Children’s lower eyelid bluing may be caused by physiological reasons, trauma, cardiovascular disease. 1. Physiological reasons: children are in the stage of growth and development, due to the relatively thin skin and subcutaneous fat, if the blood vessels under the skin are penetrated, the phenomenon of lower eyelid bluing may occur. In addition, if children stay up late for a long time, are overworked, or do not get enough sleep, the lower eyelids may also turn blue. 2. Trauma: If a child’s lower eyelid has recently suffered a traumatic injury such as a collision or blow from the outside world, it can easily lead to bruising of the tissues under the eye, causing the lower eyelid to turn blue. 3. Cardiovascular disease: When children suffer from congenital cyanotic heart disease, the lower eyelid skin may also appear blue, accompanied by lips, cyanosis of the skin around the mouth. After children’s lower eyelids are blue to rule out physiological causes, parents should take their children to the hospital in time to assess their condition and follow the doctor’s instructions for treatment.