It is found that cataract is the result of oxidation in the eyes. This process is much faster when too much UV rays are absorbed by lens. However, UV rays are harmful and lens tends to find some way for protection- a kind of cloudy substances is formed, so as to avoid more UV rays. Ultimately, people can not see gradually. Luckily, decent amount of Vitamin C can benefit people a lot in slowing down or preventing the occurrence of cataract.