Amblyopia is sometimes referred to as lazy eye. It can occur because of several problems. For example, if the eyes are not aligned, the brain will favour one eye and ignore the image from the other to avoid double vision. It can also occur if light is not correctly focussed in one eye. The most common cause of light not focussing properly is because of refractive error. Amblyopia develops over time because the brain learns to favour the eye with better vision. Patients who have amblyopia have reduced vision even after vision correction. This is because the signal from the eye to the brain from the amblyopic eye is not as strong as the non-amblyopic eye. The amblyopic eye therefore has all the components to see but the signal is dimmer which in turn makes the vision less vivid. Treatments for amblyopia include glasses or contact lenses, patching and virtual reality vision training. The aim of treatment is to help the brain improve the strength of the signal from the amblyopic eye. Vision training involves temporarily reducing the signal from the good eye to stimulate the amblyopic eye. Results are dependent on the severity of amblyopia, however, in general, vision may improve after 4-6 weeks of daily vision training.