Diplopia (dip, double; ops, see), or double vision, is seeing the same object in two different places or simply seeing double. The essence of double vision is seeing one clear, or at least clearer, image and a second less-clear image displaced from the first. In most cases, it is fairly easy for the individual with diplopia to recognize the "real thing" when looking at a stationary object in familiar or nonthreatening surroundings. This double vision can be very annoying but can be dealt with by patching or dosing one eye when watching television, reading, or carrying out routine activities in a familiar place. However, when a person is in a more demanding situation (e.g., driving) or around moving objects in an unfamiliar situation, the second image, especially at distance fixation, may produce a great deal of consternation, uncertainty, and even danger. An individual with double vision also loses the more subtle but definite advantage of stereoscopic depth perception when dealing with near objects. From the standpoint of comfortable, effective vision and personal safety, diplopia can play an important role in visual and personal health. Diplopia is usually acquired in visual adulthood and may be caused directly or indirectly by one or more sometimes significant systemic or local conditions.