Quick Answer

Double vision, or diplopia, means seeing two images of one object instead of one. It can result from problems affecting the eyes, eye muscles, nerves or brain. Treatment depends on the cause and may include glasses, prisms, exercises, medicines or surgery. Sudden double vision needs prompt medical assessment.

Introduction

Seeing two images instead of one can be confusing and worrying, particularly when it happens suddenly or interferes with reading, driving or walking. Double vision, medically known as diplopia, is not a condition in itself. It is a symptom that can have several possible causes.

Sometimes double vision is related to the surface of the eye or an issue with the way light enters the eye. In other cases, it can occur when the two eyes are not working together properly. Less commonly, it may be associated with problems affecting the nerves, muscles or brain.

This guide explains the different types of double vision, common causes, how ophthalmologists diagnose the problem, treatment options and when you should seek urgent medical attention.

Key Takeaways

• Double vision is called diplopia and can affect one or both eyes.
• It may be caused by an eye problem, eye misalignment, muscle or nerve problem, or another medical condition.
• Covering one eye can help distinguish between monocular and binocular double vision.
• Diagnosis usually involves a detailed eye examination and may require further medical tests.
• Treatment depends entirely on the underlying cause.
• Sudden-onset double vision should be assessed promptly, particularly when accompanied by other neurological symptoms.

What Is Double Vision?

Double vision, or diplopia, occurs when a person sees two images of a single object. The images may appear side by side, one above the other, or at an angle.

Double vision can be temporary or persistent, depending on its cause. It can occur in children and adults and may affect one eye or both eyes.

A person with double vision may notice that the images separate more when looking in a particular direction. Some people also develop headaches, eye strain, dizziness or difficulty concentrating because the visual system is trying to deal with two images.

Double vision should not simply be assumed to be an eyesight prescription problem. Finding the underlying cause is important because some causes require medical or neurological assessment.

What Are the Two Main Types of Double Vision?

There are two broad types: monocular diplopia and binocular diplopia. The distinction can help an ophthalmologist identify where the problem may be coming from.

Monocular double vision

Monocular diplopia continues when one eye is covered and the other eye is viewing the object.

It can sometimes be associated with problems affecting the eye itself, including:

• Dry eye
• Astigmatism
• Cataract
• Corneal irregularities
• Problems with the lens
• Incorrect glasses prescription

The exact cause needs to be established through an eye examination.

Binocular double vision

Binocular diplopia occurs only when both eyes are open and usually disappears when either eye is covered.

It may happen when the eyes are not properly aligned or when the muscles and nerves controlling eye movement are not working together normally.

Possible causes include problems affecting:

• Eye muscles
• Cranial nerves
• The eye socket
• The brain or nervous system
• The alignment of the eyes

This distinction is one of the first things an eye specialist will consider when assessing double vision.

What Causes Double Vision?

Double vision has many possible causes, ranging from relatively common eye conditions to problems requiring urgent medical assessment.

Eye conditions

Problems affecting the eye’s optical system can sometimes produce double or ghost images. These may include cataracts, corneal irregularities, dry eye or significant astigmatism.

For example, changes to the lens of the eye can affect how light is focused onto the retina.

Eye misalignment

The eyes normally work together as a coordinated pair. If they point in slightly different directions, the brain may receive two images that do not line up.

Eye misalignment can result from conditions affecting the eye muscles, nerves or the structures around the eye.

Nerve-related causes

The nerves controlling eye movements are known as cranial nerves. If one of these nerves is affected, an eye may not move normally.

Possible causes include diabetes-related nerve problems, inflammation, trauma and other neurological conditions.

Thyroid eye disease

Thyroid eye disease can affect the tissues and muscles around the eyes. It may cause eye prominence, discomfort, restricted eye movement and double vision.

Myasthenia gravis

Myasthenia gravis is a condition that can affect communication between nerves and muscles. When the eye muscles are involved, double vision and drooping eyelids can occur.

Head injury

An injury involving the head or eye socket can affect the muscles, nerves or structures responsible for coordinated eye movement.

Other neurological conditions

Double vision can occasionally occur alongside neurological problems. The significance depends on the pattern of symptoms and the results of an examination.

For this reason, sudden or unexplained double vision should not be ignored.

What Symptoms Can Occur With Double Vision?

The most obvious symptom is seeing two images where there should be one. However, other symptoms can occur.

These may include:

• Headaches
• Eye strain
• Difficulty reading
• Difficulty focusing
• Dizziness
• Problems with balance
• Difficulty judging distances
• Drooping of one or both eyelids
• Eye pain
• Symptoms that become worse when tired

The pattern matters. For example, an ophthalmologist may ask whether the double vision occurs all the time, only at certain distances, or only when looking in a particular direction.

How Is Double Vision Diagnosed?

The diagnosis begins with a detailed history and eye examination. Further investigations may be recommended depending on what the examination shows.

1. Medical and symptom history

Your specialist may ask:

• When did the double vision begin?
• Did it start suddenly or gradually?
• Is it constant or intermittent?
• Is it worse when you are tired?
• Does it occur when looking near or far?
• Does covering one eye remove the double image?
• Are there headaches or eye pain?
• Have you experienced recent trauma?
• Do you have other medical conditions?

2. Visual acuity testing

Your vision may be measured using a standard eye chart. The specialist may check vision at different distances.

3. Eye alignment assessment

The position and movement of both eyes are examined to determine whether there is an eye misalignment.

4. Eye movement testing

You may be asked to follow a target in different directions. This helps the specialist assess how the eye muscles and nerves are functioning.

5. Slit-lamp examination

A slit lamp provides a magnified view of the front structures of the eye. It can help identify conditions affecting the cornea, lens and other structures.

6. Further investigations

Depending on the suspected cause, you may require additional tests or referral to another specialist.

These could include blood tests or imaging such as MRI or CT. The appropriate investigation depends on the individual clinical findings.

How Is Double Vision Treated?

There is no single treatment for double vision because treatment depends on its underlying cause.

Possible approaches include:

Treating an underlying eye condition

If double vision is caused by an eye condition such as cataract, corneal irregularity or significant dry eye, treatment may focus on that underlying problem.

Glasses

An updated glasses prescription may help when the problem is related to refractive error.

Prism lenses

Prisms can sometimes be incorporated into glasses to alter the path of light and help the two images line up.

They are not suitable for every type of double vision, and the prescription may need to be adjusted over time.

Eye exercises

In selected cases, specific exercises may be recommended by an appropriate eye-care professional. Their usefulness depends on the underlying diagnosis.

Treating medical conditions

If double vision is caused by another medical condition, treating that condition may help improve the visual symptoms.

Eye muscle surgery

Some forms of persistent eye misalignment may be treated with eye muscle surgery.

Whether surgery is appropriate depends on factors such as the cause, stability of the misalignment, eye movements and overall health.

Double Vision Treatment Options Compared

The appropriate treatment should be determined after identifying the cause rather than treating the symptom alone.

How Long Does Double Vision Take to Improve?

There is no single recovery time for double vision. Improvement depends on the underlying cause, how long the problem has been present and whether the condition is stable.

Your ophthalmologist can give you more specific guidance after assessing the cause.

What Factors Affect Treatment and Recovery?

Several factors can influence the management of double vision.

These include:

• The underlying diagnosis
• Whether the problem affects one or both eyes
• Whether the eye alignment is stable
• How long the symptoms have been present
• Whether the condition is improving or worsening
• Other medical conditions
• Previous eye surgery or trauma
• The response to initial treatment

A careful diagnosis is therefore more important than simply choosing a treatment based on the symptom of double vision.

Private Versus NHS Care for Double Vision

Both NHS and private ophthalmology services can provide assessment of eye problems, although the route to care, waiting times and costs may differ.

Through the NHS, your GP or another healthcare professional may assess your symptoms and arrange an appropriate referral where necessary.

Private ophthalmology can provide an alternative route for assessment, subject to the availability and scope of the individual specialist.

If you are considering private care in London, check what is included in the consultation, whether further investigations are available or arranged when appropriate, and what aftercare is provided.

How Should You Choose an Eye Specialist?

When seeking assessment for persistent or unexplained double vision, consider the following:

Check GMC registration

For medical treatment in the UK, check that the doctor is appropriately registered with the General Medical Council (GMC).

Consider relevant experience

Ask about the specialist’s experience with the type of eye problem you are experiencing and whether additional referral may be required.

Understand the diagnostic process

A good consultation should focus on identifying the cause rather than simply offering a treatment for the symptom.

Ask about treatment options

Depending on the diagnosis, there may be several possible management options. Ask about the expected benefits, limitations and risks of each.

Ask about aftercare

Find out how follow-up appointments are managed and who you should contact if symptoms change after treatment.

When Should You See a Specialist?

Seek prompt medical assessment if double vision starts suddenly, particularly if it occurs with other new symptoms.

Sudden double vision can sometimes be associated with conditions that require urgent assessment.

Seek urgent medical help if double vision occurs with symptoms such as:

• Sudden weakness or numbness
• Difficulty speaking
• Severe or unusual headache
• New problems with balance or walking
• Confusion
• Significant eye pain
• A new drooping eyelid
• Other sudden neurological symptoms
• Double vision following significant head or eye trauma

Do not drive if your vision is double or otherwise unsafe for driving.

If symptoms are persistent but not sudden, arrange an eye assessment so that the cause can be identified.

Frequently Asked Questions

What is double vision?

Double vision, or diplopia, is when a person sees two images of one object instead of one. It can affect one eye or both eyes and may have causes involving the eye, eye alignment, muscles, nerves or other parts of the body. Treatment depends on the underlying cause.

Is double vision serious?

Double vision can have many causes, some relatively minor and others requiring prompt medical assessment. Sudden-onset double vision is particularly important to assess, especially if it occurs with weakness, speech difficulties, severe headache, balance problems or other new neurological symptoms.

Can cataracts cause double vision?

Cataracts can sometimes cause visual disturbances, including glare, blurred vision or double or ghost images in one eye. However, double vision has many possible causes. An ophthalmic examination is needed to determine whether a cataract or another eye condition is responsible.

Why does my double vision disappear when I cover one eye?

If double vision disappears when either eye is covered, it is usually described as binocular diplopia. This can indicate that the two eyes are not properly aligned or coordinated. An eye specialist can assess eye movements and alignment to identify the likely cause.

Can glasses correct double vision?

Glasses can help some causes of double vision. For example, an appropriate prescription may correct a refractive problem, while prism lenses can sometimes help certain types of binocular diplopia. However, glasses are not suitable for every cause, so diagnosis should come first.

Can double vision be treated without surgery?

Yes. Depending on the cause, treatment may include glasses, prism correction, treatment of an underlying medical condition or observation. Some forms of persistent eye misalignment may eventually require surgery. The appropriate approach depends on the individual diagnosis.

How long does double vision last?

The duration varies considerably. Some cases improve as an underlying problem resolves, while others persist and require treatment. Double vision caused by eye alignment, nerve or muscle problems may follow a different course from double vision caused by an optical problem within the eye.

Should I drive if I have double vision?

You should not drive if you have double vision that affects your ability to see safely. Double vision can interfere with depth perception, visual concentration and awareness of other road users. If you develop persistent or sudden double vision, seek appropriate medical advice before returning to driving.

Conclusion

Double vision is a symptom rather than a single disease, and its causes can range from problems affecting the eye itself to issues involving eye alignment, muscles or nerves.

The most important step is to establish why the double vision is occurring. An ophthalmic assessment can help distinguish between monocular and binocular diplopia and determine whether further investigations or specialist referral are needed.

If you have persistent, unexplained or sudden double vision, particularly alongside other new symptoms, seek medical assessment promptly.

Mr Rajesh Deshmukh is a consultant eye surgeon based in Northwood, London. If you are concerned about changes in your vision, you can arrange an appropriate ophthalmic consultation to discuss your symptoms and the next steps.