Strabismus, also known as a squint, is a condition where the eyes are not looking in the same direction. While one eye looks straight ahead, the squinting eye may turn inwards (convergent squint), outwards (divergent squint), upwards or downwards.

Illustration: Inward drifting of the right eye (Convergent squint)

Illustration: Outward drifting of the right eye (Divergent squint)

Strabismus can develop at any age, it might be present within the first few months of life or only occur in adulthood. The drifting of the eye may be present all the time or may only be observed  intermittently, occurring in certain situations like when the individual is tired, daydreaming, or looking into the distance or reading. The eye that is drifting may always be the same eye or alternate between each eye.

Having strabismus may also result in poor depth perception and an inability to appreciate 3-dimensional images. Children with squints can also develop lazy eye (medically termed "amblyopia") where vision in the eye fails to develop properly.