Monocular vision is using each eye separately, binocular vision is using both eyes. Some people mistake monocular vision for mono-focal. I am going out on a limb and assuming that this is what you are actually asking about, if not I apologize in advance. Mono-focal is when the eye for some reason does not accommodate for different distances. Most often this happens when people have the lens in their eye replaced. There are basically 2 replacement lens types, mono-focal and multifocal. The better of the 2 of course is the multifocal because the lens actually changes shape to focus on objects just like the lens that was removed once did, the mono-focal however, is rigid and does not change so corrective lenses are still necessary. Hope this helps, Susanne