Abnormal Eye Movements: Types, Causes and When to Worry

What counts as an abnormal eye movement

Six muscles move each eye. They are controlled by three cranial nerves (the third, fourth and sixth) and coordinated by the brainstem, cerebellum and inner ear balance system. Normally both eyes move together precisely, so you see one stable image. An abnormality anywhere along that chain changes how the eyes move.

You may notice it as:

• double vision, when the eyes point in slightly different directions
• shaking or bouncing vision (oscillopsia), when the eyes oscillate
• difficulty looking up, down or to one side
• eye strain, blurring or headaches after close work
• other people commenting that your eyes "wobble", "flicker" or "turn"

Types of abnormal eye movements

Nystagmus

Nystagmus is involuntary rhythmic eye movement. It can be side to side, up and down, or rotary.

• Infantile (congenital) nystagmus appears in the first months of life. Children rarely see the world moving, and many find a "null point", a head position where the shaking is least.
• Acquired nystagmus starts later and usually causes oscillopsia. Common causes are inner ear disorders such as vestibular neuritis and BPPV, alcohol, anti-seizure drugs and sedatives, and brain conditions affecting the cerebellum or brainstem.
• Vestibular nystagmus from the inner ear is typically suppressed when you look at a fixed target and gets worse when the eyes are closed or in darkness, which explains why some people notice symptoms worse with eyes closed. Nystagmus that changes direction or is purely vertical points more toward the brain.

Strabismus

Strabismus means the eyes are not aligned. In children it is usually present early and can cause lazy eye (amblyopia) if not treated, because the brain ignores the turned eye. In adults a new turn usually causes double vision and has a cause that needs investigating.

Cranial nerve palsies

• Third nerve palsy: the eye turns down and out, the eyelid droops, and the pupil may be large. A palsy with a dilated pupil is an emergency until an aneurysm is ruled out.
• Fourth nerve palsy: vertical double vision, worse looking down (for example on stairs). People often tilt their head to compensate. Head injury is a common cause.
• Sixth nerve palsy: the eye cannot turn outward, causing side-by-side double vision worse at distance. Causes include diabetes, high blood pressure and raised pressure inside the skull.

Nerve palsies from diabetes or high blood pressure ("microvascular" palsies) are common in people over 50 and usually recover within 3 to 6 months.

Causes of abnormal eye movements

In babies and children

• Infantile strabismus and accommodative esotropia (an inward turn caused by long-sightedness)
• Infantile nystagmus, sometimes linked to albinism or poor development of the optic nerve or retina
• Spasmus nutans: head nodding, head tilt and fine nystagmus that usually settles by age 3 to 4, but needs a scan to exclude a brain tumor
• Opsoclonus-myoclonus: chaotic eye movements with jerking limbs, sometimes linked to neuroblastoma

Inner ear and balance problems

Vertigo from BPPV, vestibular neuritis or Ménière's disease produces nystagmus during attacks, together with spinning dizziness and nausea.

Brain and nerve conditions

• Stroke in the brainstem or cerebellum
• Multiple sclerosis, a classic cause of internuclear ophthalmoplegia in younger adults
• Brain tumors and raised intracranial pressure
• Wernicke encephalopathy from severe thiamine (vitamin B1) deficiency, with confusion and unsteady walking
• Parkinson's disease and progressive supranuclear palsy, which limits looking down

Muscle and nerve-muscle junction disorders

Myasthenia gravis can mimic almost any eye movement problem. The clue is variability: double vision and drooping eyelids that worsen with use and improve after rest. Thyroid eye disease causes swollen, stiff eye muscles, bulging eyes and double vision, often looking up.

Medicines, alcohol and toxins

Alcohol, sedatives, anti-seizure drugs (phenytoin, carbamazepine), lithium and some recreational drugs cause nystagmus, especially when looking to the side. This is why police roadside tests include tracking the eyes.

Abnormal eye movements after concussion

Concussion often disrupts eye movement control. People notice trouble focusing on near work, eye strain, losing their place when reading and dizziness with busy visual scenes. Convergence insufficiency and slowed or inaccurate saccades (the quick jumps of the eyes between targets) are the most common findings. Clinicians use tests such as the VOMS (Vestibular/Ocular Motor Screening). Most recover within weeks; persistent problems respond to vision and vestibular therapy.

How abnormal eye movements are diagnosed

A doctor, optometrist or ophthalmologist will ask when it started, whether you see double (and whether it goes away with one eye covered), whether the world seems to move, and about head injury, medicines, alcohol and other symptoms. The exam usually includes:

• following a target in all directions to check range and smoothness
• cover tests to detect a turned eye
• checking the pupils, eyelids and the back of the eye for optic nerve swelling
• a neurological exam of speech, face, limbs and walking
• inner ear tests such as head-impulse testing and positional maneuvers

Depending on the findings, you may need:

• MRI of the brain, the key test for stroke, MS and tumors
• blood tests for diabetes, thyroid function and myasthenia antibodies
• CT or MR angiography if an aneurysm is possible
• videonystagmography to record and analyze nystagmus
• orthoptic assessment, measuring the size of a squint in different directions

Treatment

Treatment targets the cause:

• Children's strabismus: glasses, patching or atropine drops for amblyopia, and surgery on the eye muscles if needed.
• Double vision in adults: prism lenses on glasses, patching one eye short term, Botox injections into an eye muscle, or eye muscle surgery once the deviation has been stable for several months.
• Nystagmus: glasses or contact lenses for any refractive error, medicines such as gabapentin or memantine for some acquired forms, and occasionally surgery to move the null point straight ahead.
• Inner ear causes: repositioning maneuvers for BPPV and vestibular rehabilitation.
• Myasthenia gravis and thyroid eye disease: specific medicines and specialist care.
• Concussion-related problems: graded return to activity, vision therapy and vestibular therapy.

Frequently asked questions

What are the symptoms of an eye movement disorder?

The most common symptoms are double vision, a sense that the world is shaking or bouncing, blurred vision, eye strain, headaches with reading, trouble judging depth, and dizziness. Others may notice your eyes wobbling, flicking or turning. Some people, especially those with lifelong conditions, have no symptoms at all.

What are the main types of abnormal eye movements?

The main types are nystagmus (rhythmic shaking), strabismus (misaligned eyes), cranial nerve palsies, gaze palsies, internuclear ophthalmoplegia, saccadic intrusions such as opsoclonus, convergence insufficiency, and eyelid spasms such as blepharospasm. Each points toward a different part of the eye movement system.

Why do my eye movements get worse with my eyes closed?

Nystagmus from an inner ear problem is normally suppressed when you fix your gaze on something. With your eyes closed or in the dark, that suppression is lost, so the movement and the spinning sensation can increase. Nystagmus that stays strong despite fixing on a target is more likely to come from the brain.

Can a concussion cause abnormal eye movements?

Yes. Concussion commonly affects convergence, focusing and the quick jumps between targets, causing eye strain, reading difficulty and dizziness. These problems usually improve over weeks. A new turned eye or double vision after a head injury needs prompt assessment for nerve or brain injury.

When are abnormal eye movements an emergency?

Go to the ER if new abnormal eye movements or double vision come with slurred speech, facial droop, weakness, severe headache, a drooping eyelid with a large pupil, trouble swallowing or breathing, or drowsiness after a head injury. These can be signs of stroke, aneurysm or a myasthenic crisis.

Is nystagmus always serious?

No. A few beats of nystagmus at the extremes of gaze are normal, and infantile nystagmus is usually stable for life. Nystagmus caused by alcohol or medicines resolves when the substance wears off. New nystagmus with vertigo or other neurological symptoms needs to be checked.