[Ocular surface system integrity]

[The role of miRNA in the pathogenesis of diseases associated with functional dysregulation of the lacrimal gland]

At this time, the mechanism causing lacrimal gland dysfunction is not understood completely. In diseases associated with lacrimal gland involvement (Sjogren's syndrome, sarcoidosis, IgG4-associated disease, etc.) patients have been observed to experience elevated cellular apoptosis, active production of autoantibodies to glandular tissue, increased level of pro-inflammatory cytokines, functional disruption of signaling molecules leading to changes in tear production. Difficulties in differential diagnosis of lacrimal gland dysfunction in above-listed diseases are associated, on the one hand, with similarity of the clinical picture of ophthalmological manifestations, and on the other hand - with complicated morphological interpretation of changes in the glandular tissues. In this view, miRNA is a promising diagnostic and prognostic marker that would help with differential diagnosis as well as with choosing the treatment tactics. Methods of molecular profiling and identification of "molecular phenotypes" of lacrimal gland and ocular surface damage will allow the use of miRNA as biomarkers and prognostic factors for personalized treatment.

[Features of water-electrolyte component of the tear fluid]

Tear production is a complex multi-step process that can be arbitrarily divided into three stages: «primary» secretion by the acinar cells of the main lacrimal glands, formation of «secondary» lacrimal fluid in the ducts of the main lacrimal glands, and «tertiary» modification of the tear composition in the conjunctival sac. This article highlights mechanisms of water and electrolytes secretion in the process of tear fluid production and describes the particularities of distribution of the membrane transport proteins in the lacrimal gland and the ocular surface.

Terahertz radiation in ophthalmology (review)

Terahertz (THz) radiation is one of the new, intensively studied interdisciplinary fi elds of scientifi c knowledge, including medicine, in the fi rst decades of the 21st century. At the beginning of this article (review), in a brief form, the basic statements on THz radiation, the main parameters and properties are presented; the modern THz biophtonics technologies used in biology and medicine are considered – THz refl ectometry, THz spectroscopy methods. Then a number of directions and examples of possible use of THz technologies in biology and medicine, including pharmaceuticals, are given. The main part of the review presents the progress of experimental research and the prospects for the clinical application of medical technologies of THz spectroscopy, THz imaging, in ophthalmology in the study of the morphological and functional state of the ocular surface structures, diagnosis, medical testing, and treatment of ophthalmopathology of the ocular surface. The article concludes with a review of experimental studies on the safety of using THz waves for medical diagnostics and treatment of ophthalmopathology. In the fi nal part, the main problems and prospects of introducing medical THz technologies into the clinical practice of an ophthalmologist are considered.

[Current methods of tear film stability assessment]

Dry eye syndrome (DES) is a multifactorial disease of the ocular surface characterized by a loss of homeostasis of the tear film, and accompanied by ocular symptoms, in which tear film instability and hyperosmolarity, ocular surface inflammation and damage, and neurosensory abnormalities play etiological roles. The clinical manifestations of DES can be highly variable, so its diagnosing is typically based on a combination of symptoms, signs, and clinical tests. Majority of the techniques involved in the diagnosis of this disease has a large degree of subjectivity. The present article reviews current dry eye diagnostic tests and presents a new tear film stability assessment technique that may potentially become the objective method for establishing DES diagnosis.

[Prognostic value of changes in the cornea and conjunctiva in diabetes mellitus]

Diabetes mellitus (DM) is the most common endocrine disease, and therefore a pressing medical and social problem. In many cases, ocular manifestations of DM are considered the particular cause of patients' disability. The review presents an analysis of morphological, experimental and clinical studies of the cornea in patients with diabetes mellitus - full articles, reviews and monographs of Russian and foreign authors, mostly those published in the recent years. Among the considered topics are modern methods of examining conjunctiva and cornea, clinical and morphological changes in these tissues, and the early diabetic changes in all their structural layers. The review also describes the importance of diabetes-related changes in the conjunctival vessels and corneal nerve fibers and shows the correlation between the densities of corneal nerve fibers and epidermal nerve fibers.

Correlation Analysis of Ocular Symptoms and Signs in Patients with Dry Eye

Purpose. To analyze the correlations between the ocular surface signs and symptoms in patients with dry eye. Methods. In this observational study, 176 dry eye patients, including 60 males and 116 females, were enrolled and their dry eye symptoms and ocular signs were observed. Partial correlation analysis was conducted between OSDI score and each ocular surface sign, and the correlations were further discussed in different age groups. Then multiple linear regression analysis was used to further explore the influence of these signs on OSDI score. Results. Our correlation analyses showed that rounding of lid margins, notching of lid margins, vascularity of lid margins, hyperkeratinization, plugging of orifices, main duct dropout, and conjunctival congestion all had a positive correlation with OSDI score, while main duct number (central 1 cm) and BUT had a negative one. Further analysis suggested that these correlations varied in different age groups. Multiple linear regression analysis indicated that main duct number (central 1 cm), rounding of lid margins, and hyperkeratinization significantly affected OSDI score. Conclusions. Close attention should be paid to the morphology and structure of the eyelid margin and the function of meibomian gland in the diagnosis, treatment, and follow-up of dry eye diseases.

Cornea and its changes in diabetes mellitus: the review

Diabetes mellitus (DM) is the most common endocrine disease, which makes it a priority among health and social problems. Ocular manifestations in diabetes often lead to patient disability. This review presents an analysis of morphological, experimental and clinical studies of the cornea in patients with diabetes mellitus, including original research, reviews and monographs of Russian and foreign authors from recent years. In addition, modern methods of corneal disease diagnosis are reviewed. Clinical and morphological changes in the diabetic cornea are discussed and early diabetic changes in all structural layers are indicated. The importance of changes to nerve fibres in diabetes is discussed and the correlation between the density of nerve fibres in the cornea and the density of epidermal nerve fibres is shown.