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    • 专利摘要:
    Method and system to measure the dynamics of recovery of mesopic contrast sensitivity. A method and implementation system is presented that simultaneously reports the functioning of both the external and internal retina quickly. It comprises the brief dazzle of a subject's eye with a light source to produce a transient contrast insensitivity and to measure the contrast and the time at which the subject detects successive visual stimuli modulated in its contrast and presented psychophysically for a time in an automated way. on a background of mesopic luminance. The responses that the subject provides during the recovery of contrast sensitivity mediated by the cones of the retina are recorded to obtain characterizing parameters of this recovery dynamics and compare them with a normative database to detect alterations in visual function typical of diseases neurodegenerative of the retina. (Machine-translation by Google Translate, not legally binding)
    公开号:ES2785082A1
    申请号:ES202030311
    申请日:2020-04-17
    公开日:2020-10-05
    发明作者:Marín María Cinta Puell
    申请人:Universidad Complutense de Madrid；
    IPC主号:
    专利说明:

    [0002] Method and system to measure the dynamics of recovery of mesopic contrast sensitivity
    [0004] TECHNICAL SECTOR
    [0005] The present invention falls within the field of methods and apparatus for examining the eyes and more specifically that of methods and systems that require the active assistance of the patient.
    [0007] BACKGROUND OF THE INVENTION
    [0008] The human retina is made up of several layers of interconnected neurons. The outer retina contains cells sensitive to light or photoreceptors (rods and cones) and their distribution varies throughout the retina, with the density of cones being higher in the central area (macula) and the density of rods higher in the perimacular area. . Cones work in photopic (high light) conditions and rods work in scotopic (dark) conditions whose intensity is insufficient for vision to be driven by the cones. Under mesopic conditions (0.01 - 5 cd / m2), both photoreceptors can be activated with different levels of involvement. On the other hand, the inner retina contains the neurons or ganglion cells that are responsible for the mechanism that processes the contrast of the image that is formed in the retina from objects of different sizes or spatial frequencies.
    [0010] Contrast sensitivity is the eye's ability to perceive differences between an object and its background. The minimum amount of contrast that is necessary to detect or distinguish an object from its background is known as the contrast threshold, and its inverse is the contrast sensitivity (generally expressed in logarithmic units). Sensitivity to spatial contrast is usually measured using sine wave gratings (light and dark fringes) as stimuli that can vary in their width or spatial frequency (cycles per degree of visual angle) as well as their contrast.
    [0012] The sensitivity to spatial contrast for viewing objects of different contrast and different spatial scale depends both on the characteristics of the eye and on neural processing. Thus, a decrease or alteration in sensitivity to Contrast for viewing small objects (high spatial frequency) at photopic light levels is generally due to the characteristics of the optical system (such as refractive errors of the eye) while alterations in contrast sensitivity observed in mesopic conditions are attributed to neuronal factors where ganglion cells are those that are involved. (Spear PD. Neural bases of visual deficits during aging. Vision Res. 1993; 33: 2589-3609).
    [0014] One of the factors that influence contrast sensitivity is age. Thus, one of the most common observations made by older adults, even those without eye disease and good visual acuity, is the problem to see in low light conditions (especially problems with night driving when the driver tries to identify objects of low contrast such as unlit obstacles or pedestrians). With aging there is also a greater decrease in contrast sensitivity mesopic compared to photopic.
    [0016] Another important factor that influences contrast sensitivity is the presence of some neurodegenerative disease of the retina. In glaucoma (ganglion cell disease), contrast sensitivity is decreased. A decrease in sensitivity to mesopic contrast has also been observed in age-related macular degeneration (AMD).
    [0018] Under normal conditions, when the eye suffers a temporary glare from having been exposed to a very bright light source, a temporary numbness or blurring of vision occurs. The recovery of sensitivity depends, and therefore on the return of vision as well, on the rate of regeneration of the visual pigments contained in the photoreceptors. This regeneration depends, in turn, on the health and functioning of the retinal pigment epithelium (RPE), which is altered in pathologies such as DAME and leads to prolonged glare recovery times.
    [0020] For this reason, to measure the time required for the eye to return to its normal level of functioning, the measure of recovery time to glare or photostrue is generally used. To do this, the macula is exposed to a light source intense enough to whiten or break down a significant portion of the visual pigments, and vision recovery time is measured by timing the period of time from the moment the glare-producing light is turned off until the patient regains the visual acuity necessary to read sufficiently visible and sufficiently illuminated high-contrast optotypes.
    [0022] The photo-stress or glare recovery time test measures the time required for the macula to return to its normal level of function. The test involves exposing the macula to a light source strong enough to whiten or break down a significant portion of the visual pigments. Vision is reduced due to the afterimage of the glare source producing a temporary state of retinal numbness that can remain even when the light source has disappeared. Vision recovery time is measured by timing the period of time from the moment the glare-producing light is turned off until the patient regains the visual acuity necessary to re-read high-contrast optotypes, sufficiently visible and sufficiently illuminated. The test is carried out under photopic conditions and therefore the photoreceptors involved are the cones. The best clinical technique is to expose the eye to direct ophthalmoscope light for 30 seconds and measure the time required for acuity to return to within the pre-whitening acuity line. In a healthy eye the recovery time is less than 50 seconds with the mentioned technique. A disadvantage of this test is that it only measures the total recovery time, which under photopic conditions is very fast, but it does not take into account how the recovery capacity of the cones varies throughout that time. Patent US6176581 describes an apparatus for administering a photo-stress test that measures the recovery time of the macula to glare previously described.
    [0024] In conditions of total darkness, the photoreceptors involved in light detection are rods. The dark adaptation test assesses the slow recovery of light sensitivity after exposure of the eye to very intense light causing whitening of visual pigments. The obtained dark adaptation curve shows how each time the subject spends more time in the dark, it can detect weaker points of light and represents how the luminance of the detected stimulus changes as a function of time. In healthy eyes the recovery of sensitivity after almost complete whitening is completed in approximately 30 minutes. In aged eyes it lasts a little longer and in eyes with AMD it can reach 1 hour. The recovery dynamics function is divided into a cone-mediated phase followed by a slower rod-mediated phase. In order to obtain the two phases, it is necessary for the light points to appear outside the macula to stimulate both rods and cones, and it is necessary for the pupil to be dilated. The classic instrument for measuring dark adaptation has been the Goldmann-Weekers. There are other clinical devices on the market but their use is restricted due to limited accessibility, high cost, and the need for experience in handling. WO2005023094A2 describes a method and apparatus for the measurement of rod-mediated dark adaptation. Currently, there is no simple and rapid technique that can be used to measure dark adaptation in the clinic and there is no standard dark adaptation parameters that allow comparison of results between different methods. The problems include: 1) the long duration of the examination, which is very tiring for the patient and limits its clinical usefulness; 2) the need to dilate the pupil; 3) the need for eccentric fixation, 4) the difficulty of the initial phase for whitening to occur in the appropriate amount and in the desired area of the retina, and 5) the subjectivity of the patient's response.
    [0026] As discussed above, there is a need for a method and system that simultaneously reports the dynamic functioning of both the external and internal retina in a quick and easy-to-use way in a clinic for the early detection, monitoring of progression or treatment of the neurodegenerative diseases of the retina of the human eye such as, but not limited to, AMD, glaucoma, and diabetic retinopathy.
    [0028] EXPLANATION OF THE INVENTION
    [0029] The present invention describes an automated method and computerized system that implements said method to measure, psychophysically and under mesopic conditions, the time course of recovery of contrast sensitivity after transient glare of an eye of a subject. The invention makes it possible to identify delays in the speed of recovery of contrast sensitivity mediated by the cones and, therefore, alterations in the rate of regeneration of the visual pigments of the cones. Simultaneously, it allows identifying a worsening of the lower or final mesopic contrast threshold and, therefore, alterations in the contrast mechanism processed by the ganglion cells of the inner retina. Therefore, the present invention makes it possible to detect and differentiate alterations in visual function typical of neurodegenerative diseases of the retina of the human eye that can lead to blindness.
    [0031] Said method of measuring the dynamics of recovery of the mesopic contrast sensitivity of the eye of a subject or patient comprises the following steps:
    [0032] - Temporarily dazzle an eye of the subject to whiten the visual pigments of the retina;
    [0033] - Present for short time intervals successive stimuli of constant size with a detection characteristic and modulated in contrast on a background of mesopic luminance;
    [0034] - Obtain a response to each successive stimulus to determine at each moment the contrast detected due to the recovery of contrast sensitivity mediated by cones by means of a psychophysical method of forced choice;
    [0035] - Increase or decrease the contrast of the successive stimuli by means of an adaptive ladder procedure depending on the response of said subject to each presented stimulus;
    [0036] - Record the contrasts detected and the detection times when the ladder is ascending;
    [0037] - Determine the characterizing parameters of the recovery dynamics of the sensitivity to the mesopic contrast from the analysis of the contrasts and times measured and recorded;
    [0038] - Show the curve of the contrasts detected as a function of time, the characterizing parameters and a quality index of the measurement test. - Compare the data with a normative database
    [0040] Transient glare is carried out by exposing the subject's eye to an intense light source to whiten the retina according to known methods, so that the subject must look directly at the light source in order to whiten the central area of the retina, which is easier to do than others methods where the whitening must occur in a peripheral area of the retina and, therefore, the patient must look eccentrically. To achieve the glare, you can use a flash or other procedures such as adaptation fields with illuminated backgrounds or gaze fixed on a light bulb.
    [0042] Once glare has been achieved, the subject observes stimuli successively one by one at a chosen distance (for example, 1 meter). At the beginning of this measurement stage, the subject does not see the stimuli due to the whitening of the retina, which produces a temporary insensitivity, but as time passes the subject regains sensitivity. The first stimuli that can be detected will have a relatively high contrast (high threshold), but as time passes, the ability to detect stimuli with a lower contrast (lower threshold) increases until the end of the test when the threshold of is reached. final contrast or lower contrast that can be detected and corresponding to higher contrast sensitivity.
    [0044] During the measurement stage, the patient must recognize the orientation of the detection characteristic of targets or figures always of the same size and low spatial frequency but different contrast, instead of the simple detection of points of light usual in adaptation methods. darkness. The test or visual stimulus is presented in such a way that it affects the center of the retina where cone photoreceptors predominate; this avoids the need to pharmacologically dilate the retina and the problems of loss of ocular fixation (they occur in the dark adaptation test where the patient has to detect a point of light that occurs in a position of the retina located about degrees of separation from the attachment point).
    [0046] Each time a stimulus is presented, the subject must give an answer about its orientation. The subjectivity of the patient's response is improved by implementing a forced-choice psychophysical procedure that, for example, has only four alternatives (choice of four possible orientations), rather than a simple "yes I see" or "I don't see" response. Depending on the response, the next stimulus is presented to have a higher or lower contrast level following a ladder procedure known in the art but modified.
    [0047] The mesopic luminance conditions of the invention are in the high mesopic range (for example 1.0 cd / m2 background) to favor that the visual detection is dominated by the cones and not by the rods (unlike the adaptation tests in the dark where luminance levels close to 0.0001 cd / m2 are used to favor the involvement of the rods on the cones).
    [0049] The duration of the measurement is 3 to 10 minutes in case of healthy eyes.
    [0051] The stimulus has the following characteristics:
    [0052] - greater luminance than the mesopic luminance of the background (between 0.1 and 5.0 cd / m2) on which said stimulus occurs,
    [0053] - low spatial frequency between 0.5 and 3 cycles / degree
    [0054] - contrast between 0.3% (log contrast = -2.5) and 100% (log contrast = -0.01) with contrast variation steps of at least 0.1 logarithmic units.
    [0055] - it has a detection characteristic whose orientation can vary in space, changing randomly each time said stimulus is presented, - it subtends a visual angle between 3 and 10 degrees,
    [0056] - is presented in such a way as to stimulate the central area of the macula at a distance between 50 and 150 cm from said patient and
    [0057] - has a spectrum of white light or spectral light to which the cones respond preferentially.
    [0059] The contrast levels detected by the subject and the times at which the detections were made during the test are recorded and analyzed to generate a function or curve that shows the recovery of sensitivity (inverse of the threshold) as a function of time and also to calculate the characterizing parameters of the recovery dynamics of contrast sensitivity. These parameters comprise, at least, the time constant or rate of regeneration of the cone pigment and the lower or final mesopic contrast threshold corresponding to the functioning of the ganglion cells.
    [0061] The characterizing parameters of the recovery dynamics of the subject's mesopic contrast sensitivity are compared with the parameters corresponding to a population of subjects with good ocular health of all ages included in a system normative database. This comparison allows to identify alterations in the characterizing parameters.
    [0063] The present invention also relates to a system that implements the measurement method described above. The system comprises:
    [0064] - A means to produce the whitening of visual pigments
    [0065] - A computer resource such as a computer or other electronic device for generating visual images equipped with a program or algorithm for programming and controlling stimulus presentation parameters (contrast, time, orientation)
    [0066] - A means of displaying the images;
    [0067] - A means to receive data that allows the patient to communicate his response to the stimulus to the computer;
    [0068] - A means of automatically recording contrast thresholds and time based on the response entered by the patient into the system. - A means of generating the test results and displaying the curve of the contrast thresholds as a function of time, the characterizing parameters of the recovery dynamics of the mesopic contrast sensitivity and a quality index of the measurement test; Y
    [0069] - A means of comparing said characterizing parameters with a normative database.
    [0071] To produce the whitening you can use a flash or a light bulb, for example.
    [0073] The computer, the display system and the lighting system can be integrated into a single structure.
    [0075] The program or algorithm allows to randomly modify the orientation of the detection characteristic of said stimuli in each presentation, increase or decrease the contrast of said stimuli depending on the response of a subject (401, 402, 403), vary the time interval between the presentation of said stimuli based on the response of said subject (404, 405), vary the time that the presentation of said stimuli lasts, to generate an auditory signal synchronized with the individual presentation of said stimuli, record the responses of said subject to said stimuli, record the contrasts detected and the time at which the detections have been made, and finish the test in the selected time.
    [0077] The contrast recorded in any of the embodiments is defined as the contrast threshold for that particular time.
    [0079] In this invention, the use of mesopic conditions together with the visual task of contrast detection (a task that is better solved by the cones) makes it possible to obtain a curve showing the time course of the recovery of contrast sensitivity measured by the cones and shorten the examination time to 5 minutes or less for healthy eyes instead of the usual 30 minutes in dark adaptation tests).
    [0081] BRIEF DESCRIPTION OF THE DRAWINGS
    [0082] To complement the description that is being made and in order to help a better understanding of the characteristics of the invention, a set of drawings is attached as an integral part of said description, in which, with an illustrative and non-limiting nature, the following has been represented following:
    [0084] Figure 1 shows a schematic representation of a patient performing a test to measure the recovery of mesopic contrast sensitivity after a transient glare of one eye.
    [0086] Figure 2 shows a schematic representation of a high resolution screen superimposed on a calibrated neutral density filter to reduce the luminance of the screen to mesopic levels in accordance with the present invention.
    [0088] Figure 3 shows the device or command to communicate the subject's response.
    [0090] Figure 4 shows how E-shaped images of visual stimuli of the same size change contrast and orientation based on a wrong and a correct response at a time point in the sequence of a test trial.
    [0091] Figure 5 shows a flow chart of the method of performing the dynamics test of recovery of mesopic contrast sensitivity according to the present invention.
    [0093] Figure 6 shows a recovery curve of the mesopic contrast sensitivity of an eye of a subject with normal vision measured by the method described. The abscissa axis indicates the recovery time and the ordinate axis indicates the contrast threshold whose inverse is the contrast sensitivity (a lower threshold indicates greater sensitivity): (a) time constant of the exponential component or rate of pigment regeneration of the cones; (b) final mesopic contrast threshold.
    [0095] Below is a list of the different elements represented in the figures that are integrated into the invention:
    [0097] 101 = subject or patient
    [0098] 102 = built-in high resolution display and computer
    [0099] 103 = electronic photo flash
    [0100] 104 = flash mount with an articulated side arm
    [0101] 201 = calibrated neutral density filter
    [0102] 301 = device or command for the subject's response
    [0103] 401 = image of an E stimulus with a given contrast
    [0104] 402 = image of an E stimulus with a contrast greater than the previous one in a medium step
    [0105] 403 = image of an E stimulus with a lower contrast than the previous one in three steps
    [0106] 404 = Time interval to present the next stimulus if the answer is incorrect
    [0107] 405 = time interval to present the next stimulus if the answer is correct.
    [0108] 501 = initial stage to temporarily dazzle a subject's eye under examination and whiten visual pigments
    [0109] 502 = successive presentation of stimuli on the screen at a chosen distance, increasing or decreasing the contrast level according to the response of a patient.
    [0110] 503 = obtaining a response from a subject about the orientation of a stimulus through a psychophysical method of forced choice.
    [0111] 504 = determination of contrast thresholds over time using a modified and automated scaling procedure during which stimulus contrast increases or decreases depending on a subject's response.
    [0112] 505 = record of contrast and stimulus time detected when the ladder is ascending.
    [0113] 506 = extraction of the characterizing parameters of the contrast sensitivity recovery function
    [0114] 507 = display on the screen of a contrast threshold curve as a function of time, the characterizing parameters of the function and a quality index of the test performed by the subject.
    [0115] 508 = comparison of the characterizing parameters of a subject or patient with a normative database contained in the computerized system.
    [0117] PREFERRED EMBODIMENT OF THE INVENTION
    [0118] The present invention is illustrated by the following examples, which are not intended to be limiting of its scope.
    [0120] Example 1.
    [0121] This example refers to the system where the measurement method is implemented.
    [0123] To measure the recovery time of contrast sensitivity, a computerized system is used that includes an electronic device (personal computer, laptop or tablet) where images can be generated and displayed. The system has a program for the generation of contrast modulated stimuli, according to the method of the invention, which are presented for display on a monitor or screen. It also has an automatic recording of the stimulus contrast and time as a function of the response entered into the system by the subject (101) looking at the screen.
    [0125] The screen or monitor where the stimulus is displayed is a device with good adjustable contrast resolution and optimal performance characteristics. The luminance of the screen should be at a high mesopic level. For this, the room where the test is done must be in the dark. The background luminance of the screen is close to 10 cd / m2 so it is reduced to a range between 0.1 and 5.0 cd / m2 (in this case up to 1 cd / m2) by superimposing a calibrated neutral density filter ( 201) on the screen. The filter can be made of different materials such as glass or plastic polymers and can be inserted into a support or filter holder (104) that is attached to the screen by means of clips. Alternatively, the subject may wear spectrally calibrated neutral density filter glasses to view the screen through. The device includes a sensor to measure screen luminance at mesopic levels, for example by means of a photometer with a USB port to transmit the measurement values to the computer or by means of a self-calibration system.
    [0127] The system also comprises a device for obtaining or receiving data from the patient such as the orientation of the stimulus displayed on the screen. In this example the device comprises a box with five buttons (301) on which the subject acts. The subject's task is to press a button referring to the orientation of the stimulus that is displayed on the screen. The device is a box whose front face has four buttons that correspond to each orientation of the stimulus detection characteristic, arranged in the four orientations (up, down, right, left). In addition, it has a button in the center for the case where the subject does not know the orientation. Instead of this response by pressing a button, the patient could give a verbal response to a voice recognition system. In an alternative embodiment, the device has between 2 and 4 buttons for possible orientations. In another alternative embodiment, if the patient is unsure or does not know the orientation they must press any button.
    [0129] Each time the subject or patient gives a response corresponding to the orientation of the stimulus displayed on the screen, another stimulus is presented with a different level of contrast and orientation.
    [0131] Example 2.
    [0132] This example refers to the glare method.
    [0134] The initial stage of the method of measurement of dynamics of recovery of contrast sensitivity, consists of a transient glare (501) of the eye of a subject to examination to produce a whitening of visual pigments. For this, an electronic photographic flash (103) is used that delivers a flash of high intensity white light in a very short period of time to the eye of a subject located in a dark room and whose pupil has been naturally dilated in the darkness. The intensity of the flash produces a whitening of 75-95% of the visual pigments. The eye that is not examined is kept covered.
    [0136] The flash is placed on a support (wall or floor) with an articulated side arm (104) so that the center of the flash is at the same height from the ground as the center of the screen where the stimuli are presented. It can also be integrated into a device that also contains the screen and the computer.
    [0138] The subject sits in a booster chair facing the screen and the height is adjusted so that the eye under examination is at the level of the flash in front. The subject should look directly at the center of the flash. The distance between the flash and the eye is 15 - 20 cm. The subject is instructed not to blink and to open his eye wide at the moment the flash operates.
    [0140] Example 3.
    [0141] This example refers to the stimulus presentation method.
    [0143] As an objective stimulus, shapes or symbols of a low spatial frequency are used, modulated in contrast, with a detection characteristic and which are always presented in a central position on the screen that corresponds to the center of the retina and in which the elements dominate. cone photoreceptors.
    [0145] The amount of contrast of the target stimulus is in the range between 0.3% (log contrast = -2.5) and 100% (log contrast = -0.01) and is expressed or recorded in logarithm; it is quantified using Weber's formula relating the luminance of the object and that of the background. The contrast variation steps are at least 0.1 log units.
    [0147] Object luminance -Background luminance
    [0148] Contrast =
    [0149] Background luminance
    [0150] The stimulus is letters E of the same size and square shape (401) whose lines and the spaces between lines are all the same height and length, similar to the grids used to measure contrast sensitivity. The separation between lines and spaces, in this case, is equivalent to a low spatial frequency close to 1 cycle / degree of visual angle, in the range between 0.5 and 3 cycles / degree. Under mesopic luminance conditions, the eye's sensitivity to detect contrast in a low spatial frequency stimulus is better or greater than to detect a high spatial frequency stimulus (the latter would need to have more contrast for its detection).
    [0152] In one case, for example, the size of the shape or letter is relatively large and subtends at least 5 degrees of visual angle to the distance of 1 meter so that both the fovea (in the center of the macula) and the paraphovea are stimulated (where the early stages of AMD are more likely to be altered). In other cases, the viewing distance and size may vary; for example, distances between 50 and 150 cm and sizes between 3 and 10 degrees.
    [0154] The stimulus is either a white light spectrum or is composed of at least one wavelength in the range of 550 to 650 nanometers (to which cones are more sensitive than rods).
    [0156] The orientation of the stimulus apertures, in this example, four (up, down, right or left) and is randomly changed in successive presentations over time and is unknown to the subject before viewing. In other alternative embodiments, the orientations may change and may be only 3 or 2 possibilities.
    [0158] Example 4.
    [0159] This example refers to the collection and receipt of data by the subject.
    [0161] The series of presentation of stimuli after the glare lasts approximately 5 minutes (between 3 and 10 minutes). During the test, the patient observes the screen that briefly presents the stimuli (502) and receives an auditory signal synchronized with the presentation of a new stimulus during for example 600 milliseconds, and then it is extinguished. The patient responds to the stimulus with a response and, based on this response on the orientation of the stimulus, the system adjusts the presentation of the next stimulus to have a higher or lower contrast level and also adjusts the time lapse between presentations.
    [0163] The subject must provide an answer about the orientation of the stimulus (503). In this example, the psychophysical method of response is a forced choice of five alternatives (up, down, left, right, or "I don't know") that provides a high level of clinical accuracy. The system records the answer as "correct," " wrong ”or“ don't know ”.
    [0165] The contrast to the stimulus changes over the time of the test session by means of an adaptive ladder procedure already known in the state of the art but modified and automated (504). In this example, the contrast of the stimulus increases 1.5 steps and decreases 3 steps depending on the response of the subject to the previous stimulus. If the subject's response is incorrect (404) or "don't know", the contrast of the next stimulus is increased, for example, by 0.15 logarithmic units (1.5 steps) or, alternatively, by 0.10 logarithmic units ( 1 step) This stimulus with higher contrast occurs after 1 - 2 seconds after the subject gives an incorrect or "don't know" response. When the subject identifies the orientation of the stimulus, the response is considered correct (405) and after 2 - 3 seconds the next stimulus is presented with a lower contrast (403) than the previous one (lower by 0.3 logarithmic units or 3 steps). Variations of the test procedure are easy to implement and, for example, contrast times and steps can be increased or decreased according to various possible combinations. Stimulus presentation trials continue until the test time ends or until an adjustment of a mathematical model performed simultaneously during the test finds that it is no longer necessary to continue any longer to obtain reliable parameters.
    [0167] The levels of contrast detected and the time are recorded as a function of the response of the subject to the stimuli presented during the test. Contrast and time are recorded (505) when, while the staircase procedure is in the ascent phase (the contrast is increased), the subject correctly identifies the orientation of the stimulus, that is, when the contrast of the stimulus correctly identified has a higher value than the stimulus previously presented. Alternatively, contrast and time are recorded the first time the stimulus is correctly identified, regardless of whether the ladder was ascending or descending. The contrast recorded in any of the embodiments is defined as the threshold for that particular time (the inverse of this threshold is the sensitivity).
    [0169] Example 5.
    [0170] This example refers to the method of analyzing the recorded data.
    [0172] The measured and recorded contrast thresholds and times are analyzed mathematically and statistically. In this example, the extraction of the characterizing parameters of the recovery of contrast sensitivity (506) is done by means of a mathematical fit to a decreasing exponential function model with nonlinear regression analysis technique or by principal component analysis. . Model fitting can be done as the contrast threshold values and time are recorded or when the test is complete.
    [0174] The characterizing parameters of the recovery dynamics include, at least, the time constant of the exponential component or rate of regeneration of the pigment of the cones (Figure 6, (a)) and the final mesopic contrast threshold (Figure 6 (b) ) indicative of ganglion cell function.
    [0176] A function of the recovery dynamics is generated as a curve of the logarithm of the contrast threshold as a function of time (Figure 6) that allows the results of the test to be visualized and that is shown to the subject (507). In addition, the characteristic parameters of the recovery dynamics of the mesopic contrast sensitivity are shown, as well as a quality index of the test.
    [0178] The characterizing parameters of a subject are compared with a normative database contained in the system (508) and that includes information related to the parameters of the dynamics of recovery of the sensitivity to mesopic contrast of a population of subjects with good ocular health and of all ages. This comparison allows us to know if there are alterations in visual function that can be attributed to the functioning of the external retina, the internal retina or both.
    权利要求:
    Claims (29)
    [1]
    1. Method for measuring the dynamics of recovery of the sensitivity to mesopic contrast of the eye of a subject or patient comprising the following steps: - Temporarily dazzling a subject's eye to whiten the visual pigments of the retina;
    - Present for short time intervals successive stimuli of constant size with a detection characteristic and modulated in contrast on a background of mesopic luminance;
    - Obtain a response to each successive stimulus to determine at each moment the contrast detected due to the recovery of contrast sensitivity mediated by cones by means of a psychophysical method of forced choice for a time;
    - Increase or decrease the contrast of the successive stimuli by means of an adaptive ladder procedure depending on the response of said subject to each presented stimulus;
    - Record the contrasts detected by the subject and the detection times;
    - Determine characterizing parameters of the recovery dynamics of the sensitivity to mesopic contrast from the analysis of the contrasts and times measured and recorded;
    - Show the curve of the contrasts detected as a function of time, the characterizing parameters and a quality index to measure proof. - Compare the data with a normative database.
    [2]
    2. Method for measuring the dynamics of recovery of the mesopic contrast sensitivity of the eye, according to claim 1, where in the dazzling stage the subject directs his gaze directly to a source of high intensity white light.
    [3]
    3. Method for measuring the dynamics of recovery of the mesopic contrast sensitivity of the eye, according to claim 2, where the whitening of the pigments of the cones of the central area of the retina reaches a percentage greater than 75%.
    [4]
    4. Method for measuring the dynamics of recovery of the sensitivity to the mesopic contrast of the eye, according to claim 2, where the glare is performed by means of a flash or other procedures such as adaptation fields with illuminated backgrounds or fixed gaze on a light bulb.
    [5]
    5. Method for measuring the dynamics of recovery of the mesopic contrast sensitivity of the eye, according to claim 1, where the presentation of stimuli is carried out successively in a room under mesopic conditions from the moment whitening is achieved until the subject's eye reaches the final contrast threshold that corresponds to its highest contrast sensitivity.
    [6]
    6. Method for measuring the dynamics of recovery of the mesopic contrast sensitivity of the eye, according to claim 5, where the mesopic conditions are in the high mesopic range (for example 1.0 cd / m2 background) to favor detection visual is dominated by cones.
    [7]
    7. Method for measuring the dynamics of recovery of the sensitivity to the mesopic contrast of the eye, according to claim 5, where the stimulus has the following characteristics:
    - greater luminance than the mesopic luminance of the background (between 0.1 and 5.0 cd / m2) on which said stimulus occurs,
    - low spatial frequency between 0.5 and 3 cycles / degree
    - contrast between 0.3% (log contrast = -2.5) and 100% (log contrast = -0.01) with contrast variation steps of at least 0.1 logarithmic units.
    - it has a detection characteristic whose orientation can vary in space, changing randomly each time said stimulus is presented,
    - subtend a visual angle between 3 and 10 degrees,
    - is presented in such a way as to stimulate the central area of the macula at a distance between 50 and 150 cm from said patient and
    - has a spectrum of white light or spectral light to which the cones respond preferentially.
    [8]
    8. Method of measuring the dynamics of recovery of contrast sensitivity mesopic of the eye, according to claim 7, where the stimulus is of a spectrum of white light or is composed of at least one wavelength in the range of 550 to 650 nanometers.
    [9]
    9. Method of measuring the dynamics of recovery of the sensitivity to mesopic contrast of the eye, according to claim 5, where the amount of contrast of the target stimulus is in the range between 0.3 and 100%
    [10]
    10. Method for measuring the dynamics of recovery of the mesopic contrast sensitivity of the eye, according to claim 5, where the stimuli are objects or figures always of the same size and low spatial frequency but different contrast and orientation that are presented at a fixed distance from the subject.
    [11]
    11. Method for measuring the dynamics of recovery of the mesopic contrast sensitivity of the eye, according to claim 10, where the stimulus is letters E of the same size and square shape whose lines and the spaces between lines are all the same height and length, equivalent to a low spatial frequency close to 1 cycle / degree of visual angle, in the range between 3 and 10 cycles / degree.
    [12]
    12. Method of measuring the dynamics of recovery of the sensitivity to the mesopic contrast of the eye, according to claim 1, where the response of the subject on the orientation of the stimulus is carried out by means of a psychophysical procedure of forced choice
    [13]
    13. Method for measuring the dynamics of recovery of the mesopic contrast sensitivity of the eye, according to claim 12, where the forced response has only five alternatives that correspond to each of the four possible orientations (up, down, left and right ) and another of ignorance of the orientation.
    [14]
    14. Method for measuring the dynamics of recovery of the eye's mesopic contrast sensitivity, according to claim 12, where the forced response has orientations that can be only 3 or 2 possibilities.
    [15]
    15. Method for measuring the dynamics of recovery of the sensitivity to mesopic contrast of the eye, according to claim 1, where the increase or decrease of the Contrasting of the successive stimuli is carried out using an adaptive ladder procedure depending on the response of the said subject to each presented stimulus.
    [16]
    16. Method for measuring the dynamics of recovery of the mesopic contrast sensitivity of the eye, according to claim 1, where the contrast levels detected by the subject and the times at which the detections have been made during the test are recorded and analyzed to generate a function or curve showing the recovery of the sensitivity (inverse of the threshold) as a function of time and also to calculate the characterizing parameters of the dynamics of recovery of the contrast sensitivity that comprise, at least, the time constant or cone pigment regeneration rate and lower or final mesopic contrast threshold corresponding to ganglion cell function.
    [17]
    17. Method of measuring the dynamics of recovery of the sensitivity to mesopic contrast of the eye, according to claims 1 and 16, where the parameters characterizing the dynamics of recovery of the sensitivity to mesopic contrast of the subject are compared with the parameters corresponding to a population of subjects with good ocular health of all ages included in a normative database of the system to identify in the subject's eye.
    [18]
    18. Method for measuring the dynamics of recovery of the mesopic contrast sensitivity of the eye, according to claim 1, characterized in that it is performed in a dark room without the need to dilate the pupil pharmacologically.
    [19]
    19. Method for measuring the dynamics of recovery of the mesopic contrast sensitivity of the eye, according to claim 1, characterized in that the duration of the measurement is 3 to 10 minutes in the case of healthy eyes.
    [20]
    20. Method for measuring the dynamics of recovery of the mesopic contrast sensitivity of the eye, according to claim 1, wherein the other eye of the subject not subjected to the measurement is kept covered by a patch.
    [21]
    21. Computerized system to implement the claimed method that comprises:
    - A means to produce the whitening of visual pigments
    - A computing resource such as a computer or other electronic device of generation of visual images provided with a program or algorithm for programming and control of stimulus presentation parameters (contrast, time, orientation)
    - A means of displaying the images;
    - A means to receive data that allows the patient to communicate his response to the stimulus to the computer;
    - A means of automatically recording contrast thresholds and time based on the response entered by the patient into the system. - A means of generating the test results and displaying the curve of the contrast thresholds as a function of time, the characterizing parameters of the recovery dynamics of the mesopic contrast sensitivity and a quality index of the measurement test; Y
    - A means of comparing said characterizing parameters with a normative database.
    [22]
    22. Computerized system according to claim 21, wherein the luminance of the display medium is reduced to mesopic levels between 0.5 and 5.0 cd / m2 by superimposing between said medium and the subject one or more calibrated neutral density filters.
    [23]
    23. Computerized system, according to claim 21, where the computer, the display system and the lighting system can be integrated into a single structure.
    [24]
    24. Computerized system, according to claim 21, where the program or algorithm for programming and control of stimulus presentation parameters allows randomly modifying the orientation of the detection characteristic of said stimuli in each presentation, increasing or decreasing the contrast of said stimuli depending on the response of a subject (401, 402, 403), vary the time interval between the presentation of said stimuli depending on the response of said subject (404, 405), vary the time that the presentation of said stimuli, to generate an auditory signal synchronized with the individual presentation of said stimuli, record the responses of said subject to said stimuli, record the contrasts detected and the time at which the detections have been made, and finish the test in the selected time.
    [25]
    25. Computerized system, according to claim 21, wherein the means of communication with the patient is a device comprising a box with buttons (301) on which the subject acts.
    [26]
    26. Computerized system, according to claim 25, where the device is a box whose front face has four buttons that correspond to each orientation of the stimulus direction characteristic, arranged in the four orientations (up, down, right, left), in addition , and it has a button in the center for the case where the subject does not know the orientation.
    [27]
    27. Computerized system, according to claim 25, where the device is a box that has between 2 and 4 buttons for the possible orientations.
    [28]
    28. Computerized system, according to claim 21, where the patient is not sure or does not know the orientation must press any button.
    [29]
    29. Computerized system, according to claim 20, wherein the means of communication with the patient is a voice communication device.
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    同族专利:
    公开号 | 公开日
    WO2021209669A9|2022-01-13|
    WO2021209669A1|2021-10-21|
    ES2785082B2|2021-08-19|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    US5864384A|1996-07-31|1999-01-26|Mcclure; Richard J.|Visual field testing method and apparatus using virtual reality|
    US6315412B1|1997-12-05|2001-11-13|The Schepens Eye Research Institute, Inc.|Method and apparatus for measuring visual sensitivity and optical properties of components of the eye|
    US20170055825A1|2014-04-24|2017-03-02|Carl Zeiss Meditec, Inc.|Functional vision testing using light field displays|
    US20170290505A1|2014-09-22|2017-10-12|Carl Zeiss Meditec Ag|Visual field measuring device and system|
    WO1990001290A1|1988-08-12|1990-02-22|Vismed, Inc.|Automated ocular perimetry, particularly kinetic perimetry|
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    PCT/ES2021/070253| WO2021209669A1|2020-04-17|2021-04-16|Method and system for measuring the dynamics of mesopic contrast sensitivity recovery|
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