Neuro-Ophthalmology

Diplopia – Double Vision

Diplopia, also known as double vision, occurs in one of two ways. Double vision can be present with one eye open (monocular diplopia) or with both eyes open (binocular diplopia). Monocular diplopia is almost always attributable to the focusing elements of the eye. Binocular diplopia occurs when there is misalignment of the eyes. Examples of binocular diplopia include esotropia (crossing of the eyes) or exotropia (one eye “wanders” away to the side). 

A symptom of diplopia is seeing a single object as two images. The two images may appear oriented horizontally, vertically, or diagonally. 

Treatment for diplopia depends on the underlying cause. Options include glasses with prism lenses, vision therapy, Botox therapy, or surgery. 

Anisocoria – Unequal Pupil Size

Unequal pupil sizes, called anisocoria, is a common vision condition. While it is normal for pupils to be slightly different size, large or new anisocoria should be evaluated. Unequal pupil size can be related to a completely benign condition or a life-threatening illness. 

Medications, either eye drops or oral, are a common cause of a harmless change in pupil size. More serious causes of unequal pupil size may be due to aneurysm, bleeding inside the skull, brain tumor, excess pressure on an eye due to glaucoma, meningitis, encephalitis, migraines, or seizures. 

It is important to see a doctor when there is a persistent, sudden, or unexplained change in the size of pupils. It is also important to seek immediate medical attention for a head or eye injury.  You should also seek medical attention if pupil sizes differ and are paired with blurry vision, double vision, sensitivity to light, a fever, headache, loss of vision, nausea, vomiting, a stiff neck, and/or severe eye pain. 

To make a proper diagnosis, a doctor may run blood tests, cerebrospinal fluid tests, CT scans, EEGs, MRI, X-rays of the neck and skull, and tonometry to screen for glaucoma. Recommendations for treatment vary from simple observation to medical or surgical treatment depending on the underlying cause of the condition.

Visual Disturbances

Many neurological disorders present with visual symptoms. However, these symptoms are often difficult to describe. Any visual disturbances associated with other neurologic symptoms such as numbness, weakness, loss of coordination, difficulty speaking or swallowing, trouble walking, or loss of bowel or bladder control should be assessed by a neuro-ophthalmologist. 

Visual disturbances are often associated with neurological disorders such as double vision, nystagmus, reduced visual field and acuity, a full or total loss of vision due to papilledema (or a swollen optic disc). Visual disturbances can be symptoms of other conditions, including, muscular disorders, vascular disease, cancers, or trauma. Patients with diabetes or hyperthyroidism may experience visual disturbances. In some cases, patients with hereditary congenital conditions also may have visual disturbances. 

Migraine syndromes often include a number of visual symptoms. The most common of these are visual auras. Visual Auras are a wide range of visual phenomena including flashes of light, spots, moving colors, or kaleidoscopic patterns. Other symptoms include sensitivity to light, sensation of being overwhelmed by complex patterns, or eye pain. Hormonal changes, medications, chemicals in foods, and even flashing lights can cause migraines. The migraine episode may only last a few minutes, though typically lasts about 20 to 30 minutes. Usually, an ocular migraine does not require treatment and does not cause permanent brain or visual damage. However, it is recommended that you stay still during the migraine episode for safety reasons. If there are lingering visual symptoms, the migraines occur regularly or are increasing in frequency, then see a doctor. Medications may be prescribed to help control the frequency or severity of these migraines. 

Myasthenia gravis is a neuromuscular disorder causing weakness of voluntary muscles, particularly those that control eye movement and eye opening. Ocular symptoms often include double vision and eyelid drooping. Muscle function often improves with rest. While visual symptoms are very common, other muscles throughout the body may be affected causing symptoms of fatigue, weakness, facial paralysis, and even difficulty with breathing or swallowing.

Treatments:

There is no cure for the condition but treatments often include medications and various visual aids.

Eye movement disorders are frequently the result of paralysis of a cranial nerve. Three cranial nerves (on each side) are responsible for controlling eye movements. They include third (oculomotor) nerve palsy, forth (trochlear) nerve palsy, and sixth (abducens) nerve palsy.

Third Cranial Nerve (Oculomotor Nerve) Palsy

Third cranial nerve palsy, also known as oculomotor nerve palsy, can result from head injuries, aneurysms, hemorrhages, tumors, or diabetes.

The symptoms include one eye turning outward while the other is oriented normally, causing double vision. The affected eye is unable to move past the middle when looking inward and is unable to move up and down. There also may be problems with eyelid drooping and dilation of the pupil on the affected side. In some cases the condition causing the palsy may worsen, for example, when a sudden, severe headache occurs due to a ruptured aneurysm.

Treatment will be determined after a neurological exam and testing. Emergency treatment may be required if a life-threatening condition is causing the palsy.

Fourth Cranial Nerve (Trochlear Nerve) Palsy

The cause of a fourth cranial nerve palsy, or a trochlear nerve palsy, is not always easy to identify. The majority of cases are due to head trauma and stroke; however, there are many other causes. Urgent evaluation should be obtained for any patient experiencing new double vision.

The most common symptom is vertical double vision. The two images will appear to be misaligned up and down. Often people will experience some horizontal displacement as well resulting in two images diagonal from one another.

Treatment for this type of palsy may include patching, prisms, or even surgery if necessary.

Sixth Cranial Nerve (Abducens Nerve) Palsy

Sixth cranial nerve palsy also referred to as abducens nerve palsy, can be caused by a head injury, brain tumors, infections, aneurysms, or multiple sclerosis. Depending on the condition, there may be increased pressure on the affected nerve or a decrease in blood flow to the nerve.

Symptoms include horizontal double vision where the two images are side by side. The affected eye is unable to move fully outward and may also move inward when the patient is trying to look straight ahead. Additional symptoms may occur depending on the underlying condition, however, headaches are quite common.

Treatment of sixth nerve palsy depends on the cause. Once the underlying cause is determined the palsy typically resolves itself.
 

Optic neuritis is an inflammatory condition of the optic nerve, which leads to sudden vision loss and often pain with eye movement on the affected side. The vast majority of cases are idiopathic (meaning medical science has yet to find the cause). In a small minority of patients, optic neuritis might be the first symptom of Multiple Sclerosis (MS). The vision loss in optic neuritis returns to normal, or near normal, in most cases without any medical intervention. However, some medications can be used to hasten the recovery of vision.

Optic neuropathy is defined as damage to the optic nerve often due to ischemia, toxins, vascular or blood pressure issues, or pressure within the eye. The most common cause of optic neuropathy is anterior ischemic optic neuropathy. Anterior ischemic optic neuropathy is caused by blood flow interruption to the optic nerve as it enters the back of the eye.

Symptoms include a severe loss of vision either suddenly or over many days, or visual field deficiencies. At the time of vision loss there will be swelling inside the eye, which can be detected by an eye care professional. The condition often occurs in the middle-aged or elderly.

There are numerous causes of optic nerve damage. When visual symptoms are attributed to damage of the optic nerve a search begins to find the cause. Usually, damage to the optic nerve is irreversible. It is important to find out what damaged the optic nerve so that the other eye doesn’t become involved as well.
 

Pseudotumor cerebri is a process affecting the brain that appears to be, but is not, a tumor. It is often reversible. It is more common in premenopausal, obese women. It is important to monitor vision, as there is potential for visual loss. Follow-up MRI or CT scans may be done to rule out hidden cancer.

Signs and Symptoms:

• Increased pressure within the skull (increased intracranial pressure)
• Headache
• Buzzing sound in ear
• Dizziness
• Nausea
• Double vision
• Partial or permanent loss of vision
• Blurred vision
• Symptoms may get worse during physical activity, especially when tightening the stomach muscles

Treatment:

• Mild: Fluid or salt restrictions. Medications such as corticosteroids, glycerol, acetazolamide, and furosemide.
• Moderate or severe: Surgery to relieve pressure on the optic nerve. These may include lumbar puncture to optic nerve sheath decompression, or shunt procedures.
• Weight loss may be one of the most important long-term factors leading to improvement.

Brain tumors can cause vision loss through inflammation or pressure on areas of the brain that control vision. Not all brain tumors are malignant (cancerous), in fact, most are not. Unfortunately, that doesn’t mean that they can’t cause problems by just being there and placing pressure on the brain.

There are several symptoms associated with brain tumors depending on the areas of the brain affected by the tumor. Visual symptoms can often be the first sign of a brain tumor. Sudden vision problems, including blurry vision, double vision, or a loss of side or peripheral vision often occur. New or suddenly different headaches may often occur. Treatment of brain tumors depends on the type of tumor and the age of the patient. Options may include surgery, drug therapies, radiation therapy, chemotherapy, or any combination of these treatments. A multidisciplinary approach is critical to the successful management of brain tumors. A team of neuro-oncologists, neurosurgeons, radiation oncologists, and neuro-ophthalmologists need to work together on these complicated cases.