This study which began in Jan 2005 will look into age-related cataract, where the lens within the eye becomes cloudy. This is the commonest cause of visual loss worldwide, causing blindness in 25 million people. Current surgical treatment is successful but is usually late as well as being too expensive for many countries. In previous groundbreaking research, we showed that genetic effects are a very important factor. Identifying susceptibility genes for age-related cataract will facilitate our understanding of epidemiological factors and vital gene- environmental interactions that determine the disease process.