The bluing of the baby’s lower eyelid may be caused by physiological reasons such as thin skin, lack of sleep, etc. It may also be caused by pathological reasons such as ocular trauma, conjunctivitis, etc. The baby’s lower eyelid may be bluing because the skin is thin and the veins of the eyelid are rich. 1. Thin skin: Because the skin of the baby’s eyelids is very thin, and the eyelids are rich in venous blood vessels, so the baby can appear in the lower eyelids of the blue performance, and there is no other discomfort, is a normal performance. 2. Lack of sleep: When the baby is too tired or sleeps too little, the baby’s eyelids will have blood stagnation, and the baby’s lower eyelids will be blue, i.e. dark circles under the eyes. 3. Ocular trauma: If the eyelids of a child with ocular trauma are hit or bumped, causing bruising of the lower eyelids, the child may have a blue lower eyelid. 4. Conjunctivitis: If the baby has allergic conjunctivitis, repeated rubbing and blinking of the eyes may also cause localized vasodilatation and bruising, resulting in a bluish appearance. It is recommended that children with significant lower eyelid bluing and other discomforts should seek prompt medical attention to assess their condition and follow the doctor’s instructions for treatment.