The causes of bruises under the eyes are divided into physiological and pathological factors, as follows: 1. Physiological factors: Mostly due to the thin skin of the lower eyelid, the veins under the skin under the eyes stand out and show bruise-like changes, this is a physiological phenomenon, physical health, and not a disease, especially in some children and women, the lower eyelid skin is thinner and more likely to have bruises under the eyelids. The eyelid is also the most exposed part of the body, with loose subcutaneous tissues and thin skin, so the distribution of blood vessels is more superficial, and you can see the blood vessels going through the skin; 2. Pathological factors: If the bruises are not linear, but lump-like, and the phenomenon gradually worsens with time, it is recommended to go to the hospital ophthalmology for examination in time, and you can do orbital Ultrasound to see if the formation of orbital hemangioma is the cause; 3, other: long-term stay up late, poor sleep, poor rest, drinking alcohol and other causes of vascular expansion, will also make the symptoms of bruises under the eyelids more obvious.