The medical term for double vision is diplopia and it is a symptom to take seriously. While some causes of double vision are relatively minor, others need immediate medical attention. Let’s takes a look at the causes, symptoms, and treatments for double vision.
Your Vision System
Being able to see clearly depends on multiple areas of your vision system working together. Your vision system consists of:
- Incoming light is focused by the cornea, the outside layer of the eye.
- The pupil is a contractile aperture or lens, which also helps focus light.
- Behind the pupil is a lens, which also helps focus light.
- The retina is the light absorbing back wall of the eyeball.
- Muscles around the eye (extraocular) rotate the eyeball.
- Optic nerves carry visual information from the eyes to the brain.
- The brain is where visual information from the eyes is coordinated and processed.
Problems with any one part of this system can lead to double vision. Double vision is not normal and should be reported promptly.
Causes of Double Vision
Each part of the vision system has its own unique problems.
Cornea problems: Corneal problems often cause double vision in just one eye. This is shown by covering the affected eye, which makes the double vision go away. The surface of the eye may become damaged, which distorts incoming light and can cause double vision. This type of damage can happen in several ways:
- Accidental trauma
- Herpes infection of the cornea
- Shingles infection of the cornea
- LASIK surgery can alter the surface of one cornea (uncommon complication)
- Lens problems: The most common problem with the lens is cataracts. If cataracts are present in both eyes, images from both eyes will be distorted. Typically cataracts can be corrected with minor surgery.
- Muscle problems: If a muscle in one eye is weak, that eye may not move in a coordinated way with the healthy eye, which can cause double vision. Muscle problems can result from:
- A thyroid condition called Graves’ disease can weaken eye muscles. Graves’ disease commonly causes vertical diplopia, where one image is on top of the other.
- An autoimmune illness called myasthenia gravis blocks the stimulation of eye muscles by nerves. Early symptoms of myasthenia gravis are often double vision and drooping eyelids.
- Nerve problems: Double vision may be caused by nerve damage caused by:
- Multiple sclerosis can affect nerves anywhere in the brain or spinal cord. If the nerves controlling the eyes are damaged, this can result in double vision.
- Guillain-Barre syndrome is a neurological disorder in which the body’s immune system attacks the nerves. Sometimes, the first symptoms occur in the eyes and cause double vision.
- Uncontrolled diabetes can lead to nerve damage in one of the eyes, causing eye weakness and double vision.
- Lyme Disease can cause weakness of nerves that supply the head often causing facial drooping and double vision.
- Brain problems: The processing of visual information takes place inside the brain. Many different causes for double vision originate in the brain. They include:
- Brain tumors
- Increased pressure inside the brain from trauma, bleeding, or infection
- Migraine headaches
How Is Double Vision Diagnosed?
With so many serious possible causes for double vision, it’s important to discover the reason without delay.
Your doctor will most likely use multiple methods to diagnose the cause for your double vision. A physical exam, blood tests, and possibly imaging studies like computed tomography (CT) or magnetic resonance imaging (MRI), are often used in diagnosis.
One of the most effective tools in diagnosing double vision is the information you provide. You can make the diagnosis more accurate by answering the following questions beforehand.
- When did the double vision start?
- Is the double vision worse at the end of the day or when you’re tired?
- Do you tend to tilt your head to one side? (Ask your family about this one — you may not be aware of doing this.
- Have you hit your head, fallen, or been unconscious?
- Were you in a car accident?
- Have you had any other symptoms besides double vision?
Now, focus on a specific object in your field of vision.
- Are the two objects side by side, or is one on top of the other? Or are they slightly diagonal?
- Are both images clear or is one image blurry and the other clear?
- Does covering either eye make the double vision go away?
- Pretend your field of vision is a clock face. Move your eyes around the clock, from noon to six and up to 12 again. Is your double vision worse at any clock position? Does any position make your double vision improve?
- Tilt your head to the right, then to the left. Do any of these positions improve the double vision, or make it worse?
How Is Double Vision Treated?
The most important step in treating double vision is to identify the underlying cause. In some cases, double vision can be improved by managing or correcting its cause.
- Graves’ disease is often curable with surgery or medical therapy.
- If an eye muscle has been pinched as a result of injury, surgery may help.
- Myasthenia gravis can be treated with medications.
- The blood sugar imbalance of diabetes can be controlled with medicines and/or insulin.
If your double vision can’t be reversed, there are treatments that may help you live with double vision. Sometimes, this requires eye exercises, wearing an eye patch on alternative eyes, prism lenses, or special contact lens to minimize visual effects. In extreme situations surgery or botulinum toxin has also proven successful.
Remember that the first step is to identify the underlying cause of the problem. Double vision that’s new or unexplained needs medical attention right away.
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