As the condition suggests, double vision is seeing overlapping (one on top of other) or adjacent (horizontal) or oblique images of a single object. The medical terminology for double vision is diplopia.It occurs due to loss of function of the extraocular muscles (EOMs). In this case, the eyes continue to function, that is see, but are unable to converge to target a specific object.Sometimes, the underlying cause may not be serious but other times it could be life threatening.Let’s figure out the symptoms, causes, diagnosis, and treatment options for double vision.
Signs and symptoms of double vision
Depending on the nature of double vision, it’s classified into three categories:
Binocular double vision: Both eyes do not co-ordinate properly, so double vision occurs in both eyes. However the object might be perceived normally when seen with one eye, keeping the other covered.
Monocular double vision: The defect lies in one eye. The objects appear clear when seen with the normal eye while covering the defective eye. Sometimes, two images are seen as slightly separated, which is known as ghosting.
Physiological double vision- The objects (in the background) which are not primarily in your focus appear to be overlapping. This is more common in children.
Double vision may differ depending on the direction of view and the position of the head.
What causes double vision?
The mechanism behind the double vision is: the eyes fail to focus in the same direction due to incorrect coordination between the eye muscles (also called extraocular muscles- they control movement of the eyes) and the brain. Transfer of signals from the brain to eye muscles is also hindered when there’s a defect in the nerves.
Medical conditions that result in double vision are:
- Dryness in cornea, corneal infections, scars on the cornea
- Dislocated lens - Marfan's syndrome
- Lens problems- cataract
- Refractive error - astigmatism
- Misalignment of eyes since childhood
- Trauma of extraocular muscles due to brain problems like brain tumour, multiple sclerosis, stroke, head trauma, aneurysms, migraine headaches, tiredness
- Weakness in eye muscles from diseases like Myasthenia Gravis, diabetes, Grave’s disease
- Damage to nerves that control eye co-ordination in case of diabetes, Guillain-Barre syndrome, etc.
Diagnosis of double vision
You need to visit an eye specialist for this. Diagnosis begins with evaluating the history of double vision. Some questions you would probably need to answer are:
- Since when you are observing
- Duration and frequency of double vision
- Nature of double vision
- Any previous or recent medical condition
- Other symptoms like eye pain, headache, etc.
Your eyes will be examined in determining monocular or binocular double vision and presence of other abnormalities. Physical examination of the eyes also entails measuring visual acuity, observing the movement of pupils, and checking the alignment of eyes with the help of various types of diagnostic instruments.
Furthermore, blood tests may be suggested along with a CT scan and MRI of the brain and eye muscles to confirm the underlying disorder that’s resulting in double vision.
Treatment of double vision
Once the nature and cause of double vision has been determined, treatment follows in accordingly. The strategies involved in correcting double vision are:
- Corrective lens – Refractive error in the eyes can be resolved with the help of corrective glasses or contact lenses. Special prisms, called Fresnel prisms may be attached to glasses to manage binocular double vision
- Treatment also involves curing the underlying problems like that of nerve damage, brain injury and lens disorders. A surgery is usually recommended for this purpose
- A minor dose of Botulinum toxin may be injected in the eye muscles to treat extraocular muscle abnormalities and restore proper movement of the eyes.
- Apart from those, the eye specialist might prescribe eye drops to treat dryness and infections or ask to you wear an eye patch temporarily and advise some eye exercises.
We suggest you toget your eyes checked on experiencing any kind of vision problems.
Written by: Saptakee sengupta
Date last updated: April 28, 2015