Diplopia or double vision

Diplopia or Double Vision

What is it?

Diplopia or double vision is a visual impairment consisting in perceiving two images of the same object. It can be horizontal, vertical, or diagonal, depending on the place where the dual images appear (beside, below, above, or diagonally with regard to the object).

There are also different types of strabismus that can cause double vision:

• Oculomotor nerve palsy
• Strabismus that appears after eye surgery
• Orbital trauma
• Thyroid disorders
• Some forms of child strabismus that last into adulthood
• Strabismus of the myopic patient
• Neurological diseases (such as myasthenia gravis)
• Sensory strabismus (occurs when one of the two eyes has very low vision)

Sometimes, diplopia only affects one of the two eyes (monocular) and does not disappear when covering it. This kind of double vision is usually associated with other diseases that affect eye structures, which prevent eyes from fusing images, hence resulting in double vision.

Symptoms

Sometimes, patients with double vision tilt their head to try to compensate for this fact or to see better, which may cause chronic cervical pain in the long run.

Generally, diplopia occurs because of strabismus or a disorder of ocular motility. In these cases, double vision is binocular (it disappears when we cover one patient’s eye) and may be:

• Constant: the patient sees double all the time.
• Intermittent: it is characterised by double vision of objects at specific times.

Treatments

Double vision involves a great difficulty in performing daily activities, thus causing a disability in the patient who suffers from it. The ophthalmologist assesses the most appropriate treatment according to the degree of deviation and features of strabismus. The surgery has a success rate of 90%:

• If strabismus affects both eyes (binocular), a specific surgery is recommended.
• If strabismus affects one eye (monocular), it is generally recommended to minimise the symptoms by using prisms, penalty systems, or special glasses.

Prior Examination

Complete eye exam with a specialist in strabology to assess the degree of deviation, as well as the type of strabismus. During the visit, the ophthalmologist rules out the presence of other diseases or refractive errors associated with strabismus. Sometimes specific tests are requested to assess the disease.

How can it be treated?

During surgery, eye muscles are manipulated so as to change their position, weaken, or reposition them in order to place the eye in the appropriate position. This procedure allows double vision to be avoided. It is a surgery which is performed under topical anaesthesia with sedation or general anaesthesia, depending on the needs of each patient. Surgery is performed on an outpatient basis, allowing the patient to return home after surgery.

In other cases, we recommend placing a prism on the glasses, as a transitional measure before surgery or as a solution for patients who do not want to undergo surgery. The prism changes the direction of the image, hence removing diplopia. If the patient shows a mild degree of double vision, prisms can be placed on normal glasses. In more severe cases, the use of press-on or Fresnel prisms is recommended. These adhere to the glasses on the lens and are lighter than conventional prisms.