Well, black eye occurs when blood and other fluids collect in the space around the eye. And for the causes, it is often caused by the injury to the face or the head. In common, because of the stroke or injury, swelling and dark discoloration can be possible. Of course, according to some researches, the tea tree oil is very good for black eyes, for tea tree oil contains a cosmetic product and purcelin oil that can help improve the appearance of scars, stretch marks. In that way, it will do a good job to black eye. By the way, you can try using ice to reduce the swelling caused by a black eye. In this way, the bruising will start fading in a few days. Anyway, just have a try.