What is Double Vision? (Binocular Diplopia)
If the two eyes are misaligned and aim at different targets, two non-matching images will be sent to the viewer’s brain. When the brain accepts and uses two non-matching images at the same time, double vision results.
Double vision is dangerous to survival, so, the brain naturally guards against its occurrence. In an attempt to avoid double vision, the brain will eventually disregard one of the mismatching images. That is, the brain will ignore one eye (called suppression).
Due to the brain’s ability to suppress one eye, a person’s double vision can appear to go away without medical evaluation or treatment. Bear in mind that the causes of the double vision are very likely still present and that loss of vision in one eye has probably occurred due to lack of treatment. When vision in one eye is lost, the person has also lost normal depth perception and stereo vision. However, the loss of vision could be temporary and treatable.
Double vision is not a minor complaint! When double vision occurs, seek a complete visual evaluation from a specialist in binocular (two-eyed) vision.
Causes of Double Vision or Diplopia
There are two possible and different causes:
- The most common cause of double vision is misalignment of the two eyesdue to functional problems in the visual system. This web page contains complete information on this type of double vision: binocular diplopia.
- A structural defect in the eye’s optical system is a much less common cause of double vision. Cataracts, for example, might cause such a defect. In this case, diplopia can appear in only one eye; this is called monocular diplopia.
Double vision can be a symptom of many different visual conditions that affect children and adults, such as strabismus (eye turns: exotropia, esotropia, hypertropia), convergence insufficiency or visual conditions related to head injuries.
Treatment of Double Vision
Treatment options include:
- Eye Muscle Surgery
- Orthoptics — Pre- and/or post-surgical
- Vision Therapy — Non-surgical or in conjunction with surgery, as appropriate (includes the use prism lenses).
Read parents’ and patients’ stories about getting rid of double vision with Vision Therapy at Double Vision Success Stories.
Double Vision and Head Injuries.
As mentioned above, double vision can occur as a result of an accident or head trauma. Double vision following a head trauma or brain injury can be cured. It is important to locate a specialist in binocular vision (two-eyed vision). Many eye doctors will offer only surgery. Be aware that effective non-surgical rehabilitation is available! Ask specifically whether the doctor provides visual rehabilitation of brain injuries or neuro-optometric rehabilitation.
Double Vision and Lazy Eye (Amblyopia)
If an eye turn is constant in infants or children, the suppressed eye can become amblyopic (lazy eye) from non-use. Amblyopia causes more visual loss in the under 40 group than all the injuries and diseases combined in this age group. Amblyopia also causes a loss of depth perception and stereo vision (stereopsis).
Although suppression of double vision can cause lazy eye, it is very important to understand that there are various causes and treatments for double vision and that crossed eyes and lazy eye are not the same condition.