Current Concepts of Molecular Mechanisms of Age-Related Changes in Eye Lens

Abstract

Age-related cataract is the leading cause of vision loss in old people worldwide. According to the World Health Organization it accounts for 47.8 % of the total number of ocular pathologies in people over 50 years old. Despite the rapid development of cataract surgery technology, surgery remains a challenge due to its cost and the increasing number of patients. Literature review is devoted to current concepts of pathogenesis and molecular mechanisms of age-related changes in eye lens. There are the three main theories of cataractogenesis: oxidative stress; the impact of quinoid substances, which are formed due to the impairment of aromatic amino acid metabolism and the activation of aldo reductase enzyme with subsequent accumulation of sorbitol, reactive oxygen species (ROS) generation, dysfunction of Na+/K+ channels and calcium deregulation causing lens epithelial cells apoptosis. Theories of pathogenesis are linked and based on the development of age-related changes in protein metabolism (the majority of nuclear α-crystallins are insoluble), glucose metabolism (non-enzymatic glycosylation of proteins), lipid metabolism, enzyme activity and the loss of membrane potential of cells ( the increase of Na+ and Ca2+ level and the decrease of K+ level). Key element of all theories of age-related changes in eye lens is the aggregation of high molecular weight proteins covalent-bonded of disulfide linkages. Based on molecular mechanisms of cataractogenesis, the development of pathogenetically oriented medical methods of correction of the age-related changes in lens is carried on. This review provides information on results of experimental and clinical studies which demonstrate the anti-cataract effect of Pirenoxine 0, 005 %.