Diplopia is characterized by seeing double, two images instead of one. It is linked to a problem with the muscles that control the eye or the nerves that stimulate the muscles. Double vision can affect one eye, this is called monocular diplopia, or both: in this case, it is binocular diplopia.

Diplopia is a symptom that reveals a specific pathology that can range from simple fatigue to a more serious problem (neurological damage). This is why it is necessary to consult a doctor who can establish an accurate diagnosis and offer treatment to relieve the affected person.

There are two types of diplopia, and they do not have the same origin.

The so-called monocular diplopias, which affect only one eye and which persist when the eye not responsible for the disorder is closed. The cause is mainly ophthalmological damage:  

• corneal injury
• iris damage
• damage to the lens, such as cataracts (partial or total clouding of the lens)
• macular degeneration (the macula being the central area of ​​the retina)

The so-called binocular diplopias, in which both eyes are concerned. They disappear when one eye is closed. In this case, the coordination between the two eyes is not done correctly. The oculomotor muscles are affected. Most frequently involved:

• tiredness
• hypoglycemia
• excessive alcohol consumption
• vascular problems affecting the arteries in the eye or brain

Let us also quote:

• oculomotor paralysis of traumatic or vascular origin, or due to certain infections
• a muscle condition, such as myasthenia gravis (a relatively rare autoimmune disease of neuromuscular junctions) or endocrine myopathy
• heterophoria: a binocular vision disorder linked to variations in the balance of the oculomotor muscles. The deviation of the eye usually corrects spontaneously, but returns quickly with fatigue or alcohol intoxication.
• neurological diseases, including certain brainstem tumors or multiple sclerosis
• infectious diseases, such as botulism
• taking certain medications, such as hypnotics

It is easy to understand that the fact of seeing double is disturbing or even extremely annoying for daily activities, whether reading, driving, working, etc. It is therefore imperative to be taken care of quickly.

The treatment of diplopia obviously depends on the cause that is at the origin. The doctor will perform an ophthalmologic examination with a biomicroscope or on the fundus of the eye depending on the cause, and can make his diagnosis. A specific orthoptic test will allow him to determine which oculomotor muscle is deficient in the event of binocular diplopia.

To treat monocular diplopias, treatment is that of the cause:

• cataract treatment
• or surgical repair in case of iris damage

Regarding binocular diplopias:

• first, it is advisable to cover one eye with a blindfold, so that the person with diplopia can continue to live daily while awaiting recovery
• use a Fresnel prism which can stick to spectacle lenses, if diplopia persists 

The doctor may also suggest:

• to resort to medication: Mestinon or any other anticholinergic with prolonged action. Corticosteroids may also be needed. 
• or to perform surgery (in some cases of permanent paralysis)