Neuro-Ophthalmology

Neuro-Ophthalmology encompasses visual problems that are related to the nervous system; that is, visual problems that do not come from the eyes themselves.

We use almost half of the brain for vision-related activities, including sight and moving the eyes. Neuro-Ohthalmology, a subspecialty of both Neurology and Ophthalmology, requires specialised training and expertise in problems of the eye, brain, nerves and muscles. Neuro-Ophthalmologists complete at least 8 years of clinical training after medical school and are usually board certified in Neurology, Ophthalmology, or both.

Although some problems seen by Neuro-Ophthalmologists are not a particular worry, other conditions can get worse and cause permanent visual loss, or become life threatening. Sometimes the problem is confined to the optic nerve or the nervous system and other times it is related to a general medical condition. Neuro-Opthalmologists have unique abilities to evaluate patients from the neurologic, ophthalmologic, and medical standpoints to diagnose and treat a wide variety of problems. Costly medical testing is often avoided by seeing a neuro-ophthalmologist.

Some of the common problems evaluated by Neuro-Ophthalmologists include: Optic nerve problems (such as optic neuritis and ischemic optic neuropathy), Visual field loss, Unexplained visual loss, Transient visual loss, Visual disturbances, Double vision, Abnormal eye movements, Myasthenia gravis, Unequal pupil size, and Eyelid abnormalities.

Read more about:

• Anterior Ischaemic Optic Neuropathy
• Optic Neuritis
• Optic Atrophy
• Microvascular Cranial Nerve Palsy
• Migraine
• Nystagmus
• Double Vision
• Intracranial Hypertension (Pseudotumour Cerebri)
• Visual Field Loss

Anterior Ischaemic Optic Neuropathy

Ischaemic Optic Neuropathy occurs when there is poor blood flow to the optic nerve. It is the most common cause of sudden decreased vision in the over fifties.

What is Anterior Ischaemic Optic Neuropathy?

Ischaemic Optic Neuropathy (ION) is a sudden loss of central and/or side vision because of poor blood flow to the optic nerve (the information 'wire' from the eye to the brain). It is the most common cause of sudden decreased vision in patients older than 50 years. It is usually not related to other illness although may be more common in people with diabetes or high blood pressure.

What causes Anterior Ischaemic Optic Neuropathy?

It is not clear what causes the loss of blood supply to the optic nerve. These episodes may occur when there is a sudden drop in blood pressure (following an operation or with blood loss after an accident). Patients who smoke, or who have diabetes or high blood pressure, may be at a higher risk for ION.

What are the symptoms of Anterior Ischaemic Optic Neuropathy?

Sudden loss of central or side vision (especially the lower half) is the most common symptom of ION. Vision loss is usually at its worst when first noticed, and in most eyes permanently remains at this level.

How is Anterior Ischaemic Optic Neuropathy diagnosed?

A medical eye exam is performed, including measuring your visual acuity, testing how your pupil reacts to light and examining the back of your eye. A visual field test may also be performed.

How is Anterior Ischaemic Optic Neuropathy treated?

At this time there is no effective treatment for ION. In people with central visual loss, up to 40% of patients may improve their central vision over time, though visual field problems are unlikely to recover. It has been suggested that Aspirin and vitamin supplements may decrease the chance of an episode in the opposite eye.

Frequently asked questions about Anterior Ischaemic Optic Neuropathy

What did I do to make this happen?

In most cases, there is nothing you or anyone else did to create this problem. The anatomy of your optic nerve is what you were born with. It is possible that smoking and high blood pressure may have increased your risk. Ultimately, we still do not understand the trigger that will produce the ischaemic event.

Will my vision get worse?

Within the first few days or weeks, worsening is possible though this is uncommon. To reduce this risk stop smoking and make sure that your blood pressure is adequately but not overly aggressively controlled.

Will my vision get better?

In patients with central loss, there is a 40% chance of improvement although the visual field tends to remain the same.

How can I prevent involvement of the other eye?

Taking 75mg of Aspirin a day and vitamin supplements may reduce the chances. Avoiding cigarette smoke and proper treatment of elevated blood pressure may also help.

Optic Neuritis

What is Optic Neuritis?

Optic neuritis is the most common cause of sudden visual loss among young people.

It is often associated with discomfort in or around the eye, particularly with eye movement. The optic nerve is like a cable of electric wires, and consists of more than one million separate tiny wires or nerve fibres. Each nerve fibre carries a part of the visual information picture (or image) we see to the brain. If some or all of the nerve fibres become inflamed and do not function properly, vision becomes blurred.

What causes Optic Neuritis?

It is not entirely clear though it is generally suspected that autoimmune disease and/or previous viral infection may play a role. In the most common form, the optic nerve is attacked by the body's overactive immune system. In children especially, optic neuritis develops following a viral illness such as mumps, measles or colds.

What are the symptoms of Optic Neuritis?

Optic neuritis usually develops over a few hours to days. One may notice the following symptoms:

• Blurred vision in one eye or both, especially after exercising or a hot bath. The blurring may be like a blob of grease in one area or it may affect the whole picture in one eye.
• Vision is dim, as if the lights are turned down.
• Colours appear dull or faded.
• Pain behind the eye, particularly when moving the eyes.

How is it Optic Neuritis diagnosed?

The Ophthalmologist will measure your vision, examine how your pupil reacts to light and inspect the inside of your eye.

How is Optic Neuritis treated?

Fortunately over 90% of people recover their vision without any treatment, generally over a period of weeks to months. Some may have residual 'washed out' vision and have disturbances when exercising or taking a hot bath. This is related to the damaged myelin (insulation) that surrounds the nerves. It often settles with time and patients who notice this problem are no more likely to get worse.

Most people who have one will never have another episode, but recurrences (second attacks) can occur, either in the same eye or in the other eye.  They are treated in the same way as the first attack.

Frequently asked questions about Optic Neuritis

What caused this to happen?

We do not have a complete understanding of optic neuritis. It is likely that it represents a combination of a particular form of immune system reaction with a previous stimulation possibly by a virus.

What is going to happen to my vision?

In the vast majority of patients, your vision will improve. It may not improve to normal, but it is likely that there will be a sustained improvement whether or not you are treated.

Can treatment with steroids make this better?

Treatment with intravenous (drip) steroids has been demonstrated to accelerate recovery but it will not on average change the ultimate level of recovery. We have no way to guarantee that vision will recover and in some patients it will not.

Optic Atrophy

The Optic nerve is the cable that takes the message from the eye to the brain to enable you to see.

It is only 1.5mm in diameter and has approximately 1 million nerve fibres packed into this small space. When some of these nerves are damaged it causes loss of visual signal to the brain, which is experienced as loss of vision. This is called Optic Atrophy.

Some of the symptoms and signs of Optic Atrophy include: Blurred vision, reduced colour appreciation, disturbance to the field of vision, dimming of what one can see along with poor pupil reaction to light and optic nerve paleness (the healthy optic nerve is pink).

Treatment very much depends on the cause. Blood tests, x-ray, magnetic resonance imaging (MRI) and some other tests can help find out. If it is felt to be due to active inflammation then Steroids may help reduce the amount of damage.

Getting the diagnosis correct is important and will therefore direct possible treatment. Should the damage to the nerve be permanent then looking at magnification aids in the Visual Aid Clinic and being registered as having sight difficulty can be of enormous help.

Microvascular Cranial Nerve Palsy

Microvascular cranial nerve palsy (MCNP) is one of the most common causes of acute double vision in the older population.

It occurs more often in patients with diabetes and high blood pressure. This condition almost always resolves on its own without leaving any double vision.

What is Microvascular cranial nerve palsy (MCNP)?

Any nerve cannot function properly when its blood flow is blocked. If the 6th (Abducens) cranial nerve is affected, your eye will not be able to move to the outerside and you will be aware of double vision seeing side-by-side images. The double vision will be worse when looking in the direction of the affected muscle. If the 4th (Trochlear) cranial nerve is affected you will be aware of vertical double vision. You may be able to eliminate or decrease the double vision by tilting your head towards the opposite shoulder. The 3rd (Oculomotor) cranial nerve supplies 4 of the 6 muscles. It also controls the height of the eyelid and pupil size. When this nerve is affected, your eye may be limited in its up and down movement and gaze towards the nose. The eyelid may droop.

What causes MCNP?

It is not always clear what causes the blockage to the tiny blood vessels to the cranial nerves. In some cases diabetes or high blood pressure may be risk factors. The nerves are not permanently injured, and over a period of 6-12 weeks, normal function should recover. If the double vision does not go away it is very important to tell your ophthalmologist.

What are the signs and symptoms of MCNP?

The signs of MCNP are usually problems with movement of your eyes, which lead to blurred, or double vision. If severely affected, your eye may not be able to move at all in one or more directions. Sometimes there may only be a slowing of movement.
Symptoms and findings may include:

• Weakness in one or more eye muscles.
• Blurred vision that improves by closing the other eye.
• Double vision.
• Pain in or around the eye (related to lack of blood flow to the covering of the brain) which commonly occurs at the onset of double vision.
• Drooping eyelid (called ptosis)
• Enlarged pupil.

If you have multiple MCNPs, involvement of the pupil or have a younger age of onset, a neurological exam and imaging study may be necessary. Anyone diagnosed with MCNP should have their blood pressure and blood sugar checked to make sure they do not have diabetes or hypertension.

How is MCNP treated?

There is no known method of accelerating the natural recovery time for MCNP. Patching the other eye may treat double vision. If the double vision persists, it may be possible to use prism glasses or to consider eye muscle surgery if recovery has not been complete.

Migraine

Migraine is a common neurological condition occurring in at least 15-20% of the population and in up to 50% of women.

Classical migraine usually starts with visual symptoms (often zig-zag lines, coloured lights or flashes of light expanding to one side of your vision over 10-30 minutes), followed by a single-sided pounding headache. The headache is usually associated with nausea, vomiting, and light sensitivity. Sometimes visual symptoms and even neurological dysfunction may occur without the headache. This is called 'migraine-variant'. Common migraine may cause only a headache felt on both sides of the head. This form of migraine may be responsible for the headaches that many people may have attributed to tension, stress or sinus pain.

What causes Migraine?

While it is not clear exactly how a migraine works, it is believed that the basic cause of migraine is an abnormality in the neurotransmitter serotonin, an important chemical used by your brain cells. During a migraine attack, changes in serotonin affect blood vessels in your brain, often causing the vessels to constrict. These changes in blood flow decrease the oxygen supply to the brain. If this oxygen supply is decreased long enough, a stroke is possible. Fortunately this is rare.

Certain foods may trigger a migraine attack including aged cheese, nitrates (often found in cured meats and processed foods), chocolate, red wine and monosodium glutamate (a flavour enhancer frequently found in some foods). Caffeine, aspartame (artificial sweetener) and alcohol may also trigger migraines. Hormonal changes are frequently associated with migraine, especially pregnancy, use of birth control pills, and menstrual periods or menopause.

Patients often attribute migraine to stress. While stress probably does cause migraine, it may affect the frequency of attacks. Interestingly, however, most migraine attacks seem to occur following stress relief, often at the beginning of a weekend or holiday. People who experience migraine often have a family history of migraine or motion sickness.

What are the symptoms of Migraine?

The most common sign of migraine is a headache lasting for hours or days. Symptoms generally include:

• Pounding pain on one side of your head (or steady pain on both sides of the head).
• Sensitivity to light and sound.
• Nausea, vomiting.
• Visual symptoms (usually in both eyes but often to one side) with some of the following characteristics:
• A spot of blurring that expands to one side over 10-30 minutes.
• An expanding border often described as zig-zag lines, 'shimmering' or resembling 'heat waves' or 'sparklers'.
• Vision loss in one eye only, involving the entire field or only the upper or lower section.

Rare symptoms include double vision, change in lid position or change in pupil size. In very rare cases, the visual problems with migraine may not entirely resolve. This may be due to a stroke associated with migraine.

How is Migraine treated?

Treatment usually first involves avoiding factors known to precipitate a migraine attack, such as foods, environmental triggers such as perfume and medication such as birth control pills. Aspirin and Ibuprofen etc may reduce the severity of an attack and are more effective if taken with some caffeine. There are some very effective prescription medications that deal with the chemical imbalances of migraine (including Imigran, Naramig).

If the migraine attacks are severe or frequent enough, medication may be required on a regular basis (prophylactic). The most commonly used prophylactic medication groups are tricyclics, beta-blockers, calcium channel blockers and some anti-seizure medications.

Frequently Asked Questions about Migraines

How could I be having a migraine when I do not have a headache?

While headache is the most common symptom, visual symptoms and even neurological dysfunction may occur without a headache. The important features are the frequent repetitive nature of the events and most importantly the transient nature with no evidence of residual dysfunction. While migraine can lead to a stroke this is rare and all of these patients deserve a work up to make sure nothing else is going on.

Do I have to take medications?

No. The medications are designed to either relieve symptoms during an attack or decrease the frequency of attacks. If the symptoms are not bad, the episodes occur infrequently, or they respond to 'over-the-counter' pain medications it is not necessary to take anything.

Nystagmus

Nystagmus is a problem with the movement of the eyes and is characterised by an involuntary oscillatory movement.

About 1 in every 1,000 people have nystagmus. There are many different types. This is a condition that should be accurately diagnosed by an Ophthalmologist or Neurologist as new onset nystagmus can be the first sign of a serious disorder. A Neuro-Ophthalmologist is a specialist who combines these two specialty interests. Children with Nystagmus will have their eye care looked after by a Paediatric Ophthalmologist.

Because poor vision is associated with Nystagmus you may be able to get additional help by being registered as having sight difficulty. Low vision aids such as a magnifier and other such devices are available from the Visual Aid Clinic. This is particularly important with regard to children at school who therefore may need extra time studying.

The treatment of Nystagmus depends a lot on what the 'cause' is.

Double Vision

Diplopia is another word meaning double vision.

It may seem obvious but double vision is seeing two of the same object and not blurred vision. Causes for this include poor fitting spectacles, unevenness of the surface of the eye (Cornea), cataract formation and disturbance of the retina (light sensitive part of the back of the eye). Double vision otherwise comes from the two eyes not being in the correct alignment.

As general rule, if it is coming from the two eyes in an on / off nature then the likely diagnosis if that of a squint which has been 'hidden' for many years now showing itself. It may be more obvious when tired or unwell. This may be able to be corrected with new spectacles, eye exercises and prisms attached to the spectacles.

If the double vision is there all the time clues to the cause can be found in a detailed history of possible trauma, other illness such as thyroid problems, speed on onset and whether the second image is above / below or side-by-side. As Double Vision can be part of a more generalised problem it is important that it is correctly identified.

The treatment of diplopia very much depends on the cause. Blood tests, x-ray, magnetic resonance imaging (MRI) and some other tests can help find out.

Intracranial Hypertension (Pseudotumour Cerebri)

What is Pseudotumour cerebri (PCT)?

Pseudotumour cerebri (PCT) is a condition in which high cerebrospinal fluid (CSF) pressure inside your head can cause problems with vision and headache.

In PCT, the flow of the CSF (a clear fluid that bathes the brain and the spinal cord) is blocked from flowing back out of the head as it should, leading to high pressure inside your head. This pressure results in swelling of the optic disc at the back of the eye, which can damage (sometimes permanently) the optic nerve, causing vision loss. High pressure may also give damage to the nerves that move the eyes, resulting in double vision.

What causes Pseudotumour cerebri (PCT)?

The reason for the decreased outflow of CSF is not clear. Because this condition seems to occur more often in overweight young women, a hormonal influence is suspected. Pseudotumour may also occur in children, men, and patients who are not overweight.

What are the symptoms of Pseudotumour cerebri ?

The most common symptoms of high CSF pressure inside the head are headache and visual loss. Symptoms of Pseudotumour cerebri include:

• Dimming, blurring or graying of vision.
• Difficulty seeing to the side.
• Brief visual disturbance (often associated with bending or stooping)
• Double vision.
• Rushing noise in the ears.
• Nausea and vomiting.

How is Pseudotumour cerebri diagnosed?

Your ophthalmologist will carefully measure your vision, check the light reaction of your pupils, examine the back of your eye and may evaluate your field of vision. Because other conditions may produce similar symptoms to PCT, an MRI scan is necessary for accurate diagnosis. A spinal tap is also necessary to check for elevated CSF and to make sure there are no other CSF abnormalities.

How is Pseudotumour cerebri treated?

If you have no significant headaches or evidence of vision loss (including visual fields) no treatment may be necessary. If you do experience these problems, certain medications used in treating glaucoma (Diamox - Acetazolamide) can lower the CSF pressure in the head by reducing the production of this fluid.

Frequently Asked Questions about Intra Cranial Hypertension

Do I have a tumour?

While the most commonly used term "Pseudotumour" has that word in it, by definition patients with PCT specifically do not have a tumour. A tumour may cause increased intracranial pressure and therefore be mistaken for PCT but this should be seen on an MRI scan.

When will this go away?

It was thought in the past that PCT was a self-limited disease that resolved over 1-2 years. While it is possible for the pressure to vary over time, prolonged problems with CSF outflow may result in long-term increased pressure.

Do I need to be treated?

If you have no significant headaches or evidence of visual loss (including visual fields) no treatment may be necessary (weight reduction is always a good idea). The decision to start treatment or to alter treatment from dietary to medical to surgical intervention depends on the function of the optic nerve and the status of the headaches.

I hate those visual fields. Can't you just look at the back of the eye?

Unfortunately the appearance of the optic nerve (papilloedema) does not tell us how well your optic nerve is working.

Do I need another spinal tap?

In the past we treated PCT with repeated spinal taps. This is not effective in most patients. While we would like to know the intracranial pressure, re-measuring becomes important only when there is evidence of further damage to the optic nerve (worsening visual field or visual acuity) or worsening headaches.

Visual Field Loss

Visual Field is the wider extent of your vision, the objects that you can see at the periphery of your sight when looking straight ahead.

What is visual field loss?

When you look straight at something you expect to be able to 'see things out of the corner of our eye'. This is because we have a wide extent of vision. This is called our Visual Field.

Normally one eye can see about 180 horizontally and about 140 vertically. With 2 eyes working together the area is a little larger.

Unfortunately some things can reduce this peripheral vision resulting in visual field loss

How is visual field loss treated?

Visual field loss can be caused by problems with the eye itself, with parts of the brain we use for seeing, or with the nerves connecting the eye to the brain.

It is possible to measure how good your peripheral vision is with a Visual field test.

At Yorkshire Eye Hospital we have the most advanced equipment available to measure visual fields with the 'top of the range' Humphrey' Visual Field Analyser'. This advanced computerised machine projects spots of light. If you see the spot you press a button. The machine then works out where you can see & looks to see if there are any weak areas. For most tests, each eye is tested separately.

Testing usually takes about 15 minutes. Our experienced staff explain the test and guide you through it. It is completely painless, and it won't affect your vision afterwards.

You don't need to do anything special to prepare for a test, but if you are tired or "under the weather" you may find it harder to do. If you have an appointment planned and this is the case it may be worth phoning up to see if it would be better to re schedule it.

Visual field tests may be done for several reasons.

• to monitor an eye problem (e.g. Glaucoma)
• to help us diagnose a medical condition (e.g. some strokes)
• to see if someone's vision is good enough for certain tasks (e.g. driving)

We are able to carry out a wide variety of tests, and in particular the DVLA Esterman test to see if your vision is up to the standard required for driving.

Examples of how problems in different places produce different patterns of visual field loss can be seen.