[Strength properties of rabbit cornea after femtosecond laser keratoplasty with and without different intracorneal implants]. / Prochnostnye kharakteristiki rogovitsy krolika pri femtolazernoi keratoplastike s ispol'zovaniem razlichnykh intrarogovichnykh implantatov.

AIM: to conduct a comparative experimental study of the effect of the use of intracorneal implants during femtosecond laser-assisted intrastromal pocket (IP) and intrastromal tunnel (IT) formation on the strength properties of the cornea. MATERIAL AND METHODS: The experimental study was performed on 24 corneas of 12 rabbit eyes enucleated 1 month after slaughtering. All eyes were divided into 6 groups according to the method of operation. IP and IT were created with IntraLase FS 60 kHz femtolaser. Group 1 (control group) consisted of rabbit eyes with intact corneas. In group 2 corneas, intrastromal tunnels were formed, in group 3 - intrastromal pockets, and in group 4 - intrastromal tunnels with 2 intracorneal segments (ICS). In groups 5 and 6, intrastromal pockets, each supplemented with an intrastromal ring, were created at the depth of 62-72% and 80% of pachymetry readings from the 5.0-mm optical zone, respectively. RESULTS: Higher voltage had to be applied to stretch the samples from group 2 as compared to those from groups 3 and 6. Distribution of the Young's modulus of the test corneas agreed with voltage distribution in the study groups. CONCLUSION: IP was associated with greater reduction in corneal biomechanical stability as compared with IT. Ring implantation into an IP yielded a more pronounced increase in the strength properties of the cornea than ICS implantation into an IT. The result was also more favorable at greater depths of intrastromal ring implantation.

[Comparative analysis of corneal aberrations after intrastromal segments and MyoRing implantation using femtosecond laser in patients with keratoconus]. / Sravnitel'nyi analiz rogovichnykh aberratsii posle femtolazernoi implantatsii intrastromal'nykh segmentov i kolets pri keratokonuse.

AIM: to comparatively analyze corneal aberrations after intrastromal corneal segments (ICS) and MyoRing implantation using femtosecond laser in patients with stage II-III keratoconus (KC) by Pentacam examination. MATERIAL AND METHODS: We have operated on 135 patients (145 eyes) with stage II or III KC. Depending on surgical technique, all patients were divided into two groups. Group I consisted of patients with KC, who received optimized femtosecond laser-assisted MyoRing implantation, group II - of those, who received femtosecond laser-assisted ICS implantation. Depending on the stage of the disease, each group was further divided into two subgroups, for stage II and stage III KC, respectively. Before and after surgery, all patients underwent visometry, biomicroscopy, corneal topography, and corneal aberrations measurement under photopic and mesopic conditions on Pentacam. The follow-up period averaged 30 months (from 6 to 34 months). RESULTS: In both groups corneal aberrations significantly decreased after surgery, which was confirmed by an improvement in parameters of refraction and keratometry readings. CONCLUSION: Implantation of intrastromal MyoRings leads to a greater reduction in the total corneal aberration, higher-order aberrations under photopic and mesopic conditions, and spherical aberration under photopic conditions as compared to ICS in patients with stage III KC; a comparable reduction in the total corneal, higher-order, and spherical aberrations under photopic conditions as compared to ICS in patients with stage II KC; a comparable increase in spherical aberration under mesopic conditions as compared to ICS in patients with stage III KC.

[Comparative analysis of the value of information provided by anterior segment optical coherence tomography and confocal laser scanning microscopy for identifying the palisades of Vogt in normal limbus]. / Sravnitel'nyi analiz informativnosti issledovaniya palisad fogta metodami opticheskoi kogerentnoi tomografii i lazernoi skaniruyushchei konfokal'noi mikroskopii v norme.

AIM: to conduct a comparative analysis of the value of information provided by anterior segment optical coherence tomography (AS-OCT) and in vivo confocal laser scanning microscopy (CLSM) for identifying the palisades of Vogt (POV) in normal limbus. MATERIAL AND METHODS: POV were studied in 15 healthy participants (30 eyes) without any anterior segment disease. Two examination methods were used: AS-OCT En Face imaging (RTVue XR Avanti, 3D Cornea protocol) and CLSM (HRT3). Concordance of the results was then analyzed. RESULTS: Structural features of POV were distinguishable by both methods. CLSM was able to visualize POV in both the superior and inferior limbi of all the 15 patients (30 eyes). Within the inferior corneal hemisphere, POV had the appearance of well-differentiated hyperreflective double-contoured structures organized in parallel lines at the level of basal epithelium. The structure of the superior limbus, as judged from CLSM data, varied significantly: «classic¼ palisades were seen in only 13 eyes (43%), while in the other 17 cases (57%) POV were atypical. On OCT, POV structure was seen in detail in 29 eyes. By comparing the abilities of CLSM and OCT to visualize POV, a strong positive correlation (rS=0.99, p<0.05) was revealed between the results obtained in both the superior and inferior limbi. CONCLUSION: OCT data provide a detailed understanding of POV structure and strongly correlate with CLSM results. Taking into consideration the noninvasiveness, demonstrativeness, and repeatability of AS-OCT En Face imaging as well as the high value of provided information, the method cay be recommended as an alternative in POV diagnostics.

[Diagnostic capabilities of optical coherence tomography and confocal laser scanning microscopy in studying manifestations of aniridia-associated keratopathy]. / Diagnosticheskie vozmozhnosti opticheskoi kogerentnoi tomografii i lazernoi skaniruiushchei konfokal'noi mikroskopii v izuchenii proiavlenii aniridiinoi keratopatii.

AIM: to investigate the possible use of anterior segment optical coherence tomography (AS-OCT) and laser scanning confocal microscopy (LSCM) for visualization of limbal progenitor structures and epithelial changes at different stages of aniridia-associated keratopathy (AAK) and to analyze genotype-phenotype correlations of corneal damage. MATERIAL AND METHODS: Thirty-four patients (63 eyes) with congenital aniridia (CA) were subjected to epithelial cell density measurement in the central cornea as well as epithelial surface assessment with limbal palisades of Vogt (POV) detection in the corresponding sites of the two corneas. For that, LSCM (HRT3) and AS-OCT (RTVue XR Avanti) were performed. Central corneal and epithelial thicknesses were measured using the Pachymetry protocol. RESULTS: There has been found an increase in the central corneal thickness (CCT) of CA patients, which correlated with the stage of AAK, and a decrease in the central epithelial thickness as compared with healthy subjects (p<0.05). The difference between the basal and wing epithelial cells density in eyes with stages I and II AAK and normal cells density at stage 0 AAK was statistically significant (p<0.05). Intact or disturbed POV were detected in all patients with PAX6 3' deletion. At that, AS-OCT findings highly agreed with LSCM images for both the inferii (rS=0.85, p<0.05) and superior limbi (rS=0.53, p<0.05). A negative correlation was established between the stage of AAK and in vivo morphology of POV (rS=-0.5, p<0.05). However, no correlation was found between the stage of AAK and patient's age (rS=0.169, p=0.174). CONCLUSION: AS-OCT and LSCM are both important diagnostic tools for corneal surface monitoring in patients with limbal stem cells deficiency.

[Comparative evaluation of different corneal cross-linking techniques with respect to biomechanical stability of the cornea].

AIM: To perform a comparative analysis of the following cross-linking techniques: standard cross-linking (SCXL), local transepithelial femto cross-linking (LTF) and transepithelial intrastromal femto cross-linking with MyoRing implantation (TIF+MyoRing) in experimental animals and patients with progressive stage II--III keratoconus (KC), paying particular attention to the changes in biomechanical stability of the cornea. MATERIAL AND METHODS: The experimental series was performed on 20 eyes of 10 rabbits. The animals were divided into 4 groups of 5. Group 1 served as the control, group 2 consisted of animals that underwent SCXL, group 3 -- of those after LTF, and group 4 -- of those after TIF+MyoRing. Femto step was performed using the IntraLase FS 60 kHz femtosecond laser, cross-linking - with the Evolution machine. The follow-up period was 1 month. Clinical study enrolled 48 patients (45 eyes) with stage II-III KC. Depending on the surgical technique all the patients were divided into 3 groups. In group I (14 eyes, 9 patients), TIF+MyoRing was performed, in group II (16 eyes, 20 patients) --SCXL, in group III (15 eyes, 19 patients) -- LTF. The follow-up period was 6 months. RESULTS: The experiment showed a significant increase in rupture resistance of the cornea in all three groups. Six months after surgery, patients from group I demonstrated a 1.0±0.22 mmHg higher corneal resistance factor (CRF) and a 1.0±0.12 mmHg higher corneal hysteresis (CH). In group II, the said parameters increased by 0.8±0.10 mmHg and 0.6±0.16 mmHg, respectively; in group III -- by 0.8±0.25 mmHg and 0.6±0.26 mmHg, respectively. In neither group the density of endothelial cells has reduced significantly over the follow-up period. C-ONCLUSION: All three methods (LTF, TIF and SCXL) equally increase the biomechanical strength of the cornea and are safe. In patients with progressive stage II-III KC, TIF+MyoRing surgery has yielded an even higher improvement of biomechanical parameters in a 6-month follow-up period, which is due to the combination of mechanical and chemical mechanisms of corneal reinforcement.

[Corneal collagen cross-linking for keratoconus].

Over the last decade, corneal collagen cross-linking (CXL) has become a conventional treatment method for progressive keratoconus. Laboratory studies have shown that CXL increases the diameter of collagen fibers and also the number of intra- and interfibrillar cross-links, thus, increasing biomechanical strength of the irradiated cornea. As confirmed by a series of clinical and randomized controlled trials, CXL is able to slow down and, perhaps, to stop the progression of keratoconus. In most post-CXL patients visual acuity improves, while keratometric readings, spherical equivalent, and higher order aberrations reduce. Although published results prove CXL effective in the treatment of progressive keratoconus, its late consequences are yet unknown. This article reviews the stages of CXL development and results of published experimental and clinical studies. Prospects for CXL modifications that do not require epithelial debridement are discussed.

[Corneal intrastromal Myoring implantation in keratoconus].

The review discusses literature data on the treatment of keratoconus with intrastromal Myoring implantation into a corneal pocket, formed with a Pocket Maker microkeratome and a femtosecond laser alone and in combination with cross-linking of corneal collagen. The method shows high effectiveness as to refractive and functional outcomes and stabilization of keratoconus over the whole follow-up period (more than 3 years).

Regenerative activity of 2-(1'-hydroxy-4'-isopropenyl-1'-methylcyclohexyl-2'-thio) methyl ethanoate gel.

We studied regenerative activity of a sulfur-containing menthane terpenoid (2-(1'-hydroxy-4'-isopropenyl-1'-methylcyclohexyl-2'-thio) methyl ethanoate) in the form of gels with different concentrations in experimental superficial non-penetrating corneal wound. The examined compound significantly increased the regenerative activity by accelerating the onset and completion of epithelialization. The use of 2% and 3% gel ensured finer scarring.

[A novel model of artificial iris-lens diaphragm for reconstruction of extensive iris defects (experimental rationale)].

Experimental rationale is presented for novel model of artificial iris-lens diaphragm (ILD) that provides a better adaptation of diaphragm to anterior segment structures variable in size and reduction of pressure on ciliary body due to modifications in design of supporting elements. Presented model is good in self-centration, allows sutureless fixation in lens capsule or the other supporting structures in aniridia.

[New model of artificial iris-lens diaphragm for correction of large iris defects (clinical and functional results of implantation)].

The article presents clinical and functional results of model C iris-lens diaphragm (ILD) implantation to patients with aniridia or large iris defects. Modification of the supporting elements and new grooves at their base provide better adaptation of the diaphragm to individual eye sizes and reduces the impact exert upon reactive ocular structures. The new model shows good self centration and enables sutureless implantation in patients with aniridia if lens capsule or other supporting structures of the anterior chamber are present. Owing to design changes and lesser thickness of the new diaphragm, injection implantation onto the lens capsule is now possible.

[Efficacy of valve drainage devices in secondary glaucoma in patients with artificial iridolenticular diaphragm].

Results of 5 Akhmed valve implantations in patients with secondary glaucoma various time after artificial iridolenticular diaphragm implantation after concomitant iris and lens trauma were analyzed. Surgery allowed to achieve reliable IOP decrease when severe scar deformation of drainage zone of the anterior chamber prevents traditional hipotensive procedures because of their ineffectiveness. Besides visual acuity stabilization a safe performance of subsequent reconstructive procedures can become possible as well.

[Initial experience of threefocal diffractive/refractive intraocular lenses implantation].

Due to original Russian technique of frontal photopolimerization of liquid oligomers in form the use of threefocal intraocular lense (IOL) with square relief of diffractive surface has become possible. The first 36 implantations of MIOL-Record showed good clinical and functional results. This lens provides high quality of intermediate vision without decrease of distant and near visual acuity. 94% of patients completely refused spectacle correction for all distances. The vast majority of patients are satisfied with their intermediate vision, 94% of them don't use spectacles for computer work. Incidence of disphotopsias is similar to that after other MIOLs implantation.

[X-ray diagnostics of instability of vertebral-motor segment in lumbar-sacral part of the spine].

Degenerative diseases of the spine are one of the main social problems having important economical aspect since this pathology is mostly peculiar to people of young and middle age making the major part of able-bodied citizens. Diagnostics of lumbar vertebras displacement is one of the less studied problems of radiology. Instability - displacement of vertebras as one of the forms of dysfunction of motor segment becomes a cause of pain syndrome and following neurological disturbances.

[Experimental rationale for the use of a new model of the artificial iridolens stop for reconstructive surgery].

A new-design artificial iridolens stop (ILS) has been constructed, which is monolithic, elastic, universal by possible implantation modalities in relation to the degree of a damage to the anatomy of the anterior segment of the eye, adapted to surgery of minor incisions, and alleviating intra- and postoperative complications. The color spectrum of the haptic part of an ILS yields a good cosmetic effect. The ILS is made from a hydrophobic spatially sutured polymer based on polyoxypropylene. The experimental findings suggest that the proposed ILSs show a chemical and biomedical safety. The stops exert no locally irritant, sensitizing, and toxic effects, they are sterile, apyrogenic and meet the specifications of the items permanently contacting the internal environment of the eye.