Double Vision or "Ghost" Images: What Causes It and When Is It an Emergency?

Double vision means you see two images of one thing, either side by side, stacked, or as a faint "ghost" shadow next to the real image. Most of the time it comes from something fixable in the eye itself, like astigmatism, dry eye or an out-of-date prescription. But double vision that starts suddenly, with both eyes open, can be a sign of a nerve, muscle or blood-flow problem, and that needs to be checked the same day.

I see patients with double vision every week. The first thing I ask is simple, and you can do it at home right now.

The one-eye test: does it go away when you cover an eye?

Look at the thing that's doubled, then cover one eye. Then cover the other.

• The double image stays even with one eye covered. This is called monocular double vision, meaning it comes from inside one eye. It's usually about how light focuses: the cornea (the clear front window), the lens, or the tear film. It's rarely an emergency, but it should be checked.
• The double image disappears when you cover either eye. This is binocular double vision. Each eye sees one clear image, but your two eyes aren't pointed at the same spot, so your brain gets two pictures. This is the kind that can point to a problem with the eye muscles or the nerves that control them.

Tell us which one you have when you call. It helps us decide how quickly you need to be seen.

What causes a "ghost" image in one eye?

Monocular double vision, the faint shadow or smeared second image, almost always comes from the front of the eye:

• Astigmatism. When the cornea is shaped more like a football than a basketball, light focuses in two places instead of one. Uncorrected or under-corrected astigmatism is the most common cause of ghosting I see, especially at night or when reading signs.
• An old prescription. Small changes add up. Glasses that were perfect three years ago can leave a shadow around letters today.
• Dry eye. The tear film is the first surface light passes through. When it's patchy, vision blurs and ghosts, and it often clears for a moment when you blink. You can read more in our post on why your dry eye drops stopped working.
• Keratoconus. The cornea slowly thins and bulges into a cone shape, which causes ghosting, streaks and multiple images that glasses don't fully fix. It often starts in the teens and twenties. Our keratoconus and scleral lens post explains how it's treated.
• Cataract. A cloudy lens can split light and create double or triple images in one eye, especially in bright light.

What causes double vision with both eyes open?

Binocular double vision happens when the eyes stop working as a team. Some causes are mild, and some are serious:

• An eye-turn that was always there. Some people have a small drift that the brain normally controls. When you're tired or sick, or after a drink, the eye can slip and you see double. This is common and treatable, sometimes with a prism (a special lens) in your glasses.
• Problems with the nerves that move the eyes. Diabetes and high blood pressure can affect the small nerves that control the eye muscles and cause sudden double vision. It often improves over weeks, but it needs to be checked and followed.
• Thyroid eye disease. Swelling of the muscles around the eye can limit how the eyes move.
• Myasthenia gravis. This muscle-weakness condition can cause double vision and a droopy eyelid that get worse as the day goes on.
• Stroke, aneurysm, head injury or a mass. These are rare, but they're the reason sudden binocular double vision is never something to wait out.

When should you see an eye doctor?

Call 911 or go to the emergency room right away if double vision starts suddenly and comes with any of these:

• a severe or "worst ever" headache
• a droopy eyelid or a pupil that looks larger than the other
• weakness, numbness, a drooping face or slurred speech
• trouble walking or loss of balance
• a recent head injury

Call us the same day if:

• double vision is new, even without other symptoms
• you see double with both eyes open and it doesn't go away
• your eye hurts, or the double vision came with redness or light sensitivity

Book a regular exam if you notice a faint ghost image in one eye that comes and goes, gets better when you blink, or is worse at night. It's very likely fixable, and an exam will show exactly why it's happening.

How do we figure out what's causing it?

An eye exam sorts this out quickly. We check:

• your prescription, carefully, including small amounts of astigmatism
• your tear film and the front surface of the eye
• the shape of your cornea, using corneal topography (a detailed map of the cornea's surface), which picks up early keratoconus
• how your eyes move and line up, looking straight ahead and in every direction
• your pupils and eyelids
• the back of the eye, including the optic nerve, with retinal imaging

If the pattern points to a nerve or muscle problem, we'll tell you clearly what we see and arrange the right next step with a neurologist, a neuro-ophthalmologist or your primary care doctor, depending on the cause.

How we do it at Bolt Eye Group

Every patient at Bolt Eye Group gets corneal topography and retinal photography for $39, so we can see causes like keratoconus and early cataract changes, not just guess at them. When the cause is in the eye itself, the fix is often simple: an updated prescription with the astigmatism fully corrected, treatment for dry eye, or specialty contact lenses such as scleral lenses for an irregular cornea.

We keep room for same-day visits for new or worrying symptoms at all five offices, on the days each office is open: Canton, East Cobb/Marietta, Lawrenceville, Riverdale and Johnson City, TN. We accept VSP, EyeMed, Davis Vision, Spectera, Medicare and major medical plans, including Blue Cross Blue Shield, Aetna, UnitedHealthcare, Cigna and Humana.

Frequently asked questions

Is double vision always serious?

No. Ghosting in one eye is usually caused by astigmatism, dry eye, an old prescription or cataract, and is very treatable. Sudden double vision with both eyes open is the type that needs urgent attention.

Why is my double vision worse at night?

Your pupils open wider in the dark, so light passes through more of the cornea and lens. Small focusing problems like uncorrected astigmatism, dry eye or early cataract show up more. Many patients first notice ghosting on headlights and street signs.

Can glasses fix double vision?

Often, yes. If the cause is astigmatism or an outdated prescription, new glasses can clear it. If the eyes are slightly misaligned, a prism ground into the lens can help them work together. Irregular corneas, as in keratoconus, usually need specialty contact lenses instead.

Can stress or tiredness cause double vision?

If you've always had a small eye-turn, being very tired can let it slip, so you may see double at the end of a long day. It's worth an exam to confirm that's what's happening, and to rule out other causes.

Should I drive if I'm seeing double?

No. Double vision affects depth perception and judging distance. If you must, cover one eye just long enough to get somewhere safe. Have someone else drive you to your appointment.

Book an exam at your nearest Bolt Eye Group office

If you're seeing double or noticing a ghost image, don't wait for it to settle on its own. Book an exam at Bolt Eye Group in Canton, East Cobb/Marietta, Lawrenceville, Riverdale or Johnson City, TN. Find your office and book online.