Diplopia, commonly known as double vision, is the simultaneous perception of two images of a single object that may be displaced horizontally, vertically, or diagonally (i.e. both vertically and horizontally) in relation to each other. It is usually the result of impaired function of the extraocular muscles (EOM's), where both eyes are still functional but they cannot converge to target the desired object. Problems with EOM's may be due to mechanical problems, disorders of the neuromuscular junction, disorders of the cranial nerves (III, IV, and VI) that stimulate the muscles, and occasionally disorders involving the supranuclear oculomotor pathways or ingestion of toxins.
Diplopia is often one of the first signs of a systemic disease, particularly to a muscular or neurological process, and it may disrupt a person’s balance, movement, and/or reading abilities.
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