RU2196497C2 - Device for diagnosing vision system pathologies in children based on critical frequency of flicker fusion - Google Patents

Abstract

FIELD: medical engineering. SUBSTANCE: device has casing enclosing means for producing impulses which outputs are connected to two photostimulation units designed as photodiodes fixed in light protection screen mounted on toy car headlight and power supply source unit electrically coupled with the means for producing impulses. The means for producing impulses is designed as microprocessor usable for producing controllable frequency impulses within the limits of 1 to 60 Hz. The device also has transceiver unit operating on infrared radiation mounted inside of the casing and connected to microprocessor and usable for receiving and transmitting data. Indicator unit is connected to the microprocessor for showing critical flicker fusion frequency inherent in the right and left child eye. EFFECT: simplified diagnosis procedure. 5 cl, 3 tbl

Description

 The invention relates to ophthalmology, and more specifically to a device for diagnosing pathology of the visual system in children at the critical fusion flicker frequency.

 The invention can be used to diagnose the visual system in children, and children’s toys, in particular a toy car, in the headlights of which a diagnostic tool is integrated into the headlights, can be used as part of the device. The invention can be used for differential diagnosis of the functional state of the retina and optic nerve, pathology of the optic nerve.

 It is known that a person who is still in relation to the retina ceases to see after 1-3 seconds, and visual perception occurs only when the brightness, color or position of the object changes. Information about immovable objects or during prolonged exposure is transmitted through the visual path only due to eye tremors, which is carried out with a frequency of 30 Hz. Inadequate long-term light and color exposure - flare and color music - in some diseases of the retina and optic nerve causes a violation of photochemical and metabolic processes in the retina.

 Light perception and color perception are the basis on which other functions of vision are built. The most important of them is the distinction and recognition of the shape of objects. For its implementation, it is not the absolute sensitivity of the eye to light and color that is important, but the sensitivity to their changes in space and time - the so-called contrast sensitivity, expressed by numerous quantitative relationships established experimentally - by the psychophysical laws of vision.

 Distinguish contrast sensitivity - spatial and temporal. Temporary contrast sensitivity is the minimum frequency of flickering of stimuli per unit time, at which the phenomenon of fusion of individual visual sensations already occurs. This phenomenon is called the critical flicker fusion frequency (CFSM). At present, in ophthalmology, the use of time-frequency indicators, which expand information and reveal the features of the nature of vision and its functional disorders, is becoming increasingly important.

 CSFM is independent of visual acuity, refraction, and pupil size. However, it was found that CSFM changes under the influence of side stimuli: sound, olfactory, taste and tactile.

 In pediatric ophthalmology, very often, early diagnosis of pathology of the retina and optic nerve causes difficulties due to the microsymptomatic picture of clinical signs in the fundus, which leads to diagnostic errors. In order to clarify the diagnosis and differential diagnosis, additional psychophysical and electrophysiological studies have to be carried out, which are often difficult for children to carry out, but are now very expensive. Currently, preference is given to time-frequency techniques. The instruments used are compact and easy to use.

 A known method for diagnosing the degree of human fatigue (see, for example, patent SU 1445694 Ovchinnikova ND, A 61 B 5/16), which consists in placing a light-protective spectacle frame in front of the patient's eyes with LEDs connected to the front panel connected to means for generating and generating light pulses of different wavelengths, light pulses of green blue and red are supplied to the LEDs and the functional state of the visual system is diagnosed.

 Light flickers are shown simultaneously on both eyes paracentrically and the difference in the critical frequency of flicker fusion (CFSM) determines the degree of interhemispheric functional asymmetry of the brain, which is used to judge the degree of fatigue of the examined patient. However, the proposed method does not allow the diagnosis of the functional state of the visual system and, in particular, the central zone of the retina, excludes the use of color stimuli and does not determine their significance. The method does not allow simultaneous restoration of visual functions.

 This method is difficult to use to diagnose the pathology of the visual system in a child, since the child is often afraid to put on a sun glasses frame with built-in LEDs. The child also can not give an exact answer to the doctor’s questions in the diagnosis.

 A device is known for diagnosing and restoring visual functions (see, for example, RF patent 2071301), comprising a housing in which a pulse generator is located, the outputs of which are connected to two light stimulators fixed in a light-shielding screen, and a power supply unit that is electrically connected to the pulse generator .

 Using this device, both eyes of the patient are exposed to light of the same wavelength lying in the visible region of the spectrum 400-700 nm, illuminance 5 - 100 lux. In this case, one or both eyes are affected by flashing light radiation with a blinking frequency of 0.06 - 1 Hz. The specified device will restrain glasses with light-insulated eyepieces, each of which has a light-diffusing reflector, inside which a source of light radiation is fixed and installed in front of it with the possibility of replacing a light filter.

 The device also contains a regulator of the frequency of flashing light radiation, a regulator of the brightness of light radiation, a switch that provides a given light effect on each eye, and a power supply.

 The specified device is difficult to use for diagnosing the pathology of the visual system in a child, since the child is often afraid to put on a sun glasses for glasses with built-in LEDs. The child also can not give an exact answer to the doctor’s questions in the diagnosis.

 The basis of the present invention is the creation of a device for diagnosing pathology of the visual system in children at a critical flicker fusion frequency, in which the placement of device elements in the body and in the headlights of a toy car, the connection between which is carried out by means of infrared radiation, will allow the diagnosis of violations of the child’s visual system , i.e. functional state of the retina and optic nerve.

The problem is solved in that in the device for diagnosing the pathology of the visual system in children at the critical flicker fusion frequency, comprising a housing in which there is a means for generating pulses, the outputs of which are electrically connected to two light stimulators made in the form of LEDs mounted in a light-shielding screen, which is installed in the headlights of a toy car, and a power supply unit that is electrically connected to the means for generating pulses, according to the invention
means for generating pulses is made in the form of a microprocessor, by means of which pulses of an adjustable frequency are generated in the range 1-60 Hz,
and the device also contains a transceiver on infrared radiation, mounted in the housing, connected to a microprocessor and designed to receive and transmit data,
an indicator connected to the microprocessor to indicate indications of a critical flicker fusion frequency for the child’s right and left eyes,
a control panel connected to the microprocessor with a switch, on which there is a control button for turning on the microprocessor, a button for adjusting the brightness of the light stimulus, a button for switching the color of LEDs, a button for turning on the transceiver on infrared radiation, for switching the readings on the indicator for the left and right eyes, the button for connecting one from light stimulators to the power supply installed on the car,
at the same time, in the case of the toy car, a second infrared radiation transceiver is connected in series, connected to a power supply unit installed on the car and intended for receiving and transmitting data from the microprocessor, and a second microprocessor for generating the pulse width of the adjustable frequency and stabilizing the current supplied to the LEDs, connected to a power supply and electrically connected to the first and second light stimulators.

 It is useful that the device contains an adapter for connecting the power supply to the mains.

 It is advisable that each LED is a multi-color LED.

 Advantageously, LEDs having at least three primary colors selected from the group consisting of red, green and blue are used.

The invention is further explained in the description of the preferred options for its implementation with reference to the accompanying drawings, in which:
FIG. 1 depicts a general view of a device for diagnosing pathology of the visual system in children at the critical flicker fusion frequency, according to the invention;
FIG. 2 depicts a block diagram of a device for diagnosing pathology of the visual system in children at the critical flicker fusion frequency, according to the invention.

 A device for diagnosing pathologies of the visual system in children at a critical flicker fusion frequency comprises a housing 1 (Fig. 1), in which there is a means 2 for generating pulses, outputs 3, 4 of which are electrically connected to two light stimulators 5, 6, made in the form of LEDs, fixed in the light shield 7, 8, which is installed in the headlights 9, 10, respectively, of the toy car 11. The device also includes a power supply 12, which is electrically connected to the means 2 for generating pulses.

 The car 11 has a power supply unit 13.

 Means 2 for generating pulses is made in the form of a microprocessor, by means of which pulses of an adjustable frequency are generated in the range of 1 - 60 Hz.

 The device also contains a transceiver 14 on infrared radiation, mounted in the housing 1, connected to the microprocessor 2 and designed for receiving and transmitting data.

 An indicator 15 is connected to the microprocessor to indicate indications of a critical flicker fusion frequency for the child’s right and left eyes.

 A control panel 16 with a switch is also connected to the microprocessor, on which there is a control button 17 for turning on the microprocessor and the transceiver on infrared radiation, a light stimulus brightness adjustment button 18, LED color switching button 19, a flicker fusion frequency increase button 20, a frequency decrease button 21 flicker fusion, button 22 to switch the readings on the indicator for the left and right eyes.

 At the same time, in the case of the toy car 11, a second infrared radiation transceiver 23 is connected in series, connected to the power supply unit 13 installed on the car 11 and intended for receiving and transmitting data from the microprocessor, and a second microprocessor 24 for generating a controlled pulse width, connected to power supply unit 13 and to the first and second light stimulators 5 and 6.

 In a preferred embodiment, the device includes an adapter 25 for connecting the power supply unit 12 or the power supply unit 13 to the mains.

 Each light stimulator 5, 6 is a multi-color LED.

 The device uses LEDs having at least three primary colors, for example, red, green and blue.

 The operation of the device for diagnosing the pathology of the visual system in children at the critical fusion flicker frequency is as follows.

 Before testing, according to the age of the child, they introduce him to a toy device and examination methods. It is advisable to conduct a test determination of CFSM binocularly to clarify the child's understanding of the purpose of the examination without registering the evidence.

 Examination is carried out for each eye separately. It is advisable for children with ametropia to conduct studies in the optimal spectacle correction. A child with headlights turned on is presented to the child from a distance of 25-30 cm. At the same time, one of the headlights is constantly on, and on the other headlight, the light flickers with a constantly increasing flicker frequency, which the doctor smoothly adjusts with buttons 20, 21. In the case of a monocular pathology of the child, it is advisable to begin the examination of the CESF from the eye that sees better.

 They begin the examination with the eye that sees better, with red, then they show green, and then blue, switching button 19. At the moment when the child stops distinguishing flickering, he should immediately signal the doctor, for example, say “stop”. Then button 22 switches the device to the other eye.

 At this point, the adjustment of the CFCF stops and the measurement result is displayed on the screen. This is the first test result of CFSM (P1).

 Then the study is carried out in the reverse order, i.e. begin testing with a maximum flicker frequency of the color test, gradually reducing the frequency of the light signal. At the moment when the child indicates the appearance of flicker of the color test, the doctor fixes the result on the screen (P2).

The result of the CFSM of a given child is determined by calculating the arithmetic mean of these two quantities
CFCF = (P1 + P2) / 2.

 P1 is normally always higher than P2 as a result of existing visual inertia in the form of a sequential image.

 The CSFM for healthy children was also determined by examination on these devices, the results of which are shown in table 1.

 Peculiarities of changes in CSFM were revealed for various pathologies of vision.

 The determination of CFSM for color stimuli was carried out in children aged 4 to 15 years - 50 healthy children (100 eyes) and 259 children with diseases (518 eyes) with various eye pathologies. As a result of these studies, indicators of normal values in healthy children for stimuli of red, green and blue on the claimed device were obtained.

 Determination of the critical frequency of flicker fusion in children with pathology of the retina, optic nerve and amblyopia has shown high efficiency (up to 83%) with low-symptomatic changes in the fundus.

 The results of the studies showed that CFSM depends on the severity of damage to the visual system and is practically independent of visual acuity. Examples of diagnosis of vision of various pathologies are given below.

 Example 1

 Amblyopia.

 We examined children with refractive anisometropic and dysbinocular amblyopia according to the classification of E.S. Avetisova (1964) with a high, medium and low degree. The results are presented in table 2.

 As a result of the CFSM study on color stimuli, there were no statistically significant differences in the indicators between the amblyopic and healthy eyes, as well as in comparison with those in healthy children.

 Indicators of CFSM for color stimuli in children in the group with refractive, anisometropic and dysbinocular amblyopia of varying degrees were high.

 Example 2

 Congenital high myopia.

 A group of children with congenital high myopia was examined, given its great importance in the etiology of low vision. A feature of congenital myopia, as a rule, is low corrected visual acuity. The reasons for this are organic changes in the visual system - the relatively long axis of the eye, the strong refractive power of the lens, subluxation of the lens, degenerative changes in the retina, partial atrophy of the optic nerve, and relative amblyopia associated with both these changes and prolonged projection onto the retina of obscure images of objects of the outside world. During the examination of children in this group, the average visual acuity was 0.31 + 0.02 (p <0.01). All children showed a decrease in CFSM for colored stimuli. The mean values for the red stimulus were 38.4 + 0.5 Hz (+ 4.28), the green stimulus 40.0 + 0.6 Hz (+ 4.8) and the blue stimulus 36.5 + 0.6 Hz (+ 5.0). A statistically significant (p <0.02) correlation was observed between the degree of decrease in CSFM and organic changes in the fundus. These results were combined with a 30 Hz decrease in RERG by an average of 29%. According to the SCLC data, a slight decrease in the P1000 amplitude was noted by an average of 11% (p = 0.02) with normal latency indicators.

 Thus, CSFM in congenital myopia reflects lesions of all neurons of the retina and thereby reflects the safety of the papillomacular bundle.

 The results of measuring CFSM for color stimuli using the claimed device. Are given in table 3.

 Example 3

Partial optic atrophy
Children with ChASN congenital and postneuritic etiology had different visual acuity. A group of children with visual acuity from 0.05-0.09 was studied; s 0.1-0.2; from 0.3-0.4; 0.5-0.6 and 0.7-0.8. During ophthalmoscopy of children with congenital and postneuritic ChASN, changes in the fundus in the form of optic nerve decoloration and secondary changes in the macular region were detected in 64% of cases, and in 36% of cases, changes in the fundus were not detected.

 According to the results of the CFSM study (see table 2 and table 3), there was a decrease in indicators for red, green, and blue stimuli not only in the eye with low vision, but also in the controlled eye with high visual acuity and statistically significant (p, 0.01) . This confirms the defeat of the pathological process of the visual system of both eyes, but to varying degrees.

 It is necessary to pay attention to fluctuations in the results of the CFSM. Typically, the value of CFSM remains constant over the entire age of a healthy person, and changes with the pathology of the visual system. So, in the stage of an active inflammatory process in the visual analyzer, fluctuations in the results of CSFM can be from 14-18 Hz, the period of restoration of visual functions to 28-38 Hz (p <0.02), but never increase to normal values. The average values of CFSM in children of this group were for the red stimulus 32.6 + 1.1 Hz (+7.5), for the green stimulus - 34.7 + 1.1 Hz (+7.4) and for the blue stimulus colors - 31.7 + 0.8 (+5.6).

 Electrophysiological studies in children with ChASN revealed a decrease in the amplitude of the positive peak P100 of the SCD. an average of 37.5% (p = 0.2) and an increase in latency of 14% (p = 0.2), which indicates a decrease in the number of normally functioning fibers in the optic nerve.

 The total ERG indices were slightly changed, namely, a decrease in the amplitude of wave "a" by 27% (p = 0.2) was noted. There was also a slight decrease in the amplitude of the RERG by 30 Hz by an average of 29% (p <0.2), which indicates a secondary decrease in the function of the cone system of the retina of the macular region in children of this group.

 Consequently, the decrease in the CSFM indices for color stimuli in children with CHASN corresponded to an insignificant degree of damage to the first optic neuron (retinal photoreceptors) and to a greater extent to the third optic neuron of the optic nerve, which is confirmed by electrophysiological studies.

 Example 4

 Congenital and hereditary lesions of the cone apparatus of the retina.

 Difficulties in the correct diagnosis of this disease at an early age often lead to diagnostic errors. Hypofunction of the cone apparatus is characteristic of cone dysfunction or dystrophy. The main symptoms are photophobia (day blindness), uncorrectable low vision, impaired color sensation in various variations, and improved vision at dusk. The corresponding symptom is often characteristic - nystagmus. The changes in both eyes are symmetrical. The ophthalmoscopic fundus picture at an early age of the child, as a rule, is not very symptomatic: the absence of a macular reflex, a brighter foveolar region. With the progression of the process, a slight dispersion of the pigment in the form of an oval is detected.

 Children in the initial stage of the disease were observed. The average visual acuity in children of this group was 0.1 + 0.01 (p <0.01), the violation of color perception was similar to achromatopsia in all patients (100%).

 CFSM was sharply reduced for color stimuli (see table 3) and the average values were: for the red stimulus - 16.7 + 1.0 Hz (+3.4), for the green stimulus - 20.8 + 1.1 Hz ( +4.4) and the blue stimulus 21.2 + 1.5 Hz (+6.5). According to the results of an electrophysiological examination, a sharp decrease in rhythmic ERG by 30 Hz to 81% (p <0.02), a decrease in wave "a" of the total ERG by 41% (p <0.02) was revealed. In the study of CDWC, the amplitude of the positive P100 peak decreased by 79% (p <0.02) with normal latency values.

 Example 5

 Central tapetoretinal abiotropy of the Stargardt retina.

 The examined children with central TPA had the second stage of the disease in 13% of cases, the third stage of the disease in 65% of cases and the fourth stage of the disease in 20.7% of cases according to Katznelson's classification (1976). Changes in the fundus in children in both eyes were symmetrical. The average visual acuity in children was 0.1 + 0.01. In all children, color perception was impaired from red-green dichromatopsia to complete achromatopsia. During an ophthalmoscopic examination, the picture on the fundus was from the presence only in the macular region of mottling and bifurcation of the macular reflex to changes typical for central TPA - the absence of a macular reflex, the presence of rough pigment mottling spreading outside the macular region. In several cases (14 eyes), changes were observed at the periphery of the fundus in the form of deposition of pigment of various shapes and sizes, as well as limited areas of chorioretinal atrophy.

 In children with this disease, a sharp decrease in CSFM for color stimuli (see, for example, Table 2 and Table 3) was statistically significant (p <0.02), the average statistical values of which amounted to 26.6 + 0.5 Hz per red stimulus (σ + 3.7), and on the green stimulus 27.7 + 0.6 Hz (σ + 2.8).

 Analysis of electrophysiological data revealed a statistically subnormal total ERH in children of the second stage of the disease. In children of the third and fourth stages of the disease, a decrease in amplitude and an increase in the temporal indicators of total ERG were noted. So the amplitude of wave "a" was significantly reduced on average by almost 50% (p = 0.02), and the amplitude of wave "b" - by 62% (p <0.01). The rhythmic ERG at 30 Hz was reduced by 77% (p <0.01), which indicates organic changes in the cone-shaped system of the outer layers of the retina. Moreover, according to the data of the CDW recording in children with central TPA of the third and fourth stages, a significant decrease in the amplitude of P100 was noted by 60% (p <0.01), and the total cortical time remained within the normal range, i.e. the third optic neuron was intact.

 Thus, it was found that in case of damage to the external part of the retina, i.e., the first neuron of the optic pathway (photoreceptors), the CESM index for color stimuli is sharply reduced.

 Example 6

 Juvenile X-chromosomal retinoschisis.

 From a large group of diseases uniting the retinoschisis, the hereditary X-chromosomal juvenile retinoschisis is distinguished, because when it is diagnosed, a high frequency of diagnostic errors is observed. The following changes were noted in the group of children with X-chromosomal juvenile retinoschisis, which were relatively symmetrical in both eyes. Visual acuity was different and ranged from 0.6 to 0.1. All children had normal color sensation. A different ophthalmoscopic picture in the macular region was revealed on the fundus: only redistribution of the pigment, redistribution of the pigment and cystic changes in the form of "spokes in the wheel", only the fevolar retinoschisis. Changes in the lower outer periphery were observed in all children, but in varying degrees of severity from flat retinoschisis to retinal detachment with a small gap and vitreoretinal moorings.

 Studies of CSFM in children of this group revealed a decrease in indicators in both eyes for both red and green stimuli. It was noted that the degree of CFSM reduction corresponded to the severity of the pathological process and averaged 33.1 + 0.9 Hz (σ = +5.7) for the red stimulus and 34.1 + 1.8 Hz for the green stimulus ( σ = + 4.7) (table 2).

 In the X-chromosomal juvenile retinoschisis, the total ERG had subnormal values or negative negative ERG - the decrease in the amplitude of wave "b" was on average 58.2% (p = 0.05), and the RERG by 30 Hz was significantly reduced - an average of 61.2% (p <0.02).

 The amplitude of the positive peak P100 of the SCLC was reduced on average by 37% (p = 0.02), and the cortical time remained within normal values.

 Therefore, in children with X-chromosomal retinoschisis, the incidence of FSM for color stimuli was lower than in children with ChASN, but higher than in children with central Stargardt TPA. These results reflect the pathogenesis of the disease, starting with the defeat of the third neuron of the visual analyzer, the retinoschisis in the layer of nerve fibers of the inner layer of the retina and the progression of the pathology into the outer layers. The results of CSFM corresponded to the results of electrophysiological research methods that reflect the organic pathological process in the outer and inner layers of the retina.

 It can be seen from the results of the studies that the CFSM indicators for color stimuli in healthy children and in children with refractive and dysbinocular amblyopia were the highest. The lower rates were among children with congenital and postneuritic etiology, and the lowest rates were among children with central Stargardt TPA. These data are of practical importance for the diagnosis of vision in children with pathology of the retina and optic nerve.

 Marked changes in CFSM to color stimuli reflect organic disturbances in the visual system, and the degree of decrease in CFSM reflects the topic and severity of the lesion of the visual analyzer. The lower the CFSM, the more severe the damage to the visual system. The lowest levels of CSFM were found in diseases of the retinal photoreceptors (Stargardt's disease). The diagnostic value of the results of the CFSM study on colors is confirmed by objective data of electrophysiological studies of the organ of vision. The study of visual functions in children using the claimed device is recommended for early diagnosis and prognosis of diseases of the retina and optic nerve, during a routine examination of children, a comprehensive ophthalmological examination of children for diagnostic purposes.

Claims (4)

 1. A device for diagnosing pathology of the visual system in children at a critical flicker fusion frequency, comprising a housing in which there is a means for generating pulses, the outputs of which are electrically connected to two light stimulators made in the form of LEDs mounted in a light-protective screen that is installed in the headlights of a toy a car, and a power supply unit that is electrically connected to the means for generating pulses, characterized in that the means for generating pulses is made in the form of a microprocessor, by means of which an adjustable frequency pulse is generated in the range from 1 to 60 Hz, and the device also contains an infrared transceiver installed in the housing, connected to the microprocessor and designed to receive and transmit data, an indicator connected to the microprocessor to indicate indications of the critical fusion frequency flickering for the right and left eyes of the child, a control panel with a switch connected to the microprocessor, on which a control button is placed to turn on the microprocessor RA, the button for adjusting the brightness of the light stimulus, the button for switching the color of the LEDs, the button for turning on the transceiver on infrared radiation, the button for switching the readings on the indicator for the left and right eyes, the button for connecting one of the light stimulators to the power supply installed on the car, while in the toy body The vehicle is equipped with a second IR transceiver connected in series, connected to a power supply installed on the vehicle and designed to receive and transmit data. microprocessor, and a second microprocessor for forming the pulse width of the adjustable frequency and stabilize the current supplied to the LEDs connected to the power supply and electrically connected to the first and second light stimulators.  2. The device according to p. 1, characterized in that it contains an adapter for connecting the power supply to the mains.  3. The device according to claim 1, characterized in that each LED is a multi-color LED.  4. The device according to claim 1, characterized in that the LEDs are used having at least three primary colors selected from the group consisting of red, green and blue.

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