Patient Friendly Guide to Double Vision: Causes, Symptoms, and When to Get Your Eyes Checked

Double vision, also called diplopia, happens when you see two images of one object. The images may appear side-by-side, stacked, diagonal, tilted, or slightly shadowed. Sometimes double vision is mild and comes and goes. Other times, it can appear suddenly and make it difficult to read, drive, walk, or focus.

Because double vision can come from the eyes, eye muscles, nerves, or brain, it is important to take it seriously—especially if it is new, sudden, or worsening.

Eye doctor tests a boy’s vision while his mother waits in a bright clinic with eye chart and glasses display.

What Is Double Vision?

Double vision means the eyes and brain are not combining images properly. There are two main types: monocular double vision and binocular double vision.

Monocular Double Vision

Monocular double vision means the double vision remains even when one eye is covered. This type is often caused by an issue within one eye, such as:

• Dry eye

• Cataracts

• Corneal irregularity

• Astigmatism

• Prescription changes

• Problems with the tear film

This type may feel more like a shadow, ghost image, glare, or overlapping image.

Binocular Double Vision

Binocular double vision means the double vision goes away when either eye is covered. This usually means the two eyes are not lining up correctly.

Binocular double vision may be caused by:

• Eye muscle imbalance

• Strabismus

• Nerve problems

• Trauma

• Thyroid eye disease

• Diabetes or high blood pressure affecting eye movement nerves

• Neurological conditions

This type of double vision should always be evaluated, especially if it starts suddenly.

Common Symptoms of Double Vision

Patients may notice:

• Seeing two images of one object

• Images side-by-side, stacked, diagonal, or tilted

• Double vision that improves when one eye is covered

• Eye strain or headaches

• Trouble reading

• Difficulty driving

• Problems walking or going down stairs

• Closing one eye to see clearly

• Turning or tilting the head to reduce symptoms

The direction of the double vision can help the eye doctor determine which eye muscles or nerves may be involved.

Diabetes and Double Vision

Patients with diabetes can sometimes develop sudden double vision because of changes in the small blood vessels that supply the nerves controlling eye movement. This is called a microvascular cranial nerve palsy or diabetic ischemic nerve palsy.

This is different from diabetic retinopathy. Diabetic retinopathy affects the blood vessels in the retina, which is the light-sensitive tissue in the back of the eye. A diabetic nerve palsy affects one of the nerves that helps move the eyes.

When one of these nerves does not work properly, one eye may not move normally. The eyes may no longer point at the same target, causing double vision.

What Diabetic Double Vision May Feel Like

A diabetic patient may notice:

• Sudden double vision

• Double vision that goes away when either eye is covered

• Trouble looking to the side, up, or down

• One eye that feels like it is not tracking correctly

• Eye strain or headache

• Difficulty reading, driving, or walking

• A head turn or head tilt to reduce the double vision

In many cases, diabetic ischemic nerve palsies can improve over weeks to months, but they still need to be checked. New double vision should not automatically be blamed on diabetes because other serious causes may need to be ruled out.

Doctor explains double vision to a seated patient in an eye clinic, beside an eye chart and infographic titled DOUBLE VISION? GET IT CHECKED.

Other Causes of Double Vision

Double vision can happen for many reasons. Some are minor and treatable, while others require urgent attention.

Common causes include:

Dry Eye

Dry eye can cause fluctuating or ghost-like vision. Patients may notice that the double or shadowed image changes with blinking or improves temporarily with artificial tears.

Prescription Changes

Uncorrected nearsightedness, farsightedness, or astigmatism can sometimes cause blurry or shadowed vision. Updating glasses or contact lenses may help.

Cataracts

Cataracts can scatter light and create glare, halos, blur, or monocular double vision.

Eye Muscle Imbalance

Some patients have difficulty keeping the eyes aligned. This may become more noticeable with fatigue, reading, computer work, or aging.

Thyroid Eye Disease

Thyroid-related inflammation can affect the muscles around the eyes. This may cause pressure, bulging eyes, restricted eye movement, or double vision.

Stroke, Aneurysm, or Neurological Conditions

Sudden double vision can sometimes be a sign of a neurological problem. This is why new double vision, especially with other symptoms, should be taken seriously.

When Is Double Vision an Emergency?

Seek urgent medical care if double vision is sudden or occurs with:

• Severe headache

• New droopy eyelid

• A new enlarged or unequal pupil

• Weakness, numbness, facial droop, dizziness, or trouble speaking

• New vision loss

• Eye pain with swelling or redness

• Recent head trauma

• Trouble walking or loss of balance

• Confusion or difficulty staying alert

These symptoms may suggest a more serious medical or neurological condition.

How an Eye Doctor Checks Double Vision

During an eye exam, your optometrist may check:

Vision and Prescription

The doctor will check how clearly you see and whether glasses or contact lens changes could be contributing to symptoms.

Eye Alignment

The doctor will evaluate whether the eyes are pointing in the same direction and working together properly.

Eye Movements

The doctor will check how well each eye moves in different directions.

Pupil Testing

Pupil testing can help detect signs of certain nerve or neurological problems.

Prism Testing

Prism may be used to measure the amount of eye misalignment and determine whether prism glasses could help.

Eye Health Evaluation

The doctor may examine the cornea, lens, retina, macula, and optic nerve to look for eye-related causes of double vision.

Depending on the findings, the doctor may recommend monitoring, glasses changes, prism, dry eye treatment, referral, imaging, or additional medical evaluation.

Treatment Options for Double Vision

Treatment depends on the cause. Options may include:

Updated Glasses or Contact Lenses

If the double vision is related to prescription changes, astigmatism, or lens issues, updated correction may help.

Dry Eye Treatment

If the issue is caused by an unstable tear film, artificial tears or other dry eye treatments may improve vision quality.

Prism Glasses

Prism can help shift images so the eyes can work together more comfortably. Some patients need temporary prism, while others may benefit from permanent prism in their glasses.

Temporary Patching or Fogging One Lens

If double vision is very bothersome, temporarily covering one eye or fogging one lens may help reduce symptoms while the cause is being evaluated or while the nerve recovers.

Medical Treatment or Referral

If double vision is related to diabetes, high blood pressure, thyroid disease, inflammation, trauma, or a neurological condition, treating the underlying cause is important. Some patients may need coordination with their primary care doctor, endocrinologist, neurologist, ophthalmologist, or neuro-ophthalmologist.

Why You Should Not Ignore Double Vision

Double vision is a symptom, not a diagnosis. The important question is why it is happening.

Some causes are simple, such as dry eye or a prescription change. Others may involve the eye muscles, nerves, blood vessels, or brain. If double vision is new, sudden, worsening, or associated with other symptoms, it should be evaluated promptly.

Schedule an Eye Exam for Double Vision in Tampa

At OPT-ISM, we evaluate vision symptoms such as double vision, blurry vision, eye strain, headaches, and changes in eye alignment. If your double vision is sudden or associated with neurological symptoms, seek emergency care right away. For ongoing or intermittent double vision, a comprehensive eye exam can help identify the cause and guide the next step.