Testing and determining a threshold value

Abstract

This invention relates to testing and determining a threshold value used in psychometric testing in field of ophthalmology, neuro-ophthalmology and visual neuropsychology. The method comprises at least the following steps: a) displaying a symbol with a distinctive visual appearance and with a stimulus level to a display at a stimulus time-point, the symbol selected from a group of possible symbols, b) monitoring if a response is given on a response device with multiple choices, each choice representing a possible visual appearance or location of the symbol, and b1) if a response is not given in a response time-limit from the stimulus time-point, increasing the stimulus level of the symbol by a predetermined step and returning to step a), or b2) if a response is given in the response time-limit from the stimulus time-point, comparing the response to symbol displayed in step a), and c1) if the response does not correspond to the symbol displayed in step a), producing, e.g. displaying, an error feedback and returning to step a), or c2) if the response corresponds to the symbol displayed in step a), determining if stop criteria for the test is satisfied, and d1) if stop criteria for the test is not satisfied, decreasing the stimulus level by a predetermined step and returning to step a), or d2) if stop criteria for the test is satisfied, ending the test.

Claims

1. Method for testing and determining a threshold value in psychometric testing in field of ophthalmology, neuro-ophthalmology and visual neuropsychology, the method comprising at least the following steps: a) displaying a symbol (102) with a distinctive visual appearance and with a stimulus level to a display (101) at a stimulus time-point, the symbol having been selected from a group of possible symbols, b) monitoring if a response is given on a response device (103) with multiple choices (104, 105), each choice representing a possible visual appearance or location of the symbol, and b1) if a response is not given in a response time-limit from the stimulus time-point, increasing the stimulus level of the symbol by a predetermined step and returning to step a), or b2) if a response is given in the response time-limit from the stimulus time-point, comparing the response to symbol (102) displayed in step a), and c1) if the response does not correspond to the symbol displayed in step a), producing an error feedback and returning to step a) to display a new symbol having the same stimulus level as the previous symbol, d1) if stop criteria for the test is not satisfied, decreasing the stimulus level by a predetermined step and returning to step a), or d2) if stop criteria for the test is satisfied, ending the test.

2. Method according to claim 1, wherein said response time-limit is more than 0.5 seconds but less than 3 seconds.

3. Method according to claim 1, wherein said group of possible symbols comprises only two possible symbols.

4. Method according to claim 1, wherein said stimulus level of the symbol is the size of the symbol.

5. Method according to claim 1, wherein said stimulus level of the symbol is the contrast level of the symbol on the display.

6. Method according to claim 1, wherein if a response is not given in a response time-limit and the previous response corresponded to the displayed symbol, or if the response corresponds to the symbol displayed and the previous response was not given in a response time-limit, then the predetermined step by which the stimulus level of the symbol is changed is decreased from its previous value.

7. Method according to claim 1, wherein, if for a number of times in a row, a response is not given in the response time-limit from the stimulus time-point, or the response corresponds to the symbol displayed in step a), then the predetermined amount by which the stimulus level of the symbols are changed is increased.

8. The method of claim 1, wherein said error feedback is a member of the group consisting of a visual message, an audible error sound and a vibration message.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) The invention is described in more detail below with reference to the enclosed schematic drawing, in which

(2) FIG. 1 shows a medical device according to the invention from the first side of the perimeter surface in a first situation,

(3) FIG. 2 shows the medical device of FIG. 1 from the second side of the perimeter surface,

(4) FIG. 3 shows a medical device according to the invention from the first side of the perimeter surface in a first second situation,

(5) FIG. 4 shows the medical device of FIG. 3 from the second side of the perimeter surface,

(6) FIG. 5 shows a medical device according to the invention from the first side of the perimeter surface in a third situation,

(7) FIG. 6 shows the medical device of FIG. 5 from the second side of the perimeter surface,

(8) FIG. 7 shows a flow chart of a method according to the invention,

(9) FIG. 8 shows an apparatus according to the invention,

(10) FIGS. 9a to 9f show some symbols, such as an optotypes, patterns or tasks according to the invention.

DETAILED DESCRIPTION OF THE EXAMPLES OF THE FIGURES

(11) For the sake of clarity, the same reference numbers are used for corresponding parts in different embodiments.

(12) FIGS. 1 to 6 show a stand-alone medical device 1 for testing a patient according to the invention. The device 1 comprises a first testing device, i.e. a perimeter surface 2. The perimeter surface has a first side 3 to be viewed by the patient during testing and second side 4 not to be seen by the patient during testing. A display unit 5 is arranged turnable with hinge 6 below the perimeter surface. The display unit comprises a touchscreen display 7, which functions both as a user interface device and as a display to be viewed by the patient during testing of so called second tests. A computer controlling the use of the medical device is integrated inside the display unit 5 or the perimeter surface 2. The second tests, which are at least partly shown on the display 7, may comprise e.g. visual acuity measurement, contrast sensitivity testing or glare testing.

(13) The display unit 5 is arranged turnable between at least two positions, i.e. the first position (see FIG. 3) and the second position (see FIG. 1). For transport and storage, it is possible that the display unit 5 is further turned into a transport position (see FIG. 5), but this may be the same position as e.g. the first position. In the first position the display 7 can be viewed from the first side 3 of the perimeter surface, i.e. by the patient to be tested. In the second position the display 7 can be viewed from the second side 4 of the perimeter surface, e.g. by the person supervising the test. The display unit 5 may be kept in the second position e.g. when performing a test with the first testing device, i.e. with the perimeter surface 2. This way the person supervising the test may supervise and control the test with the user interface in the display unit 5.

(14) The perimeter surface 2 is arranged foldable around hinges 8 between at least two positions, i.e. a use position (FIG. 1) and a transport position (FIG. 5). In the use position the perimeter surface 2 is arranged open and the first side 3 of the perimeter surface 2 may be viewed by the patient. In transport position the perimeter surface 3 is folded so that side parts 9 of the first side 3 of the perimeter surface are not viewable by the patient.

(15) A handle 10 is situated near the top of the second side 4 of the perimeter surface 2. A turnable support leg 11 allows the device to be kept in a suitable position e.g. on a table. The support leg 11 may be turned between at least two positions, the use position (FIG. 1) and the transport position (FIG. 5). Batteries are situated in stationary legs 12, behind lids 13. The movement of the turnable support leg 11 may be controlled with clamping screws 14. Ambient light sensors 15 are arranged in the device to detect lighting conditions around the device 1 and to monitor and/or adjust the performance of the first and/or second testing devices 2, 3. Proximity sensors 16 are arranged in the device to detect the position of the patient. Glare lights 17 to be lighted towards the patient during testing of glare are situated near the display unit 5. Buttons 18 may be used by the patient in some tests, e.g. to indicate if a visual stimulus was seen.

(16) The first testing device comprises at least one light matrix 19, such as a LED matrix or an OLED matrix or an LCD matrix, capable of displaying perimeter stimulus and/or fixation objects at least to the first side of the perimeter surface. The positions 19 of the matrix lights shown in FIG. 1 are only exemplary, the positions of the lights in the light matrix may be selected in various ways. The first side 3 of the perimeter surface 2 is covered with a translucent layer 20, which hides the light matrix 19 from the patient when the light matrix is not lighted. But when a light in the light matrix is lighted, the light is seen through the translucent layer 20.

(17) The perimeter surface 2 comprises several small light openings 21 towards its second side 4. The openings 21 are situated at the positions where the lights, e.g. LEDs of the light matrix 19 are situated on the first side 3 of the perimeter surface 2. This way the person supervising the test from the second side 4 of the perimeter surface 2 can see where the fixation object or visual stimulus is lighted.

(18) A power on/off-switch 22 and I/O-sockets 23 are situated on the second side 4 of the perimeter surface 2.

(19) FIG. 7 shows a flow chart of one possible method and computer program of the invention. In step 201 the method is started. In step 202 a symbol with a distinctive visual appearance and with a stimulus level is displayed to a display. In step 203 a response device is monitored. If a response is not given in a response time-limit the stimulus level of the symbol is increased by a predetermined step in step 204 and the program is returned to step 202. On the other hand, if a response is given in the response time-limit the program continues to step 205. In step 205 the response from step 203 is compared to the symbol displayed in step 202. If the response does not correspond to the symbol displayed an error feedback is displayed in step 206 and the program is returned to 202 for displaying of a new symbol with the same stimulus level as with the previous symbol. On the other hand, if in step 205 the response from step 203 corresponds to the symbol displayed in step 202 the program proceeds to step 207 for determining if stop criteria for the test is satisfied. If stop criteria for the test is not satisfied, the stimulus level is decreased by a predetermined step in step 208 and the program is returned to step 202. On the other hand, if in step 207 stop criteria is satisfied, program terminates in step 209.

(20) FIG. 8 shows an apparatus for testing and determining a threshold value in visual acuity, contrast sensitivity, color vision deficiency or glare sensitivity. The apparatus 100 comprises a display 101 for displaying a symbol 102 and a response device 103 with two choice actuators, i.e. buttons 104 and 105. Each button represents a possible visual appearance of the symbol 102, in this case orientation of the symbol either to the left or to the right.

(21) In FIG. 8 a patient or test subject 110 watches the display 101, such as a tablet computer screen. When he/she identifies in which way the Landolt-C symbol 102 is oriented, he/she makes a decision to press the button which corresponds to that orientation. In the example the symbol 102 is oriented to the right and the test subject 106 is about to press the corresponding button 105 with an arrow to the right.

(22) A computer program runs on the memory 106 of computer 107. The program sends instructions to the display 101 via electronic data communication link 108 on which symbols 102 to display. The computer 107 also receives, via another data communication link 109, knowledge from response device 103, such as a mobile phone application, of which button 104 or 105 is pressed and at which time-point.

(23) The button 105 in FIG. 8 is the correct one and if it is pressed before time-out, a correct response is recorded in the memory 106 of the computer 107 of the apparatus.

(24) FIGS. 9a to 9f show some examples of symbols, such as an optotypes, patterns or tasks according to the invention displayed on a display 101. FIG. 9a shows a traditional tumbling E, and the task for the test subject could be e.g. Which direction are the fingers of the E pointing to? The right answer would be: Left.

(25) FIG. 9b shows two different patterns, vertical and diagonal stripes, on different sides of the display 101. The task for the test subject could be e.g. On which side (left or right) the stripes are vertical? The right answer would be: Left.

(26) FIG. 9c shows two different symbols, a square and a circle, on different sides of the display 101. The task for the test subject could be e.g. On which side (left or right) there is a square? The right answer would be: Left.

(27) FIG. 9d shows a gray Landolt C on a white background of display 101. The task for the test subject could be e.g. Which direction is the gap of the C pointing to? The right answer would be: Right.

(28) FIG. 9e shows a gray Landolt C on a lighter grey background of display 101. The task for the test subject could be e.g. Which direction is the gap of the C pointing to? The right answer would be: Right. The background and the symbol on the foreground could also be of different colors.

(29) FIG. 9f shows a gray dot on a lighter grey background of display 101. The task for the test subject could be e.g. On which side (left or right) there is a dot? The right answer would be: Right.

(30) The figures show only a few preferred embodiments. Facts of secondary importance with regards to the main idea of the invention, facts known as such or evident for a person skilled in the art, such as power sources or support structures possibly required by the invention, are not necessarily separately shown in the figures. It is apparent to a person skilled in the art that the invention is not limited exclusively to the examples described above, but that the invention can vary within the scope of the claims presented below. The dependent claims present some possible embodiments of the invention, and they are not to be considered to restrict the scope of protection of the invention as such.