Neuro-Ophthalmology

Neuro-ophthalmology is an ophthalmic subspecialty that addresses the relationship between the eye and the brain, specifically disorders of the optic nerve, orbit, and brain, associated with visual symptoms. Today, neuro-ophthalmologists provide comprehensive clinical care to a broad spectrum of patients with visual disturbance from optic nerve diseases, central nervous system disorders, ocular motility dysfunction, and pupillary abnormalities.

Types of Problems Dealt With:

Patients seen by the Neuro-ophthalmology Service generally fall into the following groups:

1. Patients with visual loss related to the nervous system 
We investigate and treat patients who have acute or chronic visual loss from disorders of:

• a) The OPTIC NERVE, such as optic neuritis, ischemic optic neuropathy, toxic and nutritional optic neuropathies, hereditary optic neuropathies, idiopathic intracranial hypertension (pseudotumour cerebri), optic nerve sheath meninigiomas, optic nerve gliomas and thyroid eye disease.
• b) The VISUAL PATHWAYS arising for example, from stroke or stroke-like disease, tumour compression (e.g. pituitary tumours)

2. Patients with eye movement disorders
Eye movement disorders causing diplopia or an abnormal head posture may be caused by:

• single or multiple cranial nerve palsies
• muscle disorders (myopathies)
• neuromuscular junction disorders such as myasthenia gravis.
• Eye movement disorders may also cause oscillopsia (jerky /wobbly vision).
  Such disorders fall under the broad heading of nystagmus.

3. Patients with unexplained visual loss
Many patients have visual loss that cannot be readily explained by a routine ophthalmic examination. To help discover the cause of such visual loss, neuro-ophthalmologists utilize a wide variety of diagnostic including visual evoked potentials, electroretinograms and neuro-imaging.

4. Pupil Disorders
Abnormalities of the pupil managed by the neuro-ophthalmologist include Horner’s syndrome and Adie’s syndrome. We employ a variety of pharmacological tests and perform pupillometry to diagnose these conditions.

5. Eyelid and facial disorders relating to the nervous system
We manage patients with blepharospasm and hemifacial spasm as well as patients with ocular myasthenia gravis.

A typical Neuro-ophthalmology consultation:

Consists of in-depth history-taking and clinical examination. Necessary investigations may include visual field testing, blood tests, neuroimaging with either computed axial tomography (CT) or magnetic resonance imaging (MRI), neurophysiologic and electrophysiologic tests.
Treatment is tailored according to the underlying disorder. When indicated, patients are referred to, and co-managed with specialists from other disciplines, such as neurologists, neurosurgeons and interventional neuroradiologists.
We encourage patients attending a neuro-ophthalmology consultation to bring with them any relevant investigation results (MRIs, CT scans, blood test results, electrophysiology reports, etc) that they may already have.

What are the common symptoms of neuro-ophthalmic diseases?

Symptoms that are more common in neuro-ophthalmic disease include:
• visual loss
• visual disturbance
• diplopia
• unequal pupils
• eyelid and facial spasms

Optic Nerve Diseases

The optic nerve is the only nerve in the body that can be directly examined by a doctor. It connects the eye to the brain. It is like an electrical cable that brings visual information from the eye to the brain for processing.

The optic nerve can be affected by:
1. Inflammation
2. Ischaemia (inadequate blood supply)
3. Compression 
4. Raised intracranial pressure
5. Trauma

Inflammation normally presents a rapid loss of vision. Colour vision is frequently affected. Occasionally inflammation of the optic nerve may cause pain behind the eyes, especially during eye movements. A diagnosis can usually be made on clinical grounds alone. However, because inflammation is often related to diseases that can affect other parts of the body, such as connective tissue disease and multiple sclerosis, some blood investigations and an MRI may be necessary. Treatment with steroids may be required.
Like inflammation, Ischaemia also usually presents rapid loss of vision, although it is usually painless. It is most commonly related to other vascular diseases such as hypertension and diabetes and is often spoken of as “a stroke of the optic nerve”.
Treatment is usually directed at controlling risk factors such as hypertension, diabetes, hyperlipidaemia and smoking.
Optic nerve dysfunction resulting from a compressive lesion (usually a kind of tumour), usually presents a slow, progressive, painless loss of vision. The cause is usually apparent on CT Scan or MRI. Referral to a neurosurgeon may be necessary.
Raised intracranial pressure can cause a headache with early morning nausea or vomiting, transient loss of vision, or focal neurological disturbances in other parts of the body (such as weakness or loss of balance). CT Scan or MRI imaging is usually necessary as is a lumbar puncture to obtain cerebrospinal fluid for analysis. Referral to a neurologist or neurosurgeon is usually required.

Eye Movement Disorders

Many diseases affect movement of the eyes. This includes:
1. Local (orbital) disease causing restriction of movement. 
2. Disease affecting the nerves to the muscles causing weakness. 
3. Diseases affecting the transmission of signals between nerve and muscle 
4. Diseases of the muscle 
5. Diseases affecting portions of the brain that control movement

Eye movement disorders can present in one or more of the following ways:
1. Double vision 
2. Blur vision
3. Unstable (“shaky”) vision

The vision in each eye (when tested separately) is often normal. However, visual disturbance occurs when both eyes are used. Eye movement disorders may also be accompanied by dizziness, unsteady gait, headache and weakness involving other parts of the body.
Eye movement disorders that occur suddenly require urgent medical attention to rule out serious conditions such as the rupture of blood vessels leading to the brain.
Investigation and treatment is directed at the cause of the eye movement disorder.