DIPLOPIA (Double Vision)

Diplopia, or double vision, is the simultaneous perception of two images of a single object. It can be horizontal, vertical, tilting, or a combination of all of these. Depending on the cause and severity, it can be intermittent or constant in nature, and is often disorientating and debillitating for the sufferer.

It can have many causes, but is usually the result of impaired function of one or more of the 6 extra-ocular muscles, where both eyes are still functional, but have lost the ability to work together as a pair.

The 6 extra-ocular muscles are the superior rectus, the inferior rectus, the medial rectus, the lateral rectus, the superior oblique and the inferior oblique.

These 6 extra-ocular muscles are innervated by 3 of the 12 cranial nerves-the third, fourth and sixth. If the nerves or muscles are prevented from working properly, this can result in diplopia.

Side view of the right eye, showing the extra-ocular muscles

Front view of the right eye

If you suddenly experience diplopia, you should seek a referral to your local eye clinic or A&E department, where you may need to have medical investigations to discover the cause of the diplopia.

The appropriate treatment for binocular diplopia will depend upon the cause of the condition producing the symptoms. In many cases, the diplopia is transient. However, the first concern must be to identify and treat the underlying cause of the problem.
Following this, most cases of diplopia are treated initially using temporary prisms, which can join the 2 images. Other treatment options include permanent incorporation of prisms into glasses, eye exercises, covering one eye, or if the symptoms are persistent, strabismus (squint) surgery and/or Botox injection


Strabismus is the correct term for any misalignment of the eyes. It is often called a squint, a crossed eye, or a turn in the eye. There are many different types.
Strabismus is usually categorised according to the direction of the turn. An inward (converging) turn is called an esotropia. An outward (diverging) turning eye is called an exotropia.

Vertical strabismus occurs when the eye turns downwards, called a hypotropia, or upwards, called a hypertropia. It is also possible but much less common for the eye to be twisted out or in. This is known as a cyclotropia.

Strabismus can occur in childhood or adulthood, depending on the cause.


Strabismus surgery is performed to re-align the eyes. It is done by weakening, strengthening or transposing one or more of the 6 extraocular muscles responsible for moving the eyes. General anaesthesia is used, with the patient often going home the same day the operation is performed.
The extraocular muscles are attached to the sclera, which is the wall of the eye. During surgery, the eyelids are held open using a speculum, and the muscle to be operated on is approached by first incising the conjunctiva, which is a thin, transparent layer, and then isolated using a small hook. There are no incisions to the skin around the eye, and the eyeball itself is never removed.
The most common procedures are muscle recessions or resections. A recession will weaken the action of the muscle by moving the insertion of the muscle further back from the front of the eye.

A resection strengthens the action of the muscle. The surgeon removes a portion of the muscle and then reattaches the insertion, thereby shortening the muscle and increasing it’s function.

Sometimes, adjustable sutures are used in order to finely tune the new alignment of the eyes. This is done by leaving a temporary knot in the muscle and then altering it later in the day or the following day, when the patient is awake. Local anaesthesia is used.

Is it painful?
The eyes can feel gritty and sore, particularly on eye movement, for a few days after the surgery. Generally, recovery post-surgery is very good.


The eyes a commonly affected following a stroke or head injury as the visual system travels from the eye itself to the very back of the brain. The most common defects include:

  • Double vision
  • Visual field loss, the loss of peripheral (side) vision on one side
  • Visual hallucinations, seeing objects or images that aren’t actually present.
  • Visual inattention, the loss of awareness of objects to one side, sometimes this can coincide with visual field loss.

These conditions can all be quite debilitating and often require treatment and rehabilitation with an Orthoptist.