Neuro-Ophthalmology: Definition, Signs and Examination

Our eyes are closely tied to the brain. In fact, about half of the brain is dedicated to processing vision. Unfortunately, this means that diseases of the nervous system are frequently associated with vision and eye problems. If you have a neurologic condition, your doctor may refer you to a neuro-ophthalmologist to evaluate your eyes.

What is neuro-ophthalmology?

An ophthalmologist is a medical doctor who specializes in diagnosing and treating eye diseases. Neuro-ophthalmology is a subspecialty that focuses on eye issues related to neurologic and systemic conditions. Many of these diseases affect your central vision, peripheral vision, and eye muscle movement.

Some conditions that may require management by a neuro-ophthalmologist include:

The optic nerve and retina (located in the back of the eye) are considered extensions of your brain. When the retina picks up visual signals, the optic nerves transmit the information to the brain. The visual cortex is the primary area in the brain that processes visual data. Therefore, anything affecting this visual pathway can cause vision problems.

Causes of vision loss

Any condition that damages the optic nerve can affect your peripheral, color, and in severe cases, your central vision. Vision loss may be permanent if you don’t receive treatment promptly.

Glaucoma. Is one of the most common diseases of the optic nerve. Typically, the eye pressure is elevated and causes progressive damage to the nerve. The result is peripheral vision loss in earlier stages and total blindness in advanced stages.

Optic neuritis. Is inflammation of the optic nerve. The most frequent condition associated with optic neuritis is multiple sclerosis. Optic neuritis causes a sudden decrease in vision, color vision changes, and eye pain.

Intracranial hypertension. Is when the pressure inside the brain increases, causing the optic nerve to swell. Some people have no symptoms, while others may experience intermittent blurred vision, peripheral vision loss, double vision, headaches, and nausea.

Optic neuropathy. Is damage to the optic nerve brought on by infection, inflammation, drugs, nutritional deficiencies, or other systemic and neurologic disorders (such as diabetes, high blood pressure, and autoimmune diseases).

These disorders are some of the more frequent conditions that neuro-ophthalmologists encounter.

Signs of a neuro-ophthalmic condition

If you notice any of the following symptoms, you may need a neuro-ophthalmologic exam:

A sudden onset of these symptoms may be cause for concern. For example, if you develop a droopy eyelid or the droop worsens suddenly, this could indicate myasthenia gravis. Myasthenia gravis is an autoimmune disease that causes muscle weakness throughout your body, including those that control eyelid movement.

If you notice one pupil becomes dilated and unequal in size to the other, this could be a sign of an impending stroke. This finding requires immediate medical attention.

Neuro-ophthalmology exam

A neuro-ophthalmology exam assesses visual acuity, pupil reaction, color vision, eye muscle movement, eye alignment, peripheral vision, and eye health. In addition, a dilated fundus exam allows the doctor to examine your optic nerve and retina.

Other specialized tests

Other specialized tests include:

Computerized visual field

A visual field tests your peripheral vision by showing you blinking lights off to the side while you fixate on a target. Any blind spots can indicate optic nerve damage, a brain tumor, or something obstructing your field of view (like a droopy eyelid).

Optical coherence tomography (OCT)

OCT is a noninvasive test that takes cross-sectional images of your optic nerve and retina. The neuro-ophthalmologist uses OCT to check for optic neuropathies and retinal diseases. For example, an OCT scan can detect optic nerve swelling that occurs in intracranial hypertension.

Fluorescein angiography (FA)

The doctor uses FA to look for abnormal blood vessels or impaired blood flow to your retina and optic nerve, which occurs with some optic neuropathies. Fluorescein is a dye that’s injected into the arm. As the dye flows into the eye, the doctor takes various images highlighting the blood vessels in the back of the eye.

Electroretinogram (ERG) ​​and visual evoked potential (VEP)

An ERG measures the function of the retina, while a VEP measures electrical activity in the visual system. These tests are painless and require placing electrodes on your head. They provide information on how visual signals travel from the eye to the brain. Head injuries, stroke, and other neurologic conditions can affect the visual pathway.

Computed tomography (CT) scan and magnetic resonance imaging (MRI)

The neuro-ophthalmologist may order an MRI or CT imaging of the orbit (eye socket) to see if there is a tumor, swelling, blood, or other problems behind the eye.

In other cases, brain imaging is necessary to look for neurologic issues, especially if the eyes appear normal but have visual symptoms.

Neuro-ophthalmologists often deal with complex diseases that can be vision-threatening but also life-threatening. Consult your eye care professional promptly if you experience any of the symptoms mentioned above. Often, an earlier diagnosis improves the outcome of a disease.