A line on the lower eyelid may be caused by heredity, or it may be caused by over fatigue and ageing. 1. Genetic factors: If parents have obvious wrinkles on the lower eyelids, their offspring may have eyelid wrinkles due to genetic factors, mostly symmetrical and regular contour lines, which are generally physiological phenomena that do not require special treatment. 2. Excessive fatigue: People who often stay up late, do not get enough sleep, and have excessive eye fatigue are prone to eye bags, which can cause a line to appear on the lower eyelid, and patients need to adjust their work and rest or avoid eye fatigue and other improvements. 3. Ageing: As people age, the skin around the eyes loosens and wrinkles tend to appear, causing a line to appear on the lower eyelid. It is recommended that patients with lower eyelid anomalies seek medical attention to evaluate their condition and follow the doctor’s instructions for appropriate treatment.