Entropion is the medical term for an eyelid that turns inward. It can be caused by the loosening of tissues of the lower eyelid, eyelid muscle spasm, or scarring. It can lead to significant irritation and tearing of the eye as this typically causes the eyelashes of the lower eyelid to rub on the eye. This can permanently damage the surface of the eye. It is corrected surgically by tightening and rotating the lower lid outward.