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Background. The role of metabolic changes in the anterior eye tissues in the pathogenesis of uveal inflammation in patients with elevated intraocular pressure has been studied poorly. Of particular interest, in this respect, are free radical mechanisms, which can be a trigger of oxidant stress and cause damage to cell membranes in ocular tissues. Purpose. To study the activity of pro-oxidant enzymes and levels of lipid peroxidation products in the uvea tissues in the rabbits with experimental anterior non-infectious uveitis against the background of ocular hypertension. Material and Methods. Forty-one rabbits were divided into 4 study groups. Group 1: 10 animals with experimental ocular hypertension; group 2: 10 animals with experimental allergic uveitis; group 3: 12 animals with ocular hypertension and allergic uveitis; and group 4: 9 intact animals serving as controls. To simulate ocular hypertension in the groups 1 and 3, the animals were made a single 0.1 ml injection of 0.3% carbomer into the anterior chamber. The tissues of the uvea and the aqueous humour were studied biochemically. We estimated the activity of pro-oxidant enzymes, NADPH oxidase and xanthine oxidase, and the content of lipid peroxides: malonic dialdehyde and diene conjugates. The data of the experimental studies were processed using parametric statistical tests with an SPSS package and Statistica 5.5 Results. The activity of pro-oxidants enzymes was increased in all uvea tissues in all study groups; the maximal NADPH oxidase and xanthine oxidase activity was in the animals with both ocular hypertension and uveitis. The NADPH oxidase and xanthine oxidase activity was increased by 51.1% and 63.9% (р<0.001), respectively, as compared with controls. Lipid peroxidation with accumulation of toxic products in the uvea and aqueous humour was noted both in the ocular hypertension-only and uveitis-only groups; however, the maximal values were in an uveitis model against the background of ocular hypertension, where malonic dialdehyde and diene conjugates were increased, respectively, by 67.0% and 54.3% (р<0.001) in the aqueous humour, and, respectively, by 93.1% and 69.1% (р<0.001) in the uvea tissues, compared with controls. Conclusions. Our findings reveal an important link in the pathogenic action of elevated IOP which burdens inflammation in the uveal tissues through the activation of oxidative and peroxidative processes. In addition, our findings support the assumption that primary high-pressure glaucoma can be a factor which worsens inflammation in the anterior eye.

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To determine the features of the microstructure of choreoretinal complex in rats with diabetes induced by streptozotocin in the presence of axial myopia. Material and Methods: Fifty-five Wistar rats (110 eyes; age, 2 weeks to 14 weeks) were used in experiments. Four groups were formed: group 1 (axial myopia only); group 2 (diabetes only); group 3 (both myopia and diabetes); and group 4 (controls; intact animals). High form-deprivation myopia was produced in two-week animals by surgically fusing the eyelids of both eyes and these animals were maintained under conditions of reduced illumination for two weeks to induce a more intense myopization of the globe. Eyelid sutures were removed on completion of these two weeks. Two weeks thereafter, type 2 diabetes mellitus was induced in rats with induced axial myopia and intact rats. A 50 mg/kg intraperitoneal streptozotocin injection for 5 days was used for this purpose. Elongated axial length and increased anterior chamber depth as measured by in vivo ultrasound were an objective criterion of the development of myopia in experimental animals. A glucose level of ≥ 4.5 mmol/L was a criterion of the development of diabetes. Two months after inducing diabetes, 14-week rats were sacrificed, and their eye tissue samples were processed by a routine method and assessed by electron microscopy. Ultrastructure of the choroid, RPE, and retinal photoreceptor cells were examined. Ultra-thin sections were cut, stained with lead citrate according to the procedure described by Reynolds, and observed with a PEM-100-01 Transmission Electron Microscope. Results: Our ultrastructural study found that myopization of the rat globe with elongation of the axial length somewhat reduced the severity of some ultrastructural changes in the choreoretinal complex in induced type 2 diabetes due to reduced choroidal swelling and dominance of compensatory processes with increased energy producing, protein synthesis and other functions in the endothelial vessels and choriocapillaries as well as RPE cells. Out findings seem to corroborate the concept that myopized eyes have capacity to somewhat buffer the development of severe diabetic retinopathy, likely due to some compensatory-andrestorative processes.

Background:We have previously demonstrated that the course of inflammatory process was significantly more severe in eyes with anterior uveitis with ocular hypertension (OHT) than in those with anterior uveitis with normal intraocular pressure (IOP), which was largely due to a more marked activation of enzymes producing active oxygen as well as peroxidative processes in uveal structures of experimental animals. Aside from oxidative stress characteristics, our attention has been drawn to neopterin as a potential marker of inflammation severity and the efficacy of inflammation control. Because there is a paucity of reports focused on the potential for using this characteristic as a diagnostic criterion in ocular disorders, especially in uveitis with raised IOP, studies on this subject are important. Purpose: To assess the impact of dipeptide carnosine on the level of neopterin in the rabbit's anterior eye segment in anterior uveitis with ocular hypertension. Material and Methods: Forty-four Chinchilla rabbits (88 eyes) were divided into 4 experimental groups (group 1, 10 animals with induced OHT only; group 2, 10 animals with induced experimental non-infectious uveitis only; group 3, 12 animals with OHT induced prior to experimental non-infectious uveitis; group 4, 12 animals treated with carnosine for experimental uveitis with OHT). Rabbits of group 4 received 5% carnosine solution into the conjunctival sac, twice daily for the four weeks. The control group comprised 9 intact rabbits. Neopterin enzyme-linked immunosorbent assay kit was used to determine neopterin levels in uveal tract tissue, aqueous humor and tear samples according to the manufacturer's instructions. Statistica 5.5 (StatSoft, Tulsa, OK, USA) software and parametric statistical tests were used for statistical analysis. Results: Neopterin levels in uveal tract tissue, aqueous humor and tear samples taken from rabbit's eyes with induced OHT only were increased compared to controls but lower than those in non-infectious uveitis only. Neopterin levels in uveal tract tissue, aqueous humor and tear samples from rabbit's eyes with induced both anterior uveitis and OHT (group 3) were 5. 2-, 3.7-and 2.4 times higher, respectively, than in controls, and 42.5% (р < 0.05), 28.5% (р < 0.05) and 23.6% (р < 0.05) higher, respectively, than in samples taken from rabbit's eyes of group 2. The carnosine treatment of induced both anterior uveitis and OHT (group 4) contributed to reduced levels of neopterin is samples under study, with neopterin levels in uveal tract tissue, aqueous humor and tear fluid being 39.4%, 38.9% and 30.2% lower, respectively, than in samples taken from rabbit's eyes of group 3 (anterior uveitis plus OHT without treatment) (р < 0.01), and 3.2-, 2.2-and 1.7 times higher, respectively, than in controls (р < 0.001). Conclusion: High neopterin levels in the uveal tract tissues and anterior chamber aqueous fluid indicated its impact on the course of inflammation in animals with induced uveitis only and especially in those with induced both uveit...