Though you can't prevent glaucoma, you can maintain a healthy lifestyle to reduce the risk of getting glaucoma. For example, you should avoid smoking and excessive alcohol and often exercise to keep your weight down.
There is no way to prevent or reduce the risk of getting glaucoma. The only way you can do is to take regular eye exams so that you can know whether you have developed glaucoma early. If it is detected early, it can be treated more successfully.