[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.

[Physical therapy - the main focus of modern ophthalmic rehabilitation]. / Fizioterapiya ­ osnovnoe napravlenie sovremennoi oftal'moreabilitatsii.

Ophthalmic rehabilitation consists of improving or maintaining the functions of the visual analyzer within the possibilities of the "therapeutic window". Ophthalmic rehabilitation involves physiotherapeutic methods, as well as additional ones that improve the condition of the body and indirectly affect the organ of vision. This article presents schematic algorithms of physiotherapeutic ophthalmic stimulation in neurodystrophic diseases of the visual organ and the main results of their multifactorial objective and subjective analysis. It was shown that even with the consistent visual resolution, treatment courses can help get positive changes at the level of nerve structures lasting for three to six months. This allows us to recommend physiotherapeutic ophthalmic stimulation for maintaining the therapeutic effects obtained after the main medical or surgical treatment.

[Cell cultures - model object for experimental studies in ophthalmology]. / Kletochnye kul'tury ­ model'nyi ob"ekt dlya eksperimental'nykh issledovanii v oftal'mologii.

The article presents results obtained on several types of model cultures. Primary cultures of corneal epithelial cells and fibroblast-like cells from the limbus were obtained from the tissues of the anterior eye segment. Tests were performed on these cultures to determine the cytotoxicity of antiglaucoma drugs and to trial a protection method. In addition, a comparative analysis of the regenerative potential of various blood derivatives was carried out. An in vitro culture of endotheliocytes showed a correlation between the degree of damaging effects of antiglaucoma drugs of various groups and the content of the preservative benzalkonium chloride in their composition. Corneal keratocytes were used to create a cell sheet reflecting the main structural features of the stroma and suitable for biomechanical tests. The antifibrotic activity of the drugs was tested on the culture of fibroblasts from the nasolacrimal duct. The conducted studies demonstrate that cell cultures can be used as an informative model object for researching the pathogenesis of ophthalmic diseases and for testing drugs.

[Features of water-electrolyte component of the tear fluid]. / Osobennosti vodno-elektrolitnogo komponenta sleznoi zhidkosti.

Tear production is a complex multi-step process that can be arbitrarily divided into three stages: «primary¼ secretion by the acinar cells of the main lacrimal glands, formation of «secondary¼ lacrimal fluid in the ducts of the main lacrimal glands, and «tertiary¼ 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.

[The effect of phacoemulsification of age-related cataract on intraocular pressure and iridocorneal angle parameters in primary open-angle glaucoma]. / Vliyanie fakoemul'sifikatsii vozrastnoi katarakty na uroven' oftal'motonusa i parametry iridokorneal'nogo ugla pri pervichnoi otkrytougol'noi glaukome.

Cataract phacoemulsification with intraocular lens implantation significantly affects the morphology of the anterior chamber angle (ACA) and contributes to a reduction of intraocular pressure (IOP). PURPOSE: This study investigates the changes in anterior chamber angle configuration and IOP level before and after cataract surgery in primary open-angle glaucoma (POAG) eyes, and assesses its possible relationship with the axial length of the eye. MATERIAL AND METHODS: The study included 38 patients with immature senile cataract and compensated unoperated stage I-II POAG. Patients underwent anterior segment optical coherence tomography (AS-OCT) with measurement of the angle opening distance (AOD750) and trabecular-iris space area (TISA750) before and six weeks after the surgery, as well as axial length and corneal-compensated IOP (IOPcc). RESULTS: After the surgery 92.11% of patients showed a decrease in IOPcc an average of 1.84±1.95 mm Hg (by 12.33±10.21% of the baseline); the maximum decrease in the IOPcc level was 8.35 mm Hg (by 40.97% of the baseline). AS-OCT data indicates that cataract phacoemulsification causes an increase in anterior chamber angle width: AOD750 increased from 0.510±0.175 to 0.771±0.156 mm, and TISA750 increased from 0.266±0.090 to 0.494±0.096 mm2. The strongest correlations were found between the axial length, postoperative TISA750 increase (Δ%TISA750) and postoperative IOPcc reduction (Δ% IOPcc). Postoperatively, specific changes could be observed in the trabecular meshwork in 28.95% of cases in the form of elongation and strain of the membrane. CONCLUSIONS: Cataract extraction contributes to a significant reduction in IOP due to anterior chamber angle expansion, trabecular meshwork stretching, and improved aqueous outflow.

[Mineral dysmetabolism in corneal diseases]. / Narusheniya mineral'nogo obmena pri zabolevaniyakh rogovitsy.

Functional status and biological properties of connective tissues significantly depend on the mineral elements involved in their metabolism. Connective tissue portion of the corneal stroma makes up most of its thickness; pathological changes in collagen fibers and the stroma can cause a range of corneal diseases, some of which are specifically associated with disorders of mineral metabolism. The article considers impairments of mineral metabolism as possible pathophysiological mechanisms in certain diseases and disorders of the cornea, and describes in detail the abnormalities associated with mineral dysmetabolism observed in patients with keratoconus.

[Ocular iontophoresis]. / Lekarstvennyi elektroforez v oftal'mologii.

Iontophoresis in medicine is a combined pharmacological and physical method of treatment that unites the therapeutic effect of an electric current with the pharmacological effect of medicinal substances administered at the same time via an electric current. The article describes the physical basis of the therapeutic effect of direct electric current on biological tissues, and highlights the physical and chemical mechanisms of target administration of pharmaceutical substances into the human body through intact skin or mucous membrane by means of direct electric current. In addition, it presents the results of international as well as Russian domestic scientific studies on the clinical effectiveness of iontophoresis in ophthalmology.

[Results of laser confocal microscopy of the cornea in viral uveitis (a preliminary report)]. / Rezul'taty lazernoi konfokal'noi mikroskopii rogovitsy pri virusnykh uveitakh (predvaritel'noe soobshchenie).

Herpesviruses involve neurotropic activity (they affect nerve cells) and have the ability to induce an immune response (a special tropism for immune tissue), which provides a valid reason for studying the possibilities of visualizing nerve fibers of the cornea and Langerhans cells (LC) in viral uveitis (with prospective applications in early diagnosis). PURPOSE: To evaluate the results of laser corneal confocal microscopy (CCM) in viral uveitis of varying localization. MATERIAL AND METHODS: The main study group included 23 patients (23 eyes) diagnosed with unilateral herpesviral uveitis (chorioretinitis), the patients' age varied from 18 to 79 years. The control group comprised 19 healthy volunteers (38 eyes) aged 20 to 75 years. In addition, the paired eyes of the main group patients were examined. In all patients, standard ophthalmologic examination was complemented with CCM performed on the HRT III device with a corneal module, followed by analysis of the course and structure of corneal nerve fibers (CNF) using copyrighted software Liner 1.2. CONCLUSION: The preliminary results achieved in this study outline the prospects for further research on the state of cornea (in particular, changes in the course and structure of CNF, and the presence of dendritiform cells of Langerhans) with laser CCM in patients with uveitis of various etiologies. These morphological changes also has potential use as diagnostic markers of inflammation of the uveal tract. The main criteria for assessing the state of cornea in viral uveitis include the following: increased tortuosity of CNF, increase in the number and size of Langerhans cells. Further research - in particular, studying the integrated use of diagnostic methods necessary for the verification of viral uveitis, as well as detailed analysis of the history and clinical picture of the disease - is required to substantiate the inclusion of laser confocal microscopy method in the algorithm for the diagnosis of viral uveitis.

[Reasons to reconsider interpretation of densitometry for corneal transparency]. / O neobkhodimosti peresmotra interpretatsii dannykh densitometricheskoi otsenki prozrachnosti rogovitsy.

AIM: To assess the effect of light scattering in the corneal epithelium on densitometric brightness of the stroma through mathematical modeling of the interaction between a light beam and the two-layer epithelium-stroma system. MATERIAL AND METHODS: In order to study the scattering behavior of a plane-parallel non-coherent beam at the epithelium-stroma interface, a multi-age group was formed (87 patients, 174 eyes) that comprised two subgroups with equal number of assign participants: healthy patients with no systemic changes and mixed patients with undisturbed corneal transparency that, nevertheless, were under instillation therapy. In the first subgroup, the assessment of light scattering was done at random times, while in the second subgroup - within the first 200 seconds after the instillation in order to avoid a reaction of the ocular surface structures, including epithelium (rapid response of epithelial cells to instillations). Light scattering intensity was measured with Pentacam (USA). The densitometric curve and brightness maxima of the epithelium and neighboring stroma as well as the mid and upper stroma were recorded for each patient. RESULTS: A physico-mathematical model of the interaction between a light beam and the two-layer epithelium-stroma system was created. The study confirmed our theoretical CONCLUSION: on the effect size of light scattering intensity on the apparent densitometric brightness of the stroma. CONCLUSION: Direct densitometry of multilayered spherical objects, of which each layer possesses its own optical properties, has been proved inaccurate. Complex optical interactions in a multilayered model cause a false increase in brightness of more transparent layers that lie behind those with pronounced light scattering properties. The function that describes the false increase in scattering ability of the layer that is more transparent rises sharply at the border between the layers.

[Ocular surface system integrity].

The interplay of different structures belonging to either the anterior segment of the eye or its accessory visual apparatus, which all share common embryological, anatomical, functional, and physiological features, is discussed. Explanation of such terms, as ocular surface, lacrimal functional unit, and ocular surface system, is provided.

[Abnormal distribution of trace elements in keratoconic corneas]. / Pereraspredelenie mineral'nykh elementov v rogovitse pri keratokonuse.

UNLABELLED: Our understanding of etiology and pathogenesis of many disorders, corneal included, greatly relies on existing knowledge in human biochemistry and biophysics. This study was aimed at chemical mapping of normal and keratoconic corneas. MATERIAL AND METHODS: Modern methods of analytical chemistry, such as X-ray fluorescence and energy-dispersive X-ray spectroscopy on the basis of scanning electron microscopy, were adapted to the needs of cornea research. Normal human corneas obtained postmortem and corneal buttons obtained during penetrating keratoplasty were analyzed. RESULTS: In keratoconus, abnormal accumulation of iron, copper, and zinc was found in the periphery of the buttons, i.e. in the zone of visible pigmentation (Fleischer ring), while the center - the ectatic zone - demonstrated a total deficiency of trace elements. This data suggests that keratoconus pathogenesis is associated with impaired mineral metabolism and formation of a physicochemical barrier in corneal tissues with subsequent keratectasia. The authors discuss several possible vicious circles involved.