摘要:The aim of the study was to determine the activity of cytochrome c oxidase in mitochondrial fractions of cataractogenic epithelial cells of lenses of 60 patients (34 females and 26 males). According to clinical criteria patients were divided into three groups: group 1 – patients with senile cataract, group 2 – active smokers with senile cataract, and group 3 – diabetic patients with cataract as diabetic complication. In the extracted lenses we determined the absorption activity of mitochondrial enzyme cytochrome c oxidase. Biochemical researches using the method of Yonetani and Ray13 were applied. We also applied the statistical Student t-test (p with three parameters and Snedecor F distribution (s = p cytochrome c oxidase in mitochondrial fraction of lens epithelial cells is twice as low in patients who are active smokers than in the non-smoking patients with senile cataract. We measured a significantly different activity of cytochrome c oxidase between active smokers and the non-smoking patients with senile diabetic cataract (tp Cigarette smoke decreases the activity of cytochrome c oxidase in mitochondrial fraction of lens epithelial cells. This enzyme is a terminal oxidase in the synthesis of ATPs. We suggest that smoking decreases the synthesis of energy in the lens of cigarette smokers. This emphasizes the significance of giving up smoking in order to preserve the structure and function of the lens.