Amblyopia, also known as lazy eye, is a condition in which vision in one eye is very much worse than in the other.

The two 'views' provided by the eyes cannot be combined into one '3-D' image by the brain, so the patient loses their 'binocular' vision (binocular vision is where the combination of the images from the two eyes enables the person to see in 3-D).

To find out more about lazy eyes, see our dedicated guide.