Double Vision

Double vision refers to seeing two images of a single object, wherein the images appear on top of the other, side by side, or both. There are numerous reasons that may lead to double vision, ranging from mild to severe, life-threatening causes. Double vision is medically known is diplopia. In contrast, polyplopia refers to three or more images of a single object overlapping each other.

The eyes created their own, marginally different images as the eyes slightly differ in physical locations. However, the brain makes it possible to see only a single image. The brain does this by controlling the eye muscles enabling the eyes to accurately point to an object. The brain will combine both images produced by the eyes, producing a single image. This process is also called fusion.

The structures in the eye all work together to help the brain in producing a single image. Problems with any of the following process may lead to double vision. The incoming light is focused by the cornea after the light rays are reflected off by an object. The lens will then focus the light onto the retina. The extraocular muscles, the eye muscles, will rotate the eyes, while the nerves send the signal to the brain for processing of visual information.

Types of Double Vision

There are three types of double vision, depending if one or both eyes are affected or ability to focus on an object:

  • Monocular double vision
    • Affects only one eye
    • Covering the affected eye will cause the double vision to disappear
    • Slight separation of images
  • Binocular double vision
    • Affects both eyes
    • Covering either of the affected eye will cause the double vision to disappear
  • Physiological double vision
    • Objects that are not focused on appear doubled, usually objects in the background
    • Common child complaint

Causes of Double Vision

When the eye structures are damaged, the eyes cannot be controlled properly.The following may lead to a perception of two images of a single object:

  • Cornea problems
    • Corneal scars
    • Corneal infections
    • Dryness of the cornea
  • Len problems
    • Cataracts
    • Dislocated lens
  • Eye muscle problems
    • Myasthenia gravis
    • Graves’ disease
  • Nerve problems
    • Multiple sclerosis
    • Uncontrolled diabetes
  • Brain problems
    • Migraines
    • Increased cranial pressure
    • Strokes
    • Aneurysms
    • Brain tumours
  • Refractive errors: near-sightedness, far-sightedness and astigmatism
  • Dry eye
  • Blood clot
  • Eye tumour
  • Eye injury or infection

Symptoms of Double Vision

Double vision is usually a symptom for an underlying condition. However, in some cases, other symptoms may manifest, including:

  • Eye misalignment in one or both eyes
  • Pain in one or both eyes upon movement, or around the eyes
  • Squeezing the eyes in an effort to see
  • Nausea
  • Headache, may be pounding and throbbing
  • Weakness in the eyes
  • Droopy eyelids

Treatment for Double Vision

Double Vision

Double Vision

Treatment will depend on the underlying cause. In minor cases, corrective measures may be taken. In more severe cases, surgery may be required. Visit an ophthalmologist or optometrist for proper treatment.

  • For refractive errors, prescription eyeglasses or contact lenses are required to remove the blur.
  • Infections are usually treated with antibiotics if caused by bacteria.
  • Artificial tears are typically prescribed for dry eyes.
  • In some cases, refractive surgery such as LASIK and PRK are required.
  • Some causes of binocular double vision are fatal and may require emergency medical assistance.

Double vision may signify a medical emergency, especially if caused by strokes or aneurysms. To learn more about symptoms of medical emergencies, enrol in First Aid Courses with workplace approved Training. Understanding double vision and its causes may help when taking first aid courses.


Double Vision (Diplopia) (2011). WebMD. Retrieved September 16, 2013, from


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