We depend quite heavily on clear vision to navigate our daily lives. Unfortunately, this means our days can be seriously impacted by a lack of visual clarity. Double vision, for instance, can be a potentially life-threatening condition depending on exactly where and when you first experience it. Granted, it’s unlikely to be too harmful if you’re simply hanging out on the couch at home, but you certainly don’t want to be suddenly struck by this condition when speeding down the freeway. 

Double vision occurs when an individual perceives double images in place of a single object. Extra images may appear side by side, on top of one another, or in various combinations of configurations. This condition often affects balance, movement, reading ability, as well as focus and comprehension. If double vision affects only one eye, it’s considered monocular, but if it affects both, this is referred to as binocular. Many health problems can lead to this condition and we’ve chosen to highlight some of the most common causes here.

1. Corneal Distortions

The cornea is the layer in your eye that controls the amount of light sensed by your nervous system. Conditions such as astigmatism, dry eyes, infections (such as shingles or herpes zoster), or physical trauma (which causes scarring) may distort the corneal surface, thereby leading to double vision. Fortunately, corneal conditions can often be corrected with minimal intervention. 

2. Lens Issues

Another controlling mechanism in your eye is known as the lens. Located just behind the pupil, the eye’s lens focuses light directly onto the retina before it can be sent to the brain along the optic nerve. Conditions such as cataracts which affect the clarity of the lens can sometimes cause double vision. 

3. Muscle Weakness

Various tiny muscles control the movement of each individual eye. Six muscles must work together to allow you to move your eye up, down, sideways, or in rotation. Weakness or paralysis in any of these muscles can certainly affect their performance and can sometimes lead to double vision. Underlying medical conditions such as Graves’ disease (a thyroid condition that affects eye muscles and consequently causes vertical double vision) and strabismus (weakening or paralysis of eye muscles that prevents them from being aligned) are also factors. 

4. Neurological Conditions

Certain medical conditions affect nerves which link your eyes to your central nervous system, thereby causing double vision, among other complications. Diabetes, Guillain-Barré syndrome, myasthenia gravis, and multiple sclerosis are among the diseases which directly affect visual nerves, and these conditions sometimes cause double vision, as well. 

5. Traumatic Brain Injuries 

It may go without saying that brain injuries are likely to affect visual acuity. Because all sensory input is sent to the visual cortex via the central nervous system, any lesions or damage along the way will also affect the reception and interpretation of this input. Think of the brain like a computer’s central processor—all sensory information depends upon its proper functionality. 

Conditions such as tumors or aneurysms, blunt trauma, infections, strokes, or even simple migraines can exert pressure on the brain and affect its function. This pressure may short-circuit sensory signals, thereby altering how it interprets messages, potentially leading to double vision and other perceptual changes. 

While it may be temporary and somewhat harmless, double vision may be indicative of a more significant underlying health condition. This list of causes is by no means exhaustive; however, these factors are among the most common reasons for this condition. If you or a loved one has recently or is currently experiencing double vision, we highly recommend contacting us or your primary care physician immediately. We look forward to helping you correct any existing vision problems as soon as possible.