Double vision, also known as diplopia, is the condition of seeing two images of a single object. Potential double vision causes may affect different parts of the visual system - the eyes, nerves, muscles, or brain. The root cause is key to diagnosing and treating the disorienting condition.
Double Vision Classification
Diplopia, or double vision, can be categorized into several types based on its presentation:
Monocular Diplopia
In monocular diplopia, double vision persists even when you close one eye. Seeing double is typically caused by problems within the affected eye, such as refractive errors, cataracts, corneal abnormalities, or lens dislocation.
Binocular Diplopia
Double vision occurs when both eyes are open and resolves when one eye is closed. Common causes are problems with the cranial nerves. Sub-types depend on the position where you see the double image: Horizontal, Vertical, Oblique/Diagonal.
Physiological Diplopia
A normal phenomenon when objects outside the area of focus are perceived as double. For example, if you're looking at a near object, background objects may appear duplicated, and vice versa.
External Double Vision Causes
1. Exhaustion
Physical and mental exhaustion can cause temporary double vision due to eye fatigue.
How exhaustion causes diplopia: Prolonged tiredness, overworking, or lack of sleep can weaken the eye muscles. Eye strain may also happen after intense long periods of focusing on something, reading, or looking at a screen. The eye fatigue may cause mild binocular double vision.
Additional symptoms:
Blurred vision
Eye strain
Headaches
Dry eyes
Sensitivity to light
Difficulty focusing
Risk group: Anyone who is overworked, sleep-deprived, or experiencing high levels of mental or emotional stress.
2. Intoxication (Alcohol or Drugs)
Intoxication from alcohol or drugs impairs the brain, the nervous system, and the body’s functions - motor control, coordination, and vision.
How intoxication causes diplopia: Alcohol and certain drugs depress the central nervous system. As a result, affecting how the brain processes visual signals and weakens the control of eye muscles. When ocular muscles don’t coordinate, the eyes may misalign, leading to temporary double vision.
Additional symptoms:
Blurred vision
Slurred speech
Impaired coordination
Slow reaction times
Dizziness
Nausea
Risk Group: Anyone who consumes alcohol in excess or uses sedatives, stimulants, or hallucinogens.
3. Medication Side Effects
Prescription or over-the-counter meds can cause adverse reactions across the systems in the body. So visual disturbances may occur as side effects.
How medication side effects cause diplopia: Some meds cause eye muscle weakness or affect the brain’s ability to process visual signals. The medications that can potentially cause double vision as a side effect are anticonvulsants, antidepressants, muscle relaxants, antihistamines, and drugs for hypertension.
Additional symptoms:
Blurred vision
Dizziness
Dry mouth
Drowsiness
Difficulty concentrating
Fatigue
Risk group: People on medications that influence the central nervous system or affect blood flow, muscle control, or nerve function.
4. Orbital Fracture/Eye Injury
An orbital fracture is a break in one of the bones surrounding the eye. Such type of fracture comes from trauma, car accidents, falls, injuries at work, or sports injuries.
How orbital fracture causes diplopia: A fracture can trap muscles or nerves around the eye, preventing normal eye movement and causing double vision.
Additional symptoms:
Swelling around the eye
Bruising
Restricted ocular movements
Possible vision loss
Risk group: People with facial trauma.
Internal/Medical Causes of Double Vision
5. Strabismus
Strabismus, or "crossed eyes," is a type of eye misalignment, where one eye may point in a different direction (upward, downward, inward, or outward) from the other.
How strabismus causes diplopia: Due to the misalignment of the eyes, they send two different images to the brain. In adults, this leads to double vision. In children, the brain may suppress the image from the misaligned eye to avoid double vision, which can result in amblyopia (lazy eye).
Additional symptoms:
Difficulty with depth perception
Eye strain
Headaches
Squinting to see clearly
Risk Group: Children. Strabismus can also develop in adults due to trauma, nerve damage, or health problems.
6. Astigmatism
Astigmatism is a refractive error, caused by an irregular shape of the cornea or lens. Instead of a round eye, people with astigmatism have a slightly oval or cylindrical eye causing uneven light focus.
How astigmatism causes diplopia: The uneven surface of the cornea or lens causes light entering the eye to scatter, creating multiple focus points. That's how double vision occurs in one eye (monocular diplopia)
Additional symptoms:
Blurriness
Difficulty seeing clearly at any distance
Excessive halos and glare around lights (especially at night)
Eye strain
Headaches
Risk group: People of all ages. Can occur alongside nearsightedness or farsightedness.
7. Cataracts
Cataracts are spots or specs clouding the eye’s lens, which in normal instances should be clear. The condition is associated with aging but can also develop due to injury, prolonged UV exposure, or medications.
How cataracts cause diplopia: Cataracts scatter the light entering the eye. When it happens, the person can experience blurriness or monocular double vision.
Additional symptoms:
Partial visual obstruction
Blurry vision
Trouble seeing at night
Sensitivity to light
Seeing faded, greyish, or yellowed colors
Risk group: Older adults, though cataracts can develop at any age due to trauma or genetics.
8. Diabetic Neuropathy
Diabetic neuropathy is a type of nerve damage from long-term high blood sugar levels. The condition can interfere with the cranial nerves, vital for the movement of the eyes.
How diabetic neuropathy causes diplopia: Impairment of the nerves that move the eyes may cause them to misalign, due to which a person may start to see double.
Additional symptoms:
Numbness
Tingling
Pain in the extremities
Blurred vision
Difficulty moving the eyes together
Risk group: People with poorly managed or long-term diabetes.
RELATED: Eye Risks When You Have Diabetes
9. Keratoconus
Keratoconus is an eye condition in which the clear front part of the eye (cornea) is thin and cone-shaped, distorting vision.
How keratoconus causes diplopia: The irregular shape of the cornea causes light to scatter in multiple directions. People with keratoconus may notice blurry vision or double vision in one eye (monocular diplopia)
Additional symptoms:
Light sensitivity to light
Blurriness
Frequent changes in eyeglass prescriptions
A constant need to rub the eyes
Risk group: Young adults and people with a family history of the condition.
10. Myasthenia Gravis
Myasthenia gravis is a neurological autoimmune disorder causing muscle weakness. This happens by disrupting the signal transmission between nerves and muscles, sometimes those controlling the eyes and face.
How myasthenia gravis causes diplopia: Weakness in the eye muscles misaligns the eyes, hence the binocular diplopia.
Additional symptoms:
Drooping eyelids (ptosis)
Muscle fatigue
Difficulty speaking or swallowing
General weakness that worsens with activity
Risk group: Adults, particularly women under 40 and men over 60.
11. Multiple Sclerosis (MS)
MS is a chronic autoimmune condition that attacks the central nervous system. As a result, it damages the protective myelin sheath (protective membrane) around nerve fibers and impairs communication between the brain and body.
How MS causes diplopia: MS may affect the function of the cranial nerves. Thus misaligning the eyes and causing binocular double vision.
Additional symptoms:
Blurry vision
Loss of coordination
Muscle weakness
Fatigue
Difficulty walking or maintaining balance
Risk group: Adults, particularly women.
RELATED: Eye Health and Chronic Diseases
12. Aneurysm
An aneurysm is a bulging or ballooning in the wall of a blood vessel. A brain aneurysm can put pressure on the nearby nerves.
How an aneurysm causes diplopia: If an aneurysm presses on the cranial nerves that control eye muscles, it can bring on eye alignment problems and seeing double.
Additional symptoms:
Severe headaches
Eye pain
A drooping eyelid
Vision loss if the aneurysm ruptures
Risk group: Adults with high blood pressure, smoking habits, or a family history of aneurysms.
13. Brain Tumor
Benign and malignant tumors in the brain can press on the areas responsible for vision or on the cranial nerves.
How a brain tumor causes diplopia: Pressure from the tumor can affect the nerves or muscles controlling the eye's alignment.
Additional symptoms:
Headaches
Seizures
Loss of vision in one or both eyes
Nausea
Vomiting
Problems with balance or speech
Risk group: People of all ages. The likelihood increases with age.
14. Stroke
Blood flow interruption to a part of the brain can cause a person to have a stroke. Stroke damages the brain tissue and can impact any part of the brain, even the areas responsible for vision.
How stroke causes diplopia: A stroke affecting the brainstem or cranial nerves can disrupt eye coordination. When the eyes no longer move together, the person experiences binocular diplopia.
Additional symptoms:
Sudden weakness or numbness on one side of the body
Difficulty speaking or understanding speech
Vision loss
Severe headache
Risk group: Older adults, people with hypertension, and a history of cardiovascular disease.
RELATED: Eye Damage from Stroke
15. Graves’ Disease
This autoimmune disorder causes the thyroid gland to produce too much thyroid hormone (hyperthyroidism). It can also trigger thyroid eye disease (Graves' orbitopathy) with inflammation of the ocular muscles and tissues.
How Graves' disease causes diplopia: Swelling of the muscles around the eyes restricts ocular movement, causing eye alignment issues and seeing double.
Additional symptoms:
Bulging eyes
Eye irritation
Light sensitivity
Difficulty closing the eyelids
Risk group: People with thyroid problems, particularly women. People with a family history of autoimmune disorders are also at risk.
16. Cranial Nerve Palsy
Cranial nerve palsies occur when the nerves controlling eye motions malfunction. The three main nerves involved are the oculomotor nerve (cranial nerve III), trochlear nerve (cranial nerve IV), and abducens nerve (cranial nerve VI).
The oculomotor nerve controls most eye movements and the upper eyelid. The trochlear nerve regulates the muscles responsible for downward and inward eye movement. The abducens nerve controls the lateral rectus muscle, which moves the eye outward.
How cranial nerve palsy causes diplopia: Trauma, diabetes, or other conditions may damage these nerves, restricting eye movement and triggering double vision.
Additional symptoms:
Misaligned eyes (strabismus)
A drooping eyelid (ptosis)
Difficulty moving the eyes together
Risk group: People with diabetes, head injuries, and stroke survivors.
In Summary...
If you see double, get that checked out. A visit to your eye doctor can pinpoint what's going on and get you on the right path to treatment. Catching the problem early makes a big difference in protecting your vision and eye health.
Resources:
Diplopia (Double Vision), Yale Medicine
Surprising Facts About Diabetes and Your Eyes, American Academy of Ophthalmology
Myasthenia Gravis, EyeWiki
MS eye and vision problems, MS Society
Change in vision from Brain Tumor, The Brain Tumor Charity
Vision problems after stroke, Stroke Association
Graves' disease, Mayo Clinic
Cranial Nerve Palsy, American Association for Pediatric Ophthalmology and Strabismus
✅ Medically reviewed
Checked by Atanas Bogoev, MD.