Diplopia or double vision causes a single object to be perceived in two images.
The two images are usually identical and their possible location is:
- Vertical (one above the other)
- Tilted – a combination of horizontal and vertical with one rotation
- Horizontal (one next to the other), divided into:
- Crossed diplopia, in which the image of the field of view of the right eye is to the left of the image of the left eye (convergence of the visual axes).
- Uncrossed diplopia, in which the image of the field of view of the right eye is to the right of the image of the left eye (divergent visual axes).
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How does the eye work?
In order to see a single image clearly, coordination of different areas of the visual system is necessary.
The cornea is the transparent window in the eye and is responsible for focusing light.
The lens is located behind the pupil and allows focusing on the retina.
The eye muscles rotate the eye.
The nerves transmit the visual information from the eyes to the brain.
In the brain, there are areas that process the visual information from the eyes.
Problems with any of these structures can cause double vision.
Types of double images
There are two types of double vision: monocular and binocular.
Monocular diplopia are double visions in just one eye.
The double vision persists even if the other eye is covered. The visual defect does not disappear if you look in different directions.
This disorder is associated with problems of the cornea or retina.
Monocular diplopia can be caused by:
- Astigmatism
- Keratoconus
- Pterygium
- Cataract
- slipped lens
- Sty
- Laser surgery (PRK) on the eye, up to about a month after surgery
- Dry eyes
- Retinal problems
Binocular diplopia are double visions associated with a malposition of the eyes.
Double vision disappears when one of the two eyes is covered.
An eye muscle problem causes this disorder, including:
- Strabismus
- Damage to the nerves that control the muscles
- Diabetes
- Myasthenia gravis
- Thyroid diseases (Graves’ disease)
- Trauma to the eye muscles
Physiological double vision: Often objects that the person does not focus (objects in the background) appear twice.
This vision problem is usually not recognized because the patient’s brain can usually compensate for this disorder.
If a child complains of this visual disturbance, it is usually a physiological diplopia.
Transitory or temporary double vision
Temporary or temporary double vision often has the following causes:
- Alcoholic poisoning
- Benzodiazepines
- Opiates
- Antiepileptic drugs and anticonvulsants
- Concussion (traumatic brain injury)
- Tiredness and tired eyes
Double vision near and far
- If double vision occurs only during close vision, this disorder can be caused by refractive errors such as myopia and astigmatism.
- Double vision in the distance can occur in people who are farsighted, especially after looking at a nearby object.
What are the causes of double vision?
Corneal problems
The abnormal surface of the eye deflects incoming light and can cause double vision.
The damage can be done in several ways:
- Infection of the cornea, such as herpes zoster;
- Corneal fibrosis – can alter the cornea and lead to uneven visual images;
- Dryness of the cornea (dry eye) – can lead to double vision.
Patients with a fracture of the eye socket can observe diplopia.
Lens opacity
Cataract is the most common disease of the lens, leading to double vision, blurred vision and sensitivity to light.
Cataracts are usually corrected by surgery.
Muscle problems
If the muscle of one eye is weakened, this eye can no longer be moved so easily.
Aligning the eyes in the direction controlled by the weakened muscle leads to double vision.
Causes of muscular disorders:
- Myasthenia gravis – an autoimmune disease that blocks muscle stimulation by the cranial nerves; the first signs are often double vision and ptosis (drooping eyelids);
- Graves’ disease – a thyroid disease that leads to hyperthyroidism and affects the eye muscles. Graves’ disease can lead to vertical diplopia.
Taking beta-blockers can cause double vision.
Nervous diseases
Various diseases can damage the nerves that control the eye muscles, thereby leading to double vision:
- Multiple sclerosis can affect any nerve in the brain or spinal cord.
If the nerves that control the eyes are damaged, they can cause double vision. - Guillain-Barré syndrome is a nervous disease associated with the degeneration of the myelin sheaths that leads to progressive weakness. Sometimes the first symptoms that are noticeable in the eyes are: double vision and drooping eyelids.
- Untreated diabetes can cause nerve damage in one eye, leading to eye weakness and double vision.
Brain disorders
The nerves that control the eyes are directly connected to the brain.
Visual processing takes place inside the brain.
Possible reasons are:
- Stroke
- Aneurysm
- Increase in intracranial pressure after trauma, bleeding or infection (sinusitis)
- Brain tumor
What are the symptoms of double vision?
Double vision can occur alone, without further symptoms.
Depending on the cause, concomitant symptoms may occur, for example:
- Misalignment of one or both eyes (strabismus) – this problem occurs mainly in children, but in some cases can also affect adults;
- Eye pain during eye movements (for example, when infected by herpes zoster);
- dizziness – with excessive consumption of alcohol and opiates or after traumatic brain injury;
- pain around the eyes, for example, at the temples or eyebrows, occurs after an eye socket fracture;
- headache – if the patient suffers from hypertension, brain tumor or has suffered a stroke or trauma;
- nausea – in case of poisoning;
- weakness in the eyes and body (with myasthenia gravis or Guillain-Barré syndrome);
- drooping eyelids – if the patient suffers from Guillain-Barré syndrome.
Diagnosis of double vision
Initial test
The first step in diagnosing double vision is to determine who is affected:
- both eyes (binocular double vision)
- one eye (monocular double vision)
Eye test
First of all, the ophthalmologist begins to assess vision.
The doctor may ask to read the letters in an image while examining the position of the eyes and observing how they move.
Orthoptic examination: This is a series of tests to determine the muscle(s) that have paralysis and cause diplopia.
He must also check eye movement: whether the eyes move in a coordinated manner (binocular vision).
Examination with the ophthalmoscope: The doctor performs this examination to detect any abnormalities of the lens (cataracts) and retina (rupture or detachment).
The assessment related to clinical history and any other symptoms should lead to the determination of the cause of the double vision.
Further investigations
Blood tests can be done.
Images of the brain or eye muscles can be created by:
- a CT that emits a series of X-rays at slightly different angles and uses the computer to evaluate and display the data;
- magnetic resonance imaging (MRI), which uses a strong magnetic field and radio waves to produce detailed images of inside the body.
What to do? How is double vision treated?
Treatment of binocular double vision depends on the cause.
If an illness is the cause, for example a stroke, immediate treatment must be carried out in hospital.
Possible treatment options include:
- Natural remedies include special eye exercises.
- Prism glasses. A prism is an object made of glass or plastic in the shape of a cone that refracts light.
Special prisms, called “Fresnel prisms”, can be attached to the glasses and are an effective method of treating double vision.
One side adheres to the lens of the glasses and the other side has special grooves that change the angle of incidence of the light that enters the eye.
It may be necessary to wear the prisms for a few months.
The angle can be adjusted to suit the eye.
If the Fresnel prisms work, spectacle lenses can be produced with these aids. - Eye bandage. If one eye is bandaged, you feel an immediate improvement, but this is only a short-term solution.
- Wearing an opaque contact lens on one eye.
- Injections of botulinum toxin, these are drugs that paralyze the muscles.
This medication can be injected into one of the eye muscles.
The botulinum toxin works like a muscle relaxant and restores muscular balance to bring the eye into the right position.
This treatment lasts about 12 weeks and must be repeated afterwards.
Sometimes this treatment is done long-term and sometimes it serves to see if surgical correction can bring benefits. - Performing surgery of the eye muscles.
Surgery for diplopia or double vision
Surgical correction may be necessary to correct strabismus. The surgery involves strengthening or weakening eye muscles to balance the muscular balance of power so that the eye is placed in the desired position.
- If a muscle is not working effectively, the surgeon can remove a piece of it. In this way, more force is transferred to the eye.
- If a muscle exerts too much traction on one eye, it must be weakened. It must be separated from the eye and slightly offset where it exerts less force.
The procedure for strabismus is carried out under general anesthesia.
Sometimes a squint position regulates itself without treatment, so that double vision corrects itself.
This is especially the case with vision problems caused by a stroke. In most cases, strabismus passes after three to six months.
Motoring
People with diplopia are not allowed to drive. You are only allowed to get behind the wheel again when the competent medical authority certifies that this is possible.
Each state has its own laws regarding fitness to drive.
Recovery times for double vision (prognosis)
Paralysis of the sixth cranial nerve for vascular or unknown reasons usually resolves in 6-8 weeks.
Instrumental imaging is required if:
- the solution is not carried out within 2-3 months,
- the disease progresses,
- further neurological signs or symptoms develop.
- Headache of cervical origin or behind the eyes
- Eye pain and headache
- Multiple sclerosis: symptoms and complications
