CN105942965A - Subjective vision self-testing device based on intelligent terminal - Google Patents

Abstract

The invention discloses a subjective visual acuity self-test device based on an intelligent terminal. The device includes: a visual acuity grade selection unit, an optotype display unit, and a response information receiving unit; wherein, the visual acuity grade selection unit is used for selecting a visual acuity grade in the self-test process; Select the optotype corresponding to the test visual acuity level, and display the optotype in a random direction through the display device of the smart terminal; the response information receiving unit is used to receive the response information of the subject for the currently displayed optotype and respond The information is transmitted to the vision class selection unit. The invention also discloses a subjective visual acuity self-test system. The present invention can utilize the intelligent terminal widely used at present to realize the subjective visual acuity self-test, and has higher detection precision, larger detection range and shorter detection time.

Description

A subjective visual acuity self-test device based on an intelligent terminal

technical field

The invention relates to a visual acuity measuring device, in particular to a subjective visual acuity self-testing device based on an intelligent terminal.

Background technique

Visual acuity testing is divided into subjective visual acuity testing and objective visual acuity testing. Among them, medical optometry belongs to objective visual acuity testing, while subjective visual acuity testing mainly uses the visual acuity chart to detect visual acuity. Subjective visual acuity is also called visual acuity chart.

In 1862, Snellen first created the eye chart at the Second International Ophthalmology Congress held in Paris, and proposed a form for testing eyesight composed of letters with similar stroke thickness, that is, the letter eye chart. Since then, various eye charts have been proposed. Among them, the eye chart commonly used by people before is the "International Standard Eye Chart" drawn by Professor Sun Jizhong under the guidance of Professor Zhou Chenghu in 1952. Later, Miao Tianrong designed the "Standard Logarithmic Vision Chart" in 1958, which is still in use today. The reason why the "Standard Logarithmic Vision Chart" is very popular is that it can directly use the difference in visual acuity grades to represent the real poor visual acuity, and the higher the visual acuity grade, the better the vision, and the lower the visual acuity grade, the worse the vision. In line with people's measurement habits.

The traditional method of visual acuity measurement requires the guidance of medical personnel. Starting from the large visual target, the subject is required to point out the direction of the visual target. If it is correct, point to a smaller visual target until reaching the smallest visual target that can be seen clearly. Such a measurement method greatly increases the burden on the medical staff, and is time-consuming and labor-intensive; in addition, the optotypes on the eye chart are fixed, and the number of optotypes in a line with large optotypes is too small, only 1 to 3 optotypes, which are easy to remember. Moreover, it is difficult to evaluate the vision changes of patients with eye diseases that significantly affect vision; the number of visual targets in each row is different, which affects the sensitivity and specificity of the measurement results; in addition, the distance between visual targets in each row is uncertain, and the crowding effect is inconsistent, which affects the diagnosis of vulnerable children and curative effect observation.

In order to overcome the shortcomings of traditional subjective vision testing methods, some researchers have also proposed the use of intelligent terminals for subjective vision testing. However, these existing solutions generally have the problems of low detection accuracy and long detection time.

Contents of the invention

The technical problem to be solved by the present invention is to overcome the deficiencies in the prior art and provide a subjective visual acuity self-test device based on an intelligent terminal, which can realize subjective visual acuity self-test by using the intelligent terminal widely used at present, and the detection accuracy is higher, and the detection range Larger and shorter detection times.

The present invention specifically adopts the following technical solutions to solve the above technical problems:

A kind of subjective visual acuity self-test device based on intelligent terminal, described subjective visual acuity self-test device comprises:

The visual acuity level selection unit is used to select the visual acuity level, and the visual acuity level is divided by the five-point recording method, and the difference between adjacent visual acuity levels is 0.01; the visual acuity level selection method is as follows: the upper and lower limits of the measurement range of the self-test device Take the maximum visual acuity level and the minimum visual acuity level respectively, and use the intermediate visual acuity level of the maximum visual acuity level and the minimum visual acuity level as the test visual acuity level of the first round of testing, and judge whether the tested person can reach the current round of visual acuity level according to the response information of the testee. Test vision level, if yes, take the test vision level of this round as the minimum vision level of the next round of testing; if not, use the test vision level of this round as the maximum vision level of the next round of testing; The intermediate visual acuity level between the current maximum visual acuity level and the minimum visual acuity level is used as the test visual acuity level of the current round. According to the response information of the testee, it is judged whether the testee can reach the test visual acuity level of the current round. The visual acuity level is used as the minimum visual acuity level of the next round of testing; if not, the test visual acuity level of this round is used as the maximum visual acuity level of the next round of testing; The visual acuity level of the test round, and the visual acuity level of the current round is adjacent to the current maximum visual acuity level, then the visual acuity level of the current round is used as the testee’s final subjective visual acuity self-test result output;

An optotype display unit, configured to generate an optotype corresponding to the test vision level currently selected by the vision level selection unit, and display the optotype in a random direction through the display device of the smart terminal;

The response information receiving unit is used for receiving the response information of the subject to the currently displayed optotype and transmitting the response information to the vision level selection unit.

In order to avoid the influence of the space limitation during the test on the test result, preferably, the visual mark display unit includes:

The test distance setting module is used to set the test distance between the person under test and the display device of the smart terminal;

The optotype generation module calculates the size of the optotype corresponding to the test vision level currently selected by the vision level selection unit in real time according to the set test distance, and generates an optotype of a corresponding size.

In order to avoid the difference in display resolution of the smart terminal used from affecting the test results, further, the visual mark display unit also includes:

The optotype correction module is used to collect the resolution of the display device of the smart terminal, and correct the size of the optotype generated by the optotype generation module according to the collected resolution.

Preferably, the response information receiving unit is realized by a human-computer interaction unit of the smart terminal, or by an auxiliary smart terminal capable of communicating with the smart terminal.

Compared with the prior art, the present invention has the following beneficial effects:

The present invention utilizes the intelligent terminal to realize autonomous subjective visual acuity detection, which is not limited by time and place, and is convenient to use; the present invention can effectively evaluate the power changes of amblyopic people; The defects of the inconsistent crowding effect of the traditional eye charts; the random generation of the optotypes effectively avoids the inaccurate measurement caused by the direction of some optotypes being recorded in advance in the traditional eye charts.

The visual acuity measurement range of the invention is larger than that of the traditional visual acuity chart, and the detection accuracy is an order of magnitude higher than that of the traditional visual acuity chart. At the same time, the time for completing a self-test is greatly reduced due to the adoption of the visual acuity level selection method using the binary search algorithm.

Description of drawings

Figure 1 is a schematic diagram of the design principle of the visual mark;

Fig. 2 is the algorithm flow chart that visual acuity grade is selected;

Fig. 3 is to carry out the detection efficiency contrast of visual acuity detection with subjective visual acuity self-test device of the present invention and traditional method respectively;

Fig. 4 is to carry out the detection result comparison of visual acuity detection with subjective visual acuity self-test device of the present invention and traditional method respectively;

Fig. 5 is the detection result of multiple visual acuity tests with the subjective visual acuity self-test device of the present invention.

detailed description

The technical scheme of the present invention is described in detail below in conjunction with accompanying drawing:

In order to solve the shortcomings of the existing technology, the present invention proposes a subjective visual acuity self-test device based on an intelligent terminal by using the intelligent terminal widely used at present, relying on the computing capability and display capability of intelligent terminals such as personal computers, notebook computers, and intelligent TVs. and interaction ability, combined with the subjective visual acuity self-test device of the present invention, can realize subjective visual acuity self-test with higher precision, larger range, and higher efficiency without the assistance of others.

The subjective visual acuity self-testing device of the present invention comprises: a visual acuity level selection unit, an optotype display unit, and a response information receiving unit.

Wherein, the eyesight level selection unit is used to select the eyesight level in the self-test process; the visual mark display unit is used to generate the visual mark corresponding to the test eyesight level currently selected by the eyesight level selection unit, and through the display device of the intelligent terminal The optotype is displayed in a random direction; the response information receiving unit is used to receive the response information of the subject to the currently displayed optotype and transmit the response information to the vision level selection unit.

The visual acuity detection range in the prior art is usually 4.0-5.2 (five-point recording method), and the minimum precision is 0.1. On the one hand, the measurement results are not accurate enough; on the other hand, the eyesight of some people is likely to exceed the above detection range. For this reason, the present invention extends the measurable range to 3.60-5.50 (five-point recording method), and the detection accuracy is 0.01, that is, the difference between adjacent vision levels is 0.01. To this end, need to redesign the corresponding optotype. In the technical solution of the present invention, the visual target display unit calculates the size of the visual target according to the principle of viewing angle and displays it through the display of the intelligent terminal, and only one visual target is displayed at a time. The present invention can adopt various existing optotypes, such as the most commonly used E-shaped optotypes, Landlot circular optotypes, and the like. Taking the E-shaped optotype commonly used in my country as an example, the entire E-shaped optotype occupies a 5*5 square, in which the size of the gap is equal to the thickness of a stroke, and the side length of the E-shaped optotype is 5 times the size of the gap. As shown in Figure 1, assume that the viewing angle is α (unit: minute), the detection distance is D (unit: mm), the vision value is V (decimal recording method), and the gap size of the visual mark is Gap (unit: mm), then According to the principle of viewing angle, the empirical formula can be obtained: Wherein the viewing angle α=1/V. The size of the E-shaped optotype of the corresponding vision grade can be calculated according to the visual acuity value V. Assuming that the vision value under the five-point recording method is k, the conversion formula between the five-point recording method and the decimal recording method is: therefore, The size calculation of other shape optotypes is similar to this. The optotype display unit can generate corresponding optotypes according to the above method and display them on the display screen of the smart terminal. In order to further avoid the impact of the space limitation during the test on the test results, and avoid the impact of the difference in the display resolution of the smart terminal used on the test results, the present invention can also set the test distance and correct the size of the visual target according to the resolution of the display. Specifically, the optotype display unit includes:

The test distance setting module is used to set the test distance between the person under test and the display device of the smart terminal;

The optotype generation module calculates the size of the optotype corresponding to the currently selected test vision level of the vision level selection unit in real time according to the set test distance, and generates an optotype of the corresponding size;

The optotype correction module is used to collect the resolution of the display device of the smart terminal, and correct the size of the optotype generated by the optotype generation module according to the collected resolution.

When the visual acuity value is 1.0 (that is, 5.0 of the five-point recording method) and the measurement distance is 5m, the gap size of the E-shaped visual target is calculated by applying the formula:

The size of the whole E-shaped visual mark is: font size=5*1.454=7.270mm. On a standard computer with a screen size of 17 inches and a resolution of 1024*768, the physical length of each pixel is 0.29mm, that is, the gap pixels of the E-shaped visual mark displayed on the computer screen are: 1.454/0.29=5.01 pixels, It can be seen that the standard computer screen can clearly display the visual target.

The visual acuity measurement range of the present invention is larger than that of the prior art, and the measurement accuracy is also higher than that of the prior art by an order of magnitude, which also results in the number of visual targets required for visual acuity detection being far greater than that of conventional eye charts. In the detection process where the grades change step by step, many rounds of measurements and a long time are required to determine the true vision of the subject. Therefore, it is necessary to redesign the change process of the visual acuity level in the self-test process. The process of gradually approaching the real visual acuity value in the vision detection process can be regarded as an ordered search in the data search, and the available ordered search methods are: sequential search method, binary search method, and binary sorting tree search method. The search times are shown in Table 1.

Table 1 Comparison of search times of three search algorithms

By comparing the available search algorithms, it is found that the binary search method is the most suitable, so the present invention uses the binary search method to select and adjust the visual acuity level. The visual acuity level selection method adopted by the visual acuity level selection unit is as follows: the upper and lower limits of the measurement range of the self-test device are used as the maximum visual acuity level and the minimum visual acuity level respectively, and the intermediate visual acuity level between the maximum visual acuity level and the minimum visual acuity level is used as the first round. The test vision level of the test, and judge whether the testee can reach the test vision level of the current round according to the response information of the testee, if yes, use the test vision level of the current round as the minimum vision level of the next round of testing; if not , then the test vision level of the current round is used as the maximum vision level of the next round of testing; the second round of testing uses the intermediate vision level between the current maximum vision level and the minimum vision level as the test vision level of the current round, according to the testee's Respond to the information to judge whether the testee can reach the test vision level of the current round, if yes, use the test vision level of the current round as the minimum vision level of the next test; if not, use the test vision level of the current round as the next test The maximum visual acuity level of the round test; and so on, until in a certain round of testing, the testee can reach the test visual acuity level of the current round, and the test visual acuity level of the current round is adjacent to the current maximum visual acuity level, then the current round of visual acuity level is used The visual acuity level of the test is output as the final subjective visual acuity self-test result of the subject.

The function of the response information receiving unit is to receive the response information of the subject to the currently displayed optotype and send the response information to the vision level selection unit to judge whether the subject correctly recognizes the currently displayed optotype. There are many specific ways to implement the response information receiving unit, for example, it can be realized through the human-computer interaction unit (keyboard, remote control, touch panel, voice recognition unit, etc.) of the intelligent terminal; Auxiliary smart terminals are implemented, such as the most common smart phones.

In order to facilitate the public's understanding, the technical solution of the present invention will be further described in detail below with a specific embodiment.

The subjective vision self-test device in this embodiment is based on a personal computer (as an intelligent terminal) and a smart phone (as an auxiliary intelligent terminal). Users need to download and run the self-test system program on the personal computer, and install the self-test system APP on the mobile phone. First, after the user sets up the personal computer according to the requirements, the personal computer will bind the port number entered by the user and open a new thread, which is used to monitor the messages sent by the smart phone and parse the messages sent by the smart phone into a string; The smartphone can send messages to the PC through the PC's IP address and port number. According to the direction of the visual target displayed on the computer screen, the user presses the corresponding direction key on the smart phone (if you cannot distinguish the direction of the visual target on the computer screen, you can press the "skip" button), then the smart phone will have a direction The data packet of the message is sent to the personal computer, and the personal computer determines the next visual mark displayed on the computer screen through the vision level selection unit and the visual mark display unit after receiving the message. Finally, the visual acuity level selection unit calculates the visual acuity value of the testee and feeds back the visual acuity value to the smart phone and displays it on the screen of the mobile phone. So far, the testee completes the first visual acuity test. The PC keeps the port listening, ready for the user's next measurement.

In this embodiment, the system adopts an E-shaped visual mark, the visual acuity measurement range is 3.60-5.50 (five-point recording method), and the detection accuracy is 0.01. The visual acuity grade selection algorithm realization of visual acuity grade selection unit is as shown in Figure 2, starts to be recorded as start from minimum visual acuity grade 360, and is recorded as end to maximum visual acuity grade 550, gets the visual acuity grade that is positioned at both intermediate values, i.e. mid=(start +end)/2 for the first test. Under this level of vision, if there are 3 correct answers out of 5 times (in Figure 2, k is the number of display times of visual targets corresponding to each vision level, and i is the number of correct answers to the direction of visual targets in each vision level test), then start = mid for the second measurement; if you get 3 wrong answers out of 5 times or press the "skip" button because you can't see clearly, then take end=mid for the second measurement...and so on until you can see Clear the minimum visual acuity, or until the visual acuity level reaches 550, or the side length of the visual acuity is 5 pixels, record the mid value at this time is also level, then level/100 is the final measured visual acuity value. The visual acuity level selection unit displays the visual acuity measurement result in two ways of five-point recording method and decimal recording method and sends the visual acuity measurement result to the smart phone.

There are four direction buttons set in the APP interface of the self-test system on the smart phone. When the subject can fully identify the direction of the visual target, he will press the button correctly. When the subject cannot recognize the direction of the visual target, it will randomly Press any arrow key. In the testing process, there are four orientations of the E-shaped visual target. Assuming that the testee can completely see the visual target, the probability of answering the correct orientation of the visual target is 100%. When it is purely "guessing", the probability of correctly answering the direction of the visual target is 25%. Combining the above two situations, it is considered that the probability of the subject's normal answer to the correct direction of the visual target is the average probability of these two situations: (100%+25%) /2=62.5%, that is, if the test is performed 5 times under the same vision level, as long as the correct answer is 5×62.5%≈3 times, it is considered that the subject can see the visual mark of this level clearly.

In this embodiment, the software on the personal computer uses a graphical interface designed by Eclipse. The system automatically obtains the IP address of the machine and displays it on the interface, eliminating the need for users to find the IP address of the machine themselves. In addition, the user needs to fill in the port number, which is any integer between 1 and 65535, and drag the slider on the screen to measure the physical distance of 5cm with a ruler, which can ensure that different resolutions and sizes The corresponding size of the visual mark is accurately displayed on the computer. Because the physical size displayed by the picture on the computer is related to the computer screen resolution and size, and different computer screen resolutions and sizes are different, in order to facilitate the acquisition of the user's computer resolution, the present invention designs such a slide bar. The length of the entire slider is 320pixels. The system can obtain the percentage of the position of the slider in the entire slider, which is recorded as x%, and the physical length of this distance measured by a ruler is 5cm, which can be easily calculated on the computer screen. Centimeters are: (3.2x/5)pixel. Users can also choose the measurement length according to their own conditions, and click the "Complete Setting" button after the setting is completed. If the user does not fill in the port number, or fills in an illegal port number, or does not drag the 5cm distance, or does not select the test distance, the system will give a corresponding prompt.

In order to prove the feasibility of the present invention, the above-mentioned subjective visual acuity self-assessment system was used to carry out multiple tests, and finally 30 effective data of measurement were selected for analysis, as shown in Table 2. The experimental conditions are as follows: the measurement distance is selected as 3 meters, the measurement process follows the detection order of the right eye first and then the left eye, and the ambient light and internal illuminance remain unchanged in the process of using the traditional vision detection method and the self-test system detection method, and each When the volunteers tested their eyesight, they kept the detection status consistent.

Table 2 Visual acuity values using traditional test methods and subjective visual acuity self-assessment system test methods

Fig. 3 shows a line comparison chart of the detection times of 30 eyes respectively using the traditional method detection method and the self-test system detection method during the test process. Among them, using the traditional method of detection, the number of measurements is related to the final visual acuity value. The better the vision, the more the number of measurements, and the worse the vision, the less the number of measurements, so the floating range is large. When the visual acuity is normal, that is, when the visual acuity is 5.0, the number of measurements is 14 times. However, the number of detections required by the present invention is constant and does not change with the visual acuity of the testee. Calculate the average number of times that 30 eyes use the traditional visual acuity detection method to measure: 6.6 times, and use the self-test system of the present invention to measure the number of times on average to be 7 times, because of using "binary search method" to find the number of times fixed, the number of searches=log ₂ N= log ₂ (550-360)≈7 times. Because the traditional visual acuity test method has a difference of only 0.1 in each visual acuity level, but the invented self-assessment system has a difference of 0.01 in each visual acuity level, and their average measurement times are basically equal. If the self-test system of the present invention also uses the sequential search method to detect, when the subject's visual acuity value is 5.0, the number of times of detection is: (5.00-3.60)*100=140 times. Such number of times of detection seriously affects detection efficiency, therefore, the eyesight level selection method designed by the present invention——binary search method makes search efficiency greatly improved, can reduce number of times of search from 140 times to 7 times, rapidity is good, and detection efficiency is extremely high high.

Figure 4 is a comparison chart of the visual acuity values measured by the traditional visual acuity testing method and the subjective visual acuity self-testing system for 30 eyes respectively. measurement accuracy. It shows that using this system to measure visual acuity can obtain very accurate measurement results under the condition of ensuring the autonomy and rapidity of measurement, and it can also monitor the changes of patients' visual acuity more accurately in clinical practice.

Fig. 5 is to select 4 volunteers to use the self-assessment system of the present invention to measure the visual acuity of their left and right eyes repeatedly 3 times, record the measurement results for three times, and the different stripes in the histogram respectively represent the measurement results for three consecutive times. It can be seen from the figure that the three measurement results of each eye are basically consistent, indicating that the visual acuity test results obtained by using the self-test system of the present invention have good stability.

Claims (6)

1. a Subjective visual acuity self-measuring device based on intelligent terminal, it is characterised in that described Subjective visual acuity self-measuring device includes:

The difference of the inter-stages such as vision Level selection unit, is used for selecting vision grade, described vision grade to use five member record methods to divide, adjacent vision is 0.01；Vision hierarchical selection method is specific as follows: measure the upper and lower limit of scope as maximum vision grade, minimum vision grade using self-measuring device, the test vision grade tested as the first round using the intermediate vision grade of maximum vision grade with minimum vision grade, and judge whether measured can reach the test vision grade of epicycle according to the response message of measured, in this way, then the minimum vision grade tested using the test vision grade of epicycle as next round；As no, then the maximum vision grade tested using the test vision grade of epicycle as next round；Second takes turns the test vision grade tested using the intermediate vision grade of current maximum vision grade and minimum vision grade as epicycle, response message according to measured judges whether measured can reach the test vision grade of epicycle, in this way, then the minimum vision grade tested using the test vision grade of epicycle as next round；As no, then the maximum vision grade tested using the test vision grade of epicycle as next round；The rest may be inferred, take turns in detection until a certain, measured can reach the test vision grade of epicycle, and the test vision grade of epicycle is adjacent with current maximum vision grade, then using the test vision grade of epicycle as the Subjective visual acuity that measured is final test oneself result output；

Sighting target display unit, for generating the sighting target that test vision grade currently selected with vision Level selection unit is corresponding, and shows described sighting target by the display device of described intelligent terminal according to random direction；

Response message receive unit, for receive measured for the response message of currently displayed sighting target and by response message transmit to vision Level selection unit.

2. Subjective visual acuity self-measuring device based on intelligent terminal as claimed in claim 1, it is characterised in that described sighting target display unit includes:

Measuring distance arranges module, for arranging the measuring distance between measured and the display device of intelligent terminal；

Sighting target generation module, calculates, according to set measuring distance, the sighting target size that test vision grade currently selected with vision Level selection unit is corresponding in real time, and generates correspondingly sized sighting target.

3. Subjective visual acuity self-measuring device based on intelligent terminal as claimed in claim 2, it is characterised in that described sighting target display unit also includes:

Sighting target correction module, for gathering the resolution of the display device of described intelligent terminal, and the sighting target size generated sighting target generation module according to the resolution gathered is corrected.

4. Subjective visual acuity self-measuring device based on intelligent terminal as described in any one of claims 1 to 3, it is characterized in that, described response message is received unit and is realized by the man-machine interaction unit of described intelligent terminal, or by can and described intelligent terminal between the auxiliary intelligent terminal that communicates realize.

5. a Subjective visual acuity self-measuring system, it is characterised in that include intelligent terminal and as described in any one of claims 1 to 3 Subjective visual acuity self-measuring device based on intelligent terminal.

6. as claimed in claim 5 Subjective visual acuity self-measuring system, it is characterised in that also include can and described intelligent terminal between the auxiliary intelligent terminal that communicates；Described response message is received unit and is realized by auxiliary intelligent terminal.