Clouded vision causing blindness, what could this be?

Many questions: Is this recent or a gradual loss? Is it one eye or both eyes? Is there a history of trauma, eye disease or systemic disease? Are you on medications for non-eye problems? Is the vision loss silent, or are the eye(s) in pain, and getting red? For most of these, you need to have an ophthalmologist evaluate your eyes and hopefully can intervene to prevent loss of vision.