Strabismus, commonly known as a squint, occurs in 2 - 4 percent of the population, and is most commonly noticed in young children. This condition occurs when the muscles which move the eyes (the extra-ocular muscles) do not work together properly, and there may be a misalignment of the eyes (one eye is at an angle when the person looks straight ahead) or a lack of co-ordination. As the eyes point in slightly different directions, the brain cannot combine the views from each eye to produce a sharp 3-D image. Two common types of squint are inward turning of one or both eyes (convergent squint or crossed-eyes) and outward turning of one or both eyes (divergent squint or 'walleye'). If you are worried that your child may have a squint, then seek advice from a qualified optician or your medical practitioner.