Squint ("Eye Misalignment")

What is a squint?

A squint, medically termed "strabismus", is a condition of misaligned eyes. One or sometimes both of the eyes may turn inwards, outwards, or less commonly upwards or downwards.

OUTWARD DEVIATION

UPWARD DEVIATION

The misalignment can be constant, meaning the same eye deviates in a certain direction all the time, or intermittent, meaning the misalignment occurs only at certain times, often when the afflicted person is tired, sick or daydreaming.

Why do squints occur?

Most squints are the result of abnormal neuromuscular control of eye movements. This is unfortunately not well understood.

Occasionally, squints can result from conditions affecting the eye muscles such as fractures of the eye socket, or in certain brain conditions which affect nerves supplying the eye muscles.

What are the symptoms of a squint?

Besides the noticeable eye misalignment, squints can also cause double vision ("diplopia"), lazy eye ("amblyopia") in young children, or even development of abnormal head postures like a face turn or head tilt.

Squint and lazy eye differentiated

There is a common misconception that squint and lazy eye are the same condition. Lazy eye, medically termed "amblyopia" is a decrease in a child's vision that results when one or both eyes send a blurry image to the brain. The brain then "learns" to see blurry with the affected eye/eyes, even when appropriate glasses are given. Lazy eye can occur even though there are no structural problems within the eye. There are several causes of lazy eye and squint is one of them. Hence, these two conditions are related but commonly wrongly mistaken to be the same condition.

How do squints affect three-dimensional (3D) vision?

Three dimensional vision is the ability to perceive depth. In order to experience good depth perception, we require decent vision in both eyes and to have both eyes aligned.

Development of depth perception occurs during the critical period from after birth till ages 4-5. However, it does not mean that if the critical period for depth perception to develop has passed, no treatment for squint should be rendered. Age should not be a deterrent to treatment, though treatment prior to age 6 could allow for better results compared with later treatment.

When to seek help

If friends or relatives notice the eye misalignment
A squint is suspected during eye screening by your family physician or paediatrician

What are the risk factors for developing a squint?

Family history of squints
Uncorrected long-sightedness (hyperopia) or short-sightedness (myopia)
Premature birth
Significant vision impairment from any cause

What are my treatment options?

Most squints in children need to be assessed as soon as possible to prevent the onset of lazy eye and to improve the chances of successful treatment.

If the child already has lazy eye, an eye patch may be required over the normal eye to encourage use of the squinting lazy eye.

Depending on the type of squint, treatments options include glasses, eye exercises when appropriate, and occasionally surgery or Neuromodulators to selected muscles.

When would an eye doctor recommend surgery for my squint?

Squint surgery is recommended if squint control is poor, the squint occurs all the time, 3D depth perception is deteriorating, or to permanently correct a persistent abnormal head posture.

When is a "good" age to undergo squint surgery?

Parents of a child with a squint often ask if their child is too young to undergo squint surgery. Patients who undergo this procedure can be as young as 6 months of age, and even above 80 years of age.

For the children, squint surgery gives them a chance to regain a normal eye alignment thereby facilitating the development of some amount of depth perception, or corrects an abnormal head posture.

Similarly, adults often ask if it's too late for anything to be done, many having lived with their condition for years. Corrective squint surgery is often undertaken to correct double vision, and to regain normal eye alignment, even though depth perception may not be regained.

Is squint surgery a cosmetic procedure?

Definitely not! Squint surgery is reconstructive, and restores eyes back to normal alignment. The subtler benefit is a positive impact on patients' psychological well-being. Many scientific studies have demonstrated that people with squints are discriminated against during recruitment interviews, passed over for promotion and are less likely to find a partner. In some people the loss of confidence and self-esteem can be very debilitating, and this is especially true if their job involves regular face-to-face encounters with different people.

How is squint surgery performed?

Squint surgery involves tightening, relaxing or re-positioning the external eye muscles, to alter the eye position.
 

EXTERNAL EYE MUSCLES

This is nearly always a day-case procedure, and can be performed adjustable or non-adjustable. In adjustable squint surgery, which can be performed in cooperative older children and adults, the stitches can be adjusted shortly after the surgery, when the patient is awake, to fine-tune the post-operative eye alignment.

Read more about Squints.