Diplopia, commonly known as double vision, occurs when a person sees two images of a single object. This condition can result from various issues, including problems with the eye muscles, nerves, or the brain. It can affect one eye (monocular diplopia) or both eyes (binocular diplopia), and the images may be aligned or misaligned. The causes of diplopia can range from eye strain and fatigue to more serious conditions like thyroid eye disease or multiple sclerosis. Treatment options depend on the underlying cause and may include corrective lenses, eye exercises, or surgery.