What is diplopia? Diplopia is the medical term for double vision or seeing double. Diplopia is defined as seeing two images of a single object when you're looking at it. Double vision is usually a temporary issue, but it can also be a sign of more serious health conditions. With a careful evaluation and accurate diagnosis, double vision can often be effectively treated. Double vision, also called diplopia, is either monocular or binocular. Monocular double vision is present in each eye separately.