Diplopia
Encyclopedia
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.
or exotropia
. In such a case while the fovea
of one eye is directed at the object of regard, the fovea of the other is directed elsewhere, and the image of the object of regard falls on an extra-foveal area of the retina
.
The brain calculates the 'visual direction' of an object based upon the position of its image relative to the fovea. Images falling on the fovea are seen as being directly ahead, while those falling on retina outside the fovea may be seen as above, below, right or left of straight ahead depending upon the area of retina stimulated. Thus, when the eyes are misaligned, the brain will perceive two images of one target object, as the target object simultaneously stimulates different, non-corresponding, retinal areas in either eye, thus producing double vision.
This correlation of particular areas of the retina in one eye with the same areas in the other is known as retinal correspondence
. This relationship also gives rise to an associated phenomenon of binocular diplopia, although one that is rarely noted by those experiencing diplopia: Because the fovea of one eye corresponds to the fovea of the other, images falling on the two foveas are 'projected' to the same point in space. Thus, when the eyes are misaligned, the brain will 'project' two different images in the same visual direction. This phenomenon is known as 'confusion'.
The brain naturally guards against double vision. In an attempt to avoid double vision, the brain can sometimes ignore the image from one eye; a process known as suppression
. The ability to suppress is to be found particularly in childhood when the brain is still developing. Thus, those with childhood strabismus
almost never complain of diplopia while adults who develop strabismus
almost always do. While this ability to suppress might seem an entirely positive adaptation to strabismus
, in the developing child this can prevent the proper development of vision in the affected eye resulting in amblyopia
. Some adults are also able to suppress their diplopia, but their suppression is rarely as deep or as effective and takes longer to establish, and thus they are not at risk of permanently compromising their vision. Hence, in some cases diplopia disappears without medical intervention, but in other cases the cause of the double vision may still be present.
, a structural defect within the eye, a lesion in the anterior visual cortex
(rarely cause diplopia, more commonly polyopia or palinopsia
) or non-organic conditions.
Also, sub-luxation of the lens.
and Zonisamide
, and the anti-convulsant drug Lamotrigine
, as well as the hypnotic drug Zolpidem
and the dissociative drugs Ketamine
and Dextromethorphan. Temporary diplopia can also be caused by tired and/or strained eye muscles, or by one crossing their own eyes at will. If diplopia appears with other symptoms such as fatigue and acute or chronic pain, the patient should see a doctor immediately.
s possible.
lenses
, and in more extreme situations, surgery or botulinum toxin
.
Perception
Perception is the process of attaining awareness or understanding of the environment by organizing and interpreting sensory information. All perception involves signals in the nervous system, which in turn result from physical stimulation of the sense organs...
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
Extraocular muscles
The extraocular muscles are the six muscles that control the movements of the eye . The actions of the extraocular muscles depend on the position of the eye at the time of muscle contraction.-List of muscles:-Importance:...
(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
Neuromuscular junction
A neuromuscular junction is the synapse or junction of the axon terminal of a motor neuron with the motor end plate, the highly-excitable region of muscle fiber plasma membrane responsible for initiation of action potentials across the muscle's surface, ultimately causing the muscle to contract...
, disorders of the cranial nerves
Cranial nerves
Cranial nerves are nerves that emerge directly from the brain, in contrast to spinal nerves, which emerge from segments of the spinal cord. In humans, there are traditionally twelve pairs of cranial nerves...
(III
Oculomotor nerve
The oculomotor nerve is the 3rd of 12 paired cranial nerves. It enters the orbit via the superior orbital fissure and controls most of the eye's movements, including constriction of the pupil and maintaining an open eyelid by innervating the Levator palpebrae superiors muscle. The optic nerve is...
, IV
Trochlear nerve
The trochlear nerve is a motor nerve that innervates a single muscle: the superior oblique muscle of the eye....
, 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
Systemic disease
Life-threatening disease redirects here.A systemic disease is one that affects a number of organs and tissues, or affects the body as a whole. Although most medical conditions will eventually involve multiple organs in advanced stage Life-threatening disease redirects here.A systemic disease is one...
, particularly to a muscular or neurological process, and it may disrupt a person’s balance, movement, and/or reading abilities.
Binocular
Binocular diplopia is double vision arising as a result of the misalignment of the two eyes relative to each other, such as occurs in esotropiaEsotropia
Esotropia is a form of strabismus, or "squint", in which one or both eyes turns inward. The condition can be constantly present, or occur intermittently, and can give the affected individual a "cross-eyed" appearance...
or exotropia
Exotropia
Exotropia is a form of strabismus where the eyes are deviated outward. It is the opposite of esotropia. People with exotropia often experience crossed diplopia. Intermittent exotropia is a fairly common condition. "Sensory exotropia" occurs in the presence of poor vision...
. In such a case while the fovea
Fovea
The fovea centralis, also generally known as the fovea , is a part of the eye, located in the center of the macula region of the retina....
of one eye is directed at the object of regard, the fovea of the other is directed elsewhere, and the image of the object of regard falls on an extra-foveal area of the retina
Retina
The vertebrate retina is a light-sensitive tissue lining the inner surface of the eye. The optics of the eye create an image of the visual world on the retina, which serves much the same function as the film in a camera. Light striking the retina initiates a cascade of chemical and electrical...
.
The brain calculates the 'visual direction' of an object based upon the position of its image relative to the fovea. Images falling on the fovea are seen as being directly ahead, while those falling on retina outside the fovea may be seen as above, below, right or left of straight ahead depending upon the area of retina stimulated. Thus, when the eyes are misaligned, the brain will perceive two images of one target object, as the target object simultaneously stimulates different, non-corresponding, retinal areas in either eye, thus producing double vision.
This correlation of particular areas of the retina in one eye with the same areas in the other is known as retinal correspondence
Retinal correspondence
Retinal correspondence is the inherent relationship between paired retinal visual cells in the two eyes. Images from one object stimulate both cells, which transmit the information to the brain, permitting a single visual impression localized in the same direction in space.-Types:Normal retinal...
. This relationship also gives rise to an associated phenomenon of binocular diplopia, although one that is rarely noted by those experiencing diplopia: Because the fovea of one eye corresponds to the fovea of the other, images falling on the two foveas are 'projected' to the same point in space. Thus, when the eyes are misaligned, the brain will 'project' two different images in the same visual direction. This phenomenon is known as 'confusion'.
The brain naturally guards against double vision. In an attempt to avoid double vision, the brain can sometimes ignore the image from one eye; a process known as suppression
Suppression (eye)
Suppression of an eye is a subconscious adaptation by a person's brain to eliminate the symptoms of disorders of binocular vision such as strabismus, convergence insufficiency and aniseikonia. The brain can eliminate double vision by ignoring the images of one of the eyes...
. The ability to suppress is to be found particularly in childhood when the brain is still developing. Thus, those with childhood strabismus
Strabismus
Strabismus is a condition in which the eyes are not properly aligned with each other. It typically involves a lack of coordination between the extraocular muscles, which prevents bringing the gaze of each eye to the same point in space and preventing proper binocular vision, which may adversely...
almost never complain of diplopia while adults who develop strabismus
Strabismus
Strabismus is a condition in which the eyes are not properly aligned with each other. It typically involves a lack of coordination between the extraocular muscles, which prevents bringing the gaze of each eye to the same point in space and preventing proper binocular vision, which may adversely...
almost always do. While this ability to suppress might seem an entirely positive adaptation to strabismus
Strabismus
Strabismus is a condition in which the eyes are not properly aligned with each other. It typically involves a lack of coordination between the extraocular muscles, which prevents bringing the gaze of each eye to the same point in space and preventing proper binocular vision, which may adversely...
, in the developing child this can prevent the proper development of vision in the affected eye resulting in amblyopia
Amblyopia
Amblyopia, also known as lazy eye, is a disorder of the visual system that is characterized by a vision deficiency in an eye that is otherwise physically normal, or out of proportion to associated structural abnormalities of the eye...
. Some adults are also able to suppress their diplopia, but their suppression is rarely as deep or as effective and takes longer to establish, and thus they are not at risk of permanently compromising their vision. Hence, in some cases diplopia disappears without medical intervention, but in other cases the cause of the double vision may still be present.
Monocular
More rarely, diplopia can also occur when viewing with only one eye; this is called monocular diplopia, or, where the patient perceives more than two images, monocular polyopia. In this case, the differential diagnosis of multiple image perception includes the consideration of such conditions as corneal surface keratoconusKeratoconus
Keratoconus , is a degenerative disorder of the eye in which structural changes within the cornea cause it to thin and change to a more conical shape than its normal gradual curve....
, a structural defect within the eye, a lesion in the anterior visual cortex
Visual cortex
The visual cortex of the brain is the part of the cerebral cortex responsible for processing visual information. It is located in the occipital lobe, in the back of the brain....
(rarely cause diplopia, more commonly polyopia or palinopsia
Palinopsia
Palinopsia is a visual disturbance that causes images to persist to some extent even after their corresponding stimulus has left. These images are known as afterimages and occur in persons with normal vision...
) or non-organic conditions.
Also, sub-luxation of the lens.
Temporary
Temporary diplopia can be caused by alcohol intoxication or head injuries, such as concussion. If temporary double vision does not resolve quickly, one should see an ophthalmologist immediately. It can also be a side effect of the anti-epileptic drugs PhenytoinPhenytoin
Phenytoin sodium is a commonly used antiepileptic. Phenytoin acts to suppress the abnormal brain activity seen in seizure by reducing electrical conductance among brain cells by stabilizing the inactive state of voltage-gated sodium channels...
and Zonisamide
Zonisamide
Zonisamide is a sulfonamide anticonvulsant approved for use as an adjunctive therapy in adults with partial-onset seizures for adults; infantile spasm, mixed seizure types of Lennox-Gastaut syndrome, myoclonic, and generalized tonic clonic seizure.-History:...
, and the anti-convulsant drug Lamotrigine
Lamotrigine
Lamotrigine, marketed in the US and most of Europe as Lamictal by GlaxoSmithKline, is an anticonvulsant drug used in the treatment of epilepsy and bipolar disorder. It is also used as an adjunct in treating depression, though this is considered off-label usage...
, as well as the hypnotic drug Zolpidem
Zolpidem
Zolpidem is a prescription medication used for the short-term treatment of insomnia, as well as some brain disorders. It is a short-acting nonbenzodiazepine hypnotic of the imidazopyridine class that potentiates gamma-aminobutyric acid , an inhibitory neurotransmitter, by binding to GABAA...
and the dissociative drugs Ketamine
Ketamine
Ketamine is a drug used in human and veterinary medicine. Its hydrochloride salt is sold as Ketanest, Ketaset, and Ketalar. Pharmacologically, ketamine is classified as an NMDA receptor antagonist...
and Dextromethorphan. Temporary diplopia can also be caused by tired and/or strained eye muscles, or by one crossing their own eyes at will. If diplopia appears with other symptoms such as fatigue and acute or chronic pain, the patient should see a doctor immediately.
Voluntary
Some people are able to consciously uncouple their eyes, inducing double vision on purpose. These people do not consider their double vision dangerous or harmful, and may even consider it enjoyable. It makes viewing stereogramStereogram
A stereogram is pair of two-dimensional panels depicting the view of a scene or an object from the vantage points of the right and left eyes. Observing the panels superimposed in a stereoscope results in the experience of three-dimensionality by virtue of the fact that object depth is encoded as...
s possible.
Causes
Diplopia has a diverse range of ophthalmologic, infectious, autoimmune, neurological, and neoplastic causes.- Damage to the thirdOculomotor nerveThe oculomotor nerve is the 3rd of 12 paired cranial nerves. It enters the orbit via the superior orbital fissure and controls most of the eye's movements, including constriction of the pupil and maintaining an open eyelid by innervating the Levator palpebrae superiors muscle. The optic nerve is...
, fourthTrochlear nerveThe trochlear nerve is a motor nerve that innervates a single muscle: the superior oblique muscle of the eye....
, or sixth cranial nerves, which control eye movements. - CancerCancerCancer , known medically as a malignant neoplasm, is a large group of different diseases, all involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumors, and invade nearby parts of the body. The cancer may also spread to more distant parts of the...
- TraumaPhysical traumaTrauma refers to "a body wound or shock produced by sudden physical injury, as from violence or accident." It can also be described as "a physical wound or injury, such as a fracture or blow." Major trauma can result in secondary complications such as circulatory shock, respiratory failure and death...
- Multiple sclerosisMultiple sclerosisMultiple sclerosis is an inflammatory disease in which the fatty myelin sheaths around the axons of the brain and spinal cord are damaged, leading to demyelination and scarring as well as a broad spectrum of signs and symptoms...
- BotulismBotulismBotulism also known as botulinus intoxication is a rare but serious paralytic illness caused by botulinum toxin which is metabolic waste produced under anaerobic conditions by the bacterium Clostridium botulinum, and affecting a wide range of mammals, birds and fish...
- Guillain-Barré syndromeGuillain-Barré syndromeGuillain–Barré syndrome , sometimes called Landry's paralysis, is an acute inflammatory demyelinating polyneuropathy , a disorder affecting the peripheral nervous system. Ascending paralysis, weakness beginning in the feet and hands and migrating towards the trunk, is the most typical symptom...
- Brain tumorBrain tumorA brain tumor is an intracranial solid neoplasm, a tumor within the brain or the central spinal canal.Brain tumors include all tumors inside the cranium or in the central spinal canal...
- SinusitisSinusitisSinusitis is inflammation of the paranasal sinuses, which may be due to infection, allergy, or autoimmune issues. Most cases are due to a viral infection and resolve over the course of 10 days...
- AbscessAbscessAn abscess is a collection of pus that has accumulated in a cavity formed by the tissue in which the pus resides due to an infectious process or other foreign materials...
- Wernicke's syndromeWernicke's encephalopathyWernicke encephalopathy is a syndrome characterised by ataxia, ophthalmoplegia, confusion, and impairment of short-term memory.It is caused by lesions in the medial thalamic nuclei, mammillary bodies, periaqueductal and periventricular brainstem nuclei, and superior cerebellar vermis, often...
- Graves disease
- DrunkennessDrunkennessAlcohol intoxication is a physiological state that occurs when a person has a high level of ethanol in his or her blood....
- Orbital myositis
- Myasthenia gravisMyasthenia gravisMyasthenia gravis is an autoimmune neuromuscular disease leading to fluctuating muscle weakness and fatiguability...
- AnisometropiaAnisometropiaAnisometropia is the condition in which the two eyes have unequal refractive power; that is, are in different states of myopia , hyperopia or in the extreme, antimetropia , the unequal refractive states cause unequal rotations thus leading to diplopia and asthenopia.Anisometropia can adversely...
- Salicylism
- StrabismusStrabismusStrabismus is a condition in which the eyes are not properly aligned with each other. It typically involves a lack of coordination between the extraocular muscles, which prevents bringing the gaze of each eye to the same point in space and preventing proper binocular vision, which may adversely...
- Lyme's Disease
Treatment
The appropriate treatment for binocular diplopia will depend upon the cause of the condition producing the symptoms. Efforts must first be made to identify and treat the underlying cause of the problem. Treatment options include eye exercises, wearing an eye patch on alternative eyes, prismPrism (optics)
In optics, a prism is a transparent optical element with flat, polished surfaces that refract light. The exact angles between the surfaces depend on the application. The traditional geometrical shape is that of a triangular prism with a triangular base and rectangular sides, and in colloquial use...
lenses
Lens (optics)
A lens is an optical device with perfect or approximate axial symmetry which transmits and refracts light, converging or diverging the beam. A simple lens consists of a single optical element...
, and in more extreme situations, surgery or botulinum toxin
Botulinum toxin
Botulinum toxin is a protein produced by the bacterium Clostridium botulinum, and is considered the most powerful neurotoxin ever discovered. Botulinum toxin causes Botulism poisoning, a serious and life-threatening illness in humans and animals...
.
External links
- Common Cause of Double Vision
- All About Double Vision
- International Orthoptic Association
- All About Lazy Eye
- FAQ -- Eye Muscle Surgery Information
- Brain Injuries and Double Vision
- Some more info about diplopia
- Addtl info about diplopia
- What is Stereovision?
- What is Vision Therapy?
- VisionSimulations.com | What the world looks like to people with various diseases and conditions of the eye
- GPnotebook