If a painless mass in the neck is found in early infancy and ultrasound confirms that it is in the sternocleidomastoid muscle, myotonic squint can be diagnosed as an early manifestation. If the squint is not corrected around 1 year old and the sternocleidomastoid muscle on the affected side is obviously tense after the head is righted, surgery is needed. Myotonic squint can be treated conservatively if the child is not old enough for surgery, in order to avoid surgery as much as possible.