A squint, also known as strabismus is a condition in which the eyes do not align properly, one of them turns inwards, upwards, downwards, or outwards while the other one focuses at one spot. Typically, the extraocular muscles are not working in coordination, resulting in each eye unable to gaze at the same spot at the same time.

If both eyes are not completely aligned, binocular vision is not possible, making it harder for the person to appreciate depth perception.

Strabismus can also be caused by a disorder in the brain which cannot coordinate the eyes correctly.

According to the National Health Service (NHS), UK, squints affect approximately 5% of children and usually develop during their first 36 months of life (sometimes later). Squints are sometimes identified in infants a few days after they are born.

Four types of squints:

• The eye turns inwards - Esotropia
• The eye turns outwards - Exotropia
• The eye turns upwards - Hypertropia
• The eye turns downwards - Hypotropia

People can also have persistent or intermittent squints.

The earlier in life a squint can be identified and treated, the more effective that treatment is likely to be. A squint, if left untreated, can eventually develop into lazy eye (amblyopia), in which the brain starts ignoring input from one of the eyes. The brain ignores one of the eyes to avoid double vision.

If a child has poor vision in the squinting eye, wearing a patch over the other eye might help the squinting eye's proper development.

Sometimes a squint comes back later in adulthood, even though it had been successfully treated when the patient was a child. In such cases the adult may have double vision, because by that time the brain is trained to gather data from both eyes, it cannot ignore one of them.

According to Medilexicon's medical dictionary:

Strabismus is "A manifest lack of parallelism of the visual axes of the eyes."

What are the signs and symptoms of a squint (strabismus)?

The sign of a squint is fairly obvious - one of the eyes does not look straight ahead, but veers. Some people may have minor squints that are less noticeable.

Infants (newborns) may go cross-eyed, especially if they are tired. This does not mean they have a squint. Concerned parents should check with their doctor.

If you notice that your child has one eye closed, or turns his/her head when looking at you, this could be a sign of double vision, and a squint is possible. Check with your doctor.

What are the causes of a squint (strabismus)?

Strabismus can be congenital (you are born with it), it can run in families, it can be the result of an illness, long-sightedness, it can also be a sign that a cranial nerve has a lesion. The fact that it can sometimes run in families suggests a genetic link.

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