Disease: Double Vision (Diplopia)

    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.

    What is the treatment for double vision?

    Once the underlying cause has been determined, treatment can be tailored to the underlying cause.

    Most causes of monocular diplopia stem from poor focusing of light by the eye, and treatment is thus aimed at correcting the underlying cause of the blur. For example, refractive errors (myopia, hyperopia, astigmatism) can be corrected with glasses or contact lenses, dry eye with artificial tears and/or tear duct plugs, and cataracts (clouding of the natural lens) with surgery. Other conditions that interfere with proper focusing of light include corneal warping or scars and retinal conditions such as epiretinal membranes. Treatments are tailored to the specific condition believed to be causing the blurred images. Rarely is the underlying cause a medical emergency in cases of monocular diplopia.

    Binocular diplopia on the other hand is produced by a misalignment of the eyes which can be caused by life-threatening conditions. For example, aneurysms, strokes, trauma, and cancers can interfere with the nerves that control the extraocular muscles (the muscles that move the eyes in different direction of gaze, much like the strings on a marionette). Diseases such as myasthenia gravis can interfere with the communication between the nerves and the eye muscles. And the eye muscles themselves can be damaged or compressed by conditions such as thyroid disease, orbital inflammations, vascular disease (as seen with diabetes and high blood pressure), and others. Following traumatic fracture of the orbital bones, muscles and orbital tissue may be trapped in the fracture, leading to misalignment due to restriction of eye movement in certain gaze directions. Sometimes the cause is relatively harmless, such as when the eye muscles or neurologic signals to the muscles weaken with fatigue or illness. Convergence insufficiency, or inability to align the eyes when focusing on a near object, is a common benign cause of intermittent binocular diplopia that can often be treated with glasses with prisms.

    What is the treatment for double vision?

    Once the underlying cause has been determined, treatment can be tailored to the underlying cause.

    Most causes of monocular diplopia stem from poor focusing of light by the eye, and treatment is thus aimed at correcting the underlying cause of the blur. For example, refractive errors (myopia, hyperopia, astigmatism) can be corrected with glasses or contact lenses, dry eye with artificial tears and/or tear duct plugs, and cataracts (clouding of the natural lens) with surgery. Other conditions that interfere with proper focusing of light include corneal warping or scars and retinal conditions such as epiretinal membranes. Treatments are tailored to the specific condition believed to be causing the blurred images. Rarely is the underlying cause a medical emergency in cases of monocular diplopia.

    Binocular diplopia on the other hand is produced by a misalignment of the eyes which can be caused by life-threatening conditions. For example, aneurysms, strokes, trauma, and cancers can interfere with the nerves that control the extraocular muscles (the muscles that move the eyes in different direction of gaze, much like the strings on a marionette). Diseases such as myasthenia gravis can interfere with the communication between the nerves and the eye muscles. And the eye muscles themselves can be damaged or compressed by conditions such as thyroid disease, orbital inflammations, vascular disease (as seen with diabetes and high blood pressure), and others. Following traumatic fracture of the orbital bones, muscles and orbital tissue may be trapped in the fracture, leading to misalignment due to restriction of eye movement in certain gaze directions. Sometimes the cause is relatively harmless, such as when the eye muscles or neurologic signals to the muscles weaken with fatigue or illness. Convergence insufficiency, or inability to align the eyes when focusing on a near object, is a common benign cause of intermittent binocular diplopia that can often be treated with glasses with prisms.

    Source: http://www.rxlist.com

    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.

    Source: http://www.rxlist.com

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