The most obvious sign of a squint is eyes that look in different directions. Squints can also cause: double vision; lazy eye(amblyopia) in young children where the vision is poor in the eye with the squint; and a squint can cause people to develop an abnormal position of the head.

If a squint is left untreated in young children, a lazy eye (amblyopia) can develop. The vision in the affected eye gradually deteriorates because the brain ignores the weaker message being sent from that eye. A lazy eye can be treated up until about six or seven years of age, but it must be treated as soon as possible.