Age-related nuclear cataract: A lens transport problem

Age-related nuclear cataract is a major cause of blindness. It is character ised by opacification and colouration in the centre of the lens and is acco mpanied by extensive protein oxidation. The reason for the onset of nuclear cataract is not known, but it is proposed here that the underlying cause i s the development, with age, of a barrier to the transport of metabolites w ithin the lens. Such a barrier may result in an increase in the half-lives of reactive molecules, such as UV filters, thus promoting posttranslational modification of proteins in the nucleus and may also act to prevent an ade quate flux of antioxidants from reaching the lens interior and, as a conseq uence, allow oxidation of nuclear components. Further, this oxidation may t ake place even if the lens outer cortex and epithelium remain perfectly fun ctional. Copyright (C) 2000 S. Karger AG. Basel.