Diplopia, commonly referred to as double vision, is a condition where a single object is seen as a double image. The two images can be side by side, one on top of the other, or a combination of both. Double vision can occur in one or both eyes. Diplopia, double vision, can cause problems with balance, movement and the ability to read. Double vision can inhibit an individual's ability to: drive an automobile or operative machinery, perform normal day to day living activities and remain gainfully employed. So what causes double vision and how do you manage it?

Diplopia (double vision) in one eye is known as 'monocular diplopia' – both imaged come from one eye. Monocular double vision is less common than binocular double vision and is typically the result of structural abnormality of the eye itself. Causes for monocular diplopia include:

• Abnormality of the lens, such as a cataract (clouding of the natural lens)

• Abnormality of the retina, as occurs with macular degneration

• Astigmatism, occurs when the eye's curvature is not spherical and causes distorted images

• Black eye (periorbital hematoma), double vision with a black eye can indicate a concussion

• Corneal problems, such as

  • Corneal scarring

  • Infections such as herpes zoster (shingles) or herpes simplex

  • Keratoconus

• Dry eye, dryness of the cornea can result in double vision (diplopia). Severe dry eyes, such as with Sjogren's Syndrome, can cause ghost images due to insufficient or poor quality tears.

Diplopia (double vision) in both eyes is known as 'binocular diplopia' – one image from each eye is seen, which results in two images. With binocular double vision, the double vision “goes away” if either eye is covered. Binocular double vision (diplopia) occurs because the two eyes point at slightly different angles, causing the eyes to send different images to the brain. The images from each eye are too different, or far apart, for the brain to create one single, clear image. This results in double vision.

There are many conditions that can cause binocular diplopia. Diplopia may be a symptom of:

• Accommodative Esotropia: Accommodative Esotropia is a type of strabismus and is the most common form of esotropia that occurs in children typically 2 years of age and older. When the child focuses the eyes in an effort to see clearly, the eyes turn inward. This crossing of the eyes can occur when focusing up close, far away (distance) or both.

• Aneurysm: An aneurysm is a bulge in a blood vessel. This can cause pressure on a nerve of the eye muscle.

• Brain tumor: A brain tumor, or growth behind the eye, can interfere with the movement of the eye and can cause damage to the nerves of the eye.

• Guillain-Barre Syndrome: Guillain-Barre Syndrome is a nerve condition that causes progressive weakness. One of the earliest symptoms of Guillain-Barre Syndrome occures in the eyes, and if often times double vision.

• Cancers: Certain cancers can interfere with the nerves that control the extraocular muscles (the muscles that move the eyes in different directions)

• Concussion: A concussion is an Acquired Brain Injury. A concussion can cause “bruising of the brain”, yet no structural damage is apparent, and can result in diplopia.

• Convergence Insufficiency: Convergence Insufficiency is the inability to align the eyes when focusing on a near object.

• Diabetes: Diabetes can lead to nerve damage affecting the muscles around the eyes. This can result in double vision.

• Exotropia: Exotropia, an outward-turning of the eye, is a type of strabismus. Exotropia occurs most often when the individual if focusing on objects in the distance. Exotropia can occur only from time to time, often times more noticeable when an individual is tired or not feeling well. Squinting one eye in bright sunlight is another symptom of exotropia.

• Graves Disease: Graves Disease is an auto-immune disease that affects the thyroid gland and the muscles of the eyes, commonly causing vertical diplopia (one image on top of the other)

• Head injury: Head injury can cause increased pressure inside the brain from trauma, bleeding or infection. This can result in diplopia.

• Infantile Esotropia: Infantile Esotropia occures when the eye turns inward, and is a common type of strabismus in infants. Young children with esotropia cannot use their eyes together.

• Microvascular Cranial Nerve Palsy: Microvascular Cranial Nerve Palsy affects the muscles of the eyes and inhibits the abilit to move the eyes in one or more directions, often times resulting in double vision (diplopia).

• Migraine Headaches: Migraines occur in 15-20% of the population, and up to 50% of women. Classic migraine headaches usually begin with visual symptoms (often colored lights or flashes of light) followed by a single-sided severe headache. Nausea, vomiting and light sensitivity typically accompany a migraine headache.

• Multiple Sclerosis: Multiple Sclerosis is a disease that affects the central nervous system, including the nerves of the eye. If the nerves controlling the eyes are damaged, double vision can occur.

• Myasthenia Gravis: Myasthenia Gravis is an auto-immune illness that causes weakness in the body's muscles, including those controlling the eyes. One of the earliest symptoms of Myasthenia Gravis is often double vision and drooping of the eyelids (ptosis).

• Ocular Migraine: Ocular Migraines begin with flashes of “jagged lines” or what looks like “heat waves” in both eyes. These symptoms typically last 10 to 20 minutes, and if not followed by a headache are referred to as an ocular migraine.

• Strabismus: Strabismus is a condition in which the eyes are not aligned properly and “point” in different directions. One eye may point straight ahead, which the other eye turns up, down, in, or out.

• Thyroid disease: Thyroid disease can damage or compress the eye muscles resulting in diplopia

• Transient ischaemic attack or cerebrovascular accident (commonly referred to as a stroke): With a stroke, the blood vessels supplying the brain or the nerves controlling the eye muscles can be affected.

Anytime diplopia, double vision, is noticed it is important to schedule an evaluation with a neuro-optometrist or neuro-ophthalmologist. This is an important first step to identify and treat the underlying cause. An eye doctor with specialized training in double vision, such as Dr. Ryan C. Johnson, will perform a thorough evaluation; which will include a detailed history and the use of multiple methods to diagnose the cause of the double vision. When the underlying cause has been determined, treatment can be prescribed and tailored to the the individual. Treatment of double vision often consists of: prism (incorporated into glasses), vision therapy (to improve one's compensating ability for occasional double vision), or surgery (to mechanically re-align the eyes and re-establish single vision). Most patients will benefit from a combined approach to treatment.

It is important to remember that diplopia (double vision) has many potentially serious causes. Diplopia requires immediate attention to rule out life-threatening conditions and diagnose the underlying cause.