[Parameters of oxidative stress in the lens, aqueous humor and blood in patients with diabetes and senile cataracts].

INTRODUCTION: Contemporary hypothesis considers the oxidative stress as a crucial event in age-related processes in the body, as well as in the age-related cataract formation. Disturbance of balance between oxidative processes and antioxidative defenses causes the oxidative stress that can damage proteins, lipids, polysaccharides and nucleic acids. The secondary aging factors accelerate ageing processes. One of them is diabetes. It's numerous consequences that appear in the eye are well known.

PURPOSE: The purpose of this paper is to analyze influence of the non-insulin-dependent diabetes (Type II) on cataract genesis mainly through action of the oxidative stress and antioxidative defense.

MATERIAL AND METHODS: Here were analyzed contents of the lipid oxidation products (lipid peroxides--LP) and total sulfhydryle groups (TSH) in the lens' corticonuclear blocks and antioxidative capacity in their humour aqueous expressed as percent of induced malondyaldehyde (% iMDA) in 14 samples obtained from patients with cataract and diabetes mellitus type II (without diabetic complications; duration of diabetes was 0-17 years) and compared to 66 samples of patients with cataract without diabetes, as well as some parameters of the oxidative stress in serums (content of vitamin C, acrobat--A, dehydroascorbate--DA and their relation, vitamin E, glutathione--GSH, peroxidase--P and catalase--Cat activity, content of malondyaldehyde--MDA and % iMDA) of 27 patients with age-related cataract and diabetes mellitus type II (without complications; same duration), and compared to the other 135 age-related cataract patients. Data were analyzed by multivariant and univariant analysis of variance (multivariant t-test, MANOVA and ANOVA). Also were analyzed frequencies of the secondary serium diseases in a clinical group of 162 patients with cataract and sex and age matched 55 examined people without cataract, as a control group, by a logistic regression.

RESULTS: Patients with diabetes and cataract have lower values of almost all investigated parameters of antioxidative defense in their serum and higher level of the lipid peroxidation products (multivariant: p > 0.05). Level of glutathione in their serums is significantly lower (t = 2.27; p = 0.028). Intensity of lipid peroxidation in corticonuclear lens blocks is higher in patients with diabetes, whereas their total sulfhydryle groups and % iMDA in humour aqueous shows lower antioxidant capacity in the same group, probably because of higher intensity of oxidative stress, although not significantly (T = 2.23; F = 0.95; p > 0.05; univariant: p > 0.05). Also, by investigation of frequencies of the secondary ageing diseases in patients with age-related cataract and age and sex matched control subjects, by a logistic regression was found high odds ratio for diabetes (?2 = 18.87; p = 0.0044; const = 0.379; OR = 2.506).

DISCUSSION: Statistically lower level of the serum glutathione in diabetic patients is important index of higher level of oxidative stress in their organism. Values of other investigated parameters of oxidative stress and antioxidative defense point to the some process. However, serum's parameters are not quite specific to the cataract, because active homeostatic mechanisms at the level of hematocamerular barrier and lens' metabolism could maintain local environment to the some extent. Yet, importance of glutathione level and metabolism of the eye's lens is great. Similar meaning bear the other sulfhydrile groups, i.e. of the lens' proteins-crystallines. So, total sulfhydrile groups level is good mark for the lens antioxidative defense, as well as the lipid peroxides are good mark for the intensity of oxidative processes. Percent of induced MDA in humour aqueous may be considered as the rest of antioxidative defense, similar to it's meaning in serum. Intensity of the oxidative stress in local compartment in diabetic patients in this paper is higher, compared to other age-related cataract patients without diabetes. Lack of significance could be explained by mentioned characteristics of the group (i.e. diabetics without complications), compared with other authors results, whose examined patients have had proliferative diabetic retinopathy. The odds ratio value of diabetes to the age-related cataract also confirms that diabetes is a risk factor for the age-related cataract genesis.

CONCLUSION: Results confirm hypothesis of the oxidative stress role in the age-related cataract genesis, especially in patients with diabetes mellitus. Parameters of their antioxidative defense are lower and those of oxidative stress are higher in serums and in the lenses and humour aqueous. They also point to the dynamics and diversity of oxidative stress and antioxidative defense in different compartments of the body, as well as their different meaning in distinct physiological and pathological conditions.