Strabismus: Definition, Symptoms, Causes, Types and Treatment

If you notice that your child appears to have narrowed eyes after six weeks of age, you should have his eyes examined as soon as possible by an optometrist.

Strabismus is a condition that occurs due to improper balance of the muscles that move the eye, faulty nerve signals to the muscles of the eye, and failure to focus (usually on sight).

If they are out of balance, the eye can turn, or sometimes go up or down, preventing the eyes from working properly together.

Strabismus can occur at any age. A baby can be born with a squint or develop one shortly after birth.

About five to eight percent of children are affected by a strabismus or a condition related to strabismus, which means one or two in every group of 30 children.

Many children with narrowed eyes have poor vision in the affected eye. If treatment is needed, the earlier it is started, the better the results.


  • Normally, the two eyes point in the same direction.
  • A “strabismus” occurs when the two eyes are misaligned.
  • This can happen in either eye and the misalignment can be in any direction.
  • A strabismus can occur for a number of reasons.
  • Sometimes one or more of the muscles that move the eyes are in the wrong place.
  • Sometimes the muscles don’t work the way they should.
  • A long-standing strabismus does not usually affect vision
  • A recent squint can result in double vision and should be fully investigated.

Causes and types of strabismus

There are several types of strabismus. The causes are not always known, but some children are more likely to develop it than others. Possible causes include:

Congenital strabismus

Sometimes a baby is born with a squint, although it may not be obvious for a few weeks.

In about half of these cases, there is a family history of strabismus or the need for glasses. The eye muscles are often to blame.

If strabismus is suspected, it is important to refer the baby for an accurate evaluation as soon as possible.

Sometimes a baby has what is known as “pseudo squint,” which is related to the shape of the face.

Prolonged vision (farsightedness)

Farsightedness can sometimes lead to a strabismus that develops as the eyes become “too focused” to see clearly.

In an attempt to avoid double vision, the brain may automatically respond by turning off the image of one eye and rotating the eye to avoid using it.

If left untreated, it can lead to a “lazy eye” (amblyopia). The most common age for this type of strabismus to begin is between 10 months and 2 years, but it can occur up to 5 years.

It is usually first noticed when a baby is looking at a toy, or at a later age when a child is concentrating on close work, such as a puzzle or reading.

Childhood diseases

Strabismus can occur after an illness such as measles or chickenpox.

This may mean that there has been a tendency to squint but, before the illness, the child was able to keep his gaze straight.

Nerve damage

In some cases, a difficult delivery of a baby or a disease that damages a nerve can lead to strabismus.

How can I tell if my child has a squint?

People often think that they can tell if a child has squinted eyes if the eyes look unusual or if the two eyes look different.

This is not necessarily a squint.

Symptoms of strabismus are often difficult to detect, especially in younger children. Older children may complain of vision problems, such as double vision.

If a child is suspected of having squinted eyes, ask your health visitor, children’s health clinic, about a referral to an optometrist, ophthalmologist, or eye clinic for evaluation.

Isn’t a squint just a cosmetic problem?

Certainly appearance can cause problems for the child, but a squint is not simply a cosmetic problem.

If left untreated, you can cause a permanent visual defect in the eye by squinting.

Treating strabismus would be cosmetically desirable, and glasses or surgery can work well in many cases.


Treatment of strabismus varies depending on the type of strabismus. An operation is not always necessary. The main forms of treatment are:

  • Glasses: to correct any vision problems, especially in the long term.
  • Occlusion: patching the good eye to encourage use of the weaker eye. This is usually done under the supervision of an orthoptist.
  • Eye drops: Certain types of strabismus can be treated with the use of special eye drops.
  • Surgery – Used for congenital strabismus, along with other forms of treatment in older children, if needed. Surgery can be done as early as a few months of age.