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This review is devoted to the English- and Russian-language terminology of quantitative metrics that are used in the evaluation of images obtained by optical coherence tomography angiography (OCT-A). The paper presents an analysis of the use of terms characterizing intraretinal blood flow (vascular density, perfusion density, skeletonized density, etc.), area and shape of the foveal avascular zone, and choriocapillaris blood flow. The factors causing the heterogeneity of OCT-A terminology are described, including the lack of a unified international nomenclature for OCT-A, features of their Russian translation, inconsistency of the parameters in optical coherence tomography systems of different manufacturers. The article also considers ways to standardize the terminology.

This article, composed using literary sources and archival materials, is dedicated to the 155th anniversary of Alexander Grigoryevich Lyutkevich - a prominent Russian ophthalmologist of the late 19th and early 20th centuries (12.09.1867-18.04.1928) and one of the founders of the Voronezh Medical Institute. The paper traces the main stages of his biography, notes his work in rapid-reaction emergency care units, and pays attention to his teaching activities. The importance of Lyutkevich's doctoral dissertation on the treatment of high myopia is emphasized. The article also highlights his important role as editor of the classic textbook "Course of eye diseases" by A.A. Kryukov. In Lyutkevich's public activities, his contribution to the establishment of the Society of Ophthalmologists in Moscow is particularly noteworthy. Lyutkevich's high organizational skills are highlighted, which were clearly manifested in the Yuriev University and in the creation of the medical faculty of the Voronezh University.

Application of new materials and methods in the diagnosis and treatment of eye diseases is one of the promising research areas in modern ophthalmology. Significant progress has been made in understanding the pathogenesis, diagnosis and treatment of eye diseases using nanotechnologies and nanomaterials. This paper presents the main achievements and results of original research on this issue. It has been shown that nanoparticles are able to overcome biological barriers, deliver drugs to the target site, and provide the required drug release rate. Modern nanotechnological approaches in tissue engineering are also being actively introduced into ophthalmology, making it possible to create nanoframeworks for growing three-dimensional cellular structures, including arrays of pigment epithelium cells and retinal ganglion cells for the treatment of retinal damage caused by degenerative diseases, injuries and infections.

This paper reviews the literature on the role of optical coherence tomography (OCT) and optical coherence tomography angiography (OCTA) in the diagnosis of glaucoma and considers the significance of evaluating retinal nerve fiber layer and ganglion cell complex in assessment of glaucoma progression, variability and reproducibility of the method, as well as the influence of age-related retinal changes on the results, analyzes the role of OCTA in glaucoma monitoring. Optical coherence tomography is a modern standard for glaucoma diagnosis and monitoring, and OCTA shows high potential as an auxiliary diagnostic tool.

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.

In recent years, a new class of extended depth of focus (EDOF) intraocular lenses (IOLs) has become available on the market. There is only a limited number of scientific papers comparing trifocal and EDOF IOL data, and the results are often contradictory., Purpose: Comparative analysis of the results of trifocal and EDOF IOL implantation in patients with presbyopia and/or cataract., Material and Methods: This prospective study included 72 patients (144 eyes) after bilateral implantation of either Tecnis Symfony EDOF IOL (18 patients, 36 eyes; group I) or AcrySof PanOptix trifocal IOL (54 patients, 108 eyes; group II). In 18 patients out of 72 (25%) the implantation involved mini-monovision, i.e. the calculation of the IOL power on the nondominant eye was performed at -0.5 D. The average follow-up period for the patients was 7.1±1.2 months., Results: There was a significant ( p <0.05) increase in uncorrected near visual acuity (UCNVA), uncorrected intermediate visual acuity (UCIVA) and uncorrected distance visual acuity (UCDVA) at the maximum follow-up time compared to the preoperative indices in all groups. Group II was characterized by slightly better UCNVA dynamics (0.85±0.13 versus 0.2±0.04 before surgery, as comparted to 0.78±0.11 versus 0.19±0.06 before surgery in group I), but differences were not statistically significant ( p >0.05). Statistically significant differences ( p =0.046) were observed when comparing best corrected near vision acuity (BCNVA) in groups I and II (0.79±0.05 and 0.98±0.08, respectively) at 6 months compared to the preoperative period (0.62±0.09 and 0.6±0.11, respectively)., Conclusion: Trifocal IOL implantation was associated with acceptable near and far vision correction and a higher frequency of adverse optical phenomena, while implantation of the EDOF IOL was associated with slightly better correction of intermediate vision and a significantly lower incidence of halo and glare. Patients were satisfied with the outcomes of surgery in all cases.

Objective: To review the literature devoted to the problem of primary anterior chamber angle closure (PAC) and the development of this pathology from glaucoma suspect to primary angle closure glaucoma. The paper includes a trend analysis of the studies concerning primary angle closure suspects (PACS). The concept of this review is conditioned by the conflicting strategies for treating patients with initial PAC without glaucomatous optic neuropathy. Solving the problem of angle closure plays a key role in preventing the development of PAC glaucoma, which is the world's leading cause of irreversible blindness. This part of the review provides information on the frequency and rate of disease progression in PACS. The analyzed literature data is contradictory and indicates the need for further search that would consider a standardized approach to defining the concept of PAC disease, demographic factors and unified examination methods for generalizing and systematizing data in order to draw out unified treatment recommendations.

The World Health Organization recommends monitoring the trends and assessing the progress of ophthalmic care focused on the actual needs of people. To solve these problems, the authors of this paper have proposed and tested an analytical model, named «Cataract», which on the one hand can help evaluate the needs of the population in terms of cataract treatment, and on the other - assist with analysis of the available resources to meet these needs. The model can help identify the bottlenecks and predict the required resources, as well as assess the degree of satisfaction of the population's needs with the current and projected amount of medical care. This model allows analyzing, planning or predicting the resources of healthcare facilities needed for the treatment of cataracts while simultaneously assessing its impact in order to meet the medical needs of patients with cataracts.

Posterior chamber phakic intraocular lens (PIOL) implantation is a widely accepted and performed refractive surgery for correction of moderate and high myopia used when corneal laser ablation procedures are not suitable. This paper analyzes literature data to reveal the advantages and limitations of the technology.

The most well-studied and widely prescribed fixed-combination drug for open-angle glaucoma is latanoprost/timolol. Its significant hypotensive effect is especially important in challenging cases, among which are patients with normal-tension glaucoma. With long life expectancy and the constant need for treatment, requirements are high for both the effectiveness of the drug and its tolerability. This paper presents a follow-up of 7 patients with normal-tension glaucoma who have been using the fixed combination of latanoprost/timolol for 10 years. All patients showed very good tolerability to the drug and their quality of life was preserved. A moderate rate of disease progression according to static perimetry was noted in one case. A mild degree of dry eye syndrome according to the OSDI questionnaire and an objective assessment of the state of the ocular surface was observed in one patient. The latanoprost/timolol fixed combination is a well-tolerated, highly effective and safe long-term treatment choice for normal-tension glaucoma.

Purpose: To determine the possibilities of impression cytology (IC) with subsequent visualization of the sample on a scanning electron microscope in assessment of normal microflora of the ocular surface., Materials and Methods: The article presents a visual characteristic of the microorganisms of the ocular surface (OS) captured during impression cytology (IC) in individuals without signs of inflammatory and degenerative eye diseases. The original method of staining the sample with heavy metal salts made it possible to identify the individual signs of the microorganisms in their subsequent visualization by scanning electron microscopy (SEM)., Results: The paper presents photomicrographs of the microorganisms most common for the OS obtained with the help of SEM, confirming and supplementing the data of non-visual methods of studying the ocular microflora. It was shown that the detection frequency of the microbial component of the OS by the visual method presented in this study is comparable with the detection frequency when using the microbial cultivation method (<80%). Coccoid and rod-shaped microorganisms were detected with relatively equal frequency, with the coccoid organisms mainly represented in association with epithelial cells. The morphological diversity of rod-shaped microorganisms is shown., Conclusion: The results of the study can be used as a visual reference for the normal microbiome of the eye.

The article reviews international and Russian scientific papers concerning the possibility of transmitting coronavirus infections, particularly the COVID-19, through eye surface. According to the studied literature, the incidence of ocular symptoms in COVID-19 is around 0.8-31.6%, with conjunctivitis being the most frequent manifestation. The review summarizes data on virus detection in conjunctival discharge of COVID-19 patients. Across six studies, the total number of patients is 252, among which were 8 cases (3.17%) of virus detection in the conjunctival cavity. The review discusses the reasons for infrequent detection of the virus in the lacrimal fluid. The analyzed data shows that COVID-19 associated conjunctivitis can be the first symptom, the primary manifestation, or sometimes be detected in the lacrimal fluid of patients without any concomitant signs of eye surface inflammation. The article also presents two clinical cases of patients with keratoconjunctivitis and conjunctivitis associated with COVID-19, as well as the results of experimental transconjunctival and respiratory exposure of Rhesus macaques to SARS-CoV-2 with conclusion of possibility of this type of transmission. Additionally, the review contains the opinion of researchers concerning the influence of several factors on the possibility of virus detection in the lacrimal fluid. The conclusion was made that there is possibility of COVID-19 transmission through the eye surface. While it is not being considered a major transmission route, it should not be ignored. Conjunctival cavity of COVID-19 patients can be the source of infection. Eye protection measures should be undertaken when working with potentially infected patients.

This paper describes possible clinical ocular manifestations of novel coronavirus infection COVID-19. Two clinical cases of conjunctivitis are examined. Due to the lack of ophthalmological approaches to the treatment of such patients, different management tactics are given based on the severity of local and systemic disease manifestations. Our research and practical management of these conditions showed the toxic and allergic nature of ocular surface manifestations in patients with COVID-19. Such cases are proposed to be treated similar to the conjunctivitis of "unclear origin" with components from antiviral and anti-allergic therapies.

The review addresses the current state of atomic force microscopy (AFM) usage in ophthalmology. Briefly presented here are the history of the development of AFM, principles and modes of operation, its advantages, disadvantages, as well as a comparison with other types of microscopy. The review describes the capabilities of AFM in visualization of various structures of the eye. A significant part of the review is devoted to the study of the retina, which arouses great interest among researchers. In particular, the possibilities of AFM for visualization at the submicron level of various structures in the retina, such as the internal limiting membrane, membrane cells, Müller cells, retinal pigment epithelium in their normal state and in the presence of a pathology (age-related macular degeneration, diabetes mellitus) were reviewed. In addition, several study papers were analyzed, providing a base for the judgement of the mechanical properties of said structures. An AFM study of the visual pigment rhodopsin helped identify its dimeric structure. The stability of the rhodopsin molecule was proved to be determined by the degree of strength of its individual segments connected to each other. The AFM method is a highly accurate method that helps solve many fundamental and practical problems, particularly in ophthalmology.

Purpose: To develop methods for evaluating effectiveness of YAG-laser vitreolysis of vitreous floaters., Material and Methods: The study included 144 patients (173 eyes) who had underwent YAG-laser vitreolysis and were under observation from 01.09.16 to 31.01.18. The patients were 34 to 86 years old (mean age 62.7±10.2 years), 28 (19.4%) patients were male, 116 (80.6%) - female. All patients underwent standard and additional examination: ultrasonography (Accutome B-scan plus, U.S.A.), optic biometry (Lenstar 900, Haag-Streit, Switzerland), spectral optical coherence tomography using RTVue XR Avanti scanner (Optovue, U.S.A.) in modes Enhanced HD Line, 3D Retina, 3D Widefield MCT, Cross Line, Angio Retina, and scanning laser ophthalmoscopy (SLO) using Navilas 577s system. Laser vitreolysis was performed using the Ultra Q Reflex laser (Ellex, Australia)., Results: This paper presents methods of objective quantitative and qualitative assessment of artifactual shadows of vitreous floaters with spectral optical coherence tomographic scanner RTVue xR Avanti employing an algorithm of automatic detection of non-perfusion zones in modes Angio Retina, HD Angio Retina, as well as foveal avascular zone (FAZ) measurement with Angio Analytics® software. SLO performed with Navilas 577s was used as method of visualizing floaters and artifactual shadows in retinal surface layers prior to surgical treatment and after YAG-laser vitreolysis., Conclusion: Suggested methods of quantitative and qualitative assessment of artifactual shadows of the floaters in retinal layers are promising and may prove to be highly relevant for clinical monitoring of patients, optimization of treatment indications and evaluating effectiveness of YAG-laser vitreolysis. Further research of laser vitreolysis effectiveness in patients with vitreous floaters is necessary.

The paper describes the role of endogenous glucocorticoids in the pathogenesis of open-angle glaucoma. As to steroid-induced glaucoma (SG), however, indicators of systemic and local cortisol metabolism are yet underinvestigated. Aim - to determine and compare systemic (plasma) and local (aqueous humour) cortisol concentrations in patients with SG and other types of glaucoma (OTG)., Material and Methods: A prospective analysis was conducted in 64 patients who underwent plasma and aqueous humor sampling. All the patients were divided into 4 groups: group 1 - 11 patients with steroid induced ocular hypertension (SOH) and SG; group 2 - 31 patients with OTG; group 3 - 10 patients on steroid therapy (ST) without a so called 'steroid response'; group 4 - the controls (12 patients with cataract)., Results: The mean cortisol levels in plasma and aqueous humour were the following: 177.5±29.4 ng/ml and 53.1±12.2 ng/ml in patients with SOH and SG; 277.7±33.6 ng/ml and 44.6±4.4 ng/ml in patients with OTG; 125.2±28.1 ng/ml in patients on ST; 147.2±19.1 ng/ml and 29.8±3.2 ng/ml in the controls. The highest plasma and aqueous humour cortisol levels were found in groups 2 and 1, respectively., Conclusion: Plasma and aqueous humour levels of cortisol appeared to be higher in glaucoma patients than in the controls. Taking into account the fact that plasma cortisol levels are higher in steroid responders, it is recommended that all patients on ST undergo cortisol testing.

This paper reviews studies on biomechanical properties of the anterior lens capsule. Early experiments in this field were more fundamental. Later studies were aimed mainly at assessing the mechanical stability of the capsule edge after manual or femtosecond laser capsulorhexis (capsulotomy) - an important step in modern minimally invasive phaco surgery. For biomechanical tests, ex vivo samples of human and animal anterior capsules were used. The results of the studies presented here are quite heterogeneous, which suggests the necessity of gaining further insight into the issue.

In this paper, technical details of visual evoked potentials (VEP) assessment and pattern electroretinography (PERG) are reviewed. Both methods are used to perform an objective functional examination of visual channels and to clarify the level, at which they have been damaged. Contributions of parvo- (P), magno- (M) and koniocellular (K) systems to the morphology of PERG and VEP responses are discussed with account to test conditions, selectively supportive of the activity of particular cell populations. The review analyzes the physiological role of such stimulation parameters as brightness and color contrast of the pattern elements as well as spatial and temporal frequency in detecting dysfunction of color channels and mistuning of the P- and M- pathways. Different times taken for neuronal integration and signal conduction along the M- and P- pathways determine the timing of the P- and M- VEP components, allowing us to judge their contribution to VEP morphology from the same recording.

The paper presents an atypical case of solar retinopathy after short-term exposure to reflected focused sunbeams. An ophthalmoscopic peculiarity was the presence of intraretinal hemorrhage. The basis for establishing the diagnosis were spectral optical coherence tomography and fluorescein angiography findings.

Aim: To analyze anatomical and topographic optic disc parameters with account to the disc area in glaucoma suspects., Material and Methods: The study included 302 patients (408 eyes) aged 25 to 76 years (the mean age of 50.5±12.5 years); men and women roughly equal in number. The eyes were divided into 8 groups depending on the disc area, which ranged from 0.89 to 3.5 mm2. With HRT, 11 global and sector optic disc parameters were examined, 4 of which (disc area, rim area, cup/disc ratio, mean RNFL thickness) are presented in this paper., Results: The study revealed a great variability of disc area values as well as individual morphometric features of the examined optic discs. We have also established high statistical significance of the difference between the above-listed optic disc parameters, both global and sectoral, in groups with different disc areas with the exception of the mean RNFL thickness., Conclusion: For early glaucoma detection with HRT, it is advisable to consider the individual area-dependent anatomical and topographic features of the optic disc.

The paper presents an original method for temporary biokeratoprothetics in total destruction of the cornea, which consists of the following. In the operating room a 12-mm disc is cut out of patient's conchal cartilage by a trephine and then thinned down to 1 mm with a blade. The prepared autograft is placed in front of the iris completely overlapping corneal defect and sutured to the sclera with 10--12 U-shaped interrupted stitches using a 7/0 suture. Between the stitches 0.2--0.3 ml of viscoelastic are injected into the anterior chamber. Temporary blepharorrhaphy is done within the temporal one-third of the eyelids with a U-shaped suture 6/0. The authors present an own clinical observation of patient D., aged 46, with purulent corneal ulcer and total destruction of the cornea. In ophthalmic emergency, if no donor cornea is available, the described method allows to save the eyeball from its anatomical and functional loss. Further routine keratoplasty or optical keratoprosthetics may bring some functional improvement.

The paper presents clinical and morphological case analysis of primary intraocular malignant medulloepitelioma (medulloblastoma) of rare localization (central part of the retina with optic nerve involvement) that simulated retinoblastoma in a 2-year-old child. Histological features of the tumor are given in details (tubular and mesh structures of the tumor, rosettes, ribbons, cells with hyperchromic nuclei, and cellular polymorphism). An experience of creating a primary intraocular malignant medulloepitelioma cell culture, as yet exclusive in the Russian Federation, is described. Culture sensitivity for particular drugs (oxaliplatin, irinotecan, ifosfamide, and ascorbic acid at different concentrations) was evaluated by MTT-assay. Of the four products, IC50 (3.3 mg/ml) was obtained only for ascorbic acid. Despite the relative rarity of primary intraocular malignant medulloepitelioma, its differential diagnosis should be carried out, with retinoblastoma in mind in the first place. The obtained data on the effectiveness of ascorbic acid against intraocular malignant medulloepitelioma cells can be used to supplement the existing chemotherapeutic protocols in pediatric ocular and neuro-oncology.

Advanced purulent corneal ulcer, as well as abscess, is a serious vision-threatening condition notable for its fulminant course and possible loss of the eye due to endophthalmitis. Its leading causes, pathogenesis, and classifications are described and analyzed in this paper.

The paper presents an integrated analysis of clinical, instrumental, and morphological data on a very rare pathological condition-- simultaneous ocular and orbital involvement in a lymphoproliferative disorder.

Uveal melanoma is a malignant intraocular tumor associated with poor vital prognosis, process generalization, and death from metastatic disease. A number of factors are considered undesirable in the presence of a tumor. This paper provides a review of the literature on major prognostic factors for uveal melanoma development and their contribution to vital prognosis.