RU2190343C2 - Method for determining duration of human vision perception latent period - Google Patents

Abstract

FIELD: medicine. SUBSTANCE: method involves wearing sun protection glasses having light emission source (photodiode) is mounted in front of eyeball center at a distance being less than focal distance of the eye. Current providing background brightness of the radiation is supplied to the photodiode. The testee observes light spot the diameter of which is proportional to eye pupil diameter (test object). Photodiode current is jump-wise increased during preset time interval at given time moment and then, the photodiode current takes its initial value corresponding to background radiation intensity. Some time later being Ti time, determined by the testee in a series of repeated tests, the light dies out showing the moment the testee has taken decision concerning test object diameter changing. Ti background brightness light source illumination time mean value and variance are determined from data received in N trials usable as basis for drawing conclusions concerning duration of human vision perception latent period. EFFECT: higher accuracy and reliability of measurements. 2 cl, 2 dwg

Description

 The invention relates to medical equipment and can be used to measure parameters of visual perception during psychophysiological studies or professional examination.

 A known method for a similar purpose, implemented in the device [1], with which the latency of the human visual analyzer is studied. The test subject sits in front of the cabinet, on the front wall of which there is a rotating disk. In the center of the disk is a fixed light source. The disk has a gap along which a second light source moves. The test subject fixes his gaze on a fixed light source and moves the second light source using a manual remote switch until he no longer notices the differences between the moments when the two light sources are turned on. Then the disc is rotated to the next of 12 angular positions and the test is repeated. Based on the obtained indicators, graphs of equal visual delay are constructed. The resulting heterogeneities and / or deviations in the graphic display compared with the normal reaction can indicate excessive transmission time delays in the part of the optical nerves caused by overwork or illness of the nervous system.

 The disadvantage of this method [1] is that the moment the two light sources are turned on causes a pupil reaction, which introduces an additional error when measuring the latent period of visual perception of test objects.

 A known method for a similar purpose [2], according to which the test object is stabilized by a vacuum suction cup relative to the retina of the dominant eye against the background of the screen, uniform in brightness and color. Provide uniform illumination of a stationary test object and background screen of the order of 500-800 lux. A light pulse of 8000-10000 lux is applied to the retina of the second eye through the frosted glass at the level of the pupil with a duration of 0.01-0.03 s. The light pulse causes a combined reaction of the pupils: both pupils decrease in diameter by 1.5-2.0 times. As a result of this, the subject has a vision of the test object. The test object appears to the observer after 0.25-0.3 s after exposure to light in the second eye. The clarity of perception increases over the next 30-60 s to a maximum, after which it begins to fade and is gradually replaced by an "empty field".

 This method [2] adopted as a prototype.

 The disadvantage of the prototype is the contact method of fixing the test object using a vacuum suction cup on the eyeball, which requires a long period of adaptation of the test person before measurement, introduces an additional error in the measurement of the latent period of visual perception and in conditions of mass research is unacceptable according to hygiene standards.

 The technical effect obtained from the implementation of the invention is to increase the accuracy of measuring the latent period of visual perception of the test object and reduce the examination time, expand the scope of the device due to the exclusion of direct contact of the device with the eye of the subject. In this regard, the diagnosis of the functional state of a person becomes possible in any conditions, including extreme (pilot, astronaut, etc.).

This technical result is obtained due to the fact that in the known method for determining the latent period of human visual perception, which consists in the formation of a test object with uniform background illumination of 500-800 lux stabilized relative to the retina of the subject and exposure to the pupil of the eye with a flash from a light source of luminosity 8000- 10,000 lux, during the subsequent fixation by the subject of changes in the diameter of the pupil of the eye under the influence of a flash of light, the pupil of the subject is used as a test object, and regular enrollment light a from the eye at a distance less than the focal length, wherein after the flash light form the illumination pulse with an amplitude equal to the background predetermined duration T _and the trailing edge coincides with the perception point test start reducing its pupil, and the value _{T, and} determines the latency period optic perception of the pupillary reaction of a person.

 In addition, N tests of the same type are additionally carried out, the average latent period of the visual perception of the pupil’s reaction of the person and its dispersion are found, which are used to judge the functional state of the test person or the physiological characteristics of his visual analyzer.

 The invention is illustrated in the drawing, figure 1 which presents a block diagram of a device that implements the method; figure 2 is a timing chart of the current control light source (LED) and the change in the diameter of the pupil depending on the illumination when measuring the latent period of visual perception.

The device for implementing the method comprises (Fig. 1) a microprocessor unit, four push-button switches S1-S4 and a VD LED. In the device, when the push-button switch S1 is pressed, the light stimulus is started, and with the help of the push-buttons S2 and S3, the interval T _and can be adjusted (Fig. 2). By pressing pushbutton switch S4 setpoint interval T _and stored in the memory of the microprocessor unit.

 The method is implemented as follows.

The VD LED is mounted, for example, on dark glasses, so that when the subject wore dark glasses, the light source would be installed against the center of the eyeball at a distance that is less than the focal length of the eye. A current is supplied to the LED, providing background illumination (luminosity) of the order of 500-800 lux (background). The subject observes a light spot whose diameter is proportional to the size of his pupil. At some point in time, after pressing the button S1, the LED current increases stepwise, providing the LED (stimulus) luminosity of 8000-10000 lux for 0.01-0.03 s (interval T ₁ ), after which the LED current returns to its original value, corresponding to the background radiation intensity, and after a time T _and goes out for a time T ₂ . As a result of the light stimulus, the pupil contracts and, consequently, the observed light spot decreases in diameter. Using the push-button switches S2 and S3, the test subject needs to set the duration T _and such that the LED goes out at the moment the pupil begins to contract. The selected value of the interval T _{and is} entered into the memory of the microprocessor unit by pressing the button switch S4.

 According to the results of N tests (for example, N = 10), the average value of the latent period of visual perception and its variance are found, which are used to judge the functional state of the subject (fatigue, drug intoxication, etc.) or the physiological characteristics of the visual analyzer. This achieves the set technical result.

Sources of information
1. USSR copyright certificate 572177, cl. A 61 B 3/00, 1973.

 2. USSR copyright certificate 1273052, cl. A 61 B 5/00, 1982 (prototype).

Claims (2)

1. The method for determining the latent period of human visual perception, which consists in the formation of a test object with uniform background illumination of 500-800 lux, stabilized relative to the retina of the subject, and exposure to the retina with a flash from a light source, luminosity of 8000-10000 lux and a duration of 0.01 -0.03 s when the subject subsequently observes the light spot, characterized in that the test pupil is used as the test object, the diameter of which is proportional to the size of the light spot, and the source is Veta is placed at a distance shorter than the focal length from the eye, and after a flash of light, during a series of attempts, an illumination pulse is formed with an amplitude equal to the background given duration T _and whose trailing edge coincides with the moment the subject perceives the beginning of the decrease in the diameter of the light spot observed by him, and the value of T _and determine the latent period of visual perception of the pupillary reaction of a person.  2. The method according to claim 1, characterized in that they additionally carry out N similar tests, find the average latent period of the visual perception of the pupil’s reaction of a person and its dispersion, which are used to judge the functional state of the subject or the physiological characteristics of his visual analyzer.

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