Well, it often happens to some people who keep smoking to have bloodshot eyes. As we know that by smoking, it can cause a complex interaction between your body and the same kind of chemical reaction that produces bruises. And in that way, it can make your blood pressure high. Then, this lead to high eye pressure. It results in your bloodshot eyes. So if you do not want to have the bloodshot eyes, you should quit smoking. If you keep smoking, it actually does harm to your health, not only the eyes, but also the body organs. As we know that by smoking, it can produce cyanide which is a retinal toxin. And according to some research, Smokers may develop toxic amblyopic problem. And also, it can degrade the night vision. So it can be kind of dangerous.