By the direction of the squinting eye (ie the eye not looking perfectly in the direction of gaze):.Squints can be classified or described in various ways, including There are several different types of squint (strabismus). If this doesn't happen, either because the eye muscles on one side don't receive exactly matching signals from the brain, or because the eye muscles respond unequally to those signals, then the eyes will not point in a perfectly matching direction. In order for both of our eyes to turn to look at the same thing, we need the eye muscles on one side to coordinate perfectly with the eye muscles on the other side. For example, to look to the left, the lateral rectus muscle of the left eye pulls the left eye outwards and the medial rectus muscle of the right eye pulls the right eye inwards towards the nose. The superior oblique muscle tends to make the eye look downwards towards the mouth and, together with the inferior oblique muscle, stops the eye rotating around the pupil as the other eye muscles work.The inferior oblique muscle tends to turn the eye outwards and upwards.The inferior rectus muscle pulls the eye downwards and slightly inwards.The superior rectus muscle pulls the eye upwards and slightly inwards.The medial rectus muscle rolls the eye inwards, turning the gaze towards the nose.The lateral rectus muscle rolls the eye outwards, turning the gaze outwards.

The eye is a ball in a socket, and each muscle actually 'rolls' the eye in its socket, allowing us to look in multiple different directions.

Shut in syndrome