Double Vision Symptoms
Double vision, or "seeing double," occurs when two nonmatching images are sent to the part of the brain that is responsible for processing visual input. If this occurs over the long term, the brain will eventually compensate for the two signals by suppressing one signal, so that a single image is perceived.
What is double vision?
Double vision is the perception of two images of a single object seen adjacent to each other (horizontally, vertically, or obliquely) or overlapping. Double vision is medically termed diplopia. Polyplopia is the perception of three or more images of a single object overlapping each other.
What causes double vision?
There are dozens of causes of double vision ranging from benign to life-threatening. Therefore, it is important for the doctor to carefully review the history and the examination to determine the cause and initiate appropriate treatment when necessary. When one experiences headache and double vision at the same time of more or less simultaneous onset, immediate examination in an emergency room is needed.
What are the symptoms and signs of double vision?
Images may appear to overlap each other or may appear adjacent to each other. Diplopia may vary depending on the direction of gaze or with tilting or turning of the head.
One of the most critical features to determine is whether the diplopia is monocular or binocular. In monocular diplopia, the double vision is caused by a condition within one or both eyes and does not resolve when one eye is covered. In binocular diplopia, the eyes are misaligned. Each eye sees a single image when working alone, as when one eye is covered, but when both eyes are open the brain perceives two adjacent images.
How is the cause of double vision diagnosed?
A thorough evaluation of double vision begins with a detailed history of the diplopia, including onset (gradual or sudden), duration, frequency (intermittent or constant), and variability with head position or eye gaze, noting any associated symptoms (pain, headache, and weight loss among others), and a complete history of past and current medical conditions. The physical examination includes measuring the visual acuity in each eye and assessing whether the diplopia is monocular or binocular. Careful examination of the eyes' alignment in various head positions is performed if the diplopia is binocular. A complete eye examination, which may include dilating the eyes, is performed to look for any ocular or orbital abnormalities. Particular attention is paid to the pupils and eyelid position if a neurologic cause is suspected. In some instances, specialized imaging (topography, MRI, etc.) and other tests are needed to further investigate possible causes. When a life- or vision-threatening cause is suspected, time may be of the essence.
Medically Reviewed by a Doctor on 2/23/2015