RU2651126C1 - Method of early detection of age-related macular degeneration of the retina - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: invention refers to medicine, namely to ophthalmology. Light excitation of the autofluorescence of the ocular fundus is performed. Light signal of the LED with a peak wavelength of 488 nm is used. Intensity of the excited autofluorescence in the spectral region 1 corresponding to the range 530–580 nm and in the spectral region 2 corresponding to the range of 600–650 nm is recorded. With the help of mathematical processing, the values of the integral intensities of the signals of autofluorescence I₁ and I₂ in the spectral regions 1 and 2, respectively, are obtained. Diagnostic criterion is calculated as the ratio I₁ to I₂. If a diagnostic criterion value exceeding 1.15, the presence of a pathological process is ascertained.

EFFECT: invention can be used to diagnose age-related macular degeneration of the retina.

5 cl, 5 dwg

Description

The invention relates to medicine, specifically to ophthalmology, and can be used to detect age-related macular dystrophy of the retina (AMD) in the early preclinical stages of the development of the disease, when the clinical symptoms of the disease are not yet manifested.

According to WHO [Ophthalmology. 2000. V. 107. P. 2224-2232], AMD is a leading cause of blindness in developed countries and ranks third among the causes of blindness in the second half of life after glaucoma and diabetic retinopathy. From loss of central vision affects more than 30% of the population over 75 years. The terminal stage of AMD (blindness) occurs in 1.7% of the total population older than 50 years and about 18% of the population older than 85 years. In Russia, the incidence of AMD is 15 people per 1000 population [Libman ES, Shakhova EV Materials of the VII Congress of Ophthalmologists of Russia. 2000. S. 209-214].

The main risk factor for the occurrence of the disease is age, and genetic factors as well as environmental factors, including exposure to light, play an important role. [Ostrovsky M.A. Advances in biological chemistry. 2005.V. 45. S. 173-204]. The development of AMD is accompanied by pathological changes in the retinal pigment epithelium (RPE) and, ultimately, the death of the photoreceptor cells of the retina. Currently, the disease is considered practically incurable, therefore, an important task is to detect AMD as early as possible in order to take timely protective and preventive measures to slow down the development of this severe ocular pathology and maintain a good quality of life for the patient for many years.

The complex of functional diagnostic optical methods for clinical diagnosis of AMD includes registration of autofluorescence (AF) of the fundus, optical coherence tomography (OCT), and fluorescence angiography (FAG). A common drawback of these methods is that they allow you to diagnose pathology at the stage when the clinical signs of the disease are already showing. The FAG method, in addition, is invasive and unsafe for the health of the patient.

Most often, to detect pathological changes in the retina / RPE complex, the fundus AF method is used [Schmitz-Valckenberg S. et al. Perspectives in imaging technologies. In: Holz F.G., Schmitz-Valckenberg S., Spaide R.F., Bird A.C. (eds) Atlas of fundus autofluorescence imaging. Springer-Verlag, Berlin: Springer-Verlag; 2007. P. 331-338]. It is based on the acquisition of an image created mainly by its own fluorescence of the so-called “Old age pigment” - lipofuscin granules (LH), which are formed and accumulate in RPE cells as a result of incomplete lysosomal degradation of phagosomes during aging and especially intensively in the development of degenerative diseases of the retina and RPE. The fluorescence properties of LH are mainly due to the presence of conjugates of fully trans retinal, the so-called bisretinoids - bis-retinylidene ethanolamine (A2E) and others, and the products of their photooxidation and photodegradation [J.R. Sparrow, et al. Prog. Retin. Eye Res. 2012. V. 31. N 2. P. 121-135]. It is shown that the quantitative and qualitative composition of these products changes during the development of pathology [T.V. Feldman, et al. Anal. Bioanal. Chem. 2015, V. 407, N 4, P. 1075-1088 and Wu Y., et al. Proc. Natl. Acad. Sci. 2010, 107: 7275-80].

To register fundus AF, a confocal laser scanning ophthalmoscope is usually used - an HRA-2 retinal analyzer (Heidelberg, Germany) or more affordable fundus cameras (see, for example, [US 7648239 B2, publ. 19.01.2010]), which as shown in [Park SP, et al. Ophthalmic. Surg. Lasers Imaging Retina. 2013, 44 (6): 536-43.], Are only slightly inferior to the HRA-2 retinal analyzer in image contrast. AF in the RPE is excited using laser radiation with a wavelength of 488 nm. The result is the so-called AF image, which is a monochrome image created by fluorescence of chemical compounds (bisretinoids and their photooxidation and photodegradation products) that are part of LH in RPE cells in the long-wavelength region from 500 nm. By way of illustration in FIG. Figure 1 shows AF images of the fundus in norm (a) and, with developed pathology, AMD (b). The fundus image normally looks monotonously gray with black vessels due to AF screening and a black optic nerve disc due to the absence of fluorophores. In the macular region there is an oval zone of a gradual decrease in fluorescence with an almost black foveola, which is due to the higher density of RPE and the presence of macular pigment in it. The presence of fundus AF in the picture with pathological changes (Fig. 1b) of the darker areas corresponding to hypoautofluorescence and lighter areas corresponding to hypeautofluorescence indicates the occurrence of degenerative processes in the retina and RPE.

Thus, fundus AF is one of the most widely used non-invasive methods for the diagnosis of AMD, which allows one to diagnose early phenotypic changes in RPE, which are the precursors of the progression of this pathology. According to the national guidelines for ophthalmology [Ophthalmology: National guidelines. Edited by S. Avetisov, et al. M.: GEOTAR-Media. 2014, 736 pp.] AF fundus examination of the fundus is recommended for assessing the dynamics of the process (or progression) of AMD. It should be noted that the analysis of the fundus AF pattern provides detailed qualitative information that makes it possible to detect pathological zones and differentiate various forms of pathology, but it does not allow a quantitative assessment of the revealed changes. The degree of disease progression is evaluated subjectively by a specialist by comparing the resulting picture with the norm. The method does not allow to detect pathology at an early preclinical stage of the disease, when the clinical symptoms of the disease do not yet appear, and the picture of AF of the fundus is still practically the same. Nevertheless, on the basis of the results of many studies, it has been shown that the AF method needs to be improved in order to expand its diagnostic capabilities in order to obtain more information regarding the diagnosis and prognosis of AMD [Avetisov S.E. et al. Vestnik Ophthalmology. 2009. N 6. p. 37-42].

Currently, attempts are being made to analyze the spectral characteristics of AF in order to use these data for early diagnosis of AMD. So, in the patent [US 6371615 B1, publ. 04.16.2002] and a later work by the same authors [Schweitzer D, et. al. Ophthalmologe. 2009. 106 (8): 714-22] for the early preclinical diagnosis of pathological AMD processes, it is proposed to use a quantitative approach based on the measurement of AF lifetime (attenuation time) (fluorescence lifetime imaging microscopy FLIM). The authors showed that in the short-wavelength range the recorded AF-fundus lifetimes in healthy people are lower than in patients with AMD. Measurements are carried out using a FLIO (fluorescence lifetime imaging ophthalmoscope) ophthalmoscope created on the basis of the well-known confocal laser scanning ophthalmoscope (Heidelberg, Germany), which allows one to obtain well reproducible data on AF lifetime detected in the macula area. Excitation of the fundus AF is carried out by pulses of a picosecond laser with a peak wavelength of 446 nm, after which AF lifetime is detected in two spectral regions of 490-560 nm and 560-700 nm. The obtained experimental kinetic curves are mathematically processed to obtain AF lifetimes in the spectral regions indicated above. According to the authors, this kind of data can be used as a diagnostic parameter that will detect the development of pathology at the earliest stages of its development, when there are no clinical manifestations of the disease. At the same time, it is necessary to note the shortcomings of such an analysis, imposing restrictions on the possibility of its use in practical ophthalmology. To implement the method, which involves the measurement of picosecond time ranges of the AF lifetime, it is necessary to use high-precision expensive ophthalmic equipment, inaccessible for mass use. It is also worth noting that the proposed AF excitation wavelength of 446 nm, in contrast to the 488 nm excitation wavelength used in practice, lies in the spectral region of the absorption of the lens, which may also make it difficult to obtain the necessary data. The reliability of the results obtained is doubtful, since complex experimental kinetic dependences, which reflect the aggregate AF contributions of a large number of fluorophores contained in PH and other eye tissues, are approximated by relatively simple two- or three-exponential curves, which does not allow one to obtain a reliable quantitative diagnostic criterion.

As a prototype adopted the method of early diagnosis of AMD, described in the application [US 2003/0004418 A1, publ. 02.01.2003], in which an approach was used based on a comparison of AF intensities in different spectral ranges after exposure to certain parts of the fundus of the eye with a light source with different wavelengths. The method includes exposure to the fundus of the light flux in the wavelength range of 400-490 nm or laser radiation in the wavelength range of 690-900 nm (the description also contains information on UV irradiation at 364 nm) and measurement of the intensity of the excited AF in two different spectral ranges - in the region of 410-530 nm, corresponding to fluorophores of the Bruch and Druze membrane, and in the region of 505-700 nm, corresponding mainly to LH fluorophores in the RPE. Then, the ratio of the AF intensities obtained in different spectral ranges is determined and compared with a predetermined set of values corresponding to the norm. The described method has several disadvantages. The implementation of the method requires the use of complex and expensive equipment that allows you to generate exciting light in different light ranges. Repeated exposure to light during the examination with light of different wavelengths and pulse durations can be uncomfortable and unsafe for the patient. Registration of excited AF and measurement of the compared AF intensities occurs in the ranges corresponding to the AF of a wide range of fluorophores of various nature, localized in various tissues of the eye. This significantly complicates the analysis of the obtained data and does not allow us to identify specific features associated specifically with the development of AMD. The proposed "semi-quantitative" approach to the diagnosis of the disease, based on a comparison of the obtained data with a set of reference values, leaves the possibility of an ambiguous interpretation of the research results.

The technical problem to which the present invention is directed is to develop a method for detecting early preclinical stages of AMD development, which is widely available in practical ophthalmology, based on the use of a spectral quantitative parameter characterizing specific changes in the fundus AF associated with the development of AMD.

The problem is solved by the proposed method for detecting AMD, including light excitation of the AF of the fundus, recording the intensity of the excited AF in the specified spectral ranges and subsequent mathematical processing of the data to obtain a diagnostic criterion, characterized in that for the excitation of the AF using a light signal from a LED with a peak wavelength of 488 nm , the intensity of the excited AF is recorded in the spectral range 1 corresponding to the range 530-580 nm, and in the spectral range 2 corresponding to in the range of 600-650 nm, using mathematical data processing, the values of the integral intensities of the AF signals I ₁ and I ₂ in the spectral ranges 1 and 2, respectively, are obtained, and the diagnostic criterion is calculated as the ratio of I ₁ to I ₂ , while with the value of the diagnostic criterion, exceeding 1.15, ascertain the presence of a pathological process.

The following is a list and description of the drawings, explaining the invention:

FIG. 1. The AF pattern of the fundus is normal (a) and with AMD (b). Photos courtesy of FGU MNTK Eye Microsurgery named after Acad. S.N. Fedorova Rosmedtehnologii ".

FIG. 2. Fluorescence spectra of RPE cell suspensions (above) and HPLC analysis of chloroform extracts of fluorophores contained in these suspensions (below) for donors aged 59 years (“normal” and “pathology”). The wavelength of the exciting light is 488 nm. The spectra are normalized at a wavelength of 592 nm. The spectrum indicated by "n" corresponds to the norm, "p" - pathology. In the chromatograms, the peaks in region 1 correspond to the products of photooxidation and photodegradation of bisretinoids (fluorophores), the peaks in region 2 correspond to A2E (bis-retinylidene ethanolamine) and its isomeric forms.

FIG. 3. Averaged fluorescence spectra of RPE cell suspensions obtained from cadaver eyes of donors of different ages in the “normal” (n = 10) and “pathology” groups (n = 7). The wavelength of the exciting light is 488 nm. The spectra are normalized at a wavelength of 592 nm.

FIG. 4. Fluorescence spectra of RPE cell suspensions from cadaver eyes of donors aged 59 years (“normal” and “pathology”) with spectral ranges I ₁ (530-580 nm) and I ₂ (600-650 nm) used to obtain diagnostic criterion K.

FIG. 5. The block diagram (A) and the schematic optical diagram (B) of the device for implementing the inventive method.

1 - Eye lens;

2 - Beam splitter;

3 - Depicting block;

3.1 - Intermediate lens;

3.2 - Imaging lens;

4 - Dichroic beam splitter;

5 - Image sensor range 1;

6 - image sensor range 2;

7 - Lighting unit;

7.1 - Light source, including a blue range LED;

7.2 - Capacitor;

7.3 - Dichroic beam splitter;

7.4 - Imaging lens of a lighting system;

7.5 - Fiber optic tow;

7.6 - Projection system;

7.7 - IR LED;

7.8 - Capacitor.

F - Spectral Filter

M - Aperture

The proposed method is based on the results of many years of research by the authors on a comparative spectral analysis of fluorophores in LH from RPE cells isolated from cadaver eyes corresponding to the “norm” (absence of intravital ophthalmic disease) and pathology (the presence of clinical signs of intravital AMD). The experiments were performed on cadaveric eyes in accordance with the Law of the Russian Federation of December 22, 1992 N 4180-1 “On transplantation of organs and (or) human tissues” with amendments and additions of June 20, 2000, October 16, 2006, February 9 , November 29, 2007, May 23, 2016. Before the start of the experiment, each eye was carefully examined by an ophthalmologist to determine if there are clinical signs of AMD ("pathology") or lack thereof ("norm") in the fundus.

We studied samples of RPE cell suspension obtained from the individual cadaver eyes of two groups of donors: the “norm” group included 10 samples obtained from donors aged 27-68 years who did not have ophthalmic diseases during their lifetime, the “pathology” group included 7 samples obtained from donors aged 59-88 years who suffered during the life of AMD. In FIG. Figure 2 shows, by way of example, the fluorescence spectra of RPE cell suspensions and determined by HPLC analysis, the compositions of chloroform extracts of fluorophores from these suspensions obtained from cadaver eyes from donors aged 59 years corresponding to “normal” and “pathology”. It can be seen from the figure that, regardless of the age of the donors, the fluorescence spectra are of the same nature and contain two characteristic bands with maxima in the regions of 556 and 592 nm. In the spectra corresponding to the “norm”, the maximum at 592 nm is more pronounced, and at the wavelength of 556 nm, a shoulder is observed. In the spectra of samples obtained from donors with intravital AMD (“pathology”), the maximum is more pronounced at 556 nm and less at 592 nm. In other words, in the case of “pathology,” an increase in the band intensity is observed in the region of 556 nm, which indicates the accumulation in the LH of the products of photooxidation and photodegradation of bisretinoids, whose fluorescence spectra are shifted to a shorter wavelength region compared to bisretinoids [Feldman et al, Anal. Bioanal. Chem. 2015, V. 407, N 4, P. 1075-1088]. This is also indicated in FIG. 2 HPLC analysis of samples corresponding to the “norm” and “pathology”. Comparative HPLC analysis of chloroform extracts shows significant differences in the quantitative and qualitative composition of the products in the samples obtained from cadaver eyes without pathology and with visually observed signs of AMD. In the presence of “pathology”, the set of peaks in region 1 is more diverse, while an increase in their relative content is observed in comparison with the “norm”.

In FIG. Figure 3 compares the averaged, normalized at a wavelength of 592 nm, fluorescence spectra of RPE cell suspension samples for the “normal” and “pathology” groups obtained from donors of different ages. Spectra were obtained by averaging the individual fluorescence spectra of RPE cell suspension samples obtained from each cadaver eye, indicating the standard deviation at each point in the spectrum. It can be seen from the figure that in the absence of pathology (the “norm”), the averaged AF spectrum has a pronounced maximum in the region of 592 nm and a shoulder at 556 nm, whereas in the averaged fluorescence spectrum characterizing the “pathology”, the band in the region of 556 nm has a higher intensity in comparison with the "norm". When normalizing all spectra at a wavelength of 592 nm, it becomes obvious that for the pathology group, the fluorescence intensity in the range of 530-580 nm increases markedly, and decreases in the spectral range of 600-650 nm. The observed change in the fluorescence spectrum indicates the accumulation of products of photooxidation and photodegradation of LH bisretinoids, which is an indicator of the development of the pathological process [T.V. Feldman, M.A. et. al. Anal. Bioanal. Chem. 2015. V. 407, N 4, P. 1075-1088]. It should be noted that these products are also strong fluorophores and exhibit phototoxic properties. The increased content of the products of photooxidation and photodegradation of bisretinoids in LH indicates that the organs of vision of the donor were exposed to intense light, which resulted in the accumulation of these products. It is important to take into account the fact that, along with photooxidation and photodegradation of bisretinoids, the formation of reactive oxygen species occurs, which, as you know, can lead to lipid peroxidation and damage to cellular structures. All these processes together initiate or exacerbate the progression of AMD and gradually from the preclinical phase, when the disease is not yet detected either in the AF pattern or in the subjective sensations of the patient, goes to the stage of death of retinal cells and RPE, leading to blindness. The consequences of such processes accumulate gradually: over time, the formation of the products of photooxidation and photodegradation of bisretinoids already contributes to the spectral pattern of AF of the fundus, demonstrating the changes in spectral characteristics shown above, while the clinical signs of the presence of these degenerative processes will appear later.

The results obtained in the study of samples corresponding to both the “norm” and the “pathology” showed that the patterns of change in the quantitative and qualitative composition of fluorophores, as well as their spectral characteristics, are practically independent of the age of the donors, but are determined only by the presence or absence of pathological changes in RPEs, they have characteristic, well reproducible features that can be used as an experimental basis for developing a diagnostic sign of pathology. A change in the AF spectra due to the presence of the products of photooxidation and photodegradation of bisretinoids in PH can be a diagnostic sign of the presence of an early preclinical stage of the disease.

According to the claimed method, a quantitative parameter K, characterizing the difference between the AF spectrum of the fundus in the presence of pathology from the AF spectrum is normal and accepted by us as a diagnostic criterion, is determined by the ratio

where I ₁ is the integral intensity of the AF signal in the range 1 corresponding to wavelengths of 530-580 nm, I ₂ is the integral intensity of the AF signal in the range 2 corresponding to wavelengths of 600-650 nm (Fig. 4), i.e. in those spectral ranges in which the maximum differences in fluorescence intensity are observed for the “normal” and “pathology” groups.

The integral values in the spectral ranges 1 and 2 in the context of this description understand the following values:

where x, y are the coordinates of the points on the fundus (or in the fundus image) within a given region Ω.

The analysis of experimental data shows that for the group "norm"

while for the pathology group

Thus, the “norm” and “pathology” groups are quite separable according to this criterion, which we propose to use as a quantitative diagnostic sign characterizing the presence of a pathological process: the K value obtained during examination of the patient, exceeding 1.15, indicates the presence of AMD.

In contrast to the currently used AF registration method, in which the diagnosis of AMD is made on the basis of subjectively determined qualitative differences in the patient’s AF picture and the AF picture corresponding to the averaged norm (Fig. 1), our proposed criterion is objective quantitative. Moreover, due to the high sensitivity of the used spectral analysis methods, the value of the diagnostic criterion K in excess of 1.15 may indicate the presence of such an early stage of the disease when not only the clinical symptoms do not appear, but the visual picture of AF is still practically the same.

Significant differences of the proposed method from the prototype are as follows.

1. According to the prototype for the excitation of AF of the fundus tissue using light exposure with various spectral characteristics - from UV (364 nm) to pulsed laser IR radiation in the range of 690-900 nm. The implementation of the method requires the use of complex and expensive equipment that allows you to generate exciting light in different light ranges. Repeated exposure to light during the examination with light of different wavelengths and pulse durations can be uncomfortable and unsafe for the patient. In contrast to the prototype, the present invention uses only exciting light LED with a peak wavelength of 488 nm, which allows examination using conventional, affordable for mass use ophthalmic equipment in a patient-friendly mode, assuming a single millisecond (duration from 1 ms to 200 ms) pulsed light exposure on the eye. In this case, it is possible to detect changes in the AF intensity in certain spectral ranges associated with the accumulation of specific products in the RPE that indicate the development of AMD. The use of an LED light source avoids speckle modulation, interference artifacts, which can lead to uneven illumination of the fundus. According to the prototype, the registration of excited AF and measurement of the compared AF intensities takes place in the wavelength ranges of 410-530 nm and 505-710 nm, corresponding to AF of a wide range of fluorophores of various nature, localized in various tissues of the eye. This significantly complicates the analysis of the data and does not allow to identify specific features associated with the development of AMD. The present invention, based on a study of the finer spectral features of AF in the range of 530-650 nm, can improve the reliability of detection of AMD, since it is in this spectral range that quantitative and qualitative differences in AF signals are manifested due to the accumulation in the RPE of specific products accompanying the development of AMD .

2. In contrast to the prototype, the proposed method for detecting AMD is based on the use of a specific quantitative parameter characterizing the ratio of the AF intensity of the products of photooxidation and photodegradation of bisretinoids contained in RPEs in those narrow spectral regions in which the differences between the “norm” and “pathology” are manifested in the maximum degrees. This allows you to get a reliable objective result of the examination of the patient, not depending on subjective factors and previous experience of the examining specialist.

To implement the method, simple equipment available for mass use can be used, for example, a standard fundus camera with a light source modernized as described below and equipped with an additional unit that allows the detection of AF signals in different spectral ranges of 530-580 nm and 600- 650 nm, corresponding to ranges 1 and 2, in which the maximum differences in AF signals for "normal" and "pathology" are observed (see Fig. 4).

In FIG. 5 shows a block diagram A and a schematic optical diagram B of a device that allows implementing the proposed method. Elements 1-3 and 7 correspond to the device of a conventional fundus camera, which allows to obtain a high-quality AF picture of the fundus. The eye lens 1 is located between the eye and the beam splitter 2 connected to the imaging unit 3 containing the intermediate lens 3.1 and the imaging lens 3.2. An additional unit includes a dichroic beam splitter 4, intended for spectral separation of images, and two image sensors 5 and 6, which allow independently or simultaneously detecting signals in different spectral ranges. It is advisable to use matrix photodetectors as an image sensor. To ensure the mechanical strength of the structure, elements 4-6 can be combined into a monoblock. The device is equipped with a lighting unit 7, including a 7.1 light source, which can be used various narrow-band or wide-band light sources equipped with pass filters to obtain a spectral range of 480-490 nm, a condenser 7.2, a dichroic beam splitter 7.3, depicting the lens of the lighting system 7.4, fiber optic tourniquet 7.5 and projection system 7.6.

As a light source 7.1. it is advisable to use a high-efficiency LED source, for example, sources with the Royal Blue and Blue spectra (430-530 nm). The spectrum of the Royal Blue type is characterized by a higher efficiency of fluorescence excitation, however, with significant aging of the lens, the spectral components characteristic of the lens can be strongly absorbed by it. The choice of a particular source of exciting light depends on the age section of the diagnosed patients. An example of commercially available sources of this type are XLamp® XQ-E LEDs manufactured by Сrее (USA). These sources can emit up to 1 W of light power at a control current of 800 mA, which is more than enough to excite AF even taking into account losses in the forming optics.

The device operates as follows: the radiation of LED 7.1 is collected by the capacitor 7.2 and enters the dichroic beam splitter 7.3 in the form of a quasi-parallel beam splitter, where it is completely reflected by the dividing face and sent to the imaging lens of the lighting system 7.4, the purpose of which is to combine the angular and linear dimensions of the source image with the parameters of the input receiver apertures of fiberglass tow 7.5. Fiberglass tow 7.5. serves to transport radiation from a light source 7.1. to the optical module of the device and converting its aperture from circular to circular, as shown in FIG. 5 B. It should be noted that the use of a fiberglass bundle is not mandatory, and the lighting system can be placed directly in the optical module. In this case, an annular diaphragm M should be installed in the focal plane of the lens 7.4. The projection system 7.6 creates an image of an annular luminous aperture (output end of the fiber optic bundle 7.5 or diaphragm M) in the plane of the beam splitter 2, which is made in the form of a mirror with a hole in such a way that the light radiation reflected from the mirror surface, and the central hole is used for observation. This makes it possible to implement the principle of pupil separation, which assumes that the pupil for lighting does not overlap with the pupil of observation in the device’s design, which allows to obtain a high-quality image of the retina, free from the interfering effects of glare from the cornea and lenses of the optical system. It should be noted that the implementation of the principle of geometric pupil separation is a useful option that improves the operational characteristics of the device, however, when observing AF RPE, geometric pupil separation is not necessary, since glare from the exciting radiation is effectively suppressed by spectral filters F. In this case, the beam splitter 2 can be performed in in the form of a dichroic mirror reflecting radiation with a wavelength of up to 500 nm and transmitting radiation of ranges 1 and 2. In this case, the converted e aperture optical fibers and application of a tourniquet 7.5 M aperture and thereby make the design more simple and cheap.

To ensure the comfort of patients undergoing examination, the initial guidance of the device should be carried out on invisible infrared radiation. For this purpose, the device is equipped with an IR LED 7.7, emitting, preferably in the range of 740-850 nm, and a capacitor 7.8. A dichroic beam splitter 4 must transmit radiation in the range of 740-850 nm to a matrix photodetector 6, while the image recorded by the detector is visualized on a video monitor (not shown in the diagram) and used by the operator to direct - focus and align the input pupil of the device with the pupil of the subject's eye.

The eye lens 1 creates an image of the illuminated annular aperture in the plane of the pupil of the studied eye, which ensures uniform illumination of the fundus. An image of the fundus is constructed between the lens 1 and the beam splitter 2. The intermediate lens 3.1 transfers this image with the necessary magnification to the intermediate plane in front of the lens 3.2, which serves to project the image of the eye day in the required scale on image sensors 5 and 6. Spectral separation of the images in spectral ranges 1 and 2 are produced by a dichroic beam splitter 4. As image sensors (photodetector arrays), common CCDs or CMOS m can be used Image sensors, such as an IMX174 sensor manufactured by SONY (Japan). Image sensors are arranged so that each resolution element of the picture I ₁ (x, y) corresponds to a resolution element I ₂ (x, y). Typically, one optical resolution element corresponds to 2-4 pixels of a matrix detector. With an IMX174 sensor pixel size of 5.8 μm, the required accuracy of combining image elements on image sensors 5 and 6 is 10-20 μm, which is quite achievable at the current level of technology development. If necessary, additional alignment correction is possible using digital image processing methods.

To simplify the design of the dichroic beam splitter 4 in the circuit, it is advisable to use a colored glass pre-filter F, which transmits radiation in the ranges 1 and 2 and absorbs in the range 480-490 nm, for example, the ZhS17 filter.

The invention is as follows.

After completion of the guidance process described above, the 7.7 IR LED is turned off and the 7.1 LED is turned on for a period of 1 to 200 ms. The exposure duration is selected by the operator based on the brightness and contrast of the recorded images, and depends on the angular field of view of the instrument, the transparency of the media of the eye being examined, and other factors. The study can be carried out in the mode of simultaneous or alternate recording by the image sensors of AF intensity in the ranges 1 and 2. In the first embodiment, at the time of exposure, both sensors simultaneously synchronize the fundus AF signals in the corresponding spectral ranges 1 and 2. In the second embodiment, the registration takes place alternately, i.e. with one exposure of the fundus, an image in the spectral range 1 is obtained, and with the second in the spectral range 2. This option is less comfortable for the subject, because involves a double light exposure. In addition, there are technical problems associated with the mobility of the eye, as a result of which relative biases will occur in the two images recorded alternately. For an exact comparison of the resolution elements I ₁ (x, y) and I ₂ (x, y), a rather complicated mathematical processing is required. In addition, when the eye is shifted, partial illumination of the backlight radiation by the pupil of the eye may occur, which will affect the backlight intensity and introduce distortions into the calculated values. Thus, the option of conducting research with simultaneous registration of images in the spectral ranges 1 and 2 is preferred.

дает величину диагностического критерия К. При значениях К выше 1,15, констатируют наличие патологического процесса развития ВМД даже в случае отсутствия клинических признаков заболевания, таких как детектируемое изменение картины АФ глазного дна или субъективных жалоб пациента.The registered signals are sent to a computer, where they are digitally processed to obtain the values of I ₁ and I _2. The calculation algorithm is based on the dependence of the AF signal intensity on the detection wavelength in a given region of the fundus Ω taking into account the above relations (2) and (3) . The ratio of the obtained values

gives the value of the diagnostic criterion K. At values of K above 1.15, the presence of the pathological process of AMD development is noted even in the absence of clinical signs of the disease, such as a detectable change in the AF pattern of the fundus or subjective complaints of the patient.

Claims (5)

1. A method for diagnosing age-related macular dystrophy of the retina, including light excitation of autofluorescence autofluorescence of the fundus, recording the intensity of excited autofluorescence in the given spectral ranges and subsequent mathematical processing of the data to obtain a diagnostic criterion, characterized in that for the excitation of autofluorescence, a light signal of 48 LEDs with a peak of 8 is used nm, the intensity of the excited autofluorescence in the spectral region 1 corresponding to pazonu 530-580 nm and in the spectral region 2 corresponding to the range of 600-650 nm, using a mathematical treatment, the values of integrated autofluorescence signal intensities I ₁ and I ₂ in the spectral regions 1 and 2 respectively, and the diagnostic criteria was calculated as the ratio of I ₁ to I ₂ , while with the value of the diagnostic criterion exceeding 1.15, the presence of a pathological process is noted. 2. The method according to p. 1, characterized in that for its implementation use a fundus camera equipped with a dichroic photo-splitter and two image sensors recording autofluorescence in regions 1 and 2, respectively. 3. The method according to p. 2, characterized in that the image sensors record autofluorescence in regions 1 and 2 at the same time. 4. The method according to p. 2, characterized in that the image sensors record autofluorescence in regions 1 and 2 alternately. 5. The method according to PP. 2-4, characterized in that the image sensors use matrix photodetectors.

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