Cataract is the major cause of blindness in man throughout the world. It is usually dealt with by surgery but surgery is expensive and may lead to other ocular damage. Apart from surgery one might hope to prevent cataracts or to cure them, but these approaches require a much greater understanding of the structure and metabolism of the lens and of its weaknesses and strengths. The emphasis of this book is on recent findings. The first chapter deals with the normal lens and its structure, cellular composition, metabolism and proteins. In the following chapter the ageing of the lens will be discussed, and the third chapter discusses the epidemiology of cataract emphasizing the size of the problem of cataract and the associated risk factors. Surgery is discussed briefly but without detailed discussion of recent changes in surgical procedure. That is followed by a chapter on experimental cataracts and related in vitro studies. The studies of human cataracts are discussed in chapter 5. The last chapter deals with the prevention of cataract and its delay by anti-cataract agents. There have been advances in this area recently and there is the promise of an effective therapeutic treatment soon.