Authored by MCN Neurologists
Causes of Diplopia
Diplopia refers to double vision. Diplopia can result from problems affecting the brain (brainstem), the nerves that control the eye muscles, the neuromuscular junction (the connection between the nerve and the muscle) or conditions that affect the eye muscles themselves.
The most common origin seems to be problems with the three nerves that control the six muscles that move the eyes within their sockets. The nerves are “yoked” within the brainstem and normal vision depends on each eye looking at exactly the same point. If they move incorrectly, such that they are aimed at two different sites, double vision occurs.
Diabetes, Guillain-Barre Syndrome (French polio) and immune neuropathies commonly cause diplopia. Myasthenia Gravis, hyperthyroidism and other muscle diseases can create the same symptoms. The most feared cause of diplopia is an unruptured, thus unsuspected, aneurysm pressing on one of the nerves to the eye. In addition, tumors are routinely suspected.
Diagnosis of Diplopia
The evaluation for a cause of double vision is usually performed by a neurologist or eye specialist (ophthalmologist or neuro-ophthalmologist). A careful history and examination often will provide important clues as to the likely diagnosis. Lab tests may be ordered to look for conditions, such as diabetes, thyroid disorder or myasthenia gravis. Imaging of the brain and brainstem with an MRI scan is often an important test in the evaluation of diplopia.
Treatment of Diplopia
The most effective treatment for double vision is to try to identify the cause and treat that cause directly. For example, this would apply to conditions such as thyroid disorders or myasthenia gravis. In some situations, the cause may not be found, or the condition may not be treatable. In those situations, strategies, such as the use of prisms in eyeglasses, can be useful.