№2, 2020, volume 16

The purpose is to study biomechanical parameters of elastin biomaterial's (BM) fibroarchitectonics. Material and Methods. For the study we usedxenogenic biomaterial made on the basis of the ligamentum nuchae (L. n.)) Bos taurus taurus, L. 1758. For histological examination of BM (n=24), we used electron microscopy (Jem-1011 microscope) and reflected light microscopy of histotopographic sections in the three planes, taking into account the orientation of elastic fibers (EF). Sections were stained with oreina, as well as according to Mallory and Van Gizon, they were impregnated according to Fut method. The mechanical properties of the material were studied on 11 samples with a size of 10x8x16 mm using a Zwick/Roell Z010 breaking machine, which allows for compression deformation. The strength of the suture fixation was determined by the tensile load (Pmax). To characterize the elastic properties of BM, the Young's modulus was calculated. Results. In the elastic deformation zone, the Young's modulus was 1.74±0.1 N/mm2. Subsequent loading of the BM led to deformations with stratification and formation of lamellar fragments. After removing the load, the BM restored its shape and size. BM fibroarchitectonics provides high strength of suture fixation. Conclusion. The BM fibroarchitectonics and the set of its structures form a single elastic-collagen complex. The results allowed us to develop structurally modified BM with osteoinductive properties.

The purpose of the investigation is to analyze prevalence and progression of retinopathy of prematurity depending on gestational age and solar activity at the time of birth. Material and Methods. 229 cases of premature babies born from 2017 to 2019 were randomly selected. They were divided into two groups: group I — children with retinopathy of prematurity (1, 2 and 3 degree) and group II —without any retinopathy (pre retinopathy). The disease outcome was taken into account in children with retinopathy of prematurity: children undergone laser coagulation (LK) and spontaneous regression. Based on the date of birth all children were divided according to seasons (winter, spring, summer and autumn) and periods of solar activity: reduced (winter-autumn) and increased (spring-summer) solar activity. Results. The study revealed a strong direct relationship between the outcome of retinopathy and gestational age and seasonal solar activity. Conclusion. In children born in spring and summer, the rate of spontaneous regression of retinopathy is significantly lowerthan in children born in the winter-autumn period. Reliable correlations were obtained: the longerthe gestational age and birth weight, the less likely it is to require laser coagulation.

The review discusses modern concepts of etiopathogenesis, clinic, diagnosis, treatment and preventive measures for optical neuritis, as well as the position of modern ophthalmology on the principles of management of patients with optical neuritis of various etiologies. The review includes 14 sources over the past 25 years from Russian (Elibrary CyberLeninka) and international (PubMed) databases.

The purpose of the study is to provide a method for repositioning intraocular lens (IOL) with suture fixation to the sclera in the projection of the ciliary furrow based on the example of a clinical case. The article presents the method for suture fixation of IOL dislocation (T-26 model). It describes a method of IOL reposition with suture fixation into the ciliary sulcus. Procedure stages: this method of IOL suture fixation is performed using two needles connected by a thread of polypropylene 10-0 (MANI sutures polypropylene 10-0). Using a guide needle 30G through the paracentesis, the needles are inserted above and below the IOL haptic element at the 6 o'clock position. The formed thread loop fixes the IOL in the projection of the ciliary sulcus to the sclera. Visual acuity on the first day after surgery was established at 0.7; IOP 19.0 mm Hg. At the control check-up after 7 days, visual acuity is 0.9 without additional correction; IOP 18 mm Hg. The proposed method of IOL reposition with suture fixation in the ciliary sulcus is associated with atraumatic, simple implementation and allows to achieve good functional and anatomical results in the treatment of patients.

The purpose of the study is to conduct comparative analysis of the two types of surgical approaches used in strabismus surgery: vertical and limbal L-shaped. Material and Methods. Analysis of surgical treatment of strabismus in 137 (205 eyes) patients aged 4 to 15 years was performed. During surgery, access to the surgical field was carried out by a vertical conjunctival incision in 143 cases (69.8%), by limbal incision — in 62 cases (30.2%). Results. Duration of hyperemia and edema in the group with limbal access is significantly shorter than in the group with vertical conjunctival access (12.2±0.14 and 24.5±0.15 days, respectively) (p<0.001). Reactions to suture material in the group with limbal access were shown only in 2 cases (3.2%), and in the group with vertical access — in 23 cases (16.1%) (p<0.01). Conclusion. An individual approach must be taken for each patient, taking into account the goals and scope of the procedure. When performing surgery on two adjacent muscles, preference should be given to conjunctival access, and when working on one muscle, to limbal access. For operations of the reinforcing type, it is preferable to use limbal access, and for weakening operations, it is more advisable to conduct conjunctival access. In children of a younger age group and in patients with a history of allergic reactions, it is better to conduct operations with limbal access.

The purpose of the study is to evaluate the relationship between the structures of the anterior chamber, disorders of the hydrodynamics of the eye and the work of the accommodation apparatus in patients with myopia. Material and Methods. The study involved 235 patients (235 eyes) with various degrees of myopic refraction. Patients are divided into 3 observation groups depending on the degree of myopia. Group 1 consisted of 103 patients (103 eyes) with mild myopia; group 2 consisted of 92 patients (92 eyes) with moderate myopia; group 3 consisted of 40 patients (40 eyes) with high myopia. Results. It was found that 95 patients with varying degrees of myopia (40.4%) had anterior chamber depth of more than 3.6 mm. During gonioscopy, goniodisgenesis was detected: in group 1 on 6 eyes (13%); in the 2nd group on 8 eyes (25%); in the 3rd group on 11 eyes (57%). A combination of increased corneal-compensated IOP of more than 21.0 mm Hg and habitual excess accommodation voltage (PINA) was recorded in group 1 in 1 case (2.3%), in group 2 in 3 cases (9.4%); in group 3 in 6 cases (31.5%). Conclusion. In myopic refraction, there is a syndrome of stretching of the anterior segment of the eyeball, which is more pronounced in high-grade myopia and is more often accompanied by ophthalmohypertension syndrome of overstrain of accommodation.

The purpose of the study is to evaluate the possibility of autofluorescence diagnostics (AFD)to determine the tumor boundaries and volume of surgery in patients with eyelid tumors of epithelial origin. Material and Methods. The study consisted of 3 parts: analysis of incidence of of eyelid basal cell carcinoma (BCC) recurrence; analysis of medical records of patients who underwent AFD at the primary visit for differential diagnostics between malignant and benign tumors; assessment of accuracy of determining tumor boundaries using visual diagnostics and AFD, based on the study of morphological sections of tumor fragments obtained after eyelid resection. Results. With 1.5 year follow-up period after surgical removal of BCC with visual diagnostics of its borders, the recurrence of the disease was verified in 18% patients. The use of AFD for differential diagnostics between malignant and benign tumors of eyelids skin and periorbital area showed that the method is effective for initial diagnosis of epithelial tumors in the outpatient unit. The AFD of the BCC boundaries compared with visual diagnostics is more accurate, it does not require long time and does not cause complications. Conclusion. The AFD can be used in ophthalmic oncology for early examination of the eyelid skin and periorbital area, it determines the boundaries of common pathological process more accurately, which guarantees complete removal of tumor and reduces the risk of its recurrence.

The purpose of the study is to determine the potential for diagnostics of human corneal endothelial cells functional activity based on a study of the transport of water and sodium ions by the endothelial cells of a pig's cornea. Material and Methods. The study was conducted on the disks of pig's cornea. Evaluation of cell volume dynamics was studied with a method based on fluorescence quenching effect of Calcein dye by cytoplasmic proteins. The intracellular sodium concentration was investigated by fluorescence microscopy method using sodium-specific dye Sodium Green. Micro-fluidic flow chamber was used to study the dynamics of corneal matrix deswelling. Results. Increase of temperature from 20 to 37° С activates Na/K-ATPase and leads to a decrease in the volume of corneal endothelium cells (characteristic time 73.5±12.6 s) (n=6). The relative concentration of intracellular sodium decreased with the characteristic time 130.0±26.3 s (n=5). Studies with temperature activation of endothelial cell pumping activity allowed us to estimate the initial rate ofthe matrix volume reduction: 0.36±0.006 um/s (n=5). Conclusion. The study of the dynamics of endothelial cells' volume and intracellular content of sodium in it during cold preservation allows to improve the quality of assessment of viability of a preserved cornea.

The purpose of the study is to analyze the processes of postoperative engraftment of various variants of a complex flap with a single-stage reconstructive blepharoplasty of perforating cicatricial eyelid defects. Material and Methods. The patients (40 eyes) who underwent a one-stage plastic reconstruction of cicatricial eyelid defects were divided into 2 groups depending on the variant of complex autograft: 20 patients 20 eyes with a three-layer flap in the main group, 20 patients 20 eyes with a double-layer in the control group. Evaluation criteria for the results were as follows: nature of complex autograft engraftment, cytological analysis of the wound exudate, clinical characteristics of the scar, size of the palpebral fissure, and microcirculation indexes. Results. 3 months after surgery the reparative process in 18 (90%) patients of the main group and in 15 (75%) patients of the control group ended with normotrophic scarring; in 2 patients (10%) of the main group there was pathological scarring, deviation in the size of the palpebral fissure was -9%; in 5 (25%) patients of the control group, we observed formation of complicated scars, deviation of palpebral fissure size was -22%. Conclusion. The main advantage of three-layer reconstructive blepharoplasty is the reduction in frequency of complicated scarring by 3 times. The mathematical algorithm that has been developed objectifies and individualizes the choice of the most rational surgical technology.

The purpose of the study is to define the dependence of choroid thickness (CT) from age and anteroposterior eyeball size (APES) in healthy persons. Material and Methods. We analysed data on 62 patients (62 eyes) aged 25 to 78 without retina and/or optic nerve pathology (45.5±1.7, M±m). Anteroposterior size of the eyeball was from 21.39 to 28.75 mm (23.97±0.18 mm, M±m). The examination included determination of the best corrected visual acuity, optical coherence tomography and optic biometry. Choroidal thickness was measured on two B-scans (vertical and horizontal) in the projection of the fovea and at 24 points from the fovea (in the superior, inferior, nasal and temporal sections) with an interval of 500 urn from each other. Results. CT is predominantly thinner peripapillary and in the inferior section of retina (p<0.01). CT is inversely proportional to the anteroposterior eyeball size (p<0.01). Calculation formula and a chart map of normal values of the choroid thickness depending on APES are proposed. Dependence on age was statistically unreliable (p=0.68). Conclusion. A method for calculating individual values of the choroidal thickness depending on the anteroposterior eyeball size is proposed. This method can be applied in practice in the diagnosis of pachychoroid diseases.