[Structural and functional features of the eye in Marfan syndrome. Report 2. Changes in the anatomical complex of the lens]. / Strukturno-funktsional'nye osobennosti glaza pri sindrome Marfana. Soobshchenie 2. Izmeneniya anatomicheskogo kompleksa khrustalika.

Analysis of lens changes in Marfan syndrome (MS), in addition to assessing the position of the lens itself, should include the possibility of examining its supporting and accommodative components (ciliary zonule and ciliary body), or what can be called the entire anatomical complex of the lens. Optical methods of studying the structures of the anterior segment of the eye, due to iris opacity, allow only to analyze the state of the lens within the natural or medically enlarged pupil width. Visualization of the structures located behind the iris is possible with the use of radiation diagnostic methods, in particular ultrasound biomicroscopy (UBM). PURPOSE: This study assesses the state of the anatomical complex of the lens in MS using UBM. MATERIAL AND METHODS: The study was carried out on clinical material previously used by us to analyze changes in the fibrous membrane of the eye in MS. At the first stage, the main (19 patients with MS, 38 eyes) and the control (24 patients with myopia, 48 eyes) groups were formed for comparative evaluation. The formed groups were standardized according to the age of the patients and the axial length of the eye. At the second stage, patients with MS were divided into subgroups depending on the absence or presence of biomicroscopic signs of ectopia lentis (22 and 16 eyes, respectively). For UBM, an ultrasound linear sensor with a scanning frequency of 50 MHz was used (Aviso device, Quantel Medical, France). Various biometric UBM indicators were determined: lens thickness, diameter of the lens, lens-axial length factor, iris-lens angle, iris-lens contact distance, posterior chamber depth, length of the fibers of ciliary zonule, thickness of the ciliary body, sclera-ciliary process angle. RESULTS: There are changes in the anatomical complex of the lens as a whole in MS (in the lens itself, the ciliary zonule, and the ciliary body), which are characterized by an increase in lens thickness and a decrease in the diameter of the lens, an increase in the length of the fibers of the ciliary zonule and a decrease in the thickness of the ciliary body. At the same time, the displacement of the lens detected by optical biomicroscopy (ectopia lentis) can be considered as an advanced stage of changes in the anatomical complex of the lens. CONCLUSION: UBM provides the possibility of full-fledged visualization of all components of the anatomical complex of the lens in terms of both diagnostics, and monitoring of changes in MS. The question of the advisability of including this method in the algorithm for diagnosing ocular manifestations in order to verify the MS remains open. Possible obstacles may be, on the one hand, related to the need for special and expensive equipment, and on the other hand, the absence of a generally accepted «normal¼ values of UBM indicators of the anatomical complex of the lens.

[Structural and functional features of the eye in Marfan syndrome. Report 1. Changes in the fibrous tunic of the eye]. / Strukturno-funktsional'nye osobennosti glaza pri sindrome Marfana. Soobshchenie 1. Izmeneniya fibroznoi obolochki.

Marfan syndrome (MS) is an orphan hereditary connective tissue disease associated with a mutation in the FBN1 gene, which pathological manifestations are characterized by polysystemic involvement. The fibrillin-1 protein is an integral component of the sclera and cornea of the eye, and in MS its structure is distrubed. PURPOSE: This study assesses potential structural and functional changes in the cornea and sclera of a patient with MS. MATERIAL AND METHODS: Two groups were formed, comparable in the axial length of the eye and age: the main group - 19 patients (38 eyes) with a verified diagnosis of MS, and the control group - 24 patients (48 eyes) with myopia of varying degrees. The results obtained from MS patients were analyzed depending on the absence or presence of ectopia lentis. In addition to measuring the basic ophthalmological parameters (refraction, axial length, visual acuity), topographic keratometry, anterior segment optical coherence tomography, and ocular response analyzer were used for structural and functional assessment of the cornea and sclera. RESULTS: In MS there was a statistically significant increase in the radius of curvature and a decrease in corneal refraction in the central zone compared to the control group. There were no significant differences in central corneal thickness, but there was a significant decrease in the thickness of the sclera in the limbal zone compared to the control group. There were no statistically significant changes in corneal hysteresis and corneal resistance factor in MS. CONCLUSION: This study confirmed the previously obtained data on the tendency of the optical power to reliably decrease in MS (flattening of the cornea). This symptom can be considered as a compensatory factor affecting clinical refraction, while the decrease in the thickness of the sclera - as the main reason for aaxial length elongation in MS. There were no clear patterns of dependence of the changes in the cornea and sclera analyzed in this study on the presence or absence of ectopia lentis. Changes in the lens, perhaps, should be regarded only as one of the potential components of the ocular symptom complex in MS.

[The effect of keratoconus-associated refractive errors on the results of tomographic methods of studying the posterior structures of the eye]. / Vliyanie opticheskikh narushenii pri keratokonuse na rezul'taty tomograficheskikh metodov issledovaniya struktur zadnego segmenta glaza.

PURPOSE: The study assesses the potential influence of refractive errors in keratoconus (KC) on the results of tomographic methods of studying the structures of the posterior eye segment. MATERIAL AND METHODS: The study included 30 patients with bilateral stabilized KC of stages I-IV in classification by M. Amsler. Spherical and cylindrical components of refractions were determined using automatic refractometry, keratometry measurements - based on scanning keratotopography with Scheimpflug analyzer. Aberrometry was performed to evaluate corneal wave front according to the following parameters: root mean square for lower order aberrations (RMS LOA), root mean square for higher order aberrations (RMS HOA), vertical trefoil, vertical coma, horizontal coma and spherical aberrations. Optical coherence tomography (OCT) and laser confocal scanning ophthalmoscopy (HRT 3) data was used in morphometric analysis of the optic nerve head and peripapillary retina. The following morphometric parameters were analyzed: optic nerve head (ONH) area, optic disc cup area, optic disc cup volume, ratio of optic disc cup area to ONH area, neuroretinal rim area, neuroretinal rim volume, peripapillary retinal nerve fiber layer (RNFL) thickness. All studies were performed first without correction, and 30 minutes after installing customized scleral hard contact lenses (SHCL). RESULTS: Compensation of the refractive errors characteristic for KC was achieved as expected with contact correction. OCT revealed a general trend for reduction in the area and volume of the optic disc cupping, ratio of area to volume of the optic disc cupping, as well as an increase in other parameters. As such, with correction the values for area and volume of the neuroretinal rim according to OCT were 2.2 and 13%, HRT 3 - 18 and 51.6%; comparable increase in mean RNFL thickness - 2.8 and 28.5%, respectively (p<0.001). According to HRT 3 data, the area and volume of optic disc cupping statistically significantly decreased (by 21 and 28%, respectively), while OCT showed statistically significant decrease only in cupping area (by 5.7%). The ratio of cupping to ONH area decreased by 6.6 and 23% relative to the initial data obtained with OCT and HRT 3, respectively. Significant decrease in ONH area amid SHCL correction was observed only with HRT 3. The revealed changes in morphometric parameters were analyzed using the fundamental principles of physiological optics. Changes in interference pattern and, consequently, morphometric parameters of structures of the eye fundus in KC are of multifactorial nature, and are mostly associated with refractive and wave artefacts occurring when the rays pass through the irregular corneal surface and cannot be optically compensated by the device. The use of SHCL as means for making the optic system relatively regular can significantly decrease the artefacts in morphometric measurements. CONCLUSION: The results obtained in this study demonstrate the practicality of tomographic examination in KC with contact correction. The optimal choice is custom-fit SHCL, which along with proper correction of refractive errors also ensures stable position of the lens on the cornea. In standard examination specialists should take into account the «false¼ decrease in parameters of the peripapillary retinal nerve fiber layer and increase in ONH cupping.

[Endocapsular fixation of intraocular lens in patients with ectopia lentis and Marfan syndrome (case study)]. / Endokapsulyarnaya fiksatsiya intraokulyarnoi linzy pri ektopii khrustalika na fone sindroma Marfana (klinicheskoe nablyudenie).

Modern trends in advancement of phaco surgery techniques in patients with ectopia lentis (including patients with Marfan syndrome) are characterized by the transition from complete removal of the lens (lensectomy) to aspiration of the lens substance and attempts to preserve and reposition the capsular bag. This case study analyzes the results of surgical treatment of bilateral ectopia lentis in a 6-year-old patient with Marfan syndrome. The specifics of microinvasive phaco surgery consisted in capsular bag preservation and endocapsular fixation of the intraocular lens. The article presents the results of ophthalmological observation over a seven-year period.

[Contribution of Academician M.M. Krasnov to ophthalmological science and practice]. / Vklad akademika M.M. Krasnova v oftal'mologicheskuyu nauku i praktiku.

The scientific legacy of Professor Mikhail Mikhailovich Krasnov, Academician of the Russian Academy of Medical Sciences, is large and multifaceted. His name is associated with the whole epoch of establishment and development of new methods of diagnostics and treatment of eye diseases. The representative of the dynasty of ophthalmologists M.M. Krasnov is the author of more than 350 scientific works, 80 inventor's certificates and 40 foreign patents.

[Keratoconus: main lines of research]. / Keratokonus: osnovnye napravleniya issledovanii.

Keratoconus (KC) research focuses on studying pathogenesis, advancing diagnostic techniques and methods of correction and treatment. The working hypothesis for KC etiopathogenesis is based on abnormalities in distribution of microelements in the cornea and its potential influence on the processes of stromal collagen disorganization. Improvement of early diagnosis of KC is associated with evaluation of microstructural changes in the cornea using computerized methods such as Scheimpflug camera and high-definition optical methods for visualization of initial signs of a pigment ring. The main optimization directions of KC contact correction are associated with increasing gas permeability of the material, improving lens design and methods of lens fitting. Customized fitting of gas-permeable scleral hard contact lenses with consideration of topographic features of the anterior corneal surface allows achieving stable lens positioning and preserving the tear gap between the lens and the cornea. Alternative methods of correcting the refraction component of KC are associated with surgical interventions involving increase in corneal volume in the paracentral area. Implantation of corneal ring segments should be considered as an alternative to correction of refractive errors in cases with unsatisfactory individual subjective tolerance and insufficient patient compliance with contact correction. Femtolaser-assisted implantation of intrastromal allotransplants along with a decrease in the degree of spherical and astigmatic components of refractive errors contribute to prevention of KC progression. Advancement of techniques of corneal collagen cross-linking for prevention of KC progression is aimed at reducing the risk of developing post-operative complications directly related to the extent of intraoperative deepithelization. Limiting corneal ectatic area by implantation of intrastromal allotransplants can be considered an alternative approach. Deep anterior lamellar keratoplasty and penetrating keratoplasty are the surgeries of choice in replacing altered corneal layers in KC. With regard to the modern trends in selective keratoplasty, selective replacement of the cornea in lamellar keratoplasty reduces the rate of injuries and the risk of tissue reaction.

[Hybrid (femtolaser) phacoemulsification: technical aspects and functional results]. / Gibridnaya (femtolazernaya) fakoemul'sifikatsiya: tekhnologicheskie aspekty i funktsional'nye rezul'taty.

This article summarizes scientific and practical results of hybrid femtosecond laser-assisted phacoemulsification (HFE) including study of clinical and technical aspects of the intervention and evaluation of post-surgical functional state of the eye on the basis of clinical, morphological and biomechanical data. The HFE technology should be considered the method of choice for microinvasive phaco surgery, its main advantage being the possibility of controlled handling of such important surgical stages as anterior circular continuous capsulorhexis and nucleus fragmentation on a closed eyeball, which significantly reduces the risk of complications and decreases of effective ultrasound time.

[Confocal microscopy of the corneal nerve fibers]. / Konfokal'naya mikroskopiya nervnykh volokon rogovitsy.

This article presents the results of confocal microscopy of the corneal nerve fibers (CNF). The transparency of the cornea provides a unique potential for in vivo visualization of thin unmyelinated nerve fibers at the level close to morphological study. Modern software eliminates the need for manual tracing of the confocal image fragments, allows objectifying the process of assessment of CNF structure based on quantitative indicators characterizing the length, density and tortuosity of the main nerve trunks. Clinical application of structural analysis of the CNF has two potential directions associated with immediate tasks of ophthalmology, as well as with interdisciplinary affairs. In terms of ophthalmology, this primarily concerns various surgical interventions potentially affecting the state of the cornea, and chronic pathological processes in the cornea of different nature. Such studies could analyze the degree of changes in the CNF, or the particularities of corneal reinnervation. The potential for interdisciplinary studies lies in using CNF as biomarkers of systemic polyneuropathies. Relative simplicity, high level of direct visualization of the thin nerve fibers, and the obtained results allow recommending corneal confocal microscopy as a tool for primary screening and consequent monitoring of neuropathies in addition to the conventional methods.

[Modern achievements in the diagnosis and treatment of glaucoma]. / Sovremennye dostizheniya v diagnostike i lechenii glaukomy.

Glaucoma is one of the most difficult and significant ocular conditions. The chronic asymptomatic course of glaucoma progression leads to irreversible deterioration of visual functions. Many aspects of its pathogenesis, the features of its clinical presentation, diagnosis and treatment have been identified in recent years. The results of diagnostic methods: tonometry, perimetry, optical coherence tomography - with glaucoma do not have high specificity due to the large diversity of the population. When determining the target intraocular pressure (IOP), we look at the indicators of the choroidal blood flow and biomechanical stress of the cornea and sclera (fibrous membrane of the eye). Studying visual functions is important in the diagnosis and monitoring of glaucoma. The creation of a modern portable device based on a virtual reality helmet allows examination of patients with low central vision. Structural changes in glaucoma affect the optic disc and the inner retinal layers. The proposed classification of atypical discs allows determining the earliest characteristic changes in the neuroretinal rim for glaucoma in cases of difficult diagnosis. The complexity of the diagnosis of glaucoma is also associated with concomitant pathologies in elderly patients. In cases with comorbidity of primary glaucoma and Alzheimer's disease the structural and functional changes revealed by modern research methods for glaucoma are explained by both the process of secondary transsynaptic degeneration and the death of neurons as a result of an increased IOP. The starting treatment is and its type are fundamentally important for preserving visual functions. Drug therapy with prostaglandin analogues contributes to a significant and persistent decrease in the level of IOP, and mainly by utilizing the uveoscleral outflow pathway. Surgical treatment of glaucoma is an effective way to achieve the target IOP values. However, postoperative hypotension affects the bloodstream both in the central and peripapillary retina. Optical coherence tomography angiography helped establishe that the strongest factor that determines postoperative changes is the difference in IOP, not its absolute level.

[Adding to the results of the discussion on the need to separately designate the pre-Descemet's layer in the corneal structure]. / K itogam diskussii o neobkhodimosti vydeleniya predestsemetovogo sloya v strukture rogovitsy.

The article summarizes the outcomes of the discussion concerning the need to designate the pre-Descemet's layer (PDL) in the cornea as a separate anatomical structure. Considering the differences in opinions on this highly debated topic, various studies suggested a compromised, purely terminological solution - to limitedly separate the PDL as a deep stromal layer of the cornea.

[Effect of conventional and orthokeratological hard contact lenses on anatomical and functional characteristics of the cornea]. / Vliyanie traditsionnykh i ortokeratologicheskikh zhestkikh kontaktnykh linz na anatomo-funktsional'noe sostoyanie rogovitsy.

Contact lenses are widely used for correction of myopia due to their accessibility, effectiveness and relative safety. PURPOSE: This study evaluated the potential effects of conventional hard contact lenses (HCL) and orthokeratological contact lenses (OKL) on anatomical and functional condition of the cornea in myopia correction. MATERIAL AND METHODS: The study included 80 patients (159 eyes) with low, moderate and high myopia. Group 1 consisted of 40 patients (79 eyes) who used conventional HCL; group 2 included 40 patients (80 eyes) who used OKL. All patients underwent topographic keratometry, corneal pachymetry mapping (Pentacam, Oculus, Germany; Visante OCT, Carl Zeiss, Germany), high-order aberrometry (OPD Scan, Nidek, Japan), confocal microscopy (Confoscan 4, Nidek, Japan), evaluation of corneal biomechanical properties (ORA, Reichert Technologies, USA) and corneal light scattering (Pentacam, Oculus, Germany). Examinations were taken before the treatment started and after 8-12 months of contact lens wear. RESULTS: Group 1 showed corneal thickness increase in all zones (by 0.9-1.1%), no significant changes in corneal refraction, and increase in corneal hysteresis and corneal resistance factor. OKL wear led to a significant flattening of anterior surface of the cornea and steepening of its paracentral area, decrease in central corneal thickness (by 2.8%) and increase in mid-peripheral thickness (by 2.2%). No significant changes in posterior corneal surface were observed in the study patients. More significant increase in higher-order aberrations and the degree of light scattering was observed in group 2, while changes in subepithelial nerve plexus and stromal structure were more significant in group 1. CONCLUSION: Long-term OKL wear shows more significant morphological and functional corneal changes compared to RGP lens.

[Features of accumulation of chemical elements in the volume of the lens in senile cataract]. / Osobennosti nakopleniya khimicheskikh elementov v ob"eme khrustalika pri senil'noi katarakte.

PURPOSE: This study provides a detailed analysis of the bioinorganic chemical composition of lens substance in patients with senile cataract using classical and spatial statistics methods. MATERIAL AND METHODS: The study included 30 isolated human lenses. The light scattering ability (LSA) of the lens substance was evaluated using an original method. Additionally, distribution of chemical elements in the lens substance was analyzed using a scanning electron microscope with energy dispersive spectrometer (SEM/EDS). Measurements by all methods were carried out in a single coordinate space, which made it possible to compare the spatial correlation of different parameters. RESULTS: Small-angle light scattering of the lens substance has been quantitatively characterized for the first time. In contrast to the conventional norm, in senile cataract the accumulation fields of the majority of ion-forming elements (including Na, P, K, Cl) are distributed along the lines repeating the geometry of the lens capsule. At the same time, the light scattering ability of certain areas of the lens is significantly correlated with changes in the concentrations of Na, P, K, Ca in these areas. In particular, one ion-forming element can be distinguished - Na: spatial change of its concentration in senile cataract is strongly associated with a local change in LSA of the lens with opacities clustering of any degree. Thus, a change in the nature of the Na accumulation in the lens volume can be considered the main marker of senile cataract formation. CONCLUSION: The distribution pattern of ion-forming elements indicates that the loss of barrier properties in the capsule plays a significant role in the development of senile cataract.

[Hereditary ectopia lentis: diagnosis and surgical treatment]. / Nasledstvenno obuslovlennye varianty ektopii khrustalika: diagnostika i khirurgicheskoe lechenie.

This review describes hereditary diseases in which ectopia lentis may be present as one of the symptoms, considers the basic diagnostic concepts of lens disposition, and analyzes the options in surgical treatment of ectopia lentis and optical correction of aphakia.

[Modern prerequisites for creating a collagen-based artificial analogue of the corneal stroma]. / Sovremennye predposylki sozdaniya iskusstvennogo analoga stromy rogovitsy na osnove kollagenovogo materiala.

Despite the fact that various collagen biomaterials have been actively used in ophthalmology for more than 30 years, the problem of creating a material that could replace the donor cornea have not been solved. Recent advances in the field of tissue engineering and regenerative medicine have shifted the focus of approaches to solving the problem of creating an artificial cornea towards laying conditions for the restoration of its specific layers through mechanisms of its own cellular regeneration. In this regard, extracellular matrices based on collagen are gaining popularity. This review discusses general limitations and advantages of collagen for creating an artificial cornea.

[The impact of the position of toric intraocular lenses on the functional outcomes of phaco surgery]. / Vliyanie polozheniya toricheskikh intraokulyarnykh linz na funktsional'nye rezul'taty fakokhirurgii.

The article reviews data on the impact of the position (orientation) of toric intraocular lenses on the functional outcomes of cataract phacoemulsification surgery, discusses the algorithm of astigmatism correction with intraocular lenses including preoperative determination of the size and position of main meridians, calculation of lens parameters, marking of corneal meridians, intraoperative positioning, as well as rotation and/or repositioning of the lens when necessary.

[Long-term outcomes of bandage therapeutic-optical keratoplasty in the treatment of keratoconus]. / Otdalennye rezul'taty bandazhnoi lechebno-opticheskoi keratoplastiki pri lechenii progressiruyushchego keratokonusa.

Intrastromal keratoplasty has recently been widely used in the surgical treatment of keratoconus (KC). In 2013, a new type of interlamellar keratoplasty operation was developed - bandage therapeutic-optical keratoplasty (BTOK). PURPOSE: Evaluation of the long-term outcomes of surgical treatment of stages II and III progressive KC with BTOK technique. MATERIAL AND METHODS: The study included 107 patients (126 eyes): group 1 with stage II KC - 78 eyes, 100% of these patients were observed for 1 year, 52 eyes (66%) for 3 years, and 18 eyes (23%) for 5 years; group 2 - 48 eyes with stage III KC, with 100% of them observed for 1 year, 39 eyes (81%) for 3 years, and 12 eyes (25%) - 5 years. All patients received a customized allograft in the form of an intrastromal corneal ring segment (ICRS). RESULTS: During the first year after BTOK surgery, the uncorrected and corrected visual acuity (UCVA and CVA) in the first group increased by 0.5±0.04 (p<0.05) and 0.2±0.02 (p<0.05), respectively, in the second group - by 0.46±0.05 (p<0.05) and 0.47±0.05 (p<0.05) due to a decrease in refractive indices in the central 3.0 mm zone. In the first group, mean refraction in the central 3.0 mm zone (Km) was within 45±3.75 (p<0.05), in the second - 48.63±.2 diopters (p<0.05), while maximum refraction in the central 3.0 mm zone (Kmax) decreased from 50.02±2.20 (p<0.05) to 44.61±1.03 diopters (p<0.05) in the first group, from 58.21±3.43 (p<0.05) to 50.45±3.46 diopters (p<0.05) in the second group. The values of UCVA, CVA and refractive indices of the central corneal zone in the first and second groups did not change statistically significantly after three and five years. Minimum corneal thickness in the first group increased from 476.23±13.35 to 485.08±15.80 µm (p<0.05), in the second - from 412.73±38.63 to 422.00±42.25 µm (p<0.05). CONCLUSION: BTOK surgery can be used in patients with stages II and III KC to improve the visual functions, strengthen the ectatic cornea and stop the progression of the disease.

[Clinical and morphological characteristics of corneal epithelial dystrophy (clinical observations)]. / Kliniko-morfologicheskie kharakteristiki epitelial'noi distrofii rogovitsy (klinicheskie nablyudeniya).

This paper presents clinical observations that can be regarded as degeneration of the basement membrane of the corneal epithelium. Difficulties in identifying such forms of corneal dystrophies, on the one hand, are associated with limitation and polymorphism of the clinical picture, and, on the other hand, with insufficient information content of the basic diagnostic methods (i.e. the methods used during the initial examination). The presented clinical cases allow singling out the alarming and pathognomonic signs of the disease in the diagnostic algorithm. In the first case, attention should be paid to biomicroscopic changes in the superficial layers of the cornea and the optical defects, which can be regarded as a manifestation of an irregularity of corneal refraction. Identification of pathognomonic signs of the disease is possible on the basis of a detailed, close-to-morphological study of the structure of superficial corneal layers using confocal microscopy and optical coherence tomography. At the same time, the localization of the detected changes at the level of epithelial basement membrane and its basal sections is of crucial significance for substantiating the diagnosis. In addition, according to the literature data, recurrent erosions of the cornea of unclear etiology should be attributed to presumptive signs of degenerative changes in the basement membrane of the epithelium.

[Ocular manifestations of Marfan syndrome]. / Glaznye proyavleniya sindroma Marfana.

Marfan syndrome is an orphan disease that is caused by a mutation in the FBN1 gene located on chromosome 15 (15q21.1) and is usually inherited in an autosomal dominant manner. The article reviews the results of studies concerning the potential ocular manifestations of Marfan syndrome.

[Anatomical, morphological and biomechanical aspects of accommodation]. / Anatomo-morfologicheskie i biomekhanicheskie aspekty akkomodatsii.

The article reviews the findings on the anatomy, morphological and biomechanical features of the accommodation apparatus. Modern methods of imaging and biometry confirm the validity of the Helmholtz lenticular theory of accommodation, according to which its mechanism involves three main components: the ciliary body, the zonular fibres and the lens capsule, the lens itself. Based on this, there is certain interest in studying the degree of participation of each of these components in the development of age-related changes in accommodation (presbyopia).

[Experimental studies of the biomechanical properties of the cornea]. / Eksperimental'nye issledovaniya biomekhanicheskikh svoistv rogovitsy.

The review presents the results of experimental studies of the biomechanical properties of the cornea. Selective evaluation of the individual corneal structures (for example, limiting membranes) using classical mechanical tests is to a certain extent limited due to the rather small thickness of these structures and the related difficulties in sample fixation. In real practice, the use of a method better adapted for conducting such studies - atomic force microscopy (AFM) - remains promising, since on the one hand it eliminates the need for mechanical capture and retention of the sample, and on the other - provides the capability for studying its segments separately.