The causes of double vision or diplopia are very diverse, since many factors and associated diseases are involved. The diplopia is a visual disturbance that occurs when a person sees two images of the same object. It is not a disease, but a symptom that is related to various eye and systemic conditions. 

When we close and open our eyes, both organs look at the same place to make it possible for the brain to process the vision of each eye as a single image and thus be able to have a more real perception of depth.

However, for this to be possible, many parts of the visual system intervene, and if any of the parties involved fail, it is possible that diplopia is present, a condition that is characterized by having the person visualize two images of the same object. .

The causes of diplopia are diverse. Many times this discomfort can be caused by a minor problem such as a refractive defect. It can also happen that double vision is generated by defects in the cornea, problems in the retina or neurological conditions. 

En Área Oftalmológica Avanzada We explain the causes of double vision or diplopia.

causes of double vision or diplopia

Types of diplopia

Diplopia is a disorder that causes double vision of images. This condition can manifest itself in a monocular or binocular way. In both cases, it can be: 

  • Horizontal: The overlapping images are next to each other. 
  • Vertical: The overlaid images are one on top of the other. 
  • Oblique: Images are seen overlapping in a diagonal direction. 

Monocular diplopia

La monocular diplopia is the one that affects and causes double vision in one eyeThat is, if we suppose that a person has double vision in the right eye, it disappears when this eye is closed and only the left one is open. When a patient presents this type of alteration, double vision disappears when the affected eye is covered and persists when the healthy eye is covered. In these cases, the double image does not disappear when looking in different directions. 

Monocular diplopia is more common than binocular diplopia and is associated with benign conditions such as the syndrome of Dry Eye, Cataracts, problems in the crystalline, graduation problems and alterations in the retina and cornea. People with this diplopia see an image superimposed on the main image.

Binocular diplopia

La binocular diplopia is much more complex, since affects both eyes at the same time. This type of double vision is usually caused by a problem in the alignment of the visual axes that completely out of square the image perceived by each eye, causing double vision of objects.

Unlike monocular double vision, in binocular the 2 images that are observed are not blurred or superimposed, but you can easily differentiate one from the other and see the space between them. Double vision disappears when one of the two visual structures is occluded.  

This type of double vision is usually associated with squint, problems in some nerves, muscular diseases, thyroid malfunction or alterations in the central nervous system.

diplopia causes

Causes of diplopia

Opening the eyes and observing a single image may seem simple and normal, however, for this to happen, a series of components such as the cornea, the lens, the inner muscles of the eye, those around the eye and those that hold it are involved , the brain and the optic nerve. Therefore, any disorder or condition that gets in the way of any of the parts mentioned above can be a cause of double vision.

  • problems with the corneaThey usually cause monocular double vision and occurs due to an uneven corneal surface that allows light entering the eye to be distorted. Dry eye is the most common cause of monocular diplopia due to problems in the cornea, followed by viruses, herpes, scars, infections and the keratectasia, which is the progressive deformation or weakening of the cornea.
  • Muscle problems: the muscles must hold the eye correctly so that it does not move and does not compromise the alignment of the vision. However, some conditions of the neurological system can cause muscle weakness that causes a binocular diplopia.
  • Problems in the lens: When diplopia is caused by a lens condition, it usually affects both eyes at the same time and is mostly associated with the formation of cataracts. Remember that monocular diplopia can sometimes be present in both eyes at the same time.
  • optic nerve problems: diseases like diabetes and multiple sclerosis they can cause progressive deterioration in the nerves of the body, affecting the optic nerve and resulting in a usually binocular diplopia.
  • Brain problemsAlthough less frequently, some neurological conditions can also be responsible for double vision. The brain is responsible for controlling the nerves and processing the visual image that the eyes observe, therefore, conditions associated with this organ such as aneurysms, strokes, tumors, cerebral hypertension and migraine can cause double vision.

Causes of monocular diplopia

Monocular diplopia is the type of double vision that is most related to problems or defects in the ocular structure. Their main causes are: 

  • Astigmatism: it is a refractive defect that is characterized by causing distorted or blurred vision at any distance. Astigmatism can be corrected through the use of glasses, contact lenses or through refractive surgery. It can cause diplopia due to the abnormal curvature of the corneal surface. 
  • Keratoconus: This disease occurs when the cornea progressively thins and takes on a shape similar to that of an American football. Keratoconus can affect both eye structures at the same time. 
  • Cataract: The lens of the eye is the natural lens of the visual system. Over the years, it loses its transparency and cataracts can form on its surface. This abnormality is one of the main causes of blurred and limited vision in the elderly. To treat this condition, it is advisable to remove the lens and replace it with an intraocular lens. 
  • Pterygium: this alteration occurs when the thickening of the conjunctiva, the thin, transparent membrane that lines the white of the eye. Pterygium can spread to the cornea and cause unfortunate vision consequences. 
  • retinal diseases: can cause double vision or monocular diplopia. 

Causes of binocular diplopia

Binocular diplopia is almost always caused by problems in extrinsic muscles Of the eye and diseases of the nervous system, brain, and other parts of the body. The causes of binocular diplopia are: 

  • Squint: is the deviation of the visual axes that most frequently affects children under 6 years of age. Strabismus can occur due to some problem during the development of the fetus or due to the malfunction of the extrinsic muscles of the eye. It can be treated in different ways and, among the most common, we find the use of glasses, prisms, visual therapy and strabismus surgery. The operation aims to strengthen or weaken the muscles of the eye to correct the deviation of the eyeball. 
  • Nerve damage- Binocular diplopia can also occur when the nerves that control the muscles of the eye do not work properly. This happens due to a brain infection, stroke, multiple sclerosis, head trauma or brain tumors among others. 
  • Diseases such as myasthenia gravis and diabetes They can also alter the function of the nerves that control the muscles of the eye. 
  • Graves disease: This condition is the most common cause of hyperthyroidism. Remember that this disease occurs when the thyroid gland produces an excessive amount of thyroid hormone. Some people with this condition have double vision, due to the thickening of the extrinsic muscles of the ocular structure. 
  • Trauma: any blow that hits the eye strongly and directly can trigger inflammatory processes, bleeding and injury to the eye orbit
causes double vision


The diplopia is manifested mainly with the symptom of double vision and every person who experiences this discomfort should immediately attend the ophthalmologist to make a complete evaluation of both eyes and be able to determine what is the cause of the double vision. In order to diagnose double vision or diplopia, the medical specialist must:

  • Assess the ability of each eye to perform coordinated movements and thus rule out or check the existence of a muscle that is not working properly, either because of paralysis or due to overstrain.
  • Perform tests to measure gaze position, known as evidence of orthoptics.
  • Request the person to carry out additional tests to rule out any other conditions that does not originate in the visual area. Among the tests that are usually requested is a general analysis, hormonal analysis to rule out thyroid problems, infections or autoimmune diseases, resonance or tomography brain and electromyogram.

Treatment of diplopia

El double vision treatment It depends a lot on its cause, since many times the problem does not appear in the eye, but in another part of the body. However, to correct double vision disorder, the use of premium glasses is often used to realign the vision and produce a single image. It is also possible to treat double vision through surgery when the cause is conditions such as astigmatism, cataracts or strabismus.

In the case of infections, it will be necessary to start treatment with antibiotic drugs to fight bacteria. Diseases of the muscular system, the thyroid and the circulatory system should also be treated immediately with the pertinent medications according to each case.

Double vision of the images is a symptom that must be attended to immediately by an ophthalmologist. Because diplopia can be caused by various diseases, it will be necessary make a comprehensive eye exam to detect its cause

En Área Oftalmológica Avanzada We are here to help you. We have a amplio team of professional ophthalmologists who will help you determine the causes of double vision and the best way to treat this condition.

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Causes of diplopia or double vision
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Causes of diplopia or double vision
The causes of double vision can be varied and are usually related to eye problems. In this article we explain them in detail.
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Área Oftalmológica Avanzada
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