Diplopia, better known as double vision is a visual symptom that can be minor or serious. Many of us take advantage of opening our eyes and seeing a single, clear image. It’s an automatic process that is working within our vision system. Everything works together and there is no problem. However, when something goes wrong and we begin to see double images, it could be a sign of a serious underlying problem and medical attention should be sought after immediately.
There are many types of Diplopia, as images can be off horizontally, vertically or diagonally. The condition can affect one eye, both eyes, or it can be temporary or voluntary.
Suppression plays a major role in double vision as the brain naturally tries to avoid it. When the brain accepts and uses two separate images, double vision is the result. However, the brain will eventually suppress one of the two images which will lead to the disappearance of diplopia. Many people accept this process without seeking medical attention. But it’s important to remember that your brain has tricked itself into thinking there isn’t a problem, and that the underlying problem is still lurking.
If you experience double vision, even if it’s minor or temporary, you should still consider seeing an ophthalmologist or neurologist.
Types of Diplopia
As mentioned above, there are several types of Diplopia. Let’s break down each to understand them better.
Binocular Diplopia - With binocular diplopia, double vision is the result of the misalignment of both eyes due to functional problems within the vision system.
Monocular Diplopia - With monocular diplopia, double vision occurs in only one eye and is due to a structural problem within the vision system. This type is much less common than the others.
Temporary Diplopia - Temporary diplopia is generally due to a traumatic event, head injury or intoxication by a substance such as alcohol.
Voluntary Diplopia - Many of us, at one time or another, have induced double vision. A great example is when viewing stereograms (optical illusion of depth that is created from a flat, two-dimensional image).
Depending on the underlying condition, whether it is due to a structural or functional problem with ones vision system, an event or a purposeful cause, you may suffer from one of the four types of diplopia.
Causes of Double Vision
As mentioned above, diplopia doesn’t just happen. There is usually a reason or a cause for the double vision. First, let’s break down our vision system, including the cornea, lens, muscles, nerves and brain, and go over possible causes for double vision.
Cornea problems - Our cornea is the clear outermost disc that covers the eye and allows in focused light. If a problem occurs within the cornea, it generally causes monocular diplopia. The damage on the surface of the eye distorts incoming light, causing the double vision. Usually, if an eye is covered, such as with an eye patch, the problem goes away immediately.
Lens problems - Our lens is located behind the pupil and focuses light onto the retina. One of the most common problems we experience with the lens is cataracts. Cataracts are known to cause double vision and can be corrected with surgery. Lens problems can occur in one or both eyes and may be diagnosed as binocular or monocular diplopia.
Muscle problems - The muscles in our eyes are known as extraocular muscles. The extraocular muscles perform our eye’s movements, so if one eyes muscle is weaker than the other, double vision can be the result. Conditions like Grave’s disease (a thyroid condition) or Myasthenia gravis (autoimmune disease) can contribute to extraocular muscle problems.
Nerve problems - Nerves within our eyes carry the visual data from our eyes to our brain. If these important nerves are damaged, double vision is the result. There are many different conditions, such as Multiple sclerosis and diabetes, that can cause or lead to nerve damage in the eyes.
Brain problems - Our brains do much more than think for us. There are many areas within the brain that help process visual information delivered from our eyes. As we just learned, the nerves transfer information from the eyes to the brain. However, once the information arrives, the brain takes over and continues processing the data. Many different problems originate in the brain, such as strokes, aneurysms, increased pressure from trauma, tumors, and migraines, and cause double vision.
Symptoms of Double Vision
Double vision can occur by itself, or accompanied by other symptoms as a result of an underlying problem. Additional symptoms may include:
Pain with eye movements, affecting one or both eyes
Pain around the eyes, such as in the eyebrows or temples
Headaches
Nausea
Droopy eyelids
Weakness in the eyes
Misalignment of one or both eyes, such as a wandering eye or cross-eyed appearance
Treatment of Double Vision
There are treatment options available to treat double vision. The key is figuring out the underlying cause and treating that problem first. Again, double vision is generally a symptom of another problem, so treatment may include:
