Well, yes, eye strain can lead to dark circles under eyes. And, when your eyes suffer eye strain, it will just make some disorders in your eyes. And in that way, dark eyes can be caused. To treat it, you should try some ways to decrease the eye strain. For example, you can just have some eye exercises, and also do not overuse your eyes in a long time. Also, according to some experts, camellia oil is very good for the dark circles under my eyes, because of the elements in them. They are just like many other oils which are not just beneficial for the body health, but also do a good job to the dark circles under eyes. By the way, you should stay away from the stress and Caffeine. Anyway, just be careful about it.