[Concentration of VEGF-A in the intraocular fluid of rats with alloxan model of diabetes mellitus]. / Kontsentratsiya VEGF-A vo vnutriglaznoi zhidkosti krys s alloksanovoi model'yu sakharnogo diabeta.

PURPOSE: To study the changes in the concentration of vascular endothelial growth factor A (VEGF-A) in the intraocular fluid (IOF) of rats with alloxan model of diabetes mellitus (DM) on insulin therapy at different time points. MATERIAL AND METHODS: The alloxan model of DM was simulated in 197 rats by a single intraperitoneal injection of 100 mg/kg alloxan hydrate. The animals were divided into 3 groups 7 days after administration of alloxan hydrate. The main group consisted of animals with alloxan model of DM, which begain receiving single daily intraperitoneal injections of insulin at a dose of 0.9 U/kg body weight. The comparison group included animals with alloxan model of DM, which did not receive the therapy. The control group consisted of healthy animals. The experimental animals were withdrawn from the study 1 and 4 months after the start of insulin therapy. The concentration of VEGF-A was determined in 80-90 µL of intraocular fluid collected from both eyes of each animal. RESULTS: At 1 month, the VEGF-A concentration in the intraocular fluid in the study group (n=17; 140 [136; 210] pg/mL) was statistically significantly higher than in the comparison group (n=20; 72 [58; 86] pg/mL; pm-u<0.0004), and in the control group (n=16; 76 [62.5; 88] pg/mL; pm-u=0.0045). The comparison group did not have statistically significant differences from the control group (pm-u=0.9979). At 4 months, the VEGF-A concentration in the intraocular fluid in the study group (n=18) was 84.8 [61.1; 93.2] pg/mL, in the comparison group (n=16) - 66.4 [54.4; 73.75] pg/mL. The VEGF-A concentration in the intraocular fluid in the study group at 4 months was statistically significantly lower than in the study group at 1 month (pm-u<0.0044). CONCLUSION: Insulin therapy causes a statistically significant increase in the concentration of VEGF-A in the intraocular fluid of rats with alloxan model of DM after 1 month, but after 4 months of the therapy the VEGF-A concentration falls back to the initial values.

[Effect of acute insulin therapy on the concentration of vascular endothelial growth factor A (VEGF-A) in the intraocular fluid in an experiment]. / Vliyanie kratkosrochnoi insulinoterapii na kontsentratsiyu sosudistogo endotelial'nogo faktora rosta A (VEGF-A) vo vnutriglaznoi zhidkosti v eksperimente.

PURPOSE: To study the effect of insulin therapy on the concentration of vascular endothelial growth factor A (VEGF-A) in the intraocular fluid of rats with alloxan model of diabetes mellitus. MATERIAL AND METHODS: The experiment was conducted on 80 mongrel rats. In 65 rats, the alloxan model of diabetes mellitus was simulated by a single intraperitoneal injection of 100 mg/kg alloxan hydrate saluted in 0.4 ml of citrate buffer. 72 hours after intraperitoneal administration of alloxan monohydrate, these animals were divided into 2 groups. The main group (group 1) consisted of animals with alloxan model of diabetes mellitus, who started daily single intraperitoneal administration of prolonged-acting insulin at a therapeutic dose of 0.9 U/kg Body weight. The comparison group (group 2) consisted of animals with alloxan model of diabetes mellitus who did not receive specific therapy. 15 healthy rats constituted the control group (group 3). Experimental animals were removed from the study on day 31 of insulin therapy. The concentration of VEGF-A was determined in 80-90 µl of intraocular fluid collected from both eyes of each animal. RESULTS: In the main group, the median of VEGF-A concentration [25th; 75th percentiles] in the intraocular fluid was 140 [136; 210] pg/ml, which is 1.94 times higher than in the comparison group (72 [58; 86] pg/ml) and 1.84 times higher than in the control group (76 [62.5; 88] pg/ml). The concentration of VEGF-A in the intraocular fluid in the main group was statistically significantly higher, as compared with the comparison group (pm-u<0.0004), and compared with the control group (pm-u=0.0045). The comparison group had no statistically significant differences when compared with the control group (pm-u=0.9979). CONCLUSION: Insulin therapy for 31 days increases the concentration of VEGF-A in the intraocular fluid of rats with alloxan model of diabetes mellitus.

[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.