Double vision, or diplopia, arises from problems with the cornea, or the eye's window, the lens, eye muscles, the visual nerve or the brain's visual system. Double vision can be horizontal, where a picture from one eye is doubled, or vertical, where a picture from one eye lies on top of a picture of the other eye. Though double vision usually is a sign of a serious problem in the visual system, it can also occur with the use of depressant medications, such as alcohol and benzodiazepines. This class of substances causes a retardation of the neurological system, which may result in disturbances in the eye's ability to focus.
Infections of the Cornea
The herpes simplex virus HSV1 or HSV2 and the chickenpox virus can infect the cornea of one or both eyes. When the cornea is infected, the light reaching the eyes gets distorted, which can lead to double vision. Contact lens solutions are another common source of corneal infections, according to a study published in the January 2008 issue of "Antimicrobial Agents and Chemotherapy." Improper care of contact lenses or the use of an ineffective lens solution can result in the formation of clusters of fungus held together in a glue-like grid. Once these so-called biofilms have formed, the microorganisms constituting them are resistant to both the body's own immune system and contact lens solutions, the researchers found.
Cataracts
A cataract is a common eye disease that involves a clouding of the eye's lens. Double vision can occur when a cataract is present in one eye but occurs more frequently when both eyes are affected. There is a significant correlation between cataracts and common serotonin reuptake inhibitors, according to a study published in the June 2010 issue of "Ophthalmology." Just like the brain, the eye's lens has serotonin receptors. Serotonin reuptake inhibitors increase serotonin levels in the brain. This excess serotonin may bind to the receptors in the lens, causing opaqueness of the lens, the researchers say.
Grave's Disease
Grave's disease is a complication of a hyperactive thyroid, an autoimmune condition. It causes the eye's muscles to weaken and results in a bulging appearance of the eyes. Grave's disease occurs when an immune system cell type called fibrocytes attacks the eye's muscles, reports a University of Michigan research team in the January 2010 issue of "Journal of Clinical Endocrinology & Metabolism." It has been known for some time that fibrocytes can cause scarring in lungs, but the Michigan study is the first to associate fibrocytes with hyperthyroidism. When scarring occurs, Grave's disease can result in so-called vertical diplopia, in which the image from one eye lies on top of the image from the other eye.
Multiple Sclerosis
Multiple sclerosis, or MS, is an autoimmune disease in which the immune system attacks the neurological system in the brain or spinal cord. If the immune system attacks the optical nerve, double vision may occur. MS can also cause a thinning of the retina, which can lead to blurry vision and double vision. This common effect of MS can be used as an early diagnostic, reports a University of Texas Southwestern research team in the June 2010 issue of "Annals of Neurology." The researchers found that a method called optical coherence tomography can detect an early thinning of the retina in patients with MS before other symptoms develop.
Brain Dysfunction
Brain dysfunction resulting from migraine headache, a brain tumor, a head trauma, a stroke or brain aneurysms can result in double vision. An aneurysm is a bulging of a blood vessel due to a weakening of the vessel's wall. It can occur as a result of head injury or a stroke. An untreated brain aneurysm can lead to a deadly rupture, reports the Mayo Clinic in Science Daily. In collaboration with radiologists, the Mayo Clinic has developed a new digital imagining technique that can reliably detect brain aneurysms at an early stage. The initial data from this new collaborative project was published online on November 24, 2010, in "Journal of Digital Imaging."
References
- "Antimicrobial Agents and Chemotherapy"; Fusarium and Candida albicans Biofilms on Soft Contact Lenses: Model Development, Influence of Lens Type, and Susceptibility to Lens Care Solutions; Imamura, et al.; January 2008
- "Ophthalmology"; Selective Serotonin Reuptake Inhibitors and the Risk of CataractsA Nested Case-Control Study; Etminan, et al.; June 2010
- "Journal of Clinical Endocrinology & Metabolism"; Increased Generation of Fibrocytes in Thyroid-Associated Ophthalmopathy; Douglas, et al.; January 2010
- "Annals of Neurology"; Longitudinal study of vision and retinal nerve fiber layer thickness in MS; Talman, et al.; June 2010
- Science Daily: Early Detection of Brain Aneurysms Is Aim of Advanced Computing Project
