Cataract accounts for almost half of the world’s blind population (Kupfer 1984, Thylefors et al. 1996) and is the most common cause of correctable blindness (Dawson & Schwab 1981). The World Health Organisation (Enoch et al. 1993) has estimated that there are 17 million people worldwide blind due to cataract. With an ever ageing population this number may grow to 40 million by the year 2025, as developing countries cope with both the backlog and the new cases. It has been calculated that if the onset of cataract were delayed by 10 years, the number of cataract operations needed would decrease by 45% (Thylefors 1990). Many risk factors for cataract have been suggested.