Common causes of eye movement disorders & how they affect vision

Eye movement disorders encompass a range of conditions in which the eyes do not move correctly or symmetrically. These disorders can significantly impact vision, balance, and overall quality of life. Ophthalmologists practicing in Canberra frequently encounter patients concerned about abnormal eye movements and their effects. This blog aims to explain the common causes of eye movement disorders and how they affect vision, helping readers better understand symptoms and seek timely care.

What are eye movement disorders?

Eye movement disorders refer to abnormalities in the way the eyes move, including how they track objects, align with each other, or coordinate with head and body movements. The eyes normally move in a coordinated fashion to ensure clear, stable, and single vision. When this coordination is disrupted, it can cause symptoms like double vision, blurry vision, dizziness, or difficulty focusing.

Common types of eye movement disorders include:

• Nystagmus – involuntary rhythmic shaking or oscillation of the eyes.
• Strabismus – misalignment of the eyes, such as crossed eyes or wandering eyes.
• Oculomotor nerve palsies – paralysis or weakness of the muscles controlling eye movement.
• Internuclear ophthalmoplegia – impaired horizontal eye movement due to brainstem lesions.
• Saccadic and pursuit dysfunctions – problems with quick eye movements or smooth tracking.

Common causes of eye movement disorders

1. Neurological disorders

The brain controls eye movements through complex pathways involving cranial nerves and brainstem nuclei. Neurological problems can disrupt these pathways, causing eye movement abnormalities.

• Stroke or Transient Ischemic Attack (TIA): Can damage brain areas controlling eye muscles, causing sudden eye movement problems.
• Multiple Sclerosis (MS): Demyelination in the brainstem affects eye movement control, leading to internuclear ophthalmoplegia.
• Brain tumors: Masses in the brain can press on nerves or nuclei controlling eye movement.
• Parkinson’s disease: Causes slowed and reduced eye movements.

2. Cranial nerve palsies

The third (oculomotor), fourth (trochlear), and sixth (abducens) cranial nerves control eye muscles.

• Oculomotor nerve palsy: Causes drooping eyelid (ptosis), double vision, and inability to move the eye in certain directions.
• Trochlear nerve palsy: Results in vertical double vision, especially when looking down.
• Abducens nerve palsy: Causes inability to move the eye outward, leading to horizontal double vision. Causes include diabetes, hypertension, trauma, infections, or tumors.

3. Strabismus (Squint)

Misalignment of the eyes occurs when the muscles controlling eye positions are weak or uncoordinated.

• Congenital strabismus: Present from childhood due to developmental issues.
• Acquired strabismus: Due to nerve palsies, trauma, or systemic diseases.

Strabismus often results in double vision or suppression of vision from one eye to avoid confusion.

4. Nystagmus

Involuntary oscillations of the eyes can be congenital or acquired.

• Congenital nystagmus: Usually develops early in life and causes constant eye movement.
• Acquired nystagmus: Caused by neurological disease, inner ear problems, or medication toxicity.

It leads to unstable vision, reduced visual acuity, and sometimes dizziness.

5. Vestibular disorders

The vestibular system in the inner ear helps control balance and eye movements.

• Conditions such as vestibular neuritis, Meniere’s disease, or benign paroxysmal positional vertigo (BPPV) can cause abnormal eye movements like nystagmus and impact vision and balance.

6. Trauma and Injury

Head or orbital trauma can damage muscles, nerves, or brain centers controlling eye movements, leading to disorders like strabismus or nerve palsies.

How eye movement disorders affect vision?

Eye movement disorders can affect vision in various ways:

• Double vision (diplopia): When eyes are misaligned, the brain receives two different images leading to double vision.
• Blurry or unstable vision: Involuntary eye movements cause unstable fixation on objects, making vision blurry or shaky.
• Difficulty focusing: Problems with smooth pursuit or saccades affect the ability to track moving objects or quickly shift gaze.
• Reduced depth perception: Misalignment disrupts binocular vision, impairing depth perception.
• Visual fatigue and headaches: Constant effort to compensate for abnormal eye movement causes eye strain and headaches.
• Dizziness and balance problems: Eye movement disorders linked to vestibular dysfunctions can cause dizziness and imbalance.

Diagnosis

A complete diagnosis typically involves several steps, which may include some or all of the following:

1. Eye examination

A detailed eye exam is the first step. This includes:

• Visual acuity testing.
  
• Assessment of eye alignment and movement range.
• Cover tests to detect strabismus (eye misalignment).
• Tracking and fixation tests to evaluate how the eyes follow and focus on objects.
• Eye movement testing to evaluate saccades, smooth pursuit, gaze holding, and reflexes that coordinate eye and head movement. This helps identify dysfunction in specific cranial nerves or brain regions

2. Neurological evaluation

A neurologist may examine you to identify potential brain or nerve involvement. This includes checking for symptoms such as headache, weakness, or imbalance that might suggest a neurological cause.

3. Imaging (MRI or CT Scan)

Advanced imaging is often used to detect:

• Brain tumors.
• Strokes
• Inflammation
• Nerve compression.
• Demyelinating diseases like multiple sclerosis.

4. Blood tests

These can reveal underlying medical issues such as:

• Diabetes or hypertension
  
• Thyroid dysfunction (e.g., Graves’ disease)
• Infections like Lyme disease or syphilis
• Autoimmune conditions like myasthenia gravis

Treatment

The treatment plan is based on the underlying cause of the eye movement disorder and may involve multiple approaches:

1. Non-Surgical management

• Prism Glasses: Help align visual images and reduce double vision.
• Eye Patching: Used temporarily to relieve symptoms while the condition improves.
• Observation: In cases like diabetic nerve palsy, symptoms may resolve within months without intervention.

2. Medications to manage systemic conditions

Controlling chronic diseases like diabetes, thyroid dysfunction, autoimmune conditions or high blood pressure is crucial to prevent recurrence or worsening of symptoms.

These medications include: 

• Corticosteroids: For inflammatory or autoimmune conditions
• Antibiotics/Antivirals: For infections
• Thyroid medications: If the eye condition is linked to thyroid disease
• Medications for myasthenia gravis: Such as pyridostigmine

3. Surgical treatment

• Strabismus surgery: Corrects misalignment by adjusting the eye muscles
• Orbital decompression: In severe thyroid eye disease
• Neurosurgery: For brain tumors or aneurysms compressing cranial nerves

4. Vision therapy

• Involves eye exercises to improve coordination and reduce strain
• Especially helpful for convergence problems or visual disturbances after stroke

Conclusion

Eye movement disorders can significantly affect vision and quality of life. Early recognition and appropriate treatment are crucial to manage symptoms and prevent complications. If you or someone you know experiences abnormal eye movements or vision problems, consult an ophthalmologist in Canberra promptly to receive expert diagnosis and care.

Author bio 

Dr Parth Shah is an experienced ophthalmologist in Canberra, Australia. With extensive training and experience, he is renowned for his expertise in the field. Dr Shah is dedicated not only to performing successful surgeries but also to patient education. His compassionate approach, combined with technical proficiency, has earned him the trust and gratitude of countless patients. He is a true advocate for eye health and a trusted name in the Canberra ophthalmology community. 

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