The diplopia or double vision causes the vision of two images to a single object.
The two images are usually identical and can be:

  1. Vertical  (one image above the other)
  2. Oblique  – a combination of vertical and horizontal with a twist.
  3. Horizontal  (one side by side), in this case the diplopia falls into two groups.
  • Diplopia cruzada where the image of the field of view of the right eye is on the left respect to the image of the left eye (convergence of the visual axes).
  • Diplopia homonymous  in which the image of the field of view of the right eye is on the right respect to the image of the left eye (divergent visual axes).

 

How does the eye work?

To see only one clear image serves a coordination of the different areas of the visual system.
The cornea is the transparent window in the eyes and is responsible for focusing light on the retina.
The lens is behind the pupil and allows you to focus the light on the retina.
The oculomotor muscles cause the eye to rotate.
Nerves carry visual information from the eyes to the brain.
In the brain there are areas that process the visual information of the eyes.
Problems with one of these structures can cause double vision.

 

Types of double vision

There are two types of dual vision: binocular and monocular.

The monocular diplopia is double vision in one eye.
Double vision continues even when the other eye is covered. The vision defect does not disappear when you look in different directions.
This disorder is related to problems of the cornea or retina of the eye that remains open.
Monocular diplopia can be caused by:

The binocular diplopia is double vision due to a misalignment of the eyes.
The double vision disappears if one of the two eyes is covered.
A problem in the ocular muscles causes this symptom, among these are:

1. Strabismus ,
2. Damage to nerves that control muscles,
3. Diabetes ,
4. Myasthenia gravis,
5. Thyroid disease ( Basedow’s disease ).
6. Injuries to eye muscles.

Physiological double vision – often the objects that the person does not focus (objects in the background) appear double.
This vision problem often goes unnoticed because the patient’s brain can usually compensate for this type of symptom.
When a child complains of vision, he usually has a physiological diplopy problem.

Temporary or transitional double vision

Occasional or temporary double vision is often caused by:

  • Alcohol poisoning ,
  • Benzodiazepines,
  • Opiates,
  • Some medications for seizures and epilepsy ,
  • Concussion ( cranial trauma ),
  • Fatigue and tired eyes.

 

Double view from near and far

  1. Double vision only closely can be caused by refractive defects such as myopia and astigmatism .
  2. Double vision from afar can occur in people who suffer from farsightedness , especially after they have looked at a nearby object.

 


What Causes Double Vision?

Corneal Problems
The surface of the abnormal eye distorts the light received and can cause double vision.
Damage can occur in several ways:

  • Corneal infections , such as shingles ;
  • Fibrosis of the cornea that can alter the cornea creating unequal visual images;
  • Dryness of the cornea ( dry eye ) that can create double vision.

Patients who have had an orbital fracture can repair diplopia.

 

Crystalline disorders
cataract is the most common problem of the lens that causes double vision, blurred and sensitivity to light .
Cataracts usually resolve with surgery.

Muscle Problems
If the eye muscle is weak, that eye can not move with agility.
Stare in the direction controlled by the weak muscle causes double vision.

Causes of muscular disorders:

  • Myasthenia gravis is an autoimmune disease that blocks the stimulation of muscles by the nerves of the head;
    The earliest signs are often diplopia and ptosis (drooping eyelids);
  • Basedow Disease – Graves is a thyroid disorder that causes hyperthyroidismand affects the muscles of the eyes. Basedow’s disease can cause vertical diplopia.

Taking beta-blocker medicines can cause double vision.

Nerve
diseases Several diseases can damage the nerves that control the eye muscles and lead to double vision:

  • The multiple sclerosis can affect the nerves anywhere in the brain or spinal cord.
    If the nerves that control the eyes are impaired they can cause double vision.
  • The Guillain-Barre syndrome is a disease associated with degeneration of nerve myelin sheaths that causes weakness progressive.
    Sometimes the first symptoms that appear in the eyes are: double vision and palpebral ptosis.
  • The diabetes uncontrolled can cause nerve damage in one eye, causing weakness of the eye and double vision.

Brain Disorders
The nerves that control the eyes are attached directly to the brain.
Visual processing occurs within the brain .
The causes can be:

 

What are the symptoms of double vision?

Double vision can occur in isolation, with no other symptoms.
Depending on the cause, for example, there may be:

  • Misalignment of one or both eyes ( strabismus ) – this problem occurs in children, but sometimes it also affects adults;
  • Pain in the eyes  during eye movements (eg in the case of herpes zoster infection );
  • Dizziness or dizziness – in case of alcohol and opiate intoxication or after a head injury.
  • Pain around the eyes, for example in the temporal or eyebrows, occurs after a fracture of the orbit;
  • Headache  – if the patient suffers from high blood pressure , a brain tumor, had a stroke or a trauma;
  • Nausea – in case of intoxication;
  • Weak eyes and body (in the case of myasthenia gravis and  Guillain-Barré syndrome );
  • Fallen eyelids – If the patient is suffering from Guillain-Barré syndrome.

 

Diagnosis of double vision

Initial tests
The first step in the diagnosis of dual vision is to understand if it affects:
1. The two eyes (binocular double vision)
2. One eye (double monocular vision).

Vision Test
Usually the optometrist begins with the vision assessment .
Your doctor may ask you to read the letters in an image as he examines the position of the eyes and how they move.

Orthoptic Exam : A set of tests performed to locate muscle or muscles that have paresis and cause diplopia.

You need to evaluate ocular motility : if the eyes move in a coordinated way (binocular vision).

Examination with the ophthalmoscope : Your doctor will perform this examination to evaluate any abnormalities of the lens (cataract) and retina (retinal detachment or detachment ).

The assessment along with the medical history and any other symptoms help determine the cause of double vision.

Other exams

Blood tests may be done  .
Images of the brain or eye muscles can be obtained with:

  • computerized tomography (CT) scan  that sends a series of x-rays at slightly different angles, using a computer to process and view the data.
  • magnetic resonance imaging ( MRI ) that uses a strong magnetic field and radio waves to produce detailed images of the body.

 

What is the treatment for double vision?

Treatment for binocular double vision depends on the cause.
If the cause is a disease, such as a stroke , immediate treatment is needed at the hospital.
Possible treatment options include:

  • Among the natural remedies are the special exercises for the  eyes;
  • Prismatic eyeglasses. A prism is a wedge-shaped glass or plastic object that deflects light.
    Special prisms called “Fresnel” can be attached to the glasses and are an effective method for treating double vision. One side connects with the lens of the glasses and the other side has special grooves that modify the angle of light that enters the eye. It may be necessary to use the prisms for several months . The angle can be adjusted to fit the eyes. If Fresnel prisms work, glasses can be made with these instruments.
  • Using an eye patch , covering one eye, feels immediate relief, but it is a short-term solution.
  • Use an  opaque contact lens in one eye.
  • The injections of botulinum toxin are drugs that paralyze the muscles.
    This medicine may be injected into one of the oculomotor muscles.
    The botulinum toxin works as a muscle paralymer and restores muscle balance to move the eye into the correct position.
    This treatment lasts about 12 weeks and then should be repeated.
    It is sometimes used as a long-term treatment and sometimes it is done to understand if it is possible to have benefits with a surgical correction.
  • Perform surgery on the eye muscles.

 

Surgery for diplopia or double vision

Surgical correction may be necessary to correct strabismus.
The operation involves strengthening or weakening certain eye muscles to balance muscle strength, so the eye moves to the desired position.

  • If a muscle does not work effectively , the surgeon can cut a piece. In this way, it transmits more force in the eye.
  • If a muscle exerts a very strong pull on the eye, then it must be weakened, it must be removed from the eye and turned back further where it exerts a smaller force.

Strabismus surgery is performed under general anesthesia .

Sometimes strabismus is resolved without treatment, so the double view resolves itself.
This is especially true for vision problems due to stroke, in most cases strabismus will disappear after three to six months .

Driving
People with diplopia can not drive. You can start driving  when the competent medical authority certifies that it is possible.
Each state has its own laws about the ability to drive.

Recovery times for double vision (prognosis)

A paralysis of the sixth cranial nerve by unknown or vascular causes is usually resolved within 6-8 weeks.
Instrumental imaging tests are required if:

  • The resolution does not occur within 2-3 months,
  • The disease progresses,
  • Other neurological symptoms or signs develop.

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