estimation device 2B, the propulsion unit 204B may expand the search range and search again, or it may notify the user that no ophthalmology clinic is found by displaying information or sending an email D1.

[0098] Next, the operation of the visual acuity estimation device 2B of this embodiment will be described. The document display unit 201 of the visual acuity estimation device 2B displays document BS by triggering in the same manner as the visual acuity estimation devices 2 and 2A. Then, the detection unit 202 of the visual acuity estimation device 2B detects at least one of the following: eye retention, saccadic eye movements, and reading speed, similar to the visual acuity estimation devices 2 and 2A. Then, the estimation unit 203 of the visual acuity estimation device 2B estimates the visual acuity of the subject P1.

[0099] Then, if the recommendation unit 204B determines that the estimated visual acuity is below a predetermined threshold, it recommends that the subject P1 visit an ophthalmologist located within a predetermined distance from their current location.

[0100] [7. Other Embodiments] The embodiments described above are merely examples and can be modified and applied as needed.

[0101] In the first embodiment described above, the case where the target person P1 is a child was illustrated, and the case where the recommendation for replacing the eyeglasses GL is made to the parent P2 was illustrated. In other embodiments, the target person P1 may be an adult instead of a child. In this case, the recommendation unit 204 may recommend replacing the eyeglasses GL by displaying information on the touch panel 21 instead of sending an email D1.

[0102] In the embodiments described above, 0.4 was given as an example of a predetermined threshold value that serves as the criterion for the recommendation unit 204 to make a recommendation. However, this predetermined threshold value is not limited to 0.4, and may be 0.5 or 0.3.

[0103] In the first embodiment described above, the recommendation unit 204 is configured to recommend replacing the eyeglasses GL. However, if the target person P1 is a person who has never worn eyeglasses GL before, the recommendation unit 204 may recommend purchasing eyeglasses GL.

[0104] In the first embodiment described above, the recommendation unit 204 is configured to make recommendations via email D1. In other embodiments, the recommendation unit 204 may recommend replacing the glasses GL by printing, voice, or display. However, if the target person P1 is a child, the target person P1 may be ridiculed by other children as a result of the recommendation, so it is preferable to make recommendations by printing, voice, or display when the target person P1 is an adult. In other embodiments, the recommendation units 204A and 204B may make corresponding recommendations by printing, voice, etc.

[0105] In the first embodiment described above, the visual acuity estimation device 2 was exemplified as a portable PC. However, the visual acuity estimation device 2 is not limited to a portable PC, but may also be a desktop PC or a laptop PC. Furthermore, the visual acuity estimation device 2 may display document BS using a panel without touch functionality. Similarly, the visual acuity estimation devices 2A and 2B are not limited to portable PCs, but may also be desktop PCs or laptop PCs, and may display document BS using a panel without touch functionality.

[0106] In the first embodiment described above, the visual acuity estimation device 2 displays a document BS and the camera 22 captures both eyes E of the subject P1. However, the visual acuity estimation device 2 may be a device that does not have at least one of the document BS display function or the camera 22 capture function. If the device does not have a document BS display function, the visual acuity estimation device 2 displays the document BS using a separate display. If the device does not have a capture function, the visual acuity estimation device 2 captures both eyes E of the subject P1 using a separate camera. Furthermore, the visual acuity estimation device 2 does not have to display a document BS. In this case, for example, the visual acuity estimation device 2 acquires the gaze of the subject P1, who is reading a document BS printed on a printed medium, using an external camera or camera 22, and performs the visual acuity estimation and notification described above. Similarly, the visual acuity estimation devices 2A and 2B may be devices that do not have at least one of the document BS display function or the camera 22 capture function.

[0107] In the first embodiment described above, the processor 200 is configured to function as a document display unit 201, a detection unit 202, an estimation unit 203, and a recommendation unit 204. In other embodiments, for example, a server device connected to a network NW may perform at least one of the functions of the detection unit 202, the estimation unit 203, and the estimation unit 204. Furthermore, in other embodiments according to the second and third embodiments, for example, a server device connected to a network NW may perform at least one of the functions of the detection unit 202, the estimation unit 203, and the estimation unit 204.

[0108] In other embodiments, the recommendation unit 204 of the first embodiment may have at least one of the functions of recommendation unit 204A and 204B. When the recommendation unit 204 of the first embodiment has the function of recommendation unit 204B, the visual acuity estimation device 2 includes a GNSS unit 24. In other embodiments, the recommendation unit 204A of the second embodiment may have at least one of the functions of recommendation unit 204 and 204B. When the recommendation unit 204A of the second embodiment has the function of recommendation unit 204B, the visual acuity estimation device 2 includes a GNSS unit 24. In other embodiments, the recommendation unit 204B of the third embodiment may have at least one of the functions of recommendation unit 204 and 204A.

[0109] In the embodiment described above, the example shown was that document BS is a horizontally written document, but document BS may also be a vertically written document.

[0110] In the embodiments described above, the case where the "target" is a meaningful document BS was illustrated. In other embodiments, the "target" may consist of meaningless objects. For example, the "target" may consist of random strings of characters or a series of non-character objects (e.g., numbers, symbols, or marks). Alternatively, the "target" may consist of objects in motion. When the "target" consists of something other than characters, the detection unit 202 detects the distance of the gaze movement and the number of objects included in the width of one saccadic eye movement for each detected saccadic eye movement. The number of objects is an example of "information quantity". The estimation unit 203 then estimates the visual acuity using AI or the like based on the detected gaze movement distance and the number of objects. Since the width of saccadic eye movements differs depending on the visual acuity, the estimation unit 203 can appropriately estimate based on the gaze movement distance and the number of objects. When the "target" consists of something other than characters, the detection unit 202 identifies a certain gaze position and a gaze position a predetermined time after that gaze position, and detects the reading speed based on the two identified gaze positions. In this case, the reading speed can be interpreted not as the number of characters included in the two gaze positions, but as a speed that can be defined by the number of objects included in the two gaze positions, or by a predetermined time and the distance between the two gaze positions. The estimation unit 203 then estimates the visual acuity using AI or the like based on the detected reading speed.

[0111] In the second embodiment described above, the recommendation unit 204A was exemplified as the "output unit". In other embodiments of the second embodiment, the "output unit" may output information other than information recommending a change in contact lens power. That is, the "output unit" may output information regarding contact lens suitability, such as information regarding contact lens power, information regarding contact lens type, and information regarding contact lens prescription. Note that the output method of the "output unit" is not limited to display, but may also be audio output or print.

[0112] In other embodiments, the processor 200 may execute any of APP 211, 211A, or 211B, and if the visual acuity estimated by the estimation unit 203 is below a predetermined threshold, it may output a comparison result of the performance of the contact lenses. In this other embodiment, the memory 210 stores information about the performance of the contact lens currently in use (hereinafter referred to as the "first contact lens"), and the processor 200 outputs a comparison result (for example, the difference in performance or the superiority of the performance) between the performance of the first contact lens stored in the memory 210 and the performance of a contact lens other than the first contact lens (hereinafter referred to as the "second contact lens"). Examples of the second contact lens include a contact lens from a different manufacturer than the first contact lens, or a newer contact lens than the first contact lens. The processor 200 obtains information about the performance of the second contact lens by accessing a server device connected to the network NW, compares the performance of the first contact lens with the performance of the second contact lens, and outputs the comparison result. Alternatively, the processor 200 transmits performance information of the first contact lens to a server device connected to the network NW, obtains a comparison result between the performance of the first contact lens and the performance of the second contact lens from the server device, and outputs the obtained comparison result. The output of the comparison result may be displayed on the touch panel 21, output as audio, or printed.

[0113] In other embodiments, the estimation unit 203 may estimate visual acuity not only based on eye movements, but also on the pupil diameter and eyelid opening degree (how wide the eyes are open) of the subject P1 as they read through the document BS.

[0114] In the embodiments described above, the "program" of the present invention was exemplified as an application program, but the "program" of the present invention may also consist of a program that is part of the OS (Operating System) of the visual acuity estimation device 2.

[0115] The processor 200 may consist of multiple processors or a single processor. The processor 200 may also be hardware programmed to implement the functional units described above. In this case, the processor 200 may consist of, for example, an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array).

[0116] Furthermore, the configurations of the parts of the visual acuity estimation devices 2, 2A, and 2B shown in Figures 3, 8, and 10 are merely examples, and the specific implementation is not particularly limited. In other words, it is not necessarily required that hardware corresponding to each part be implemented individually, and it is certainly possible to configure the system so that a single processor executes a program to realize the functions of each part. Also, some of the functions realized by software in the above-described embodiments may be implemented as hardware, or some of the functions realized by hardware may be implemented as software.

[0117] Furthermore, the operation steps shown in Figure 7 are divided according to the main processing content, and the present invention is not limited by the way the processing units are divided or their names. Depending on the processing content, it may be further divided into more steps. Alternatively, it may be divided so that one step unit includes even more processing. Also, the order of the steps may be rearranged as appropriate, as long as it does not impede the spirit of the present invention.

[0118] Furthermore, since the embodiments described above are for illustrative purposes only, various modifications, substitutions, additions, omissions, etc., can be made within the scope of the claims or their equivalents.

[0119] [8. Configurations Supported by the Above Embodiments] The above embodiments support the following configurations.

[0120] (Configuration 1) A program that causes the processor to function as a display control unit that displays the object that the subject is looking at on the display unit, and an estimation unit that estimates the subject's visual acuity based on the subject's eye movements when the subject follows the object with their eyes.

[0121] According to the program in Configuration 1, the subject's visual acuity is estimated based on the subject's eye movements as they follow the object with their eyes. Therefore, the visual acuity is automatically estimated simply by the subject following the object with their eyes. As a result, there is no need for the subject to read the document aloud or for someone else to count the number of characters that the subject misreads. Thus, the subject's visual acuity can be estimated quickly and without any extra effort.

[0122] (Configuration 2) The program according to Configuration 1, wherein the eye movements of the subject include pauses, and the estimation unit estimates the subject's visual acuity based on at least one of the duration of pauses and the number of pauses.

[0123] According to the program in configuration 2, the duration and number of stops vary depending on the subject's visual acuity. Therefore, by estimating the visual acuity based on the duration and number of stops, the subject's visual acuity can be accurately estimated.

[0124] (Configuration 3) The program according to Configuration 1 or Configuration 2, wherein the eye movements of the subject include saccadic eye movements, and the estimation unit estimates the subject's visual acuity based on the amount of information contained in the width of one saccadic eye movement.

[0125] According to the program in configuration 3, the amount of information contained in the width of a single saccadic eye movement changes depending on the subject's visual acuity. By estimating visual acuity based on this amount of information, the subject's visual acuity can be accurately estimated.

[0126] (Configuration 4) A program according to any one of Configurations 1 to 3, wherein the processor functions as a recommendation unit that recommends replacing or purchasing new eyeglasses for the subject when the subject's visual acuity is below a predetermined threshold.

[0127] According to the program in configuration 4, it becomes possible to recommend replacing or purchasing glasses before eyesight deteriorates significantly, allowing individuals to wear glasses that are suitable for them before their vision deteriorates drastically. Therefore, it is possible to suppress the handicap that individuals may have in terms of the amount of information they can acquire.

[0128] (Configuration 5) The program according to any one of Configurations 1 to 4, wherein the subject is a child, and the recommendation unit recommends to the subject's parent that the subject purchase new glasses for the subject to wear.

[0129] According to the program in configuration 5, if the target person is a child, the recommendation is made to the target person's parent rather than the child, which increases the likelihood that the target person will be able to wear glasses that are suitable for them.

[0130] (Configuration 6) A program according to any one of Configurations 1 to 5, wherein the processor functions as an output unit that outputs information regarding the suitability of contact lenses used by the subject when the subject's visual acuity is below a predetermined threshold.

[0131] According to the program in configuration 6, information regarding the suitability of contact lenses can be output before a significant decline in visual acuity occurs, allowing the subject to wear contact lenses that are suitable for them before their visual acuity deteriorates significantly.

[0132] (Configuration 7) A program according to any one of Configurations 1 to 6, wherein the processor functions as a recommendation unit that recommends the subject visit an ophthalmologist located within a predetermined distance from the subject's current location when the subject's visual acuity is below a predetermined threshold.

[0133] According to the program in Configuration 7, if a subject's eyesight is deteriorating, they can easily identify a recommended ophthalmologist, increasing the likelihood of prompt medical attention. Furthermore, they can easily understand which ophthalmologists are closest to their current location, improving convenience for the subject.

[0134] (Configuration 8) A program according to any one of Configurations 1 to 7, which causes the processor to output a comparison result between the first contact lens currently being used by the subject and a second contact lens different from the first contact lens, when the subject's visual acuity is below a predetermined threshold.

[0135] According to the program in configuration 8, if a subject's eyesight has deteriorated, they can understand the comparison between the performance of their current contact lenses and the performance of other contact lenses, and then choose contact lenses that are suitable for them.

[0136] (Configuration 9) A visual acuity estimation device comprising: a display control unit that displays an object that the subject is looking at on a display unit; and an estimation unit that estimates the subject's visual acuity based on the subject's eye movements when the subject follows the object with their eyes.

[0137] According to the visual acuity estimation device of configuration 9, the subject's visual acuity is estimated based on the subject's eye movements as they track an object with their eyes. Therefore, the subject's visual acuity is automatically estimated simply by the subject tracking the object with their eyes. As a result, there is no need for the subject to read a document aloud or for someone else to count the number of characters that the subject misreads. Thus, the subject's visual acuity can be estimated quickly and without any extra effort.

[0138] (Configuration 10) A visual acuity estimation system comprising: a display control unit that displays an object that the subject is looking at on a display unit; and an estimation unit that estimates the subject's visual acuity based on the subject's eye movements when the subject follows the object with their eyes.

[0139] According to the visual acuity estimation system of configuration 10, the subject's visual acuity is estimated based on the subject's eye movements when tracking an object with their eyes. Therefore, the subject's visual acuity is automatically estimated simply by the subject tracking the object with their eyes. As a result, there is no need for the subject to read a document aloud or for someone other than the subject to count the number of characters that the subject misreads. Thus, the subject's visual acuity can be estimated quickly and without any extra effort.

[0140] 1, 1A, 1B Visual acuity estimation system 2, 2A, 2B Visual acuity estimation device 21 Touch panel (display unit) 200 Processor 201 Document display unit (display control unit) 203 Estimation unit 204 Recommendation unit 204A Recommendation unit (output unit) 204B Recommendation unit 211, 211A, 211B APP (program) BS Document (display target) P1 Target person P2 Parent

Claims

1. A program that causes a processor to function as a display control unit that displays an object viewed by the subject on a display unit, and an estimation unit that estimates the subject's visual acuity based on the subject's eye movements as they track the object.

2. The program according to claim 1, wherein the eye movements of the subject include pauses, and the estimation unit estimates the subject's visual acuity based on at least one of the duration of pauses and the number of pauses.

3. The program according to claim 1, wherein the eye movements of the subject include saccadic eye movements, and the estimation unit estimates the subject's visual acuity based on the amount of information contained in the width of one saccadic eye movement.

4. The program according to any one of claims 1 to 3, wherein the processor functions as a recommendation unit that recommends replacing or purchasing new eyeglasses for the subject when the subject's visual acuity is below a predetermined threshold.

5. The program according to claim 4, wherein the subject is a child, and the recommendation unit recommends the program to the parent of the subject.

6. The program according to any one of claims 1 to 3, wherein the processor functions as an output unit that outputs information regarding the suitability of contact lenses used by the subject when the subject's visual acuity is below a predetermined threshold.

7. The program according to any one of claims 1 to 3, wherein the processor functions as a recommendation unit that recommends the subject visit an ophthalmologist located within a predetermined distance from the subject's current location when the subject's visual acuity is below a predetermined threshold.

8. The program according to any one of claims 1 to 3, which causes the processor to output a comparison result between a first contact lens currently being used by the subject and a second contact lens different from the first contact lens, when the subject's visual acuity is below a predetermined threshold.

9. A visual acuity estimation device comprising: a display control unit that causes a subject to display an object that the subject is looking at on a display unit; and an estimation unit that estimates the subject's visual acuity based on the subject's eye movements as the subject follows the object with their eyes.

10. A visual acuity estimation system comprising: a display control unit that displays an object viewed by a subject on a display unit; and an estimation unit that estimates the subject's visual acuity based on the subject's eye movements as they follow the object with their eyes.

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