Q: I was born with eyes that squint and am considering corrective surgery. Is this considered a cosmetic procedure? What are the risks, side effects and chances of recovery?

A: A squint (the medical term being 'strabismus') is a misalignment of one or both eyes. It can occur with the eyes deviating inwards or outwards.

Surgery is often recommended when the squint is constant or significant, affects the person's vision or if there is an abnormal head position.

Binocular vision, described as the use of both eyes to perceive three-dimensional images and depth, develops at a young age.

However, a constant squint from young prevents this binocular function from fully developing. A lazy eye may result, which is why surgery is recommended at a young age to preserve or restore binocular vision.

Squint surgery later in life can realign the eyes but does not improve binocular vision.

Before performing surgery, doctors will first have to correct any refractive error. Squint surgery corrects the misalignment of the eyes through muscle strengthening, weakening or realignment procedures.

Adult squint surgery may be done using adjustable stitches so that the surgeon can fine-tune the position of the eyes after the operation. This is done while the patient is awake.

Although the eyes may be successfully realigned with one surgery, further surgery may be required to improve the result.

Even if no improvement in visual function results, squint surgery is not a cosmetic procedure.

Like any other form of surgery, it carries some risks, but in the hands of an experienced surgeon, it is generally very safe. Serious complications are rare. If a doctor has recommended surgery for a patient, it would be because the benefits far outweigh the small potential risks.

People who have had a squint since childhood or who have poor vision in one eye will usually not have three-dimensional vision. This means that even when their eyes have been aligned through surgery, they will still lack the ability to use their eyes together.

It is also possible that their eyes will drift inwards or outwards again.

DR LEONARD ANG

Medical director of The Eye And Cornea Transplant Centre and the Premium Lasik Surgery Clinic

This article was first published in Mind Your Body, The Straits Times.