There is not yet a proven way to prevent cataracts. Doctors do not yet know much about why cataracts develop, however, it has been hypothesized that there are certain risk factors that could be involved. It is suggested that you try to avoid risk factors such as, smoking, long-term exposure to sunlight, and excessive alcohol consumption. There are also mixed ideas on the involvement of an antioxidant-rich diet in preventing or slowing cataracts, but this has yet to be proven.
The best thing you can do is to have regular eye examinations to help detect cataracts at the earliest stages