I. What is an arcus? Ingrown eyelashes are eyelashes that grow toward the eye and touch the cornea and conjunctiva. Under normal circumstances, the eyelashes should be fully extended forward and not in contact with the cornea. Ingrown eyelashes are often accompanied by an entropion of the lid. What are the common causes of baby’s ingrown eyelashes? Ingrown eyelashes in infancy are often caused by congenital lid entropion, mostly in the lower lid. Most congenital lid entropion is caused by an inner canthus, overdevelopment of the orbicularis muscle at the lid margin, or underdevelopment of the lid plate. What are the common clinical manifestations of baby entropion? As the eyelashes rub back against the cornea, it can cause damage to the epithelium of the conjunctiva and cornea. The baby’s eyes often show signs of photophobia, tearing, and increased secretions (also known as “eye drops” and “eye mucus”). How can parents tell if their baby has impingement? The baby’s eyes (especially the inner corners of the eyes) are teary. With the naked eye, you can see that the eyelashes on the lower lid are growing toward the eyeball, and some of them touch the eyeball in pieces. Do I need surgery for my baby’s ingrown eyelashes? The treatment options for baby’s ingrown eyelashes are different for each baby’s eye condition. 1. If the number of baby’s ingrown eyelashes is small or the eye symptoms are not obvious, surgery may not be needed, because most of the baby’s ingrown eyelashes are often caused by inversion of the lid (often due to the lower lid ingrown eyelashes or lower lid inversion caused by the child’s fat and underdeveloped nasal root). There is a tendency for self-healing, so there is no urgency for surgery. 2. If the impingement touches the eye and causes discomfort such as foreign body sensation, photophobia, and tearing, surgery is needed to correct the lid entropion for the purpose of treating the impingement. A common surgical procedure is lower lid sutures to correct entropion (this procedure is easy to perform, has no surgical incisions and does not require stitch removal).