Double vision

Diplopia aka Double vision

As neuro-ophthalmologists we are often asked to see patients for double vision aka diplopia. The patient can complain of constant or intermittent double vision.  It is important to be seen as soon as the diplopia is noticed since this can be a sign of a medical emergency. It is also important to make sure a trained eye care professional (often a neuro-ophthalmologist) evaluate the eyes and to determine the needed workup.

There are two main categories of double vision:

Monocular – the double vision is still present with one eye closed

This is usually not a neurologic problem but a problem in the eye itself (ie cornea, lens, retina)

Binocular – the double vision resolves with one eye closed and is only present with both eyes open

This is true neurologic double vision and is due to the misalignment of the two eyes. The easiest way to think of this is to imagine two cameras located just a few inches apart. Point them at an object in the distance and project the picture onto two screens. The two images will be similar but just slightly different since the cameras are viewing the object from different angles. In our brain the two images are lined up to make single vision. Now if the deviation of the cameras change (turn one towards or away from the other) the images become even more different and the brain cannot compensate. This causes the double vision.

When the deviation occurs in a young child, the brain will shut down the vision in one of the eyes to stop the double vision, often leading to a lazy eye if not treated in time. In adults however, the brain is unable to shut down the input from an eye so double vision occurs.

The causes of double vision are many but can include:

  • Cranial nerve III palsy (can be life threatening)
  • Cranial nerve VI palsy
  • Cranial nerve IV palsy
  • Myasthenia Gravis
  • Thyroid eye disease
  • Orbital trauma
  • Tumors of the orbit
  • Breakdown of a long-standing deviation

Once the workup shows the likely cause (sometimes easily seen with measurements, and sometimes other test are needed) then possible treatment can be prescribed. The treatment can include:

  • Patching of one eye
  • Prisms in the glasses
  • Botox to one of the eye muscles
  • Surgical intervention called strabismus surgery

 

Jody G. Abrams, MD

Oculoplastics/Neuro-Ophthalmology

Sarasota Retina Institute 

Sarasota, Florida