Binocular single vision

BSV is the ability to use both eyes to create a single, common perception. It can be broken down into three component parts:

• simultaneous perception - with each eye seeing the image at the same time
• fusion - where the images from each eye are fused to give a single image at the visual cortex
• stereopsis - where fusion of the slightly different images from each eye are interpreted to allow a perception of depth

Note that BSV breaks down if there is a difference in image sizes of 8% or more, which may be caused by, for example, spectacle lenses that are 3 - 4 dioptres different.