Diplopia (double vision)

Diplopia is when you see two images of the same thing. Can be:

• Monocular diplopia – less severe and occurs when you see double with one eye open. Then a second image is formed – the “ghost image”.
• Binocular diplopia – double vision occurs when both eyes are open. The causes are usually more severe, neurological in nature.
• Horizontal diplopia – the double image forms from top to bottom.
• Vertical diplopia – the double image is formed from left to right.

To understand the causes of double vision, it’s important to understand the anatomy of the eye – the structure and role of each component.

The cornea works like a transparent window in your eye, with the main function of focusing light. If your double vision disappears when you cover one eye, but persists when you cover the other eye, you may have corneal damage in the eye with double vision.

O leziune la nivelul corneei poate fi cauzată de:

• Dryness
• Keratoconus, when the cornea becomes cone-shaped
• Infections, such as herpes or shingles
• Scars

The lens is located behind the pupil and helps focus light on the retina. The most common lens-related problem is cataract, which is almost always corrected by cataract surgery. The disease may be more severe in one eye and may progress differently in the two eyes.

Double vision affecting both eyes may involve:

Eye muscles – These control the movement of the eyeball and maintain the alignment of the eyeballs. If a muscle in one eye is weakened, it will not move in sync with the other eye. Therefore, when you look in one direction (controlled by the weakened muscle), you will see double.

Eye muscle problems can have causes such as:

• Problems with the nerves that control them.
• Myasthenia Gravis, an autoimmune disease that stops the nerves from telling the muscles what to do. Early signs include double vision and drooping eyelids.
• Graves’ disease, a thyroid condition that affects the eye muscles. It can cause vertical diplopia, in which one image is on top of the other.

Nerves – These transmit information from the brain to the eyes. Nerve problems are the main cause of double vision:

• Multiple sclerosis can affect nerves anywhere in the brain or spinal cord. If it affects the nerves that control the eyes, you may see double.
• Guillain-Barre Syndrome is a nerve disorder that causes growing weakness. Sometimes the first symptoms appear in the eyes, including double vision.
• Diabetes can cause nerve damage in the muscles that move the eyes, which can lead to double vision.

Brain – The nerves that control eye movement connect directly to the brain, where images are processed. Many causes of double vision originate in the brain, including:

• Strokes
• Aneurysms
• Increased pressure due to injury, bleeding or infection
• Tumors
• Migraines

In addition to double vision, diplopia may be associated with other symptoms such as:

•  Nausea (feeling sick or vomiting)
• Dizziness
• Headaches or discomfort when you move your eyes, in eyebrows or temples
• Blurred or fuzzy vision in one or both eyes
• Droopy eyelids
• One or both eyes not aligning properly (strabismus)
• Weakness in the eyes (or other parts of the body)

Before you make an appointment with your ophthalmologist, consider the following questions:

• When did the double vision start?
• Did you hit your head, fall or faint?
• Have you been involved in a car accident?
• Is double vision worse at the end of the day or when you are tired?
• Have you had any other symptoms besides double vision?
• Do you tend to tilt your head to one side to focus? You may not realize it, so it might be worth asking a friend or family member.
• Does double vision only occur when both eyes are open?

It can also help if you try to focus on a non-moving object (phone, lamp, tree, etc.) Ask yourself the following questions about double vision:

• Are the two images side by side or on top of each other? Are they slightly tilted? Which is higher or lower?
• Both images are clear, but not aligned? Or, is one blurry and the other clear?
• Cover one eye, then change. Does the problem disappear when you cover one eye?
• Imagine you have a clock in your visual field. Move your eyes from 12 o’clock to 6 o’clock and back to 12 o’clock. Is your vision better or worse in any position?
• Tilt your head right and left. Do any of these positions improve your vision, or make it worse?

During the ophthalmological examination, the doctor will carry out a full eye examination. This involves:

• A sensorimotor examination, which measures the alignment of the eyes in all directions
• An alternative coverage test that measures eye movement when focused on an object.

If eye misalignment is unusual, the specialist will perform further ophthalmological investigations.

To determine the cause of double vision, the doctor may ask:

• Blood tests
• Eye motility testing (helps the doctor determine eye movement limitations that may be caused by neurological conditions or other diseases)
• Imaging investigations (MRI, CT)

The ophthalmological treatment of diplopia differs, depending on the cause.

• If double vision is caused by weak eye muscles, or if a muscle is compressed due to an injury, ophthalmological surgery is recommended.
• Medicines can treat Myasthenia Gravis.
• Surgery and medicines can treat Graves’ disease.
• Medicines and insulin can keep blood sugar levels under control in cases of diabetes.
• Eye patches or glasses with prisms can relieve the effects.

Almost 70% of cases are treated with medicines or surgery. There are also situations when diplopia disappears on its own.

There are no specific ways to prevent double vision, but eye care and regular ophthalmological examinations are essential to detect vision problems early. Follow these tips to take care of your eyes:

• Don’t smoke.
• Take breaks from screens throughout the day.
• Wear computer glasses.
• Wear appropriate safety glasses if you participate in sports or activities that require it.

Go for annual control. The Dr. Holhoș ophthalmology network is present in Cluj-Napoca, Sibiu, Alba-Iulia, Turda and Mediaș, with top specialists and state-of-the-art technology.