Dark circles are mostly caused by blood in the eyes. Ultrasound can promote blood circulation of eye skin and reduce blood, so it can obviously improve dark circles. In addition, the bags under the eyes themselves can also cause dark circles. When the bags under the eyes bulge, especially when the light shines from above, the dark circles are particularly obvious. After the bags under the eyes are completely removed, the bulging bags under the eyes will disappear, and so will the dark circles. For dark circles caused by dark skin, ultrasound can inhibit melanocytes and reduce melanin secretion, thus reducing dark circles. Therefore, removing the bags under the eyes by ultrasonic wave can obviously improve the dark circles.