Normally the two eyes move parallel to each other in all the directions of gaze.

Squint is a misalignment of the two eyes so that both eyes are not looking in the same direction. In other words the two eyes don’t look straight in the primary gaze. It is a common condition among children. It may also occur in adults.

At birth the eyes don’t move together. One eye moves differently from the other till the first few months. After that the baby starts fixing the eyes on the light which is called light fixation and the eyes start moving together.

Under normal circumstances, when both the eyes have good vision and they are aligned properly, they focus on the same object. Each of the eyes sends picture of the same object, viewed from a slightly different angle. These two images reach the brain, where they are fused to form a single three-dimensional picture with depth perception. This is known as binocular single vision.

Six muscles control the movement of each eye. Each of these muscle acts along with its counterpart in the other eye to keep both eyes aligned properly. A loss of coordination between the muscles of the two eyes leads to misalignment. This misalignment may be the same in all directions of gaze, or in some conditions the misalignment may be more in one direction of gaze.

Squint may be:

Paralytic Squint: Means one of the muscle attached to the eyes is paralyzed and the eye affected may turn in/out/up/down depending on the muscle involved i.e. the eye movement is restricted in the direction of the action of the paralyzed muscle. This can be caused by direct trauma to the muscle as for e.g. injury during forceps delivery or any other injury. It may also be caused by certain nerve palsies, which in turn may be caused by peripheral neuritis or diseases of the CNS, e.g. meningitis, encephalitis etc. Treatment of paralytic squint depends on the cause and many a time paralytic squint may not be completely cured. In such cases spectacles with prisms are prescribed.

Non Paralytic Squint: A loss of coordination between the muscles of the two eyes leads to misalignment. This misalignment may be the same in all direction of gaze, or in some conditions the misalignment may be more in one direction of gaze.

The squint is diagnosed by the ophthalmologist. He or she would do a few special tests (Cover – Uncover Tests) to confirm the squint, to try and find out the cause and to quantify the amount of derivation. In some cases there may be a false appearance of squint due to broad nasal bridge in a child. An ophthalmologist will be able to differentiate between a true squint and false squint.


Last updated on 14-05-2001