What does it mean if I have diplopia?

Double vision. Could mean a number of things, it depends if you are seeing double out of one eye or both eyes together. Sudden onset of diplopia could be serious, so see your eyemd right away. Monocular diplopia often happens as cataracts worsen, and is bothersome, leading to cataract surgery, which usually corrects the problem. Binocular diplopia is an eye muscle and brain problem in most cases.
Two images. Diplopia is the technical term for two images usually one from each eye. It can result from trauma, scarring, orbital pathology, vascular problems, or brain abnormalities. If of recent origin it needs evaluation as soon as possible to eliminate serious pathology.